Highly selective synthesis of tetramethylbenzene from CO2 hydrogenation over ZnZrO/modified-ZSM-11 tandem catalyst

Abstract

Direct hydrogenation of CO₂ into high value − added chemicals and fuels has received great attention in recent years. However, highly selective synthesis of single aromatic product by one − step CO₂ hydrogenation is still a big challenge. Herein, we designed a ZnZrO/modified-ZSM-11 tandem catalyst which realized the selectivity of aromatics in liquid products up to 96 % and the selectivity of tetramethylbenzene(TeMB) in aromatics up to 83 % in the reaction of CO₂ hydrogenation. We found that the organic base TBAOH is more favorable for the generation of uniform mesopores in ZSM-11 compared to TPAOH, thus increasing the selectivity of aromatics and TeMB. In addition, the secondary acid treatment mainly removes the extra − framework Al(EFAl) species produced by the alkali treatment, which significantly increases the relative amount of the strong Brønsted acid, thus facilitating further increase in the selectivity of aromatics and TeMB.