甘油与环己酮缩合反应催化剂的研究

通过比较Lewis酸、质子酸、无机酸酐、分子筛、酸化蒙脱土在催化甘油与环己酮缩合反应中的活性,研究了催化剂结构和性质对环己酮转化率和反应选择性的影响。结果表明,Lewis酸有较高的催化活性和稳定性,而且表现为L酸和B酸两种酸的催化形式。催化剂结构对环己酮转化率和反应选择性的影响为:(1)Lewis酸的构成:对相同阴离子的Lewis酸而言,其阳离子的L酸酸强度越强或水解程度越大,催化活性和2-羟甲基-1,4-二氧杂螺环4,5]癸烷(产物a)的选择性越高;对相同阳离子的Lewis酸而言,其盐酸盐型的催化活性和产物a的选择性要高于硫酸盐型的;(2)水合硫酸盐的催化活性与其煅烧温度有关。催化活性和产物a的选择性最好的Lewis酸为AlCl3。当n(AlCl3)∶n(环己酮)∶n(甘油)=1∶10 000∶15 000,带水剂环己烷加入量为反应物总体积的47%,92℃回流反应2 h,环己酮转化率为97.9%;最终产物中产物a的选择性为97.8%。

Investigation on the Catalysts for Condensation of Cyclohexanone with Glycerol

The condensation of cyclohexanone and glycerol catalyzed by various catalysts was investigated aiming to study the effects of catalyst′s structure and property on the conversion of cyclohexanone and the reaction selectivity.The catalytic activities of Lewis acid,proton acid,inorganic anhydride,zeolite and montmorillonite were compared.The result indicates that the assayed Lewis acids exhibit high catalytic activity and stability in both forms of Lewis and Brnsted acid.The main factors influencing the catalytic activities are as follows.(1)For Lewis acids with same anionic moiety,those containing cationic moieties with stronger Lewis acid intensity or larger hydrolysis equilibrium constant exhibit higher activity and higher selectivity for 2-methylol-1,4-dioxaspiro decane.In addition,the catalytic activity and selectivity of hydrochlorides are higher than those of sulfates if they contain same cationic moieties.(2)The catalytic activity of the hydrated sulfates is significantly influenced by the calcination temperature.Besides,AlCl3 performed the highest catalytic activity and stability among the tested Lewis acids.When the molar ratio of catalyst to reactants was n(AlCl3)∶n(cyclohexanone)∶n(glycerol)=1∶10 000∶15 000,the volume ratio of cyclohexane as refluxing solvent and reactants was 47%,reaction temperature 92 ℃ and reaction time 2 h,a cyclohexanone conversion of 97.9% and a selectivity for 2-methylol-1,4-dioxaspiro decane of 97.8% was achieved.