反应气中的湿度对Au/Co_3O_4室温催化氧化甲醛的影响

采用共沉淀法制备了Au/Co_3O_4催化剂,通过TG-DSC、XRD、BET、XPS等技术对其进行了表征,并考察了其室温下催化氧化甲醛的性能.结果表明,Au的负载降低了Co3O4催化氧化甲醛的反应温度,在25℃具有60%的催化去除效率(RH 0%,GHSV 80 000 h-1)和100%的CO2选择性;室内环境湿度水平的水汽能显著提高其催化活性,在25℃达到了95%以上的甲醛去除效率(RH 50%,GHSV 80 000 h~(-1))和100%的CO_2选择性,活性持续2 0 h以上未见降低.XPS结果表明,Au在Co_3O_4表面主要以金属单质形式存在,其引入提高了催化剂表面的Oads/Olatt比.原位红外(In situ DRIFTS)分析结果表明,甲酸盐和二氧亚甲基(DOM)是催化反应过程中的主要中间物种,水汽的引入有利于促进甲酸盐的生成、中间产物的氧化分解以及产物的脱附.

Influence of Environmental Humidity on Au/Co3O4 Catalytic property for Formaldehyde Oxidation at Room Temperature

Au/Co3O4 catalyst was prepared by co-precipitation method and applied in the catalytic oxidation of formaldehyde.Au-loading significantly reduced the temperature of formaldehyde oxidation,and 60％ of formaldehyde were removed at room temperature (25 ℃,RH 0％,GHSV 80 000 h-1) with 100％ CO2 selectivity.When moisture was introduced,over 95％ of formaldehyde were oxidized with 100％ CO2 selectivity (25 ℃,RH 50％,GHSV 80 000 h-1),and no activity decrease was observed for more than 20 h.XPS results revealed that Au loaded on Co3O4 was mainly metallic,and its introduction increased surface Oads/Olatt ratio.In sjtu DRIFTS results indicated that formate and dioxymethylene (DOM) were the main intermediates,and the presence of moisture accelerated the formation of the formate species.The results obtained by regulating the reaction conditions revealed that moisture facilitated formaldehyde oxidation and products dissociation.