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.

Research on Catalytic Cracking Performance Improvement of Waste FCC Catalyst by Magnesium Modification

In this study,the deactivation mechanism caused by high accessibility of strong acid sites for the waste FCC catalyst was proposed and verified for the first time.Based on the proposed deactivation mechanism,magnesium modification through magnesium chloride impregnation was employed for the regeneration of waste FCC catalyst.The regenerated waste FCC catalyst was characterized,with its heavy oil catalytic cracking performance tested.The characterization results indicated that,in comparison with the unmodified waste FCC catalyst,the acid sites strength of the regenerated waste FCC catalyst was weakened,with no prominent alterations of the total acid sites quantity and textural properties.The heavy oil catalytic cracking results suggested that the catalytic cracking performance of the regenerated waste FCC catalyst was greatly improved due to the suitable surface acidity of the sample.In contrast with the unmodified waste FCC catalyst,the gasoline yield over the regenerated waste FCC catalyst significantly increased by 3.04 percentage points,meanwhile the yield of dry gas,LPG,coke and bottoms obviously decreased by 0.36,0.81,1.28 and 0.87 percentage points,respectively,making the regenerated waste FCC catalyst serve as a partial substitute for the fresh FCC catalyst.Finally,the acid property change mechanism was discussed.

Preliminary Study on Reducing Olefin Content of FCC Gasoline over Cracking Catalyst

Using fixed bed micro-reactor and cracking catalyst, re-cracking of fluid catalytic cracking (FCC) gasoline at lower temperature than conventional cracking condition has been studied. The results reveal that at lower temperature from 350℃-450℃ and catalyst to feed ratio of 3, the olefin content is reduced from 49% to 27%(by mass) over the catalyst whose micro-reacting activation index is 53, and the octane number is kept on high level.

Catalytic Cracking of Cycloparaffins Admixed with Olefins:1. Single-Event Microkinetic(SEMK) Modeling

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.

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.

FCC催化剂传质强化活性位利用效率的可视化分析

流化催化裂化(FCC)催化剂传质性能抑制活性位利用效率是影响其催化性能的关键因素,选用6种不同基质材料制备的FCC催化剂样品,在系统分析催化孔结构和酸性质的基础上,利用激光共聚焦荧光显微成像技术和吸附穿透曲线法模拟考察了重油大分子的传质扩散行为;并运用单分子荧光成像技术,以B酸中心催化噻吩低聚反应生成低聚物的数量作为判据考察了系列催化剂的活性位利用效率。研究发现,相比于传统的高岭土和拟薄水铝石作为基质材料,本课题组设计开发的大孔富B酸的基质材料(APM-9)明显优化了大分子在FCC催化剂上的传质性能,从而显著提升了活性位的利用效率。发展了一种新颖的FCC催化剂结构参数与其传质性能、酸中心利用效率构效关系建立的方法,可为催化剂基质材料的设计和优化提供数据支撑和理论指导。

Catalytic Cracking of Polyolefins in the Molten Phase——Basic Study for the Process Development of Waste Plastics Liquefaction

The cracking of polyolefins, especially polyethylene in the molten state was effectively catalyzed by the powdery spent FCC （Fluid Catalytic Cracking） catalyst which was dispersed in it. The activation energy of the catalytic cracking of polyethylene was about 74 kJ/mol. The cracked product was naphtha and middle distillate as the major product and gaseous hydrocarbon （C1-C4） as the minor product while little heavy oil was produced. The chemical compositions of the product were： aromatic hydrocarbons, isoparaffins and branched olefins, whereas that of the non-catalyzed products were： n-olefins and n-paraffins with minor amount of dienes with increasing the process time. Additionally, the product pattern shifted from naphtha rich product to kerosene and gas-oil rich product. However, any catalytic product showed low fluid point （〈 -10 ℃）, while that of the non-catalyzed product was as high as 40 ℃. Catalyst could process, more than 100 times by weight of polyethylene with fairly small amount （- 30 wt%） of coke deposition. Spent catalyst gave higher hydrocarbons while fresh catalyst gave gaseous product as the major product. Other polyolefins such as polypropylene and polystyrene were tested on same catalyst to show that their reactivity is higher than that of polyethylene and gave the aliphatic products, alkyl benzenes and C6-C9 iso-paraffins as the major product. Product pattern of the cracked product suggested that the reaction proceeded via the primary reactions making paraffins and olefins which were followed by the isomerization, secondary cracking, aromatization and hydrogen transfer which based on the carbenium ion mechanism.

