In-situ microwave synthesis of nano-GaZSM-5 bifunctional catalysts with controllable location of active GaO+ species for olefins aromatization

Abstract

Abstract Sustainable development of clean fuels demands a less energy-consuming procedure for the rapid synthesis of high-efficiency catalysts applied in the aromatization of olefins. Here, nanosized ZSM-5 aluminosilicates and GaZSM-5 gallosilicates catalysts were prepared via a seed-induced method by using conventional electric (CE) heating and microwave radiation (MW) heating. The effects of the heating strategy on the morphology, textural property and acidity of the synthesized samples, and also their catalytic performance of 1-hexene aromatization were studied. The results showed that the synergy of Bronsted acid site (BAS) and Lewis acid sites (LAS) provided by active GaO+ species in the catalysts played an important role in 1-hexene aromatization. MW heating can effectively promote the formation of well-dispersed GaO+ species located in the zeolite channels in proximity to BAS, providing higher dehydrogenation activity. Due to the closer spatial proximity and improved synergic effect between BAS and active GaO+ species, the nanosized GaNZ5-MW/MW sample prepared by two-step MW heating in both seed preparation and crystallization exhibited the highest BTX selectivity and the lowest coke-burning activation energy.