CeO2纳米棒支撑骨架孔结构原位负载贵金属及其催化性能研究

In this project, melt-spun Al-Ce ribbons will be prepared through the arc-melting and melt-spinning methods. The ribbons will be dealloyed in alkaline solution and then calcined to fabricate CeO2 nanorod framework with pores structure. The effects of the compositions in the precursor alloys, the concentrations of the dealloying solution and temperature on the physical parameters of the framework with pores structure will be analyzed systematically. One and several noble metals are added into the precursor alloys. The single-effect and multi-effect catalysts in which the noble metals are in situ loaded on the CeO2 nanorod framework are prepared. The influence factors will be studied deeply, including the structural parameter, the size, morphology and distribution of noble metals and the microstructural formation mechanism of composite materials. Subsequently, we will be measured the single-effect and multi-effect catalytic performance of composite materials for catalytic conversion of CO, nitrogen oxides, hydrocarbons and other harmful substances. The dependence of the catalytic performance on the precursor alloy composition and the preparation process will be revealed, and the mechanism is deduced. The reaction kinetic equation during the catalytic process will also be drawn. The precursor alloy composition and the preparation process of composite materials will be optimized to obtain catalyst with the best performance in the above systems. The achievements are not only of great significance for the development of new high-performance, low-cost hazardous gas purification catalysts, improvement of the application value for rare earth elements and saving noble metals, but also to enhance the abilities of air pollution management, reduce governance cost and promote the development of catalytic materials.

本项目将通过熔炼和熔体快淬法制备Al-Ce合金快淬带，在强碱腐蚀液中脱合金后煅烧，制备出CeO2纳米棒支撑骨架孔结构，系统分析前驱合金成分、腐蚀液的浓度和温度对骨架孔结构物理参数的影响。将一种和几种贵金属加入到前驱合金中，制备出CeO2纳米棒支撑骨架孔结构原位负载贵金属单效和多重效果催化剂，深入研究其结构参数、贵金属的形貌、尺寸、分布的影响因素和复合材料微观组织形成原理；测试这些复合材料CO、氮氧化物、碳氢化合物等有害物质的单效和多重效果催化转化性能。揭示催化性能对前驱合金成分、制备工艺的依赖性和机制，得到催化过程的反应动力学方程；优化出上述体系中性能最优的复合材料所对应的前驱合金成分和制备工艺。所得结果不仅对开发新型高性能、低成本的有害气体净化催化剂，提升稀土元素的应用价值和节约贵金属有重要意义，而且对于提升空气污染治理水平，降低治理成本以及促进催化材料的发展都有重要价值。

将CO、甲烷等害气体转化成无害的CO2或水等对于工业的可持续发展和环境保护具有重要意义。本项目采用溶体快淬带脱合金制备了CeO2、Sm2O3纳米棒支撑孔结构、Co2O3、TiO2等纳米多孔金属氧化物原位负载Au、Pt、Pd、Rh等一种或两种贵金属的复合材料，系统分析了不同成分的前驱合金脱合金后贵金属的形态、分布等微观组织特征，测定了产物的比表面积、孔径、孔体积等物理参数，分析了产物中各元素的价态和电子转移特征，测定并深入分析了不同复合材料催化CO、CH4氧化能力及其机制，优化了前驱合金成分、脱合金以及热处理工艺。结果表明，当溶体快淬Al-Ce合金中的Ce含量为8at%时，得到的CeO2纳米棒支撑孔结构具有最佳的结构参数和催化活性；当溶体快淬Al-Ce或Al-Sm合金中添加Au、Pt、Pd、Rh后，贵金属以纳米颗粒的形式原位负载在纳米棒或韧带表面，可使催化氧化CO的温度大幅度降低；特别是当Al92Ce8合金中加入0.5at%的Au、Pt或Pd时，CO转化50%的温度可以降低到30℃以下，而且具有很好的抗中毒性、耐水性和性能稳定性；其中Au对降低转化50%CO的温度能力最强，Pt和Pd对于提升高温催化性能最佳；采用双贵金属添加有效强化了上述效果；当Al-Ce合金中加入0.7 % Rh后，转化99% CH4的温度从约700℃降低到约 400℃；贵金属对Sm2O3的催化性能提升也有相似的作用。分析表明，贵金属与稀土氧化物间的电子传输导致的交互作用是提升复合材料催化性能的主因，贵金属间的电子传输加强了这种交互作用。研究结果还显示，脱合金制备的纳米多孔Co2O3、TiO2等氧化物或与稀土氧化物构成复合材料并负载少量贵金属后，体系具有优异的催化CO转化能力，展示出节约贵金属的良好前景。本项目研究还显示，Al-Ti前驱合金中加入不大于0.05%的Pt、Ag或Pt-Ag时脱结合后，得到的海参状纳米多孔TiO2负载纳米贵金属复合材料水裂解制氢能力显著提升，在新能源领域显示出广泛的应用前景。在本项目的资助下，合计发表（标注51771141基金号）的相关SCI学术论文21篇，申请国家发明专利1项，培养博士研究生5名，硕士研究生1名。