A review of recent advances in catalytic hydrocracking of heavy residues

Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

Contents lists available at ScienceDirect

Journal of Industrial and Engineering Chemistry journal homepage: www.elsevier.com/locate/jiec

Review

A review of recent advances in catalytic hydrocracking of heavy residues Ramakanta Sahu a,b, Byung Jin Song a,c, Ji Sun Im a,d, Young-Pyo Jeon a,d, Chul Wee Lee a,d,* a

Division of Green Chemistry & Engineering Research, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600, Republic of Korea School of Applied Sciences (Chemistry), KIIT University, Patia, Bhubaneswar, Odisha 751024, India c Department of Chemistry, Sungkyunkwan University, Suwon 440-746, Republic of Korea d School of Science, University of Science and Technology (UST), Daejeon 305-333, Republic of Korea b

A R T I C L E I N F O

Article history: Received 3 September 2013 Received in revised form 16 January 2015 Accepted 16 January 2015 Available online 23 January 2015 Keywords: Hydrocracking Vacuum residue Heavy oil Catalyst Process

A B S T R A C T

Non-conventional feeds such as vacuum residue (VR) and heavy oils have shown an alternate source for the production of high value transportation fuels, as it is abundantly available. These feeds are of low quality due to presence of impurities like CCR, asphaltenes, sulfur, nitrogen and heavy metals. Several process technologies have been developed to upgrade these feeds through fixed-bed, moving-bed, ebullated-bed, slurry-phase reactor or a combination. Hydrocracking in slurry-phase type reactor is a prominent technology to convert low value feeds into high value transportation fuels and petrochemical products. Varieties of homogeneous and heterogeneous catalysts comparison are reviewed for hydrocracking of VR and heavy oils. Recent studies on hydrocracking reaction mechanisms are represented in this report. Choice of process technology is implemented by considering the feed properties, product demand and economic benefit as well as environmental concerns. This review addresses the most recent hydrocracking technologies, catalyst development and important issues related to conversion of non-conventional feeds. ß 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

Contents Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Sources of petroleum vacuum residue and heavy oil. . . . . . . . . . . . . . . . . . . . . . . Characteristics of vacuum residue and heavy oil . . . . . . . . . . . . . . . . . . . . Vacuum residue upgrading process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Qualitative description of different upgrading processes . . . . . . . . . . . . . . Hydrocracking technology. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Development of hydrocracking process in slurry-phase reactor . Slurry-phase hydrocracking process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Catalysts for slurry-phase process . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Solid powder catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Oil-soluble dispersed catalysts . . . . . . . . . . . . . . . . . . . . . . . . . . . Water-soluble dispersed catalysts . . . . . . . . . . . . . . . . . . . . . . . . Hydrocracking reaction mechanisms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Current and future developments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

. . . . . . . . . . . . . . . . .

13 13 14 15 15 16 17 18 19 19 19 20 21 22 22 23 23

* Corresponding author at: Division of Green Chemistry & Engineering Research, Korea Research Institute of Chemical Technology (KRICT), Daejeon 305-600, Republic of Korea. Tel.: +82 42 860 7381; fax: +82 42 860 7388. E-mail address: [email protected] (C.W. Lee). http://dx.doi.org/10.1016/j.jiec.2015.01.011 1226-086X/ß 2015 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

13

Introduction World-wide fuels and petrochemicals are synthesized from coal, petroleum oil and natural gases. According to the United States Energy Information Administration (EIA), total oil demand in the world is expected to grow up to 123 mmbpd (million barrels per day) by 2025. In addition, the organization of petroleum exporting countries (OPEC) has estimated that production will be approximately 61 mmbpd by 2025, which is less than half of the demand. At the same time, non-OPEC countries are also expecting a steady increase in petroleum oil production (62 mmbpd) by 2025 [1]. It indicates that the petroleum refine industries will continue to grow as before. Due to rapid population growth, the consumption of fuels, energy and petrochemical products has increased tremendously. Driving forces for the petroleum refinery industries to upgrade heavy oils and residues are (1) to get high quality transportation fuels (2) middle distillate products [2–5], (3) depletion of crude oil sources, (4) shrinking of conventional crude oils supply and (5) increase of cost price [6]. Heavy oils or vacuum residue (VR) is considered as an alternate suitable source for transportation fuels, energy and petrochemicals to fulfill the requirements of modern civilization. Therefore, petroleum refineries will be partially replaced by heavy or extra heavy oil refineries in the near future [7,8]. Huge quantity of oil sand, and bitumen, are also widely distributed and deposited across the globe. Due to their similar properties with VR and heavy oils, these feedstocks are also appropriate source for the synthesis of transportation fuels and petrochemicals. In recent decades, researchers have emphasized the development of refining techniques based on cheaply available feedstocks, such as coal, low grade petroleum oil or wax [9], heavy oil [10], waste material [11], VR and natural gases. These feedstocks are used for the synthesis of many petroleum products including transport fuels and other low boiling point liquid products, plastics, synthetic fibers, solvents, fertilizers, pesticides, detergents, lubricants, fine chemicals, pharmaceuticals, waxes, and coke [12,13]. The goals for upgradation of heavy oils and VR are to decrease viscosity and boiling point, demetallation, desulfurization, level of other impurities and increase H/C ratio with high commercial values. A number of catalysts synthesis process [14] and technologies have been developed to upgrade heavy oils, waste materials and VR [11,15]. Among all technologies for the conversion of heavy oils and VR, slurry-phase hydrocracking is the most considerable as it is applicable to upgrade high impurities feeds. Hydrocracking of heavy oils with metal dispersed catalysts is the most suitable to obtained low boiling point or middle distillate with high value products [9,10]. In order to understand the catalytic behavior in slurry-phase reactor, several model substrates are utilized and detail reaction parameters are optimized [16–18]. Catalysts used for this process have dual functionality in character (cracking and hydrogenation). Hydrogenation occurs in compounds of olefins, aromatics, sulfur, nitrogen and oxygen while cracking occurs at C–C bonds. Cracking reactions are endothermic while hydrogenations reactions are exothermic. Hence, net heat is evolved in the reactor. Thus, the reactor design and thermally stable catalysts are very much important for hydrocracking of VR and heavy oil. Perhaps, slurry-phase reactors and transition metal dispersed catalysts are the most suitable option for hydrocracking of heavy oils and VR. The slurry-phase hydrocracking systems have high conversion and minimization the yield of low value by products (gas, coke and other high boiling point liquid) formation.

Fig. 1. Relationship between crude oil price and API gravity.

approximately 6 trillion (6  1012) barrels (bbl) of heavy oils are available worldwide: 2.5  1012 bbl are in Western Canada, 1.5  1012 bbl are in Venezuela, 1  1012 bbl are in Russia, 0.1– 0.18  1012 bbl are in the United States (USA) and rest of the mass is located in other countries. The largest heavy oil reservoirs in the world are located at the north of the Orinoco River in Venezuela. Heavy oils are also located in various countries and are being produced in India, Colombia, Indonesia, China, Mexico, Brazil, Trinidad, Argentina, Eastern Europe, Ecuador, Egypt, Saudi Arabia, Oman, Kuwait, Turkey, Australia, Nigeria, Angola, the North Sea, Rumania, Iran, and Italy [19,20]. The Alberta oil sand (including the Peace River), Wabasca, Athabasca and Cold Lake are also well known for heavy oil reservoirs [2]. One third of the useful heavy petroleum resources are found in the Western Canadian oil sands [21]. Most of these resources are currently untapped due to high viscosity [20]. The price of heavy oil varies according to API (American petroleum institute) gravity, as shown in Fig. 1. This figure compares values that were reported in 2002 with those from 2006 [22]. About 4,100 million metric tons per annum (MMTPA) worldwide petroleum refining capacity has reached. In petroleum refining industries, two types of residues are generated. Atmospheric residues (AR, TBP >343 8C) are generated at the bottom of an atmospheric distillation unit. AR is again treated in vacuum distillation tower. Heaviest fractions obtained at the bottom part of the vacuum distillation column tower at 0.003–0.01 MPa are called vacuum residues (VR). These residues have atmospheric boiling points above 550 8C (Fig. 2).

Sources of petroleum vacuum residue and heavy oil Heavy oils, extra-heavy oils and bitumens are found all over the world. The International Energy Agency (IEA) estimated that

Fig. 2. TBP curve for feeds with different API gravity values.

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

14 Table 1 World processing capacity, in MMTPA [23]. Process Thermal De-asphaltene Hydroprocessing Residue FCC Total

U.S.A.

Japan

Europe

Rest world

Total

99.5 13.0 30.5 31.5

4.0 1.0 30.25 12.5

140.0 0.5 9.0 10.5

143.5 5.0 49.8 37.0

387.0 19.5 119.5 91.5

174.5

47.8

160.0

235.2

617.5

According to the report from 1998, approximately 617.5 million metric tons (MMT) of petroleum residues were upgraded or converted in various processes worldwide, as shown in Table 1 [24]. Currently, approximately 725 MMT petroleum residues are processed through various conversion processes. Conversion of residues or heavy oil has always been aimed to refiners to obtain value-added products [24]. Characteristics of vacuum residue and heavy oil Heavy oils are similar to petroleum oils, but it is difficult to recover from the sub-surface of the Earth via conventional means. The term ‘‘heavy oil’’ has been chosen arbitrarily because these oils require thermal stimulation to recover from the reservoir. Heavy oil, or VR, is complex, black in color, highly dense, and extremely viscous in nature with API gravity between 10 and 208. It is also high molecular weight, low hydrogen to carbon (H/C) ratio, highly viscous (at room temperature) materials. These materials contain impurities such as nickel, vanadium, iron, calcium, silica, compounds of nitrogen, oxygen, and sulfur. Based on polarity difference, these materials can be classified into 4 organic fractions like saturates, aromatics, resins, and asphaltenes [25–30]. Percentages of impurities (heavy metals, nitrogen, sulfur, etc.) and physical properties of heavy crude oils (source of VR) are shown in Table 2. The properties of VR are varied according to origin (place) and synthetic route. VR can be converted into lighter oil or more value-added products using bottom of the barrel conversion processes or residue upgrading processes. Elemental analysis, feed compositions of various fractions and ICP analysis are provided in Table 3. Saturated compounds generally have a carbon number in the range of C38–50 and relatively low heteroatom content. According to structural studies, these compounds consist of long alkyl chains with few or negligible naphthenic and aromatic rings. These compounds are volatile; little coke is formed during the hydroconversion process. Compared to saturated compounds contained in heavy oil or vacuum residue, aromatic compounds have higher molecular

