A method wherein a sour natural gas stream can be treated to produce primarily carbon monoxide from methane, and the carbon monoxide and hydrogensulfide are reacted to produce methyl mercaptans, (primarily methanethiol (CH.sub.3 SH) and a small amount of dimethyl sulfide (CH.sub.3 SCH.sub.3)). The methyl mercaptans preferably are passed in contact with a catalyst comprising a supported metal oxide or a bulk metal oxide in the presence of an oxidizing agent and for a time sufficient to convert at least a portion of the methyl mercaptan to formaldehyde (CH.sub.2 O), and sulfur dioxide (SO.sub.2).

A method wherein a methanol-containing gas stream is passed in contact with a catalyst comprising a supported or unsupported bulk vanadate catalyst in the presence of an oxidizing agent for a time sufficient to convert at least a portion of the methanol to formaldehyde (CH.sub.2O).

Catalytic processes have been developed for direct ambient air oxidative conversion of hydrocarbons to aldehydes and unsaturated alcohols. Aliphatic hydrocarbons including methane, hexanes, octanes, decanes, gasoline, diesel fuel, oils, solvents and other organic compounds have been oxidized by this catalytic process. The catalysts are based on molecular strings of di-, tri- and/or poly-groups of transition metal complexes. Laboratory results have demonstrated [iron(II)].sub.2, [manganese(II)].sub.2 and related families of catalysts to be effective for ambient air direct oxidative conversion of hydrocarbons to products in high yields at room temperature and above, while [cobalt(II)].sub.3 was effective for air oxidative conversion of methane to formaldehyde and for other gaseous hydrocarbons to their corresponding aldehydes at elevated temperatures.