Reaction performance of FCC slurry catalytic cracking

The condensation of heavy hydrocarbon causes the coke formation inside the disengager vessel. Slurry oil is the heaviest component of FCC hydrocarbon products and most likely to be condensed to form coke. Converting slurry to lighter hydrocarbons can alleviate coke formation. The slurry cracking experiments were carried out in a confined fluidized bed reactor. The results showed that the crackability of slurry was lower than that of FCC feedstock, due to the difference of their properties. About 30 wt.% heavy oil remained in the product after the slurry was cracked, but its end point declined and the heavier component decreased. The comparison of slurry cracking results at different reaction temperatures and regenerated catalyst contents indicated that the appropriate operating conditions for slurry conversion were the reaction temperature of 500 °C and the regenerated catalyst content within 25–50 wt.%.     

A novel fluid catalytic cracking approach for producing low aromatic LCO

Four FCC catalysts were compared in a CREC Riser Simulator reactor using an aromatic Brazilian VGO feed aiming at maximum low aromatic middle distillate production. Differences in activity were compensated by changes in the contact time. The first catalyst (A) was a maximum LCO commercial grade, the other three being experimental catalysts, including a pair of related materials in which one of the catalysts (M2) was produced by modulating the acidity of the other one (M1). Inert non porous silica was evaluated as a thermal cracking reference. The four catalysts were characterized as tested using temperature-programmed desorption of n-propylamine to determine their Brönsted acidity. The commercial catalyst A was by far the most acidic catalyst, followed by catalyst M1. Brönsted acidity of the two other catalysts M2 and B was about one tenth the value of catalyst A. Lowering the Brönsted acidity reduced catalyst activity, but it was possible to recover conversion by increasing reaction time, which was not the case with the thermal cracking reference. The yields of light naphtha and of aromatic hydrocarbons in the C10 and C11 range (inversely correlated to LCO Cetane) of the low acidity catalysts B and M2 was reduced by 30% and 50% respectively and LCO (C12 to C20 hydrocarbons) was increased by 33%, compared to catalyst A at the same slurry oil yield.     

Interactions of flow and reaction in fluid catalytic cracking risers

Fluid catalytic cracking (FCC) is the primary conversion process in oil refining. The performance of an FCC riser strongly depends on the interactions between oil/catalyst flow and cracking kinetics, but most FCC riser models do not consider such interactions. Accordingly, this work develops a computationally simple model capturing the dominant features of flow‐reaction coupling in the riser's dense phase and acceleration zones. Specifically, the particle–particle collision force and the particle–fluid interfacial force are considered. With a four‐lump kinetic model, the riser model predicts conversion and selectivity from the axial profile of the catalyst‐to‐oil ratio resulting from particle–fluid interfacial momentum transfer. The cracking intensity in the riser bottom zone is much greater than that calculated from conventional riser models, which neglects oil‐catalyst hydrodynamic coupling and catalyst dilution due to volume expansion. The present model compares well with published data and predicts conversion‐selectivity patterns that are qualitatively different from those obtained from conventional models. © 2011 American Institute of Chemical Engineers AIChE J, 2011     

Effects of metal modifications of Y zeolites on sulfur reduction performance in fluid catalytic cracking process

The acidity of catalytically active component, e.g., ultra stable Y zeolite (USY), plays an important role in determining their cracking activity and selectivity. To develop advanced sulfur reduction catalytic cracking catalysts, different type of elements were used to modify USY and the resulting catalysts were evaluated in a confined fluidized bed reactor and a micro-activity testing unit. The relation between the acidity of the zeolite and the conversion of sulfur compounds as well as the distributions of fluid catalytic cracking (FCC) products were discussed. The results showed that the rare earth (RE) metal can stabilize the catalyst and increase the conversion, but cannot increase the selectivity to thiophene compounds; V can reduce the sulfur content by 36.3 m%, but decreases the overall conversion compared with the base catalyst. An optimum catalyst was obtained by the combined RE and V modification, over which the sulfur content in FCC gasoline can be decreased and the selectivity for the target products can be improved, with the sulfur content reduced by 30 m% and the selectivity to coke even decreased by 0.20 m% at a comparable conversion level of the base catalyst.     