Table 3 Analysis of crude oil residue: composition, SARA, elemental and ICP analyses [34,35]. Composition (wt % of total) Component

Whole crude HC

Maya crude oil Saturates 20.7 Aromatics 26.5 Resins 29.9 Asphaltenes 20.6 Kern river crude oil 21.8 Saturates Aromatics 28.7 Resins 37.6 Asphaltenes 5.5 Arabian heavy crude oil Saturates 20.1 Aromatics 31.0 31.2 Resins Asphaltenes 12.2

AR, 345 8C+

S

N2

V

Ni

Ni

V

0.9 24.6 39.0 36.3

3.3 8.2 39.6 48.9

0.4 17.9 81.7

3.3 17.7 79.0

2.7 13.0 84.3

2.7 13.1 85.6

<1 30.7 60.3 8.8

2.7 4.2 77.2 15.8

7.5 52.8 39.8

4.5 63.0 32.5

1.8 22.8 75.4

2.7 16.7 80.6

<1 29.6 46.3 23.9

6.7 8.4 43.8 41.1

3.4 25.2 71.4

10.4 28.2 61.8

5.2 14.2 80.6

1.6 11.8 86.6

weight hydrocarbons, with carbon numbers in the range of C41–53. These compounds have simple structures compared to resins and asphaltenes [31]. The aromatic compounds have low heteroatom content. Resins are tacky, viscous and easy vaporized carbon compounds present in VR or heavy oils. Structurally, resins consist of (40– 53 wt%) aromatics and naphthenic carbons. Aromatic rings are composed of long non-bridged alkyl chain carbon [32]. Components, frequency of the aromatic rings, and naphthenic compounds depend on the source and origin of the crude oil extraction process [33]. Asphaltene fractions are in various color (from brown to black), non-volatile, amorphous substances which exist as colloids in the VR or heavy oils. The asphaltenes are composed of nitrogen, oxygen, sulfur, vanadium and nickel compounds. These compounds contain a stack or cluster of naphthenic and aromatic molecules, fused ring aromatic molecules, small aliphatic side chains and polar functional groups (Fig. 3). Asphaltenes are insoluble in n-alkanes such as n-pentane and n-heptane, but soluble in benzene or toluene [36]. VR and heavy oils are poor in quality due to presence of asphaltenes, heavy metals and hydrocarbon, and heteroatoms

Table 2 Composition and physical properties of different residues [30]. Crude oil

Alaska, north slope Canada, Athabasca California, Hondo Kuwait, Export North Sea, Ekofisk Venezuela, Bachaquero Mexico, Maya Iranian Canada, Cold Lake Arabian, Safaniya

Gravity (8API)

Ni + V (ppmw)

S (wt%)

C-residue (wt%)

Residue yield (vol.% of crude) AR 343 8C+

VR 565 8C+

14.9 5.8 7.5 15.0 20.9 9.4

71 374 489 75 6 509

1.8 5.4 5.8 4.1 0.4 3.0

9.2 15.3 12.0 11.0 4.3 14.1

51.5 85.3 67.2 45.9 25.2 70.2

21.4 51.4 44.3 21.8 13.2 38.0

7.9 – 6.8 13.0

620 197 333 125

4.7 2.6 5.0 4.3

15.3 9.9 15.1 12.8

56.4 46.7 83.7 53.8

31.2 – 44.8 23.2

Fig. 3. Major structural components of the vacuum residue [37].

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

15

[34]. Asphaltenes and resins are significant fractions in above feeds. Therefore, these feeds must be upgraded before used as fuels or chemicals. Vacuum residue upgrading process In petroleum refining industries, 60 wt% (vol.) of VR are generated at the bottom of the vacuum tower during the crude oil conversion. Disposal or use of VR is not satisfactory. Therefore, conversion of VR into more valuable products such as fuels and chemicals is extremely important. At the same time, there are no clean and economical VR conversion processes which can meet the market standards. Developments of upgradation of VR or heavy oils are related to the development of process technology, replacement of hydrogen source (instead of pure hydrogen) and more active and selective catalysts toward value added products are needed. Catalytic performance enhancement can be achieved by employing steps below: 1. Use of different transition metal precursors, additives and preparation methods. 2. Use of other metals rather than conventional metal such as Mo, Ni, Co and W. 3. Modifying of supports properties (texture, acidity and chemical composition). 4. Using new active phases, such as carbides and nitrides, rather than the traditional sulfide. 5. Using promoters such as phosphorus (P), fluorine (F) and boron (B) on the catalysts. For economic point of view, process conditions may be milder, and hydrogen sources may be used. Various process technologies for VR up gradation are described below. Qualitative description of different upgrading processes Heavy oil or VR upgrading technologies can be broadly classified into following categories: (a) carbon rejection (thermal) processes: visbreaking, steam cracking, residue fluid catalytic cracking, and coking; (b) separation processes: solvent deasphalting; and (c) hydrogen addition processes: hydrocracking [38]. In aforementioned processes catalysts may or may not use. Since 1913 carbon rejection process is used in the petroleum refining industries. In this process, the feeds (larger molecule) are heated under inert atmospheric pressure to fracture them into smaller molecules. Internal hydrogen attached to carbon molecule is redistributed among the various components such that some fractions increase their H/C atomic ratios while others decreased their H/C atomic ratios. In this processes induced carbon coke is formed. Conversely, during hydrogen addition processes, the H/C ratio of the feedstock is increased using an external hydrogen source in presence of suitable catalysts. Solvent de-asphalting and thermal (gasification, delayed coking, fluid coking, flexicoking and visbreaking) processes are non-catalytic while residue fluid catalytic cracking (RFCC) and hydroprocessing (fixed-bed hydrotreating and hydrocracking, slurry-phase hydrocracking, ebullated-bed hydrotreating and hydrocracking) are catalytic. Fig. 4 illustrates the worldwide distribution of residue conversion technologies. Solvent de-asphalting involves physical separation (metals and asphaltenes) of constituents in the feed according to their molecular weight instead of their boiling point [39–41]. The feeds are mixed with light paraffinic solvents such as propane, butane, npentane and n-heptane. Asphaltene and other impurities are insoluble in the paraffinic oil. The insoluble portion is separated from the mixture. High energy costs, low demand for motor fuel

Fig. 4. Historical worldwide residue conversion selection [24].

and the limited uses of de-asphalted products are the limitations of this process. However, interest in de-asphalting is increasing. Solvent de-asphalting processes may be sufficient for residue upgrading [42]. Thermal processes (carbon rejection) are an important for the conversion of VR or heavy oils [43]. Generally, thermal cracking is carried out at moderate pressure; the hydrogen is transferred from larger to lighter molecules, resulting carbon or coke. In this processes, the H/C ratio is decreased. In gasification, feeds are heated at high temperatures (>1,000 8C) in absence of air. Therefore, heated feeds are converted into major products such as gas, carbon black and ash [44,45]. Gasification and its combination technologies are alternative efficient processes for power generation and other sectors [46,47]. Poor selectivity and difficulty in product separation make the gasification processes is less popular than other processes. Delayed coking has been chosen by many refiners for VR up gradation because the chemical composition of feeds can be varied. During this process, the partial conversion of a liquid product results in completely metal and carbon free products [48– 50]. The product selectivity depends on the experimental conditions (temperature, pressure and reaction time). Large amounts of coke formation and low yields of liquid product make this process more expensive. Even considering these disadvantages, delayed coking is still frequently used for refiners. Fluid coking and flexicoking are other thermal processes. In these processes coke carries heat from the burner to the reactor while serving as a reaction site for the conversion of VR into various products. The residence time of the liquid reactant in the reactor determines the coke and product formation [51]. The operating conditions and costs of thermal processes are shown in Table 4 and in Fig. 5, respectively. Visbreaking is the oldest, cost effective option for residual up gradation. Generally, 7 wt% gas and gasoline like product is observed [52]. However, during this process, asphaltene content does not vary in the product. Therefore, stable fuel oil is obtained. This process is suitable in those areas which demanded relatively low motor fuel. If the motor fuel demand increases in these areas and there are no other refiners, delayed coking is used [42]. A major portion (approximately 63 wt%) of petroleum residues are up graded by thermal processes such as visbreaking and delayed coking. Depending on up grading condition and feedstock composition, various products like naphthas, middle distillates, vacuum gas oils and coke are formed. Recently, significant number of thermal cracking projects is involved to convert VR. Thermal processes and technologies based on coking have disadvantages of producing a large amount of low value by-products that required further processing. The integrated processes are expensive and time consuming. Therefore, the thermal processes are less important than catalytic upgrading processes of VR.

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

16

Table 4 Thermal processing technologies and reaction conditions. Residue technology

Licenser

Operation conditions Temperature (8C)

Gasification Delayed coking

Fluid coking Flexicoking Visbreaking

Chevron Texaco BB Lummus FOSTER Wheeler/UOP Conoco-Phillips ExxonMobil Conoco-Phillips Halliburton KBR ABB Lummus

Table 5 Comparison of different hydroprocessing reactors.

>1,000 480–515

480–565 830–1,000 450–510

Pressure (MPa) 0.61

0.07

Maximum (Ni + V) in feed, ppm Tolerance for impurities Max. conversion to 550 8C, wt% Unit operability

Fixed bed

Moving bed

Ebullated bed

Slurry bed

50–250

50–400

100–600

>300

Low 50

Low 50

Average 80

High 95

Good

Difficulty

Difficulty

Difficulty

0.34–2.0 Table 6 Comparison of different process for residue upgrading [60].

Operating cost, $/bbl

9

Simplicity Flexibility Cost Product quality Residue conversion level Rejection as fuel oil Rejection as coke No. of units worldwide Recent trends Environmental pollution On stream factor Problems

8

7

6

Processes Fig. 5. Operating costs for various processes.

