Chu Yue, Zhang Qiang, Wu Tongwei, Nawaz Zeeshan, Wang Yao, Wei Fei
J Nanosci Nanotechnol. 2014 Sep;14(9):6900-6. doi: 10.1166/jnn.2014.8956.
Ultra-dispersed precious metal nanoparticles with good thermal stability are highly required for heterogeneous catalysis. However, the efficient and effective strategy to disperse ultra-fine precious metal nanoparticles at high reaction temperature is still not fully understood yet. In this contribution, a family of catalysts with ultra-small Pt nanoparticles were prepared using impregnation method by adjusting the zeolite content in the SAPO-34 and γ-Al2O3 mixed support. The effect of Pt nanoparticle size on the catalytic activity, selectivity, and stability was investigated in the propane dehydrogenation reaction. Catalyst with smaller Pt particles exhibits better catalytic performance. Both the highest Pt dispersion and the best catalytic activity can be achieved by using SAPO-34 and γ-Al2O3 mixed support with 70 wt.% of SAPO-34. The size and structure of the Pt nanoparticles on the optimal catalyst were characterized by transmission electron microscopy. Pt nanoparticles with an average size of 1.32 nm were observed. There were stronger metal-support interactions between the oxidized tin species and Pt particles on SAPO-34 support compared to that on γ-Al2O3 catalyst. These lead to high Pt dispersion and consequently good catalytic performance.
多相催化非常需要具有良好热稳定性的超分散贵金属纳米颗粒。然而，在高反应温度下分散超细贵金属纳米颗粒的有效策略仍未完全被理解。在本论文中，通过浸渍法，通过调整SAPO-34和γ-Al2O3混合载体中的沸石含量，制备了一系列具有超小Pt纳米颗粒的催化剂。在丙烷脱氢反应中研究了Pt纳米颗粒尺寸对催化活性、选择性和稳定性的影响。具有较小Pt颗粒的催化剂表现出更好的催化性能。使用含有70 wt.% SAPO-34的SAPO-34和γ-Al2O3混合载体可以实现最高的Pt分散度和最佳的催化活性。通过透射电子显微镜对最佳催化剂上Pt纳米颗粒的尺寸和结构进行了表征。观察到平均尺寸为1.32 nm的Pt纳米颗粒。与γ-Al2O3催化剂相比，SAPO-34载体上的氧化锡物种与Pt颗粒之间存在更强的金属-载体相互作用。这些导致了高Pt分散度，从而具有良好的催化性能。
