Influence of different Ga species in MWW zeolite bifunctional catalysts on the ethane dehydrogenation and dehydroaromatization in the absence and presence of CO2

Ga-loaded MWW zeolite catalysts with MWW topology was synthesized by atom-planting through dehydrochlorination of deborated ERB-1 and hydroxyl groups in GaCl3, and further loaded with Pt by ion exchange method for ethane direct dehydrogenation (EDH) and CO2 oxidative dehydrogenation (CO2-ODH) of ethane. The atom-planting introduced GaCl3 generated zeolite framework Si(OH)Ga, extra-framework Ga-OH species and Ga2O3 in synthesized catalysts. And the extra-framework Ga-OH species showed higher ethane dehydrogenation activity compared with the Ga2O3 species, while the Bro center dot nsted acid sites of framework Si(OH)Ga species could further convert the pruduced ethylene to aromatics. The Ga-OH species prepared by atom-planting generate [GaH]2+ and [GaH2]+ during CO2-ODH reaction, which have better ability to activate CO2 and has good activity for reverse water gas shift reaction as tandem reaction to promote the ethane dehydrogenation. The electron transfer between Pt and Ga2O3 made the Pt-Ga bimetallic catalyst show good dehydrogenation activity and stability in the EDH and CO2-ODH reactions.