钴铈复合氧化物在催化氧化中吸附氧的EPR研究

以溶胶-凝胶法制备了钴、铈及其复合氧化物,考察了其对对甲酚催化氧化的性能,复合氧化物表现出优良的活性和选择性.用EPR方法对3个催化剂样品表面吸附氧及其在可控气氛下与对甲酚的作用进行了研究,实验表明,O₂^-可能为活性氧物种,其吸附量及配位环境可与催化活性和选择性相关联。

EPR STUDY OF THE OXYGEN ADSORBED ON COBALT CERIUM MIXED OXIDES IN CATALYTIC OXIDATION

Co304, Ce02 and Cobalt cerium mixed oxides catalysts were prepared by sol-gel method. Theproperties of the catalysts used for catalytic oxidation of p-cresol to achieve selectivity p - hydroxyben-zaldhyde were investigated. It's concluded that the activity and the selectivity of Cobalt cerium mixedoxide is the best. By using electron paramagentic resonance (EPR) method, the oxygen adsorbedor desorbed on three catalysts, and the action contacted with p-cresol in controlled - atmospherehave been investigated respectively. The EPR results confirm that a signal with 3 - g values (2.003- 2.048) comes from the species of surface adsorbing oxygen, and that they can be assigned to superoxidespecies 02 chemisorbed on the samples. The species 02 is the catalytic active one. Its concentra-tion and complex state correlate with the catalytic oxidation activity and the selectivity of the catalysts.