Thermodynamic analysis of in-situ hydrogen from hot compressed water for heavy oil upgrading

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 4 ( 2 0 1 9 ) 2 7 6 7 1 e2 7 6 8 4

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Thermodynamic analysis of in-situ hydrogen from hot compressed water for heavy oil upgrading Morteza Hosseinpour a,*, Amir Hossein Hajialirezaei a, M. Soltani b,c,d,e, Jatin Nathwani e a

Renewable Energy Department, Niroo Research Institute (NRI), Tehran, Iran Department of Mechanical Engineering, K. N. Toosi University of Technology, Tehran, Iran c Advanced Energy Initiative Center, K. N. Toosi University of Technology, Tehran, Iran d Department of Earth & Environmental Sciences, University of Waterloo, Waterloo, Ontario, Canada e Waterloo Institute for Sustainable Energy (WISE), University of Waterloo, Waterloo, Ontario, Canada b

highlights

graphical abstract


Hydrogen (H2) production from hot compressed water (HCW) via partial oxidation of heavy oil was modeled by Aspen Plus software.
A sensitivity analysis was conducted to study the effect of the main operating parameters aimed to the H2 production.
Experiments were conducted in order

to

track

the

results

of

simulation.
The most thermodynamic favorable

operating

conditions

for

upgrading heavy oil in HCW were identified.

article info

abstract

Article history:

Due to many benefits of heavy oil upgrading in the green medium of hot compressed water

Received 4 May 2019

(HCW), the present study considers the thermodynamic analysis of in-situ hydrogen

Received in revised form

created by partial oxidation of light hydrocarbons (HC) in HCW. The aim is seeking the

22 July 2019

upgrading condition where light hydrocarbons create hydrogen (H2) and carbon monoxide

Accepted 26 August 2019

(CO) assisted by partial oxidation of light hydrocarbons. The formed CO collaborates in in-

Available online 30 September 2019

situ active hydrogen through water gas shift reaction (COþH2O4H2þCO2) which is more effective than external hydrogen for hydrogenation of heavy oil in HCW. Applying the

Keywords:

powerful capability of Aspen Plus®, i.e., sensitivity analysis, the effect of significant pa-

Hot compressed water (HCW)

rameters, such as temperature, pressure (water density), water to oil ratio, and oxygen (O2)

Heavy oil

to oil ratio are studied comprehensively in order to maximize the amount of active

Partial oxidation

hydrogen. The results indicate that higher temperatures and the amount of water (H2O/

* Corresponding author. E-mail addresses: [email protected], [email protected] (M. Hosseinpour). https://doi.org/10.1016/j.ijhydene.2019.08.223 0360-3199/© 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

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heavy oil) are two favorable factors to increase the contribution of active hydrogen, while the pressure is not a determinant factor at supercritical condition (P  25 MPa). The formation of methane is also decreased at high temperature which is desired for upgrading system. The higher amount of water implies more quantity of O2 since partial oxidation affords the enthalpy of auto-thermal reforming of HO. Hence there should be a compromise in the selected ratios of H2O/HC and O2/HC in HCW upgrading system. A set of experiments are conducted in order to compare the simulation and experimental results. Although the experimental results are established on kinetic data which also reflect the physical effect of HCW during HO upgrading, however, the thermodynamic study provides valued information, in agreement with experiments, that improves our understanding of HO upgrading in HCW with less coke. © 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Introduction The petroleum oil as feed for crude distillation columns of refineries has been steadily getting heavier and their sulfur and nitrogen content are increased as well, while the demand for lighter liquid oils is increasing in markets. Consequently, heavy petroleum such as bitumen, tar sand, and oil shale should be utilized [1,2] in the coming years. The use of these feeds leads to heavier products at the bottom of distillation columns, including atmospheric residue (AR) and vacuumdistilled residual (VR) [3]. Therefore, upgrading of these heavy products should be considered as well as economic evaluation of refinery plants that transform such low-grade feeds to valued lighter fuels. In this case, thermal cracking, catalytic cracking, and hydrocracking are the conventional processes for production of the lighter fuels from AR and VR residua which these products primarily meet or satisfy stringent environmental regulations [3e8]. From an industrial point of view, heavy oil upgrading can proceed via carbon rejection and hydrogen addition processes aiming to increase the hydrogen to carbon ratio (H/C) [1]. Hydroprocessing technologies use the expensive catalysts which easily be deactivated by coke and metal depositions. They also consume huge amounts of hydrogen come from methane-reforming units, costly operations of the refineries which release huge amount of CO2 to the atmosphere [1]. Therefore, other technologies that decrease the operational costs and improve the efficiency of heavy oil upgrading process have been studied in recent years. Several efforts have been made to create and develop heavy oil upgrading and improve recovery processes by investigating the catalyst and operating conditions of the system [9,10]. Schacht-Hernandez et al. studied the hydrotreatment of the heavy oil by liquid NieMo catalyst in bench-scale test. The results of this work indicated that liquid NieMo catalyst improved the crude oil properties and reduced the contamination such as nitrogen and sulfur contents. Better hydrogenation behavior and low coke formation was the result of this work [11]. Other investigations for upgrading the heavy oil such as gasification process in hot compressed water (HCW) conditions and use of catalyst have been studied focusing on operating parameters including operating conditions, presence of catalyst, feed

composition and residence time with the aim of improving the performance of system for hydrogen production [12e19]. Hence, upgrading of heavy oil process in HCW at extreme condition has been extensively studied due to its great potential for heavy oil upgrading and in-situ hydrogen production. If HCW provides the demanded hydrogen, this process will likely have to be green and economical. In-situ active hydrogen will be produced leading to the high-qualified lighter product with less coke [15e17]. On the other hand, by improving the reforming process and consequently, producing more hydrogen, the upgrading process for converting the heavy compound to the light valuable product will be efficient and can be economically justified. Several researches have considered reforming processes including partial oxidation, steam reforming and autothermal reforming for hydrogen production [18e23]. Water-gas shift reaction (WGSR) has also been applied for producing the in-situ hydrogen which will be used in the hydrogenation of heavy oil [17]. Recently, Huang et al. studied the hydrogen production from gasification of glucose with in-situ nickel nanoparticle catalyst at HCW conditions. The results show improved carbon gasification with the increasing of the hydrogen yield [11]. With respect to operating conditions, HCW, here water at operational condition than critical point (Tc > 647 K and Pc > 22.1 MPa) provides a good environment as an alternative for the heavy oil upgrading [24,25]. HCW easily dissolves light organic components in both liquid or gas form and disperses heavy fractions (such as asphaltene), which are the precursor of made coke [26]. HCW properties such as density and dielectric constant can be abruptly changed by variation of temperature and pressure which recognized it as a promising technology for hazardous waste treatment via oxidation in HCW, namely supercritical water oxidation (SCWO) [27e30], biomass conversion [9,16,31e34] and the synthesis of advanced nanomaterials [10,12,13,35e40]. Against the heavy oil upgrading in dry condition, HCW influences the phase behavior of heavy oil upgrading system by influence on solvation and dispersion which leads lighter liquid products and less coke [41]. HCW also provide a suitable condition to remove heteroatoms such as sulfur and nitrogen available in heavy oil which are precursor as environment pollutant during combustion. Timko et al. [42] studied the effective

