原子层沉积法制备限域型Pt基催化剂及其苯酚催化性能

Preparation and Catalytic Performance of the Confined Pt Catalyst by Atomic Layer Deposition

选择合适的载体负载贵金属Pt纳米粒子,对于制备高效的苯酚加氢催化剂具有重要意义。使用原子层沉积技术,以碳纳米纤维作为模板,在其表面依次沉积Pt纳米粒子,厚的氧化钛壳层,通过高温烧结除去模板,得到限域在氧化钛纳米管内壁的Pt纳米粒子。在500℃烧结温度下Pt纳米粒子的粒径在2.0~3.2 nm之间,平均粒径为2.6 nm,尺寸高度一致,均匀地分散并且嵌入到氧化钛纳米管的中空管道内壁。与常规负载在氧化钛纳米管外壁的Pt纳米粒子相比,该限域催化剂的催化转化率更高,在500℃烧结温度下转化频率(TOF)值为482.1 h^(−1),表现出更好的催化活性,而且由于氧化钛纳米管的保护作用,可有效防止Pt纳米粒子在反应过程中的聚集和脱落,在反应后Pt的质量分数仅降低了4.52%,其形貌也没有发生明显改变,从而表现出优异的催化稳定性。

It is of great significance to select appropriate supports to support Pt nanoparticles for the preparation of efficient phenol hydrogenation catalysts.In this paper,Pt nanoparticles confined into the inner wall of titanium oxide nanotubes were prepared by template assisted method of atomic layer deposition technology.The specific preparation method was to use carbon nanofibers as templates,successively depositing Pt nanoparticles and thick titanium oxide shell on the templates surface.Then,the templates were removed by high-temperature sintering,through which Pt nanoparticles confined into the inner wall of titanium oxide nanotubes can be obtained.The particle size of the Pt nanoparticles ranged from 2.0 to 3.2 nm at a sintering temperature of 500℃,with an average size of 2.6 nm.Transmission electron microscopy results confirmed that Pt nanoparticles with highly uniform size were evenly dispersed and embedded into the inner wall of the hollow channel of titanium oxide nanotubes.The results of the catalytic performance of phenol hydrogenation show that the small-size Pt nanoparticles have the best phenol hydrogenation activity,with a Turnover Frequency(TOF)value of 482.1 h^(−1) at a sintering temperature of 500℃.In addition,compared with the conventional Pt nanoparticles with the same size supported on the outer wall of titanium oxide nanotubes,it is found that the confined catalyst shows better catalytic activity.Furthermore,due to the protective effect of titanium oxide nanotubes,it can effectively prevent the aggregation and falling off of Pt nanoparticles in the reaction process.After the reaction,the Pt content only decreased by 4.52%,and there were no significant changes in the morphology observed,thus the confined catalyst showing excellent catalytic stability compared with the supported catalyst.