Cracking Of Heavy Oil Research Articles

Effective cracking of heavy crude oil by using shock-induced nanobubble collapse: A molecular dynamics study

We investigate molecular mechanisms of hydrocarbon cracking in heavy crude oil promoted by nanobubble collapse due to ultrasound-originated shock wave. Our millions-atom molecular dynamics simulations reveal rapid flow of molecules, causing nanobubble collapse and formation of energetic nanojet with a mushroom-like shape. The nanojet apex exhibits extremely high temperature before and just after the bubble collapse, which makes a favorable condition for effective cracking of paraffin molecules. The cracking rate and portion of nanobubble-containing systems are larger than those of perfect system before the bubble collapse, and larger size of nanobubble is preferable for the cracking. The cracking efficiency is improved for the paraffin molecules with longer carbon chain.

INFLUENCE OF MODIFICATION OF KAOLINITES BY ALUMINUM OXIDE ON THE CRACKING ACTIVITY OF PETROLEUM RESIDUE

The preparation of matrices of zeolite-containing catalysts using acid-treated (20% H2SO4) kaolinites from the Pavlodar region of Kazakhstan (NPK-1, NPK-2 and NPK-3) with subsequent modification with aluminum hydroxo complexes of different concentrations (2.5, 5.0 and 7.5 mmol Al3+/g) was studied. and aluminum hydroxide gel prepared by the ammonia method for activity in cracking residual petroleum feedstock. In the experimental part of the article for kaolinites of the Pavlodar region of Kazakhstan - PK-1, PK-2 and PK-3, the values of the SiO2/Al2O3 molar ratios in the original samples, the change in these ratios during acid activation and subsequent modification with aluminum hydroxo complexes are considered. It has been shown that the criterion for choosing kaolinites as matrices for zeolite catalysts can be the increased content of aluminum oxide in the original kaolinite. From the analysis of data on the matrix activity of kaolinites in the cracking of vacuum gas oil, it follows that in order to achieve optimal yields of gasoline and light gas oil for samples with lower Al2O3 content, the introduction of a higher concentration of hydroxo complex is required. Using the example of the Al(2.5)NPK-1 sample, it is shown that the additional introduction of aluminum hydroxide gel (5% Al2O3 by weight of the catalyst) obtained by the ammonia method into the modified kaolinite matrix, followed by drying and heat treatment leads to the production of a catalyst with high activity. The catalyst was tested in the cracking of fuel oil, a mixture of vacuum gas oil (VG) with fuel oil (30%). For comparison, data on cracking of heavy vacuum gas oil are presented. Gasoline yields for these types of raw materials at 5000C are 26.8; 31.9 and 39.1%; respectively, with raw material conversion of 88.4% and 92.1%. Cracking gasolines are characterized by a high content of iso-paraffin and aromatic hydrocarbons. Al(2.5)NPK-1+Al2O3 can be an economically beneficial and environmentally friendly catalyst and adsorbent.

In-situ hydrothermal upgrading and mechanism of heavy oil with nano-Fe2O3 in the porous media

Hydrothermal upgrading is a promising technology for heavy oil, yet the impact of reservoir conditions on the catalytic effect of catalysts and the pathway are not clear. In this study, the effect of the formation environment on the catalytic upgrading process was investigated through simulating the reservoir conditions (2000 mD permeability, 25 % porosity) for catalytic hydrothermal cracking of heavy oil. Under the hydrothermal upgrading conditions（240 ℃, 24 h, 50 wt%, 0.1 wt% nano-Fe2O3）, 9.15 % of the heavy component(5.1 % resin and 4.05 % asphaltene) was converted to light component. The content of hydrocarbons below C17 in the saturated fraction increased from 36.29 % to 59.85 %. The structure of the asphaltene was disrupted resulting in a lower level of asphaltene stacking, and NC/NH ratio increased 13.61 % compared to heavy oil. In addition, the reservoir condition with quartz as the supporting medium improved the catalytic ability of iron oxide nanoparticles. When injected into the reservoir medium, nano-size facilitated dispersion on the surface of the proppant and inhibited the aggregation of nanoparticles, which ensured the continuous operation of the active sites on the surface of the catalyst. Electron transfer of Fe2+/Fe3+ catalyzed the heterolytic cleavage of covalent bonds of H2O/heavy oil molecules was the mechanism for heavy oil upgrading. These findings demonstrated the feasibility of in-situ upgrading of heavy oil through the use of nano-catalysts under reservoir conditions.

