High-temperature treatment is key to the preparation of zeolite catalysts.Herein,the effects of hightemperature treatment on the property and performance of HZSM-5 zeolites were studied in this work.X-Ray diffraction,...High-temperature treatment is key to the preparation of zeolite catalysts.Herein,the effects of hightemperature treatment on the property and performance of HZSM-5 zeolites were studied in this work.X-Ray diffraction,N2physisorption,27Al magic angle spinning nuclear magnetic resonance(MAS NMR),and temperature-programmed desorption of ammonia results indicated that the hightemperature treatment at 650℃ hardly affected the inherent crystal and texture of HZSM-5zeolites but facilitated the conversion of framework Al to extra-framework Al,reducing the acid site and enhancing the acid strength.Moreover,the high-temperature treatment improved the performance of HZSM-5 zeolites in n-heptane catalytic cracking,promoting the conversion and light olefins yield while inhibiting coke formation.Based on the kinetic and mechanism analysis,the improvement of HZSM-5 performance caused by high-temperature treatment has been attributed to the formation of extra-framework Al,which enhanced the acid strength,facilitated the bimolecular reaction,and promoted the entropy change to overcome a higher energy barrier in n-heptane catalytic cracking.展开更多
To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent flu...To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.展开更多
Since paraffins catalytic cracking was of significant importance to light olefins and aromatics production,this work was intended to gain insights into the feature and model of coke formation and catalyst deactivation...Since paraffins catalytic cracking was of significant importance to light olefins and aromatics production,this work was intended to gain insights into the feature and model of coke formation and catalyst deactivation in n-heptane catalytic cracking over HZSM-5 zeolites. 18 tests of n-heptane catalytic cracking were designed and carried out over HZSM-5 zeolites in a wide range of operating conditions. A particular attention was paid to the measurement of the conversion, product distribution, coke content, and the porosity and acidity of the fresh and spent HZSM-5 zeolites. It was found that alkene and aromatic promoted coke formation, and it reduced the pore volume and acid site of HZSM-5 zeolites, tailoring its performance in n-heptane catalytic cracking. The specific relationship between HZSM-5 zeolites, n-heptane conversion, product distribution and coke formation was quantitively characterized by the exponential and linear function. Based on the reaction network, the coupled scheme of coke formation and catalyst deactivation were specified for n-heptane catalytic cracking. The dual-model was proposed for the process simulation of n-heptane catalytic cracking over HZSM-5 zeolites. It predicted not only the conversion and product distribution but also coke content with the acceptable errors.展开更多
Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-h...Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.展开更多
Light olefins are important organic building blocks in the chemicals industry.The main low-carbon olefin production methods,such as catalytic cracking and steam cracking,have considerable room for improvement in their...Light olefins are important organic building blocks in the chemicals industry.The main low-carbon olefin production methods,such as catalytic cracking and steam cracking,have considerable room for improvement in their utilization of hydrocarbons.This review provides a thorough overview of recent studies on catalytic cracking,steam cracking,and the conversion of crude oil processes.To maximize the production of light olefins and reduce carbon emissions,the perceived benefits of various technologies are examined.Taking olefin generation and conversion as a link to expand upstream and downstream processes,a targeted catalytic cracking to olefins(TCO)process is proposed to meet current demands for the transformation of oil refining into chemical production.The main innovations of this process include a multiple feedstock supply,the development of medium-sized catalysts,and a diameter-transformed fluidizedbed reactor with different feeding schemes.In combination with other chemical processes,TCO is expected to play a critical role in enabling petroleum refining and chemical processes to achieve low carbon dioxide emissions.展开更多
The regeneration of fluidized catalytic cracking(FCC)catalysts is an essential process in petroleum processing.The current study focused the regeneration reaction characteristics of spent fluidized catalytic cracking ...The regeneration of fluidized catalytic cracking(FCC)catalysts is an essential process in petroleum processing.The current study focused the regeneration reaction characteristics of spent fluidized catalytic cracking catalyst(SFCC)at different atmospheres with influences on pore evolution and activity,for a potential way to reduce emission,produce moderate chemical product(CO),and maintain catalyst activity.The results show that regeneration in air indicates a satisfaction on removing coke on the catalyst surface while giving a poor effect on eliminating the coke inside micropores.This is attributed that the combustion in air led to a higher temperature and further transformed kaolinite phase to silicaaluminum spinel crystals,which tended to collapse and block small pores or expand large pores,with similar results observed in pure O_(2)atmosphere.Nevertheless,catalysts regenerated in O_(2)/CO_(2)diminished the combustion damage to the pore structure,of which the micro porosity after regeneration increased by 32.4% and the total acid volume rose to 27.1%.The regeneration in pure CO_(2)displayed low conversion rate due to the endothermic reaction and low reactivity.The coexistence of gasification and partial oxidation can promote regeneration and maintain the original structure and good reactivity.Finally,a mechanism of the regeneration reaction at different atmospheres was revealed.展开更多
