CATALYTIC PERFORMANCES OF BINARY METAL OXIDES IN METHANE COUPLING WITH CARBON DIOXIDE

摘要

All of binary oxide catalysts comprising alkaline earth metal (Ca, Sr, or Ba) and Mn show synergistic effects on formation of C_2 hydrocarbons in CH_4 coupling with CO_2. Although C_2 selectivity is higher at a larger partial pressure of CO_2 with the Ca-Mn, it is less dependent on the pressure with the Sr-Mn and Ba-Mn and as high as 50 - 80 % in its whole range. The results observed here suggest that chemisorbed CO_2 plays a crucial role in C_2 formation with the Ca-Mn, whereas MMnO_(2.5) activates CH_4 to provide CH_3. radicals with the Sr-Mn and Ba-Mn.