Abstract
When the formation of formaldehyde takes place according to the homogeneous gas phase catalytic oxidation under atmospheric pressure, we found, the oxides of nitrogen exhibit the best catalytic effect among several gaseous catalysts and by comparing catalytic activities of nitric acid, nitrogen dioxide and nitrogen oxide, we could determined the optimum reaction condition for the oxidation of methane and proposed the mechanism of the catalytic action by the analyzing it from the standpoint of kinetics. Using the nitrogen oxide catalyst, the optimum conditions for the formaldehyde form-ation by the catalytic oxidation of methane are the reaction temperature of 600 °C, the Concentration of catalyst of 1-3% (mol), the concnteration of oxygen of 10% (mol), and the 600 °C, the concentration of contact time of 0.1-0.3 sec., where methane must be kept always excess to oxygen.Judging from the data on the rate of the oxidation reaction and the formaldehyde concentration in the reacted gas, the catalytic activities seem to decrease in the order of nitric acid, nitrogen dioxide and nitrogen oxide. On the formentioned condition and using nitric acid catalyst, we obtained 60-70%as oxygen conversion, 1.6-2.3%as formaldehyde concentration in the reacted gas mixture and 25-30%formaldehyde yield referred to the reacted methane.
