Catalytic Cracking Of Heavy Oil Research Articles

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.

Study on the Regeneration of Waste FCC Catalyst by Boron Modification.

Regeneration has been considered as an ideal way for the post-treatment of waste FCC catalyst (ECat). In this work, the degeneration mechanism of ECat was firstly researched and attributed to the increasing of strong acid sites accessibility of ECat in contrast with fresh FCC catalyst by adsorption FTIR. Based on the proposed degeneration mechanism, ECat was successfully regenerated through suitable weakening for strong acid sites by boron modification. Characterization and evaluation results suggested that, the strong acid sites of regenerated ECat (R-ECat) were apparently decreased by boron modification which had significantly improve the heavy oil catalytic cracking performance of R-ECat. Because of the excellent performance, R-ECat in this work could successfully substitute for partial fresh FCC catalyst in FCC unit, which would provide a practicable way for the reutilization of ECat.

Enhanced micro-explosion to improve the yield of light oil in catalytic cracking of water-in-heavy oil emulsion prepared by continuous membrane emulsification

Membrane emulsification provides new ideas for improving the atomization performance of high viscosity heavy oil in catalytic cracking process, thereby improving the distribution of catalytic cracking products. A comprehensive understanding of the micro-explosion characteristics and catalytic cracking of low water content heavy oil emulsion is the key to the application of membrane emulsification technology in heavy oil catalytic cracking process. Therefore, different water droplet sizes and water content of heavy oil emulsion were controllably prepared by continuous membrane emulsification, and their micro-explosion characteristics and catalytic cracking performance were investigated. The evaporation of heavy oil emulsion droplets (water content over 3 vol%) only underwent the heat transfer stage and the fluctuating evaporation stage due to the strong micro-explosion. The micro-explosion delay time of emulsion droplets decreased from 2.631 to 0.434 s/mm2 with increased temperature (300–600 ℃), increased from 0.645 to 1.042 s/mm2 with increased water content (1–5 vol%), and increased from 0.642 to 1.237 s/mm2 with increased average droplet size (1.80–14.6 μm). The child droplets generated after micro-explosion were characterized, and the different heating behaviors were quantitatively distinguished by the average size of the child droplets. Additionally, the micro-explosion performance (i.e. child droplets size and strong micro-explosion probability) of emulsion droplets improved with increasing water content and average water droplet size, while it initially decreased and then increased when the temperature increased. Furthermore, the improvement of micro-explosion performance by membrane emulsification can increase the yield of light oil (up to a maximum increase of 10.82 %) and reduce the yield of coke (up to a maximum decrease of 5.99 %) in the heavy oil emulsion catalytic cracking.

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.

GC-MS analysis of hydrocarbons formed after catalytic cracking of heavy oil

The heavy oil from the Mordovo–Karmalskoye oil field is cracked in the presence of silica-alumina Al-Si catalyst and Al-Si catalyst modified with NiCrWC. The composition of saturated and aromatic compounds before and after catalytic cracking is studied. It is shown that in the presence of a modified NiCrWC/Al-Si catalyst, the destruction reactions resin-asphaltene components proceed more intensively than during cracking in the presence of Al-Si. Transformations of hydrocarbons during cracking of heavy oil in the presence of NiCrWC/Al-Si catalyst are more intensive as evidenced by the predominance of low-molecular homologues of normal and iso-structure alkanes over high-molecular ones and increased contents of C7–C10 alkylbenzenes, unsubstituted naphthalene, and methylnaphthalenes. This catalyst contributes to the complete decomposition of high-molecular cyclanes, mono- and trinaphthenoarenes. It has been shown that NiCrWC/Al-Si catalyst the formation of a larger amount of low-molecular-weight n-alkanes compared to high-molecular ones.

The Research on Anti-Nickel Contamination Mechanism and Performance for Boron-Modified FCC Catalyst.

