Department of Chemistry, Wayne State University, Detroit, Michigan 48202, USA.
ACS Appl Mater Interfaces. 2013 Jun 26;5(12):5403-7. doi: 10.1021/am402003g. Epub 2013 Jun 12.
The synthesis of monodisperse 5-10 nm Pd5P2 catalytic particles by encapsulation in a mesoporous silica network, along with preliminary data on hydrodesulfurization (HDS) activity, is reported. Precursor Pd-P amorphous nanoparticles are prepared by solution-phase reaction of palladium(II) acetylacetonate with trioctylphosphine at temperatures up to 300 °C. Direct crystallization of Pd5P2 in solution by increasing the temperature to 360 °C leads to sintering, but particle size can be maintained during the transformation by encapsulation of the amorphous Pd-P particles in a mesoporous silica shell, followed by treatment of the solid at 500 °C under a reducing atmosphere, yielding Pd5P2@mSiO2. The resultant materials exhibit high BET surface areas (>1000 m(2)/g) and an average pore size of 3.7 nm. Access to the catalyst surface is demonstrated by dibenzodithiophene (DBT) HDS testing. Pd5P2@mSiO2 shows a consistent increase in HDS activity as a function of temperature, with DBT conversion approaching 60% at 402 °C. The ability to control particle size, phase, and sintering is expected to enable the fundamental catalytic attributes that underscore activity in Pd5P2 to be assessed.
本文报道了通过在介孔硅网络中封装制备单分散 5-10nmPd5P2 催化颗粒的方法，同时还报道了初步的加氢脱硫（HDS）活性数据。采用钯（II）乙酰丙酮盐与三辛基膦在高达 300°C 的温度下进行溶液相反应制备了无定型 Pd-P 前体纳米颗粒。通过将温度升高到 360°C 可直接在溶液中结晶出 Pd5P2，但升温会导致颗粒烧结，而通过将无定型 Pd-P 颗粒封装在介孔硅壳中，然后在 500°C 下于还原气氛中对固体进行处理，可以在转化过程中保持颗粒尺寸不变，从而得到 Pd5P2@mSiO2。所得材料具有高 BET 比表面积（>1000m2/g）和 3.7nm 的平均孔径。通过二苯并噻吩（DBT）HDS 测试证明了催化剂表面可接近。Pd5P2@mSiO2 的 HDS 活性随温度呈一致增加，在 402°C 时 DBT 的转化率接近 60%。预计控制颗粒尺寸、相和烧结的能力将能够评估 Pd5P2 中突出活性的基本催化特性。