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parameters on desulfurization of heavy oil upgrading in HCW. The results show that sulfur content will be reduced and average molecular weight will be decreased without rejecting carbon as coke products. In another study, Tan et al. [43] investigated the pyrolysis of heavy oil in presence of HCW and nitrogen. They reported that, regarding physical properties of HCW, pyrolysis in the HCW phase is faster than in oil phase and as a result, upgrading of HO increases effectively, while its chemical effect on the properties of equilibrium liquid products is minor. Hosseinpour et al. [44,45] studied the catalytic cracking of bottom product (vacuum residue) in HCW over different forms of iron oxide nano-catalyst. Their studies demonstrate the role of catalyst as oxygen donor with significant influence on qualification of lighter product as well as suppression in coke formation. Further, catalyst remained unchanged stable during the upgrading process (effect of HCW). WGSR and reverse WGSR from decomposition of formic acid (HCOOH) in HCW were also examined to reveal the essential factors for suppression of coke formation [46]. Upgrading heavy oil and residua in the presence of other hydrogen-donors is an innovative environmentally friendly approach, which has recently attracted considerable attention [47,48]. With regard to reforming processes, partial oxidation in HCW is another promising route for active hydrogenation of heavy oil by in-situ hydrogen via WGSR (COþH2O/H2þCO2). The required CO comes from the partial oxidation of light hydrocarbons which are miscible in HCW and easily access to the oxygen as soluble gas in HCW [46,49]. This technique is predominantly suitable for heavy oil and residua feeds which contain substantial amount of sulfur and heavy metals that impose challenges to the catalytic upgrading process like catalyst poisoning. Several studies have been reported on partial oxidation of hydrocarbons in HCW conditions. In Sato et al., studies [50,51] hydrogenation of heavy oil has been studied in HCW through the CO and CO2 created from partial oxidation followed by active hydrogen is produced via WGSR and hydrogenation of heavy oil proceeds. Alshamari et al. [52] studied the partial oxidation of n-hexane in HCW experimentally and the results of study demonstrate new promising routes for hydrogen production with the aim of in-situ hydrogenation of heavy hydrocarbons in a HCW reactor. The potential of producing hydrogen via reforming of heavy oil in HCW was studied in other work of Alshamari et al. [53] with hexadecane, as a heavy hydrocarbon model, in tubular flow reactor under operational condition of 525e605  C and 15e22 MPa. Results show the potential for a continuous process for hydrogen generation from heavy hydrocarbons in hot compressed water which minimizes the formation of solid carbonaceous. Therefore, partial oxidation process in HCW can eliminate the need for using the expensive catalysts or externally added the vast amount of hydrogen. In the field of simulation studies, we investigated the thermodynamic analysis and equilibrium compositions of the reaction system for producing the hydrogen by Aspen Plus software. Gibbs free energy minimization method was applied for determining the optimum conditions and also predicting the hydrogen yield and purity at the equilibrium condition [18,20,21,54,55]. For instance, Leal et al. studied the autothermal reforming (ATR) of impure glycerol for mapping the

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effect of different conditions including pressure, temperature, oxygen to glycerol molar ratio and water to glycerol molar ratio on product yield, particularly hydrogen [18]. Alshammari et al. investigated the thermodynamic analysis of hydrothermal gasification and partial oxidation of hexadecane by Gibbs reactor model under different parameters such as water to carbon ratio, oxygen to carbon ratio and etc. results of model validated by different reported results of modeling and also experimental data which resulted in a good agreement [54]. Therefore, simulations can be applied for obtaining the optimum conditions that maximum yield of hydrogen which are verified by experiment results or other modeling works. The aim of this paper is to assess the required hydrogen for in-situ hydrogenation of heavy oil from the partial oxidation of lighter compounds of heavy oil in HCW condition and therefore reach to better performance of the system. So, water is considered as source of hydrogen which is required for upgrading process. All simulation was done by Aspen Plus® which is reputable software in chemical engineering field. Aspen Plus is a market-leading process modeling tool for conceptual design, optimization, and performance monitoring for the chemical, polymer, specialty chemical, metals and minerals, oil and coal power industries. Aspen Plus software has largest database of pure component and phase equilibrium data for conventional chemicals, electrolytes, solids, and also polymers. Sensitivity analysis was performed to know the effect of the main operating parameters on hydrogen yield. The main operating parameters are included oxygen to hydrocarbon mole ratio, water to hydrocarbon mole ratio, temperature and pressure. Besides experimental results, this paper provides noteworthy information about optimum conditions for upgrading the heavy oil in HCW with better efficiency in the upgrading process.

Experiment and process model description Upgrading procedure The studied heavy oil is the heaviest cut of oil refinery, namely vacuum residue (VR) where obtained from the bottom of the vacuum distillation tower of Tehran Refinery, Iran. This oil cut is ultra-heavy oil with boiling point higher than 550  C at ambient pressure. The VR feed contains 79 wt% of maltene (saturates, aromatics and resins) as hexane soluble fraction and 21 wt% of asphaltene (hexane-insoluble and toluenesoluble fraction) [56,57]. More detail of experiments can be found in Hosseinpour et al. [44,45]. All solvents including toluene (99%), n-hexane (99.6%) and chloroform (99%) were purchased from Merck Chemical Company. The chemicals were used as received. Freshly deionized water, prepared inhouse, was used throughout the experiments. The experiments were carried out in a batch stainless-steel autoclave reactor, constructed of 316 L stainless steel with a capacity of 10 ml (diameter and length of batch reactor are 7.5 mm and 230 mm, respectively). Heating was provided by an electric furnace by which the reactor heating up to the setpoint for 5 min. The reaction took place in the optimized condition, range of temperature is 350e500  C and also pressure is about 25e45 MPa. Argon was used to purge the reactor before it was

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sealed. After 60 min which is suitable time for desired reaction [45,46,56,57] the reactor was removed from the heater and immersed in an ice-water bath for about 30 min to stop the reaction. After cooling to ambient temperature, the reactor was opened and chloroform was added to recover the oil fractions. After evaporating the chloroform solvent, the amount of product was determined gravimetrically via solvent extraction method. First, the maltene fraction was separated by hexane followed by extraction the asphaltene with toluene, which solid coke remained insoluble at the end.

