THE PROMOTIVE PROPERTIES OF ALKALI-METAL NITRATE MELTS FOR THE PARTIAL OXIDATION OF METHANE TO METHANOL

(Na, K)NO3 melts of various ratios were used as promoters for the part ial oxidation of methane to methanol. Experiments were performed in a flow reactor system under atmospheric pressure and at various temperat ures in the range of 525-600 degrees C. The influence of reaction temp erature, melt composition, and reduced oxygen species on methane conve rsion and methanol selectivity were investigated systematically. The m ajor reaction products were CH3OH, CO, CO2, and trace amounts of C2H6 and C2H4. A methane conversion of 1.8-12.4% and a methanol selectivity of 0.4-14.1% were obtained under these reaction conditions. Binary me lts could achieve higher methanol selectivity than a single melt. The amounts of reduced oxygen species O-2(-) and O-2(2-) were estimated fr om thermochemical data according to the ion equilibrium in molten nitr ates. The promotive effect of nitrate melts was confirmed and the resu lts indicate that superoxide O-2(-) plays an important role for methan ol formation.