Partial oxidation of ethane over silica-supported alkali metal molybdate catalysts

Abstract

The partial oxidation of ethane has been investigated on silica-supported M 2MoO 4 catalysts ( M  Li, Na, K, Rb, Cs) in a fixed-bed continuous-flow reactor at 770–823 K using N 2O as oxidant. Additional measurements included pulse experiments, temperature-programmed reduction of the catalysts, and a study of the catalytic decomposition of N 2O and C 2H 5OH. The numbers of acidic and basic sites have also been determined. Temperature-programmed reduction of the alkali metal molybdates showed that the onset temperature of the reduction decreased from Li to Cs, while the extent of the reduction increased in this sequence. The main products of the oxidation reaction were ethylene, acetaldehyde, CO, and CO 2. Small amounts of CH 4 and C 2H 5OH were also identified. The ethane conversion and the rate of the C 2H 4 and CH 3CHO formation all increased from Li to Cs. Detailed kinetic measurements were carried out on K 2MoO 4/SiO 2. The activation energy of the ethane consumption was 71 kJ/mol. A possible mechanism for the oxidation reaction is discussed.