Alkylation of benzene using CO and H over ZnZrO/ZSM-5: the effect of Y doping

The increase in the CO 2 concentration in the atmosphere has caused a serious global climate problem. Aromatics are important intermediates in chemical production, and by utilizing CO 2 in aromatic synthesis not only the effective utilization of CO 2 can be realized, but also carbon emission reduction can be effectively achieved. Herein, a bifunctional catalyst prepared by physically mixing Y-doped ZnZrO x metal oxide with the zeolite ZSM-5 was applied to the synthesis of toluene and xylene by the alkylation of benzene using CO 2 and H 2 . The bifunctional catalyst Y0.1/ZSM-5 showed the best reaction performance. 17.3% conversion of CO 2 , 30.8% conversion of benzene, and 71.6% selectivity of toluene and xylene were achieved. And 96.8% of the liquid-phase products were toluene and xylene. Based on the CO 2 -TPD, H 2 -D 2 exchange, H 2 -TPR, EPR, XPS, and in situ DRIFTS results, a small amount of Y doping can effectively increase more oxygen vacancies on the surface of ZnZrO x to promote CO 2 adsorption and activation. The activation of hydrogen was enhanced resulting from Y-Zn interactions. In the reaction pathway, Y doping accelerated the conversion of CO 2 to HCOO* species to promote the reaction process, allowing more methanol to participate in the benzene alkylation reaction and further improving the CO 2 and benzene conversion. Y doping simultaneously increases the CO 2 and H 2 activation of ZnZrO x .