Impact of the Zeolite Cage Structure on Product Selectivity in CO-assisted Direct Partial Oxidation of Methane over Rh Supported AEI-, CHA-, and AFX-type Zeolites

In this manuscript, we have demonstrated CO-assisted methane conversion into small oxygenates using a Rh catalyst supported on zeolites with AEI-, CHA-, and AFX-type structures (specifically, SSZ-39, SSZ-13, and SSZ-16 zeolites, respectively). Methanol, formic acid, and acetic acid were obtained as the oxygenate products and their selectivities were unique to each of the zeolite framework structures. Smaller cage structures were preferable to produce smaller oxygenates and vice versa. Among them, the AEI-type structure was highly selective (>80%) in the formation of methanol. CO-assisted direct methane conversion was demonstrated with Rh supported cage-type zeolites. The AEI-type zeolite showed high selectivity in methanol production.