Residue Fluid Catalytic Cracking Research Articles

Hydrogenation and TMP Coupling Process: Novel Process Design, Techno-Economic Analysis, Environmental Assessment and Thermo-Economic Optimization

The production of high-quality gasoline and light olefins harbors tremendous industrial and economic significance. In this paper, a novel process is proposed for converting inferior light cycle oil (LCO) into propylene and ethylene, as well as the high-octane-number gasoline with rich BTX contents. The unique feature for the novel process is the integration of LCO selective hydrogenation unit with two-stage riser catalytic cracking. For comparative techno-economic and environmental analyses, typical two-stage riser catalytic cracking for maximizing the propylene (TMP) process and conventional residue fluid catalytic cracking (RFCC) process models are developed. Based on the detailed process modeling and simulation results, techno-economic evaluation and environmental assessment have been performed. It is found that the novel process, coupled hydrogenation and TMP process, has a favorable impact on both the economic and environmental performances. The HTMP process has the highest net present value that means 2.13 times of TMP and 4.94 times of RFCC process, and reduces 15.26 t CO2 equivalents per million dollars output value compared with the TMP process. Moreover, we conduct the thermo-economic optimization for the HTMP process based on the exergy analysis. The result shows that full scale hydrogenation and recycling of hydro-LCO and increasing of the second riser outlet temperature could significantly increase the profitability of this novel process.

Preparation of nanozeolite-based RFCC catalysts and evaluation of their catalytic performance in RFCC process

Abstract The NaY zeolites with different particle sizes of about 20–30 nm and 1–2 µm were synthesized by hydrothermal routes and characterized by XRD, FT-IR, BET and SEM techniques. The XRD analyses demonstrated the formation of NaY zeolites with high crystallinity and the BET analyses showed that the nanozeolite possessed a higher external surface area (102 m2/g) than microzeolite (11 m2/g). In order to evaluate the effect of zeolite particle size and zeolite content on the catalytic performance of the residue fluid catalytic cracking (RFCC) catalyst, nanozeolite-based and microzeolite-based catalysts were prepared using silica as inactive matrix. It is clearly demonstrated that the acidity improves with the reduction of zeolite particle size. On the other hand, in equal zeolite content (30 wt%), the nanozeolite-based catalyst possessed higher acidity (2.30 mmol NH3/g catalyst) than microzeolite-based catalyst (1.53 mmol NH3/g catalyst). The microactivity tests (MAT) demonstrated that in equal zeolite content the nanozeolite-based catalysts showed higher catalytic performance than microzeolite-based catalysts. Moreover, the nanozeolite-based catalyst with 30 wt% zeolite (NC30) and a BET area of 346 m2/g showed the optimum catalytic performance in RFCC process, with the highest gasoline yield (32 wt%) and gasoline selectivity (56 wt%).

Development of heavy oil upgrading technologies in China

Abstract Heavy oils have high viscosity, density, and Conradson carbon residue and high contents of sulfur, nitrogen, oxygen, nickel, and vanadium, as well as asphaltenes, which can cause problems for producers, leading to catalyst deactivation and fouling and plugging of tubing, pipes, valves, and reactor flow lines. Heavy oil upgrading can be classified into carbon rejection and hydrogen addition processes, mainly including four technologies: (1) the fluid catalytic cracking (FCC) process, which catalytically converts heavy oil into light fractions, like liquid petroleum gas, naphtha, and light cycle oil; (2) the hydro-processing process, which catalytically converts heavy oil to high-quality feedstock for FCC and hydrocracking processes under the hydrogen atmosphere without coke formation; (3) the coking process, which thermally converts heavy oil into light liquid fractions and large amounts of coke; and (4) the solvent deasphalting process, which fractionates distillation resid to provide feedstock for residue FCC, such as the residue oil solvent extraction. This paper reviews the progress on basic research of heavy oil chemistry and processing technology developments in China. Heavy oils were comprehensively characterized by the supercritical fluid extraction and fractionation technology and high-resolution mass spectrometry. The FCC process for maximizing iso-paraffin, new residue hydroprocessing technologies, progress in coking process, and a new process – the Supercritical Fluid Selective Extraction Asphaltene Technology – were discussed. As an emerging and promising research area, molecular management techniques were prospected, as well as a new concept of coupling the SELEX-Asp with the conventional heavy oil upgrading processes.

