A multiscale adaptive framework based on convolutional neural network:Application to fluid catalytic cracking product yield prediction

Since chemical processes are highly non-linear and multiscale,it is vital to deeply mine the multiscale coupling relationships embedded in the massive process data for the prediction and anomaly tracing of crucial process parameters and production indicators.While the integrated method of adaptive signal decomposition combined with time series models could effectively predict process variables,it does have limitations in capturing the high-frequency detail of the operation state when applied to complex chemical processes.In light of this,a novel Multiscale Multi-radius Multi-step Convolutional Neural Network(Msrt Net)is proposed for mining spatiotemporal multiscale information.First,the industrial data from the Fluid Catalytic Cracking(FCC)process decomposition using Complete Ensemble Empirical Mode Decomposition with Adaptive Noise(CEEMDAN)extract the multi-energy scale information of the feature subset.Then,convolution kernels with varying stride and padding structures are established to decouple the long-period operation process information encapsulated within the multi-energy scale data.Finally,a reconciliation network is trained to reconstruct the multiscale prediction results and obtain the final output.Msrt Net is initially assessed for its capability to untangle the spatiotemporal multiscale relationships among variables in the Tennessee Eastman Process(TEP).Subsequently,the performance of Msrt Net is evaluated in predicting product yield for a 2.80×10^(6) t/a FCC unit,taking diesel and gasoline yield as examples.In conclusion,Msrt Net can decouple and effectively extract spatiotemporal multiscale information from chemical process data and achieve a approximately reduction of 30%in prediction error compared to other time-series models.Furthermore,its robustness and transferability underscore its promising potential for broader applications.

HZSM-5 zeolites undergoing the high-temperature process for boosting the bimolecular reaction in n-heptane catalytic cracking

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.

Development and Catalytic Cracking Performance of Ultrastable Y Zeolite Rich in Secondary Pores

A novel ultra-stable zeolite, NSZ, rich in secondary pores was developed through the combination of gas-phase andmild hydrothermal methods. This zeolite was successfully tested in an industrial setting for the first time in the world. The porestructure characteristics of the NSZ zeolite prepared for industrial use were analyzed and characterized using BET. The resultsindicate a significant increase in the secondary pore volume of NSZ zeolite compared to the existing ultra-stable zeolite HSZ-5, which is produced through a conventional gas-phase method. The average secondary pore volume to total pore volume ratioin NSZ zeolite was found to be 58.96% higher. The catalytic cracking performance of NSZ zeolite was evaluated. The resultsshowed that the NSC-LTA catalyst, with NSZ as the active component, outperformed the HSC-LTA catalyst with HSZ-5 zeolitein terms of obtaining more high-value products (gasoline and liquefied petroleum gas) during the hydrogenated light cycle oilprocessing. Additionally, the NSC-LTA catalyst showed a significant improvement in coke selectivity.

Preparation and Electrochemical Performance Study of Catalytic Cracking Oil Slurry-based Porous Carbon Materials

Catalytic cracking oil slurry is a by-product of catalytic cracking projects,and the efficient conversion and sustainable utilization of this material are issues of continuous concern in the petroleum refining industry.In this study,oxygen-enriched activated carbon is prepared using a one-step KOH activation method with catalytic cracking oil slurry as the raw material.The as-prepared oil slurry-based activated carbon exhibits a high specific surface area of 2102 m^(2)/g,welldefined micropores with an average diameter of 2 nm,and a rich oxygen doping content of 32.97%.The electrochemical performance of the nitrogen-doped porous carbon is tested in a three-electrode system using a 6 mol/L KOH solution as the electrolyte.It achieves a specific capacitance of up to 230 F/g at a current density of 1 A/g.Moreover,the capacitance retention rate exceeds 89%after 10000 charge and discharge cycles,demonstrating excellent cycle stability.This method not only improves the utilization efficiency of industrial fuel waste but also reduces the production cost of supercapacitor electrode materials,thereby providing a simple and effective strategy for the resource utilization of catalytic cracking oil slurries.

