Co-B/γ-Al_2O_3非晶态催化剂的制备及其催化乳酸乙酯液相加氢性能

Preparation of Amorphous Co-B/γ-Al_2O_3 Catalyst and Its Performance in Catalytic Liquid Phase Hydrogenation of Ethyl Lactate

采用浸渍-还原法制备了负载型Co-B/γ-Al2O3非晶态合金催化剂,并将其应用于乳酸乙酯液相加氢制备1,2-丙二醇(1,2-PDO)反应中,研究了其催化加氢性能.采用电感耦合等离子体(ICP)发射光谱仪、X射线衍射(XRD)仪、透射电子显微镜(TEM)、差示扫描量热(DSC)、X射线光电子能谱(XPS)等手段对催化剂的性能进行了表征,考察了制备条件对催化剂性能的影响.结果表明,新鲜的Co-B/γ-Al2O3催化剂具有非晶态结构,Co-B均匀地分散在载体γ-Al2O3上.随着Co负载量的增加,催化剂的热稳定性提高,催化剂表面Co/B原子比增加.当金属Co理论负载量为30%(质量分数,w)时,Co-B/γ-Al2O3催化剂表现出最高的加氢催化性能,在160°C,氢气压力为6.0 MPa条件下反应9 h,乳酸乙酯的转化频率(TOF)为1.41 h-1,转化率达到93.63%,1,2-丙二醇的选择性达到96.10%.催化剂的加氢性能取决于其分散均匀的Co-B纳米粒子、较高的表面Co/B原子比及Co和B之间的电子转移效应.

Supported cobalt amorphous catalysts Co-B/γ-Al2O3 were prepared using an impregnation-chemical reduction method for liquid phase hydrogenation of ethyl lactate to 1,2-propanediol（1,2-PDO）. The Co-B/γ-Al2O3 catalysts were characterized using inductively coupled plasma（ICP） optical emission spectrometry, X- ray diffraction（XRD）, transmission electron microscopy（TEM）, differential scanning calorimetry（DSC）, and X-ray photoelectron spectroscopy（XPS）. The effects of the catalyst preparation conditions on the hydrogenation of ethyl lactate were investigated. All the fresh catalysts showed an amorphous structure and Co-B particles were dispersed uniformly on the γ-Al2O3 support. The thermal stability of the amorphous catalyst and the Co/B atomic ratio of surface composition increased with increasing the Co content. The Co-B/γ-Al2O3 amorphous catalyst showed the highest catalytic activity when the theoretical loading of metal Co was 30%（mass fraction, w）. The ethyl lactate turnover frequency（TOF）, conversion, and selectivity to 1,2-PDO reached 1.41 h-1, 93.63%, and96.10%, respectively at a reaction temperature of 160 °C and hydrogen pressure of 6.0 MPa for 9 h. The higher catalytic performance of the 30%（w） Co- B/γ-Al2O3 supported amorphous catalyst is attributed to its highly dispersing Co-B particles, higher Co/B atomic ratio of surface composition, and electron transfer effect between Co and B.