Sulfate resistance of RFCC spent catalyst-blended Portland cement

The reuse of spent catalysts from residue fluid catalytic cracking (RFCC) units as pozzolanic materials in cement and concrete production offers a number of important benefits. In spite of all these benefits, the durability performance of the produced blended cement is an important issue to be considered. This study investigates the effects of RFCC spent catalyst on durability performance of hardened Portland cement paste in a highly aggressive sulfate environment. The 28-day cured paste specimens prepared from binary cement mixtures incorporating different replacement levels of 0, 10, 20, and 30% (by mass) RFCC spent catalyst at a constant water-to-cement ratio of 0.30 were exposed to 10 mass% solution of magnesium sulfate. The accelerated sulfate attack under alternative cycles of wetting and drying was studied by monitoring the changes in compressive strength, length, and mass of specimens and also by the application of XRD, SEM and EDX techniques. Based on the results and a comparison with plain Portland cement, binary cement mixtures exhibit a higher rate of deterioration in spite of their significantly improved compressive strengths resulted from pozzolanic reaction.

Modelling and simulation of an industrial RFCCU-riser reactor for catalytic cracking of vacuum residue

A one-dimensional adiabatic mathematical model was developed for the riser reactor of an industrial residue fluid catalytic cracking unit (RFCCU). A seven-lump kinetic model was presented for the catalytic cracking of vacuum residue, taking cognisance of diffusion resistance, which is a departure from the general norm in the literature. Also, heat transfer resistance between the fluid and solid phases was incorporated into the energy balances for instantaneous and one-dimensional vaporization of feedstock. The developed model was a set of twelve coupled, highly non-linear and stiff ordinary differential equations, ODEs, which was numerically solved with an implicit MATLAB built-in solver, ode23t, designed deliberately for handling stiff differential equations to circumvent the problem of instability associated with explicit methods. An excellent agreement was achieved between the industrial RFCCU plant data and the simulated results of this study, with average absolute deviation being < ± 5% for instantaneous vaporization of feedstock in all cases investigated. Moreover, the simulated results revealed that half of the reactor was relatively redundant as this accounted for only 3% of the conversion. Hence, the findings of this study could be useful to the production practice for the Khartoum Refinery Company.

Optimal Design of Petroleum Refinery Configuration Using a Model-Based Mixed-Integer Programming Approach with Practical Approximation

We present a model-based optimization approach to determine the configuration of a petroleum refinery for grassroots (new) or existing site that considers a large number of commercial technologies particularly for heavy oil processing of crude oil residue from an atmospheric distillation unit. First, we develop a superstructure representation for the refinery configuration to encompass all possible topology alternatives comprising 96 technologies and their interconnectivities. The superstructure is postulated by decomposing it to incorporate representative heavy oil processing scheme alternatives that center on the technologies for atmospheric residual hydrodesulfurization (ARDS), vacuum residual hydrodesulfurization (VRDS), and residual fluid catalytic cracking (RFCC). We formulate a mixed-integer linear program (MILP) based on the superstructure by devising logic propositions on design and structural specifications that represent these processing options to aid convergence to an optimal refinery configu...

Catalytic cracking of wax esters extracted from Euglena gracilis for hydrocarbon fuel production

Wax esters (WEs) synthesized by Euglena gracilis are potential sources for alternative fuels because of their high productivity, recent success in mass cultivation, and low energy consumption in extraction. In this study, deoxygenation of Euglena WE and conversion to hydrocarbons in a catalytic cracking process under a hydrogen-free atmosphere was investigated using a residue fluid catalytic cracking equilibrium catalyst with enhanced hydrogen-transfer activity. The deoxygenation of Euglena WE proceeded more rapidly with higher H2O selectivity than that of saturated triglycerides. This is because initial β-elimination of WEs produces saturated fatty acids and higher olefins; the higher olefins rapidly release hydrogen species during cracking, cyclization and aromatization, and the hydrogen species accelerate hydrodeoxygenation of the saturated fatty acids. Furthermore, the cracking of Euglena WE produced large amounts of paraffins and olefins instead of aromatics. Therefore, Euglena WE was confirmed to be a preferable feedstock for the catalytic cracking process for hydrocarbon fuel production.