Research Advances on Cyclohexane Catalytic Cracking

This article elaborates on the research achievements of domestic and foreign researchers in exploring the conversion pathways and reaction mechanisms of cyclohexane catalytic cracking in recent years.It analyzes the effects of different catalysts and process conditions on the conversion laws of cyclohexane,summarizes the conversion pathways of cyclohexane,and discusses the chemical mechanisms of several main reactions of cyclohexane in catalytic cracking,such as cracking,isomerization,hydrogen transfer,dehydrogenation,and alkylation;Several advanced characterization methods and common research methods were listed,and prospects for future development in this field were proposed based on existing research.

Effect of particle size of single-crystalline hierarchical ZSM-5 on its surface mass transfer in n-heptane catalytic cracking

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.

Influences of regeneration atmospheres on structural transformation and renderability of fluidized catalytic cracking catalyst

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.

Targeted Catalytic Cracking to Olefins(TCO):Reaction Mechanism,Production Scheme,and Process Perspectives

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.

Experiment and modeling of coke formation and catalyst deactivation in n-heptane catalytic cracking over HZSM-5 zeolites

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.

Fischer-Tropsch wax catalytic cracking for the production of low olefin and high octane number gasoline: Process optimization and heat effect calculation

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.

Core-shell-structured Composite ZSM-5@MCM-41 Catalysts:Fabrication,Characterization,and Enhanced Performance in Hexane Catalytic Cracking

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.

Application of New Heavy Metals Resistant Porous Binder Material Used in Fluid Catalytic Cracking Reaction

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.

Enhancing hydrothermal stability of nano-sized HZSM-5 zeolite by phosphorus modification for olefin catalytic cracking of full-range FCC gasoline

In this study, phosphorus modification by trimethyl phosphate impregnation was employed to enhance the hydrothermal stability of nano‐sized HZSM‐5 zeolites. A parallel modification was studied by ammonium dihydrogen phosphate impregnation. The modified zeolites were subjected to steam treatment at 800 °C for 4 h (100% steam) and employed as catalysts for olefin catalyticcracking (OCC) of full‐range fluid catalytic cracking (FCC) gasoline. X‐ray diffraction, N2 physicaladsorption and NH3 temperature‐programmed desorption analysis indicated that, although significantimprovements to the hydrothermal stability of nano‐sized HZSM‐5 zeolites can be observedwhen adopting both phosphorus modification strategies, impregnation with trimethyl phosphatedisplays further enhancement of the hydrothermal stability. This is because higher structural crystallinityis retained, larger specific surface areas/micropore volumes form, and there are greaternumbers of surface acid sites. Reaction experiments conducted using a fixed‐bed micro‐reactor(catalyst/oil ratio = 4, time on stream = 4 s) showed OCC of full‐range FCC gasoline-under a fluidized‐bed reaction mode configuration-to be a viable solution for the olefin problem of FCC gasoline.This reaction significantly decreased the olefin content in the full‐range FCC gasoline feed, andspecifically heavy‐end olefins, by converting the olefins into value‐added C2–C4 olefins and aromatics.At the same time, sulfide content of the gasoline decreased via a non‐hydrodesulfurization process.Nano‐sized HZSM‐5 zeolites modified with trimethyl phosphate exhibited enhanced catalytic performance for OCC of full‐range FCC gasoline.

Studies on the preliminary cracking: The reasons why matrix catalytic function is indispensable for the catalytic cracking of feed with large molecular size

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. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.

A Novel Close-loop Strategy for Integrating Process Operations of Fluidized Catalytic Cracking Unit with Production Planning Optimization

Production planning models generated by common modeling systems do not involve constraints for process operations, and a solution optimized by these models is called a quasi-optimal plan. The quasi-optimal plan cannot be executed in practice some time for no corresponding operating conditions. In order to determine a practi- cally feasible optimal plan and corresponding operating conditions of fluidized catalytic cracking unit （FCCU）, a novel close-loop integrated strategy, including determination of a quasi-optimal plan, search of operating conditions of FCCU and revision of the production planning model, was proposed in this article. In the strategy, a generalized genetic algorithm （GA） coupled with a sequential process simulator of FCCU was applied to search operating conditions implementing the quasi-optimal plan of FCCU and output the optimal individual in the GA search as a final genetic individual. When no corresponding operating conditions were found, the final genetic individual based correction （FGIC） method was presented to revise the production planning model, and then a new quasi-optimal production plan was determined. The above steps were repeated until a practically feasible optimal plan and corresponding operating conditions of FCCU were obtained. The close-loop integrated strategy was validated by two cases, and it was indicated that the strategy was efficient in determining a practically executed optimal plan and corresponding operating conditions of FCCU.