A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an...A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an ultradilute solution. Extensive characterization techniques, including XRD, TEM, N_(2) adsorption-desorption, NH_(3)-TPD, and IR measurements, confirmed the successful coating of a microporous ZSM-5 core with a mesoporous MCM-41 shell layer and were further employed to explore the textural properties and acidic properties of the samples. The hexane cracking results revealed a significant enhancement in olefin yields after introducing the MCM-41 shell to ZSM-5. Interestingly, a volcanic trend in olefin yields was observed with the increase in the shell thickness. In particular, the highest olefin yield of 51.5%, exceeding that of the core catalyst by 17.1%, was achieved when the shell thickness was controlled at 40 nm.Moreover, the catalyst lifetime investigation revealed that the core-shell composite catalyst exhibited a minimal reduction in hexane conversion of merely 3.8% over a 120 h reaction period, significantly outperforming the 11.3% reduction exhibited by the core catalyst. This remarkable catalytic performance was attributed to the passivation of external acid sites and the introduction of more developed pore channels by the shell, which effectively mitigated unwanted side reactions. The successful synthesis of these core-shell structured catalysts presents a novel strategy for improving catalytic performance in hexane cracking, in addition to serving as a solid foundation for the design of industrial catalysts for light naphtha cracking.展开更多
A novel porous binder was obtained from acid-treated kaolin. This new binder possessed abundant meso/macropores, good hydrothermal stability and heavy metal resistance. The prepared catalyst using new binder featured ...A novel porous binder was obtained from acid-treated kaolin. This new binder possessed abundant meso/macropores, good hydrothermal stability and heavy metal resistance. The prepared catalyst using new binder featured low attrition index and large pore volume. The catalysts were contaminated with Ni, V, and tested in a fixed-fluidized bed reactor unit. In comparison with the reference sample, the oil conversion achieved by the above-mentioned catalyst increased by 3.50 percentage points, and heavy oil yield decreased by 2.86 percentage points, while the total liquid yield and light oil yield increased by 2.82 percentage points and 0.79 percentage points, respectively. The perfect pore structure, good hydrothermal stability and heavy metal resistant performance of new binder were the possible causes leading to its outstanding performance.展开更多
The matrix catalytic function when cracking the feed oil with large molecular size was systematically studied using three different catalyst configurations,including staged bed,partly mixed bed and completely mixed be...The matrix catalytic function when cracking the feed oil with large molecular size was systematically studied using three different catalyst configurations,including staged bed,partly mixed bed and completely mixed bed.Results showed that molecules in the feed oil with large molecular size indeed preferred to be first precracked on the matrix surface and then entered into the zeolite pores during the practical reaction process.Furthermore,the matrix catalytic function exhibited a great matrix-precracking ability to large feed molecules,which considerably increased the catalyst activity and the light oil selectivity.Besides the much better accessibility,the matrix-precracking ability was also from the similar capability to crack large feed hydrocarbons into the moderate fragments with that of the zeolite component.More interestingly,the interactions between the matrix catalytic function and the zeolite catalytic function made the catalyst not only exhibit much more catalytic advantages of the zeolite component,but also retain the matrix-precracking ability.As a result,the interactions enhanced the catalyst activity and improved the product distribution at the same time.The matrix catalytic function is indispensable for the catalytic cracking of feed with large molecular size,although the matrix component itself presented an inferior catalytic performance than the zeolite component did.展开更多
Increasing gasoline production in FCC unit can improve the utilization efficiency of petroleum resources and gain economic benefit.This paper discusses the technical principles for increasing FCC gasoline yield from t...Increasing gasoline production in FCC unit can improve the utilization efficiency of petroleum resources and gain economic benefit.This paper discusses the technical principles for increasing FCC gasoline yield from the aspects of feedstock properties,operating conditions,LCO(light cycle oil)recycling,catalyst selection and reactor type,and illustrates the industrial application examples for maximizing gasoline production.The technical measures,such as optimizing the feedstock,properly increasing the catalyst activity and reaction temperature,recycling LCO or hydrotreated LCO,applying high gasoline yield catalyst,and adopting the two-zone riser reactor,are proposed to enhance the gasoline yield.展开更多
Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the...Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the wellknown carbenium ion chemistry, hydride transfer forming and consuming allylic carbenium ions in the aromatization of cycloparaffins are further investigated and differentiated. The reversibility of endocyclic β-scission and cyclization reactions is refined by accounting explicitly for the reacting olefins and resulting cycloparaffins in the corresponding thermodynamics. 24 activation energies for the reactions involved in the cracking of cycloparaffins are obtained by the regression of 15 sets of experimental data upon taking the resulting 37 main cracking products, i. e., responses into account. The enhanced SEMK model can adequately describe the catalytic behavior of 37 main products with conversion and temperature.展开更多
The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds ...The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds in four distillates of Fushun shale oil,and their catalytic cracking performance was investigated.There are nine classes of basic nitrogen compounds(BNCs)and eleven classes of non-basic heteroatomic compounds(NBHCs)in the different distillates.The dominant BNCs are mainly basic N1 class species.The dominant NBHCs are mainly acidic O2 and O1 class species in the300-350℃,350-400℃,and 400-450℃distillates,while the neutral N1,N1 O1 and N2 compounds become relatively abundant in the>450℃fraction.The basic N1 compounds and acidic O1 and O2 compounds are separated into different distillates by the degree of alkylation(different carbon number)but not by aromaticity(different double-bond equivalent values).The basic N1 O1 and N2 class species and neutral N1 and N2 class species are separated into different distillates by the degrees of both alkylation and aromaticity.After the catalytic cracking of Fushun shale oil,the classes of BNCs in the liquid products remain unchanged,while the classes and relative abundances of NBHCs vary significantly.展开更多
Residue deep hydrotreating(RDHT)process was developed by the Research Institute of Petroleum Processing(RIPP)to provide high quality feedstock for deep catalytic cracking(DCC)process.In this research work,the effects ...Residue deep hydrotreating(RDHT)process was developed by the Research Institute of Petroleum Processing(RIPP)to provide high quality feedstock for deep catalytic cracking(DCC)process.In this research work,the effects of RDHT process and reaction severity on heteroatom removal,hydrogen content increase,hydrocarbon composition improvement,and DCC product yields were studied.It was showed that the RDHT process can effectively reduce heteroatoms,increase hydrogen content and improve the hydrocarbon compositions,which can contribute to an increase of light olefins yield in DCC unit.展开更多
The catalytic cracking of 1-hexene,1-heptene,1-octene,1-nonene,1-decene,and five olefins mixed with benzene,over USY catalysts was conducted in a small fixed fluidized bed reactor to study the conversion of benzene un...The catalytic cracking of 1-hexene,1-heptene,1-octene,1-nonene,1-decene,and five olefins mixed with benzene,over USY catalysts was conducted in a small fixed fluidized bed reactor to study the conversion of benzene under catalytic cracking conditions.Benzene mainly alkylated with C_(2)-C_(5)light olefins,generating monosubstituted alkylbenzenes,and the concentration of light olefins dramatically affected the alkylbenzene yield.Due to the limitation of thermodynamic equilibrium,the yield of benzene alkylation to alkylbenzene in catalytic cracking was in a relative low level.The equilibrium constant of benzene alkylation decreases with the increasing reaction temperature which resulted in reduction of alkyl benzene yield.展开更多
Although naphthenes have long been identified as important feedstock components for the production of light olefins and aromatics in fluid catalytic cracking units,their cacking mechanism and microscopic reaction netw...Although naphthenes have long been identified as important feedstock components for the production of light olefins and aromatics in fluid catalytic cracking units,their cacking mechanism and microscopic reaction networks,such as activation modes,ring-opening paths,and the production of aromatics,remain debated.In this context,we reported experimental and computational work aimed at elucidating the reaction network of naphthenes in fluid catalytic cracking using cyclohexane as the model naphthene.First,the main reactions for the formation of highly selective and value-added products such as light olefins and aromatics were discussed.Then,the proportions of cyclohexane activation via(i)the non-classical carbonium mechanism and(ii)the classical carbenium mechanism were analyzed by data fitting methods,which revealed that around 32.6%of cyclohexane was initiated by path(i),and the remaining naphthene was activated by path(ii).Moreover,our DFT results showed that the ring opening of cyclohexane through pathway(i)was more difficult than that through path(ii),and ring opening followed by the ring contraction of cyclohexane carbenium ions was the most energetically favorable route among the different ring-opening ways.展开更多
