Development of Highly Active Catalysts for Low-Temperature CO2 Hydrogenation to Methanol Using a Machine Learning Approach

Abstract

The conversion of CO₂ into methanol through hydrogenation represents a promising approach for the utilization of CO₂ and sustainable chemical production. However, current industrial methods rely on copper-based catalysts, which exhibit low CO₂ conversion and limited methanol yields and require high temperatures and pressures. In this study, we utilized a machine-learning (ML) approach to develop low-temperature CO₂ hydrogenation catalysts. By employing iterative ML model predictions and experimental validation in batch reactors, we screened 580 distinct catalysts and identified 33 catalysts that outperformed the previously reported highly active catalyst (Pt(3)/Mo(20)/TiO₂). The best catalyst, Pt(5)/Mo(8)-Re(1)-W(0.7)/TiO₂, exhibited a methanol production rate of 1.46 mmol g^-1 h^-1 in a batch reactor and a high production rate of 1.8 mmol g^-1 h^-1 in a flow reactor at 150 °C under 4 MPa (H₂/CO₂ = 3). In situ/operando spectroscopic analysis was conducted to elucidate the function of each catalyst component in the methanol synthesis. Detailed analysis revealed that in the best catalyst, Pt primarily facilitated H₂ dissociation, partially reduced Mo oxides were crucial in generating oxygenated species, and the presence of acidic W promoted methanol desorption from the catalyst surface. Re promoted the formate conversion to methanol, thus accelerating the overall methanol formation.