Cu-Mn-Si催化剂的制备及其在仲丁醇脱氢反应中的应用

PREPARATION OF Cu-Mn-Si CATALYST AND ITS APPLICATION IN_(2)-BUTANOL DEHYDROGENATION

分别采用共沉淀法和溶胶凝胶法制备Cu-Mn-Si催化剂,考察其在仲丁醇脱氢制甲乙酮反应中的催化性能。通过X射线衍射、程序升温还原、N_(2)吸附-脱附和程序升温氧化对两种方法制备的催化剂进行表征。结果表明,不同方法制备的催化剂,其中的铜锰络合物(CuMn_(2)O_(4))晶相结构不同。共沉淀法、溶胶凝胶法制备的催化剂中CuMn_(2)O_(4)晶相分别归属于JCPDS 71-1142和JCPDS 34-1400。溶胶凝胶法制备的催化剂晶粒小、分散性好、比表面积大,因而活性较高,Mn的加入没有提高催化剂的性能。Mn的加入可以降低共沉淀法制备的催化剂的还原温度,提高催化剂中Cu组分的分散程度,因而提高了催化剂的性能。溶胶凝胶法所制备的催化剂中,Cu SiO_(2)催化剂具有最高的仲丁醇转化率、甲乙酮选择性和甲乙酮收率,分别达99.26%,99.19%,98.45%;共沉淀法制备的催化剂,当n(Cu)∶n(Mn)∶n(Si)=0.8∶0.2∶1.0时,具有最高的仲丁醇转化率,可达94.92%,其甲乙酮选择性略低于Cu SiO_(2)催化剂,为98.53%,甲乙酮收率为93.52%。

Cu-Mn-Si catalysts were prepared by coprecipitation method and sol-gel method respectively,and their performance in the reaction of 2-butanol dehydrogenation to methyl ethyl ketone was investigated.The catalysts prepared by the two methods were characterized by X-ray diffraction,programmed temperature reduction,nitrogen adsorption desorption and temperature programmed oxidation.The results showed that the crystal structures of Cu-Mn complex in the catalysts prepared by different methods were different.The crystal phase of CuMn_(2)O_(4) in the catalyst prepared by coprecipitation and sol-gel methods belonged to JCPDS 71-1142 and JCPDS 34-1400,respectively.The catalyst prepared by sol-gel method had small crystal size,good dispersion and large specific surface area,so it had high activity.The addition of Mn did not improve the performance of the catalyst prepared by sol-gel method,but could decrease the reduction temperature of the catalyst prepared by coprecipitation method and improve the dispersion of copper components in the catalyst,thus improving the performance of the catalyst.Among the catalysts prepared by sol-gel method,Cu-Si catalyst had the highest conversion rate of 2-butanol,selectivity and yield of methyl ethyl ketone,reaching 99.26%,99.19%and 98.45%,respectively.When n(Cu)∶n(Mn)∶n(Si)=0.8∶0.2∶1,the catalysts prepared by coprecipitation method had the highest conversion rate of 2-butanol,reaching 94.92%,the selectivity of methyl ethyl ketone was 98.53%,and the yield of methyl ethyl ketone was 93.52%.