金合金@介孔氧化物核壳材料的制备及CO选择性催化氧化性能研究

The preferential oxidation reaction of CO in H2-rich atmosphere is the necessary procedure for the proton exchange membrane fuel cell (PEMFC). Due to the poor stability, Au catalysts limit its large scale application in removing the CO selectively. The Au@oxide core-shell structure can prohibit the aggregation of Au particles effectively because the oxide shells confine the Au particle in the core-shell structure. The practical application of hydrogen oxygen fuel cell request the catalysts keep the activity in a large temperature range and removing the CO down to 1000 ppm, and the activity and selectivity of the Au@oxide core-shell catalysts still need to be enhanced. Current project is aimed at the design and exploration of novel Au-based core-shell structure by enriching the metal composition of the Au-based core and adjusting the surface structure of the catalyst. Compared with the Au nanoparticle, the AuM bimetal nanoparticles will enhance the catalytic activity and selectivity by boosting the synergistic effect at the Au-M interface, which works by optimizing the absorption and activate way of reactant and catalyst. The catalytic property towards CO selective oxidation of the as-made catalysts will be evaluated and the corresponding microscopic reaction kinetics of the CO oxidation on the as-made catalysts will be studied to get the key factors of the catalytic property. The influence of Au-M components and the microscopic structure on the catalytic performance of the as-made catalysts will be investigated systematically. The nature of the synergistic effect between different species and the origin of the excellent catalytic performance will be clarified based on. The related investigations in this work are beneficial for providing new understandings for the gold heterogeneous catalysis as well as providing the new way to improve the gold catalysts.

富氢气体中选择性去除CO是质子交换膜燃料电池重整气预处理的必要步骤，目前广泛研究的金纳米催化剂稳定性较差限制了其实际应用。金@氧化物核壳结构可有效解决金纳米粒子在催化过程中的迁移聚合问题，但其在较高温度下的催化活性和选择性仍需进一步提高。本项目拟综合核壳结构和合金粒子两方面的优势来提高催化剂的性能，以金@介孔氧化物结构提高催化剂稳定性，并以金合金粒子作内核，利用金合金中多组分协同效应优化反应物在催化剂表面的吸附、活化方式，进而提高催化剂活性和选择性，获得综合性能（活性、选择性和稳定性）优异的金纳米催化剂。系统研究催化剂组分和微观结构对催化性能的影响，考察富氢气体中CO氧化反应在不同催化剂体系上的微观反应动力学特性，阐明多组分协同效应的作用方式，揭示CO催化活性和选择性的增强机制。本项目不仅为金纳米催化剂的高效稳定利用提供新的途径，而且为促进金基催化剂在氢气纯化中的发展和应用提供技术支持。

金纳米催化剂在CO催化氧化领域具有重要的应用潜力，但其在较高温度下的催化活性和稳定性仍需进一步提高。本项目综合了合金粒子和核壳/负载结构两方面的优势来提高催化剂的性能，获得了一系列金合金@介孔氧化物和金合金/氧化物结构等对CO催化氧化性能优异的催化剂。系统研究了催化剂组分和微观结构，如合金粒子的尺寸、Auδ+/Au0的比例、后处理方式、外壳氧化物暴露晶面、外壳氧化物孔道尺寸及比表面积等对催化剂活性和稳定性的影响，明确了影响催化剂性能的关键因素。利用H2-TPR和原位在线红外等表征手段获得了反应物在催化剂表面的吸附、活化方式和催化产物的脱附方式，揭示了多组分协同效应的作用方式，阐明了CO催化活性和稳定性的增强机制。本项目为金基纳米催化剂的高效稳定利用提供了新的方法，而且有望实现实际应用。