Fluid catalytic cracking(FCC)is a vitally important refinery process.The fractionation,absorption,and stabilization system in the FCC process is a significant way to obtain key products,and its parameters will directl...Fluid catalytic cracking(FCC)is a vitally important refinery process.The fractionation,absorption,and stabilization system in the FCC process is a significant way to obtain key products,and its parameters will directly affect the quality of the products.In this work,using industrial data from an actual FCC process,a model of the FCC fractionation,absorption,and stabilization system was developed using process simulation software.The sequence quadratic program algorithm was then used to identify the parameters of each tower,increasing the accuracy of the simulation results.Next,using this improved model,a sensitivity analysis was performed to examine the effects of different operating conditions.The pattern-search method was then used to optimize the operating parameters of the system.The results showed that the optimized model has good prediction accuracy,and using the model,it was found that changing the operation parameters could result in a 1.84%improvement in economic benefits.As such,the developed model was demonstrated to be usefully applicable to the optimization of the process operation of an FCC fractionation,absorption,and stabilization system.展开更多
Fluid catalytic cracking(FCC)technologies of downer reactors,which have reached the demonstration or commercial scale,are systematically discussed,i.e.,millisecond catalytic cracking,fluidization lab of Tsinghua Unive...Fluid catalytic cracking(FCC)technologies of downer reactors,which have reached the demonstration or commercial scale,are systematically discussed,i.e.,millisecond catalytic cracking,fluidization lab of Tsinghua University,and high-severity FCC.Moreover,aiming to promote industrial application,the fundamental studies are comprehensively described,particularly focusing on high-density downer reactors,clusters,and up-scaling.Furthermore,from the perspective of industrial application,some research directions toward further developments are suggested.展开更多
Polypropylene (PP) is rated first as volume leader in the plastic sector. Its non-biodegradable property poses serious environmental problem in case of disposal. The catalytic cracking of PP was performed with various...Polypropylene (PP) is rated first as volume leader in the plastic sector. Its non-biodegradable property poses serious environmental problem in case of disposal. The catalytic cracking of PP was performed with various catalysts i.e. ZSM-5, Zeolite, RB and SPS. The cracking was observed under different feed to catalyst ratio i.e. 1:1 to 5:1. The fluidized bed reactor was fabricated with arrangement to measure the temperature ranging from 100<sup>。</sup>C to 800<sup>。</sup>C. The effective of feed to catalyst ratio was found 3:1 at a temperature range of 420<sup>。</sup>C - 510<sup>。</sup>C and catalyst ZSM-5 gives maximum liquid conversion of waste PP. Conversion of PP to liquid fuel will not only resolve the problem of disposal of waste polypropylene plastic but also give a value aided product.展开更多
Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 ze...Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.展开更多
A novel heavy oil catalytic cracking catalyst RCC-1 was developed by using the ultra-stable zeolite, which was hydrothermally treated and modified through cleaning its pores to serve as the active component. The chemi...A novel heavy oil catalytic cracking catalyst RCC-1 was developed by using the ultra-stable zeolite, which was hydrothermally treated and modified through cleaning its pores to serve as the active component. The chemical composition and physicochemical properties of RCC-1 catalyst were studied by XRF, BET, pore volume analysis, attrition index analysis, and particle size distribution determination methods, and its catalytic cracking performance was also evaluated by a microreactor for light oil cracking and the ACE device. The test results showed that the new type of heavy oil catalytic cracking catalyst RCC-1 had good physicochemical properties and heavy oil cracking ability, strong anti-metallic contamination capability, good product distribution, good coke selectivity and gasoline selectivity, and excellent reduction of gasoline olefin content characteristics.展开更多
基金the financial support from the National Natural Science Foundation of China(21908010)Jilin Provincial Department of Science and Technology(20220101089JC)the Education Department of Jilin Province(JJKH20220694KJ)。
文摘High-temperature treatment is key to the preparation of zeolite catalysts.Herein,the effects of hightemperature treatment on the property and performance of HZSM-5 zeolites were studied in this work.X-Ray diffraction,N2physisorption,27Al magic angle spinning nuclear magnetic resonance(MAS NMR),and temperature-programmed desorption of ammonia results indicated that the hightemperature treatment at 650℃ hardly affected the inherent crystal and texture of HZSM-5zeolites but facilitated the conversion of framework Al to extra-framework Al,reducing the acid site and enhancing the acid strength.Moreover,the high-temperature treatment improved the performance of HZSM-5 zeolites in n-heptane catalytic cracking,promoting the conversion and light olefins yield while inhibiting coke formation.Based on the kinetic and mechanism analysis,the improvement of HZSM-5 performance caused by high-temperature treatment has been attributed to the formation of extra-framework Al,which enhanced the acid strength,facilitated the bimolecular reaction,and promoted the entropy change to overcome a higher energy barrier in n-heptane catalytic cracking.
基金supported by the National Key Research and Development Program of China(2017YFB0602504)the General Program of National Natural Science Foundation of China(22178385).
