烯烃在催化裂化催化剂上反应机理的初步研究

在自制的微反-色谱装置上，进行了单体烯烃和催化裂化汽油在不同条件下的催化裂化反应实验。对单体烯烃的裂化反应规律和汽油中的烯烃在半再生催化剂和待生催化剂上的催化裂化反应规律进行对比分析。结果表明，单体烯烃反应中，C6及C6以下的烯烃主要发生骨架异构和双键异构反应，氢转移和直接裂化反应发生的较少。C7以上的烯烃95%以上发生转化，高温下直接裂化生成C3、C4，氢转移和异构化比率较大。汽油中的烯烃转化主要集中在C7以上，烯烃之间存在一定的交互作用，单体烯烃的催化裂化反应规律可以初步预测汽油中烯烃的转化。催化剂上的结焦类型对汽油中的烯烃的转化方式没有影响。

Study on the reaction mechanism of olefins on FCC catalyst

With the increasing attentions to global environment, it becomes a new subject to reduce the olefin content in catalytic cracking gasoline, and to increase the content of iso-paraffin and naphthene at the same time.As the mid-product of the FCC process, olefin will undergo various reactions, and its reaction mechanism is quite complex. A series of cracking experiments of pure olefin compounds and FCC gasoline under different reaction conditions have been carried out in the self-made instrument of subminiature reactor-chromatograph united apparatus. The reaction mechanism of pure olefin compounds and that of olefins in gasoline under different conditions were analyzed. In the reactions of pure olefin molecules, the olefins with carbon number less than six mainly isomerize, and no cracking and H-transformation reactions take place. 95 % of olefins with carbon number more than seven directly crack to produce C3, C4 at high reaction temperatures. Compared with the rules of pure olefin compounds cracking, the conversion of olefins in gasoline mainly occurs among olefins with carbon number more than seven, and the content of C5 , C6 olefins in upgraded gasoline is hardly reduced. Though some interactions of olefin compounds in the gasoline upgrading process are observed, the mechanism and rules of pure olefins can be used to predict the conversion of olefins in gasoline. Therefore, under FCC conditions, it is difficult to transform C5, C6 olefins, and this is also the key problem of olefin reduction. Conversions of olefins over spent catalyst and regenerated catalyst with a small quantity of coke deposition were compared. It is found that the route of the conversion of olefins in gasoline is hardly influenced by the type of coke on catalyst.