沉积钒氧化数对催化裂化催化剂酸性和结构的影响  

EFFECT OF OXIDATION NUMBER OF DEPOSITED VANADIUM ON THE ACID PROPERTIES AND STRUCTURE OF CRACKING CATALYST

作　　者：周岩[1] 龙军[2] 刘宇键[2] 周涵[2] 

机构地区：[1]中国石化催化剂齐鲁分公司,淄博255336 [2]石油化工科学研究院

出　　处：《石油炼制与化工》2008年第1期44-48,共5页Petroleum Processing and Petrochemicals

摘　　要：采用择效活化方法降低催化剂沉积钒氧化数,表征结果显示低氧化数沉积钒催化剂总酸量降低,钒物种熔点提高,催化剂金属中毒得到缓解,裂化活性中心酸强度有所增强。由此认为具有酸性的高氧化数沉积钒对催化剂裂化性能产生负影响,提出"负效酸中心"概念。借助分子模拟技术对钒氧化物在分子筛上的沉积状况进行考察。结果表明,与高氧化数沉积钒相比,低氧化数沉积钒在FAU分子筛孔口及超笼内的沉积位置更接近晶格氧,VO与晶格氧的距离最近。由此认为降低沉积钒的氧化数有利于优化钒在分子筛结构内的沉积位置,改善原料分子在分子筛孔道内的扩散,有助于改善催化剂的活性和选择性,降低焦炭产率。It was shown that the reduction of vanadium oxidation number（V Oxnum）by selective activation treatment could lead to the reduction of catalyst total acid amount, increased the melting point of vanadium deposits and increased the acid strength of active sites. A＂negative acid site＂ suggestion was proposed to explain the negative effect of acidic vanadium deposits with high V Oxnum on the cracking performance of catalyst. The depos status of transition metal oxides, especially vanadium oxide at various oxidation states on FAU zeolite was studied by molecular modeling technique. As compared with vanadium oxide having high V Oxnum,VO deposited inside or at the entrance of the super-cage of FAU zeolite was found to be closed to the framework oxygen atoms. Thus, the reduction of V Oxnum could improve the diffusion of hydrocarbon molecules inside the zeolite channel,resulting in the improvement of catalyst activity and stability,less coke was produced as well.

关 键 词：催化裂化 催化剂 氧化钒 酸性 结构 

分 类 号：TE624.91[石油与天然气工程—油气加工工程] O621.254[理学—有机化学]