Study on the pathways of thermochemical sulfate reduction between sulfates and alkanes at low temperatures

To reduce the energy consumption of heavy oil thermal recovery, low-temperature hot water flooding is becoming popular. The occurrence of thermochemical sulfate reduction (TSR) reactions during the hot water flooding process generates H2S, which can corrode equipment and jeopardize personnel safety. Preventing and managing H2S requires studying TSR reactions. The study investigated the reactivity of SO42-, HSO4-, and [MgSO4]CIP in the TSR reaction during heavy oil low-temperature hot water flooding. The results indicated that during low-temperature hot water flooding, no significant thermal cracking of heavy oil occurs, only a minor aquathermolysis takes place, while the TSR reaction proceeds vigorously. The TSR reaction leads to increased yields of H2S, CH4, and CO2, as well as a higher S content in the heavy oil. Based on experimental results, numerical simulations of the reaction process between SO42- and CH4 were conducted using density functional theory and transition state theory. The results indicated that the reduction of SO42- to produce SO32- is the rate-limiting step in the entire reaction pathway between SO42- and CH4. Further analysis of the reaction barriers and chemical reaction rates of the three sulfates (SO42-, HSO4-, and [MgSO4]CIP) and C1-C5 alkanes was conducted based on the limiting step. Through macro and micro analysis, this study not only confirmed previous findings regarding the order of alkanes participating in TSR reactions from the perspective of microscopic molecular but also clarified the oxidation order of sulfate species under heavy oil low-temperature thermal water flooding conditions, with the sequence being HSO4- > [MgSO4]CIP>SO42-. This study provides a foundational understanding of TSR reactions during heavy oil low-temperature hot water flooding and is of significance for the prediction and management of H2S.

Solar-integrated binary chemical cracking of heavy oil for efficient high-order fuel transformation and extra hydrogen storage

Solar energy is an attractive alternative to fossil fuels (electricity and coke) for petroleum products generation. A solar-integrated binary chemical cracking of heavy oil system integrates solar energy into oil processing for carbon neutrality，in which pyrolysis and electrolysis benefit heavy oil conversion and hydrogen storage. This system has been studied in terms of solar chemical engineering, electrolyte engineering and electrode engineering. The results show improved hydrogen yield and cracking rate of heavy oil and a significant reduction in the operating temperature compared to catalytic cracking. The performance of molten salt electrolytes is as follows: binary NaOH–KOH > ternary KCl–LiCl + NaOH > ternary KCl–LiCl + NaHCO3. In electrode engineering, the electro-catalytic electrodes are in an order of Inconel 718> Ni > Incoloy 825 electrodes in the cracking rate, Ni > Inconel 718>Incoloy 825 electrodes in the hydrogen yield, and Incoloy 825>Inconel 718>Ni electrodes in the ability, for sustainable and stable efficient production.

Influence of a Precursor Catalyst on the Composition of Products in Catalytic Cracking of Heavy Oil

Heavy oils are characterized by a high content of resins and asphaltenes, which complicates refining and leads to an increase in the cost of refinery products. These components can be strongly adsorbed on the acid sites of a supported catalyst, leading to its deactivation. Currently, various salts of group 8 metals are being considered for such processes to act as catalysts during oil cracking. At the same time, the nature of the precursor often has a significant impact on the process of refining heavy oil. In this work, catalytic cracking of heavy oil from the Ashalchinskoye field using different precursors (nanodispersed catalysts formed in situ based on NiO) has been studied. The cracking was carried out at 450 °C with a catalyst content from 0.1 to 0.5 wt.%. The catalytic cracking products were analyzed via SARA, GC, XRD and SEM. Nickel acetate and nitrate promote similar yields of by-products, while formate promotes higher yields of gaseous products. Formate and nickel acetate were shown to produce 1.8 and 2.8 wt.% more light fractions than nickel nitrate. When heavy oil is cracked in the presence of Ni(NO3)2∙6H2O, the maximum decrease in sulfur content (2.12 wt.%) is observed compared to other precursors. It has been found that the composition and morphology of the resulting nickel sulfides and compaction products are influenced by the nature of the catalyst precursor. XRD and SEM analyses of coke-containing catalysts indicate the formation of Ni9S8 and Ni0.96S phases during cracking when nickel nitrate is used and the formation of NiS and Ni9S8 when nickel acetate and formate are used.