Fluid catalytic cracking (FCC) is still a key process in the modern refining area, in which nickel-contamination for an FCC catalyst could obviously increase the dry gas and coke yields and thus seriously affect the stability of the FCC unit. From the points of surface acidity modification and Ni-passivation, in this paper, a boron-modified FCC catalyst (BM-Cat) was prepared using the in situ addition method with B2O3 as a boron source and emphatically investigated its mechanism and performance of anti-nickel contamination. The mechanism research results suggested that, in calcination, boron could destroy the structure of the Y zeolite and thus decrease the total acid sites and strong acid sites of the Y zeolite from 291.5 and 44.6 μmol·g−1 to 244.2 and 32.1 μmol·g−1, respectively, which could obviously improve the dry gas and coke selectivity of the catalyst and thus enhance the nickel capacity for BM-Cat; on the other hand, under hydrothermal conditions, boron could react with NiO and form into NiB2O4, which could obviously raise the range of the reduction temperature for NiO from 350–600 °C to 650–800 °C and thus promote the nickel-passivation ability for BM-Cat. Therefore, evaluation results of heavy oil catalytic cracking indicated that, under the same nickel-contamination condition, in contrast to the compared catalyst (C-Cat), the dry gas yield, coke yield, and H2/CH4 of BM-Cat obviously decreased by 0.77 percentage points, 2.09 percentage points, and 13.53%, respectively, with light yield and total liquid yield increasing by 3.25 and 2.08 percentage points, respectively, which fully demonstrates the excellent anti-nickel contamination performance of BM-Cat.

Titanium-Doped Mesoporous Silica with High Hydrothermal Stability for Catalytic Cracking Performance of Heavy Oil

With the increasing attention to light oil, the catalytic cracking process of heavy oil is being vigorously developed. The silicon hydroxyl groups on the surface of mesoporous silica materials can be used as weak acid centers to preliminarily crack heavy oil macromolecules. Herein, a strategy of introducing titanium into a silica skeleton for modification is proposed to increase active sites, as well as improve the hydrothermal stability. After titanium modification, the mesoporous silica material has more weak acid sites, and shows better ability in deep cracking heavy oil. Notably, when the content of titanium doping is 2%, the CT(2) catalyst exhibited the best high-temperature hydrothermal stability, which can be used as a suitable heavy oil catalytic cracking catalyst. This kind of titanium-modified mesoporous silica material shows great application prospects in heavy oil catalytic cracking, which may provide a novel idea for subsequent development.

Catalytic upgrading of heavy oil from the Ashalchinskoye oilfield

The work deals with study the effect of the NiCrWC catalyst on the composition of the products of catalytic cracking of heavy oil at a temperature of 450 °C for 100 minutes is established. The relevance of research aimed at studying the catalytic activity in the processing of heavy oil. It has been installed that the addition of NiCr-WC promotes the retardation of coke and asphaltenes formation and an increase in the destruction of high-molecular components of heavy oil. The use of a catalyst makes it possible to increase the yield of gasoline and diesel fractions by 35.8 wt % compared to the initial oil. Due to the formation of gaseous products, the removal of 2 wt % of sulfur from oil is observed. The data of X-ray phase analysis and scanning electron microscopy show that metal oxides are sulfidized on the surface of nichrome particles to form sulfides of these metals. It was found that NixSy and CrxSy formed on the catalyst surface contribute to an increase in the degradation of oil resins and asphaltenes.

Effect of pre-oxidation of dispersed catalysts on heavy oil cracking

Heavy and extra-heavy oils are characterized by a high content of resins, asphaltenes, and sulfur, which hinders oil refining. The purpose of this paper is to study the effect of NiCrWC catalyst surface pre-oxidation on the composition of products of heavy oil catalytic cracking. The optimal conditions for the pre-oxidation of the catalyst are a temperature of 450 °C and a duration of 2 hours in air. The products of catalytic cracking are analyzed by content of saturated and aromatic hydrocarbons, resins and asphaltenes, gas chromatography, X-ray diffraction, and scanning electron microscope spectrometry methods. Pre-oxidation of a NiCrWC catalyst at 450 °C leads to a decrease in the content of macromolecular components, sulfur, by-products, and an increase in the yield of a fraction with a boiling point up to 360 °C. The decrease in sulfur content in the course of heavy oil upgrading is caused both by the interaction of metal oxides on the surface of NiCrWC with S-containing compounds of the feedstock, and by the removal of sulfur in the form of gas. A hypothetical mechanism for the cracking of heavy oil components over pre-oxidized catalysts is proposed.

