甘油氢解制1,2-丙二醇Cu/ZrO2催化剂的改性

Modification of Cu/ZrO2 catalysts for catalytic hydrogenolysis of glycerol to 1,2-propanediol

摘要:

用等体积浸渍法制备了一系列负载在ZrO2上的铜系催化剂，考察其在甘油气相氢解制1,2-丙二醇反应中的性能，并用BET、SEM、XRD和H2-TPR表征了催化剂的孔结构、形貌，晶相和还原性。用预备实验筛选了几种载体，发现SiO2活性和选择性最佳，但很快失活；ZrO2活性次之，而选择性较差。接着考察用共沉淀法在ZrO2载体中添加稀土元素Ce，La，Y的效果，发现均能显著提高催化活性和选择性，而加钇稳定的氧化锆(YSZ)载体性能最佳。最后，浸渍Ce对负载Cu催化剂进行改性，发现18%Cu-4%CeO2/YSZ催化剂活性和选择性最佳，1,2-丙二醇得率超过93%。表征分析发现该催化剂具有开放性孔结构，比表面积达到107m2/g，前躯体中CuO晶粒最小，还原温度最低。对最优条件下制备的催化剂进行了长运转考察，稳定运行超过1600hr，1,2-丙二醇得率维持在94%以上，具备工业化前景。

Abstract:

A series of ZrO2 supported copper catalysts were prepared by impregnation of incipient wetness method and tested in gas phase hydrogenolysis of glycerol to 1,2-propanediol. The pore structure, morphology, crystalline phase and reducibility of the catalysts were characterized by BET, TEM, XRD and H2-TPR, respectively. The effect of support was screened in preliminary tests, where SiO2 was found to be the best in activity and selectivity, but failed in stability; ZrO2was the next in activity, but inferior in selectivity. For purpose of modification, the elements of rare earths like La, Ce, Y were added in ZrO2 by coprecipitation method. The performance of catalysts was obviously improved after doping of La, Ce and Y in ZrO2 support, among which, yttria stabilized ZrO2 (YSZ) was the best. Later, Ce was introduced as a promoter by successive impregnation of Cu and Ce precursors. The best catalyst was found to be 18wt.%Cu-4wt.%CeO2/YSZ, with the yield of 1,2-propanediol over 93%. Instrumental characterization revealed that this catalyst contained an open pore structure and BET surface area 107m2/g, while its CuO crystal was also the smallest in size and easiest to reduce. Time-on-stream test was carried out with the thoroughly optimized catalyst, a 1,2-propanediol yield over 94% was maintained over 1600hr, foreseeing a prospect of commercialization.