The fluidized-bed catalytic cracking unit building its future environment

Fluidized-bed catalytic cracking (FCC) has been considered as one of the largest catalytic process in the world. FCC is the name for a complex process unit that cracks long molecules from gas oils and residua into added value shorter fuel compounds; additionally, this process can be used to produce important petrochemical precursors, such as propylenes. Although historically FCC has been used to optimise production of light cycle oils, gasoline and olefins, nowadays is convenient to revisit its mission. In order to integrate FCC process inside current development and environment respect, it is necessary to see it as a very flexible process. This flexibility will require deeper knowledge about environmental impact of process operation and production objectives, transport phenomena and catalytic reactions taking place inside the riser, the main reactor of the FCC converter, and energy balance integrating energy recovered/generated in the regenerator. This work is devoted to briefly review some propositions about the use of FCC converters and how these aspects demand knowledge of riser reactors, change in the methodology to estimate effective reaction rates (consequence of variation of kinetic and transport phenomena, at catalyst scale and along the riser) and catalyst activity, as well as control actions and its effect on the energy balance of the converter; operation and environmental concerns surrounding this process are addressed. Finally, it tries to draw attention on some facts that need to be analysed in order to ensure the sustainable development of this important process in the short future.     

Effects of steaming-made changes in physicochemical properties of Y-zeolite on cracking of bulky 1,3,5-triisopropylbenzene and coke formation

The effects of acidic properties and structural changes of Y zeolite, produced by steaming, on the zeolite cracking activity, coking tendency and distribution of various products during catalytic conversion of bulky 1,3,5-triisopropylbenzene (TIPB) are reported. NaY zeolite with framework Si/Al ratio of 2.4 was synthesized by a hydrothermal method and ammonium exchanged. The zeolite was dealuminated by a temperature-programmed steaming to form USY1 and USY2 zeolites with framework Si/Al ratio of 8.1 and 12.3 respectively. The catalysts were characterized by XRD, XRF, SEM, AAS, NH₃–TPD and N₂ adsorption–desorption techniques. The samples were in-situ activated at 748 K and evaluated by TIPB cracking at 623 K. The coke content of the catalyst beds was estimated by TPO using an FT-IR gas cell. The results of activity measurements reveal that the dealuminated zeolites lead to lower cracking activity initially; while, they exhibit higher activity at longer times. In addition, a slight modification of the window diameter of Y zeolite, as revealed by pore size distribution analyses, alters the diffusion limitation of the reactant and products through the pores of the zeolite and significantly affects the adsorbent–adsorbate interactions. TPO experiments show that compared to the precursor zeolite, lower amount of coke is formed on the dealuminated catalysts possessing lower density of acid sites. However, the coke formed on USY samples is heavier than that formed on its precursor Y zeolite. This may be attributed to the larger pores shaped in the dealuminated catalysts which in turn provide suitable places for coke formation and growth.     

改性催化裂化催化剂研究进展

对催化裂化催化剂的活性组分Y型分子筛的脱铝改性及抗重金属污染改性方法和改性后的含Y型沸石的性能进行了详细介绍。重点介绍了经特殊改性的催化裂化催化剂在脱硫、多产柴油及多产丙烯等方面的用途,指出应在现有技术基础上重点开发性能更为优良的多用途催化裂化催化剂。     

催化裂化油浆利用的技术进展

概述了催化裂化油浆的组成、性质和净化技术,介绍了催化裂化油浆在石油加工、石油化工领域利用的技术进展。分析了油浆在沥青改性、与煤共处理制取沥青改进剂、溶剂脱沥青、强化蒸馏、减黏裂化和延迟焦化工艺中的应用;评述了油浆的深度分离技术及分离所得组分的利用。     

