整体式催化剂活性物质抗脱落性能研究

Honeycomb ceramic and metallic monolithic catalysts are universally facing an important problem that the washcoated active materials tend to spall from their monolithic substrates. The spalling of active materials is one of the key factors for preventing industrial application of monolithic catalysts. Monolithic catalysts show a lot of obvious advantages and are more and more widely used in chemical and biochemical processes. However, there is little people paying attention to the mechanical stability of monolithic catalysts, and the basic theoretical knowledge of the failure mechanism of active materials is not reported as yet. Therefore, this project will focus on the mechanical stability of honeycomb ceramic and metallic monolithic catalysts. Experimental examination and theoretical analysis are used to systematically study the spalling process of active materials, to study the relationship between the catalyst structure, material properties and the failure of active materials, to clarify the failure mechanism, and to propose a model which is used to describe the spalling of active materials. In addition, this work will aim to develop laboratorial testing and analyzing methods for studying the spalling resistance and to put forward a related optimum approach to improve the mechanical stability during the preparation of monolithic catalysts. In this project, the simulation experiments of monolithic catalysts in practical use are proposed for the first time. And the thermal cycle shock is, for the first time, applied to test the mechanical stability of monolithic catalysts. The theoretical innovation of the project is to gain a scientific understanding of the spalling resistance of active materials, which can offer the theoretical basis for the preparation and optimization of monolithic catalysts.

活性物质脱落是蜂窝陶瓷基和金属基整体式催化剂普遍面临的一个重要问题，是决定该类催化剂能否工业应用的关键因素之一。整体式催化剂在很多反应中有显著的优势，其应用越来越广泛，但是关于抗脱落性能的研究尚十分薄弱，特别是关于活性物质脱落机制等基础理论认识非常缺乏。本项目拟以蜂窝陶瓷基/金属基整体式催化剂的机械稳定性为研究对象，采用实验研究和理论分析相结合的方法，系统研究活性物质脱落过程，研究整体式催化剂结构特征、材料性质与其抗脱落性能的关系，阐明脱落机理，建立脱落模型，建立抗脱落性能实验室测试与分析的科学方法，提出制备过程整体式催化剂抗脱落性能的优化方案等。项目首次提出整体式催化剂实际应用状况下破坏的模拟实验研究，首次提出抗脱落性能的热循环冲击实验室测试方法等，其成果理论创新主要表现在对整体式催化剂活性物质抗脱落性能形成科学认识，以便为整体式催化剂制备与改性优化提供理论依据。

活性物质脱落是蜂窝陶瓷基和金属基整体式催化剂普遍面临的一个重要问题。本项目针对这一问题，开展了实验与理论研究，获得了基础性认识。. 研究了蜂窝陶瓷基和金属基整体式催化剂的活性物质脱落过程，理论分析了活性物质脱落机制和脱落性能离散性等。首次提出应力诱发的疲劳损伤是活性物质脱落的根源。在应力下，活性层体相缺陷/活性层与基质间界面缺陷处发生应力集中，萌生微裂纹，然后扩展形成宏观裂纹。多个宏观裂纹的交叉、连接，造成了活性物质的脱落。蜂窝陶瓷基整体式催化剂既有界面脱落（活性层与金属基质界面处脱落）又有体相脱落（活性层内部崩裂而脱落），而金属基整体式催化剂仅有界面脱落。另外，各种缺陷的大小、形状和取向的随机化导致脱落过程的随机化以及脱落率数据的离散性。. 实验考察了热冲击过程对整体式催化剂活性物质脱落过程的影响。结果表明，升温、降温速度快慢对活性物质脱落有着显著影响，在实际工业应用中应尽量避免急剧升温和急剧降温过程。考察了蜂窝陶瓷基质/金属基质的预处理、涂敷浆液固含量、添加剂及其加入量、涂敷次数、涂敷后干燥和焙烧条件等制备因素对整体式催化剂机械稳定性的影响，探讨了制备因素的影响机理；并以脱落机制模型为理论依据，分析了控制活性物质脱落的因素，提出优化方案，并赋予抗脱落性能的制备因素的科学解释。此外，数值模拟研究了整体式催化剂测试试样体积和试样个数对抗脱落性能测试结果的影响，确定了想要得到可靠测试结果所需的最小试样体积和最少试样个数，建立了抗脱落性能实验室测试与分析科学方法。. 项目研究成果主要表现在整体式催化剂机械稳定性方面的理论创新，在一定程度上为整体式催化剂的设计和生产提供了理论依据，为整体式催化剂工业应用操作参数的优化提供了可靠指导。项目执行期间，课题组已在AIChE Journal、Industrial & Engineering Chemistry Research、Chemical Engineering Science、Journal of Catalysis等期刊上发表SCI收录论文16篇、EI收录论文2篇，申请国家发明专利5件，授权国家发明专利2件，培养博士研究生2名和硕士研究生5名，圆满完成了原定研究内容以及各项任务指标等。