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Aquathermolysis of heavy oil using nano oxides of metals
Author’s Accepted Manuscript AQUATHERMOLYSIS OF HEAVY OIL USING NANO OXIDES OF METALS Alfiya Lakhova, Sergey Petrov, Dina Ibragimova, Galina Kayukova, Aliya Safiulina, Alexey Shinkarev, Rachael Okekwe www.elsevier.com/locate/petrol
PII: DOI: Reference:
S0920-4105(17)30344-3 http://dx.doi.org/10.1016/j.petrol.2017.02.015 PETROL3879
To appear in: Journal of Petroleum Science and Engineering Received date: 25 July 2016 Revised date: 7 February 2017 Accepted date: 22 February 2017 Cite this article as: Alfiya Lakhova, Sergey Petrov, Dina Ibragimova, Galina Kayukova, Aliya Safiulina, Alexey Shinkarev and Rachael Okekwe, AQUATHERMOLYSIS OF HEAVY OIL USING NANO OXIDES OF M E T A L S , Journal of Petroleum Science and Engineering, http://dx.doi.org/10.1016/j.petrol.2017.02.015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
AQUATHERMOLYSIS OF HEAVY OIL USING NANO OXIDES OF METALS Alfiya Lakhova¹, Sergey Petrov¹,²,Dina Ibragimova ¹,², Galina Kayukova², ³, Aliya Safiulina¹, Alexey Shinkarev³,Rachael Okekwe ¹
¹Kazan National Research Technological University, 420015, Russia, Kazan, Karl Marx St., 68, ²Kazan Federal University, 420008, Russia, Kazan, Kremlevskaya str., 18, ³A.E. Arbuzov Institute of Organic and Physical Chemistry Kazan Scientific Center, Russian Academy of Sciences, 420088, Russia, Kazan, Arbuzov st., 8 E-mail: [email protected], [email protected], [email protected]
The effect of suspended nanoparticles of magnetite and hematite on thermal decomposition of heavy oil at a temperature of 360 ° C in a vapor medium at different system pressures is revealed. The preferential destruction reactions of macromolecular components of oil, which lead to the reduction of oil viscosity, are established. The effect of zinc and aluminum oxides as additives initiating cracking of hydrocarbon bonds is studied. The changes in structure of the component of the converted products, as compared to the original crude oil, are obtained. Conducting the process in the presence of additives at a pressure of 11 MPa led to the reduction of the aromaticity of the final products, increase in the yield of hydrocarbon oils and the formation of gaseous products. It is observed that the amount of asphalt-resinous substances is reduced as the result of their conversion in the presence of additives. Rheological curves of conversion products are obtained, based on them the peculiarities of viscosity-temperature characteristics change can be shown. Keywords: homogeneous catalysis, high-viscosity oil, Nano-sized particles, iron oxides, the component composition of oil, rheological curve.
1. Introduction In modern refineries, the proportion of heavy oil in total volume increases every year. It is reported by the International Energy Agency that the worldwide resources of heavy oil are around 6 trillion barrels, which are mainly located in Canada, Venezuela, Russia and the USA. A review on recent advances on non-catalytic and catalytic process technologies for upgrading of heavy oils and residues is given in the article [1]. Therefore, there is a crucial need for new upgrading technologies that would provide them with a cost-effective development based on an efficient process technology and enhancement of catalytic systems. Catalytic performance can be improved by the use of various transition 1
metal precursors, additives, preparation techniques, use of other non-conventional metals, new active phases (carbides, nitrides etc.) and promoters, modifying of supports[2]. As many authors have noted [2]– [4], the development of catalytic systems has undergone two main stages: heterogeneous solid phasestage and homogeneous dispersed phase-stage. The homogeneous dispersed catalysts are divided into water-soluble (Mo, Ni oxide with aqueous ammonia of Chevron Inc.; Mo, V and Fe metal oxide or salt and heteropoly acid of UOP Co.; Ni, Fe, Mo and Fe-Co liquid catalyst of Petro China Company Limited; Phosphomolybdic acid ammonium heptamolybdate molybdenum oxalate of Exxon Research and Engineering Co. etc.),and oil-soluble (Mo or W salts of fatty acids of Chevron Inc.;CrO3tert-butyl alcohol, Molybdenum alicyclic or naphthenate, Fe2O3 and Mo naphthenate of Exxon Research and Engineering Co.; Iron pentacarbonyl or molybdenum 2-ethylhexanoate of Alberta Oil Sands Technology and Research Authority etc.) [2]. One of the key and promising areas is in using nano-scale catalysts. They have significant advantages, namely large surface area in the absence of the porous structure, which could be plugged with coke, high stability of activity and the elimination of diffusion control in the heavy oil feedstock. In the article by Canadian scientists the catalytic activity of micro particles and nanoparticles of nickel in the thermolysis reactions of Athabasca oil is compared. The authors found a significant reduction in viscosity of the converted products with nano-sized particles, apparently due to greater catalytic surface area [5]. It was proposed that nano-nickel catalyst in the aquathermolysis of extra-heavy oil San56-13-19 accelerated the pyrolysis of asphaltene, which led to the production of O-containing substances and, therefore to the reduction of viscosity up to 90.36% [6]. Hydrocracking of heavy residue in the presence of dispersed colloidal catalyst (nanosheet-structured WS2) was compared with those of bulk WS2 and MoS2. The single-layer WS2 catalyst provided high yield of fuel (45.4 wt.%) and asphaltene conversion (75.3 wt.%) [7]. Most common active catalyst components are salts of various metals, such as chlorides, sulphates, nitrates of nickel, iron, cobalt [8], [9]. iron derivatives (sulfates, naphtenates, sulfonates etc.) as catalysts have comparatively low costs. It was reported that Tris (acetylacetonato) iron (III) forms magnetic nanoparticles during aquathermolysis of heavy oil and leads to deep conversion of resins into light components [10]. Most common precursors for catalysts are molybdates [11]–[13]. Metallic oxide nanoparticles [14], [15] are widely used as precursors. A MoO3-deep eutectic solvent (DES) catalyst precursor, used in aquathermolysis, provided the reduction of viscosity of heavy oil by 43 % [16]. At high temperatures the metallic salts decompose to oxides, which tend to form sulfides in the presence of hydrogen sulfide. Comparative experiments on the resins and asphaltenes conversion of Liaohe oil showed that the conversion degree is higher in the presence of oil-soluble catalyst precursor – naphthenates of Ni and Fe, rather than sulphates of these metals [17]. Similar observations were made in 2
the study of complex compounds of iron and Gemini surfactants [18]. During the heavy oil conversion process at 170 ° C for 24 hours in the presence of Fe2(SO4)3 [19], the decrease in viscosity amounted to 69%, whereas in the presence of iron naphthenate – up to 83%. The research aimed to produce efficient and inexpensive catalytic systems for upgrading of heavy hydrocarbon resources is of high priority nowadays. There is a crucial need for in-depth knowledge of the nature of the thermal catalytic conversion of heavy oils in relation to its composition and the presence of various nano-sized oxide particles in it. Therefore, optimum technologies, aimed at improving the efficiency of development of specific heavy crude oil deposits, can be successfully selected. The present work is devoted to identifying the changes in the hydrocarbon composition and rheological characteristics of the products of aquathermolysis of the biodegraded heavy crude oil, depending on its content of iron oxides nanoparticles, aluminum, zinc, as well as nickel carbonate at various temperature and pressure conditions.