Numerical Predication of Cracking Reaction of Particle Clusters in Fluid Catalytic Cracking Riser Reactors

Behavior of catalytic cracking reactions of particle cluster in fluid catalytic cracking （FCC） riser reactors was numerically analyzed using a four-lump mathematical model. Effects of the cluster porosity, inlet gas velocity and temperature, and coke deposition on cracking reactions of the cluster were investigated. Distributions of temperature, gases, and gasoline from both catalyst particle cluster and an isolated catalyst particle are presented. The reaction rates from vacuum gas oil （VGO） to gasoline, gas and coke of individual particle in the cluster are higher than those of the isolated particle, but it reverses for the reaction rates from gasoline to gas and coke. Less gasoline is produced by particle clustering. Simulated results show that the produced mass fluxes of gas and gasoline increase with the operating temperature and molar concentration of VGO, and decrease due to the formation of coke.

Synthesis of mesoporous high‐silica zeolite Y and their catalytic cracking performance

Mesoporous high‐silica zeolite Y with advantages of improved accessibility of acid sites and mass transport properties is highly desired catalytic materials for oil refinery,fine chemistry and emerg‐ing biorefinery.Here,we report the direct synthesis of mesoporous high‐silica zeolite Y(named MSY,SiO_(2)/Al2O_(3)≥9.8)and their excellent catalytic cracking performance.The obtained MSY mate‐rials are mesoporous single crystals with octahedral morphology,abundant mesoporosity and ex‐cellent(hydro)thermal stability.Both the acid concentration and acid strength of H‐form MSY are obviously higher than those of commercial ultra‐stable Y(USY),which should be attributed to the uniform Al distribution of MSY zeolite.The H‐MSY displays an obviously reduced deactivation rate and improved catalytic activity in the cracking reaction of bulky 1,3,5‐triisopropylbenzene(TIPB),as compared with its mesoporogen‐free counterpart and USY.In addition,H‐MSY was investigated as catalyst for the cracking of industrial heavy oil.The MSY‐based catalyst(after aging at 800 oC in 100%steam for 17 h)exhibits superior conversion(7.64%increase)and gasoline yield(16.37%increase)than industrial fluid catalytic cracking(FCC)catalyst under the investigated conditions.

Fluid Catalytic Cracking Technology for Maximum Gasoline Production

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.

7-lump kinetic model for residual oil catalytic cracking

In this paper a novel 7-lump kinetic model is proposed to describe residual oil catalytic cracking, in which coke is lumped separately for accurate prediction. The reactor block is modeled as a combination of an ideal pipe flow reactor (PFR) and a continuously stirred tank reactor (CSTR). Unit factors are designed to correct the deviation between model predictions and practical plant data and tuned by modified Levenberg-Marquardt algorithm. The parameters estimated are reliable and good agreement between the model predictions and plant observations is observed. The model helps us get good insight into the per- formance of an industrial riser reactor that would be useful for optimization of residual oil catalytic cracking.

In-situ Synthesis and Catalytic Properties of ZSM-5/Rectorite Composites as Propylene Boosting Additive in Fluid Catalytic Cracking Process

Using rectorite extrudates from calcined rectorite powder as the starting material, a series of ZSM-5/rectorite composites were prepared via the in-situ crystallization method. The physicochemical properties and propylene boosting performance of the resulting samples were characterized by using X-ray diffraction, scan- ning electronic microscopy/energy dispersive spectrometer, N2 adsorption-desorption, and Fourier transformed in/tared spectroscopy of pyndine adsorption, respectively, and assessed by using Daqing atmospheric residue as Iced- stock. The results showed that the ZSM-5/rectorite composites in which the ZSM-5 phase grows inositu as a 2-3 p,m thick layer on rectorite particles have a trimodal microporous-mesoporous-macroporous structure and thus exhibit outstanding propylene boosting performance. Compared with a commercial ZSM-5 incorporated fluid catalytic cracking catalyst, the ZSM-5/rectorite composite incorporated catalyst increased the yield and selectivity of propylene by 2.44% and 5.35%, respectively.