Residue fluidized catalytic cracking (RFCC) is an extension of fluidized catalytic cracking (FCC) which was developed in early 1980. This method requires a vapor phase for the catalytic cracking reaction that exhibits better selectivity for gasoline and low gas yields than thermal processes. Residues (VR and AR) have high boiling point as well as high content of impurities (metals and heteroatom) which makes the feeds difficult to vaporize. At the end of the reaction, metal and coke deposits on the catalyst surface, as a result catalyst gets deactivate. To process these feedstocks, it must contain relatively low amounts of metal, sulfur, and asphaltenes, or required good quality feedstocks. Therefore, the usefulness of RFCC is limited in industrial applications [23]. Hydrocracking technology During the past three decades, hydrocracking has gained prominence in light petroleum refinery processes [53,54]. After full industrialization of light petroleum oil, hydrocracking processes are gradually applied for heavy oil and VR upgradation [55,56]. Various hydrocracking reactor technologies such as fixedbed, ebullated-bed, moving-bed or slurry-phase reactors are used to upgrade heavy residues [57]. The principles of these reactor operations are almost same but differing with respect to some technical minutiae and tolerance of impurities [58]. Table 5 shows the different types of reactors used for hydrocracking of VR [59] and comparison is represented in Table 6 [60]. In Table 7, different processes and their licensers are offered. Product selectivity depends on catalyst properties (shape, size, active sites, chemical composition etc.) and experimental conditions. The reaction conditions for each technology are entirely different. Therefore, nature of the feed, use of proper reactor system

Non-catalytic

Catalytic

Extraction

H2 addition

High Low Low Low Medium

Medium High Medium Medium Medium

Medium Low Medium Medium Medium

Low High High High High

Medium High Large

Medium Medium Large

Medium Medium Average

Medium Medium Average

High High

Medium Medium

Medium Nil

Medium Low

Poor Medium Medium High Coke disposal Heavy residue High energy H2 require

Table 7 Residue hydroconversion processes. Reactor type

Process

Licenser

Fixed bed

Continuous catalyst replacement (OCR) UFR, Up-flow reactor Hycon, Bunker type reactor Hyvahl, swing reactor concept

Chevron Lumus Global (CLG) Shell (Bunker flow) Axen (Swing reactor) Shell IFP (Axen)

Ebullated bed

H-Oil T-Star LC-Fining

Axen (HRI/IFP) Chevron ABB Lummus

Slurry system

MICROCAT-RC Veba combi-cracking Hydrocracking distillation hydrotreating (HDH) Cash, Chevron activated slurry hydroprocessing EST, Eni slurry technology CanMet

Exxon Mobil Veba Oel Intevep Chevron Eni Technologies Snamprogetti Energy Research Laboratories,Canada

and catalysts are very much important for the hydrocracking of VR. Generally, hydrotreatment of the middle distillates or a high API gravity feeds are conducted in fixed-bed reactors, while more complex feeds are used in moving-bed or ebullated-bed reactors. A fixed-bed reactor requires continuous withdrawal of deactivated catalysts and immediate addition of fresh catalysts. In moving-bed reactors, the fresh catalyst enters at the top of the reactor, and the deactivated catalyst leaves the bottom of the reactor [60–63]. In a moving-bed reactor, the catalyst expands, and thus, the pressure drop can be reduced in some extent [64]. Generally, the hydrocracking of heavy feeds in fixed-bed reactor requires mixed or multiple beds of catalysts. Detailed catalysts syntheses and their applications in fixed-bed reactor systems have previously been

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

reviewed [65,66]. If the feed quality is too low for a fixed-bed reactor, moving-bed reactors in series or combinations of ebullated-bed with fixed-bed reactors can be effective [67]. In general, supported metal catalysts are more preferable in fixed-bed or ebullated-bed reactors system to hydrocrack heavy feeds. The catalytic activities usually depend on the active metals and supports (acidic or basic), like alumina, mixed alumina oxide (Al2O3–ZrO2, Al2O3–MgO, etc.), microporous (zeolites) and mesoporous materials. Generally, supported catalysts are prepared by wet or incipient wetness impregnation methods; the active components are deposited on the supports. The impregnated catalysts are usually calcined, reduced and used for the hydrocracking reaction. Before the reaction, pretreatment with a sulfur agent is performed either in situ or ex situ to convert the catalyst into its sulfide form. Diffusion of feeds, pressure drop and mass transfer are the problems in fixed-bed, ebullated-bed or moving-bed reactors. The intraparticle mass transfer between liquid and solid phases, particle size, and amplitude of agitation speed are also problems which must be taken into account. Diffusion can be controlled using a high agitation speed (>300 rpm) and an ideal mixture of reactants [68–70]. Thus, hydrocracking processes in these reactors have limited commercial applications. To resolve these important issues and make the process industrially applicable, slurry-phase hydrocracking is an alternate option. Development of hydrocracking process in slurry-phase reactor Hydrocracking has a unique benefit. The limitations associated with the above processes (especially hydrocracking reactions in fixed-bed reactors) can be overcome in slurry-phase reactors. Therefore, VR conversion in slurry-phase reactors will most likely meet the necessary requirements. In 1920–1930, the first slurryphase hydrocracking process was developed to produce low quality distillates from liquefied coal. In the first attempt, this process was carried out under high pressure, resulting in high costs and other operational issues. Afterward, slurry-phase hydrocracking was recognized as a potential solution for converting difficult VR into transportation fuels. Coal and VR were used for hydrogenation in World War II and 1964, respectively. In the late 1970s, there was little development of heavy oil or VR hydrocracking in slurry-phase reactors; after 1980, interest increased due to increase in the middle distillate price and demand. Slurry-phase hydrocracking processes are currently being researched worldwide. In this process, thermal cracking and hydrogenation occur in a reactor with varying feed to hydrogen ratios. Under high hydrogen pressure, the coke deposits on the catalysts which may convert into gaseous organic compounds. The gaseous products leave the catalyst surface which makes catalyst in active form by lengthening of its life time [71]. However, during slurry-phase hydrocracking processes, the catalyst can only be used once because the deactivation caused by nitrogenous and sulfurous compounds, as well as high molecular weight organometallic complexes (asphaltenes) which must be accounted. Hydrocracking is the most versatile of the modern heavy feed conversion processes. The flexibility of the operating conditions with respect to both the feedstock and product separation has provided the most economical refinery balance relative to supply and demand. This flexibility in operation may be attributed to the development of specific families of catalysts, specifically the design of processing schemes that allow the catalysts function efficiently. Commercial feedstocks range from naphtha to residua, allowing for numerous choices of hydrocracker products. It is possible to produce high octane gasoline at one time and middle distillates such as jet fuel, diesel oil, or fuel oil at another time. The proportion of motor and jet fuel production can be varied as needed.

17

During hydrocracking, three phases are observed in the reactor: solid (coke, metal impurities, unreacted organic carbon compounds and catalyst), liquid (light naptha: IBP-130 8C, heavy naphtha: 130– 220 8C, atmospheric gas oil: 220–340 8C, light gas oil: 340–450 8C, heavy vacuum gas oil: 450–540 8C and super heavy vacuum gas oil: 540–847 8C, non-distillate: >847 8C) and gas (unreacted H2, CH4, CO, CO2, C2H6, H2S, C3H8, C4H10, etc.) phases [72]. According to the boiling point distribution, liquid hydrocracking products can be measured quantitatively using simulated distillation (SIMDIST). Generally, ASTM (American Society for Testing and Materials) D2887 and D5307 cover the boiling range of 55–538 8C (n-parafine: C5–C44) [73,74]. A high temperature simulated distillation (HTSD) method that covers the boiling range of 36–750 8C (n-alkane: C5–C120) is also used for quantitative measurement of distillate products [75]. ASTM D2892 and D5236 are better for correlating the true atmospheric boiling points of liquid hydrocracking products [76,77]. Other methods can also be used to determine the concentration of the hydrocracking liquid products [78,79]. Depending upon physical status of feedstocks, two types of hydrocracking processes are being practiced in industry. If feedstocks are heavy distillates obtained from direct straight run cracking of petroleum oil, the process is called distillate hydrocracking, and if the feedstock is a residue obtained from straight run refining, the process is called residual hydrocracking. Properties of the different feeds are given in Table 2. Generally, residue hydrocracking is carried out at relatively higher temperature compared to distillate hydrocracking. Therefore, residue hydrocracking requires different types of catalyst. Catalysts employed in residue hydrocracking tolerate the metal impurities and the asphaltenes present in the feedstocks. In distillate hydrocracking, the supports are mainly alumina or other micropore material, while hydrocracking of residue requires mainly acidic or mesoporous supports because the residues have a high molecular weight and size. Residual hydrocracking catalyst should possess twice of surface area and pore volume of the catalyst. The thermal cracking mode may prevail in the distillate process, while catalysts are needed during the residue process. Selection of a catalyst and a reaction system are extremely important. The process should be chosen by the types of feed and contacting pattern of the reactants. Currently, developing a process for heavy oil or VR refining without the aid of a highly efficient catalyst is difficult to imagine. Hydrocracking is no exception. In fact, its progress has depended on the development of catalysts with requisite activities and selectivity. The hydrocracking catalysts are bifunctional in nature. Two functions are (1) the cracking of high molecular weight hydrocarbons (resins) to form smaller hydrocarbons C–C bond breaking, and (2) hydrogenation of the unsaturates (straight chain alkenes or aromatics) present in the feeds or generated during cracking. Except this, catalysts also playing a role to terminate the radicals formed during C–C cracking. Generally, supported sulfide catalysts containing group VIB and VIII metal especially cobalt, molybdenum, tungsten or nickel are used in this process. However, impurities present in the residues decrease the catalytic activities [80]. Hydrocracking requires a limited range of reaction conditions, a large reactor, and high hydrogen partial pressure. In addition, hydrocracking also requires low impurities and moderated API gravity feeds. These factors can be reduced by using a suitable catalyst with improved stability as well as by selecting a proper reactor which must work under moderate operating conditions. The catalyst properties for hydrocracking of heavy feedstocks are very much important because the feedstock contains metal and other impurities that decrease the oil quality. Therefore, the chemical composition and textural properties such as size, shape,

18

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

Fig. 6. Effect of pore diameter and specific surface area on the hydrocracking reaction.

