(544ca) Single Rhodium and Palladium Atoms Anchored in Micropores for Transformation of Methane to Acetic Acid and Methanol Under Mild Condition

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 Rh₁O_m anchored in microporous aluminosilicates in solution at 150C or lower. The activity of these singly dispersed precious metal sites for production of organic oxygenates can reach about 0.10 acetic acid molecules on a Rh₁O_n site per second at 150C 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 of CH₄ is activated by Rh₁O₅ anchored on wall of the micropores; the formed CH₃ couples with COOH species to form the first acetic acid, generating a terminal oxo structure (Rh=O). The Rh=O activates C-H of the second CH₄ molecule, forming CH₃ which then couples with adsorbed CO to form acetyl intermediate. The acetyl couples with adsorbed HO group, forming the second acetic acid molecule. I will also discuss the oxidation of methane to methanol on Pd₁O₄ sites in aqueous solution under a mild condition.