Simulation description Appropriate equation of state (EoS) As mentioned before, converting the lighter compound of heavy oil by in-situ production of hydrogen via partial oxidation and also excess hydrogen via WGSR reaction, was simulated by Aspen Plus®. In simulation, selecting a proper method for estimating the properties is the most important step which influence on the results of the simulation. In this regard, different EoS have been considered in the condition of high temperature and pressure and including incompatible polar-nonpolar compounds. Eventually, appropriate EoS is selected for predicting the properties of compounds in the studied system. A range of EoS related to high temperature and pressure conditions are listed in Table 1 which are recommended by Aspen with the capability for predicting the properties such as binary interaction parameters in severe conditions [58]. Among them, the reliability of Lee-Kessler EoS was verified for light gas compounds in HCW condition where € € cker (LK-PLOCK). the binary coefficients are modified with plo € LK-PLOCK EoS has been considered and applied for a wide range of temperatures and pressures in the recent experimental study of Hosseinpour et al. [57] which is an appropriate thermodynamic method for prediction the binary and activity € coefficients. LK-PLOCK is suitable for phase equilibrium with HCW that can describe behavior of each compound of system and consistent in a critical region [58,59].

Selection of model compound as a source of in-situ hydrogen According to the elemental analysis of maltene fraction in the feed (C ¼ 82.06 wt% and H ¼ 9.19 wt%), molar ratio of H/C was calculated 1.72:1. So general molecular formula of VR is provided as CnH1.72n. Coupling molecular weight of light compounds extracted from GC-MS analysis of maltene (see Fig. 1)

Fig. 1 e Distribution of light compounds in maltene fraction of feed with the capability of solubility in HCW as the source of active hydrogen (analyzed via GC-MS).

that is about 94.24 g/mol, and elemental analysis, chemical formula of representative compound was estimated C7H14 (n~7). Due to the complete solubility of maltene light hydrocarbons in HCW, representative compound has been considered as a source for producing the in-situ hydrogen in heavy oil via partial oxidation during upgrading of heavy oil in HCW.

Main chemical reactions Based on experimental data, the portion of light compounds in heavy oil is about 0.5% which in this study represented as cycloheptane. Reforming of these compounds for producing the in-situ hydrogen and therefore upgrading of heavy oil is very important. In this regards, the reforming reaction of light compounds of heavy oil is desirable reaction for upgrading the oil by partial oxidation. These reactions are very complex but the major reaction of this process has been widely described in the literature [1,24]. The major reactions are partial oxidation, steam reforming, WGSR and methanation which are represented as follows. Two major reactions for production of hydrogen are partial oxidation reforming (Eq. (1)) and WGSR (Eq. (2)). Side reactions such as methanation can have an effect on in-situ hydrogen product and limit the hydrogen production. However, the combination of steam reforming and partial oxidation as an autothermal reaction can be enhanced the hydrogen yield and decrease the undesired compounds

Table 1 e List of equation of states (EoS) recommended by Aspen Plus for severe condition [57]. Property method LK-PLOCK PSRK BWRS BWR-LS PR-BM PR-MHV2 RK-ASPEN RKS-BM RKS-WS SRK SRK-KD

Eos

Type

Appropriate for critical regions

€ cker Lee-Kessler-Plo Soave-Redlich-Kwong Benedict-Webb-Rubin-Starling Benedict-Webb-Rubin-Lee-Starling Peng-Robinson Peng-Robinson Redlich-Kwong-Aspen Redlich-Kwong-Soave-Boston-Mathias Redlich-Kwong- Soave Soave-Redlich-Kwong Soave-Redlich-Kwong

Virial Cubic Virial, Regression Virial Cubic Cubic Cubic Cubic, BM alpha Function Cubic Cubic Cubic

Yes Yes Yes Not Applicable Yes Yes Yes Yes Yes Yes Yes

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including methane and carbon monoxide. The influence of side reactions has been discussed later by considering the various parameters such as oxygen to heavy oil ratio. Cycloheptane partial oxidation:

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sections. Carbon formation for all simulations is inhibited thermodynamically which is related to relatively high portion of water.

Process simulation DHo (25  C) ¼ 2300 kJ/mol

C7H14þ7O247COþ7H2O

(1)

Water-gas shift reaction (WGSR): COþH2O4CO2þH2

DHo (25  C) ¼ 41 kJ/mol

(2)

Cycloheptane steam reforming: DHo (25  C) ¼ 1000 kJ/mol

C7H14þ7H2O47COþ14H2

(3)

Methane steam reforming: DHo (25  C) ¼ 210 kJ/mol

CH4þH2O4 3H2þCO

(4)

Methane dry reforming: DHo (25  C) ¼ 250 kJ/mol

CH4þCO24 2H2þ2CO

(5)

Hydrogen peroxide decomposition: H2O24 0.5O2þH2O

DHo (25 oC) ¼ 110 kJ/mol

(6)

Methanation reaction: COþ3H24 CH4þH2O CO2þ4H24 CH4þ2H2O

DHo (25  C) ¼ 210 kJ/mol DHo (25  C) ¼ 160 kJ/mol

(7) (8)

Equilibrium calculations By applying the minimization of Gibbs free energy, the equilibrium analysis of partial oxidation of heavy oil in HCW was undertaken. The desired conditions are considered (400  C & 25 MPa) for an estimate of the maximum theoretical yields of hydrogen and other species including CO, CO2, and methane (CH4) which this operating condition results from experimental works [4,25,30]. Equilibrium reaction for WGSR has been considered after the Gibbs reactor for maximizing the production of hydrogen. The results will be illustrated in next

In this study, the main idea is developing a model by appropriate EoS that will help to optimize the process. This target was achieved by sensitivity analysis of the model. Gibbs free energy minimization was applied to predict the equilibrium composition of each species in case of upgrading the heavy oil by oxidation process in HCW condition. The operating temperature and pressure are 400  C and 25 MPa, respectively which is related to HCW condition. This operating condition concluded from experiment works and illustrated before in experimental section. Therefore, R-Gibbs reactor calculates the composition of product and also heat of overall reaction regarding minimizing the Gibbs free energy. This type of reactor does not require a reaction set to be attached in order to function, so, initial estimation of the equilibrium and also kinetic rates of reaction are not required for this method. Conversion of the cycloheptane by oxidation process in presence of HCW by using the R-Gibbs reactor leads to carbon monoxide formation. This undesired component can be converted to active hydrogen molecules via WGS reaction to enhance the light portion of the heavy oil. So, by considering the R-EQUIL reactor, WGRS has occurred and more hydrogen will be produced by consumption of carbon monoxide and water. In R-EQUIL reactor, stoichiometric thermodynamic model is applied to estimate equilibrium composition of WGSR with reaction temperature and also equilibrium constant parameters. WGSR is moderate exothermic reaction, and thermodynamically unfavorable at elevated temperatures. So, WGSR reaction should be kept in temperatures about 60  C for maximizing the efficiency. So all simulations were done at mentioned operating temperature. The main purpose of using the equilibrium reactor is improving the efficiency of system by generating more hydrogen which is attributed to better upgrading the heavy oil to lighter compounds. The flowsheet of the upgrading process in Aspen Plus® is illustrated in Fig. 2. As shown in this figure, cycloheptane as representive of the light fraction of heavy oil, with acceptable miscibility in HCW, mixed with water and mixture is sent to high pressure pump which increases the pressure of system to

Fig. 2 e Process flow-sheet for hydrogen production in HCW including in-situ (R-GIBBS reactor) and excess hydrogen production (R-EQUIL reactor) from light compounds of heavy oil simulated by Aspen Plus software.

