以Al₂O₃为载体,采用等体积浸渍法制备了Ni/Al₂O₃,利用XRD、N₂物理吸附、H₂-TPR和NH₃-TPD对Ni/Al₂O₃进行表征,并考察了其催化丁酮和甲醛羟醛缩合(aldol)反应产物脱水加氢制备甲基异丙基酮(MIPK)的反应性能。结果表明,在醛酮摩尔比为1.1、反应温度为50℃和反应时间为4 h的条件下,5%三乙胺催化丁酮和甲醛交叉aldol反应的转化率为61.5%,目标产物选择性超过90%;以此反应液为原料,Ni/Al₂O₃在240℃、0.1 MPa H₂和0.5 h^-1空速条件下能够实现80%的MIPK选择性和50%的MIPK收率。此外,Ni/Al₂O₃催化剂具有较高的结构稳定性,在脱水加氢反应中未出现明显的Ni粒子聚集。丁酮和甲醛羟醛缩合和催化加氢串联反应制备MIPK遵循平行-序列的反应路径,且产物选择性主要取决于丁酮和甲醛的定向aldol反应。

Ni/Al₂O₃ catalysts are prepared via an incipient wetness impregnation method with Al₂O₃ as carrier,and characterized by means of XRD,N₂ physical adsorption,H₂-TPR,and NH₃-TPD.The performance of Ni/Al₂O₃ catalysts is evaluated in catalyzing the production of methyl isopropyl ketone (MIPK) through hydrogenation of the products from aldol condensation reaction between methyl ethyl ketone (MEK) and formaldehyde.It is shown that the conversion of MEK reaches 61.5% and an overall selectivity of the desired aldol products exceeds 90% when 5% trimethylamine is served as catalyst,the molar ratio between formaldehyde and MEK is 1.1,temperature is 50℃,and the reaction lasts for 4 h.With the aldol products as feeding materials,the selectivity and yield of MIPK can realize 80% and 50%,respectively when Ni/Al₂O₃ catalysts are used at 240℃,0.1 MPa H₂,and a space velocity of 0.5 h^-1.Besides,Ni/Al₂O₃ catalysts are stable in the hydrogenation reaction without observable aggregation of Ni particles during a period of 80 h.It is indicated that the overall tandem reaction proceeds via a combination of parallel and consecutive steps,and the selectivity of MIPK relies mainly on the crossed aldol reaction between MEK and formaldehyde.

汪波(1995-),男,硕士研究生,研究方向为精细化工,442465746@qq.com。