焙烧温度对CuO/ZrO_(2)催化剂催化草酸酯加氢性能的影响

Effect of calcination temperature on performance of Cu/ZrO_(2) catalyst for oxalates hydrogenation

采用乙酸络合法一锅制备催化剂前驱体,再经过不同温度焙烧制得CuO/ZrO_(2)催化剂,用于草酸二甲酯(DMO)加氢制乙二醇(EG)。利用SEM、XRD和化学吸附等对催化剂进行表征与活性评价,结果表明,焙烧温度影响催化剂的微观结构和催化活性:低温焙烧所得催化剂表面CuO颗粒分布均匀且粒径较小,所以易还原且催化性能较好;而高温焙烧所得催化剂表面颗粒发生团聚且Cu物种聚集,使得表面Cu质量分数远大于体相浓度且粒径变大,导致催化性能减弱;550℃焙烧所得催化剂的催化性能最好,在液时空速为0.5 h^(-1)时,DMO转化率约为97.7%,EG选择性高达95.3%。

The precursor is prepared by means of acetic acid complexation method in one pot,and CuO/ZrO_(2)catalyst is prepared by roasting the precursor at different temperature,which is used in the hydrogenation of dimethyl oxalate(DMO)to make ethylene glycol(EG).The characterization and activity evaluation of the catalyst are performed by means of scanning electron microscope(SEM),X-ray diffraction(XRD)and chemisorption.It is found that calcination temperature affects the microstructure and catalytic activity of the catalyst.Cu O particles on the surface of the catalyst obtained by low-temperature calcination have uniform distribution and small particle size,so the catalyst is easy to reduce and has good catalytic performance.On the other hand,the surface particles of the catalyst obtained by hightemperature calcination agglomerate and Cu species also do,so that the surface Cu content is much larger than the bulk concentration,and the particle size becomes larger,resulting in weakening of the catalytic performance.Among them,the catalyst calcined at 550℃has the best catalytic performance,over which DMO conversion rate is about 97.7%and EG selectivity is as high as 95.3%when the liquid hourly space velocity is 0.5 h^(-1).