采用浸渍法、共沉淀法、水热法和碳微球硬模板法制备了Ni/ZnO催化剂,运用X射线衍射、程序升温还原、透射电子显微镜和氢滴定等手段对其进行了表征,并用于连续固定床反应器中无外加氢气条件下的丙三醇重整-氢解反应.结果表明,在较低空速下,生成的1,2-丙二醇(1,2-PDO)易在Ni分散度较高的催化剂上进一步裂解为乙醇和气相产物;而在较高空速下,其选择性受制于中间产物丙酮醇的加氢.在优化的空速下,Ni分散度越高越有利于1,2-PDO的生成.在Ni分散度最高的Ni/ZnO催化剂上,当丙三醇质量空速为0.84h-1时,1,2-PDO选择性最高,为54.9%,丙三醇转化率为85.4%.
The catalytic conversion of glycerol to 1,2-propanediol (1,2-PDO) is generally conducted batch-wise in an autoclave in the pres- ence of high pressure H2. The reforming and hydrogenolysis of glycerol to 1,2-PDO over Ni/ZnO catalysts in a continuous flow fixed-bed reactor without added H2 was reported. The Ni/ZnO catalysts were prepared by wetness impregnation (WI), co-precipitation (CP), hydro- thermal treatment (HT), and carbon microsphere hard-templating (CT) methods. The catalysts were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), transmission electron microscopy (TEM), and H2 titration. At a low weight hourly space velocity (WHSV) of glycerol, the 1,2-PDO produced got degraded to ethanol and gas phase products over catalysts with high Ni dispersion, while at a high WHSV, the selectivity for 1,2-PDO was limited by the hydrogenation of the acetol intermediate. At the optimized WHSV, the catalyst with a higher Ni dispersion was more selective for 1,2-PDO, and over the Ni/ZnO catalyst with the highest Ni dispersion, the highest selectivity of 54.9% for 1,2-PDO was obtained at a glycerol conversion of 85.4% at the WHSV of 0.84 h-1.