文摘To produce low olefin gasoline with high octane number by Fischer-Tropsch (F-T) wax fluid catalytic cracking (FCC) process, operating conditions optimization were carried out in the pilot-scale riser and turbulent fluidized bed (TFB) FCC unit. The experimental results in the riser indicated that under the condition of low reaction temperature and regenerated catalyst temperature, large catalyst-to-oil weight ratio (C/O) and long reaction time, the gasoline olefin content could be reduced to 20.28 wt%, but there is large octane number loss owing to a great loss in high octane number olefin. Therefore, a novel FCC process using the TFB reactor was proposed to strengthen the aromatization reaction. The reaction performance of TFB reactor were investigated. The result demonstrated that the TFB reactor has more significant effect in reducing olefins and improving aromatics. At the expense of certain gasoline yield, the gasoline olefin content reduced to 23.70 wt%, aromatics content could increase to 26.79 wt% and the RON was up to 91.0. The comparison of reactor structure and fluidization demonstrated that the TFB reactor has higher catalyst bed density. The reaction heat and coke combustion heat was calculated indicating the feasibility of its industrial application of the TFB process.
基金the financial support from the National Natural Science Foundation of China (21908010)the Education Department of Jilin Province (JJKH20220694KJ)。
文摘Since paraffins catalytic cracking was of significant importance to light olefins and aromatics production,this work was intended to gain insights into the feature and model of coke formation and catalyst deactivation in n-heptane catalytic cracking over HZSM-5 zeolites. 18 tests of n-heptane catalytic cracking were designed and carried out over HZSM-5 zeolites in a wide range of operating conditions. A particular attention was paid to the measurement of the conversion, product distribution, coke content, and the porosity and acidity of the fresh and spent HZSM-5 zeolites. It was found that alkene and aromatic promoted coke formation, and it reduced the pore volume and acid site of HZSM-5 zeolites, tailoring its performance in n-heptane catalytic cracking. The specific relationship between HZSM-5 zeolites, n-heptane conversion, product distribution and coke formation was quantitively characterized by the exponential and linear function. Based on the reaction network, the coupled scheme of coke formation and catalyst deactivation were specified for n-heptane catalytic cracking. The dual-model was proposed for the process simulation of n-heptane catalytic cracking over HZSM-5 zeolites. It predicted not only the conversion and product distribution but also coke content with the acceptable errors.
基金The support from the National Natural Science Foundation of China(22278353)is greatly appreciated。
文摘Single-crystalline hierarchical ZSM-5 zeolites with different particle sizes(namely 100,140,and 200 nm)were successfully prepared by adjusting the amount of tetrapropylammonium hydroxide(TPAOH),and investigated in n-heptane catalytic cracking reaction.Diffusional measurements by zero-length column(ZLC)method showed that the apparent diffusivities of n-heptane decreased with the reduction of particle size,indicating the existence of surface barriers.Moreover,with the decrease of particle size,the additional diffusion path length increased,which meant the influence of surface barriers became more apparent.Despite the change of surface barriers,the intracrystalline diffusion still dominated the overall diffusion.Catalytic performance showed that the zeolite with smaller particle size had better stability.
基金financially supported by a research grant from the National Key Research and Development Program of China(2021YFA1501204)China Petroleum and Chemical Corporation(Sinopec Corp.),China(ST22001)。
文摘Light olefins are important organic building blocks in the chemicals industry.The main low-carbon olefin production methods,such as catalytic cracking and steam cracking,have considerable room for improvement in their utilization of hydrocarbons.This review provides a thorough overview of recent studies on catalytic cracking,steam cracking,and the conversion of crude oil processes.To maximize the production of light olefins and reduce carbon emissions,the perceived benefits of various technologies are examined.Taking olefin generation and conversion as a link to expand upstream and downstream processes,a targeted catalytic cracking to olefins(TCO)process is proposed to meet current demands for the transformation of oil refining into chemical production.The main innovations of this process include a multiple feedstock supply,the development of medium-sized catalysts,and a diameter-transformed fluidizedbed reactor with different feeding schemes.In combination with other chemical processes,TCO is expected to play a critical role in enabling petroleum refining and chemical processes to achieve low carbon dioxide emissions.