Synergetic effects of Y-zeolite and amorphous silica-alumina as main FCC catalyst components on triisopropylbenzene cracking and coke formation

The synergetic effects of HY-zeolite and silica-alumina (SA), as two major components of an FCC catalyst, on the cracking activity and coking tendency during catalytic cracking of 1,3,5-triisopropylbenzene (TiPB, as a resid representative) were studied. NaY-zeolite and SA were synthesized by hydrothermal and co-precipitation methods, respectively, and ammonium exchanged for three times at 80 °C. The catalysts were characterized by XRD, XRF, SEM, BET, AAS and ammonia TPD techniques. TiPB cracking was investigated on four different catalyst configurations including SA, Y-zeolite, SA.Y and SA-Y in a fixed bed reactor. SA.Y stands for physical mixture of equal amounts of Y-zeolite and SA. For SA-Y, a bed of SA was placed upstream of the same amount of Y-zeolite. The catalysts were in-situ activated at 475 °C and evaluated by TiPB cracking at 350 °C. The coke content of the catalyst beds, after 40 min cracking of TiPB, was estimated by TPO using an FT-IR gas cell. At 3 min time on stream, 5.2 times higher yield of benzene, as a deep cracking product, is observed on SA-Y as compared to SA.Y. The TiPB conversion decreases in the order of SA-Y > SA.Y > Y-zeolite ? SA. Furthermore, as compared to Y-zeolite, 24% lower coke is formed on SA-Y. Also CO evolution during TPO of coked SA-Y catalyst is about 24% lower than that of the coked zeolite. As a result, protecting of Y-zeolite by SA from direct exposure to resid feed enhances the cracking activity, decreases the tendency to coke formation and diminishes CO emission in the catalyst regeneration process.     

催化裂化工艺及催化剂的技术进展

介绍了国内外催化裂化工艺以及催化剂的技术进展,并对汽油降烯烃和降硫、生产低硫低芳烃柴油、多产低碳烯烃、重油转化催化裂化工艺及催化剂方面的技术现状和最新进展进行了阐述。对催化裂化工艺和催化剂的发展趋势提出了相关的建议。     

催化裂化生产清洁燃料

介绍了当前轻质油品脱硫的一些方法,包括传统的加氧脱硫和吸附脱硫等工艺过程。21 世纪的炼油企业将围绕炼油厂清洁化生产和生产更加清洁的燃料方向发展,重点发展各种汽油加氢技术并开发非加氢技术、发展轻烯烃改质以及催化汽油降烯烃技术。     

费托蜡催化裂化反应生产清洁汽油的热力学分析

费托蜡主要由链烷烃组成,不含硫、氮等杂原子,是生产清洁汽油的优质原料。由于缺少芳烃和环烷烃,费托蜡催化裂化过程需要强化异构化、芳构化反应以实现降低汽油馏分烯烃含量、保持高辛烷值的目标。对费托蜡为原料的催化裂化反应体系进行热力学分析,重点计算了不同温度下生成汽油馏分主要烃类的反应焓变和反应平衡常数。研究结果表明,以大分子链烷烃为主的费托蜡,其裂化吸热反应焓变约为80 kJ/mol,反应平衡常数随温度的升高而增大,高温有利于一次裂化反应。对于异构化反应,主要是大分子链烷烃裂化为烯烃,再由烯烃分子转化为异构烷烃,因此对于异构化反应,可以通过优化反应器促进汽油烯烃的转化。在考察温度范围内,烯烃环化反应平衡常数随温度升高而减小,环烷烃脱氢芳构化反应平衡常数随温度升高而增大,所以适宜的反应温度是制约进一步增加汽油中芳烃的重要因素。     

催化裂化轻汽油中烯烃加氢反应宏观动力学

基于流化催化裂化(FCC)轻汽油(初馏点-358 K)中所含烯烃组分的性质,将其划分为4个集总,采用管式滴流床反应器,在压力0.5-2 MPa、反应温度353-413 K、液体空速2.5-7.5 h-1的条件下,对烯烃在镍加氢催化剂上的加氢反应进行宏观动力学研究.实验结果显示:n-C4＝,n-C5＝,i-C5＝,n-C...     

