The slow combustion of methane

The slow combustion of methane was studied nearly thirty years ago by W. A. Bone and R. V. Wheeler, who showed (i) that 2CH4 + O2 mixtures react at temperatures between 300 and 400° C. and pressures of 2 to 2⋅3 atmospheres in borosilicate glass tubes with enormously greater velocities than do 2H2 + O2 or moist 2CO + O2 mixtures under similar conditions, and yield CO2 , CO and H2 O without any liberation of either carbon or hydrogen, and (ii) that when CH4 + O2 mixtures were continuously circulated at between 600 and 350 mm. pressure in a closed system comprising a “reaction tube” packed with fragments of porous porcelain and maintained at temperatures between 450° and 500° C., large quantities of formaldehyde (equivalent to between 13 and 20 per cent. of the methane burnt) could be isolated from the products. Such results, together with others on the slow combustion of ethane, ethylene and acetylene, led to the process being formulated as essentially one of successive stages of hydroxylation, thus:—