Study Of Alkylation Of Coal-Based Olefins With Benzene And Transalkylation Of Multi-Secbutylbenzenes With Benzene

The alkylation of benzene with the coal-based mixed olefins from the MTO products and transalkylation of multi-secbtylbenzenes (MSBB) with benzene were investigated in a small fixed bed reactor over different zeolites. Process conditions of both alkylation and transalkylation were studied. The adsorption of propylene and butylene on MCM-22zeolite and the reaction mechanism of alkylation of benzene with mixed olefins were studied by in situ IR.High conversion of mixed olefins, high selectivity of the main products and long lifetime were achieved in MCM-22zeolite in comparison with Beta, ZSM-5, HY zeolite. MCM-22was the proper catalyst for the alkylation of benzene with coal-based mixed olefins. And the appropriate conditions of alkylation process over MCM-22catalyst were benzene/mixed olefins molar ratio8, weight hourly space velocity(WHSV) of mixed olefins4h-1and temperature210℃The chemical adsorption of propylene and butylene on MCM-22catalyst was observed by in situ IR. And the adsorption of butylene on MCM-22catalyst was difficult than that of propylene. The reaction mechanism of alkylation of benzene with coal-based mixed olefins may be that positive carbon ions CH3-C+H-CH3, CH3-C+H-CH2-CH3were formed from propylene and butylene and they were reacted with benzene to produce iso-propylbenzene (IPB) and sec-butylbenzene (SBB).Compared with Beta and MCM-22zeolite, USY catalyst showed the best catalytic behaviors in transalkylation of MSBB with benzene. Temperature had a great influence on both the conversion of MSBB and selectivity of SBB. Material composition and WHSV of di-secbutylbenzene (DSBB) had little influence on conversion of DSBB and great influence on conversion of tri-secbutylbenzene (TSBB) and selectivity of SBB. The optimum conditions of transalkylation of MSBB with benzene over USY catalyst were:benzene/DSBB mole ratio16, WHSV of DSBB1.4h’1, temperature240℃and pressure3MPa. Under such conditions, the conversion of DSBB, TSBB and selectivity of SBB were87.7%,19.3%,91.4%, respectively.