surface area, and porosity have a great influence. Macroporous and mesoporous catalysts may be a good choice for surface hydrocracking reactions. Pore diameter is an important factor when converting various feedstocks (Fig. 6). Feedstocks with a high content of metals and asphaltenes require large pore catalysts that allow these large size reactant molecules to enter the catalytic active sites; a small pore catalyst promotes the external deposition of metal and carbon, leading to pore plugging [80–83]. Hence, design and synthesis of a porous catalyst having high activity for VR hydrocracking is a challenge to researcher. Some slurry-phase hydrocracking processes have been studied on an experimental scale, while others have been tested in pilot scale or some have industrialized. Some technologies have been tested with a solid catalyst; some have used expensive catalysts, have incurred high processing costs. Slurry-phase hydrocracking process The VEBA-combi-cracking (VCC) process was developed for coal liquefaction in Germany. Red mud (iron containing material) and a fine coke powder of Bovey coal are used as catalysts. In this process, 90–94 wt% conversion and 4000 barrel/day product could be achieved. However, high pressure (15–27 MPa) and large amount of catalyst (5 wt%) are obstruct to use of this method [84–88]. The M-coke technology was developed by the Exxon Mobil group. They used phosphor-molybdic acid and molybdenum naphthenate as catalysts under 17 MPa at 440 8C. In this reaction, 90% conversion was obtained. Although, catalysts show high activities and rate but this process is limited to the experimental scale (1 drum/day) due to the high cost of the catalyst [89–91]. The MICROCAT-RC process was also developed by Exxon Mobil for converting petroleum residues. They prepared finely dispersed (particle size less than 1 mm), oil-soluble manganese and molybdenum catalysts for a hydrocracking reaction. In this process, coke formation was suppressed [92–94]. Catalysts recovery is an issue. Early in the 1990s, development of the Eni Slurry Technology (EST) process began to process heavy oils, VR and bitumen with a high content of metal and carbon residue. In this process, H2S gas is pretreated with highly disperse oil soluble molybdenum catalysts. The pretreated catalyst is hydrocracked under 16 MPa hydrogen pressure, at 400–425 8C reaction temperature [95]. Asphaltenes and metals present in the feeds are less soluble in oil. Hence, metal particles along with asphaltenes appear as precipitate on the catalyst in form of coke. To overcome this problem, the asphaltenes

and metals are separated out before it used for hydrocracking. The catalyst screening was studied in laboratory micro-reactor and a bench scale autoclave [96–98]. In 1999, this process was tested in a pilot plant with various de-asphaltenes and demetals heavy oils at a capacity of 0.3 bbl/day. In 2005, Eni/Snamprogetti designed a reactor for converting Athabasc bitumen, Venezuela Zuata and other heavy crude oils. The properties of different residues are explained in Table 8. Initially, the capacity of this reactor was 1200 bbl per stream day (BPSD); by 2012, its capacity reached 23,000 BPSD [99]. In Italy, the EST process is moving toward the commercial stage. Since the hydrotreating processes began in 2005, more than 230,000 bbl of black feed has been successfully processed in a commercial demonstration plant (CDP) unit. Venezuelan company INTEVEP developed HDH technology. With this technology, an inexpensive natural ore located in Venezuela is used as the only catalyst. Although, the catalyst is inexpensive, this process remains complex. The presence of large amount of solid material on the catalyst, difficulty in separation of unconverted oil, and catalyst locations (found in Venezuela only) are the limitations of this processes [100,101]. HCAT upgrading technology was invented by the Headwaters Technology Innovations Group. Low quality feeds such as heavy oil and residues are converted into high quality synthetic fuels. Molecular catalysts are synthesized in situ to obtain a high oil conversion. During this process, sedimentation is reduced in the reactor. The advantages of this process are, prolonged the catalytic activity, feed flexibility, uniformity of product quality, high conversion (95 wt%), and the two phases (gas and liquid) of reaction product. Utah (Oil Corporation’s Porvoo Refinery at South Jordan) was the first refinery to implement Headwater’s HCAT heavy oil upgrading technology for commercially application. The HCAT process upgrades Neste oil in an ebullated-bed reactor, converting 500,000 bbl of heavy oil in every day; at least 200,000 BPD will be added by 2014 [101–105]. CANMET is a highly efficient hydrocracking conversion process. In this process, an additive is used to prevent the deposition of coke on the catalyst which enhanced the conversion of high boiling feeds to low boiling products. At the initial stage, tar sands and later stage, bitumen and heavy oils are upgraded [106,107]. Large amount (1–5 wt%) of FeSO4 is used during a Canadian CANMET process. This process is not viable due to the difficulty encountered when separating the products from the

Table 8 Performance of different feedstocks in the EST process [87]. Feedstock properties

Ural

Arabian heavy

Zuata

Maya

Athabasca

Specific gravity (g/cm3) API gravity 500 8C+ content (wt%) H/C S (wt%) N (wt%) Ni and V (ppm) n-C7 asphaltenes (wt%) CCR (wt%) Product yield Gas (HC + H2S) Naphtha (C5-170 8C) AGO (170–350 8C) VGO (350–500 8C) DAO (500 8C+) Upgrading performance % HDS % HDM % HDN % CCR reduction % Conversion

1.0043 9.4 91 1.494 2.60 0.69 74/242 10.5 18.9

1.0312 5.7 96 1.366 5.28 0.45 52/170 19.5 22.9

1.0559 2.5 95 1.349 4.24 0.97 154/697 19.7 22.1

1.0643 1.5 99 1.333 5.24 0.81 132/866 30.3 29.3

1.0147 8.0 60 1.420 4.58 0.48 70/186 12.4 12.4

11.5 5.8 32.5 29.8 20.4

10.9 4.9 30.6 29.2 24.4

15.0 5.9 35.6 29.8 13.7

9.9 3.9 26.9 34.9 24.4

12.9 4.1 39.1 32.1 11.8

86 >99 54 97 >99

82 >99 41 97 >99

82 >99 51 98 >99

84 >99 52 96 >99

83 >99 47 95 >99

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

unconverted bottom oil and the catalyst. Though, product formation rate is high, but the desulfurization and denitrogenation rate is not satisfactory [108,109]. In early 2000s, UOP explored several options for evaluating commercially feasible hydrocracking processes using industrially left over VR. They concluded that CANMET hydrocracking is more efficient than the other technologies invented for VR conversion. In 2006, UOP began to review the engineering design and operation conditions of CANMET hydrocracking process. In 2007, they tested the use of a V2O5 catalyst, before acquiring the rights to perform the CANMET hydrocracking process. At present, this process is called the UOP uniflex process [107,110]. Japanese scientists invented the super oil cracking (SOC) technology. This technology requires a horizontal furnace for the reaction, a highly dispersed superfine powder and a highly active transition metal catalyst with good anticoking effects. This process requires a high reaction pressure (20–22 MPa), temperature (480 8C), short resident time and expensive catalysts. In this reaction, 3,500 bbl/day VR has been processed [88,111–113]. Limonite ore is used as a catalyst in the KOBE STEEL LTD process. To increase its activity, the catalyst is pulverized to particles smaller than 2 mm. The iron present in this catalyst might be an economical choice for cracking of heavy oil or VR [114]. Other technologies, such as Aurabon and IFP, have also been developed [115] using oil-soluble molybdenum and cobalt naphthenate catalysts. These catalysts are highly active for hydrogenation. However, they are inactive for thermal cracking of C–C bond. This bond is cracked by free radicals generated by the metal. The above technology has been thoroughly reviewed by several authors [113,116]. Catalysts for slurry-phase process Slurry-phase hydrocracking processes exhibit high activity and selectivity toward the product. The catalytic activity may decreases due to the formation of coke, deposition of undesirable products, metal and asphaltenes on the catalyst surface. Thermally or attrition of catalyst are also responsible for deactivation. Depending upon the physical properties of catalyst there are two categories of catalysts, i.e., heterogeneous and homogeneous (water soluble and oil soluble) are used for slurry-phase hydrocracking processes for VR. Solid powder catalysts Different Co/Mo ratio supported on carbon nanotube catalysts were prepared by impregnation method. Gudao VR was treated with prepared supported catalyst in a 500 mL of reactor at 430 8C with 8 MPa H2 pressure. The catalytic activity was greatly influenced by the Co/Mo ratio. A ratio of 0.5 provided the best catalytic activity. At this reaction condition, 5 wt% gas, 43.17 wt% atmospheric gas oil, 51.1 wt% vacuum gas oil and 4.4 wt% coke was observed [117]. Ni–Mo sulfide (NMC) supported on activated carbon was prepared and used for hydrocracking of Middle Eastern petroleum residue. The experiments were conducted at 350– 450 8C for 2 h with initial 5 MPa H2 pressure. Various products were identified and the yield was calculated [118]. Hydrocracking of Arabian VR was carried out in a batch type autoclave using commercially available Ni–Mo supported on alumina with a two-stage rise in reaction temperature. A high conversion (above 50 wt%) was obtained without sludge formation. Two stage reaction temperatures are more advantageous as the first stage (390 8C) is very effective for suppressing sludge formation, while the second stage (430–450 8C) produces the distilled products [119]. To convert Marlim VR, a disposable Australian iron-slurry (AL) and NiO–MoO3–Al2O3 (NiMo) catalysts were used at 440–460 8C under 14.7 MPa H2 pressure. Depending on the reaction conditions

19

and catalyst used for hydrocracking, 54–83 wt% conversion was achieved [120]. In another experiment, VR was treated with a red mud catalyst in a temperature range of 470–500 8C at 15 MPa H2 pressure for 2 h. A significant improvement in the desired product yield, including naphtha, diesel and vacuum gas oil, was observed [121]. An iron particulate component and metal phthalocyanines, such as iron oxides, iron sulfides or mixture of both, are used in the Breaden process. When the reaction was carried out in the presence of 7 wt% Fe2O3 and 400 ppm of cobalt for hydrocracking of VR, the coke yield was only 0.4 wt% [122]. Khulbs reported a greatly reduced coke deposition on the reaction zone when a finely divided fly ash catalyst was used [108]. In addition, 10 wt% metal salts such as iron, cobalt, molybdenum were coated with various types of coal, such as lignite, bituminous and sub-bituminous coal. The coated materials were crushed, sieved to less than 60 mesh size particles and treated with VR [123]. Supported Ni and Mo along with additives such as Si, Al and Ti oxide catalyst having particle size of 4–20 mm was prepared by Lott. These additives promote the production of middle distillate oil [124]. Iron petroleum coke catalyst was prepared by grinding of petroleum coke particles (8–16 mesh) and the particles of an iron compound in heavy oil to form additive slurry. 5 wt% coke catalysts are used to convert heavy oil into hydrocracking products [125]. VR from distilled vacuum units (DVU-VR) was hydrocracked in a supercritical aromatic hydrocarbon solvent using acid-treated activated carbon. Supercritical reaction was conducted at 400 8C with 3.45 MPa H2 pressure. High conversion (69.2 wt%) with low coke formation (13.5 wt%) and high quality oil products such as 13.0 wt% of naphtha, 34.9 wt% middle distillate, 27.1 wt% vacuum gas oil, and 11.2 wt% residue were obtained [126]. Recently, AR of Mongolian crude oil sample was hydrocracked using commercially available NiMo/Al2O3 catalyst at 450–470 8C for 2 h under 10 MPa of H2 pressure. At 470 8C, the AR conversion and yield of the light fraction reached 90.6 wt% and 53.9 wt%, respectively. Similar results were obtained for DQAR MEAR residues [127]. Iranian VR is upgraded in two-stage processes. In the first stage, the pyrolytic upgrading of the virgin feedstock is performed, while in the second stage, the cracked oil produced from the first stage is hydrocracked using nanoporous catalysts (Na-ZSM-5, Na-Y, H-SAPO-34 and AlMCM-41) [128]. Ni–Mo based mesoporous alumina and mesoporous silica-alumina (MSA) with different textural properties were prepared and evaluated for hydrocracking of VR derived from Maya crude oil. More than 70 wt% conversion of VR and asphaltenes into lighter hydrocarbons was achieved. The reutilization and deactivation by coke deposition has also been studied; coke deposition occurs mainly in first run [129]. Hydrocracking of extra heavy residues with NiMo/nano structured g-Al2O3 (NiO/MoO3 mass ratio 0.33) catalyst was conducted in an autoclave at 260–300 8C with 5 MPa H2 pressure. 55.2 wt% conversion could be obtained; exceeding the results obtained using NiMo/H-ZSM-5 catalyst [130]. Few aspects were achieved during VR or poor quality heavy feeds hydrocracking; reductions of coke formation, prevention of pore blockage of the supported catalyst. High reaction rate is achieved by using of oil soluble based catalysts [131–134]. Oil soluble catalysts are synthesized using sulfides, or oxides, or combinations of both or a salt of a group IV through group VIII metal (Mo, Ni, Co, W, Cr, V, Fe, Cu, Zn, etc.) along with organic acid. Oil-soluble dispersed catalysts For preparation of oil soluble catalysts, metals are introduced into the oil soluble precursors to form an organometallic compound. Catalyst is homogeneously dispersed in the reactor

20

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

Table 9 Oil soluble dispersed catalysts for slurry bed process. Licenser

Catalyst components

Feed

Amount of catalyst

Result

Ref.

