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

Abstract

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, SiO 2 supported antimony oxide catalyst exhibited negligible catalytic activity. XRD and UV–vis analyses revealed that α-Sb 2O 4 was formed on the oxidized diamond while Sb 6O 13 was formed on SiO 2. Selective oxidation of methane to formaldehyde seemed to proceed on α-Sb 2O 4 with moderate activity and selectivity to formaldehyde, via a redox cycle of α-Sb 2O 4 and Sb 2O 4−x. On the other hand, Sb 6O 13 on SiO 2 was stable under the reaction conditions and the selective oxidation occurred only slightly.