2. Experimental Procedure 2.1. Raw materials (Objects) The object of the research is the biodegraded heavy crude oil from carbonate rock, found in Ashal’cha oil field in the Republic of Tatarstan. The density of the heavy crude oil under normal conditions is 0,9512 g/cm3. It is rich in resinous-asphaltene compounds (up to 45%) and sulphur (up to 4.8%), and has low content of light fractions boiling up to 350 ° C (up to 28%). N-alkanes are not present in it. Into the heavy crude oil, we added metal-containing substances, like hematite particles Fe2O3 (200nm), alumina γ-Al2O3 and ZnO, having a particle size up to 40 nm, stabilized with 4-methyl-2pentanone, and Nickel (II) carbonate, having a particle size up to 100 nm. The advantage of the finedispersed particles of metal oxides is their spatial accessibility to high-molecular compounds of heavy crude oil. Metal oxides were selected as components exhibiting catalytic activity, because they accelerate the breakdown of the С–S, С–С bonds, whilst hydrogenating metals enhance breakdown of С-О bonds of high-molecular components of the heavy crude oil. For instance, nickel carbonate accelerates the destructive hydrogenation reaction. Upon reaction with steam, metal oxides are reduced with the formation of magnetite and hydrogen according to the following mechanism: 3Fe + 4H2O = Fe3O4 + 4H2; hydrogen produced can participate in the hydrogenation reactions [20] 2.2. Aquathermolysis experiments The introduction of catalyst systems into bituminous oil is carried out through an aqueous phase. The aqueous suspension containing nano-sized particles was prepared by mechanical activation in 3
ultrasonic plant Il100-6/1-22/44 at a frequency of 22 kHz ultrasonic waves, and energy density of 5 W/cm². The plant capacity varies from 630 W up to 5 kW, at an operating frequency of 22 ± 10% кНz. Research on the thermal catalytic refining of oil was carried out in a laboratory batch reactor under isothermal conditions at high temperatures and pressures, the experiments lasted up to 3.5 hours. The plant is equipped with a heated autoclave of 2 liters with a motorized stirrer, a reservoir for collecting final products and a steam mixture supply module, which can measure and control mass flow (Fig. 1). The reaction mixture (crude oil, water, metal-containing compounds) with a total volume of 1 liter was loaded into the autoclave. The initial pressure corresponded to the atmospheric pressure, when the reaction mixture was heated up to 380°C, pressure increased up to 21 MPa. After the experiment, the reactor was allowed to cool naturally to room temperature to reduce the resulting overpressure.
2.3. Analysis of products The resulting product contained water, which was removed by standard method of «Bottle test». After the «Bottle test» procedure, the remained water was separated by using a demulsifier (Backer F46). Suspended metal compounds were not separated from converted oil. Furthermore, the converted oil product undergoes atmospheric distillation to remove naptha fraction at (I.B.P.-200 ° C) [21]. Determination of the component composition of the «naptha-free converted oil» is carried out by precipitating asphaltenes, using 40-fold excess volume of mixture of alkanes, boiling at a temperature range of 40–70 º C. After precipitating asphaltenes from the sample, resin and oil (saturates) fractions were separated by liquid adsorption chromatography on silica gel. For the extraction of saturates the mixture of n-alkanes was used, for the extraction of resins mixture of isopropyl alcohol and benzene with 1 : 1 ratio was used. The study of the hydrocarbon composition of the saturated fractions of the converted oil was performed on the chromatograph Auto System XL, «PerkinElmer company» using a flame ionization detector (FID) and high performance quartz capillary column with a phase layer of SE 30 (length 25 m, inner diameter 0.2 mm). Technological parameters: isothermal condition, 1 min at an initial temperature of 60°C, heating rate 10°C/min to a temperature of 280°C, isothermal condition of 10 min. Rheological studies of the oil samples were carried out using the "cone- plate" system at the shear rate ranging from 3 to 1312 s-1, at a temperature range of 20 to 40 °С. The measured shear stress and the shear rate are used to calculate dynamic viscosity η, mPa·s. Afterwards, the rheological curves of viscosity – shear stress (η -τ) relation. were plotted. Based on the flow curves for each temperature, the following characteristics were determined: plastic viscosity (ηmax), Newtonian viscosity flow (ηmin) and the index of viscosity anomaly (θ = ηmax / ηmin), which characterizes the strength of the structure to shear deformations. The transformation of the colloidal structure of crude oil was evaluated by the change 4
of activation energy of viscous flow Ea, at the given shear rates and temperatures. It is calculated based on the Arrhenius dependence of the logarithm of viscosity on inverse temperature. tg α = For stable systems, this dependence has a linear behaviour, while the change in the slope of the curve would indicate phase transitions in colloidal system. Elemental composition of rocks before and after the experiments was determined by combustion of batches weighing 0.1 g in semi-automatic analyzer CHN-3 at a temperature of 1000°C.