Exxon Research and Engineering Co.

Molybdenum alicyclic or naphthenate Fe2O3 and Mo naphthenate

Heavy oil with CCR > 5 wt%

50 wt% reduction of CCR

[135]

50 wt% reduction of CCR Coke yield 1 wt%

[136]

Iron molybdenum

Cold Lake crude oil

Conversion >50 wt%

[137]

CrO3 tert-butyl alcohol

Heavy oil with CCR 5–50 wt%

50–200 ppm Solid, noncolloidal catalyst 50–200 ppm in situ Prepared in situ Can be recycled 0.5–2.0 wt% Solid particles with low SA and PV 0.1–2.0 wt% Solid chromium-containing catalyst

Conversion of 80–85 wt%

[138]

Iron pentacarbonyl or molybdenum 2-ethyl hexanoate Mo, Ni acetylacetonates or 2-ethyl hexanoate

Athabasca bitumen + 50 wt% diluent

90 wt% Conversion 0.3 wt% coke yield

[139]

Athabasca bitumen

0.1–0.5 wt% Well-dispersed colloidal particles 50–300 ppm mixture of asphaltene and metal doped coke Can be recycled

Low coke yield

[140]

Chevron Inc.

Mo or W salts of fatty acids (C7–C12)

Arabian crude

300–1000 ppm

80 wt%

[141]

Universal Oil Products Co.

Non-stochiometric vanadium sulfide

Wyoming sour crude oil

Well-dispersed colloidal particles

High Ni, V removal activity

[142]

Alberta Oil Sands Technology and Research Authorit

Cold Lake crude oil

containing residue or heavy oil. Sufficient hydrogen pressure is supplied to enhance the reaction rate. Table 9 shows some typical oil soluble catalytic reaction results. Ammonium salt of a vanadium sulfide catalyst is used by UOP [142]. This compound forms a colloid with the asphaltene or organometallic compounds present in the feeds. This catalyst reduces the coke formation, metal and asphaltene in the reaction products. Alberta Research Co modified an oil soluble catalyst that forms a colloid in the reactor. Strausz used molybdenum naphthenate and nickel di-2-ethylhexanoate to hydrocrack heavy oils and VR. The catalyst reacts with feeds to form dispersed micelles. This micelle forms by ligand exchange and molecular complexation processes [140,143]. The additives like iron pentacarbonyl or molybdenum 2-ethyl hexanoate are mixed with heavy oil and VR and hydrocracking reaction is carried out [139]. These catalysts are well dispersed, forming colloids with sulfur moieties in the feeds which delay the coke growth at higher temperature. Consequently, a high conversion can be obtained in this process. Single molybdenum dithiocarboxylate, nickel and iron naphthenate, as well as their mixtures used for hydrocracking of Liaohe VR. When bimetallic multicomponent oil soluble catalysts were used, a complex sulfide formed, inducing a slight synergism for hydrocracking of VR [144]. Fushun Research Institute of Petroleum and Petrochemicals (FRIPP) synthesized oil soluble catalysts for hydrocracking of residue in suspension bed reactor. Detailed catalytic evaluation study was carried out by Dong. Gudao VR was hydrocracked using an oil soluble catalyst. A 70 wt% yield of distillate (>538 8C) was obtained. The catalyst showed high activity and inhibited coke formation [145]. Oil soluble Co–Mo bimetallic catalysts were prepared using layered ammonium cobalt molybdate. The carboxylate of oleic acid chemically binds the metal particles. The catalysts are characterized and applied for hydrocracking of heavy oil. The well dispersed catalysts promoted the asphaltene and sulfur conversion activities, increasing the yield of the liquid product. Experimental results indicated that the bimetal can be effective if the metals are chemically bound to form a single catalyst [146]. An oil soluble nickel compound was decomposed for 2 h at 425 8C containing LiaoHe atmospheric residue (LHAR) with elemental sulfur. Catalyst concentration, pressure and reaction

temperature significantly affect the yield of the light oil and the coke formation [147]. Co–Mo bimetallic or mono metallic catalysts were prepared by layered coating with ammonium cobalt molybdate (synthesized by precipitation method) and oleic acid. The experimental study indicates that these catalysts are highly active toward asphaltenes and sulfur conversion [146]. Water-soluble dispersed catalysts Oil soluble catalysts show very high activities due to ease dispersion in the feeds and inhibiting coke formation. However, their synthesis cost and catalyst recovery hinder their development for slurry-phase hydrocracking process. To reduce the cost of the oil soluble catalysts, water soluble and inexpensive inorganic compounds have been developed as catalysts. When using a water soluble catalyst, pretreatments such as dispersion, emulsion and dehydration are needed. It is important to recycle this catalyst if it is used at more than thousands ppm. Phospho-molybdic acid and ammonium molybdenum are two typical types of water soluble catalysts. Water soluble catalysts are prepared by dissolving metal salt in solvent and then mixed with feeds to form an emulsion. Dehydration and sulfurization are performed in subsequent steps before the catalysts react with the feeds in the reactor. In Table 10, the activities of various watersoluble catalysts are presented. Along with the feed, a metal compound, heteropoly acid and water were placed in a reactor. When the metal compound was added, it became an organometllic compound. The organometallic compound and heteropoly acid had a synergistic effect on catalytic activity [156,157]. A specific P/Mo ratio catalyst was prepared by the Exxon Research and Engineering Company using an aqueous solution of phosphomolybdic acid and phosphoric acid [151–154,159,160]. The catalyst was pretreated with H2S to form a solid molybdenum sulfide and phosphorus for hydrocracking of heavy oil, coal and VR. The molybdenum compound was dissolved in aqueous ammonia solution for form water soluble ammonium molybdate. Next, the H2S gas was passed into that solution. Some of the molybdenum dissolved, and some of the solid molybdenum oxysulfide was separated out. The removal of ammonia is crucial for the catalytic activity. The aqueous phase showed significantly improved catalytic activity due to multistage sulfide formation [161–165].

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

21

Table 10 Water soluble dispersed catalysts for slurry bed processes. Licenser

Catalyst components

Feed

Amount of catalyst

Result

Ref.

Chevron Inc.

Mo, Ni oxide with aqueous ammonia

Athabasca VR 60 wt% VGO 40 wt%

4–10 wt% MoO3 with aqueous ammonia to form a mixture

Sulfur, nitrogen and metal removal > 98 wt%

[148–150]

Exxon Research and Engineering Co.

Phospho molybdic acid ammonium hepta-molybdate molybdenum oxalate Ni and Mo multimetallic catalyst

Arabian VR or Cold Lake crude oil Arab Light VR

Coke yield is low

[151–153]

High HDM activity

[150,154]

Nickel carbonate ammonium dimolybdate ammonium metatungstate

Low sulfur diesel oil

0.2–5 wt% Solid Mo and P containing catalyst Ratio of Ni and Mo varied from 0.1 to 10 Bulk multimetallic catalyst

High HDS, HDN activity

[155]

Universal Oil Products Co

Mo, V and Fe metal oxide or salt and heteropoly acid

Lloydminster VR

Solid, non-colloidal catalyst

60–65 wt% conversion, 1 wt% coke yield

[156,157]

PetroChina Company Limited

Ni, Fe, Mo and Fe–Co liquid catalyst

Karamay AR

Highly dispersed multimetallic catalyst

80–90 wt% conversion, 1 wt% coke yield

[158]

Anion-modified metal promoted iron based ionic liquids or liquid catalysts are used for hydrocracking heavy oil and VR. The catalyst is prepared via precipitation using an iron salt. Catalyst modification is possible by changing the active metal, for example nickel, molybdenum, cobalt, tungsten, palladium, platinum or its mixtures [166]. Bimetallic and multimetallic water soluble catalysts have been developed by the Fushun Research Institute of Petroleum and Petrochemicals. These catalysts have a high activity and coke formation resistivity (<1 wt% coke formation). When AR and VR were treated with Mo–Ni catalyst 70 wt% and 60 wt%, distillates (<500 8C) were obtained, respectively. High yields, i.e. 75 wt% and 70 wt% of middle distillates were also obtained from Liaohe atmospheric residue and VR from Saudi Arabian light crude, respectively [167]. Multimetal water soluble catalysts were prepared using various metal precursors such as sodium molybdate, nickel nitrate and iron nitrate. The catalyst evaluation results suggest that the multimetal composites tend to inhibit coke. A catalyst characterization study indicates that the reaction condition and catalyst pretreatment procedure significantly affect the catalyst dispersion [168]. Kamaya AR was also hydrocracked by a multimetal catalyst in a slurry-bed reactor. The hydrocracked oil was recycled back into fresh catalyst, and full conversion was observed [169]. VR derived from Gudao crude oil was hydrocracked in presence of several water soluble inorganic and oil soluble catalysts. Water soluble ammonium heptamolybdate (AHM), ammonium phosphomolybdate (APM), ammonium tetrathiomolybdate (ATM) and oil soluble molybdenum lithiocarboxylate (MoDTC), molybdenum lithiophosphate (MoDTP) showed more hydrocracking activity when it used in a high dispersive method [170]. Sulfur and phosphorus strongly influence the hydrocracking performance. In presence of phosphorus, external addition of sulfur increases the catalytic activity. Below 240 8C, the hydrogen sulfide produced in a reactor accelerates the catalytic activity. The phosphorous interacts with vanadium to improve the removal of vanadium from the product. Therefore, adding of phosphorus prevents the deactivation caused by the decomposition of vanadium [171]. A water-soluble iron and sulfurized nickel catalyst was synthesized and employed with LiaoHe VR (LHVR) feedstock. High dispersion enhanced the desired product by decreasing the interfacial tension between the feedstock and precursor. The dispersion could be generated using a high stirring speed [172,173]. However, to improve selectivity, the chemical composition of the catalyst is essential. Generally, the formulation of the active phases of Mo or Co–Mo catalyst is more effective at the top bed of the reactor, while Ni–Mo (Ni–W) formulations have a good

