稀燃压缩天然气车尾气净化催化剂

Lean-burn CNG vehicle is widely applied owing to its high efficiency and low NOx emission, but the low exhaust temperature, high concentration of vapor and high structural stability of CH4 make the purification of exhaust a great challenge. Considering the stability of lean-burn CNG exhaust purification catalyst and the inhibition of H2O on the catalytic activity, the relationship between the synthesis process of Zirconia-Zinc mixed nano catalytic material and its textural,structural properties, the influences of phase interface characteristic, surface state and high-temperature aging on the textural and structural properties of the materials are to be investigated, accordingly Zirconia-Zinc mixed nano catalytic material with high performance is obtained. In addition, the interaction between active components including Pd, the promoters and the composite nanomaterials, as well as the influence of the synthesis condition on the catalytic performance, will be investigated, and thus developing catalysts with excellent performance. Furthermore, the catalytic performance and anti-aging performance of the lean-burn CNG catalysts, the couple regulation of different reactions, the adsorbed species and the evolution of CH4 and H2O on the catalyst are going to be investigated. The anti-aging regulation and the control mechanism of the stability of the catalysts,the essence of inhibition of H2O on the catalytic performance will be disclosed. Finally, the science and technology of the preparation of the catalytic materials and catalysts for elimination of high performance lean-burn CNG exhaust are developed.

稀燃CNG车具有高的效率和低的NOx排放而被广泛使用，但低的尾气温度，高的水蒸气浓度和CH4高的结构稳定性使尾气净化极具挑战性。针对稀燃CNG尾气净化催化剂的稳定性问题和H2O对催化活性的抑制作用, 研究锆锌复合纳米催化材料的制备过程及其与结构，织构和性能的关系；研究材料的相界面特征，表面状态及高温老化对材料的结构、织构及性能的影响，制备出对稀燃CNG车性能优异的锆锌复合纳米催化材料。研究Pd等活性组分及助剂与锆锌复合纳米材料的相互作用规律及制备条件对催化性能的影响，制备出高性能催化剂。研究稀燃CNG车催化剂的催化性能及抗老化性能，不同类型的反应的耦联规律，CH4和H2O在催化剂上的吸附物种及演变规律，揭示催化剂的抗老化规律及其稳定性控制机制，H2O对催化活性抑制作用的本质及消除或减缓机制，发展稀燃CNG车尾气净化高性能催化材料和催化剂的制备科学和技术。

稀燃压缩天然气（CNG）车具有高的效率和低的NOx排放而被广泛使用，但低的尾气温度、高的水蒸气浓度和CH4高的结构稳定性使尾气净化极具挑战性。氧化锆基载体材料用于制备高性能负载型Pd基催化剂应对上述挑战展示了巨大潜力。尾气净化催化剂需要在高空速尾气气氛条件下的长时间使用过程中保持稳定的结构。因此，氧化锆（ZrO2）基载体材料需具备：稳定的相结构，优良的织构性质和织构稳定性，适当的表面疏水性。提高稀燃CNG车尾气催化净化催化剂稳定性和降低H2O对催化活性的抑制作用的关键是设计和制备高性能的ZrO2基载体材料。. 本项目的主要研究内容是耐高温的相结构稳定的高比表面积ZrO2基材料及高性能负载型Pd基催化剂的制备科学与技术，包括：干燥方式、焙烧温度、助剂添加和表面活性剂添加对ZrO2织构性质、相结构和表面亲疏水性的影响规律研究；ZrO2及其复合材料负载的Pd催化剂性质与性能联系研究；ZrO2基材料负载的Pd-Pt双金属催化剂性能。. 重点研究了ZrO2、Y2O3-ZrO2和SiO2-Y2O3-ZrO2材料及其负载的Pd催化剂或Pd-Pt双金属催化剂。发展了月桂酸辅助沉淀法制备ZrO2基材料制备技术，该方法具有操作简单，重现性好和材料收率高的特点。上述方法制备的Y2O3-ZrO2材料经过800℃、12h焙烧后比表面积和孔容分别达到56m2/g和0.28mL/g，高于文献其他方法制备的同类材料；SiO2-Y2O3-ZrO2材料经过800℃、12h焙烧后比表面积和孔容分别达到115m2/g和0.25mL/g，在950℃、9h焙烧后也能达到71m2/g和0.19mL/g。上述两种材料在700–950℃稳定范围内保持稳定的四方向结构。材料用于催化剂制备，在模拟尾气气氛中，新鲜Pd催化剂（2.51gPd/L）的T50%和T90%分别低至368和404℃，750℃、10h水热老化后T50%和T90%分别为381和420℃；新鲜的Pd-Pt催化剂（Pd/Pt为4，2.48gPd-Pt/L）T50%和T90%分别低至373和411℃，老化后T50%和T90%分别为387和428℃，催化剂活性和水热稳定性优于Pd-Pt/La-Al2O3催化剂（Pd/Pt为4）和先进的商业Pd-Pt催化剂（Pd/Pt为5），具有良好的应用前景。