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25 MPa. Then temperature of system will be reached to 400  C by using a heater. Regarding oxidation of system, at first oxygen compressed to 25 MPa and then heated to 400  C. Therefore reactant including the cycloheptane, water, and oxygen sent to the R-Gibbs reactor as a feed. Oxidation of hydrocarbon in HCW occurs in R-Gibbs reactor which is the endothermic reaction and therefore, required heat is provided by heaters at temperature of 400  C. Hydrogen, carbon monoxide, carbon dioxide as well as methane are the products from Gibbs reactor. In this simulation, coke formation has not been considered in upgrading reaction. Product compounds enter to expander for reducing the pressure to atmospheric pressures and then cooled by exchanger to 60  C which is suitable for WGSR that converting the carbon monoxide to hydrogen and also carbon dioxide by water. WGSR is considered in an equilibrium reactor for increasing the hydrogen compound in the syngas and reducing the carbon monoxide. By increasing the portion of hydrogen in mixture of hydrocarbon, efficiency of upgrading process will be increased which is suitable for producing the valuable light hydrocarbon compounds in product stream and suppress the coke formation. At final, a flash drum has been considered for removing the liquids from gas phase. The list of applied equipments which are applied in simulations are brought in Table 2.

Results and discussion Sensitivity analysis on the type of feed As mentioned before, a representative of hydrocarbon has been introduced as cycloheptane. Fig. 3 indicates the various types of considered feed for representing the hydrocarbon compound. According to results of simulations and experimental works which is reported in ref. [4], the major portion of heavy oil as vacuum residue is maltene content and based on compounds of maltene, cycloheptane has been selected and applied for simulations. From the simulation results, it could be concluded that from thermodynamic point of view, there is

no significant variation in the product distribution (CH4, H2) from aliphatic to naphthenic (cyclic), however; the yield of methane are decreased by changing the composition of feed to aromatic compounds, e.g. benzaldehyde or benzoquinone. More branches of aliphatics (di-methylpentane) also lead to the more hydrogen and methane yield, oppose to di-methyl cyclopentane with lower hydrogen and methane yield.

Sensitivity analysis on temperature, pressure (density), water/feed, and O2/feed The existence of the catalyst is not considered in simulations, since almost all catalysts are unstable in HCW. Rapid deactivation of the catalyst due to poisoning from heteroatoms (sulfur, nitrogen, and traces of metals) present in low qualified heavy oil also is challenging. In this regard, temperature at high levels compensates the absence of catalyst. The temperature range up to 1200  C was used in sensitivity analysis of the system. Regarding equilibrium reactions in Gibbs reactor, converting reaction of cycloheptane for producing the hydrogen is endothermic and required energy, which was provided by heating up the feeds before entering to reactor. Besides the main partial oxidation reaction, the formation of methane from Eq. (7) and Eq. (8) reactions could be possible as side reactions. Therefore, in moderate temperature conditions, exothermic reaction including methane formation is prevailing and has a higher rate than partial oxidation of heavy oil, i.e., Eq. (1). In this condition formation of undesirable compound namely methane will be increased and hydrogen production decreased. Different parameters including ratio of oxygen to heavy oil, ratio of water to heavy oil, operating pressure have been considered in temperature range of 100e1200  C for studying the effect of these parameters on reactions of Gibbs reactor in adiabatic condition. Ratios of water to heavy oil are 99, 50, 25, 12, 9 and 6 and various ratio of oxygen to heavy oil has been considered. According to experimental results, temperature of 400  C and pressure of 25 MPa were considered as operating conditions of Gibbs reactor in HCW condition. Results of simulation and

Table 2 e List of equipment for simulating the upgrading process. Equipment

Tag name

Operating condition 

Temp. ( C) MIXER DRIVERS PUMP COMPRESSOR (ISENTROPIC MODEL) EXPANDER (ISENTROPIC MODEL) HEAT EXCHANGER HEAT EXCHANGER HEAT EXCHANGER HEAT EXCHANGER HEAT EXCHANGER REACTORS GIBBS REACTOR EQUILIBRIUM REACTOR COLUMNS FLASH DRUM

Comments

Pres. (bar)

MIX

30

1

-

PUMP COMP EXP

30 (Inlet) 30 (Inlet) 400 (Inlet)

250.5 250.5 1.4

Different discharge pressures have been applied Different discharge pressures have been applied Isentropic model with efficiency of 80%

HEAT1 HEAT2 HEAT3 COOL1

400 400 200 60

250 250 1.2 1.0

Pressure Pressure Pressure Pressure

R-GIBBS R-EQUIL

400 200

250 1.2

Minimizing the Gibbs free energy for oxidation reaction WGSR is applied for reactor

SEP

60

1.0

Gas e liquid separation

drop drop drop drop

is is is is

0.5 bar 0.5 bar 0.2 bar 0.2 bar

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Fig. 3 e Analysis of feed for selecting the appropriate compound. sensitivity analysis of system are considered and discussed in next sections.

Oxygen to heavy oil ratio The effect of the different molar ratio of oxygen to cycloheptane is indicated in Fig. 4 at the temperature range from 500 to 1200  C. In this regard, partial oxidation and reforming processes in various ratios of water to heavy oil have been considered at pressure of 25 MPa and consequently, required molar ratio of oxygen to heavy oil resulted from simulations. External heat was not considered for Gibbs reactor and therefore by adjusting the ratio of oxygen to heavy oil,

required heat for reforming was provided and auto-thermal reforming was carried out in adiabatic condition. Introduced reactions in Eq. (1) to (5) and (7) and (8) were occurred in reactor and main products of reactions were included as hydrogen, methane, carbon monoxide, carbon dioxide, and water. Oxygen and cycloheptane at outlet of reactor were negligible and converted to products by reforming and partial oxidation reactions. Regarding the trend of curves in Fig. 4, it is observed that by increasing the temperature of reactor, ratio of oxygen to hydrocarbon will be increased for providing the heat of reforming reaction by oxidation reaction of fuel. For water to heavy oil molar ratio of 99, higher ratio of oxygen to heavy oil was required than lower ratio of water to heavy oil. It is concluded that when water to heavy oil is increased at the same reforming temperature, higher ratio of oxygen to heavy oil will be required for providing the condition of auto-thermal reforming. Furthermore, in lower temperatures, oxygen in inlet of reactor is zero which contributes to the reforming reaction that does not need to heat via partial oxidation reaction. In this condition, required heat for reforming is provided by exothermic methanation reactions which are introduced in Eqs. (7) and (8).

Water to heavy oil ratio

Fig. 4 e Effect of oxygen to light hydrocarbon (HC) ratio for autothermal reforming at different temperature (P ¼ 25 MPa).

