Rh promoted In2O3 as a highly active catalyst for CO2 hydrogenation to methanol

Abstract

Synthesis of methanol with high selectivity and productivity through hydrogenation of CO₂ is highly attractive. This work uses a Rh doped In₂O₃ catalyst to achieve a high methanol productivity of 1.0 g_MeOH h⁻¹ g_cat⁻¹ while maintaining the intrinsic high selectivity of pure In₂O₃. Rh facilitated the dissociation of H₂ leading to creation of oxygen vacancies over the In₂O₃ surface. In addition, Rh atoms also participated in the activation of CO₂ to produce formate species with a low activation barrier as evidenced by DFT calculation. Rh species were atomically dispersed in the In₂O₃ matrix and were stable during a long term reaction. Under reaction conditions, the surface Rh atoms were reduced and were stabilized by charge transfer from neighbouring In atoms. Our results show that incorporation of atomic Rh species in In₂O₃ can lead to high methanol productivity by creation of oxygen vacancies as well as Rh centred active sites for CO₂ activation.