基于原子层沉积构筑单原子Pd催化膜

Membrane catalysis process is an important research area affecting the future of the chemical and petrochemical, and the key is to prepare high-performance catalytic membranes. Due to low contents of the active components in unit volume catalytic membranes, the catalytic efficiencies of the present catalytic membranes are lower, and cannot compete with the powder catalysts. As a result, the preparation and application of catalytic membranes are still on the laboratory scale. The project suggests a new idea to develop high-performance catalytic membranes based on the components themselves: loading single-atom Pd on the membrane surface and in the membrane pores using atomic layer deposition (ALD). The project focus on the following three key scientific issues: the influence laws of the membrane surface characteristics on the Pd nucleation and growth; the matching relationships between the diffusion rate of the precursor and the pore size and thickness of the membrane; the deactivation mechanisms of the catalytic membrane and the corresponding inhibiting methods. The aim of the project is to design and prepare the Pd catalytic membranes with high catalytic performance by systematically analyzing and studying the synthesis of Pd catalytic membranes with ALD, adjusting the membrane surface properties, building the structure-activity relationships of the catalytic membranes, developing the methods to inhibit the Pd microstructure evolution, and achieving the loading of single atom Pd on the membrane surface and in the membrane pores with high density and good stability. The implementation of the project would provide some references for the synthesis of catalytic membranes with high catalytic performance.

膜催化过程是影响化工与石油化工未来的重要研究领域，其核心是高性能催化膜的制备。催化膜的制备及应用还处于实验室探索研究阶段，其关键问题是由于单位体积膜面积的限制，催化膜中活性组份含量少，催化效率较低，同粉末催化剂相比不具竞争性。针对这一关键问题，本项目拟立足于活性组份本身，采用原子层沉积技术（ALD）在膜表面及孔道内负载单原子Pd催化剂，提高活性组份使用效率，构筑高性能催化膜。重点研究膜表面特性对Pd成核及生长的影响规律、前驱体扩散速率与膜孔径、厚度之间的匹配关系、催化膜失效及抑制机制等三个关键科学问题，系统剖析、研究ALD制备Pd催化膜过程，发展膜表面物性调控方法，构建Pd催化膜的构效关系，发展抑制Pd微结构演变的方法，实现单原子Pd在膜表面及孔道内的高密度负载，并保持良好的稳定性，设计、制备出催化性能优异的Pd催化膜。本项目的实施将为高性能催化膜的制备提供新的思路，促进催化膜的发展。

膜催化过程是影响化工与石油化工未来的重要研究领域，其核心是高性能催化膜的制备。由于单位体积膜面积的限制，活性组分含量少，催化膜催化效率较低，同粉末催化剂相比不具竞争性。针对这一关键问题，本项目立足于活性组分本身，采用原子层沉积技术（ALD）在膜表面及孔道内负载Pd催化剂，构筑高性能催化膜，主要研究进展如下。.1、基于陶瓷膜高的深径比、活性组分难以在膜孔道中沉积的特性，设计了专用反应腔、膜组件等，使前驱体气体通过强制对流方式，不断经过膜表面及孔道内部，在陶瓷膜的表面及孔道内部均负载活性组分。.2、利用原子层沉积技术在Al2O3陶瓷膜上沉积金属Pd，制备Pd/陶瓷催化膜，构建了催化膜反应器系统，着重研究了沉积参数，如Pd(hfac)2的脉冲时间、曝光时间，沉积温度，循环次数等对沉积Pd的微观结构及Pd/Al2O3催化膜催化性能的影响，发现沉积参数显著影响Pd/Al2O3催化膜的催化活性，适宜的沉积参数为：Pd(hfac)2脉冲时间0.3 s，Pd(hfac)2曝光时间120 s，沉积温度200 oC。.3、在陶瓷膜表面沉积TiO2等，并在不同气氛下煅烧，调节TiO2的表面化学环境，研究揭示陶瓷膜表面特性对Pd纳米颗粒与膜微结构的影响规律，发现在氢气气氛下煅烧能够显著增加TiO2氧空位浓度，促进Pd的沉积，提高催化膜的催化活性。以对硝基苯酚催化加氢为模型反应评估Pd/CM-TiO2-H催化膜的催化稳定性，采用XPS、TEM、ICP等技术对回收催化膜Pd/CM-TiO2-H的微结构进行了表征，揭示了催化膜微结构演变规律及失活机制。.以上研究过程中，在AIChE Journal、Chemical Engineering Science、Industrial & Engineering Chemistry Research等化工类期刊上发表SCI论文14篇；申请了发明专利5件。