稀土氧化物对甲烷催化氧化的分子束研究

THE MOLECULAR BEAM STUDY OF THE CATALYTIC OXIDATION OF METHANE BY RARE EEATH OXIDES

通过分子束与表面散射实验确定甲烷在Ｌａ２Ｏ３清洁表面是平动能激活吸附，阈值平动能５３．４８ｋＪ／ｍｏｌ．氧在Ｌａ２Ｏ３清洁表面的吸附服从Ａｒｒｈｅｎｉｕｓ方程关系，其脱附峰在９６０Ｋ。甲烷只在吸咐氧的Ｌａ２Ｏ３表面发生催化氧化反应，催化剂样品温度在８００Ｋ以后反应产物ＣＯ２出现，但其关键因素还是ＣＨ４分子的平动能。在阈值平动能以下，样品温度超过８５０Ｋ也无反应产物出现。

The methane molecular beam scattering experiments of La2O3 surface have been made. The adsorption of methane on the clean surface of La2O3 is the translational energy activation adsorption ,its threshold value is 53. 58 kJ/mol. The adsorption of oxygen on the clean surface of La2O3 is suited to the Arrhenius equation ,the desorption peak of oxygen is on 960K. The La2O3 surface coated oxygen can catalyze the oxidative reaction of methane ,its reaction product co_2 appeared above 800K. The key factor of this reaction is the translational energy of methane molecule. No product can be seen below the threshold value of thetranslational energy even though higher than 850K.