Abstract
Ethane oxidation was examined over silica supported silicomolybdic acid (SMA) catalysts under conditions described as excellent for partial oxidation to investigate the catalytic activities in the presence of non-catalytic ethane oxidation. When water vapor was absent or limited, SMA was transformed to the α-MoO3 phase, C2H6 conversion was enhanced, and the major products were C2H4 and CO, whereas little HCHO was formed. However, the selectivity for HCHO was improved by the addition of excess water vapor. The acidity of SMA, which was stabilized by water vapor as β-MoO3, might catalyze the scission of the C-C bond, so partial oxidation to HCHO could be promoted in preference to oxidation to CH3CHO. In addition, the formation of the MoO2 phase, which was observed in the co-presence of C2H6 and water vapor, suggested that the lattice oxygen participated in the activation and oxidation of C2H6.