Investigating the Influence of the Cerium loading in prepared Y zeolite from Iraqi kaolin on its Catalytic Performance

In this study, the effects of different loading doses of cerium in the prepared NaY zeolite from Iraqi kaolin were investigated. Al-Duara refinery atmospheric residue fluid catalytic cracking was selected as palpation reaction for testing the catalytic activity of cerium loading NaY zeolite. The insertion of cerium in NaY zeolites has been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with cerium and the weight percent added are 0.35, 0.64, and 1.06 respectively. The effects of cerium loading to zeolite Y in different weight percent on the cracking catalysts were studied by employing a laboratory fluidized bed reactor. The experiments have been performed with weight hourly space velocity (WHSV) range from 6 to 24 h-1, and the temperature range from 450 to 510 oC.&#x0D; The activity of the catalyst with 1.06 wt% cerium has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the cerium causes an increase in the thermal stability of the zeolite.&#x0D;

Novel Chemical Looping Combustion Assisted Residue Fluid Catalytic Cracking Process in Order To Reduce CO2 Emission and Gasoline Production Enhancement

In this novel study, application of chemical looping combustion (CLC) as the heat source for the endothermic residue fluid catalytic cracking (RFCC) process has been investigated to stabilize the RFCC riser temperature for increasing efficiency and proficiency of the process. A mathematical conceptual model has been presented to analyze the performance of RFCC process coupled with chemical looping combustion (RFCC-CLC). NiO18-α-Al2O3 particles have been employed as the oxygen carrier agents in CLC system, which have shown unprecedented reactivity and allow for working under high temperatures with complete conversion of CH4 in RFCC-CLC configuration. This structure consisting of three coaxial vertical tubular reactors and the riser reactor is surrounded by the air and fuel reactors, respectively (all three reactors operate in the fluidized regime). The most illustrious advantage of applying CLC technique is the inherent CO2 separation from flue gas. In addition, results indicate that methane conversion tends toward 1 and a 10% by weight increase in gasoline production and a 1.3% by weight reduction in coke formation have been achieved which reveals the supremacy of the RFCC-CLC configuration.

Lump kinetic study of waxy distillate catalytic cracking in microactivity tests

ABSTRACTThe catalytic cracking of waxy distillate was investigated using equilibrium residue fluid catalytic cracking catalyst in a microactivity setup. The effect of temperature on gasoline yield was studied and a four-lump kinetic model including six reaction rates was employed. The kinetic parameters were calculated based on the experimental data using the fourth-order Runge–Kutta method and Marquardt's algorithm least square error. Activation energies and frequency factors were calculated using the Arrhenius equation. The highest gasoline yield was observed in the temperatures between 520 and 540°C, while the undesired gas products increased in higher temperatures.

The Catalytic Activity of Modified Zeolite Lanthanum on the Catalytic Cracking of Al-Duara Atmospheric Distillation Residue.

Atmospheric residue fluid catalytic cracking was selected as a probe reaction to test the catalytic performance of modified NaY zeolites and prepared NaY zeolites. Modified NaY zeolites have been synthesized by simple ion exchange methods. Three samples of modified zeolite Y have been obtained by replacing the sodium ions in the original sample with lanthanum and the weight percent added are 0.28, 0.53, and 1.02 respectively. The effects of addition of lanthanum to zeolite Y in different weight percent on the cracking catalysts were investigated using an experimental laboratory plant scale of fluidized bed reactor.&#x0D; The experiments have been performed with weight hourly space velocity (WHSV) range of 6 to 24 h-1, and the range of temperature from 450 to 510 oC.&#x0D; The activity of the catalyst with 1.02 wt% lanthanum has been shown to be much greater than that of the sample parent NaY. Also it was observed that the addition of the lanthanum causes an increase in the thermal stability of the zeolite.&#x0D;

An initiative towards an energy and environment scheme for Iran: Introducing RAISE (Richest Alternatives for Implementation to Supply Energy) model

Decision making in Iran's energy and environment-related issues has always been tied to complexities. Discussing these complexities and the necessity to deal with them, this paper strives to help the country with a tool by introducing Richest Alternatives for Implementation to Supply Energy (RAISE), a mixed integer linear programming model developed by the means of GNUMathprog mathematical programming language. The paper fully elaborates authors' desired modeling mentality and formulations on which RAISE is programmed to work and verifies its structure by running a widely known sample case named “UTOPIA” and comparing the results with other works including OSeMOSYS and Temoa. The model applies RAISE model to Iranian energy sector to elicit optimal policy without and with a CO2 emission cap. The results suggest promotion of energy efficiency through investment on combined cycle power plants as the key to optimal policy in power generation sector. Regarding oil refining sector, investment on condensate refineries and advanced refineries equipped with Residual Fluid Catalytic Cracking (RFCC) units are suggested. Results also undermine the prevailing supposition that climate change mitigation deteriorates economic efficiency of energy system and suggest that there is a strong synergy between them. In the case of imposing a CO2 cap that aims at maintaining CO2 emissions from electricity production activities at 2012 levels, a shift to renewable energies occurs.

