Construction of HZSM-5 with a Mesoporous Structure and Suitable Acidity: Application in Catalytic Syngas Conversion to Light Aromatics over Na–FeMn/HZSM-5 Zeolite

Abstract

The diffusion of aromatics in pores has a great influence on the distribution of light aromatics and the stability of zeolites, and the aromatics selectivity is related to the acidity of the zeolite. Here, the HZSM-5 zeolite, rich in a mesoporous structure and suitable acidity, was manufactured by hydrothermal crystallization in the presence of a NaOH/TPAOH mixed solution. Because the mesoporous structure of the HZSM-5 zeolite facilitates the diffusion of reactants and products, it can regulate the distribution of light aromatics in total aromatics and attenuate coke deposition. Meanwhile, the treated HZSM-5 zeolite can adjust the acidity to enhance the aromatics selectivity. The reasonable design of zeolites with abundant mesopores and suitable acidity provides a new clue for directly converting syngas to light aromatics. Through catalytic performance testing, we obtained 46.89% aromatics selectivity and 55.86% light aromatics in total aromatics at 94.86% CO conversion over mesoporous HZSM-5. Furthermore, the modified mesoporous HZSM-5 zeolite with Ce could tune the acidity to promote the aromatics selectivity to 51.33%, maintaining 46.77% light aromatics in total aromatics and high catalytic stability in the meanwhile.