基金supported by the National Natural Science Foundation of China(21908063)the Shanghai Pujiang Program(21PJ1402300)the Fundamental Research Funds of the Central Universities(JKB01211715 and JKB01221677)。
文摘The regeneration of fluidized catalytic cracking(FCC)catalysts is an essential process in petroleum processing.The current study focused the regeneration reaction characteristics of spent fluidized catalytic cracking catalyst(SFCC)at different atmospheres with influences on pore evolution and activity,for a potential way to reduce emission,produce moderate chemical product(CO),and maintain catalyst activity.The results show that regeneration in air indicates a satisfaction on removing coke on the catalyst surface while giving a poor effect on eliminating the coke inside micropores.This is attributed that the combustion in air led to a higher temperature and further transformed kaolinite phase to silicaaluminum spinel crystals,which tended to collapse and block small pores or expand large pores,with similar results observed in pure O_(2)atmosphere.Nevertheless,catalysts regenerated in O_(2)/CO_(2)diminished the combustion damage to the pore structure,of which the micro porosity after regeneration increased by 32.4% and the total acid volume rose to 27.1%.The regeneration in pure CO_(2)displayed low conversion rate due to the endothermic reaction and low reactivity.The coexistence of gasification and partial oxidation can promote regeneration and maintain the original structure and good reactivity.Finally,a mechanism of the regeneration reaction at different atmospheres was revealed.
基金sponsored financially by the National Natural Science Foundation of China (Grant No. 21776076)the Fundamental Research Funds for the Central Universities (Grant No. JKA01211710)。
文摘A series of core-shell zeolites with a ZSM-5 zeolite core and a MCM-41 shell with varying shell thicknesses were successfully fabricated via a cetyltrimethylammonium bromide(CTAB)-directed sol-gel coating method in an ultradilute solution. Extensive characterization techniques, including XRD, TEM, N_(2) adsorption-desorption, NH_(3)-TPD, and IR measurements, confirmed the successful coating of a microporous ZSM-5 core with a mesoporous MCM-41 shell layer and were further employed to explore the textural properties and acidic properties of the samples. The hexane cracking results revealed a significant enhancement in olefin yields after introducing the MCM-41 shell to ZSM-5. Interestingly, a volcanic trend in olefin yields was observed with the increase in the shell thickness. In particular, the highest olefin yield of 51.5%, exceeding that of the core catalyst by 17.1%, was achieved when the shell thickness was controlled at 40 nm.Moreover, the catalyst lifetime investigation revealed that the core-shell composite catalyst exhibited a minimal reduction in hexane conversion of merely 3.8% over a 120 h reaction period, significantly outperforming the 11.3% reduction exhibited by the core catalyst. This remarkable catalytic performance was attributed to the passivation of external acid sites and the introduction of more developed pore channels by the shell, which effectively mitigated unwanted side reactions. The successful synthesis of these core-shell structured catalysts presents a novel strategy for improving catalytic performance in hexane cracking, in addition to serving as a solid foundation for the design of industrial catalysts for light naphtha cracking.
基金the Department of Science and Technology Management of PetroChina for providing financial support
文摘A novel porous binder was obtained from acid-treated kaolin. This new binder possessed abundant meso/macropores, good hydrothermal stability and heavy metal resistance. The prepared catalyst using new binder featured low attrition index and large pore volume. The catalysts were contaminated with Ni, V, and tested in a fixed-fluidized bed reactor unit. In comparison with the reference sample, the oil conversion achieved by the above-mentioned catalyst increased by 3.50 percentage points, and heavy oil yield decreased by 2.86 percentage points, while the total liquid yield and light oil yield increased by 2.82 percentage points and 0.79 percentage points, respectively. The perfect pore structure, good hydrothermal stability and heavy metal resistant performance of new binder were the possible causes leading to its outstanding performance.
基金supported by the National Natural Science Foundation of China(U146220521476263+3 种基金21406270)the Fundamental Research Funds for the Central Universities(15CX06036A)the China University of Petroleum for Postgraduate Technology Innovation Project(YCX2015028)the Qingdao People’s Livelihood Project(13-1-3-126-nsh)
文摘The matrix catalytic function when cracking the feed oil with large molecular size was systematically studied using three different catalyst configurations,including staged bed,partly mixed bed and completely mixed bed.Results showed that molecules in the feed oil with large molecular size indeed preferred to be first precracked on the matrix surface and then entered into the zeolite pores during the practical reaction process.Furthermore,the matrix catalytic function exhibited a great matrix-precracking ability to large feed molecules,which considerably increased the catalyst activity and the light oil selectivity.Besides the much better accessibility,the matrix-precracking ability was also from the similar capability to crack large feed hydrocarbons into the moderate fragments with that of the zeolite component.More interestingly,the interactions between the matrix catalytic function and the zeolite catalytic function made the catalyst not only exhibit much more catalytic advantages of the zeolite component,but also retain the matrix-precracking ability.As a result,the interactions enhanced the catalyst activity and improved the product distribution at the same time.The matrix catalytic function is indispensable for the catalytic cracking of feed with large molecular size,although the matrix component itself presented an inferior catalytic performance than the zeolite component did.
