Selective oxidation of low-concentration coal mine gas to methanol in oleum over PbSO₄ catalyst

Selective oxidation of low-concentration coal mine gas to methanol was carried out over PbSO₄ catalyst in a concentration of 20% oleum. The effects of reaction temperature, reaction pressure, reaction time and catalyst dosage on the conversion of methane in gas as well as the yield of methanol were studied. What is more, the reaction mechanism of selective oxidation of low-concentration coal mine gas was also investigated. The results showed that the optimal reaction conditions are determined under the reaction temperature of 180°, the reaction pressure of 5MPa, the reaction time of 3h, and the PbSO₄ dosage of 300μmol for selective oxidation of low-concentration coal mine gas to methanol by PbSO₄ catalyst in oleum. Under this technological condition, the conversion ratio of methane in gas is 8.56% while the methanol selectivity is 78.59%. Mechanism research showed that methane in gas is transformed into methyl bisulfate firstly. Besides, the methyl bisulfate is hydrolyzed into methanol. The selective oxidation of low-concentration coal mine gas is following the mechanism of electrophilic substitution. (paper)