Highly Effective Transformation of Methanol and RFCC Gas to Propylene and Paraxylene with Tungsten Hydride and Cerium Oxide Comodified HZSM-5 Zeolite

HZSM-5 zeolite was comodified with tungsten hydride and cerium oxide. A fixed-bed reactor was used to investigate the performance of the resulting catalysts in the transformation of methanol and residual fluid catalytic cracking (RFCC) gas to propylene and paraxylene. The resultant samples were characterized using the XRD, SEM, and BET techniques. X-ray diffraction analysis indicated the coexistence of WHx and CeO2 in the catalysts. Only at suitable methanol/RFCC gas ratios could relatively good propylene and aromatics yields be obtained. Addition of RFCC gas to methanol inhibits dry gas production while promoting the production of propylene and paraxylene and decreases the consumption of water. The methanol conversion, the propylene yield, and the paraxylene yield reached 100%, 69.5%, and 20.0%, respectively, under suitable conditions of a silica/alumina ratio of 150, a reaction temperature of 743 K, a space velocity of 10 h–1, and an RFCC gas content of 9%.

Coupling Vibration Investigation of Cyclone Separator Interacted With Unsteady Fluid

Gas–cyclone body coupling vibration is one kind of vibration caused by air pulsation. This coupling vibration causes widespread damage and deformation of three-stage cyclone separator used in residue fluid catalytic cracking. After theoretically analyzing the mechanism of the generation of the gas–cyclone body coupling vibration, the numerical simulation of three-dimensional swirling flow the cyclone separator was performed by using Reynolds stress model (RSM). The results showed the existence of precessing vortex core (PVC) in the cyclone separator. The PVC phenomenon and motion of PVC were described in detail. Furthermore, the amplitude and frequency of gas fluctuation in the PVC region at different axial positions were quantitatively analyzed. The simulation results agreed with the experimental results of laser Doppler velocimetry (LDV). Finally, characteristics of PVC in cyclone separator with a novel vortex finder were designed, and the results showed that the novel vortex finder can reduce flow vibration.

TiO2–SiO2-Composite-Supported Catalysts for Residue Fluid Catalytic Cracking Diesel Hydrotreating

Composites of TiO2–SiO2 oxides (CTS) with various Ti/Si atomic ratios were prepared by the sol–gel method, and the CO2 supercritical fluid extraction method was used to remove solvent in the gel. The effects of the Ti/Si atomic ratio and calcination temperature on the specific surface area, pore structure, acidity, and coordination status of the Ti atoms were investigated by N2 desorption, pyridine adsorption, X-ray diffraction (XRD), and X-ray absorption fine structure (XAFS), respectively. Hydrotreating catalysts were prepared with cobalt (Co)–molybdenum (Mo) and nickel (Ni)–tungsten (W) as active metal components supported on CTS-1 and CTS-4, respectively. The hydrotreating activities of the catalysts were tested by processing residue fluid catalytic cracking (RFCC) diesel on a fixed-bed reactor. It was found that hydrodesulfurization (HDS), hydrodenitrogenation (HDN), and hydrodearomatization (HDA) were affected by the acidity of the support and/or catalyst, which was related to the Ti/Si atomic ratio. The catalysts with strong Lewis acidity had better hydrotreating activities for HDS, HDN, and HDA. The study provides insight into a fundamental understanding of the relationship between the Ti/Si atomic ratio of the support and acidity of catalysts and the effect of acidity on the hydrotreating activity of the catalyst.

