<i>y</i>In<sub>2</sub>O<sub>3</sub>-ZnZrO<i>x</i>/Hierarchical ZSM-5 Tandem Catalysts for CO<sub>2</sub> Hydrogenation to Aromatics Rich in Tetramethylbenzene
Bingyu Liu, Yongchao Wang, Ying Xie, Linfei Xiao, Wei Wang, Wei Wu
Abstract
CO 2 conversion to aromatics with high selectivity has great significance for improving the environment and realizing the resource utilization of CO 2 . However, the chemical inertness of CO 2 and the high energy barrier to generate aromatics result in difficulties in catalysts design. Here, we report a tandem catalyst combining indium-promoted composite metal oxides In 2 O 3 -ZnZrO x with hierarchical nanosized ZSM-5 modified by controllable alkali desilication (NZ5-DS) for efficient conversion of CO 2 to aromatics. Indium species were highly dispersed on the surface of ZnZrO x . DFT calculation results demonstrated that the adsorption and activation ability of CO 2 on more abundant oxygen vacancy of indium-modified ZnZrO x was enhanced, as well as the diffusion properties of products in the hierarchical zeolite channels were significantly improved, which promoted conversion of CO 2 to aromatics on the y In 2 O 3 -ZnZrO x /NZ5-DS tandem catalysts. An excellent catalytic performance was obtained over 10In 2 O 3 -ZnZrO x /NZ5-DS with the closest proximity of metal sites and acid sites. A high aromatics selectivity of 92.1% was reached at a CO 2 conversion of 22.4%, and the selectivity for tetramethylbenzenes was as high as 66.3%. The selectivity of undesirable CO was reduced to 11.0% due to inhibition of reverse water gas shift (RWGS) reaction. This catalyst system has potential applications in the conversion of CO 2 to produce tetramethylbenzenes.