工艺条件对FCC轻汽油催化裂解生产低碳烯烃的影响

使用200 m L固定床反应器,在专用催化剂作用下,考察了工艺条件对催化裂化(FCC)轻汽油原料催化裂解生产低碳烯烃反应性能的影响。结果表明:在专用催化剂作用下,FCC轻汽油原料经催化裂解可制得低碳烯烃中的乙烯、丙烯和丁烯,并且产物中的m(丙烯)/m(乙烯)大于1.40,远高于其经蒸汽热裂解增产丙烯工艺下的0.43;反应温度对C_(≥5)液相产物组成中的芳烃收率增幅影响很大;较高的质量空速不利于低碳烯烃的生成;去离子水的存在及增多,不仅促进丙烯的生成,还有利于抑制催化剂结焦生炭。在反应温度为500℃、液时质量空速为1.0 h^(-1)、反应压力为0.13 MPa、注水量[m(去离子水)/m(FCC轻汽油原料)]为40%的催化裂解优化工艺条件下,丙烯、乙烯、丁烯收率分别达4.44%,9.87%,8.27%,m(丙烯)/m(乙烯)达2.22。

FCC汽油中硫分布和催化脱硫研究

对胜利石油化工总厂的FCC汽油中的硫含量、硫分布及硫化物的种类进行了分析。该汽油中的硫含量高 ,且 90 %的硫都集中在占 65 %的 10 0℃以上的汽油馏分中。采用配有PFPD检测器的色谱分析了 10 0℃以上的汽油馏分中硫化物的种类 ,结果表明 ,近 90 %的硫化物都是噻吩类化合物。对不同的汽油脱硫方法进行了分析 ,提出了汽油催化裂化脱硫全新方法 ,并开发出了具有显著脱硫效果的脱硫催化剂。

硫化物在FCC催化剂上的裂化脱硫研究

采用微反、元素分析、微库仑法和PFPD色谱等评价分析手段 ,对硫醇、硫醚、噻吩、甲基噻吩和苯并噻吩等硫化物在FCC催化剂上的裂化脱硫行为进行了研究。结果表明 ,硫醇、硫醚易于裂化脱硫 ,在实验条件下其脱硫率在 95 %左右 ;噻吩、苯并噻吩则相对较难裂化脱硫 ,两者的脱硫率均为 6 5 %;甲基噻吩比噻吩容易裂化脱硫 ,但其脱硫率低于硫醇和硫醚。苯并噻吩较容易生成含硫焦炭 ,脱除的硫中有 15 .6 %进入焦炭中 ;而其他几种硫化物生成的含硫焦炭上硫的量较少 ,都在 7%以下。此外 ,硫醇、硫醚和苯并噻吩在反应过程中除裂化和生焦反应外 ,基本上不会生成其他硫化物 ,而噻吩、甲基噻吩在反应中则会相互转化。

生产低硫汽油新型FCC催化剂研究进展

介绍了国内外低硫汽油生产技术 ,重点讨论了催化裂化过程硫转化机理及国内外脱硫FCC催化剂的研究开发现状。结果表明 :在B酸或L酸的作用下 ,通过氢转移使FCC汽油中的噻吩硫及其衍生物分解生成H2 S气体 ,以达到降低FCC汽油硫含量的目的 ,这在反应机理上是可行的 ,因此 ,开发新型FCC催化剂 ,对于实现催化裂化过程直接脱硫 ,生产低硫汽油具有实际意义。

FCC汽油非临氢脱硫技术进展

综述了国内外开发和应用的FCC汽油非临氢脱硫技术,该技术主要有生物脱硫、催化裂化脱硫、吸附脱硫、溶剂抽提脱硫、烷基化脱硫、氧化脱硫和膜分离脱硫等;评述了催化裂化脱硫、吸附脱硫和氧化脱硫等技术的特点和研究应用前景。

ZRP沸石对FCC汽油催化裂解产丙烯的影响

研究了在550℃、常压、加入水蒸气条件下,FCC汽油在ZRP沸石上的催化裂解反应和ZRP沸石硅/铝比(n(SiO2)/n(Al2O3))变化及稀土改性ZRP对反应的影响。实验结果和反应前后反应物与产物分布的计算结果表明,FCC汽油中烯烃进行裂化反应生成丙烯。提高烯烃的选择性转化、促进裂化反应并提高丙烯产物的选择性,有利于提高丙烯产率。提高ZRP沸石的n(SiO2)/n(Al2O3)能够增加其强酸量,使烯烃的转化率和低碳烯烃的选择性有所提高,但丁烯选择性高于丙烯的选择性。采用稀土改性也可使ZRP沸石增加强酸量,提高烯烃的转化率和丙烯的选择性,使74.32%的烯烃被转化,裂解汽油烯烃质量分数为18.20%,丙烯选择性达到45.91%。

