催化裂化装置沉降器内结焦的微观结构及其生长过程的分析  

Analysis of microstructures of coke and coking mechanism in the reactors of fluid catalytic cracking units

作　　者：魏耀东[1] 宋健斐[1] 张锴[1] 高岱巍[1] 时铭显[1] 

机构地区：[1]中国石油大学(北京)化工学院,北京102249

出　　处：《燃料化学学报》2005年第4期445-449,共5页Journal of Fuel Chemistry and Technology

基　　金：国家自然科学基金(20476057);国家重点基础研究发展规划(973计划;2004CB217803);中国石油化工总公司基础研究资助项目(X504017)~~

摘　　要：对催化裂化装置(FCCU)沉降器内结焦的微观结构进行分析,结果表明,结焦形态主要有4种,丝状焦、滴状焦、块状焦和颗粒状焦。各种结焦形态的成因机理不同,微观结构及生长过程也不同。丝状焦是由铁、镍金属元素催化烃类气体,以及易生焦物发生脱氢缩合反应,以催化剂颗粒形成结焦中心并逐渐长大形成细丝状焦炭;滴状焦是由稠环芳烃脱氢缩合反应而生成,高沸点未汽化油滴黏附在催化剂颗粒或器壁表面形成“焦核”,即由重芳烃、胶质、沥青质脱氢缩合反应和二烯烃聚合环化反应而生成的;块状焦是高沸点未汽化油滴相互溶解后,再脱氢缩合反应或聚合环化反应而形成的结焦;颗粒状焦是油气在气相中脱氢缩合反应或聚合环化反应形成的微小结焦颗粒相互团聚形成的颗粒簇。催化裂化装置沉降器内的结焦一般是上述几种结焦过程的组合,是催化结焦和非催化结焦过程共同作用的结果。Coke depositions in modem fluid catalytic cracking units （FCCUs） have been found in many parts of the unit, which can form large accumulations in reactors and affect the process performance and more badly, result in a significant safety hazard. Therefore, it is necessary to understand the microstructures of coke and coking process in commercial FCCUs. Coke samples from the FCC reactors in several refineries and their microstructures were analyzed by using both scanning-electron microscope （SEM） and X-ray analysis （EDS） methods. Meanwhile, the coking process was also investigated. The cokes can be divided into four kinds, i. e. filamentous coke, guttate coke, block coke and particle cluster coke, which have different formation mechanisms. The coking process in the FCC reactors is a complicated sequence of catalytic and/or noncatalytic reactions. Some occur in the gas phase and the others on the solid surfaces. The filamentous coke is formed from gaseous hydrocarbons metal-catalyzed reaction in which metal carbides are intermediate compounds catalyzed by iron and nickel. The guttate coke is resulted from the coking of non-volatile tar droplets which are transferred to the solid surfaces. As a result of dehydrogenation and condensation reactions of multi-ring aromatics, resins and asphaltenes and the cyclization and polymerization of olefin and diolefin, the non-volatile droplets are rapidly carbonized and a graphitic coke spheroid is produced. The block coke is formed when the non-volatile droplets are dissolved together and then carbonized. The particle cluster coke is formed by the agglomeration of micro coke particles formed in the gas phase.

关 键 词：催化裂化 沉降器 结焦 微观结构 生长机理 

分 类 号：TQ016[化学工程]