文摘Increasing gasoline production in FCC unit can improve the utilization efficiency of petroleum resources and gain economic benefit.This paper discusses the technical principles for increasing FCC gasoline yield from the aspects of feedstock properties,operating conditions,LCO(light cycle oil)recycling,catalyst selection and reactor type,and illustrates the industrial application examples for maximizing gasoline production.The technical measures,such as optimizing the feedstock,properly increasing the catalyst activity and reaction temperature,recycling LCO or hydrotreated LCO,applying high gasoline yield catalyst,and adopting the two-zone riser reactor,are proposed to enhance the gasoline yield.
基金financial support from the China Scholarship Councilthe Long Term Structural Methusalem Funding by the Flemish Government
文摘Single-event microkinetic(SEMK) model of the catalytic cracking of methylcyclohexane admixed with 1-octene over REUSY zeolites at 693 K—753 K in the absence of coke formation is enhanced. To keep consistency with the wellknown carbenium ion chemistry, hydride transfer forming and consuming allylic carbenium ions in the aromatization of cycloparaffins are further investigated and differentiated. The reversibility of endocyclic β-scission and cyclization reactions is refined by accounting explicitly for the reacting olefins and resulting cycloparaffins in the corresponding thermodynamics. 24 activation energies for the reactions involved in the cracking of cycloparaffins are obtained by the regression of 15 sets of experimental data upon taking the resulting 37 main cracking products, i. e., responses into account. The enhanced SEMK model can adequately describe the catalytic behavior of 37 main products with conversion and temperature.
基金supported by the National Natural Science Foundation of China(21776312)。
文摘The positive-and negative-ion electrospray ionization(ESI)coupled with Fourier transform-ion cyclotron resonance mass spectrometry(FT-ICR MS)was employed to identify the chemical composition of heteroatomic compounds in four distillates of Fushun shale oil,and their catalytic cracking performance was investigated.There are nine classes of basic nitrogen compounds(BNCs)and eleven classes of non-basic heteroatomic compounds(NBHCs)in the different distillates.The dominant BNCs are mainly basic N1 class species.The dominant NBHCs are mainly acidic O2 and O1 class species in the300-350℃,350-400℃,and 400-450℃distillates,while the neutral N1,N1 O1 and N2 compounds become relatively abundant in the>450℃fraction.The basic N1 compounds and acidic O1 and O2 compounds are separated into different distillates by the degree of alkylation(different carbon number)but not by aromaticity(different double-bond equivalent values).The basic N1 O1 and N2 class species and neutral N1 and N2 class species are separated into different distillates by the degrees of both alkylation and aromaticity.After the catalytic cracking of Fushun shale oil,the classes of BNCs in the liquid products remain unchanged,while the classes and relative abundances of NBHCs vary significantly.
基金This work was supported by the Science and Technology Project of Sinopec(118015-1).
文摘Residue deep hydrotreating(RDHT)process was developed by the Research Institute of Petroleum Processing(RIPP)to provide high quality feedstock for deep catalytic cracking(DCC)process.In this research work,the effects of RDHT process and reaction severity on heteroatom removal,hydrogen content increase,hydrocarbon composition improvement,and DCC product yields were studied.It was showed that the RDHT process can effectively reduce heteroatoms,increase hydrogen content and improve the hydrocarbon compositions,which can contribute to an increase of light olefins yield in DCC unit.
文摘The catalytic cracking of 1-hexene,1-heptene,1-octene,1-nonene,1-decene,and five olefins mixed with benzene,over USY catalysts was conducted in a small fixed fluidized bed reactor to study the conversion of benzene under catalytic cracking conditions.Benzene mainly alkylated with C_(2)-C_(5)light olefins,generating monosubstituted alkylbenzenes,and the concentration of light olefins dramatically affected the alkylbenzene yield.Due to the limitation of thermodynamic equilibrium,the yield of benzene alkylation to alkylbenzene in catalytic cracking was in a relative low level.The equilibrium constant of benzene alkylation decreases with the increasing reaction temperature which resulted in reduction of alkyl benzene yield.
基金This work was performed with the financial support of Sinopec Research Institute of Petroleum Processing(RIPP,Proj.R17022).