3. Results and discussion The results of these studies show a significant effect of temperature and pressure on composition and properties of the converted heavy biodegraded oil. With increasing temperature of the experiment to 365°C, the yield of distillate fractions boiling up to 200 and 350°C increases and, the content of the residue above 350°C decreases (Fig.2) Analysis of the component composition of the products indicates the predominance of cracking reactions over the reactions of polycondensation. The increase in the content of light fractions in the products of experiments is mainly due to thermal degradation of the resins. This is confirmed by the component compositions of the liquid products of conversion (Table 1). The «control» experiment allows us to exclude a significant influence of the process temperature and pressure, while interpreting the data obtained by the analysis of the end products of aquathermolysis of crude oil. In the context of crude oil aquathermolysis with suspended particles, the initial reagents represent a three phase system, consisting of solid phase – nano -sized particles of metal oxides, liquid phase – high-molecular components of oil, and steam. In this case, the destruction of crude oil compounds will mainly occur on the surface of mineral additives, having a large surface area and catalytic function. The laws of physical adsorption dominated at the beginning of experiments. Low temperature and high pressure in these experiments are favorable for physical adsorption. Partial structuring of monomolecular surface layer with decrease in the entropy of the adsorbed molecules can be observed on the surface of the additives. Asphalt-resinous substances due to their polarity are adsorbed on the surface of the additives and partially counterbalance the surface forces and reduce the surface tension. This leads to a shift in the equilibrium towards the monomolecular reactions of thermal decomposition of C-C bonds by radical chain mechanism. As the result, the chemical adsorption prevails over physical adsorption
with
increasing of the temperature in the experiment, therefore, the adsorbed substances - resinous oil compounds, enter into a chemical reaction with the adsorbent to form products of cracking on its the surface. Thus, there are two competing mechanisms, on the one hand, the increase in temperature 5
enhances the process of cracking of high-molecular compounds of crude oil, and on the other hand, increasing the temperature in the absence of high pressure reduces the probability of adsorption onto the surface of the additive. The greatest reduction of asphalt-resinous compounds occurs in the oil content. At a temperature of 350 ° C and a pressure of 11 MPa in the presence of 6% Al2O3 ,having a particle size of 40 nm, in Experiment 2 the decrease of resins at 53% rel. and asphaltene at 58% rel was observed. Resinous substances during degradation form more oils, as is evidenced by the increase in oil content up to 45 % compared to an increase of 23 % during the «control» experiment (Table 1). In similar thermobaric conditions, at a temperature of 350°C and pressure of 12 MPa, an Experiment 3 on aquathermolysis of crude oil using ZnO particles with the size of 40 nm, was carried out. Component composition and the output of the fuel fractions in the final product was similar to the end product of the «control» experiment, with a slight decrease in the content of asphaltene and a small increase in output fraction from I.B.P to 200°C, which can be explained by a high interfacial surface area of nanoscale particles. Thus, we can observe the catalytic activity of Al2O3 in cracking reactions of high molecular weight hydrocarbons of heavy crude oil at a temperature of 350 ° C and pressures above 10 MPa. When 5% hematite additive of a specific surface area of 5,736 m2/g was added to the crude oil in Experiment 1, with increase in temperature up to 375°C and pressure up to 20 MPa in the process, we observe that the content of asphaltenes is reduced from 7.7 to 3.6 wt%, the contents of low boiling fractions and saturated hydrocarbons increase by 30 % rel. and 10.5% rel. accordingly in the end product of aquathermolysis, compared to the end product of the «control» experiment. The main reason for that might be that at the temperature and pressure parameters of the experiment, specifically at a temperature of 375°C and a pressure of 20 MPa, the water is in a metastable subcritical condition. On the contrary, at lower temperature and pressure in the Experiment 4 with hematite particles, the component and the fractional composition of the converted oil are similar to those of the end product of the «control» experiment. This indicates the catalytic function of hematite in the cracking reactions of high-molecular compounds of biodegraded oil at high temperature of 375 ° C and high pressure of 20 MPa, characteristic to subcritical water conditions. In the chromatograms of saturated fractions of the converted oil, obtained after aquathermolysis, in contrast to the chromatogram of the original oil, there are peaks belonging to light isoprenoid hydrocarbons with component compositions ranging from іС13 to іС18 (Fig.3).
6
The presence of solid n-alkanes ranging from nС29 to nС33 in the end product of the Experiment 1 can testify to their formation in the presence of hematite particles at thermobaric conditions of the experiment. It should be noted that authors in the work [21] indicated the existence of high molecular weight alkanes in asphaltenic oil. Thus, it is possible to draw a conclusion on destruction of the asphaltene associates under the influence of hematite. In the second experiment with γ-Al2O3, particles at a temperature of 350 °C and pressure of 11 MPa, in the end product, the content of asphaltene also decreases, but at the same time high-molecular n-alkanes aren't formed, on the contrary, intensity of the peaks corresponding to acyclic isoprenoid increases and intensity of peaks corresponding to tri and tetracyclic tarpenes of the composition C23-C38 decreases, whereas, pentacyclic terpanes (hopanes) remain unchanged. Thus, in a case with γ-Al2O3, it is possible to speak about cracking of high molecular weight naphthenic hydrocarbons of homologous series of terpanes. The degree of carbonization (2,3% wt.) of the end products of the experiments conducted at relatively low pressures from 5.5 to 12 MPa with particles of zinc oxide, hematite and nickel carbonate is much higher than that of the intial oil (1,9% wt.), and is similar to the degree of carbonization (2,4 wt.%). of the product of «control» experiment. The contents of hydrogen and carbon in these products are much higher. Comparative analysis of the elemental composition of these products and the initial oil, indicates partial removal of at least two heteroatoms (oxygen and sulfur) in aquathermolysis at the described conditions, whereby nitrogen content remains unchanged at (0.4% wt.). Higher values of an indicator of H / C indicate higher aliphaticity of the products of experiments 3 and 4. Higher values of an indicator of Н / C show higher paraffinicity of samples 3 and 4 (Table 2). It proves the formation of paraffin hydrocarbons in the course of conversion due to destruction of hybrid high-molecular compounds or compounds with heteroatom. The opposite happens with products of experiments, where the catalytic activity of suspended particles of Al2O3 and Fe2O3 is observed. They, like the initial oil, are characterized by the lowest value of the indicator H/C, which indicates the presence in their composition of high-carbon substances. In these products content of sulfur decreases to a lesser extent, from 2,8 to 2,0% wt. For the end product of experiment 1 with Fe2O3 particles, nitrogen content, on the contrary, increases . Contents of hydrogen and carbon in the product of aquathermolysis of initial oil with Fe2O3 are much higher, 81,3 and 13,2% wt. respectively. The end product of aquathermolysis of oil with particles of Al2O3 differs by high content of oxygen (4,5% wt.). This can be explained by side reactions of oxidation of fragments of highmolecular compounds. Thus, there is an inverse relationship between the degree of carbonization and the content of oxygen , on the one side, and content of sulfur, on the other. Based on the elemental composition, it can be assumed that destruction of heteroatomic compounds has taken place with higher 7
