Studies on Selective Oxidation of Methane to Methanol over Mo/La-Co-O Catalyst

The La Co O (perovskite type oxide), being selected as catalyst support for its high ability in activation of O 2, was prepared by sol gel method using citric acid. A series of Mo/La Co O catalyst samples with different Mo loading were prepared by wetness impregnation method. The catalytic performance of the catalyst samples in selective oxidation of CH 4 to CH 3OH was tested. The reaction resulted in products CH 3OH, CO and CO 2 over these catalyst samples. With the increase of Mo loading, CH 4 conversion gradually increased and CH 3OH selectivity gave maximum value on 7%Mo/La Co O catalyst. The CH 3OH selectivity of ca 60% and its yield of ca 6 7% were achieved under the conditions of n (CH 4) ∶ n (O 2) ∶ n (N 2) =10∶1∶1, SV=14 4 L/(g·h) , p =4 2 MPa and θ =420 ℃. And the CH 3OH selectivity and yield continuously increased with the increase of reaction temperature on 7%Mo/La Co O catalyst. The properties of the catalyst, such as structure, reducibility, oxidation state of surface ions, surface composition etc , were characterized by using BET, XRD, LRS, H 2 TPR and XPS techniques. The catalyst is mainly composed of LaCoO 3 and Co 3O 4. The molybdena is amorphous and is well dispersed when it is loaded on La Co O. On the other hand, there exists interaction between the loaded Mo and the support La Co O, and thus modifies the properties of the catalyst. With the increase of Mo loading, the reducibility of the catalyst is improved, and the O -/O 2- ratio on the catalyst surface decreases. The reducibility and the O -/O 2- ratio can determine the catalytic performance of Mo/La Co O catalyst in the selective oxidation of CH 4 to CH 3OH. The proper reducibility and proper O -/O 2- ratio of the catalyst can enhance the selectivity and yield of CH 3OH.