Ru基Deacon催化剂烧结机理及抗烧结性能调控机制研究

The Deacon process has been used to recycle chlorine resources, but industrial catalyst was suffered serious sintering problems, resulting in increased costs. In this project, firstly, the RuO2@SiO2 model catalyst was synthesized to discuss the sintering behavior of the Brown motion mechanism and the Ostwald ripening mechanism. And the primary and secondary effect of two mechanisms on RuO2 sintering was revealed. Also, it can identify that which is the diffusion channel for the Ostwald ripening mechanism between the solid surface and gas phase. After that, the comprehensive sintering mechanism for RuO2 would be proposed. Secondly, three interaction forces between the modifier and the RuO2, the modifier and the carrier, and the RuO2 and the carrier were study based on three types of model catalysts. Different types of modifiers are divided according to the acidity, the redox property, and the crystal structure, which is used to clarify their structure-inducing effect, electron-inducing effect, and RuO2 solid solution or complex structure on the stability of RuO2. Meanwhile, it is benefit for getting the general rules of modifiers addition and the control mechanism. Finally, according to above research, the sintering-resistant industrial catalyst were designed and prepared through molding and supporting process. The results of this research will be expected to provide a scientific basis and technical guidance for solving the sintering problem of Ru-based Deacon catalysts, and it is significant for development of industrial catalysts.

Deacon过程实现了氯资源循环利用，然而工业催化剂存在严重的烧结问题，导致成本增加。本项目首先通过RuO2@SiO2模型催化剂的建立，将Brown运动机理和Ostwald熟化机理的烧结行为分开，考察二者影响RuO2烧结的主次关系，并且辨别Ostwald熟化机理是通过固体表面还是气相转移通道进行的，提出完整的RuO2烧结机理。然后，将修饰组分与RuO2、修饰组分与载体、RuO2与载体等三种相互作用力基于三种类型的模型催化剂进行研究。按照酸性、氧化还原性、晶型结构划分不同种类修饰物，揭示修饰物的结构诱导效应、电子诱导效应、以及RuO2固溶体或复合结构对RuO2稳定性的影响，掌握修饰物组分添加的普适性规律和调控机制。最后，根据研究结果和工业催化剂制备工艺特点，设计和制备出新一代抗烧结催化剂。研究成果将为解决Ru基Deacon催化剂的烧结问题提供基础和技术支持，同时对工业催化剂开发具有指导意义。

针对Ru基Deacon催化剂的烧结问题，本项目首先通过RuO2@SiO2核壳结构模型催化剂阐明了RuO2的烧结机理和温度、尺寸、气氛等影响因素，发现2~3nm小尺寸RuO2纳米粒子在200℃即可发生Brown运动机理聚集烧结，300℃以上时发生气相迁移的Ostwald熟化机理烧结。其次，利用酸性氧化物、金红石型氧化物、高熔点氧化物等负载纳米RuO2的模型催化剂，考察这几种类型氧化物对RuO2稳定性的影响规律。结果表明，RuO2的烧结行为受到界面相互作用、比表面积、界面结构的影响，其中界面结构是调控抗烧结性能的最有效途径。再次，r-TiO2载体结构影响研究表明，金属离子体相掺杂的纳米r-TiO2无法抑制烧结。钛酸盐类表面修饰型MOx-TiO2复合氧化物可以抑制载体高温烧结，还可以通过阳离子缺位锚定RuO2颗粒，抑制烧结。溶胶-凝胶法和低温沉淀法两种方法制备了TiO2晶粒尺寸小于10 nm 的TiO2-SiO2纳米复合物表现出优异的高温稳定性，可在600℃以下保持稳定，并且负载型TiO2-SiO2纳米复合物增强了RuO2与TiO2相互作用，同时提高了催化剂活性和抗烧结性能。最后，基于以上研究结果，设计出理想的抗烧结催化剂结构模型，为开发低负载量、高活性、高稳定性的工业Deacon催化剂提供了理论依据。