Synthesis of Si-Modified Pseudo-Boehmite@kaolin Composite and Its Application as a Novel Matrix Material for FCC Catalyst

Fluid catalytic cracking (FCC) has been the primary processing technology for heavy oil. Due to the inferior properties of heavy oil, an excellent performance is demanded of FCC catalysts. In this work, based on the acid extracting method, Si-modified pseudo-boehmite units (Si-PB) are constructed in situ and introduced into the structure of kaolin to synthesize a Si-PB@kaolin composite. The synthesized Si-PB@kaolin is further characterized and used as a matrix material for the FCC catalyst. The results indicate that, compared with a conventional kaolin matrix, a Si-PB@kaolin composite could significantly improve the heavy oil catalytic cracking performance of the prepared FCC catalyst because of its excellent properties, such as a larger surface area, a higher pore volume, and a good surface acidity. For the fresh FCC catalysts, compared with the FCC catalysts using conventional kaolin (Cat-1), the gasoline yield and total liquid yield of the catalyst containing Si-PB@kaolin (Cat-2) could obviously increase by 2.06% and 1.55%, respectively, with the bottom yield decreasing by 2.64%. After vanadium and nickel contamination, compared with Cat-1, the gasoline yield and total liquid yield of Cat-2 could increase by 1.97% and 1.24%, respectively, with the bottom yield decreasing by 1.80 percentage points.

Simulation Study on the Effect of Flue Gas on Flow Field and Rotor Stress in Gas Turbines

A flue gas turbine is the main energy recovery equipment in a heavy oil catalytic cracking unit. Blade erosion and fracture are the main reasons for gas turbine failure. In this study, the characteristics of the flow field and rotor stress in the gas turbine under different fume volumes are simulated and analyzed by simulation software (ANSYS). The influences of fume volume on the high-temperature fume flow field, temperature, velocity, catalyst particle movement rotor stress in the gas turbine, as well as the influence law of flue gas flow on temperature gradient, pressure gradient, velocity distribution, and the main position of blade erosion were studied. The stress distribution and maximum stress position of the impeller were also determined. It was found that the variation trends of the pressure gradient in the calculation domain of the gas turbine under different fume volumes are similar. The pressure on the working face of the rotor blade decreases gradually along the flow direction of the high-temperature fume. The highest pressure appears near the sharp corner with the large radius of the front edge of the rotor blade. The variation of the fume flow rate has little influence on the temperature field of the entire machine. The erosion wear of the rotor blade mainly occurs in the leading edge and tail. The maximum stress point of the blade is located at the large fillet of the first pair of tenon teeth. The maximum stress point of the disc is located at the large fillet of the third pair of tenon teeth. It is believed that these research results have reference help for analyzing the typical failure causes of flue gas turbine, optimizing the actual operating conditions and the reconstruction design of flue gas turbine.

NiO based catalysts obtained “in-situ” for heavy crude oil upgrading: effect of NiO precursor on the catalytic cracking products composition

Heavy and super-heavy oils are characterized by a high content of resins and asphaltenes, which complicate the transportation and refining of oil and lead to an increase in the cost of refinery products. Currently, of particular interest are catalysts that are formed directly under the conditions of the process from precursors, which are various salts. In this work influence of NiO precursor on the heavy oil catalytic cracking products composition. The upgrading in all experiments was carried out at a temperature 450 °C for 80 min. The optimal catalyst content calculated to the NiO in experiments 2 and 3 was 0.5 wt. % of the feedstock weight. The ratio salt:ethanol in experiment 3 was 1:1 wt. The products of catalytic cracking were analyzed by SARA, GC, XRD and FT-IR spectrometry. The dissolution of Ni(NO3)2•6H2O in ethanol results in a decrease in the content of high molecular weight components and an increase in the yield of the fraction boiling up to 360 °C. A decrease of sulfur content in the course of heavy oil cracking is caused by both interactions of NiO formed over cracking with S-containing compounds of feedstock leading to formation of Ni9S8 and Ni0.96S and sulfur removal in form of gas.

General synchroextracting chirplet transform: Application to the rotor rub-impact fault diagnosis

The rub-impact fault between the rotor and the stator surface is a common and serious failure in rotating machinery. The vibration signals acquired during the rotating machinery operation will carry the time-varying characteristics of rapid fluctuating instantaneous frequency (IF) when the healthy condition of rotor system changes. The proposed method is termed as the general synchroextracting chirplet transform which is based on the classical chirplet transform and employs the second-order synchroextracting transform to concentrate the time-frequency representation (TFR). Moreover, an adaptive demodulation parameters determination method based on kurtosis is proposed. The proposed method is non-sensitivity to noise, allows for signal reconstruction, and retains certain processing ability for multicomponent signals. The effectiveness and practical value of the method are verified by the numerical signals and the vibration signals of the heavy oil catalytic cracking machine which has the rotor rub-impact fault.