activity for hydrogenation and hydro-denirogenation (HDN) reactions. In all of the above process, i.e. the solid powder, water-soluble and oil-soluble processes, if a high concentration of active metal is used for hydrocracking, then the quality of the product is high, but the process becomes costlier. Therefore, recycling the catalysts is necessary to reduce the cost of this process. Hydrocracking reaction mechanisms Reaction mechanisms for hydrocracking of heavy oil or VR are currently being researched. There are few studies on real reaction mechanisms in the literature, and those that exist are limited to asphaltenes in VR hydrocracking [173]. Some studies have reported that hydrocracking of heavy oil is affected by reaction conditions such as temperature, initial H2 pressure and H2S partial pressure [174–176]. Hydrocracking of heavy oil not only depends on the catalytic sites (acid/base and metal) but is also affected by physical processes such as diffusion into the pores, adsorption on the surface, surface reactions on the catalytic active sites, desorption and diffusion of products. These processes are controlled by the textural properties of the catalyst. Hydrocracking of the heavy oil (particularly asphaltenes) occurs mainly through the carbonium ion mechanism (shown in Scheme 1). Carbonium ions are stabilized by reacting with either a parent molecule or interacting with another carbonium ion. Carbonium ions either fragment the C–C bond to form smaller stable product fractions (gas, or saturated compound) or react with olefinic compounds to form larger molecules (resins). Carbonium olefin molecules may undergo rearrangement (isomerization reaction) and hydrogenation to form saturated compounds. Mechanism of hydrodemetalation (HDM) and the role of H2S in the hydrocracking of heavy oil are limited due to the difficulty of complicated transition metal analyses [177]. Recently, an HDM reaction mechanism on sulfided catalysts was proposed. Hydrodemetalation of V and Ni involves the adsorption and hydrogenation of a transition metal complex to form the corresponding chlorine structure (one of the double bonds of pyrrol), which is hydrogenated [53,70,152]. However, H2S partial pressure creates Brønsted acid sites that facilitate adsorption and hydrogenation, conferring significant flexibility in the metal ligand and diminishing the stability of the transition metal complex. Based on this study, increasing the amount of H2S did not inhibit the HDM and hydrodeasphalte (HDAs) processes. However, the hydrodesulfurization (HDS) and HDN processes were considerably inhibited. Another effect of H2S on HDM has also been reported in various reports [178–180]. The reaction study revealed

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

22

Asph-R + H+ (acidic site)

Asph-R+ (carbonium ion) + H-

Asph + R1H

(i)

Aromatic (asphaltene) fraction + alkyle aliphatic chain

Asph

+ H+ (acidic site)

Pressure H2

MAL Cracking isomerization

MAL + R2H

(ii)

AN + R 3 H

(iii)

AN+ + HAromatization AR1 + R4H

(iv)

Smaller hydrocarbon HH-

+ H+ + Asph-R+

H2 Asph-RH

(v) (vi)

Asph = asphaltene or fused aromatic ring, R = alkyl chain, AN = hydroaromatic (naphthanic ring), and MAL = maltene Scheme 1. Proposed reaction mechanism for vacuum residue hydrocracking.

that the light gases, oil (saturates, aromatic), maltenes (saturates, aromatics, resin), asphaltenes and coke forms bond with the central transition metal atom (Ni or V) and therefore weaken the metal–N bond. Presence of –SH groups enhances the cracking of the asphaltene molecule or HDAs. Therefore, complex hydrocarbon molecules compete with several instantaneous parallel reactions (hydrotreating, hydrocracking, isomerization or alkylation, dehydrogenation, cyclization, etc.) [181–184]. Current and future developments In next few years, crude oil will be heavier due to high contents of impurities, like nitrogen, sulfur and metal. Refineries must improve the process technology used for hydrocracking of heavy feeds into valuable environmentally friendly products. Currently, fixed-bed, moving-bed, expanded-bed or ebullated-bed reactors are available for upgrading the heavy oils and VR. Moreover, the slurry-phase hydrocracking process is attractive when combined with the existing technology and product price structure. Heavy oil and VR contain complex molecules that pose numerous problems during up gradation. To upgrade these feeds, the process technology, various related factors such as properties of the feeds, catalyst activity and selectivity, chemical kinetic parameters, operating conditions, and contact time are important factors for achieving a high yield of the selected product. The main challenge involves combining these aspects at reasonable capital costs. During the hydrocracking process, the catalyst should tolerate metal and other impurities possesses in feeds as well as exhibiting high performance (activity, selectivity, stability and regenerability) and being cost effective. These are the main challenges for refineries. Some integrated processes (Shell’s Hycon System, Chevron’s OCR System, and Axens/IFP’s Hyvahl System) have been developed and commercialized. However, in fixed-bed processes, online catalyst replacement is preferable to a batch mode reactor, but this

process cannot handle heavier oils and higher metal impurities; much improvement is needed in reactor design and operation conditions. An ebullated-bed process shows more selectivity, high conversion of feeds, high liquid yield and relatively low hydrogen consumption. However, the back mixing of the reactants, high operating costs, high investment and low reactor efficiency are the main hurdles for hydrocracking of VR. Before slurry-phase processes commercialized, some impediments must be overcome. The main steps include optimizing the reaction conditions, lowering the reactor design cost, and using highly active and selective catalysts. The surface area, pore diameter, particle size, metal compositions and components, and metal particle distribution determine the activity and selectivity of the catalyst. The catalysts are also reasonably price having high mechanical strength and are recyclable. Hence, some attention must be paid to catalyst design. In industry, catalysts based on alumina or silica alumina must be exploited. In the near future, the VR upgrading technologies are likely to combine various hydroprocessing technologies with other processes, such as the thermal processes and solvent de-asphalting processes. In the slurry-phase process, use of pure hydrogen is also an important issue, as it makes the process more costly. Hydrogen gas should be replaced by other hydrogen sources. Conclusions The demand of transportation fuels and petrochemical applications are rapidly increasing. Unlike limited amount of traditional light petroleum resources, low quality heavy oils and VR are abundant. Therefore, techniques, which can upgrade heavier petroleum resources, need to be developed. One of the most efficient methods for such purpose is catalytic hydrocracking. The slurry-phase hydrocracking process is effective and is an attractive option for overcoming the limitations associated with other technologies. The main objective is to treat the heavier

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

residue to obtain high quality products, low boiling point liquid with low viscosity. For hydrocracking processes, coke formation can be suppressed in hydrogen rich atmosphere, and therefore, catalytic life time can be prolonged with high catalytic activity. Hydrocracking catalyst performance can be controlled by types of supports, composition, preparation procedure, and process conditions. Therefore, a strategic catalyst development is essential to obtain high activity and selectivity for hydrocracking of VR and other heavy oils. Simultaneously, deactivation caused by metal impurities and physical damages should also be considered. In addition, life span of the catalyst may be extended by changing its textural properties. In slurry-phase type processes for heavy oil and VR hydrocracking, three broad catalytic phases were developed: heterogeneous supported metal catalyst, water soluble catalyst, and oil soluble homogeneously dispersed catalysts. The heterogeneous solid powder catalysts have low catalytic activity due to their lower dispersion in the reactor and solid particle formation in the bottom of the reactor. However, the homogeneous catalysts are highly dispersed and have a relatively bigger surface area to volume ratio. Therefore, they show high catalytic activity, which is resulted in high quality product formation. Although, this type of catalyst is suitable for slurry-phase hydrocracking of heavy oil and VR, limitations lies in mass synthesis and separation of catalysts need to be overcome in order to utilize the technology for heavy oil upgrading. Acknowledgments We would like to acknowledge the financial support from the R&D Convergence Program of MSIP (Ministry of Science, ICT and Future Planning) and ISTK (Korea Research Council for Industrial Science and Technology) of Republic of Korea (Grant B551179-1207-00). The authors also acknowledge to KIIT University for granting of study leave.

References [1] M.J. Hutzler, S. Sitzer, P.D. Holtberg, J. Conti, J.M. Kendell, A.S. Kydes, Annual Energy Outlook 2003 with projection to 2025, 205, 85, The United States Energy Information Administration, US Department of Energy, Washington, DC, 2003p. 267. [2] J. Chang, N. Tsubaki, K. Fujimoto, Fuel 80 (2001) 1639. [3] R. Yoshida, M. Miyazawa, H. Ishiguro, S. Ito, K. Haraguchi, H. Nagaishi, H. Narita, T. Yoshida, Y. Maekawa, Y. Mitarai, Fuel Process. Technol. 51 (1997) 195. [4] R. Yoshida, M. Miyazawa, T. Yoshida, H. Narita, Y. Maekawa, Fuel 75 (1996) 99. [5] R. Yoshida, T. Yoshida, H. Narita, Y. Maekawa, Fuel 65 (1986) 425. [6] P.R. Bauquis, A Reappraisal of Energy Supply and Demand in 2050, The Institute of Energy Economics, Japan, July, 2002, http://eneken.ieej.or.jp/en/outlook/. [7] S. Dehkissia, F. Larachi, E. Chornet, Fuel 83 (2004) 1323. [8] A. Matsumura, T. Kondo, S. Sato, I. Saito, Fuel 84 (2005) 411. [9] J. Lee, S. Hwang, J.G. Seo, U.G. Hong, J.C. Jung, I.K. Song, J. Ind. Eng. Chem. 17 (2011) 310. [10] M.R. Rada, A. Rashidi, L. Vafajoo, M. Rashtchi, J. Ind. Eng. Chem. 20 (2014) 4298. [11] J. Shah, M.R. Jan, Adnan, J. Ind. Eng. Chem. 20 (2014) 3604. [12] M. Bender, Resour. Conserv. Recycl. 30 (2000) 49. [13] M.F. Demirbas, Energy Sources, Part A 28 (2006) 1181. [14] D.W. Lee, B.R. Yoo, J. Ind. Eng. Chem. 20 (2014) 3947. [15] Z. Lei, L. Wu, L. Gao, M. Liu, H. Shui, Z. Wang, S. Ren, J. Ind. Eng. Chem. 19 (2013) 1421. [16] J. Park, S.A. Ali, K. Alhooshani, N. Azizi, J. Miyawakia, T. Kim, Y. Lee, H.S. Kim, S.H. Yoon, I. Mochida, J. Ind. Eng. Chem. 19 (2013) 627. [17] G. Wanga, K. Zhang, P. Liu, H. Hui, Y. Tan, J. Ind. Eng. Chem. 19 (2013) 961. [18] M. Bayat, M. Hamidi, Z. Dehghani, M.R. Rahimpour, J. Ind. Eng. Chem. 20 (2014) 858. [19] L. Atkins, T. Higgins 3, C. Barnes, Heavy Crude Oil Global Analysis and Outlook to 2030, Hart Energy Consulting Report, Houston, TX, USA, 2010. [20] D. Vartivarian, H. Andrawis, Oil Gas J. 104 (2006) 52. [21] J.Z. Ring, Abundantly and Securely Yours, Quarterly Newsletter of the NCUT, Secondary Upgrading and Refining, 2000 Group # 6, 5, Spring. [22] F.E. Biasca, R.L. Dickenson, E. Chang, H.E. Johnson, R.T. Bailey, D.R. Simbeck, In Upgrading Heavy Crude Oils and Residue to Transportation Fuel: Technology Economics and Outlook, Phase 7, Garland R. Report Coordinator, SAF Pacific Inc. Eng. & Economic Consultant, 2003.

