Byun Mi Yeon, Kim Ji Sun, Park Dae-Won, Lee Man Sig
Ulsan Regional Division, Korea Institute of Industrial Technology (KITECH), Ulsan 44413, Korea.
Department of Chemical and Biological Engineering, The University of British Columbia, Vancouver, BC, V6T 1Z4, Canada.
J Nanosci Nanotechnol. 2018 Sep 1;18(9):6283-6287. doi: 10.1166/jnn.2018.15643.
The increasing role of catalysis by noble metals coupled with their high price requires the development of cheaper and more effective catalysts, e.g., highly dispersed supported catalyst. Herein, Pd supported on Al2O3 catalysts prepared by deposition-precipitation under different conditions were subjected to X-ray diffraction, N2-physisorption, NH3/CO2 temperature programmed desorption, CO-chemisorption, and field-emission transmission electron microscopy analyses, which revealed that the size and distribution of Pd particles were influenced by Al2O3 support type (particle size and phase transition) and preparation conditions (metal precursor type, pH value, and solution temperature). The Pd/Al2O3 catalysts were prepared using type A (particle size = 3 micron) or type B (particle size = 20 nm) as a support and PdCl2 (PC) or Pd(NO3)2·2H2O (PN) as a Pd precursor, respectively. In XRD results, type A (particle size = 3 micron) Al2O3 had γ and phase, and type B (particle size = 20 nm) Al2O3 had only thermally stable γ phase. In addition, Pd dispersion and crystallite size showed an obvious dependence on pH value, solution temperature and attractive/repulsive forces between the functional groups of Al2O3 and Pd precursors. Optimal results were obtained using PdCl2 (PC) as a Pd precursor and type B (particle size = 20 nm) as a support at 60 °C and pH 5.5.
贵金属催化作用的日益增强及其高昂的价格，使得开发更便宜、更有效的催化剂成为必要，例如高分散负载型催化剂。在此，对通过不同条件下的沉积沉淀法制备的负载在Al2O3上的Pd催化剂进行了X射线衍射、N2物理吸附、NH3/CO2程序升温脱附、CO化学吸附以及场发射透射电子显微镜分析，结果表明Pd颗粒的尺寸和分布受Al2O3载体类型（粒径和相变）以及制备条件（金属前驱体类型、pH值和溶液温度）的影响。分别使用A型（粒径 = 3微米）或B型（粒径 = 20纳米）作为载体，以及PdCl2（PC）或Pd(NO3)2·2H2O（PN）作为Pd前驱体制备了Pd/Al2O3催化剂。在XRD结果中，A型（粒径 = 3微米）Al2O3具有γ相和θ相，而B型（粒径 = 20纳米）Al2O3仅具有热稳定的γ相。此外，Pd分散度和微晶尺寸对pH值、溶液温度以及Al2O3和Pd前驱体官能团之间的吸引/排斥力表现出明显的依赖性。以PdCl2（PC）作为Pd前驱体，B型（粒径 = 20纳米）作为载体，在60°C和pH 5.5的条件下获得了最佳结果。