Crystal-Seeds-Based Strategy for the Synthesis of Hydrothermally Stable Mesoporous Aluminosilicates with a Largely Decreased H2O Amount

Recent advances in the synthesis of hydrothermally stable mesoporous aluminosilicates (MAs) by assembling precursors shed light on their applications in residue fluid catalytic cracking. Reducing the n(H2O)/n(SiO2) ratio and thus reducing waste discharge is the key for practical applications of MAs. In this study, the synthesis of hydrothermally stable MAs with a decreased n(H2O)/n(SiO2) ratio has been developed based on seed-assisted crystallization. Crystal seeds were partly dissolved to microcrystallites on which a large amount of zeolite precursors are assembled and crystallized. As a direct result of the assembly priority of crystal seeds, the concentration and viscosity of the liquid phase in the synthesis system will be decreased greatly. Afterward, the remaining precursors with proper concentration and viscosity can be assembled with the surfactant micelles. Therefore, the H2O amount could be largely decreased by the introduction of crystal seeds.

Numerical Simulation of Chemical Stripping Process in Resid Fluid Catalytic Cracking Stripper

Abstract The chemical stripping process in a commercial scale V-baffled resid fluid catalytic cracking stripper was simulated using computational fluid dynamics method. At the outset, it was assumed that the stripping steam initially desorbs hydrocarbons from the catalysts, and the hydrocarbons are then cracked through thermal and catalytic cracking reactions before entering the disengager. The Eulerian–Eulerian two-fluid model coupled with a modified drag model was applied to simulate the gas–solid flow behavior. A desorption model and five-lump kinetic model for thermal and catalytic cracking were utilized to represent the desorption and cracking processes during stripping. The flow modeling results indicated that three different flow regions exist in the stripper: bubbling flow, intermediate flow and turbulent flow. Increasing gas velocity improves the flow conditions of the gas, but adversely affects the particle flow. The degree of mixing of the gas and solid increases along the flowing direction. The results of reaction modeling showed that about 80% of hydrocarbons desorbed from the catalysts. The amount of desorbed oil increases with bed height leading to an increase of heavy oil in the disengager which induces coking problem. By increasing the catalyst temperature, the partial pressure of heavy oil can be lowered down which helps to decrease the disengager coking.

Advance in China fluid catalytic cracking (FCC) process

Since the first Chinese fluid catalytic cracking (FCC) unit was commercialized in 1965, these milestone innovations and developments have been achieved in the historical sequence events of zeolite catalyst-riser FCC process, residue FCC process, DCC (deep catalytic cracking) process, multi-cascade riser FCC process and the ongoing high-selective FCC process in China. In the course of the development of Chinese FCC technology, many breakthroughs have been made, such as the quantities of FCCU increased dramatically from the blank beginning, the technical level of FCCU enhanced higher and higher, the capacity of FCCU grew larger and larger, and the R&D on FCC technology was from the tracking mode to the independent innovation mode. Up to now, the total capacity of FCCU in China has been reached 150 Mt/a, in which the residue ratio of FCCU feedstock is around 40%. The outputs of FCCU are roughly taking up the components of 70%, 30% and 40% to gasoline pool, diesel pool and propylene pool respectively, as well as raw materials of alkylation units and etherificationunits. Now FCC is playing a decisive role in the aspects of heavy oil processing, higher light oil recovery, products qualification improving, and better economic benefits in the oil industry of China.

New Insights into Resid Desulfurization Processes: Molecular Size Dependence of Catalytic Performances Quantified by Size Exclusion Chromatography-ICP/MS

Fixed-bed resid desulfurization (RDS) is an important industrial catalytic process to produce low sulfur fuel oil and to pretreat feed for resid fluid catalytic cracking (RFCC) unit. The catalytic ...

Residue Catalytic Cracking Process for Maximum Ethylene and Propylene Production

Effects of operating conditions on residue fluid catalytic cracking (RFCC) were studied in a pilot-scale FCC unit. Experimental results indicated that both high reaction severity and long residence time promoted the production of ethylene and propylene. A novel RFCC process for maximum ethylene and propylene (MEP) production was further proposed, which was characterized by high operating severity, application of olefin-selective catalyst, and stratified reprocessing of light gasoline and butenes. Simulation experiments of the MEP process demonstrated that both light cycle gasoline and recycled butenes were effectively converted; meanwhile, the semispent catalyst still retained sufficient activity to further crack residue feedstock. When treating Daqing AR, the MEP process yielded up to 8.85 wt % ethylene and 25.97 wt % propylene. In contrast, due to elevated catalyst activity in a second-stage riser, the two-stage riser MEP process produced more propylene and LPG at the expense of light oil. Also, ethylene yield was still up to a comparative level.