23

[23] H. Shen, Z. Ding, R. Li, Proc 15th World Petroleum Congress, vol. 2, Beijing, China, (1998), p. 907. [24] K.E. Rose, Hydrocarbon Process. 7 (1971) 85. [25] M.R. Gray, Upgrading Petroleum Residues and Heavy Oils, CRC Press, New York, 1994. [26] J.G. Speight, The Chemistry and Technology of Petroleum, CRC Press, New York, 2006. [27] S. Rahmani, W. McCaffrey, M.R. Gray, Energy Fuels 16 (2001) 148. [28] J. Ancheyta, G. Centeno, F. Trejo, G. Marroquı´n, Energy Fuels 17 (2003) 1233. [29] J. Schmidt, http://findarticles.com/p/articles/mim3159/is12226/15979981, 2010. [30] W. Kotowski, W. Fechner, B. Lucke, Przem. Chem. 2 (1999) 51. [31] R.R. Jacob, Hydrocarbon Process. 9 (1971) 132. [32] S.D. Carlo, B. Janis, Chem. Eng. Sci. 47 (1992) 2695. [33] J.G. Speight, The Chemistry and Technology of Petroleum, 3rd ed., Marcel Dekker, New York, 1999. [34] R. Quann, R.A. Ware, C.W. Hung, J. Wei, Adv. Chem. Eng. 14 (1988) 95. [35] C. Leyva, M.S. Rana, F. Trejo, J. Ancheyta, Ind. Eng. Chem. Res. 46 (2007) 7448. [36] S. Sugianto, R.M. Butler, J. Can. Pet. Technol. 29 (1990) 78. [37] A.N. Sawarkar, A.B. Pandit, S.D. Samant, J.B. Joshi, Can. J. Chem. Eng. 85 (2007) 1. [38] J.G. Speight, The Desulfurization of Heavy Oils and Residua, Marcel Dekker Inc., New York, 2000. [39] S.L. Chen, S.S. Jia, Y.H. Luo, S.Q. Zhao, Fuel 73 (1994) 439. [40] V.A. Adewusi, B. Ademodi, T. Oshinowo, Fuel Process. Technol. 27 (1991) 21. [41] C.W. Curtis, K.J. Tsai, J.A. Guin, Fuel Process. Technol. 16 (1987) 71. [42] A. Billon, F. Morel, J.P. Peries, 15th World Petroleum Congress, Beijing, China, 1997. [43] R.L. Dickenson, F.E. Biasca, B.L. Schulman, H.E. Johnson, Hydrocarbon Process. 76 (1997) 57. [44] T. Tsujino, Fuel Energy Abstr. 37 (1996) 183. [45] R.V. Pindoria, A. Megaritis, I.N. Chatzakis, L.S. Vasanthakumar, S.F. Zhang, M.J. Lazaro, Fuel 76 (1997) 101. [46] O. Holopainen, Bioresour. Technol. 46 (1993) 125. [47] F. Gulli, Energy Policy 23 (1995) 647. [48] B.G. Houk, Fuel Energy 37 (1996) 176. [49] A. Tokarska, Fuel 75 (1996) 1094. [50] F.R. Reinoso, P. Santana, E.R. Palazon, M.A. Diez, H. Marsh, Carbon 36 (1998) 105. [51] E. Furimsky, Fuel Process. Technol. 67 (2000) 205. [52] B.I. Zuba, Hydrocarbon Process. 10 (1998) 132. [53] J.W. Scott, A.G. Bridge, Adv. Chem. Ser. 103 (1971) 113. [54] J.W. Scott, N.J. Patterson, Proc. 7th Wld. Petrol. Congr. 4, 1967, p. 97. [55] G.L. Farrar, Oil Gas J. 71 (1973) 25. [56] D.H. Stormont, Oil Gas J. 66 (1968) 104. [57] J. Cherzer, A.J. Gruia, Hydrocracking Science and Technology, Marcel Dekker, New York, 1996. [58] E. Furimsky, Appl. Catal. A 46 (1988) 177. [59] F.M. Dautzenberg, J.C.D. Deken, Catal. Rev. Sci. Eng. 23 (1984) 421. [60] G.N. Sarkar, Advanced Petroleum Refining, 1st ed., Khanna Publishers, New Delhi, 1998. [61] J.W. Gosselink, Cattech 2 (1998) 127. [62] S. Kressmann, F. Morel, V. Harle, S. Kasztelan, Catal. Today 43 (1998) 203. [63] B.E. Reynolds, R.W. Bachtel, K. Yagi, Presented at the 1992 NPRA Annual Meeting, New Orleans, LA, 1992. [64] J. Ancheyta, J.G. Speight, Reactors for Hydroprocessing of Heavy Oil and Residual, Taylor and Francis, New York, 2007 (Chapter 6). [65] E. Furimsky, F.E. Massoth, Catal. Today 52 (1999) 381. [66] L.E. Gardner, S.G. Kukes, Hydrofining Employing a Support Material for Fixed Beds, 1989 US 4828683. [67] J. Ramirez, M.S. Rana, J. Ancheyta, J.G. Speight, Characteristics of Heavy Oil Hydroprocessing Catalysts, Taylor and Francis, New York, 2007 (Chapter 6). [68] B.M. Perry, G.W. Pukanic, J.A. Ruether, Prepr. Pap. – Am. Chem. Soc. Div. Fuel Chem. 34 (1989) 1206. [69] L.K. Doraiswamy, Catal. Rev. Sci. Eng. 10 (1974) 177. [70] Y.W. Chen, Ind. Eng. Chem. Res. 29 (1990) 1830. [71] W. Liang, Heavy Oil Chemistry, Petroleum University Press, Shandong, 2000. [72] M.M.B. Klaus, H. Altgelt, Composition and Analysis of Heavy Petroleum Fractions, M. Dekker Ed., New York, 1994. [73] ASTM Method D2887-97, Test Method for Boiling Range Distribution of Petroleum Fractions by Gas Chromatography, Annual Book of ASTM Standards, vol. 05.02, American Society for Testing and Materials, Philadelphia, PA, 1997. [74] ASTM Designation D-5307-97, Annual Book of ASTM Standards, vol. 05.02, ASTM, Philadelphia, PA, 2002. [75] J.C. Raia, D.C. Villalanti, M. Subramanian, B. Williams, J. Chromatogr. Sci. 38 (2000) 1. [76] ASTM Method D2892-95, Test Method for Distillation of Crude Petroleum, Annual Book of ASTM Standards, vol. 05.02, American Society for Testing and Materials, Philadelphia, PA, 1996. [77] ASTM Designation D-2892-03.2003, Annual Book of ASTM Standards, vol. 05.02, ASTM, Philadelphia, PA, 2003. [78] M. EspinosaPen, Y. FigueroaGomez, F. JimenezCruz, Energy Fuels 18 (2004) 1832. [79] D.C. Villalanti, J.C. Raia, J.B. Maynard, in: R.A. Meyers (Ed.), High temperature Simulated Distillation Applications in Petroleum Characterization, Encyclopedia of Analytical Chemistry, John Wiley & Sons Ltd., Chichester, 2000. [80] J.G. Speight, Catal. Today 98 (2004) 55. [81] M.S. Rana, J. Ancheyta, S.K. Maity, P. Rayo, Pet. Sci. Technol. 25 (2007) 201. [82] J. Ancheyta, M.S. Rana, E. Furimsky, Catal. Today 109 (2005) 3. [83] M.S. Rana, J. Ancheyta, P. Rayo, Catal. Today 104 (2005) 86. [84] U. Graeser, G. Eschet, R. Holighnaus, in: Proceedings of the Refining Department, American Petroleum Institute, San Diego, 1986.