Co and Ni-containing catalysts for heavy oil refining: the effect of ethanol on the composition and structure of catalytic cracking products

The study deals with the products of thermal processing of heavy oil in the presence of Ni- and Co-containing catalysts that are formed in situ from the mixture of corresponding salts with ethanol. In comparison with thermal cracking, in the catalytic process the yield of bright fractions increases from 51 to 63 % and the yield of coke decreases from 3 to 2 wt.%. In the case of mixed Ni and Сo catalyst, the least yields of gas (5 wt.%) and coke (0.1 wt.%) are observed. A decrease in the sulfur content occurs in the products of both thermal (by 17 %) and catalytic cracking (from 12 to 32 rel.%) predominantly due to its removal as gaseous products. The structuralgroup characteristics of the averaged asphaltene molecules were studied before and after heavy oil cracking. XRD of solid cracking products was used to identify Ni0.96S, Ni9S8 and Co9S8 phases.

Oxalic acid as a hydrogen donor and its promotion on the catalytic viscosity reduction of heavy crude oil over Cu/FeOx catalyst

In this paper, Cu/FeOx composite catalysts were successfully synthesized by a hydrothermal method followed by a hydrogen gas reduction and were used as the catalysts for the cracking of heavy crude oil and the simultaneous low-temperature water–gas swift (LTWGS) reaction. Oxalic acid was used to generate the reactants (i.e., CO and H2O) of LTWGS reaction in-situ through its decomposition under the reaction temperature (200 ℃) of the heavy crude oil cracking. Cu0 in Cu/FeOx acted as a catalyst of the LTWGS reaction (CO + H2O ↔ CO2 + H2) and α-Fe2O3 in Cu/FeOx acted as a catalyst for the cracking of heavy crude oil. In-situ H2 coming from the LTWGS reaction promoted the catalytic viscosity reduction rate of heavy crude oil via inhibiting the radicals from recombining. This work gives a new, economical and efficient approach to supplying H2 for heavy crude oil upgrading through the in-situ LTWGS reaction of the decomposition products of oxalic acid.

Preparation of Surface-Active Hyperbranched-Polymer-Encapsulated Nanometal as a Highly Efficient Cracking Catalyst for In Situ Combustion of Heavy Oil.

In situ combustion of heavy oil is currently the most suitable thermal method that meets energy consumption and carbon dioxide emission requirements for heavy oil recovery. The combustion catalyst needs to perform multiple roles for application; it should be capable of catalyzing heavy oil combustion at high temperatures, as well as be able to migrate in the geological formation for injection. In this work, a hyperbranched polymer composite nanometal fluid was used as the injection vector for a heavy oil in situ combustion catalyst, which enabled the catalyst to rapidly migrate to the surface of the oil phase in porous media and promoted heavy oil cracking deposition at high temperatures. Platinum (Pt) nanoparticles encapsulated with cetyl-hyperbranched poly(amide-amine) (CPAMAM), with high interfacial activity, were synthesized by a facile phase-transfer method; the resulting material is called Pt@CPAMAM. Pt@CPAMAM has good dispersion, and as an aqueous solution, it can reduce the interfacial tension between heavy oil and water. As a catalyst, it can improve the conversion rate during the pyrolysis of heavy oil in a nitrogen atmosphere. The catalyst structure designed in this study is closer to that exhibited in practical geological formation applications, making it a potential method for preparing catalysts for use in heavy oil in situ combustion to resolve the problem of catalyst migration in the geological formation.

Cracking of Heavy Oil in Supercritical Water in the Presence of Iron Oxide Nanopowder: Asphaltene Transformations and Process Kinetics

The products of catalytic cracking of heavy crude oil from the Ashalchinskoye oil field (the Almetyevsk district of the Republic of Tatarstan, Russia) were characterized. The effects of a Fe2O3 nanopowder catalyst and the presence of supercritical water (SCW) on the composition and structure of these cracking products were investigated. Cracking over 0.01 wt % Fe2O3 nanopowder in a SCW environment was found to enhance the yield of distillates by more than 34 wt % and to reduce the content of resinous asphaltene materials by a factor of 2.1 compared to the initial crude oil. It was further shown that Fe2O3-nanopowder-catalyzed cracking produces coke-like asphaltenes with a low H/C atomic ratio (no higher than 0.75). Reaction rate constants were evaluated for the thermal and catalytic cracking of the heavy oil from the Ashalchinskoye field.