Different molar ratio of water to heavy oil (6, 12, 25, 50 and 99) has been considered for the simulated system in temperature range of 100e1200  C and pressure of 25 MPa. Results of simulation at the outlet of Gibbs reactor and also the equilibrium reactor which is related to WGSR are depicted in Figs. 5e8. Regarding Fig. 5, mole fraction of methane and carbon monoxide at outlet of Gibbs reactor is shown. It is observed that by increasing the temperature of system, mole fraction of methane will be decreased (see Fig. 5a) and in higher molar ratio of water to heavy oil, production of methane will be decreased. In Fig. 5b, increasing the temperature of system lead to formation the higher amount of carbon monoxide and when the ratio of water to heavy oil is increased, the

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Fig. 6 e H2 mole fraction (%) of (a) stream 04 and (b) PR at different conditions in dry basis (P ¼ 25 MPa). Fig. 5 e Mole fraction of methane and carbon monoxide at outlet of Gibbs reactor (P ¼ 25 MPa). formation of carbon monoxide will be decreased. The reason of decreasing trend of mole fraction of methane by increasing the temperature is methane steam reforming (Eq. (4)) which this reaction is endothermic and in higher level of temperature, rate of methane reforming will be increased and therefore the methane is consumed. Carbon monoxide is the product of methane steam reforming which by increasing the rate of this reaction, amount of carbon monoxide will be increased which a portion of this substance is consumed via reaction (2). So, it is concluded that the amount of methane and carbon monoxide at specified temperature are higher when lower water to heavy oil mole ratio is used.

Fig. 6 indicates the hydrogen mole fraction at the outlet of Gibbs reactor (Fig. 6a) and also equilibrium reactor (Fig. 6b) at different molar ratio of water to heavy oil. It is concluded that mole fraction of hydrogen for all molar ratio of water to HO will be increased up to maximum value by increasing the temperature of system. In higher molar ratio, curves after maximum value are approximately constant (900e1200  C) while in lower ratios, curves are increased continuously. It can be observed from these curves that reaching to maximum value of hydrogen mole fraction at higher molar ratio was occurred in lower temperatures rather than lower molar ratio. In maximum value, due to reforming reaction and also water gas shift reaction (Eq. (2) and (4)), amount of methane and carbon monoxide are negligible for higher ratio of water to heavy oil which is related to existence of excess water in

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Fig. 7 e H2 molar flow rate at outlet of equilibrium reactor (P ¼ 25 MPa).

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a portion of hydrogen will be consumed and react with carbon monoxide and also carbon dioxide to produce methane substance. The role of temperature is essential which by increasing the temperature, reforming reaction (Eq. (4)) shift to right side and produced more hydrogen against the methanation reaction that is exothermic reaction and shift to left side of Eqs. (7) and (8) and therefore, lead to consumption of methane and produced the hydrogen. Therefore, by increasing the temperature, the hydrogen molar flow rate will be increased that is shown in Fig. 7. Fig. 8 indicates the yield of hydrogen product at outlet of Gibbs reactor at different molar ratios of water to heavy oil. It is obvious that by increasing the molar ratio, yield of hydrogen will be increased and achieving to maximum value in higher molar ratio of water to HO. The hydrogen yield for molar ratio of 99 is about 87% at maximum value which is related to temperature of 900  C. Conversion of heavy oil as cycloheptane is approximately 100% via partial oxidation and also reforming reactions which these reactions lead to producing the hydrogen substance. As shown in Fig. 8, by decreasing the molar ratio of water to heavy oil, maximum value of yield will be decreased and achieved in higher temperature than the higher molar ratio.

Effect of pressure (water density) The effect of pressure on hydrogen mole fraction at the outlet of the Gibbs reactor is shown in Fig. 9. In this regard, by increasing the temperature, reforming reaction will be occurred at higher rate of reaction and therefore portion of hydrogen substance at outlet of reactor was increased. Meanwhile, by increasing the pressure of system, regarding Le Chatelier's principle, the reaction shifts to a side of reaction with lower molecules and therefore by considering the reforming reaction, production of hydrogen substance will be

Fig. 8 e H2 yield at outlet of Gibbs reactor in different ratio of water to HC (P ¼ 25 MPa).

system and lead to consume of methane and carbon monoxide as illustrated before and indicated in Fig. 5. The molar flow rate of hydrogen at different molar ratios of water to heavy oil is indicated in Fig. 7. It is observed that by increasing the molar ratio of water to heavy oil, the molar flow rate of hydrogen at outlet of equilibrium reactor was decreased but regarding increasing the temperature, the molar flowrate of hydrogen was increased. Decreasing the hydrogen product at higher molar ratio of water to heavy oil related to methanation reactions which are indicated in Eqs. (7) and (8). For the higher amount of water, the reforming reaction will be occurred for producing the hydrogen but regarding methanation reactions,

Fig. 9 e Effect of pressure on hydrogen product of Gibbs reactor in different temperature of system.

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decreased. This trend is indicated in Fig. 9 which by increasing the pressure, hydrogen mole fraction was decreased.

Experimental results of heavy oil upgrading in HCW The effect of above-mentioned parameters, i.e., temperature, pressure (density) and the amount of oxygen and water were also studied experimentally during the upgrading heavy oil (VR) in HCW. The experiment design is illustrated in Table 3. Since the upgrading performed in batch system, water density has been defined as amount of water based on gram to volume of reactor (10 ml). Identical proportions of two substances, water, and heavy oil, were applied in all experiments. By applying the hydrogen peroxide as source of oxygen, for partial oxidation and reforming the heavy oil, different ratio of O2 to feed considered as 0, 0.25 and 0.5. In this regard, treatment experiments of VR in HCW in the presence of hydrogen peroxide were carried out in batch reactor and the results are reported in Figs. 10e12. Through the solvent extraction method, weight percentage of upgraded oil includes maltene (saturated, aromatics, and resins) with the ability to be dissolved in hexane; asphaltene (soluble in toluene) and solid coke (non-soluble) in treated VR have been considered and represented.

Fig. 10 e Effect of temperature on upgrading the heavy oil in HCW (operational condition: P ¼ 27 MPa, H2O2/heavy oil ¼ 0.25 (v/v), and H2O2/H2O ¼ 0.5 (v/v)).

Effect of temperature According to experimental results, by increasing the upgrading temperature, the color of upgraded products become brighter (see Fig. 10) indicating the higher fraction of light product. This effect was predicted by applied simulation which asserts the greater quantity of hydrogen at the higher temperatures. However, more fraction of solid residue was obtained. The contradictory effect of temperature could be seen from numerous aspects: temperature has positive effect on cracking system via provides activation energy of cracking, particularly cracking of heavier fractions (asphaltene). Further by increasing temperature, the better miscibility of oil in HCW could be deduced due to the modification in Hansen solubility parameter (HSP) of heavy oil-HCW system which leads to more solvation and dispersion of heavy oil in HCW, hence; lower degree of coke formation [12,41,59e61]. On the other hand, condensation of polycyclic aromatics, which are the precursor of coke, accelerates at higher temperatures.

