CuZn溶胶中不同溶剂对CuZnAl浆状催化剂催化合成气制乙醇性能影响

Effects of CuZn sol prepared with different solvents on catalytic performance of CuZnAl slurry catalyst for syngas to ethanol

合成气直接合成乙醇涉及碳一化学中碳链增长与碳链终止两个共性问题。在完全液相两步水解法基础上,通过改变CuZn溶胶溶剂,调控完全液相CuZnAl乙醇合成催化剂的结构和表面态。结合浆态床催化剂性能评价结果,通过XRD、XPS、TEM、N_(2)吸/脱附、H_(2)-TPR及O_(2)程序升温氧化-质谱等表征手段,研究了所制备的3种催化剂的构效关系。结果表明,以乙醇和乙二醇为溶剂制备的Cat.et和Cat.eg催化剂,反应前后均为片层状结构,结构稳定;Cat.et催化剂比表面积大,CO转化率最高,总醇中乙醇占比最高(55.5%);Cat.eg催化剂比表面积次之,乙醇占比最低。以水为溶剂的Cat.w催化剂,结构中存在较多以ZnO为主要成分的纺锤体,组分分布不均匀,ZnO覆盖于Cu;上构成了Cu-ZnO甲醇活性位点;其比表面积最低,CO转化率最低,乙醇占比低于Cat.et。研究认为,所制备催化剂存在两种碳链增长路径,一是通过表面CH;物种的CO插入,二是通过表面CHO的偶联,以第一种路径为主;催化剂表面高Cu;相对量是选择性生成乙醇的关键,孔径尺寸与乙醇占比正相关。

The direct synthesis of ethanol from syngas involves two common problems of carbon chain growth and carbon chain termination in C1 chemistry. Based on the complete liquid phase two-step hydrolysis method, the structure and surface state of the complete liquid phase CuZnAl ethanol synthesis catalyst were regulated by changing the CuZn sol solvent. Combined with the reaction evaluation of slurry bed catalysts, the structure-activity relationship of the three catalysts was studied by XRD, XPS, TEM,N_(2)adsorption/desorption, H_(2)-TPR and O_(2)temperature programmed oxidation with mass spectrometry. The results show that the catalysts Cat.et and Cat.eg with ethanol and glycol as solvents have stable lamellar structure before and after the reactioN_(2) catalyst Cat.et has large specific surface area, the highest CO conversion rate and the highest proportion of ethanol(55.5%) in total alcohol;the specific surface area of catalyst Cat.eg is smaller than that of Cat.et and its proportion of ethanol is the lowest. In catalyst Cat.w with water as solvent, there are many ZnO spindles leading uneven component distribution, coverage of ZnO on Cu~0 to form CuZnO methanol active site;its specific surface area is the lowest, the conversion rate of CO is the lowest and the proportion of ethanol is lower than that of Cat.et. The research shows that there are two paths for carbon chain growth on the prepared catalysts, one is CO insertion to surface CH_(2)Species, the other is coupling of surface CHO, and the first path is the main path;the high concentration of surface Cu;is the key for selective production of ethanol, and the pore size has a positive correlation with the proportion of ethanol.