CO低温氧化高效Pd纳米催化剂的制备与其性能研究

发布时间：2018-05-20 16:04

  本文选题：Pd + CeO_2纳米管　； 参考：《浙江大学》2015年硕士论文

【摘要】：CO氧化反应在多相催化领域具有重要的研究意义和应用前景。CO2激光器、CO气体防毒面具、封闭体系、质子交换膜燃料电池所用到的氢气等都需要脱除CO。同时,CO氧化反应作为研基础究的模型反应,可以用来研究催化剂的结构特征、吸附／脱附性能、氧化还原能力以及反应机理等。贵金属Pd催化剂因其良好的CO低温氧化性能而受到研究者的广泛关注。研究表明,Pd颗粒的结构与分散度、载体的种类和结构以及催化剂的制备方法等因素都会影响其活性。同时,进一步提高纳米Pd催化剂的稳定性,防止金属颗粒在反应中团聚也具有重要的研究价值和意义。本文以Pd纳米颗粒为活性中心,Ce02纳米管为载体,制备得到新颖的具有纳米管结构的负载型Pd纳米催化剂和核壳型Pd纳米催化剂,以期提高Pd纳米催化剂在CO氧化反应中的活性和稳定性,结果表明：1.以Ce02纳米管作为载体制备得到的负载型Pd纳米催化剂在CO氧化中表现出优良的低温活性。在CO与02体积比为1：4,空速为12000 mL·gcat-1·H-2的反应条件下,该催化剂能在100℃实现CO的完全转化。与以普通Ce02作为载体的负载型Pd纳米催化剂相比,该催化剂具有的独特纳米管结构对反应活性更有利。2.以Si02为壳层,包覆负载Pd纳米颗粒的Ce02纳米管,形成核壳型Pd纳米催化剂。该催化剂在CO氧化反应中表现出良好的低温活性,在上述相同的反应条件下,能在140℃实现CO的完全转化。与未包覆Si02壳层的负载型Pd纳米催化剂相比,其活性虽有所下降,但该催化剂表现出更优良的高温稳定性。经过700℃高温老化的稳定性实验后,该催化剂保持结构稳定,Pd纳米颗粒未明显长大,反应活性保持稳定；而负载型Pd纳米催化剂经过相同稳定性实验后,出现明显的Pd纳米颗粒长大和团聚现象,其活性显著下降。
[Abstract]:Co oxidation is of great significance in the field of heterogeneous catalysis. Co gas mask, sealing system and hydrogen used in proton exchange membrane fuel cells need to be removed from CO 2 laser. As a model reaction, CO oxidation reaction can be used to study the structure characteristics, adsorption / desorption performance, redox ability and reaction mechanism of the catalyst. Noble metal PD catalysts have attracted much attention due to their excellent low temperature oxidation of CO. The results show that the structure and dispersion of Pd particles, the type and structure of support, and the preparation method of catalyst will affect their activity. At the same time, it is of great value and significance to improve the stability of nanometer PD catalyst and prevent metal particles from agglomeration in the reaction. In this paper, supported PD nanocatalysts with nanotube structure and core-shell PD nanocatalysts were prepared by using PD nanoparticles as active center and Ce02 nanotubes as support. In order to improve the activity and stability of PD nanometer catalyst in CO oxidation reaction, the results showed that 1: 1. The supported PD nanocatalysts prepared on Ce02 nanotubes showed excellent low temperature activity in CO oxidation. When the volume ratio of CO to O2 is 1: 4 and the space velocity is 12000 mL gcat-1 H-2, the catalyst can realize the complete conversion of CO at 100 鈩，

本文编号：1915327