Exchange reaction of methane with deuterium over solid base catalysts

The exchange reaction of CH4 with D2 was carried out over 13 kinds of metal oxide catalysts. Among them, a series of alkaline earth metal oxides (MgO, CaO, SrO, and BaO) and La2O3 exhibited activity at 300 °C. The variations of the activities of these catalysts as a function of the pretreatment temperature of the catalysts were measured. The pretreatment temperatures to give maximum activity were 700 °C for MgO and CaO prepared from Ca(OH)2, 800 °C for CaO prepared from CaCO3 and for BaO, 1000 °C for SrO, and 650 °C for La2O3. The reaction rate of CH4 + D2 was higher than that of C2H6 + D2 and equal to that of CH4 + CD4 over alkaline earth metal oxides. In the exchange reaction of iso-C4H10 with D2, a methyl H exchanged faster than a methyne H. It is suggested that the reaction of CH4 + D2, as well as C2H6 + D2 and iso-C4H10 + D2, is initiated by the abstraction of an H+ by basic sites on the catalysts.