Selective oxidation of methane to formaldehyde over antimony oxide-loaded catalyst

A possibility of antimony oxide as a catalyst for the selective oxidation of methane with oxygen to formaldehyde was investigated. The activity measurement was carried out at an atmospheric pressure and at 873 K, where the homogeneous gas-phase reaction was negligible. Oxidized diamond (O-Dia)-supported antimony oxide catalyst produced 1.3 mmol h−1 g-cat−1 of formaldehyde with a formaldehyde selectivity of 23%. On the other hand, SiO2 supported antimony oxide catalyst exhibited negligible catalytic activity. XRD and UV–vis analyses revealed that α-Sb2O4 was formed on the oxidized diamond while Sb6O13 was formed on SiO2. Selective oxidation of methane to formaldehyde seemed to proceed on α-Sb2O4 with moderate activity and selectivity to formaldehyde, via a redox cycle of α-Sb2O4 and Sb2O4−x. On the other hand, Sb6O13 on SiO2 was stable under the reaction conditions and the selective oxidation occurred only slightly.

Graphical abstractMethane was selectively oxidized to formaldehyde on Sb2O4 loaded oxidized diamond catalyst. Figure optionsDownload full-size imageDownload as PowerPoint slide