conversion rate for samples 3 and 4. It is possible that formation of the gases containing heteroatoms also occurred, since the content of O and S elements has decreased in these samples, the content of N remained unchanged. The effect of thermobaric conditions on initial oil leads to decrease in its viscosity which is caused, first of all, by decrease in content of resins, and increase in distillate fractions (Fig.4). In all studied range of temperatures for samples of the converted oil decrease in effective viscosity is observed at a shift speed of Newtonian flow. The maximum decrease in viscosity is obtained in the end product of experiment 1 with particles of Fe2O3. Resinous-asphaltene substances are adsorbed on the surface of the particles, thus, metal oxides can act as nuclei formation centers of a new phase in the oil disperse system concentrated on resinousasphaltene substances. The mechanism of the transformation of high molecular weight hydrocarbons is a radical-chain type, reactions of cracking followed by the condensation of asphaltenes structures can be observed. Decrease in viscosity of the product of experiment 4 can be caused by formation of oil dispersed system with more compact, in comparison with initial oil, supramolecular structure that is capable of creating smaller resistance to the liquid movement. The end products of aquathermolysis compared to the product of the «control» experiment are characterized by lower viscosities as well as lower viscosity index anomalies, due to a decrease in the content of resinous-asphaltenic substances in experiments 1 and 2, and heteroatomic structures, which enhanced the intermolecular interaction. Structural viscosity of the samples (dashed line, Fig. 4) is defined by the content of resins and asphaltenes. These components under the influence of external factors are capable of forming instantly emerging and collapsing associates with coagulationcrystallization type spatial structure, whose strength depends on the balance of forces acting on the oil dispersed system at the moment. The gradient between structural and Newtonian viscosity reflects stability of structures in the end product of aquathermolysis of the initial oil with suspended metal oxide particles to shear deformations. High viscosity at a temperature of 10 °C of the end product of aquathermolysis of crude oil with Al2O3 particles, coupled with a decrease in the content of asphaltenes and an increase in naptha fraction, may be due to high content of polar oxygen-containing and sulfurcontaining compounds capable of forming associates, which provide the spatial structure of coagulationcrystallization type. Low viscosity products of experiments 3 and 4, with a relatively high content of resin-asphaltene compounds, indicate the formation of a dispersed phase with a more compact supramolecular structure, which leads to less resistance when moving. 8
To have the in-depth knowledge of the cause of changes in the rheological properties of the end products of aquathermolysis of initial oil, the parameter of “energy of activation of viscous flow” was used. It was calculated based on the molecular kinetic theory of liquids by J.Frenkel and the transition state theory by Eyring. Analyzing the dependence “shear rate-activation energy of viscous flow of the products”, one should note the tendency of monotonous decrease of the module of the change in activation energy of viscous flow. It should be mentioned, that the value of the activation energy of the structural viscosity at temperatures ranging from 50 to 70 ° C differs from the general trend, which is explained by the increase in energy consumption for the destruction of the spatial structure built by associates of resin-asphaltene substances.
4. Conclusions Substantial amount of scientific, experimental data obtained from conventional oilfield development has been accumulated in the world. Theoretical and practical issues related to the development of unconventional resources of hydrocarbon deposits have been resolved to a lesser degree. The deposits of heavy crude oil are at the stage of their pilot testing, meanwhile, the deposits of biodegraded oil, still left untouched under the ground, are at their scientific research stage The results of the conducted research contribute to the development of theoretical model of conversion of biodegraded oil during hydrothermal processes in the presence of nano-sized particles of metal oxides. They facilitate the advancement of science in the process engineering of recovery of heavy crude from the rock and upgrading of their composition during full-field development. As the result of the research conducted it is established that aquathermolysis of heavy oil in the presence of metal oxides, at temperatures up to 380 °C and pressure up to 22 MPa, leads to decrease in viscosity of the obtained oil and increase in the content of saturated hydrocarbons and yield of light fractions. Converted oils during 3rd and 4th experiments have low viscosity in comparison with initial oil, and are characterized by more flat viscosity-temperature curves.
Acknowledgements The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University. This work was funded by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities.
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MFC-103 – N2-gas flow measuring device (up to 100 ml/ min of N2-gas); Т-101 - a heated tank with a stirring device (magnetic stirrer with 4-bladed turbine impeller); Н-103 – external electric heater (up to 500°С); С-102 – water cooler; Р-104 – pump ( up to 0,01-20 ml/min pump capacity); S-101 –2 litervolume separator Fig.1. The laboratory –scale plant for Aquathermolysis experiments
12
Fig. 2. Fractional composition of the initial oil and liquid products for experiments 1, 2, 3, 4
13
Fig. 3. Chromatograms Chromatogram of initial oil 1) and of tests end products: 2) 1 exp., 3) 2 exp.
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θ – index of viscosity anomaly; н – viscosity of Newtonian flow of liquid; с – structural viscosity
solid line – change of activation energy of Newtonian viscosity dashed line – change of activation energy of structural viscosity control – control experiment products, 1, 2, 3, 4 – end-products of experiments 1, 2, 3, 4 Fig. 4. Rheological properties of initial oil and converted oil:
15
Table 1 – General characteristics and component composition of heavy oil and end products Composition of reaction mass Initialoil Oil : water, 2 : 1, check 1. Oil : water, 1 : 1, Fe2O3, 6 wt. % 2. Oil : water, 1 : 1, Al2O3, 6 wt. % 3. Oil : water, 1 : 1, ZnO, 5 wt. % 4. Oil : water, 4 : 1, Ni, 3 wt. %, Fe, 4 wt. %.
