Spatially Resolved Reaction Profiles of CO₂ Hydrogenation to Methanol Using In-Based Catalysts in a Compact Profile Reactor

The compact profile reactor (CPR) design allows for the simultaneous acquisition of species, temperature, and spatially resolved reaction profiles during high-pressure CO₂ hydrogenation to methanol. Indium-based catalysts for CO₂ hydrogenation have attracted significant scientific interest since they are more selective, efficient, and resistant to deactivation compared to the state-of-the-art copper-based catalyst. In this study, the reaction profile of In₂O₃/ZrO₂ catalysts is compared to that of the state-of-the-art Cu/ZnO/Al₂O₃ (CZA) catalyst in a high-pressure CPR. It is demonstrated that the addition of nickel as a promoter significantly enhanced the catalytic activity of pure In₂O₃/ZrO₂. The characterization by H₂ TPR and CO₂ TPD revealed an increased capacity for both hydrogen and CO₂. A detailed comparison and optimization of reaction conditions using Ni-In₂O₃/ZrO₂ as a catalyst are presented. In an optimized experiment, Ni-In₂O₃/ZrO₂ produces 4.90 g_MeOH g_In+Ni^-1 h^-1 at 275 °C, 50 bar, and 63,000 h^-1with a methanol selectivity of 73%. Furthermore, no catalyst deactivation caused by metal leaching or sintering could be observed over 90 h time on stream.