Consequently, the optimum temperature for upgrading should be chosen, both from the quality and quantity point of view which are selected at Temperature of 450  C. At this temperature, the amount of coke is comparatively low as well as degree of asphaltene.

Effect of pressure (water density) In Fig. 11 (a,b), the effect of pressure on upgrading the heavy oil has been considered through the changing the amount of water, but other parameters (O2/heavy oil and water/heavy oil) remained fixed. Considering in the pressure of system which is reported in Table 3, it is concluded that by increasing the pressure from 27 MPa to 45 MPa, coke formation was tremendously increased particularly at higher temperatures due to the change in phase behavior of oil and water mixture. It is indicated from results of simulations that by increasing the pressure, hydrogen production was decreased and

Table 3 e Parameters studied in experimental works. No. 1 2 3 4 5 6 7 8 9 10 11 12 13

Effect of parameters

T (oC)

H2O2 (ml)

Water density (g.ml-1)

Pressure (MPa)

Temperature @ constant density

350 400 450 500 400 450 500 400 450 500 450 450 450

1 1 1 1 1 1 1 1 1 1 0 0.25 0.5

0.2 0.2 0.2 0.2 0.2 0.15 0.1 0.555 0.35 0.2 0.2 0.2 0.2

17 27 35 45 27 27 27 45 45 45 35 35 35

@ P1 ¼ 27 MPa

@ P2 ¼ 45 MPa

H2O2/water

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Fig. 12 e Effect of hydrogen peroxide on upgrading of heavy oil compounds (operational condition: T ¼ 450  C, P ¼ 27 MPa).

Effect of oxygen (H2O2)

Fig. 11 e Effect of pressure on behavior of system for upgrading the heavy oil compounds (operational condition: H2O2/heavy oil ¼ 0.25 (v/v), and H2O2/H2O ¼ 0.5 (v/v)).

therefore upgrading process tends to formation of coke rather than converting to valuable lighter compounds. Like to the temperature, pressure (water density) influence on upgrading system in opposite ways: according to the previous studies [12,41,59,60], pressure has significant effect on condensation and fusion of polycyclic aromatics and coke formation. On the other hand, pressure has positive influence on HSP; hence better miscibility of oil in HCW which leads to the lower formation of coke. From kinetic point of view, pressure influence positively on WGS reaction and consequently degree of active hydrogen from water. All means that controlling the operating conditions of system including temperature and pressure, miscibility of mixture of oil and water will be improved and therefore conversion of heavy compounds to lighter such as maltene occurred more than coke making process.

Considering the ratio of hydrogen peroxide to water, different ratios have been considered and reported in Fig. 12. In these cases, it is concluded that by increasing the amount of H2O2 in water, asphaltene and coke formation will be decreased, most probably due to the influence of active hydrogen on conversion of heavy constitutes to lighter fractions, rather than the formation of coke. In other hands, tendency of system to formation the lighter compounds is more than coke formation. This behavior is contributed to the formation of active hydrogen during treatment of heavy oil [12,25,61e63] and biooil [31]. In this condition, H2O2 decomposes to oxygen and water molecules (see Eq. (6)) and products of this conversion contribute to partial oxidation and WGS reactions which are related to increasing the active hydrogen products for better upgrading the heavy oil compounds. In simulation section, effect of water and oxygen on production of hydrogen substances has been considered and results analyzed. Although higher amount of O2 seems the modification on conversion of heavy oil to maltene and lighter compounds, however, it should be careful that the active hydrogen comes from partial combustion of oil in HCW. In other words, an optimum ratio of O2/oil should be selected with low degree of loss of hydrocarbon. It should be noted that this work has been investigated the system from standpoint of thermodynamics and recommends the optimized condition in which maximum production of hydrogen will occur for better upgrading, while experiment work focuses on kinetic consideration of upgrading the heavy oil. In kinetic considerations, temperature constraints should be taken into account for minimizing the formation of coke in products and therefore maximizing the contribution of lighter hydrocarbons including maltene compounds which this operating condition can be concluded by applying the results of this work.

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Finally, it is worthy to mention that temperature and pressure have other physicochemical effects on HCW, which has not been considered in the simulation due to the complexity of the upgrading system. Against to the thermal cracking in dry condition with significant amount of coke, the phase behavior of heavy oil (light and heavy part) in HCW could be modified where more solubility of heavy oil in HCW is expected at higher temperature with less coke. In other words, by increasing the solubility of heavy oil in HCW, the cracking system shifted from oil to the HCW system which leads to lower amount of coke. Increasing the pressure also has the same effect as temperature on improving the solvation and dispersion of heavy oil HCW in the same way. On the other hand, condensation of polycyclic aromatics, as source of making coke, which is substantial in heavy oil, accelerates by increasing both temperature and pressure [63]. This contradictory effect of parameters makes the upgrading system more complex, but the important note is that higher degrees of active hydrogen available in HCW suppress the formation of coke via effective hydrogenation of heavy constituents. This is the beauty of thermodynamic simulation implementation which can provide noteworthy information about upgrading system.

Conclusion Regarding experimental results, simulations were applied to determine the main parameters for the maximizing of the insitu hydrogen product and subsequent improvements to the € heavy oil upgrading process. LK- PLOCK method was used for simulations in supercritical conditions. Partial oxidation and reforming processes as main reactions were considered for simulation the producing the hydrogen from cycloheptane as representative of light compounds of heavy oil. Side reactions leading to production of the by-products are also considered in simulations. In this regard, in-situ produced hydrogen was used for upgrading the heavy oil to valuable lighter compounds. According to simulations, it is concluded that produced gases from upgrading can be separated and by applying the WGSR process, more hydrogen will be produced and returned to upgrading reactor for improving the performance of upgrading process. Also, simulations indicated that by increasing the amount of O2/heavy oil as well as temperature, heavy oil upgrading improves toward lighter fraction (maltene) with less coke. In other words, increasing the molar ratio of oxygen to heavy oil and molar ratio of water to heavy oil at optimum operating conditions leads to producing more hydrogen and consequently, better upgrading of heavy oil and hydrotreating process. Regarding the simulation, noncatalytic treating of heavy oil (vacuum residue) is performed in mixture of hydrogen peroxide and HCW in order to verify the simulation results. It is concluded that, increasing the amount of hydrogen peroxide in HCW leads to better upgrading of heavy oil regarding the producing more hydrogen from light oil reforming and WGS reactions. Also, the effect of temperature and pressure on upgrading is investigated and results at the optimum condition are as T ¼ 450  C, P ¼ 27 MPa, H2O2/heavy oil ¼ 0.25 (v/v), and H2O2/ H2O ¼ 0.5 (v/v).