Experimental conditions Т, °С
Р, MPa
distillate IBP 200°С, wt % of crude
-
-
9,4
54,5
37,8
7,7
365
5,5
10,2
67.05
25.85
7.1
375
20
13,3
74.1
22.3
3.6
350
11
12,5
79.4
17.4
3.2
350
12
12,9
67.03
26.27
6.3
350
8
11,6
68.00
25..2
6.8
* Chemical composition, wt. % Oils
Resins
Asphaltenes
* Component composition of stripped samples of oil, boiling above 200°С
Table 2- Elemental composition of the reaction mass Element composition, wt%
Composition of the reaction mass C
H
S
N
H/C
Initial oil
80,6
12,8
2,8
0,4
1,9
Oil,water, control
82,5
16,6
-
0,4
2,4
1 Oil, water, Fe2O3,nm
81,3
13,2
1,8
0,5
1,9
2 Oil, water, Al2O3, nm
80,1
12,8
2,0
0,6
1,9
3 Oil, water, ZnO, nm
81,8
15,6
-
0,4
2,3
4 Oil, water, Ni+2, Fe+2 * Calculated
82,2
15,7
-
0,4
2,3
16
PII: DOI: Reference:
S0920-4105(17)30344-3 http://dx.doi.org/10.1016/j.petrol.2017.02.015 PETROL3879
To appear in: Journal of Petroleum Science and Engineering Received date: 25 July 2016 Revised date: 7 February 2017 Accepted date: 22 February 2017 Cite this article as: Alfiya Lakhova, Sergey Petrov, Dina Ibragimova, Galina Kayukova, Aliya Safiulina, Alexey Shinkarev and Rachael Okekwe, AQUATHERMOLYSIS OF HEAVY OIL USING NANO OXIDES OF M E T A L S , Journal of Petroleum Science and Engineering, http://dx.doi.org/10.1016/j.petrol.2017.02.015 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting galley proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
AQUATHERMOLYSIS OF HEAVY OIL USING NANO OXIDES OF METALS Alfiya Lakhova¹, Sergey Petrov¹,²,Dina Ibragimova ¹,², Galina Kayukova², ³, Aliya Safiulina¹, Alexey Shinkarev³,Rachael Okekwe ¹
¹Kazan National Research Technological University, 420015, Russia, Kazan, Karl Marx St., 68, ²Kazan Federal University, 420008, Russia, Kazan, Kremlevskaya str., 18, ³A.E. Arbuzov Institute of Organic and Physical Chemistry Kazan Scientific Center, Russian Academy of Sciences, 420088, Russia, Kazan, Arbuzov st., 8 E-mail: [email protected], [email protected], [email protected]
The effect of suspended nanoparticles of magnetite and hematite on thermal decomposition of heavy oil at a temperature of 360 ° C in a vapor medium at different system pressures is revealed. The preferential destruction reactions of macromolecular components of oil, which lead to the reduction of oil viscosity, are established. The effect of zinc and aluminum oxides as additives initiating cracking of hydrocarbon bonds is studied. The changes in structure of the component of the converted products, as compared to the original crude oil, are obtained. Conducting the process in the presence of additives at a pressure of 11 MPa led to the reduction of the aromaticity of the final products, increase in the yield of hydrocarbon oils and the formation of gaseous products. It is observed that the amount of asphalt-resinous substances is reduced as the result of their conversion in the presence of additives. Rheological curves of conversion products are obtained, based on them the peculiarities of viscosity-temperature characteristics change can be shown. Keywords: homogeneous catalysis, high-viscosity oil, Nano-sized particles, iron oxides, the component composition of oil, rheological curve.
1. Introduction In modern refineries, the proportion of heavy oil in total volume increases every year. It is reported by the International Energy Agency that the worldwide resources of heavy oil are around 6 trillion barrels, which are mainly located in Canada, Venezuela, Russia and the USA. A review on recent advances on non-catalytic and catalytic process technologies for upgrading of heavy oils and residues is given in the article [1]. Therefore, there is a crucial need for new upgrading technologies that would provide them with a cost-effective development based on an efficient process technology and enhancement of catalytic systems. Catalytic performance can be improved by the use of various transition 1
metal precursors, additives, preparation techniques, use of other non-conventional metals, new active phases (carbides, nitrides etc.) and promoters, modifying of supports[2]. As many authors have noted [2]– [4], the development of catalytic systems has undergone two main stages: heterogeneous solid phasestage and homogeneous dispersed phase-stage. The homogeneous dispersed catalysts are divided into water-soluble (Mo, Ni oxide with aqueous ammonia of Chevron Inc.; Mo, V and Fe metal oxide or salt and heteropoly acid of UOP Co.; Ni, Fe, Mo and Fe-Co liquid catalyst of Petro China Company Limited; Phosphomolybdic acid ammonium heptamolybdate molybdenum oxalate of Exxon Research and Engineering Co. etc.),and oil-soluble (Mo or W salts of fatty acids of Chevron Inc.;CrO3tert-butyl alcohol, Molybdenum alicyclic or naphthenate, Fe2O3 and Mo naphthenate of Exxon Research and Engineering Co.; Iron pentacarbonyl or molybdenum 2-ethylhexanoate of Alberta Oil Sands Technology and Research Authority etc.) [2]. One of the key and promising areas is in using nano-scale catalysts. They have significant advantages, namely large surface area in the absence of the porous structure, which could be plugged with coke, high stability of activity and the elimination of diffusion control in the heavy oil feedstock. In the article by Canadian scientists the catalytic activity of micro particles and nanoparticles of nickel in the thermolysis reactions of Athabasca oil is compared. The authors found a significant reduction in viscosity of the converted products with nano-sized particles, apparently due to greater catalytic surface area [5]. It was proposed that nano-nickel catalyst in the aquathermolysis of extra-heavy oil San56-13-19 accelerated the pyrolysis of asphaltene, which led to the production of O-containing substances and, therefore to the reduction of viscosity up to 90.36% [6]. Hydrocracking of heavy residue in the presence of dispersed colloidal catalyst (nanosheet-structured WS2) was compared with those of bulk WS2 and MoS2. The single-layer WS2 catalyst provided high yield of fuel (45.4 wt.%) and asphaltene conversion (75.3 wt.%) [7]. Most common active catalyst components are salts of various metals, such as chlorides, sulphates, nitrates of nickel, iron, cobalt [8], [9]. iron derivatives (sulfates, naphtenates, sulfonates etc.) as catalysts have comparatively low costs. It was reported that Tris (acetylacetonato) iron (III) forms magnetic nanoparticles during aquathermolysis of heavy oil and leads to deep conversion of resins into light components [10]. Most common precursors for catalysts are molybdates [11]–[13]. Metallic oxide nanoparticles [14], [15] are widely used as precursors. A MoO3-deep eutectic solvent (DES) catalyst precursor, used in aquathermolysis, provided the reduction of viscosity of heavy oil by 43 % [16]. At high temperatures the metallic salts decompose to oxides, which tend to form sulfides in the presence of hydrogen sulfide. Comparative experiments on the resins and asphaltenes conversion of Liaohe oil showed that the conversion degree is higher in the presence of oil-soluble catalyst precursor – naphthenates of Ni and Fe, rather than sulphates of these metals [17]. Similar observations were made in 2
the study of complex compounds of iron and Gemini surfactants [18]. During the heavy oil conversion process at 170 ° C for 24 hours in the presence of Fe2(SO4)3 [19], the decrease in viscosity amounted to 69%, whereas in the presence of iron naphthenate – up to 83%. The research aimed to produce efficient and inexpensive catalytic systems for upgrading of heavy hydrocarbon resources is of high priority nowadays. There is a crucial need for in-depth knowledge of the nature of the thermal catalytic conversion of heavy oils in relation to its composition and the presence of various nano-sized oxide particles in it. Therefore, optimum technologies, aimed at improving the efficiency of development of specific heavy crude oil deposits, can be successfully selected. The present work is devoted to identifying the changes in the hydrocarbon composition and rheological characteristics of the products of aquathermolysis of the biodegraded heavy crude oil, depending on its content of iron oxides nanoparticles, aluminum, zinc, as well as nickel carbonate at various temperature and pressure conditions.