Optimization of Efficient Development Modes of Offshore Heavy Oil and Development Planning of Potential Reserves in China

Thermal recovery is still the most important means to increase heavy oil EOR. With the increase in the recovery factor and the difficulty of exploiting new exploration reserves, the efficient utilization of offshore heavy oil reserves has attracted much attention. However, due to the challenges of high development investments, high operating costs, platform safety factors, and high economic cumulative yield, the offshore heavy oil reserves of nearly 700 million tons have not been effectively utilized. In this paper, Chinese offshore heavy oil reserves were taken as the research object. The indoor one-dimensional experiments were carried out to optimize an applicable development method, and the superheated steam huff and puff was selected as the injection medium for high-speed and high-efficiency development of offshore heavy oil, which verified the great potential of the application of superheated steam in offshore heavy oil thermal recovery. A numerical simulation model for offshore heavy oil superheated steam injection development was established, and a dynamic model considering the thermal cracking of heavy oil was established through historical matching. Through the field numerical simulation models, the whole process development mode of a single sand body, thin interbedded reservoir superheated steam huff and puff turning to superheated steam flooding, and thick layer super heavy oil reservoir with bottom water sidetracking after superheated steam huff and puff for eight cycles was established. Through the numerical simulation method and grey correlation method, the main control factors of superheated steam development of different types of heavy oil reservoirs were determined, and the cumulative oil production charts of different types of reservoirs under the influence of the main control factors were built. The economic evaluation model of superheated steam development of offshore heavy oil was established. Combining multi-specialty of geological, reservoir engineering, drilling and completion, oceanographic engineering, economics, the economic limits of steam injection development under different reserve scales, and engineering conditions of offshore heavy oilfields were clarified. At last, we planned the economic production mode of undeveloped reserves and predicted the construction profile of superheated steam capacity of offshore heavy oil using the production charts and the economic charts. The research results clarify the great potential of thermal recovery development of offshore heavy oil, provide an important basis for the economic development of offshore heavy oil undeveloped reserves, and also provide an important decision for the sustainable and stable production of global heavy oil reservoirs.

Study on Hydrothermal Cracking of Heavy Oil under the Coexisting Conditions of Supercritical Water and Non-condensate Gas.

This study looked at the effects of temperature, water-oil ratio, and the addition of non-condensable gas on the thermal cracking of extra-heavy oil in the lab. The goal was to learn more about the properties and reaction rates of deep extra-heavy oil under supercritical water conditions, which are not well understood. The changes in the composition of the extra-heavy oil were analyzed with and without the presence of non-condensable gas. The reaction kinetics of the thermal cracking of extra-heavy oil were quantitatively characterized and compared between the two conditions of supercritical water alone and supercritical water mixed with non-condensable gas. The results showed that (1) under supercritical water conditions, the extra-heavy oil underwent significant thermal cracking, which led to a significant increase in the amount of light components, the release of CH4, and the formation of a new component, coke, which led to a noticeable decrease in the viscosity of the oil; (2) increasing the water-oil ratio could promote the thermal cracking of extra-heavy oil and led to a significant decrease in oil viscosity, indicating a more complete thermal cracking reaction. Moreover, increasing the water-oil ratio was found to facilitate the flowability of the cracked oil; (3) the addition of non-condensable gas intensified the conversion of coke but inhibited and slowed down the thermal cracking of asphaltene, which is detrimental to the thermal cracking of extra-heavy oil; and (4) the kinetic analysis showed that the addition of non-condensable gas resulted in a decrease in the thermal cracking rate of asphaltene, which is detrimental to the thermal cracking of heavy oil.

