Single rhodium atoms anchored in micropores for efficient transformation of methane under mild conditions

Abstract

Catalytic transformation of CH₄ under a mild condition is significant for efficient utilization of shale gas under the circumstance of switching raw materials of chemical industries to shale gas. Here, we report the transformation of CH₄ to acetic acid and methanol through coupling of CH₄, CO and O₂ on single-site Rh₁O₅ anchored in microporous aluminosilicates in solution at ≤150 °C. The activity of these singly dispersed precious metal sites for production of organic oxygenates can reach about 0.10 acetic acid molecules on a Rh₁O₅ site per second at 150 °C with a selectivity of ~70% for production of acetic acid. It is higher than the activity of free Rh cations by >1000 times. Computational studies suggest that the first C-H bond of CH₄ is activated by Rh₁O₅ anchored on the wall of micropores of ZSM-5; the formed CH₃ then couples with CO and OH, to produce acetic acid over a low activation barrier.