调控反应条件引导磁性铜镍催化剂催化乙酰丙酸加氢合成γ-戊内酯的反应路径

Directing reaction pathways for hydrogenation of levulinic Acid into γ-valerolactone by regulating the reaction conditions over a magnetic Cu-Ni catalyst

采用溶胶凝胶法制备了铁磁性的铜镍催化剂,将其用于乙酰丙酸(LA)加氢合成γ-戊内酯(GVL)的反应中。在120~200℃、2~5MPa、m(催化剂)/m(乙酰丙酸)=0.1~0.3、m(水)/m(乙酰丙酸)=0.5~5的反应条件下,开展了一系列反应探索引导乙酰丙酸合成γ-戊内酯的反应路径。研究表明,LA加氢生成GVL有两条不同的路径:在低于150℃、高于2MPa,m(催化剂)/m(乙酰丙酸)>0.2的反应条件下,反应路径为乙酰丙酸先转化为羟戊酸,然后和甲醇酯化为羟戊酸甲酯,再经酸催化生成GVL;相反,在高于150℃、低于2MPa、m(催化剂)/m(乙酰丙酸)<0.2的反应条件下,反应路径为LA先和甲醇酯化生成乙酰丙酸甲酯,再加氢生成GVL。很显然,通过调控反应条件可以引导LA合成GVL的反应路径。

A magnetic Cu-Ni catalyst was prepared by sol-gel method and used for hydrogenation of levulinic acid （LA） to γ- valerolactone （GVL）. A series of experiments were carried out over a broad range of conditions （temperature： 120-200℃; pressure： 2-5MPa; catalyst to LA mass ratio： 0.1-0.3; water to LA mass ratio： 0.5-5） for exploring the directing reaction pathways. GVL can be formed by two distinct hydrogenation pathways. Under the conditions of lower than 150℃, higher than 2MPa and catalyst to LA mass ratio of higher than 20%, the mainly reaction pathway was as follow： firstly, LA being hydrogenated into 4-hydroxypentanoic acid （HA）, then methyl hydroxypentanoic （MHV） being formed by esterification of HA with methanol, and finally MHV being changed into GVL by acid catalysis. However, under the conditions of higher than 150℃, lower than 2MPa and the catalyst to LA mass ratio of lower than 20%, the reaction pathway was changed as follow： firstly, methyl levulinate （ML） being formed by esterification of LA with methanol, then ML being directly hydrogenated into GVL. Obviously, the reaction pathways could be directed by regulating the reaction conditions.