MoNi/γ-Al_2O_3催化剂的制备及其催化乙酸临氢酯化反应性能

MoNi/γ-Al_2O_3 Catalyst:Preparation and Catalytic Activity for Acetic Acid Hydrotreating

采用等体积浸渍的方法制备了MoNi/γ-Al2O3系列催化剂,利用XRD和TPR手段表征了其结构随Mo助剂的添加量和催化剂还原温度的变化,并考察了在3 MPa的氢气压力下,乙酸催化酯化的反应性能。结果表明,添加助剂Mo有利于Ni均匀地分散,减弱了Ni与Al之间的相互作用,抑制了NiAl2O4尖晶石结构的形成,降低了催化剂的还原温度。催化剂经600℃还原后,NiO被还原为Ni0。当加入经过600℃还原的催化剂MoNi/γ-Al2O3后,乙酸临氢反应转化率显著提高,可达33.2%。在3 MPa的氢气压力下,乙酸反应的途径可能为一部分乙酸被还原得到乙醇,乙醇与未还原的乙酸发生酯化,以乙酸乙酯和水为反应产物。

MoNi/γ-Al2O3 catalysts were prepared by the impregnation method. The catalyst samples were characterized by XRD and TPR. The effects of Mo promoter content and the catalyst reducing temperature on hydrotreatment activity of the catalyst were studied under 200 ℃ and 3 MPa hydrogen pressure using acetic acid as the model compound. The XRD results indicate that the addition of Mo promoter is beneficial to the uniformity of nickel species on the catalyst and decreases the interaction between nickel species and the support which results in the decrease the of NiAl2O4 spinel formation. The addition of Mo promoter also decreases the reducing temperature of the catalyst. After the catalyst of 0.06 MoNi/γ-Al2O3 being reduced under the atmosphere of H2/N2（5/95, V/V）, nickel oxide was reduced to Ni^0. The reaction was promoted obviously upon the addition of the MoNi/γ-Al2O3 catalyst reduced at 600 ℃. The Mo-modified Ni/γ-Al2O3 catalyst reduced at 600 ℃ displayed the highest activity during the reaction, the conversion of acetic acid reached the highest point of 33.2%. The products included ethyl acetate and water.