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

[Display omitted] • Atom-planting method introduces three Ga species in MWW zeolite. • Ga-OH is more active for ethane dehydrogenation and tandem RWGS reaction. • Pt-Ga bimetallic catalyst is active for RWGS reaction in tandem with the EDH. Ga-loaded MWW zeolite catalysts with MWW topology was synthesized by atom-planting through dehydrochlorination of deborated ERB-1 and hydroxyl groups in GaCl 3 , and further loaded with Pt by ion exchange method for ethane direct dehydrogenation (EDH) and CO 2 oxidative dehydrogenation (CO 2 -ODH) of ethane. The atom-planting introduced GaCl 3 generated zeolite framework Si(OH)Ga, extra-framework Ga-OH species and Ga 2 O 3 in synthesized catalysts. And the extra-framework Ga-OH species showed higher ethane dehydrogenation activity compared with the Ga 2 O 3 species, while the Brönsted 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 [GaH 2 ]+ during CO 2 -ODH reaction, which have better ability to activate CO 2 and has good activity for reverse water gas shift reaction as tandem reaction to promote the ethane dehydrogenation. The electron transfer between Pt and Ga 2 O 3 made the Pt-Ga bimetallic catalyst show good dehydrogenation activity and stability in the EDH and CO 2 -ODH reactions. [ABSTRACT FROM AUTHOR]