汽油族组成对汽油催化裂化反应中干气生成的影响

摘要

The effect of gasoline group composition on the formation of dry gas in FCC process is investigated using a fixed-fluidized bed reaction unit and MMC-2 catalyst.Results show that in the FCC process dry gas is mainly produced by catalytic cracking reactions, the percentage of dry gas formed by thermal cracking is low.With the increase of olefin content in gasoline feedstock, the ethylene yield increases significantly, yet the yields of hydrogen, methane and ethane remain almost unchanged.The dry gas components,including hydrogen, methane, ethane and ethylene, are produced during the scissions of penta-coordinated carbonium ions formed by the protonation of paraffin.Ethylene could also be produced by the β-scissions of tri-coordinated primary carbonium ions formed by the protonation of olefin.The ratio of the β-scissions of the primary carbonium ions and the β-scissions of the secondary carbonium ions formed by the isomerization of primary carbonium ions is fixed.%利用小型固定流化床(FFB)装置,采用MMC-2催化剂,考察汽油族组成对汽油催化裂化反应过程中干气生成的影响.结果表明,汽油催化裂化反应过程中干气主要南催化裂化反应产生,热裂化反应产生的干气所占的比例很低.随着汽油原料中烯烃含量的增加,氢气、甲烷和乙烷的产率基本保持不变,乙烯的产率明显增加.烷烃引发反应时形成的五配位正碳离子的裂解反应生成氢气、甲烷、乙烷和乙烯等干气组分.烯烃质子化形成的三配位伯正碳离子可能直接发生β裂解生成乙烯.伯正碳离子直接发生β裂解的反应和先发生异构化生成仲正碳离子再发生β裂解反应的比值基本是固定的.