Direct hydrogenation of CO2 to C4+ isomerized olefins on a K/Fe2N-xGa/ASA bifunctional catalyst

Direct conversion of CO 2 toward isomerized heavy olefins remains a challenge. In this work, Fischer-Tropsch synthesis and light olefins oligomerization were coupled to produce isomerized heavy olefins from CO 2 hydrogenation on a bifunctional K/Fe 2 N- x M/ASA catalyst. A K/Fe 2 N-17.0%Ga/ASA achieved the highest selectivity (47.7%) toward C 4+ heavy olefins, among which the selectivity of isomerized olefins was as high as 32.2%. Ga species did not adsorb light olefins (e.g., ethylene) directly, but they boosted the adsorption of light olefins on ASA support. Besides, the addition of Ga promoted H 2 dissociation to generate Ga-H species, which further transferred onto ASA support to form additional Brønsted acid sites promoting oligomerization reaction that obeyed β-H elimination mechanism via alkoxide intermediates. This work developed not only a unique K/Fe 2 N as Fischer-Tropsch synthesis catalyst, but also an integrated system coupling Fischer-Tropsch synthesis and light olefins oligomerization to achieve high selectivity isomerized heavy olefins synthesis from CO 2 hydrogenation.