金属配比对IrRe催化剂结构及其甘油氢解催化性能的影响

Effect of Ir/Re Mole Ratio on Structure and Activity of Ir-Re/G-6 Catalyst in Glycerol Hydrogenolysis

采用分步-等体积浸渍法制备了不同Ir/Re摩尔比的Ir-Re/G-6双金属催化剂,并应用于甘油氢解制备1,3-丙二醇反应,利用XRD、TEM、H_2-TPR、XPS、NH_3-TPD、Py-IR和CO-DRIFTs等手段对催化剂进行了系统表征,探讨了Ir/Re摩尔比对Ir-Re催化剂结构、性质及其催化性能的影响.研究结果表明:Ir/Re摩尔比对Ir-Re双金属催化剂的合金结构和酸性能影响显著,并决定了其甘油氢解催化性能;当Ir/Re摩尔配比为1.0时,能形成高度分散的Ir-Re合金结构催化剂,具有最多的表面Brnsted酸性位(Ir-Re-OH),表现出最高的甘油转化率和较好的1,3-丙二醇选择性.

A series of bimetallic Ir-Re/G-6 catalysts with different Ir/Re mole ratios were synthesized by impregnation method using H2 Ir Cl6 and NH4 ReO4 as precursors. The physiochemical properties of the catalysts were investigated by the techniques of X-ray diffraction（XRD）,transmission electron microscopy（TEM）,H2 temperature-programmed reduction（H2-TPR）,X-ray photoelectron spectroscopy（XPS）,NH3 temperature-programmed desorption（NH3-TPD）,pyridine adsorption Fourier-transform infrared（Py-IR） and in-situ CO adsorption diffuse reflectance infrared Fourier transform spectroscopy（CO-DRIFTs）. These catalysts were examined in a 100 m L stainless steel autoclave in glycerol hydrogenolysis. Results demonstrated that the Ir/Re mole ratio could greatly impact on the IrRe alloy structure and acid density,thus varied activity of the catalysts; When the Ir/Re mole ratio was 1.0,the4 Ir-4 Re/G-6 catalyst had the highly dispersed Ir-Re alloy structure and the largest number of surface acid sites,known as Ir-Re-OH,resulting in the best performance in glycerol hydrogenolysis to 1,3-propanediol.