Catalytic cracking of heavy atmospheric gas oil to light olefins over ZSM-5 zeolite: Effect of crystal size in the absence/presence of steam

The catalytic cracking of heavy atmospheric gas oil (AGO) has been investigated to study the effect of ZSM-5 zeolite crystal size on the selectivity to light olefin in the absence and presence of steam. Dodecane (used as model compound) and heavy AGO feed streams were utilized to study the influence of changing pore shape selectivity when comparing cracking performance by nano and micro ZSM-5 zeolites. The zeolites were characterized using BET, XRD NMR, NH3-TPD and Py-FTIR. In the presence of steam, the short pores length nano ZSM-5 crystals showed enhanced catalytic cracking activity and selectivity to light olefins. The nano ZSM-5 catalyst promoted higher selectivity to light olefins through β-scission while reducing the extent of hydrogenation reactions towards the formation of liquefied petroleum gas components (LPG). In contrast, the long pores length of micro ZSM-5 tended to favor the production of more naphtha, kerosene and LPG through hydrogen transfer routes, resulting in lower selectivity to light olefins. The resulting propylene/ethylene (P/E) ratios were altered by the type of feed used, cracking reaction temperature, influence of steam and catalyst crystal size. Specifically, higher P/E ratio was achieved over nano ZSM-5 zeolite, especially with the cracking of heavy AGO feed in the presence of steam, due to an increase of monomolecular reactions through β-scission cracking mechanism.

Cracking of Heavy Oil in Supercritical Water in the Presence of Iron Oxide Nanopowder: Asphaltene Transformations and Process Kinetics

Cracking of Heavy Oil in Supercritical Water in the Presence of Iron Oxide Nanopowder: Asphaltene Transformations and Process Kinetics

Research and Development Trend of Viscosity Reduction by Catalytic Coupling Reaction of Crude Oil

In view of the increasing consumption of fossil energy, heavy oil with large reserves and wide distribution, as an important unconventional oil and gas resource, has attracted more and more attention in its exploration and development. However, due to the high content of heavy components in heavy oil, its viscosity is high, its fluidity is low, and its quality is poor. Therefore, the key to enhance heavy oil recovery is to reduce its viscosity, improve its fluidity and improve its quality. At present, steam huff and puff, steam flooding and in-situ upgrading and viscosity reduction of heavy oil are the conventional methods for heavy oil recovery. Considering the production cost, the hydrothermal catalytic cracking technology for heavy oil recovery is studied. However, most of these researches only focus on the preparation and application of catalytic viscosity reducer, and there is still a lack of in-depth and systematic research on its specific viscosity reduction mechanism. Therefore, on the basis of abundant active hydrogen provided by alcohol water reforming reaction, it is of great theoretical value and practical significance to design the application of high-efficiency heavy oil viscosity reduction catalyst by using the super molecular interaction of in-situ active minerals and exogenous metal complexes to catalyze the high-efficiency hydrothermal cracking of heavy oil.

Transformation of Heavy Oil Components in the Process of Initiated Cracking

In this work, the effect of butyl bromide on the thermal transformations of heavy oil from the Karmalskoye field (Republic of Tatarstan) in the presence of an initiating additive, n-butyl bromide, was studied. It was shown that the addition of butyl bromide increased the yield of gasoline and diesel fractions due to the destruction of high-molecular-weight components. It was established that almost all bromine from butyl bromide entered the compaction products upon the cracking of heavy oil, and butyl radicals entered the composition of gaseous products. It was noted that the direction of thermal transformations of hydrocarbons changed in the presence of butyl bromide. As compared to the initial oil, the amount of low-molecular-weight alkanes and isoprenoids increased significantly, the concentration of cyclohexanes and cyclopentanes decreased, and tri-, tetra- and pentacyclic saturated hydrocarbons were completely destroyed.

Preparation of the Al13 Sol via Electrodialysis as an Effective Binder of FCC Catalysts

This study presented a clean preparation process of alumina sols via electrodialysis. For the first time, as an effective binder for fluid catalytic cracking catalysts, the Al13-enriched product was found to be easily converted to γ-Al2O3 with a larger BET specific surface area, pore volume, more Lewis acids, Al-OH sites, and lower Cl– content after calcination. A series of spray-dried FCC catalysts were steam-aged and tested by heavy oil cracking. In comparison with the commercial sol-containing FCC catalysts, Al13-containing catalysts exhibited higher accessibility of active centers, mechanical strength, heavy oil cracking ability, and liquid yield.

