摘要
以Cu-Zn-Al和Cu-Mg-Al类水滑石为前体经焙烧、还原制备了铜基催化剂,采用XRD、H2-TPR、N2吸附、H2-TPD、NH3-TPD、CO2-TPD及活性评价等方法,研究了M2+离子(M2+=Zn2+或Mg2+)及n(M2+)/n(Al3+)比对催化剂结构和甘油氢解反应性能的影响。结果表明,经450℃焙烧后,类水滑石转变为由尖晶石和/或氧化物组成的氧化态前驱体,再经270℃还原后制得高分散Cu催化剂。随氧化铝含量提高,催化剂比表面及酸量增加。Cu-Zn-Al催化剂表面氢吸附量大于CuMg-Al。Cu-Mg-Al催化剂碱性强于Cu-Zn-Al。Cu-Zn-Al[n(Cu)∶n(Zn)∶n(Al)=1∶1∶4]催化剂具有较佳甘油氢解活性及1,2-丙二醇选择性,这与其具有较多表面铜中心、较大酸量及Zn物种参与氢吸附有关。此外,Cu-Mg-Al催化剂表面铜中心和碱中心可能存在协同作用促进甘油氢解反应。
Cu-Zn-Al and Cu-Mg-Al catalysts were prepared from hydrotalcite-like precursors after calcination and reduction. The effect of M2 ＋（ M = Zn or Mg） and M2 ＋/ Al3 ＋ratio on the catalyst structure and performance were investigated by means of XRD,H2-TPR,N2-sorption,H2-TPD,NH3-TPD,CO2-TPD and activity test. The hydrotalcite-like precursors were transformed to the spinel and / or metal oxides after calcination at 450 ℃,from which the highly dispersed Cu-based catalysts were prepared after reduction at 270 ℃. Compared with the Cu-Mg-Al catalysts,the Cu-Zn-Al catalysts had more amounts of adsorbed hydrogen due to the role of Zn species. With increasing Al2O3 content,the specific surface area and acid amount increased. The Cu-Mg-Al catalysts had more basic sites than the Cu-Zn-Al catalysts. In the hydrogenolysis of glycerol,Cu-Zn-Al[n（ Cu） ∶ n（ Zn） ∶ n（ Al） = 1∶ 1∶ 4] had the highest activity and selectivity to 1,2-propanediol,which is due to the largest amounts of surface Cu and acid sites. For the CuMg-Al catalysts,there may be a synergism between the Cu and basic sites.
出处
《化学工业与工程》
CAS
CSCD
2015年第2期25-30,共6页
Chemical Industry and Engineering
关键词
类水滑石
甘油氢解
1
2-丙二醇
铜镁铝
铜锌铝
hydrotalcite-like compound
glycerol hydrogenolysis
1
2-propanediol
Cu-Mg-Al catalyst
Cu-Zn-Al catalyst