2. Experimental Procedure 2.1. Raw materials (Objects) The object of the research is the biodegraded heavy crude oil from carbonate rock, found in Ashal’cha oil field in the Republic of Tatarstan. The density of the heavy crude oil under normal conditions is 0,9512 g/cm3. It is rich in resinous-asphaltene compounds (up to 45%) and sulphur (up to 4.8%), and has low content of light fractions boiling up to 350 ° C (up to 28%). N-alkanes are not present in it. Into the heavy crude oil, we added metal-containing substances, like hematite particles Fe2O3 (200nm), alumina γ-Al2O3 and ZnO, having a particle size up to 40 nm, stabilized with 4-methyl-2pentanone, and Nickel (II) carbonate, having a particle size up to 100 nm. The advantage of the finedispersed particles of metal oxides is their spatial accessibility to high-molecular compounds of heavy crude oil. Metal oxides were selected as components exhibiting catalytic activity, because they accelerate the breakdown of the С–S, С–С bonds, whilst hydrogenating metals enhance breakdown of С-О bonds of high-molecular components of the heavy crude oil. For instance, nickel carbonate accelerates the destructive hydrogenation reaction. Upon reaction with steam, metal oxides are reduced with the formation of magnetite and hydrogen according to the following mechanism: 3Fe + 4H2O = Fe3O4 + 4H2; hydrogen produced can participate in the hydrogenation reactions [20] 2.2. Aquathermolysis experiments The introduction of catalyst systems into bituminous oil is carried out through an aqueous phase. The aqueous suspension containing nano-sized particles was prepared by mechanical activation in 3
ultrasonic plant Il100-6/1-22/44 at a frequency of 22 kHz ultrasonic waves, and energy density of 5 W/cm². The plant capacity varies from 630 W up to 5 kW, at an operating frequency of 22 ± 10% кНz. Research on the thermal catalytic refining of oil was carried out in a laboratory batch reactor under isothermal conditions at high temperatures and pressures, the experiments lasted up to 3.5 hours. The plant is equipped with a heated autoclave of 2 liters with a motorized stirrer, a reservoir for collecting final products and a steam mixture supply module, which can measure and control mass flow (Fig. 1). The reaction mixture (crude oil, water, metal-containing compounds) with a total volume of 1 liter was loaded into the autoclave. The initial pressure corresponded to the atmospheric pressure, when the reaction mixture was heated up to 380°C, pressure increased up to 21 MPa. After the experiment, the reactor was allowed to cool naturally to room temperature to reduce the resulting overpressure.
2.3. Analysis of products The resulting product contained water, which was removed by standard method of «Bottle test». After the «Bottle test» procedure, the remained water was separated by using a demulsifier (Backer F46). Suspended metal compounds were not separated from converted oil. Furthermore, the converted oil product undergoes atmospheric distillation to remove naptha fraction at (I.B.P.-200 ° C) [21]. Determination of the component composition of the «naptha-free converted oil» is carried out by precipitating asphaltenes, using 40-fold excess volume of mixture of alkanes, boiling at a temperature range of 40–70 º C. After precipitating asphaltenes from the sample, resin and oil (saturates) fractions were separated by liquid adsorption chromatography on silica gel. For the extraction of saturates the mixture of n-alkanes was used, for the extraction of resins mixture of isopropyl alcohol and benzene with 1 : 1 ratio was used. The study of the hydrocarbon composition of the saturated fractions of the converted oil was performed on the chromatograph Auto System XL, «PerkinElmer company» using a flame ionization detector (FID) and high performance quartz capillary column with a phase layer of SE 30 (length 25 m, inner diameter 0.2 mm). Technological parameters: isothermal condition, 1 min at an initial temperature of 60°C, heating rate 10°C/min to a temperature of 280°C, isothermal condition of 10 min. Rheological studies of the oil samples were carried out using the "cone- plate" system at the shear rate ranging from 3 to 1312 s-1, at a temperature range of 20 to 40 °С. The measured shear stress and the shear rate are used to calculate dynamic viscosity η, mPa·s. Afterwards, the rheological curves of viscosity – shear stress (η -τ) relation. were plotted. Based on the flow curves for each temperature, the following characteristics were determined: plastic viscosity (ηmax), Newtonian viscosity flow (ηmin) and the index of viscosity anomaly (θ = ηmax / ηmin), which characterizes the strength of the structure to shear deformations. The transformation of the colloidal structure of crude oil was evaluated by the change 4
of activation energy of viscous flow Ea, at the given shear rates and temperatures. It is calculated based on the Arrhenius dependence of the logarithm of viscosity on inverse temperature. tg α = For stable systems, this dependence has a linear behaviour, while the change in the slope of the curve would indicate phase transitions in colloidal system. Elemental composition of rocks before and after the experiments was determined by combustion of batches weighing 0.1 g in semi-automatic analyzer CHN-3 at a temperature of 1000°C.