24

R. Sahu et al. / Journal of Industrial and Engineering Chemistry 27 (2015) 12–24

[85] W. Dohler, K. Kretschmar, L. Merz, Div. Pet. Chem. Am. Chem. Soc. 32 (1987) 484. [86] F. Wenzel, K. Kretschmar, Veba-Combi-Cracking Process Status and Future Trends Oil Sands Our Petroleum Future, Alberta Research Council, Edmonton, Alberta, 1993. [87] http://www.pemex.com/files/content/Memoria-2009.pdf, 2011 (accessed 04.03.11). [88] R.L. Dickenson, B.L. Schulman, F.E. Biasca, H.E. Johnson, Paper AM-96-57, NPRA Annual Meeting, San Antonio, 1996. [89] B. Chuetze, H. Hofmann, Hydrocarbon Process. 62 (1984) 75. [90] R. Bearden, Hydroconversion of Heavy Hydrocarbons, 1979 US 4134825. [91] R. Bearden, Catalyst for the Hydroconversion of Heavy Hydrocarbons, 1980 US 226742. [92] C.J. Mart, E.G. Ellis, D.S.J. McCaffrey, PETROTECH 6th International Petroleum Conference and Exhibition, New Delhi, India, 2005. [93] R. Bearden, MICROCAT-RC: Technology for Hydroconversion Upgrading of Petroleum Residues, Division of Petroleum Chemistry, American Chemical Society, San Francisco, CA, 1997. [94] L.C. Castaneda, Fuel 100 (2012) 110. [95] R. Montanari, S. Rosi, N. Panariti, M. Marchionna, A. Delbianco, Convert Heaviest Crude & Bitumen Extra-clean Fuels via EST-Eni Slurry Technology in NPRA Annual Meeting, San Antonio, USA, 2003. [96] D. Sanfilippo, Bottom of the Barrel Technology Within Refining Extracting Additional Value from Oil Feedstocks Using EST Technology, WTG Webinar Connected from San Donato Milanese, Italy, 2009. [97] R. Montanari, M. Marchionna, N. Panariti, WO056946, 2004. [98] M. Marchionna, A. Delbianco, N. Panariti, US 0089636, 2003. [99] G. Rispoli, Heavy Oil Upgrading GE Oil & Gas Annual Meeting, Florence, Italy, 2009. [100] G. Drago, J. Gultian, J. Krasuk, Div. Pet. Chem. Am. Chem. Soc. 35 (1990) 584. [101] R.B. Solari, Presented at the NPRA Annual Meeting, San Antonio, 1990. [102] Headwaters Incorporated Announces Successful Commercial Implementation of the HCAT, Heavy Oil Upgrading Technology at the Neste Oil Porvoo Refinery, Headwaters Incorporated News, Bulletin, 2011. [103] M.K. Bisaria, N.N. Bakhsh, R. Ranganathan, AIChE, Spring National Meeting, vol. 90b, Orlando, 1990. [104] M. Seko, NPRA Annual Meeting, San Antonio, TX, 1988. [105] HCAT Technology-innovative Process & Catalyst For Heavy Oil Upgrading, 2011. http://www.htigrp.com (retrieved 31.01.11). [106] G. Lunin, L.W. Chambers, B.I. Parsons, Technical Meeting/Petroleum Conference of the South Saskatchewan Section, Regina, 1985. [107] B. Pruden, G. Muir, M. Skipek, Oil Sands Our Petroleum Future, Alberta Research Council, Edmonton, Alberta, Canada, 1993. [108] C.P. Khulbe, R. Ranganathan, B.B. Pruden, US 4299685, 1981. [109] A.E. Silva, H.K. Rohrig, A.R. Dufresne, Oil Gas J. 6 (1984) 81. [110] http://www.pemex.com/files/content/Memoria-009.pdf, 2011 (accessed 04.03.11). [111] M. Seko, K. Kato, Y. Shohji, Presented at the NPRA Annual Meeting, 1988. [112] M. Seko, N. Ohtake, AIChE Symp. Ser. 273 (1989) 5. [113] M.S. Rana, V. Sa´mano, J. Ancheyta, J.A.I. Diaz, Fuel 86 (2007) 1216. [114] M. Yasumuro, T. Okui, N. Okuyama, M. Tamura, T. Shigehisa, CA 2426374, 2003. [115] J. Yves, M. Davidson, J.F.L. Page, US 4285804, 1981. [116] S. Zhang, D. Liu, W. Deng, G. Que, Energy Fuels 21 (2007) 3057. [117] L.I. Chuan, S.H.I. Bin, C.U.I. Min, S. Hongyan, Q. Guohe, Fuel Chem. Technol. 35 (2007) 407. [118] M. Kouzu, Y. Kuriki, K. Uchida, Energy Fuels 19 (2005) 25. [119] I. Mochida, X.Z. Zhao, K. Sakanishi, Ind. Eng. Chem. Res. 334 (1990) 334. [120] A. Matsumura, S. Sato, T. Kondo, I. Saito, W.F.d. Souza, Fuel 84 (2005) 417. [121] C. NguyenHuya, H. Kweon, H. Kim, D.K. Kim, D. Kim, S.H. Ohb, E.W. Shin, Appl. Catal. A: Gen. 447 (2012) 186. [122] R. J. Bearden, C. L. Aldridge, US4067799, 1978. [123] S. A. Fouda, J. F. Kelly, CA1276902, 1990. [124] R.K. Lott, T. Cyr, L.K. Lee, CA 2004882, 1991. [125] A.K. Jain, B.B. Pruden, US 4999328, 1991. [126] T.T. Viet, J. Lee, J.W. Ryu, I. Ahn, C. Lee, Fuel 94 (2012) 556. [127] T. Tugsuu, S. o Yoshikazu, B. Enkhsaruul, D. Monkhoobor, Adv. Chem. Eng. Sci. 2 (2012) 402.

[128] M.J. Fesharaki, M. Ghashghaee, R. Karimzadeh, J. Anal. Appl Pyrolysis (2013), http://dx.doi.org/10.1016/j.jaap.2013.03.009. [129] H. Puroon, J.L. Pinilla, C. Berrueco, J.A.M. Fuente, M. Millaan, Energy Fuels 27 (2013) 3952. [130] M. Rahimi Rad, A.M. Rashidi, L. vafajoo, in: Proceedings of the 4th International Conference on Nanostructures (ICNS4), Kish Island, I.R. Iran, 12–14 March, 2012. [131] A.D. Bianco, N. Paanriti, S.D. Carlo, J. Elmouchnino, B. Fixari, P.L. Perchec, Appl. Catal. A 94 (1993) 1. [132] C. Liu, J. Zhou, G. Que, W. Liang, Y. Zhu, Fuel 73 (1994) 1544. [133] I. Watanabe, M. Otake, M. Yoshimoto, K. Sakanishi, Y. Korai, I. Mochida, Fuel 81 (2002) 1515. [134] S. Zhang, W. Deng, H. Luo, D. Liu, G. Que, Energy Fuels 22 (2008) 3583. [135] R.J. Bearden, C.L. Aldridge, US 4226742, 1980. [136] C.L. Aldridge, R.J. Bearden, US 4066530, 1978. [137] R.J. Bearden, C.L. Aldridge, US 4295995, 1981. [138] R.J. Bearden, C.L. Aldridge, US 4579838, 1986. [139] T. Cyr, L. Lewkowicz, B. Ozum, US 5578197, 1996. [140] O.P. Strausz, US 6068758, 2000. [141] H. Sheldon, US 4125455, 1978. [142] J.G. Gatsis, US 4194967, 1980. [143] O.P. Strausz, Fuel Energy Abstr. 37 (1996) 176. [144] R. Shen, H. Zhao, C. Liu, G. Que, Pet. Process. Petrochem. 29 (1998) 10. [145] Z.X. Dong, Ind. Catal. 11 (2003) 27. [146] S.G. Jeon, J.G. Na, C.H. Ko, K.B. Yi, N.S. Rho, S.B. Park, Energy Fuels 25 (2011) 4256. [147] Z. Shuyi, D. Wenan, L. Hui, L. Dong, Q. Guohe, Energy Fuels 22 (2008) 3583. [148] J. Chabot, K. Chen, P.C. Leung, B.E. Reynolds, US 7214309 B2, 2007. [149] K. Chen, P.C. Leung, B.E. Reynolds, US 7238273 B2, 2007. [150] K. Chen, B.E. Reynolds, US 7396799 B2, 2008. [151] R.J. Bearden, C.L. Aldridge, F.X. Mayer, J.H. Taylor, W.E. Lewis, US 4740489, 1988. [152] C.L. Aldridge, R.J. Bearden, US 5039392, 1991. [153] R.J. Bearden, C.L. Aldridge, US 4637871, 1987. [154] Z. Hou, R.J. Bearden, D.F. Thomas, US 6712955, 2004. [155] R.A. Demmin, K.L. Riley, S.L. Soled, S. Miseo, US 6620313 B1, 2003. [156] J.G. Gatsis, US 5474977, 1995. [157] J.G. Gatsis, US 5288681, 1994. [158] G. Que, C. Men, C. Meng, A. Ma, J. Zhou, W. Deng, Z. Wang, US 6660157 B2, 2003. [159] R.J. Bearden, US 4637870, 1987. [160] R.J. Bearden, US 4740295, 1988. [161] J. Lopez, J.D. McKinney, E.A. Pasek, US 4557821, 1985. [162] J. Lopez, E.A. Pasek, US 4710486, 1987. [163] J. Lopez, E.A. Pasek, A.V. Cugini, US 4762812, 1988. [164] J. Lopez, E.A. Pasek, US 4824821, 1989. [165] J. Lopez, E.A. Pasek, US 4857496, 1989. [166] B.P. Pelrine, A.G. Comolli, L.K. Lee, US 6139723, 2000. [167] X. Wang, Y. Li, Z. Zhang, Pet. Refin. Eng. 30 (2000) 50. [168] C. Guan, Z. Wang, G. Que, Acta Pet. Sin. 20 (2004) 75. [169] J. Zhou, W. Deng, D. Liu, S. Liang, G. Que, Acta Pet. Sin. 17 (2001) 82. [170] C. Liu, G. Que, W. Liang, Y. Zhu, Pet. Refin. 24 (1993) 57. [171] S. Kushiyama, R. Aizawa, S. Kobayashi, Y. Koinuma, I. Uemasu, H. Ohuchi, Appl. Catal. 63 (1990) 279. [172] H. Luo, W. Deng, J. Gao, W. Fan, G. Que, Energy Fuels 25 (2011) 1161. [173] R. Tanaka, J.E. Hunt, R.E. Winans, P. Thiyagarajan, S. Sato, T. Takanohashi, Energy Fuels 17 (2003) 127. [174] T. Trejo, J. Ancheyta, Catal. Today 109 (2005) 99. [175] M.S. Rana, J. Ancheyta, P. Rayo, S.K. Maity, Fuel 86 (2007) 1263. [176] S.A. Quader, G.A. Hill, Ind. Eng. Chem. Process Des. Dev. 8 (1969) 450. [177] J.P. Janssens, G. Elst, E.G. Schrikkema, A.D.V. Langeveld, S.T. Sie, J.A. Moulijn, Recl. Trav. Chim. Pay Bas. 115 (1996) 465. [178] R.L.C. Bonne, P.V. Steenderen, J.A. Moulijn, Appl. Catal., A 206 (2001) 171. [179] L.A. Rankel, Prepr. Am. Chem. Soc., Div. Pet. Chem. 26 (1981) 689. [180] R.A. Ware, J. Wei, J. Catal. 93 (1985) 122. [181] E. Mielczarski, S.B. Hong, R.J. Davis, M.E. Davis, J. Catal. 134 (1992) 359. [182] R.J. Davis, E.A. Derouane, Nature 349 (1991) 313. [183] I.M. Seirvert, A.P. Claerbout, N. Blom, E.G. Derouane, J. Catal. 164 (1996) 347. [184] K. Hashimoto, T. Masuda, H. Kashihara, Appl. Catal. 75 (1991) 331.