流化催化裂化(FCC)催化剂跑损机制及故障树分析

炼油厂中流化催化裂化（FCC）装置催化剂跑损的故障原因分析多数来自现场工程师,在故障机理方面少有报道。为了解决这一问题,本文利用故障树分析方法（FTA）,研究FCC装置催化剂跑损机制。采用催化剂跑损为顶事件,结合跑损途径和跑损机理,确定FCC装置故障、操作工艺异常和催化剂颗粒物性3个因素作为中间事件,并通过逐层向下深入分析,确定诸如翼阀磨损等21个因素作为底事件,建立催化剂跑损故障树模型。根据FCC装置故障树风险分析,得到任何一个底事件出现都有可能导致顶事件发生,且对FCC装置催化剂跑损的贡献度相同。研究结果表明：利用FTA方法可以更深层次了解装置跑剂原因,对考察FCC装置催化剂跑损机理具有指导意义,并提出了相应的故障判定流程和跑剂预防措施。     

Single-event microkinetics for coke formation during the catalytic cracking of (cyclo)alkane/1-octene mixtures

A single-event microkinetic model (SEMK) is applied to model initial coking rates during the catalytic cracking of (cyclo)alkane/1-octene mixtures at 693–753 K and (cyclo)alkane and 1-octene inlet partial pressures of 26.6 and 4.8 kPa on a REUSY equilibrium catalyst. Three types of irreversible alkylations involving both gas phase and surface coke precursors, viz., alkylation of phenyl substituted carbenium ions with C₃–C₅ alkenes, alkylation of the nucleus of monoaromatics with C₃–C₅ alkylcarbenium ions, and alkylation of C₈–C₁₀ alkylcarbenium ions with C₃–C₅ alkenes, have been considered as rate-determining steps in coke formation. The bulky alkylated species formed out of these alkylations are considered as coke. The activation energies for these alkylations obtained via non-isothermal regression are independent of the feedstock within the parameters confidence limits reflecting the fundamental character of the SEMK. The negative effect of temperature on the experimentally observed coking rates is qualitatively described and is explained in terms of an overcompensation of the increase of the rate coefficient by a lower surface coke precursor concentration.     

钒对裂化催化剂的影响及流化催化裂化抗钒助剂的开发

研究了钒对分子筛和催化剂性能的影响 ,并开发出一种高活性固体的流化催化裂化抗钒助剂。随着钒含量的增加 ,分子筛的结晶度、比表面积、孔体积呈单调下降 ;而催化剂的催化活性大幅降低 ,选择性变差。抗钒助剂与其他类型的催化剂复配后 ,显示出较强的抗钒性能 ,能明显改善裂化产物的汽油、焦炭的选择性。     

DM-5005金属钝化剂在重油催化裂化装置上的工业应用

中国石油抚顺石油化工公司在1 500kt/a重油催化裂化装置上进行了DM-5005金属钝化剂的工业应用。结果表明,在原料油和操作条件不变的前提下,加入钝化剂后,对装置生产操作和产品质量无不良影响;干气、焦炭、油浆产率分别下降0.57,0.63,0.69百分点;液化气、汽油、液收分别提高0.96,1.75,1.2百分点;创效约11 985万元/a。DM-5005金属钝化剂能使催化剂保持良好的活性和产品选择性。     

重油催化裂化装置小型自动加料器的改进

根据加料时U型管压力平衡的原理,对第三套重油催化裂化装置小型自动加料器实施了简易改造。4年多的生产运行表明,小型自动加料器流程简单,操作方便,功能齐全,加料平稳,耐用性高,故障率低,便于维护,投资少,维护费用低。说明技术改造和工程设计是成功的。