纳米氧化锌的制备方法对合成碳酸二甲酯性能的影响

Influence of Nano-sized ZnO's Different Preparati on Methods on the Performance of DMC's Synthesis

采用不同母体、不同制备方法制备了纳米氧化锌,利用XRD, TEM和BET等手段对样品进行了表征,并对其催化尿素与甲醇合成碳酸二甲酯(DMC)反应性能进行了评价.以碳酸钠作沉淀剂制备得到粒径为14～28nm的ZnO催化剂;以醋酸锌和四甲基氢氧化铵(TMAH)为原料,利用溶胶-凝胶技术制备得到了粒径分布均匀的ZnO催化剂,平均粒径为50nm.在n(尿素):n(甲醇)=1:45,催化剂占反应体系总质量的2.4%,反应温度170℃,反应时间6h,初始压力1.6MPa的反应条件下评价催化剂催化性能,发现以尿素为沉淀剂制备的ZnO活性最高,DMC收率达7.66%;而以醋酸锌和四甲基氢氧化铵为原料制备的ZnO比活性最高,达0.673.

A series of nano-sized zinc oxide samples were prepared using different starting matrials via different methods,and were characterized by means of XRD,TEM,and BET.Their catalytic performance was evaluated in the reaction for the synthesis of dimethyl carbonate(DMC) from urea and methanol.The particle size of ZnO prepared using sodium carbonate as precipitator was in the range of 14~28nm while the mean particle size of ZnO prepared using sol-gel process was 50nm.Under the reaction conditions of n(urea):n(methanol) = 1:45,weight percentage of ZnO 2.4%,reaction temperature 170℃,reaction time 6h,and initial pressure 1.6MPa,DMC yield attained 7.66% over ZnO catalyst prepared using urea as precipitator and the specific activity attained 0.673 over ZnO catalyst using zinc acetate and TMAH as material.