Mn2O3-TiO2-Na2WO4/SiO2+SiC催化剂上微波催化高效甲烷氧化偶联反应OA

Oxidative coupling of methane(OCM)is an important way for the high-value utilization of methane(CH4),but there are still some problems such as insufficient conversion and selectivity under traditional thermal catalysis.Herein,a new Mn2O3-TiO2-Na2WO4/SiO2+SiC microwave catalyst was developed for the oxidative coupling of methane under microwave irradiation.The results indicate that the calcined Mn2O3-TiO2-Na2WO4/SiO2+SiC catalyst is superior to the uncalcined counterpart in performance and the microwave catalytic reaction mode(MCRM)is significantly advantageous to the conventional reaction mode(CRM)for the OCM.For OCM at 700 ℃ in MCRM,the conversion of CH4,the selectivity to C2-C3 hydrocarbons,and the yield of C2-C3 are 26.6％,76.5％and 20.4％,respectively,much superior to the values of 12.3％,61.9％and 7.5％in CRM under identical reaction conditions.That is,microwave irradiation can significantly enhance the yield of C2-C3 for OCM at a lower reaction temperature.The Mn2O3-TiO2-Na2WO4/SiO2+SiC catalyst shows favorable stability at 700 ℃ during the OCM reaction in MCRM for 20 h,with a methane conversion of above 25％and a selectivity of above 76％to C2-C3 hydrocarbons.Further study illustrates that the microwave irradiation can significantly reduce the apparent activation energy to 27.5 kJ/mol,compared with the value of 173 kJ/mol in the conventional mode,promote the free radical coupling and inhibit deep oxidation of OCM products.These results provide a new idea for the efficient conversion of CH4 at a low temperature and for the sustainable development of green chemical industry.