Mg3(PO4)2修饰铂钨锆复合氧化物的性能

Properties of platinum-tungsten-zirconium composite oxide modified with magnesium phosphate

采用浸渍-焙烧法制备不同含量Mg3(PO4)2修饰的铂钨锆复合氧化物(Pt-WO3/ZrO2)。采用N2吸附-脱附、X线衍射仪(XRD)、傅里叶红外光谱仪(FT-IR)、NH3程序升温脱附(NH3-TPD)、H2程序升温还原(H2-TPR)以及CO脉冲吸附等手段对Mg3(PO4)2修饰的Pt-WO3/ZrO2进行表征。通过连续的固定床反应器对Mg3(PO4)2修饰的Pt-WO3/ZrO2催化甘油氢解的稳定性能进行评价,并利用水热釜对修饰前后的WO3/ZrO2载体进行水热稳定性研究。结果表明:一定量Mg3(PO4)2修饰的Pt-WO3/ZrO2,ZrO2的四方相较单斜相增长较多,总酸量增加,Pt的分散度增大,金属的还原性能增强,其中2%Mg3(PO4)2修饰的Pt-WO3/ZrO2催化甘油氢解的稳定性能较为显著,200 h内反应基本趋于稳定。一定量Mg3(PO4)2的引入有效地促进了ZrO2晶型的转变,促使其他晶型的ZrO2更多地转变为四方相的ZrO2,阻止了WO3/ZrO2载体总酸量的降低和孔道结构的坍塌,从而提高了WO3/ZrO2载体的水热稳定性。

Platinum-tungsten-zirconium composite oxides(Pt-WO3/ZrO2) modified with different contents of Mg3(PO4)2 were prepared by impregnation-calcination method. The modified Pt-WO3/ZrO2 were characterized by N2 adsorption and desorption, X-ray diffraction(XRD), Fourier transform infrared spectroscopy(FT-IR), NH3 temperature program desorption(NH3-TPD), H2 temperature programmed reduction(H2-TPR), and CO pulse adsorption. The catalytic stability of Mg3(PO4)2 modified Pt-WO3/ZrO2 for glycerol hydrogenolysis were evaluated by a continuous fixed bed reactor as well as the WO3/ZrO2 carrier modified by hydrothermal kettle to study hydrothermal stability. Results showed that the tetragonal phase of ZrO2 increased more than monoclinic phase, the total acid content, the dispersion of Pt and the reduction property of metal increased with a certain amount of Mg3(PO4)2 modified Pt-WO3/ZrO2. Among them, the stability of hydrogenolysis of glycerol catalyzed by 2%Mg3(PO4)2 modified Pt-WO3/ZrO2 was remarkable within 200 h. The introduction of a certain amount of Mg3(PO4)2 effectively promoted the transformation of ZrO2 crystal form and promoted the ZrO2 of other crystalline forms to become tetragonal ZrO2. The decrease of total acid content of WO3/ZrO2 carrier was prevented, and the collapse of pore structure, thus the hydrothermal stability of WO3/ZrO2 carrier was improved.