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

The diffusion of aromatics in pores has a great influenceon thedistribution of light aromatics and the stability of zeolites, andthe aromatics selectivity is related to the acidity of the zeolite.Here, the HZSM-5 zeolite, rich in a mesoporous structure and suitableacidity, was manufactured by hydrothermal crystallization in the presenceof a NaOH/TPAOH mixed solution. Because the mesoporous structure ofthe HZSM-5 zeolite facilitates the diffusion of reactants and products,it can regulate the distribution of light aromatics in total aromaticsand attenuate coke deposition. Meanwhile, the treated HZSM-5 zeolitecan adjust the acidity to enhance the aromatics selectivity. The reasonabledesign of zeolites with abundant mesopores and suitable acidity providesa new clue for directly converting syngas to light aromatics. Throughcatalytic performance testing, we obtained 46.89% aromatics selectivityand 55.86% light aromatics in total aromatics at 94.86% CO conversionover mesoporous HZSM-5. Furthermore, the modified mesoporous HZSM-5zeolite with Ce could tune the acidity to promote the aromatics selectivityto 51.33%, maintaining 46.77% light aromatics in total aromatics andhigh catalytic stability in the meanwhile.