references

[1] Castaneda LC, Munoz JAD, Ancheyta J. Current situation of emerging technologies for upgrading of heavy oils. Catal Today 2014;220e222:248e73. [2] Canıaz RO, Erkey C. Process intensification for heavy oil upgrading using supercritical water. Chem Eng Res Des 2014;92:1845e63. [3] Marafi A, Albazzaz H, Rana MS. Hydroprocessing of heavy residual oil: opportunities and challenges, catal. Today 2019;329:125e34. [4] Hosseinpour M, Ahmadi SJ, Fatemi S. Successive cooperation of supercritical water and silica-supported iron oxide nanoparticles in upgrading of heavy petroleum residue: suppression of coke deposition over catalyst. J Supercrit Fluids 2015;100:70e8. [5] Zhang Y, Yu D, Li W, Wang Y, Gao S, Xu G. Fundamentals of petroleum residue cracking gasification for coproduction of oil and syngas. Ind Eng Chem Res 2012;51:15032e40. [6] Ng S, Zhu Y, Humphries A, Nakajima N, Tsai T, Ding F, Ling H, Yui S. Key observations from a comprehensive FCC study on Canadian heavy gas oils from various origins: 1. Yield profiles in batch reactors. Fuel Process Technol 2006;87:475e85. [7] Speight J. New approaches to hydroprocessing. Catal Today 2004;98:55e60. [8] Ng F, Tsakiri S. Activation of water in emulsion for catalytic desulphurization of benzothiophene. Fuel 1992;71:1309e14. [9] Li J, Wang X, Tang X, Zhang M, Zheng X, Wang C, Tang Z. Upgrading of heavy oil by thermal treatment in the presence of alkali treated Fe/ZSM-5, glycerol, and biomass. Fuel Process Technol 2019;188:137e45. [10] Elahi SM, Khoshooei MA, Scott CE, Chen Z, Pereira-Almao P. In-situ upgrading of heavy oil using nano-catalysts: a computational fluid dynamic study of hydrogen and vacuum residue injection. Can J Chem Eng 2018;219(97):1352e60.  andez P, Portales-Martı´nez B, Laredo GC, [11] Schacht-Hern rezRomo P, Domı´nguez-Esquivel JM. Homogeneous Pe catalyst for in-situ hydrotreating of heavy oils. Appl Catal, A 2019;577:99e106. [12] Hosseinpour M, Fatemi S, Ahmadi SJ, Morimoto M, Akizuki M, Oshima Y, Fumoto E. Synergistic effect of supercritical water and iron oxide nanoparticles in in-situ catalytic upgrading heavy oil with formic acid. Isotopic study. Appl Catal B: Environ 2018;230:91e101. [13] Huang J, Zhu C, Lian X, Feng H, Sun J, Wang L, Jin H. Catalytic supercritical water gasification of glucose with in-situ generated nickel nanoparticles for hydrogen production. Int J Hydrogen Energy 2019;44:21020e9. [14] Byrd AJ, Kumar S, Kong L, Ramsurn H, Gupta RB. Hydrogen production from catalytic gasification of switchgrass biocrude in supercritical water. Int J Hydrogen Energy 2011;36:3426e33. [15] Elif D, Nezihe A. Hydrogen production by supercritical water gasification of fruit pulp in the presence of Ru/C. Int J Hydrogen Energy 2016;41:8073e83. [16] Fan YJ, Zhu W, Gong M, Su Y, Wang CY. Investigation of the interaction between intermediates from gasification of biomass in supercritical water: formaldehyde/formic acid mixtures. Int J Hydrogen Energy 2018;43:13090e7. [17] Avbenake OP, Al-Hajri RS, Jibril BY. Catalytic upgrading of heavy oil using NiCo/g-Al2O3 catalyst: effect of initial atmosphere and water-gas shift reaction. Fuel 2019;235:736e43. [18] Leal AL, Soria MA, Madeira LM. Autothermal reforming of impure glycerol for H2 production: thermodynamic study

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 4 ( 2 0 1 9 ) 2 7 6 7 1 e2 7 6 8 4

[19]

[20]

[21]

[22]

[23]

[24]

[25]

[26] [27]

[28]

[29]

[30]

[31]

[32]

[33]

[34]

[35]

including in situ CO2 and/or H2 separation. Int J Hydrogen Energy 2016;41:2607e20. Pairojpiriyakul T, Croiset E, Kiatkittipong K, Kiatkittipong W, Arpornwichanop A, Assabumrungrat S. Catalytic reforming of glycerol in supercritical water with nickel-based catalysts. Int J Hydrogen Energy 2014;37:14739e50. Patcharavorachot Y, Chatrattanawet N, Arpornwichanop A, Assabumrungrat S. Optimization of hydrogen production from three reforming approaches of glycerol via using supercritical water with in situ CO2 separation. Int J Hydrogen Energy 2019;44:2128e40. Patcharavorachot Y, Saebea D, Suthida Authayanun, Arpornwichanop A. Hydrogen and power generation from supercritical water reforming of glycerol and pressurized SOFC integrated system: use of different CO2 adsorption process. Int J Hydrogen Energy 2018;43:17821e34. Penningera JML, Maassa GJJ, Marco Rep. Compressed hydrogen-rich fuel gas (CHFG) from wet biomass by reforming in supercriticalwater. Int J Hydrogen Energy 2007;32:1472e6. Zhang R, Jiang W, Cheng L, Sun B, Sun D, Bi J. Hydrogen production from lignite via supercritical water in flow-type reactor. Int J Hydrogen Energy 2010;35:11810e5. Sato T. Upgrading of heavy oil by hydrogenetation through partial oxidation and water-gas shift reaction in supercritical water. J Jpn Pet Inst 2014;57:1e10. Hosseinpour M, Fatemi S, Ahmadi SJ. Deuterium tracing study of unsaturated aliphatics hydrogenation by supercritical water during upgrading of petroleum heavy oil. Part I: noncatalytic cracking. J Supercrit Fluids 2016;107:278e85. Akiya N, Savage P. Roles of water for chemical reactions in high temperature water. Chem Rev 2002;102:2725e50. Dong X, Gan Z, Lu X, Jin W, Yu Y, Zhang M. Study on catalytic and non-catalytic supercritical water oxidation of pnitrophenol wastewater. Chem Eng J 2015;277:30e9. Gong Y, Guo Y, Sheehan JD, Chen Z, Wang S. Oxidative degradation of landfill leachate by catalysis of CeMnOx/TiO2 in supercritical water: mechanism and kinetic study. Chem Eng J 2018;331:578e86. Chen Z, Wang G, Yin F, Chen H, Xu Y. A new system design for supercritical water oxidation. Chem Eng J 2015;269:343e51. Qian L, Wang S, Ren M, Wang S, Ren L, Cheng Y, Wang S, Meng X, Qin Q, Yang J. Oxidation behavior of the supercritical water on the ternary Ni-W-P coating. Chem Eng J 2019;370:1388e406. Hosseinpour M, Golzary A, Saber M, Yoshikawa K. Denitrogenation of biocrude oil from algal biomass in high temperature water and formic acid mixture over HþZSM-5 nanocatalyst. Fuel 2017;206:628e37. Md Isa K. Pyrolysis oil upgrading using supercritical water, with tetralin and 1-methylnaphtalene as a baseline study. Energy Convers Manag 2016;117:558e66.  n J, Arcelus-Arrillaga P, Garcı´a L, Arauzo J. Production Remo of gaseous and liquid bio-fuels from the upgrading of lignocellulosic bio-oil in sub- and supercritical water: effect of operating conditions on the process. Energy Convers Manag 2016;119:14e36. rrez Ortiz FJ. Fischer-Tropsch biofuels Campanario FJ, Gutie production from syngas obtained by supercritical water reforming of the bio-oil aqueous phase Energy. Convers Manage 2017;150(15):599e613. Al-Atta A, Huddle T, Garcı´a Y, FidelMato R, Marı´aJG S, Cocero J, Gomes R, Lester E. A techno-economic assessment of the potential for combining supercritical water oxidation with ‘in-situ’ hydrothermal synthesis of nanocatalysts using a counter current mixing reactor. Chem Eng J 2018;344:431e40.

