铈基氧化物催化剂界生相的构建及其根系效应研究

The thermal stability of ceria-based oxide catalyst is one of the most important issues in environmental catalysis. In our previous studies on supported ceria-based oxide catalysts, an interlayer phase would be formed in the interface between carrier oxide and solid solution. This new phase significantly enhances the thermal stability of catalyst. However, the interface area is low for the catalysts prepared by a traditional impregnation technology, and therefore the interlayer phase can not be effectively controlled, which usually results in low activity. This proposal introduces a novel preparation method, and the structure of supported catalyst is expected to be transformed into “nano architecture”, “three-dimensional nanospatial distribution” and “ mespoporous core-shell nanocatalysts” in order to increase the contact area between solid solution and carrier. As a result, the synthesis of the interlayer phase can be controlled and adjusted effectively. Our research work will focus on the formation mechanism of interlayer phase and its surface/interface physical-chemistry effect. The performance of these catalysts on catalytic combustion of VOCs and soot will be investigated. Quantitative matching relationship between carrier metal oxide species and solid solution will be explored. Some ceria-based solid solution catalysts with high activity and thermal stability will be developed. The research results will broaden insight into designing of solid catalysts, and provide a positive guidance in modification, optimization and innovation for preparation of rare oxide catalysts.

构建兼具高活性和热稳定性铈基氧化物催化剂一直是催化工作者追求的目标。申请人前期研究发现，铈基氧化物与载体界面之间可形成界生相，这种新相不仅能稳定活性结构，而且能显著增强其氧化-还原能力。但传统制备技术无法控制铈基氧化物原子向载体定向迁移，限制了界生相生成能力。本项目提出两种创新的制备技术，把负载型氧化物催化剂从传统“负载型”变为“纳米建筑体”和“介孔载体限域”的体相结构，使铈基氧化物和载体充分接触，引导原子向载体晶格定向热迁移，从而有效构建和调控界生相化学组成、微观结构和生成限度。项目重点研究界生相生成机理和表面/界面物理化学效应，以及对催化燃烧VOCs和Soot的催化作用效应，探索载体氧化物种类与铈基氧化物的量化匹配关系，从而指导研制几种具有高活性和热稳定性的铈基氧化物催化剂。本项研究的基础成果在拓宽固体催化剂设计思路，探索稀土氧化物催化剂的改造、优化和创新途径方面可产生积极指导作用。

构建兼具高活性和热稳定性铈基氧化物催化剂一直是催化工作者追求的目标。项目通过溶胶-凝胶和机械研磨法实现了复合氧化物催化剂从传统“负载型”变为“纳米建筑体”制备，使铈基氧化物和异质氧化物体相充分接触，成功构建了完整的铈基固溶体结构，建立了铈基氧化物氧传输通道（OI↔OII→OIII）和活性之间的关系，提出了离子界面支撑和阻隔机制是稳定铈基缺陷活性结构的关键因素，其中Ce-Pr氧化物纳米建筑体表现出最为优异的碳烟燃烧活性和热稳定性。与此同时，项目深入研究了各种载体与铈基氧化物的界面效应，发现了ZrO2和Al2O3具有正向界面效应，可以同时提高活性和热稳定性；而SiO2则为负向效应，会导致铈基氧化物失活。为进一步减少界面效应的影响，提高铈基氧化物本征活性，项目成功构建了完整的铈基复合氧化物催化剂纳米溶胶喷剂，创造新地提出了一条可在任意载体表面喷洒制备的整体结构催化剂的制备路线，可迅速实现工业放大生产和失活催化剂的再生。通过该项基金的资助，发表了9篇学术论文，其中被SCI/EI收录9篇，申请了发明专利4项，培养研究生4名，项目研究成果已经实现了产业化，并在工业应用中推广使用。