3. Results and discussion The results of these studies show a significant effect of temperature and pressure on composition and properties of the converted heavy biodegraded oil. With increasing temperature of the experiment to 365°C, the yield of distillate fractions boiling up to 200 and 350°C increases and, the content of the residue above 350°C decreases (Fig.2) Analysis of the component composition of the products indicates the predominance of cracking reactions over the reactions of polycondensation. The increase in the content of light fractions in the products of experiments is mainly due to thermal degradation of the resins. This is confirmed by the component compositions of the liquid products of conversion (Table 1). The «control» experiment allows us to exclude a significant influence of the process temperature and pressure, while interpreting the data obtained by the analysis of the end products of aquathermolysis of crude oil. In the context of crude oil aquathermolysis with suspended particles, the initial reagents represent a three phase system, consisting of solid phase – nano -sized particles of metal oxides, liquid phase – high-molecular components of oil, and steam. In this case, the destruction of crude oil compounds will mainly occur on the surface of mineral additives, having a large surface area and catalytic function. The laws of physical adsorption dominated at the beginning of experiments. Low temperature and high pressure in these experiments are favorable for physical adsorption. Partial structuring of monomolecular surface layer with decrease in the entropy of the adsorbed molecules can be observed on the surface of the additives. Asphalt-resinous substances due to their polarity are adsorbed on the surface of the additives and partially counterbalance the surface forces and reduce the surface tension. This leads to a shift in the equilibrium towards the monomolecular reactions of thermal decomposition of C-C bonds by radical chain mechanism. As the result, the chemical adsorption prevails over physical adsorption
with
increasing of the temperature in the experiment, therefore, the adsorbed substances - resinous oil compounds, enter into a chemical reaction with the adsorbent to form products of cracking on its the surface. Thus, there are two competing mechanisms, on the one hand, the increase in temperature 5
enhances the process of cracking of high-molecular compounds of crude oil, and on the other hand, increasing the temperature in the absence of high pressure reduces the probability of adsorption onto the surface of the additive. The greatest reduction of asphalt-resinous compounds occurs in the oil content. At a temperature of 350 ° C and a pressure of 11 MPa in the presence of 6% Al2O3 ,having a particle size of 40 nm, in Experiment 2 the decrease of resins at 53% rel. and asphaltene at 58% rel was observed. Resinous substances during degradation form more oils, as is evidenced by the increase in oil content up to 45 % compared to an increase of 23 % during the «control» experiment (Table 1). In similar thermobaric conditions, at a temperature of 350°C and pressure of 12 MPa, an Experiment 3 on aquathermolysis of crude oil using ZnO particles with the size of 40 nm, was carried out. Component composition and the output of the fuel fractions in the final product was similar to the end product of the «control» experiment, with a slight decrease in the content of asphaltene and a small increase in output fraction from I.B.P to 200°C, which can be explained by a high interfacial surface area of nanoscale particles. Thus, we can observe the catalytic activity of Al2O3 in cracking reactions of high molecular weight hydrocarbons of heavy crude oil at a temperature of 350 ° C and pressures above 10 MPa. When 5% hematite additive of a specific surface area of 5,736 m2/g was added to the crude oil in Experiment 1, with increase in temperature up to 375°C and pressure up to 20 MPa in the process, we observe that the content of asphaltenes is reduced from 7.7 to 3.6 wt%, the contents of low boiling fractions and saturated hydrocarbons increase by 30 % rel. and 10.5% rel. accordingly in the end product of aquathermolysis, compared to the end product of the «control» experiment. The main reason for that might be that at the temperature and pressure parameters of the experiment, specifically at a temperature of 375°C and a pressure of 20 MPa, the water is in a metastable subcritical condition. On the contrary, at lower temperature and pressure in the Experiment 4 with hematite particles, the component and the fractional composition of the converted oil are similar to those of the end product of the «control» experiment. This indicates the catalytic function of hematite in the cracking reactions of high-molecular compounds of biodegraded oil at high temperature of 375 ° C and high pressure of 20 MPa, characteristic to subcritical water conditions. In the chromatograms of saturated fractions of the converted oil, obtained after aquathermolysis, in contrast to the chromatogram of the original oil, there are peaks belonging to light isoprenoid hydrocarbons with component compositions ranging from іС13 to іС18 (Fig.3).
6
The presence of solid n-alkanes ranging from nС29 to nС33 in the end product of the Experiment 1 can testify to their formation in the presence of hematite particles at thermobaric conditions of the experiment. It should be noted that authors in the work [21] indicated the existence of high molecular weight alkanes in asphaltenic oil. Thus, it is possible to draw a conclusion on destruction of the asphaltene associates under the influence of hematite. In the second experiment with γ-Al2O3, particles at a temperature of 350 °C and pressure of 11 MPa, in the end product, the content of asphaltene also decreases, but at the same time high-molecular n-alkanes aren't formed, on the contrary, intensity of the peaks corresponding to acyclic isoprenoid increases and intensity of peaks corresponding to tri and tetracyclic tarpenes of the composition C23-C38 decreases, whereas, pentacyclic terpanes (hopanes) remain unchanged. Thus, in a case with γ-Al2O3, it is possible to speak about cracking of high molecular weight naphthenic hydrocarbons of homologous series of terpanes. The degree of carbonization (2,3% wt.) of the end products of the experiments conducted at relatively low pressures from 5.5 to 12 MPa with particles of zinc oxide, hematite and nickel carbonate is much higher than that of the intial oil (1,9% wt.), and is similar to the degree of carbonization (2,4 wt.%). of the product of «control» experiment. The contents of hydrogen and carbon in these products are much higher. Comparative analysis of the elemental composition of these products and the initial oil, indicates partial removal of at least two heteroatoms (oxygen and sulfur) in aquathermolysis at the described conditions, whereby nitrogen content remains unchanged at (0.4% wt.). Higher values of an indicator of H / C indicate higher aliphaticity of the products of experiments 3 and 4. Higher values of an indicator of Н / C show higher paraffinicity of samples 3 and 4 (Table 2). It proves the formation of paraffin hydrocarbons in the course of conversion due to destruction of hybrid high-molecular compounds or compounds with heteroatom. The opposite happens with products of experiments, where the catalytic activity of suspended particles of Al2O3 and Fe2O3 is observed. They, like the initial oil, are characterized by the lowest value of the indicator H/C, which indicates the presence in their composition of high-carbon substances. In these products content of sulfur decreases to a lesser extent, from 2,8 to 2,0% wt. For the end product of experiment 1 with Fe2O3 particles, nitrogen content, on the contrary, increases . Contents of hydrogen and carbon in the product of aquathermolysis of initial oil with Fe2O3 are much higher, 81,3 and 13,2% wt. respectively. The end product of aquathermolysis of oil with particles of Al2O3 differs by high content of oxygen (4,5% wt.). This can be explained by side reactions of oxidation of fragments of highmolecular compounds. Thus, there is an inverse relationship between the degree of carbonization and the content of oxygen , on the one side, and content of sulfur, on the other. Based on the elemental composition, it can be assumed that destruction of heteroatomic compounds has taken place with higher 7
