Enhanced catalytic performance of hierarchical Zn/ZSM-5 with balanced acidities synthesized utilizing ZIF-14 as porogen and Zn source in methanol to aromatics

A series of Zn loaded ZSM-5 (Zn/ZSM-5) zeolites were prepared utilizing either Zn(NO3)2 or Zn-based MOFs (ZIF-61, ZIF-8 and ZIF-14) as Zn sources to explore their effects on the catalysts’ physiochemical properties through characterizations and simulations. Results revealed that hierarchical structures containing meso- to macro- pores of 10 ∼ 80 nm aside from the intrinsic micropores were constructed profiting from the use of Zn-based MOFs. On the other side, lager proportions of medium acid and Lewis acid sites were generated by more Zn(OH)+, whose content was proven to be inextricably linked to the binding energy between Zn and ligand as well as local charge valence state of Zn. Benefitting from hierarchical structures and balanced acidities, Zn/Z5(ZIF-14) employing ZIF-14 as Zn source demonstrated higher aromatic selectivity and longer catalyst lifetime (50.9 % and 26 h) than the microporous counterpart synthesized from zinc nitrate hexahydrate (42.1 % and 20 h) in methanol to aromatics (MTA) reaction.