稀土氧化物对甲烷在Li-碱土金属氧化物催化剂上氧化偶联反应的影响

EFFECT OF RARE EARTH OXIDES ON CATALYTIC OXIDATIVE COUPLING OF METHANE ON Li-ALKALINE EARTH OXIDE

在Li—碱土金属氧化物催化剂的基础上研究了分别添加稀土氧化物(La,Ce,Pr,Nd,Sm)对甲烷氧化偶联反应的影响。结果表明:稀土氧化物的添加有助于提高C_2的选择性,其原因可能是稀土有利于甲基自由基的稳定。

The catalytic activities of different alkaline-earth oxides for methane coupling were compared. The effect of dosing with alkali oxides was also studied. Among the catalysts studied,only Li-CaO exhibited good conversion and hydrocarbon yield. For alkali metal doped magnesia, 5w% Li was optimal for selectivity to hydrocarbons. It was found that although the addition of Li resulted in a decrease in methane conversion, the selectivity for hydrocarbon formation increased significantly. The addition of rate earth metal oxide led to the shortening of induction period and the increase in C_2 selectivity. The effect of temperature on methane coupling was investigated in the range of 893-973K. It was found that the yield of C_2 and ethylene increased with the increase of temperature, while the yield of ethane kept unchanged.