conversion rate for samples 3 and 4. It is possible that formation of the gases containing heteroatoms also occurred, since the content of O and S elements has decreased in these samples, the content of N remained unchanged. The effect of thermobaric conditions on initial oil leads to decrease in its viscosity which is caused, first of all, by decrease in content of resins, and increase in distillate fractions (Fig.4). In all studied range of temperatures for samples of the converted oil decrease in effective viscosity is observed at a shift speed of Newtonian flow. The maximum decrease in viscosity is obtained in the end product of experiment 1 with particles of Fe2O3. Resinous-asphaltene substances are adsorbed on the surface of the particles, thus, metal oxides can act as nuclei formation centers of a new phase in the oil disperse system concentrated on resinousasphaltene substances. The mechanism of the transformation of high molecular weight hydrocarbons is a radical-chain type, reactions of cracking followed by the condensation of asphaltenes structures can be observed. Decrease in viscosity of the product of experiment 4 can be caused by formation of oil dispersed system with more compact, in comparison with initial oil, supramolecular structure that is capable of creating smaller resistance to the liquid movement. The end products of aquathermolysis compared to the product of the «control» experiment are characterized by lower viscosities as well as lower viscosity index anomalies, due to a decrease in the content of resinous-asphaltenic substances in experiments 1 and 2, and heteroatomic structures, which enhanced the intermolecular interaction. Structural viscosity of the samples (dashed line, Fig. 4) is defined by the content of resins and asphaltenes. These components under the influence of external factors are capable of forming instantly emerging and collapsing associates with coagulationcrystallization type spatial structure, whose strength depends on the balance of forces acting on the oil dispersed system at the moment. The gradient between structural and Newtonian viscosity reflects stability of structures in the end product of aquathermolysis of the initial oil with suspended metal oxide particles to shear deformations. High viscosity at a temperature of 10 °C of the end product of aquathermolysis of crude oil with Al2O3 particles, coupled with a decrease in the content of asphaltenes and an increase in naptha fraction, may be due to high content of polar oxygen-containing and sulfurcontaining compounds capable of forming associates, which provide the spatial structure of coagulationcrystallization type. Low viscosity products of experiments 3 and 4, with a relatively high content of resin-asphaltene compounds, indicate the formation of a dispersed phase with a more compact supramolecular structure, which leads to less resistance when moving. 8
To have the in-depth knowledge of the cause of changes in the rheological properties of the end products of aquathermolysis of initial oil, the parameter of “energy of activation of viscous flow” was used. It was calculated based on the molecular kinetic theory of liquids by J.Frenkel and the transition state theory by Eyring. Analyzing the dependence “shear rate-activation energy of viscous flow of the products”, one should note the tendency of monotonous decrease of the module of the change in activation energy of viscous flow. It should be mentioned, that the value of the activation energy of the structural viscosity at temperatures ranging from 50 to 70 ° C differs from the general trend, which is explained by the increase in energy consumption for the destruction of the spatial structure built by associates of resin-asphaltene substances.
4. Conclusions Substantial amount of scientific, experimental data obtained from conventional oilfield development has been accumulated in the world. Theoretical and practical issues related to the development of unconventional resources of hydrocarbon deposits have been resolved to a lesser degree. The deposits of heavy crude oil are at the stage of their pilot testing, meanwhile, the deposits of biodegraded oil, still left untouched under the ground, are at their scientific research stage The results of the conducted research contribute to the development of theoretical model of conversion of biodegraded oil during hydrothermal processes in the presence of nano-sized particles of metal oxides. They facilitate the advancement of science in the process engineering of recovery of heavy crude from the rock and upgrading of their composition during full-field development. As the result of the research conducted it is established that aquathermolysis of heavy oil in the presence of metal oxides, at temperatures up to 380 °C and pressure up to 22 MPa, leads to decrease in viscosity of the obtained oil and increase in the content of saturated hydrocarbons and yield of light fractions. Converted oils during 3rd and 4th experiments have low viscosity in comparison with initial oil, and are characterized by more flat viscosity-temperature curves.
Acknowledgements The work is performed according to the Russian Government Program of Competitive Growth of Kazan Federal University. This work was funded by the subsidy allocated to Kazan Federal University for the state assignment in the sphere of scientific activities.
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MFC-103 – N2-gas flow measuring device (up to 100 ml/ min of N2-gas); Т-101 - a heated tank with a stirring device (magnetic stirrer with 4-bladed turbine impeller); Н-103 – external electric heater (up to 500°С); С-102 – water cooler; Р-104 – pump ( up to 0,01-20 ml/min pump capacity); S-101 –2 litervolume separator Fig.1. The laboratory –scale plant for Aquathermolysis experiments
12
Fig. 2. Fractional composition of the initial oil and liquid products for experiments 1, 2, 3, 4
13
Fig. 3. Chromatograms Chromatogram of initial oil 1) and of tests end products: 2) 1 exp., 3) 2 exp.
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θ – index of viscosity anomaly; н – viscosity of Newtonian flow of liquid; с – structural viscosity
solid line – change of activation energy of Newtonian viscosity dashed line – change of activation energy of structural viscosity control – control experiment products, 1, 2, 3, 4 – end-products of experiments 1, 2, 3, 4 Fig. 4. Rheological properties of initial oil and converted oil:
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Table 1 – General characteristics and component composition of heavy oil and end products Composition of reaction mass Initialoil Oil : water, 2 : 1, check 1. Oil : water, 1 : 1, Fe2O3, 6 wt. % 2. Oil : water, 1 : 1, Al2O3, 6 wt. % 3. Oil : water, 1 : 1, ZnO, 5 wt. % 4. Oil : water, 4 : 1, Ni, 3 wt. %, Fe, 4 wt. %.
Experimental conditions Т, °С
Р, MPa
distillate IBP 200°С, wt % of crude
-
-
9,4
54,5
37,8
7,7
365
5,5
10,2
67.05
25.85
7.1
375
20
13,3
74.1
22.3
3.6
350
11
12,5
79.4
17.4
3.2
350
12
12,9
67.03
26.27
6.3
350
8
11,6
68.00
25..2
6.8
* Chemical composition, wt. % Oils
Resins
Asphaltenes
* Component composition of stripped samples of oil, boiling above 200°С
Table 2- Elemental composition of the reaction mass Element composition, wt%
Composition of the reaction mass C
H
S
N
H/C
Initial oil
80,6
12,8
2,8
0,4
1,9
Oil,water, control
82,5
16,6
-
0,4
2,4
1 Oil, water, Fe2O3,nm
81,3
13,2
1,8
0,5
1,9
2 Oil, water, Al2O3, nm
80,1
12,8
2,0
0,6
1,9
3 Oil, water, ZnO, nm
81,8
15,6
-
0,4
2,3
4 Oil, water, Ni+2, Fe+2 * Calculated
82,2
15,7
-
0,4
2,3
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