文摘Although naphthenes have long been identified as important feedstock components for the production of light olefins and aromatics in fluid catalytic cracking units,their cacking mechanism and microscopic reaction networks,such as activation modes,ring-opening paths,and the production of aromatics,remain debated.In this context,we reported experimental and computational work aimed at elucidating the reaction network of naphthenes in fluid catalytic cracking using cyclohexane as the model naphthene.First,the main reactions for the formation of highly selective and value-added products such as light olefins and aromatics were discussed.Then,the proportions of cyclohexane activation via(i)the non-classical carbonium mechanism and(ii)the classical carbenium mechanism were analyzed by data fitting methods,which revealed that around 32.6%of cyclohexane was initiated by path(i),and the remaining naphthene was activated by path(ii).Moreover,our DFT results showed that the ring opening of cyclohexane through pathway(i)was more difficult than that through path(ii),and ring opening followed by the ring contraction of cyclohexane carbenium ions was the most energetically favorable route among the different ring-opening ways.
基金supported by the National Key Research&Development Program-Intergovernmental International Science and Technology Innovation Cooperation Project (Grant No.2021YFE0112800)National Natural Science Foundation of China (Grant Nos.61973124+2 种基金61873093)the SINOPEC Research Program (Grant No.119030-2)Shanghai AI Lab
文摘Fluid catalytic cracking(FCC)is a vitally important refinery process.The fractionation,absorption,and stabilization system in the FCC process is a significant way to obtain key products,and its parameters will directly affect the quality of the products.In this work,using industrial data from an actual FCC process,a model of the FCC fractionation,absorption,and stabilization system was developed using process simulation software.The sequence quadratic program algorithm was then used to identify the parameters of each tower,increasing the accuracy of the simulation results.Next,using this improved model,a sensitivity analysis was performed to examine the effects of different operating conditions.The pattern-search method was then used to optimize the operating parameters of the system.The results showed that the optimized model has good prediction accuracy,and using the model,it was found that changing the operation parameters could result in a 1.84%improvement in economic benefits.As such,the developed model was demonstrated to be usefully applicable to the optimization of the process operation of an FCC fractionation,absorption,and stabilization system.
基金the funding of the project by SINOPEC (No. 120009)
文摘Fluid catalytic cracking(FCC)technologies of downer reactors,which have reached the demonstration or commercial scale,are systematically discussed,i.e.,millisecond catalytic cracking,fluidization lab of Tsinghua University,and high-severity FCC.Moreover,aiming to promote industrial application,the fundamental studies are comprehensively described,particularly focusing on high-density downer reactors,clusters,and up-scaling.Furthermore,from the perspective of industrial application,some research directions toward further developments are suggested.
文摘Polypropylene (PP) is rated first as volume leader in the plastic sector. Its non-biodegradable property poses serious environmental problem in case of disposal. The catalytic cracking of PP was performed with various catalysts i.e. ZSM-5, Zeolite, RB and SPS. The cracking was observed under different feed to catalyst ratio i.e. 1:1 to 5:1. The fluidized bed reactor was fabricated with arrangement to measure the temperature ranging from 100<sup>。</sup>C to 800<sup>。</sup>C. The effective of feed to catalyst ratio was found 3:1 at a temperature range of 420<sup>。</sup>C - 510<sup>。</sup>C and catalyst ZSM-5 gives maximum liquid conversion of waste PP. Conversion of PP to liquid fuel will not only resolve the problem of disposal of waste polypropylene plastic but also give a value aided product.
文摘Catalytic cracking of naphtha is now a process of huge development potential to produce light olefins, which are important basic raw materials used in various industries, but current industrial catalysts like ZSM-5 zeolites suffer from low selectivity and high energy consumption. Here, Ti/Al-containing nanosize MFI-structure zeolites in-situly synthesized through one-pot method were applied to the catalytic cracking using n-hexane as the model reactant. The maximum mass yield of combined light olefins reaches 49.2% with 99% conversion at 600<span style="color:#4F4F4F;font-family:-apple-system, "font-size:16px;white-space:normal;background-color:#FFFFFF;">°</span>C and 1 atm. Multiple characterizations are used to identify the Ti-related active species and their effect on the performance. It was found that a higher proportion of LAS caused by Ti was beneficial to the activation of reactant, and the slightly increased amount of BAS leaded to more alkanes converting into light olefins. This understanding may open new opportunities for design and modification of catalytic cracking catalysts.
文摘A novel heavy oil catalytic cracking catalyst RCC-1 was developed by using the ultra-stable zeolite, which was hydrothermally treated and modified through cleaning its pores to serve as the active component. The chemical composition and physicochemical properties of RCC-1 catalyst were studied by XRF, BET, pore volume analysis, attrition index analysis, and particle size distribution determination methods, and its catalytic cracking performance was also evaluated by a microreactor for light oil cracking and the ACE device. The test results showed that the new type of heavy oil catalytic cracking catalyst RCC-1 had good physicochemical properties and heavy oil cracking ability, strong anti-metallic contamination capability, good product distribution, good coke selectivity and gasoline selectivity, and excellent reduction of gasoline olefin content characteristics.