27683

[36] Hosseinpour M, Amiri H, Ahmadi SJ, Mousavian MA. The role of supercritical water on the rapid formation of ZSM-5 nanocatalyst. J Supercrit Fluids 2016;107:479e85. [37] Hosseinpour M, Charkhi A, Ahmadi SJ. Nanocrystalline zeolites in supercritical water. Part A: opportunities and challenges for synthesis using organic templates. J Supercrit Fluids 2015;102:40e9. [38] Hosseinpour M, Ahmadi SJ, Charkhi A, Allahyari SA. A rapid production of pure TMA-montmorillonite nanoclay in supercritical water: study on powder crystallinity and adsorption capacity. J Supercrit Fluids 2014;95:236e42. [39] Dargahi M, Kazemian H, Soltanieh M, Hosseinpour M, Rohani S. High temperature synthesis of SAPO-34: applying an L9 Taguchi orthogonal design to investigate the effects of experimental parameters. Powder Technol 2012;217:223e30. [40] Dargahi M, Kazemian H, Soltanieh M, Rohani S, Hosseinpour M. Rapid high-temperature synthesis of SAPO34 nanoparticles. Particuology 2011;9:452e7. [41] Morimoto M, Sato S, Takanohashi T. Conditions of supercritical water for good miscibility with heavy oils. J Jpn Pet Inst 2010;53:61e2. [42] Timko MT, Ghoniem AF, Green WH. Upgrading and desulfurization of heavy oils by supercritical water. J Supercrit Fluids 2014;96:114e23. [43] Tan XC, Liu QK, Zhu DQ, Yuan PQ, Cheng ZM, Yuan WK. Pyrolysis of heavy oil in the presence of supercritical water: the reaction kinetics in different phases. Reaction Eng. Kin. Catal. 2014;61:857e66. [44] Hosseinpour M, Fatemi S, Ahmadi SJ. Catalytic cracking of petroleum vacuum residue in supercritical water media: impact of a-Fe2O3 in the form of free nanoparticles and silica-supported granules. Fuel 2015;159:538e49. [45] Hosseinpour M, Fatemi S, Ahmadi SJ. Deuterium tracing study of unsaturated aliphatics hydrogenation by supercritical water during upgrading of petroleum heavy oil. Part II: hydrogen donating capacity of water in the presence of iron (III) oxide nanocatalyst. J Supercrit Fluids 2016;110:75e82. [46] Sato T, Tomita T, Trung PH, Itoh N, Sato S, Takanohashi T. Upgrading of bitumen in the presence of hydrogen and carbon dioxide in supercritical water. Energy Fuel 2013;27:646e53. [47] Karbalaee Habib F, Diner C, Stryker J, Semagina N, Gray M. Suppression of addition reactions during thermal cracking using hydrogen and sulfided iron catalyst. Energy Fuels 2013;27:6637e45. [48] Sim S, Kim J, Bae KongW, Kang J, Y-Woo Lee. Kinetic study of extra heavy oil upgrading in supercritical methanol with and without zinc nitrate. J Supercrit Fluids 2019;146:144e51. [49] Savage P. Organic chemical reactions in supercritical water. Chem Rev 1999;99:603e21. [50] Sato T, Trung PH, Tomita T, Itoh N. Effect of water density and air pressure on partial oxidation of bitumen in supercritical water. Fuel 2012;95:347e51. [51] Sato T, Adschiri T, Arai K, Rempel GL, Ng FTT. Upgrading of asphalt with and without partial oxidation in supercritical water. Fuel 2003;282:1231e9. [52] Alshammari Y, Hellgardt K. Partial oxidation of nhexadecane through Partial oxidation of n-hexadecane through decomposition of hydrogen peroxide in supercritical water. Chem Eng Res Des 2015;93:565e75. [53] Alshammari Y, Hellgardt K. Sub and supercritical water reforming of n-hexadecane in a tubular flow reactor. J Supercrit Fluids 2016;107:723e32. [54] Alshammari YM, Hellgardt K. Thermodynamic analysis of hydrogen production via hydrothermal gasification of hexadecane. Int J Hydrogen Energy 2012;37:5656e64.

27684

i n t e r n a t i o n a l j o u r n a l o f h y d r o g e n e n e r g y 4 4 ( 2 0 1 9 ) 2 7 6 7 1 e2 7 6 8 4

[55] Wang S, Wang Q, Song X, Chen J. Dry autothermal reforming of glycerol with in situ hydrogen separation via thermodynamic evaluation. Int J Hydrogen Energy 2017;42:828e47. [56] Hosseinpour M, Fatemi S, Ahmadi SJ. Isotope tracing study on hydrogen donating capability of supercritical water assisted by formic acid to upgrade heavy oil: computer simulation vs. experiment. Fuel 2018;225:161e73. [57] Aspen Physical Property System. Physical property methods, version 8.3. Aspen Technology; 2013. [58] Plocker U, Knapp H, Prausnitz J. Calculation of high-pressure vapor-liquid equilibria from a corresponding-states correlation with emphasis on asymmetric mixtures. Ind Eng Chem Process Des Dev 1978:324e32. [59] Morimoto M, Sato S, Takanohashi T. Effect of water properties on the degradative extraction of asphaltene using supercritical water. J Supercrit Fluids 2012;68:113e6.

[60] Morimoto M, Sugimoto Y, Saotome Y, Sato S, Takanohashi T. Effect of supercritical water on upgrading reaction of oil sand bitumen. J Supercrit Fluids 2010;55:223e31. [61] Adschiri T, Shibata R, Sato T, Watanabe M, Arai K. Catalytic hydrodesulfurization of dibenzothiophene through partial oxidation and a water-gas shift reaction in supercritical water. Ind Eng Chem Res 1998;37:34e8. [62] Arai K, Adschiri T, Watanabe M. Hydrogenation of hydrocarbons through partial oxidation in supercritical water. Ind Eng Chem Res 2000:4697e701. [63] Hosseinpour M, Akizuki M, Oshima Y, Soltani M. Influence of formic acid and iron oxide nanoparticles on active hydrogenation of PAHs by hot compressed water. Isotope tracing study. Fuel 2019;254:115675.