A new composite consisting of Y zeolite and ZrO2 for fluid catalytic cracking reaction

In fluid catalytic cracking (FCC) unit, basic nitrogen species in heavy oil result in the poison of Y zeolite acid sites and the loss of heavy oil conversion. To solve this issue, Y/ZrO2 composites are prepared by a two-stage crystallization method. The composite bears a uniform particle size and micro-mesoporous hierarchical structure. The Zr–O–Si chemical bonds are observed between Y zeolite and ZrO2 in Y/ZrO2 composites, which result from the incorporation of Zr species into the framework of Y zeolite. Compared to the mechanical mixture of Y zeolite and ZrO2, composites have abundant Lewis acid sites, which capture basic nitrogen species to protect the acid sites over Y zeolite. It endows a higher heavy oil conversion (increased by 2 wt%) to the Y/ZrO2 composites in the catalytic cracking of heavy oil with high-basic nitrogen compounds. It is worth noting that the hierarchical pore structure of Y/ZrO2 composite inhibits coke deposition. These results are important to propose a new FCC catalyst to catalytic crack heavy oil with high amount of bulky basic nitrogen compounds.

Research on equipment fault prediction expert system based on big data dimension reduction

Due to the complex structure and massive volume of large equipment in petrochemical enterprises, it was very difficult to carry out inspection and maintenance work. The traditional expert system used a single knowledge base and reasoning machine, so the processing efficiency and prediction accuracy were low. In this paper, the dimensionality reduction which is used to process a large amount of physical information collected by the sensors, remove redundant components and extract main characteristic parameters. Meanwhile, combined with the powerful pattern recognition and judgment ability of fuzzy neural network, the forward reasoning mechanism and error back propagation keeping continuous training correction until meeting the accuracy requirements, the expert system gave the equipment fault prediction conclusion. Finally, taking main fan oil station circulating oil pump and motor of heavy oil catalytic cracking unit and nine stages of bearing damage as monitoring objects, the fault predictions was implemented by the following steps: data collection, feature extraction, dimension reduction of big data and expert system with the fusion of fuzzy neural network, and it is proved that the expert system with fuzzy neural network based on dimension reduction can greatly improve the convergence speed.

Catalytic upgrading of heavy oil over mesoporous HZSM-5 zeolite in the presence of atmospheric oxygen flow

Alkaline treated ZSM-5 zeolite was used in heavy oil upgrading process under atmospheric oxygen flow. Alkaline treatment was employed to induce mesopores in ZSM-5 catalyst structure to alleviate the mass transfer and reduce diffusion limitations. XRD, BET and XRF analyses were employed to investigate the effect of alkaline treatment. Effect of oxygen atmospheric flow, supplied by air stream, on heavy oil catalytic cracking process was investigated in a fixed bed reactor. Obtained liquids were analyzed by FTIR and GC/SIMDIS. Results revealed that percent of light oil (naphtha + kerosene) produced was nearly doubled in the presence of 5 wt% oxygen in the feed. Conversion of heavy oil (content with the BPT higher than 370 °C) was enhanced from 45.7% up to 58.1% by applying air stream. Viscosity reduction was elevated from 40% in nitrogen atmosphere to 53% in presence of 5 wt% oxygen content. Spent catalysts were characterized by TGA, XRD and BET analyses in order to determine coke deposition and catalyst structural stability. Oxidative cracking increased the amount of coke production over the catalyst, however, structural stability of the catalyst was not altered compared to conventional cracking process and crystalline structure of the catalyst was preserved after 5 h time on stream.

Catalytic Cracking of Heavy Oil from Waste Plastic in Tapered Circulating Fluidized Bed Riser Reactor

Because of the continuous increase in the amount of plastic waste, catalytic cracking is an interesting method that could be used to convert heavy oil from thermal cracking of plastic waste into fuel. The objective of this study was to investigate the hydrodynamic behavior and the performance of catalytic cracking of heavy oil in a circulating fluidized bed reactor using computational fluid dynamics. The two– fluid model incorporated with the kinetic theory of granular flow was applied to predict the hydrodynamic behavior with a reactive flow. Three reactor geometries were studied, which included a conventional riser, tapered–out riser, and tapered–in riser. The four–lump kinetic model was used to describe the catalytic cracking of heavy oil from waste plastic. A core–annulus flow pattern was found in the three reactor geometries. The solid fraction distribution of the tapered reactor was found to be more uniform than that of the conventional riser. The tapered–in riser showed the highest heavy oil conversion with the lowest gasoline selectivity. However, the heavy oil conversion and gasoline selectivity of the conventional and tapered–out reactors were not significantly different.

