A Novel Method of 3D Printing High-Loaded Oxide/H-ZSM-5 Catalyst Monoliths for Carbon Dioxide Reduction in Tandem with Propane Dehydrogenation

Oxidative propane dehydrogenation using CO₂ (CO₂-ODHP) is a potential alternative for propylene synthesis. In this study, bifunctional catalysts (V₂O₅, ZrO₂, Cr₂O₃, and Ga₂O₃ doped H-ZSM-5) are synthesized through additive manufacturing for CO₂-ODHP. Characterization and correlation between the various characterizations and the catalytic results indicates that the direct 3D printing of metal oxides alongside H-ZSM-5 can considerably modify the surface properties and bulk oxide phase dispersion, thus leading to enhanced metal oxide reducibility and exceptional CO₂-ODHP performance. Among the metal monoliths, the mixed oxide sample with 5 wt% Cr, 10 wt% V, 10 wt% Zr, 10 wt% Ga and 65 wt% H-ZSM-5 displays the best activity, achieving ≈40% propane conversion, 95% propylene selectivity, and zero benzene/toluene/xylene production. Upon eliminating CO₂, the catalyst monoliths all retain their long-term stability; however, the propane conversions decrease by ≈3% and the propylene selectivities decreased by 5–15%. Nevertheless, all five samples examined here demonstrate exceptional catalytic activities and prolonged stabilities, which are attributed to the even distribution of surface acid sites produced by direct printing of the oxide and zeolite components. Overall, this study presents a novel way of manufacturing bifunctional structured catalysts that exhibit exceptional ODHP performance.