One-step high-value conversion of heavy oil into H2, C2H2 and carbon nanomaterials by non-thermal plasma

Non-thermal plasma is promising for cracking the abundant but low-quality heavy oil into value-add chemicals due to its wide feedstock adaptability and high conversion rate. In this work, heavy oil cracking characteristics by microsecond pulsed spark discharge plasma were investigated in terms of pulse voltage, pulse repetition frequency and discharge power. Experiment results indicate pulse voltage and pulse repetition frequency are the main factors to control product yields and distribution. Pulse voltage determines single pulse energy and influences discharge stability and gas temperature. Pulse repetition frequency determines discharge intervals and affects collision reactions and quenching process. The maximum heavy oil conversion rate was 50.4% and the mass yields of H2 and C2H2 were 3.3% and 19.7% with 10.1 W discharge power, and H2 and C2H2 production energy consumption were 25.2 kW·h/m3H2 and 55.4 kW·h/m3C2H2. Compared with thermal plasma, heavy oil conversion rate of this work increased 12% with above 95% reduction in discharge power, and this work has a significant advantage in H2 and C2H2 production energy consumption. Carbon nanomaterials composed of carbon nanoflakes and nanoparticles can be obtained while producing H2 and C2H2. Especially, there were few-layers graphene nanoflakes (GNFs) in the carbon nanomaterials, which realized the full utilization of heavy oil. The possible reaction mechanism of heavy oil cracking was discussed using saturates-nucleating-aromatics-flaking theory. This work provides an effective COx-free method for one-step production of H2, C2H2 and carbon nanomaterials, which has wide application prospects for heavy oil utilization.

Hydrocracking of n-hexadecane via liquid or gaseous water assisted pulsed spark discharge in liquid

In view of the problem that it is difficult to ignite discharge in the insulating liquid medium, the method of water assisted where the spark will occur was proposed. The introduction of water in any form lead to easier breakdown in the insulating liquid medium, and can also avoid carbon deposition caused by spark discharge, so as to achieve the purpose of reducing the discharge voltage. This paper also analyzes the liquid products after discharge, and it is found that the higher heating value of the liquid products was influenced by water state and peak voltage, which increased by 2.25% under the action of spark discharge. In addition, extending processing time may not be a good way to increase higher heating value of liquid products. This method not only solves the difficult problem of plasma generation in liquid medium, but also provides evidence for plasma-chemical reactions in heavy oil cracking and hydrogenation.

Synthesis of Micromesoporous Zeolite-Alumina Catalysts for Olefin Production from Heavy Crude Oil

Maximizing the production of high-value olefins from heavy crude oil is a crucial topic in the downstream refining industry. However, converting heavier fractions is a major challenge due to the small pore size of the zeolites. Therefore, this work aimed to develop extrudate zeolite catalysts posing adequate micromesoporous pore network and moderate acidity by combining microporous zeolite with the boehmite phase of alumina. These extruded zeolite-alumina catalysts are expected to allow sufficient diffusion of heavy fractions, thus leading to high cracking of heavy oil into valuable olefins. Different zeolite-alumina catalysts of varying alumina content ranging from 25 to 75% (AlZ-25, AlZ-50, and AlZ-75) were prepared in the laboratory to study the optimum zeolite-alumina ratios for maximum olefin production from heavy oil. The catalysts were characterized for their chemical and physical properties using nitrogen adsorption (N2 adsorption), X-ray diffraction (XRD), inductively coupled plasma (ICP) spectrometry, Fourier transform infrared (FT-IR) spectroscopy, and NH3 temperature programmed desorption (TPD). A gradual increase in the average pore diameter (APD) of the catalysts was observed due to the alumina ratio with a distinct range of acidity that is in the range of 125 to 375°C, and also the geometry of pores is not the same for all of the supports. Catalytic performance tests were conducted in a fixed-bed reactor at 450°C, 10 bar, and liquid hourly space velocity (LHSV) of 1 h−1. The results revealed that the prepared catalysts were thermally stable and effective in heavy oil conversion to olefins. Moreover, the selectivity of propylene was higher than that of ethylene (P/E) due to the modified textural and acidic properties of the catalysts. The results showed that the catalysts prepared with moderate acidity and adequate mesopores exhibited a considerable effect on the conversion of heavy crude oil into olefins. Hence, the acidity and mesoporosity of the catalysts play a vital role in determining the catalyst performance.