不同方法制备的铟催化剂选择性还原NO

不同负载量的In/Al₂O₃催化剂分别以浸渍法、共沉淀法和溶胶-凝胶法制得,对比评价了不同方法制备的样品在富氧条件下以丙烯为还原剂,选择性催化还原NO的活性,考察了氧气浓度、H₂O对活性的影响.研究表明,铟催化剂有较高的去除NO活性,制备方法对催化剂活性具有显著影响.其中,溶胶-凝胶法和共沉淀法最高活性都可达90%左右;而浸渍法样品的活性较差,最高转化率不到60%.氧气浓度对NOx最高转化率及其相应反应温度均有重要影响.随着O2浓度的提高,最高活性对应的反应温度降低.反应气氛中H₂O的加入使铟催化剂活性大幅降低.铟与其他多种金属活性组分相比,一个突出的不同表现是,3种方法各自的最佳负载量相差不大.

Selective Reduction of NO over Indium Catalysts Prepared by Different Methods

Alumina-supported indium catalysts with different metal loadings were prepared by various methods including impregnation, co-precipitation and sol-gel. Activity tests were carried out on the selective catalytic reduction (SCR) of NO by propene in excess O2 over the catalysts. And the effects of oxygen concentration in reaction gas feed on catalytic activities were examined. The results show that In/Al2O3 catalysts possess high deNO2 activity, and the preparation methods have obvious effects on catalytic activities. The catalysts prepared by co-precipitation or sol-gel method exhibited high NO, conversion to N2 about 90%; the impregnation samples have poor activities, the highest conversion rate not exceeding 60%. The O2 concentration in gas feed has significant effects on the highest conversion rates of NOx reduction and the corresponding reaction temperatures. Along with the increasing of O2 concentration, the temperatures mentioned above declined. The introduction of water into the gas feed depressed greatly the deNO2 activities of In/Al2O3 catalysts. Compared to many other metals as active components of deNOx catalysts, indium has a prominent different behavior that the respective best metal loadings of the catalysts prepared by these three diverse preparation methods have little difference, being all around 1% to approximately 2%.