FCC轻汽油催化裂化生产丙烯反应规律的研究

在提升管实验装置和脉冲色谱装置上,采用ZSM-5催化剂,考察了不同条件下FCC轻汽油和2M-1-C=5的裂化。结果表明,催化裂化过程添加ZSM-5催化剂可提高汽油中C=5、C=6的质量分数。轻汽油裂化生产丙烯的性能优于重汽油和全馏分汽油,在相对低的温度下瞬时反应能得到较高的丙烯收率。在脉冲色谱装置上,反应温度和载气流量对轻汽油和2M-1-C=5裂化生产丙烯的影响一致,即反应温度升高,载气流量降低,丙烯收率增加。提高反应温度,延长停留时间可以提高丙烯对丁烯的比例。轻汽油在ZSM-5催化剂上反应,催化剂结焦失活速度开始较快,后来减缓。ZSM-5催化剂结焦失活对丙烯生成的抑制作用大于对丁烯的抑制作用,ZSM5-的强酸中心多则更有利于生成丙烯。

FCC催化剂上金属污染及其钝化机理

以有害金属对裂化催化剂的污染为基础,分析了镍、钒、铁、钠、钙对分子筛孔结构、酸性的作用以及对催化剂活性、选择性的影响,探讨了金属钝化剂与有害金属的作用、钝化机理和在优化催化剂使用环境、改善产品分布等方面的积极作用,提出了无毒、高效、多功能的金属钝化剂发展方向。

FCC汽油二次裂化增产丙烯过程中主要影响因素的研究

利用提升管中试实验装置,研究了催化汽油二次裂化制丙烯过程中热裂化、氢转移反应的特点和影响因素,给出了不同反应条件对丙烯选择性的影响,考察了丙烯选择性最大点处热裂化反应、氢转移反应的变化。研究结果表明,采用适当的反应温度和剂油比以及缩短反应时间能有效抑制热裂化反应和氢转移反应的发生,提高丙烯的选择性。

FRS全馏分FCC汽油加氢脱硫技术开发及工业应用

抚顺石油化工研究院(FRIPP)开发的FRS全馏分FCC汽油加氢脱硫技术具有大幅度降低催化汽油硫含量和烯烃含量而辛烷值损失较低的特点。在中国石油化工股份有限公司九江分公司0.4Mt/a装置上的工业应用结果表明,FRS技术能够为我国炼油厂生产清洁汽油提供灵活、经济的技术解决方案。

稀土铈改性FCC催化剂及其性能

四川凉山地区的稀土储量位居世界前列,但因其铈含量过高,导致稀土企业链失衡,急需为"过剩"的铈寻求新的应用领域。通过铈改性FCC催化剂的研究,发现当稀土含量较低时铈的稳定作用优于镧,但在铈含量较高时其稳定作用略弱于镧;适量铈改性催化剂的优点是干气少、焦炭收率低、汽油和柴油收率高,但其液化气偏低,其内在原因可能是Ce4+更有利于形成更多的固体强酸。稀土铈可用于制备FCC催化剂,铈改性FCC催化剂更适合于具有更高汽油收率和更低焦炭需求的催化裂化反应过程。

FCC废催化剂细粉合成超细Y型分子筛

以FCC废催化剂细粉为原料,通过向合成体系中引入无机盐、调变碱度和结晶温度,可以控制Y型分子筛的粒径,得到了大比表面积超细Y型分子筛。以减压蜡油(VGO)为原料油,考察了超细Y型分子筛粒径对催化剂催化裂化反应性能的影响。结果表明,合成体系中引入NaCl可以显著降低Y型分子筛的粒径,较高的碱度和较低的合成温度有利于构建超细Y分子筛的骨架结构;减小分子筛的粒径可以提高轻油的选择性和重油转化率,以及催化剂的抗积炭性能;合成的超细分子筛还显示了优良的水热稳定性。

FCC汽油重馏分的催化裂化和热裂化产物组成的研究

以FCC汽油重馏分为原料，分别在惰性石英砂及酸性催化剂上，反应温度为300 -700℃，在小型固定流化床上进行热裂化和催化裂化实验。结果表明，FCC汽油重馏分的热裂化起始反应温度为525℃左右。在催化裂化实验中，当反应温度为300-500℃时，FCC汽油重馏分催化裂化所得的干气100％由单分子裂化反应所产生；525℃时93％的干气由单分子裂化反应产生；550℃时63％的干气由单分子裂化反应产生；反应温度高于600℃时，干气几乎100％由热裂化反应所产生。单分子裂化反应所产生的干气组成中，按体积分数大小的顺序依次为C2H4、CH4、H2和C2H6。而热裂化反应所产生的干气组成中，CH4体积分数最高，约占50％，其次为H2，然后依次为C2H4、C2H6。当反应温度为300～600℃时，FCC汽油重馏分催化裂化所得的液化气80％～100％由催化裂化反应所产生，其主要组成为C3H4、iC4H10和C3H8，而热裂化液化气的主要组分为C3H6、iC4H8和C3H8。