The role of K in tuning oxidative dehydrogenation of ethane with CO2 to be selective toward ethylene

Catalytic stability and ethylene selectivity were significantly improved through adding K into Cr-based catalysts in oxidative dehydrogenation of ethane with CO2. A series of K promoted Cr catalysts with different K loading were prepared by impregnation method using Ce-Zr solid solution as support. The porosity, crystalline phase, surface chemical state, lattice oxygen property, redox, basicity etc. were investigated, and the results showed that high content of K would enrich surface Cr6+ and O species through the formation of K2CrO4/K2Cr2O7, which further improved the surface basicity. All of these factors acting to conversion and selectivity should be well coordinated to obtain a good productivity of ethylene. The introduction of K helped the desorption of ethylene from active sites and stabilized the reaction within times on stream of 50 h. The introduction of surface K species suppressed the dry reforming but promoted the selective oxidation to produce ethylene.