Selective conversion of CO₂ to isobutane-enriched C₄ alkanes over InZrO_x-Beta composite catalyst

Direct conversion of CO₂ to a single specific hydrocarbon with high selectivity is extremely attractive but very challenging. Herein, by employing an InZrO_x-Beta composite catalyst in the CO₂ hydrogenation, a high selectivity of 53.4% to butane is achieved in hydrocarbons (CO free) under 315 °C and 3.0 MPa, at a CO₂ conversion of 20.4%. Various characterizations and DFT calculation reveal that the generation of methanol-related intermediates by CO₂ hydrogenation is closely related to the surface oxygen vacancies of InZrO_x, which can be tuned through modulating the preparation methods. In contrast, the three-dimensional 12-ring channels of H-Beta conduces to forming higher methylbenzenes and methylnaphthalenes containing isopropyl side-chain, which favors the transformation of methanol-related intermediates to butane through alkyl side-chain elimination and subsequent methylation and hydrogenation. Moreover, the catalytic stability of InZrO_x-Beta in the CO₂ hydrogenation is considerably improved by a surface silica protection strategy which can effectively inhibit the indium migration.