Zn对二氟乙酸乙酯加氢合成二氟乙醇Cu-Al-Zn催化剂结构和性能的影响  

Effect of Zn Promoter on the Textural Structure and Performance of the Cu-Al-Zn Catalysts for the Hydrogenation of Ethyl difluoroacetate to Difluoroethanol

作　　者：孙道安[1] 李春迎[1] 杜咏梅[1] 张伟[1] 张建伟[1] 马洋博[1] 曾纪君[1] 吕剑[1] 

机构地区：[1]西安近代化学研究所,陕西西安710065

出　　处：《分子催化》2013年第3期242-249,共8页Journal of Molecular Catalysis(China)

基　　金：陕西省科技攻关(批准号:2010K07-06)资助

摘　　要：采用共沉淀法制备了系列不同Zn含量的Cu-Al-Zn催化剂.以二氟乙酸乙酯为原料,在反应釜中考察了Cu-Al-Zn对二氟乙酸乙酯催化加氢合成二氟乙醇的反应性能,并采用X射线粉末衍射(XRD)、N2吸脱附(BET)、程序升温还原(TPR)以及X射线光电子能谱(XPS)对催化剂结构进行了表征.评价结果表明,适量的Zn助剂极大地提高了反应转化率和选择性.在温度为200℃,压力为9 MPa,原料溶剂比为1∶3的条件下,反应8 h,Cu-Al-Zn(60∶20∶20,氧化物质量比)催化剂性能最佳,转化率和选择性分别可达99.5%和97.3%,在此条件下,催化剂重复使用12次活性无明显下降,催化剂具有良好的稳定性.表征结果显示,催化剂表面铜物种含量随着Zn含量增加而增多,并且整体上其还原性能随着Zn含量增加而改善,但是过量的Zn助剂容易导致还原或反应过程中催化剂铜颗粒的增长或团聚,适量的Zn助剂使催化剂表面铜物种含量适宜,且还原性能适中,能明显限制催化剂还原铜颗粒的增长或团聚.Cu-Al-Zn catalysts with different content of Zn promoter were prepared by coprecipitation method and their catalytic performance for the hydrogenation of ethyl difluoroacetate to difluoroethanol was systematically investigated.Characterization methods including X-ray diffraction,N2-physisorption,H2-temperature-programmed reduction and X-ray photoelectron spectroscopy were carried out to elucidate the structure evolution of the catalyst with the catalytic performance.Experimental results showed that the proper content of Zn promoter greatly enhanced the catalytic performance of Cu-based catalysts.99.5% ethyl difluoroacetate conversion and 97.3% difluoroethanol selectivity could be abtained over the Cu-Al-Zn（wt=60∶20∶20） catalyst under the tempruture of 200 ℃,the pressure of 9 MPa,the raw material solvent ratio of 1∶3 and the reaction time of 8 h.The Cu-Al-Zn（wt=60∶20∶20） catalyst could be repearted for twelve times with no obvious activity decline proving its good stability.The content of copper species increased with increasing Zn content,as well as the reduction ability was improved.However,excess Zn content could easily resulted in the agglomeration of copper species in the preparation and reaction processes,the opposite effect of which was the moderate Zn content.

关 键 词：共沉淀法 二氟乙酸乙酯 二氟乙醇 催化加氢 

分 类 号：O614.4[理学—无机化学]