Cu–Mg synergy enhanced synthesis of methyl formate over noble metal-free heterogeneous catalyst systems

Abstract

To address the challenges associated with storage and transportation of hydrogen, Liquid Organic Hydrogen Carriers (LOHCs) like methyl formate (MF) offer a promising and sustainable solution for storing hydrogen (8.4% wt) under ambient conditions. The conversion of anthropogenic CO₂ to MF in the presence of methanol, under base-free conditions, is attracting significant research attention, as it not only helps to limit the atmospheric CO₂ but also produces MF as an efficient LOHC. In this study, a supported Cu nanocatalyst was synthesized, demonstrating notable activity for CO₂ hydrogenation to MF, achieving a CO₂ conversion of 14.01%, a turnover frequency (TOF) of 186 h⁻¹, and selectivity greater than 99%. These results represent the highest performance reported among noble-metal-free catalyst systems. The Cu–Mg synergy enhanced catalytic activity was thoroughly investigated in the quest for improved activity. Comprehensive characterization studies were conducted to elucidate the structure–activity relationship, and the catalyst exhibited consistent performance in recycling and long-term experiments. Additionally, a plausible reaction mechanism for the catalytic process has been proposed.