超稳定Au纳米催化剂的构筑及高效催化氧化挥发性有机物的研究

Volatile organic compounds (VOCs) are the key precursors in atmospheric chemical processes, which are harmful to human health due to the production of ozone and secondary particles. The catalytic combustion is the most highly effective technology to remove the VOCs, and the key issue is the choice of catalyst. Supported noble metal catalysts have attracted the extensive attentions due to the high efficiency of VOCs oxidation. Because of the relatively lower cost and greater availability of Au compared to those of the platinum-group metals, supported Au nanocatalysts are superior to the platinum-group metals catalysts. However, the direct applications of the supported Au nanocatalysts are restricted by the weak stablility and high mobility. The current project aims to prepare the ultrastable Au nanocatalysts and increase the VOCs catalytic activity by surface coating-corrosion approach; investigate the effect of the Au solution concentration, surface coating thickness, and calcination temperature on the physicochemical properties, including particle size, distribution and surface defect of Au nanoparticles, and precisely tune the exposure degrees of Au nanoparticles. The catalytic performances of ultrastable Au nanocatalysts are evaluated for the oxidation of VOCs. Based on the results of structure characterization and catalytic performance, we will reveal the relationship between the surface exposure degree of Au nanoparticles and the catalytic performance of VOCs, and elucidate the catalytic mechanism. The research project can provide the foundation for the development of practical ultrastable Au nanocatalysts in the catalytic oxidation of VOCs.

挥发性有机物（VOCs）是大气化学过程中的关键前体物，会生成对人体具有危害的臭氧和二次粒子。催化氧化法是当前消除VOCs最为高效的方法，而其关键在于催化剂的选择，负载贵金属的催化剂由于其催化VOCs高效性受到广泛关注。相比铂族贵金属，低成本和高储量的Au纳米催化剂具有明显的优势，但Au纳米粒子的弱稳定性和高移动性限制了其广泛应用。本项目拟通过表面包覆-刻蚀手段实现Au纳米粒子的超稳定，同时保持催化剂的高VOCs催化活性；系统考察Au溶液浓度、表面包覆层厚度和煅烧温度等对Au纳米粒子尺寸、分布和表面缺陷等物化性质的影响，精准调控Au纳米粒子的暴露程度，评价该催化剂的VOCs催化氧化性能，揭示Au粒子表面暴露位与VOCs催化氧化性能之间的关系，阐明超稳定Au纳米催化剂催化VOCs氧化的作用机制。本项目研究成果可为发展实用型的超稳定Au纳米高效VOCs催化剂奠定基础。

挥发性有机化合物（VOCs）是导致大气环境恶化的关键因素，在臭氧和灰霾的形成和演变过程扮演着重要的作用，因而开发高效治理VOCs的方法迫在眉睫。本项目围绕高效消除VOCs催化剂的制备开展工作，取得如下成果：（1）研究发现原位分解制备的Au/MnO2催化剂对Au具有很好的稳定作用，Au粒子尺寸大约在3 nm，表现出优异的甲苯催化活性和稳定性（T50：202 ºC）；（2）采用酸刻蚀的方法获得Mn2O3催化剂，研究发现酸刻蚀改善了催化剂的还原性及氧移动性，因而有效促进了甲苯催化性能；（3）构筑了Pd/ZrO2催化剂，研究发现Pd粒子与载体ZrO2形成了强的酸碱相互作用，促进Pd电子流向载体，Brønsted酸位点处Pd纳米粒子以氧化态Pd2+存在，增强了表面氧物种活性，甲苯T90温度较正常Pd/ZrO2催化剂降低23 °C；（4）采用掺杂策略，制备具有缺陷的MnxZr1-xO2固溶体，有效提升了催化剂的还原性和晶格氧移动性，证明了氧空位是MnxZr1-xO2催化剂甲苯催化活性提高的关键性原因。本项目研究可以为设计高效降解VOCs催化剂提供重要的科学指导，为改善大气质量提供有力科学和技术支撑。