Carbon dioxide assisted toluene side-chain alkylation with methanol over Cs-X zeolite catalyst

摘要

Zeolite Cs-X is an acknowledged representative basic catalyst useful for side-chain alkylation of toluene with methanol. In spite of numerous investigations, still there has been long lasting challenge for achieving high selectivity for side-chain alkylated products rather than ring alkylated products. In an effort to improve the yields of side-chain alkylated products, CO2 was introduced during the toluene side-chain alkylation with methanol at 425 degrees C over Cs loaded faujasite catalyst. The CO2 addition facilitated in removing the formed hydrogen by reverse water-gas shift reaction and enhanced the product yield. Interestingly, CO2 addition helped in obtaining higher yields of side-chain alkylation products including styrene/ethylbenzene and alpha-methylstyrene/isopropylbenzene. The CO2 introduction resulted in less H-2 formation in the product stream during the reaction. Mesoporosity was also introduced to the zeolite X to improve the activity and product selectivity.