一步热分解法制备介孔金属复合氧化物及催化氧化挥发性有机物性能研究

Compared with the supported noble metal catalysts, base metal oxides are considered as a kind of cheap material with high efficiency for the removal of volatile organic compounds (VOCs). Compared with bulk materials, porous materials possess larger specific surface area, benefit the diffusion, adsorption and desorption of VOCs, inhibit the catalyst deactivation due to carbon deposition and poisoning, and exhibit much better low-temperature catalytic performance. However, it is hard to directly and rapidly prepare mesoporous metal oxides in a large scale via the traditional methods. In the present study, we try to develop a facile method, i.e. one step thermal decomposition method, for the preparation of mesoporous metal composite oxides. We will investigate the composition and molar ratio of assistant agent (e.g. citric acid, glucose, starch, silk, and activated carbon) and metal precursor (e.g. nitrate or oxalate of Ce, Zr, Cr, Co, Mn, Ni, and Fe), and calcination conditions (e.g. calcination temperature, heating rate, holding time, calcination atmosphere) on the physicochemical properties of the as-obtained mesoporous metal composite oxides. We will evaluate their catalytic performance for the removal of VOCs. On the basis of various characterizations, we will elucidate the “structure-performance” relationship, clarify the involved catalytic mechanisms, and establish the catalytic kinetic models. It is believed that the results obtained in the proposed project will provide a useful guidance on development of highly efficient catalysts for the removal of VOCs.

与负载型贵金属催化剂相比，非贵金属氧化物是有效消除挥发性有机物（VOCs）的低廉催化材料。跟体相材料相比，多孔材料具有更大的比表面积，利于VOCs扩散、吸附和脱附，有效克服积碳和中毒引起的催化剂失活，显著提高低温催化氧化VOCs性能。然而传统方法难以直接、快速、批量制得介孔金属复合氧化物。本项目中我们拟发展一种普适性强的介孔金属复合氧化物的制备方法——一步热分解法。重点研究柠檬酸、葡萄糖、淀粉、蚕丝、活性炭等辅助剂与金属（Ce、Zr、Cr、Co、Mn、Ni、Fe）硝酸盐或草酸盐等前驱体的组成与配比，焙烧条件（焙烧温度、升温速率、保温时间、焙烧气氛）等对介孔金属复合氧化物物化性质的影响；拟评价所得材料消除多组分VOCs的催化氧化性能。基于多种表征结果和催化消除VOCs的性能，研究催化反应机理，揭示催化氧化作用机制，构建性能和物化性质之间的构效关系，为开发高效环境催化材料提供理论和实践指南。

探索了介孔金属氧化物MnO2、NiO、Cr2O3、Co3O4，以及Ce-Co、Ce-Mn、Ce-Cr、Zr-Co、Zr-Mn和Zr-Cr系列介孔金属复合氧化物催化剂的一步直接热分解的制备方法，发现在柠檬酸、葡萄糖和柞蚕丝素粉辅助下的热分解过程，可以得到蠕虫孔状介孔金属（复合）氧化物。受金属无机源的组成及其配比，升温速率、分解气氛等热分解条件的影响，可以制备孔径可调的介孔金属（复合）氧化物或者固溶体复合氧化物。以硬模板氧化硅辅助的纳米复制过程可以制备呈有序孔道结构的介孔材料。研究了催化氧化典型VOCs的性能和水份的影响，估算了反应的活化能。同时对比研究了分解法与水热法、沉淀法和浸渍法的异同。发现Ce和Zr组分的引入可以促进过渡金属氧化物的分散，丰富催化剂吸附氧和晶格氧物种，改善催化剂的氧化还原性能以及物种间的协同作用，利于催化氧化去除VOCs。