Scaling of a catalytic cracking fluidized bed downer reactor based on computational fluid dynamics simulations.

Circulating fluidized bed downer reactors (downer reactors) exhibit good heat and mass transfer, and the flow behavior approaches the ideal plug flow. This reactor is superior for catalytic cracking reactions in which the intermediate is the desired product. However, the hydrodynamic behavior and reactor performance have mostly been investigated in small-scale or laboratory-scale reactors. The objective of this study was to investigate the up-scaling of the catalytic cracking of heavy oil in three downer reactors with heights of 5, 15, and 30 m, using computational fluid dynamics simulations. A two-fluid model with the kinetic theory of granular flow was used to predict the hydrodynamics and performance of the chemical reactions. The kinetics of catalytic cracking of heavy oil were described by a 4-lump kinetic model. The chemical performance similarity was identified by using radial and axial distributions of heavy oil conversion, gasoline mass fraction, and gasoline selectivity. The chemical performance similarity cannot be achieved by using the hydrodynamic similarity parameter . A modified up-scaling parameter was proposed, . The chemical performance similarity of identical catalytic cracking downer reactors can be achieved with deviation in the range of ±10% and mean relative absolute error of less than 5%.

Improving the physicochemical properties of Y zeolite for catalytic cracking of heavy oil via sequential steam-alkali-acid treatments

Abstract In this study, modified Y zeolite with high catalytic activity and long lifetime was successfully prepared using sequential steam-alkali-acid treatments. Different alkali agents (NaOH, Na2CO3 and CaCO3) with various concentrations were used in order to improve the catalytic performance of the synthesized Y zeolite in heavy oil conversion process. The physicochemical properties of the prepared samples were investigated using XRD, FESEM, EDX, solid-state29Si and 27Al NMR, BET, XRF, ICP, FTIR, and NH3-TPD techniques. In addition, the properties of the deposited coke on the used catalysts were studied by FTIR and TGA-DTA techniques. Al extraction via steam treatment created Si-rich regions in the Y zeolite samples. Then, the Si elements were easily extracted from these Si-rich regions by using alkali treatment. In addition, acid washing with weak EDTA solution resulted in removal of extracted elements from the zeolite structure and pore opening after steam and alkali treatments. Combination of these treatments stimulated mesopores formation and improvement in textural properties for the Y zeolite samples. Structural and textural properties of Y zeolite were found to be preserved after sequential treatments. Catalytic performance of the prepared catalysts was investigated for the heavy oil catalytic cracking process in a fixed bed reactor. Regardless of the type of alkali agent used for sequential treatments, the heavy oil conversion and gasoline selectivity were strongly improved for all the modified catalysts in reference to the parent catalyst. The catalytic activity tests showed that sample treated with 1 M CaCO3 solution could secure a high heavy oil conversion (70%) and high selectivity towards gasoline and kerosene (45%). Furthermore, modification with CaCO3 inhibits coke formation significantly and enhanced the catalytic lifetime.

Effect of Retarding Components on Heavy Oil Catalytic Cracking and Their Corresponding Countermeasures

Heavy oil could be classified into two parts: one is the easy cracking part, which is the main source of liquid hydrocarbon transportation fuels and industrial chemicals, and the other is the refractory cracking part, which is failed to be cracked by the present technologies and has negative effects on upgrading. Therefore, the efficient method to obtain a higher conversion of heavy oil is needed for the heavy oil processing industry. Coker gas oil (CGO), used as an example of heavy oil, is supposed to be hard to process during fluid catalytic cracking (FCC). The structural information in the molecular level of basic nitrogen compounds, nonbasic nitrogen compounds, and condensed aromatics in feedstock and liquid products from FCC was investigated. The coked catalysts in the catalytic cracking reaction of CGO were characterized. The results showed that these compounds, especially basic ones, are more difficult to crack, which are preferentially chemisorbed on the surface of the catalyst leading to less acid sites for other easy cracking hydrocarbons and the decrease of the activity of catalysts. Physical solvent removal and chemical catalytic adsorption were used to pretreat heavy oil, and the result indicated that either physical solvent removal or chemical catalytic adsorption is a good way to avoid the retarding effects of refractory cracking components, and better product distributions can be obtained.