稀土改性复合固体超强酸SO_4~(2-)/TiO_2-MoO_3-La_2O_3催化剂催化合成缩醛(酮)

研究了稀土改性复合固体超强酸SO42-/T iO2-M oO3-La2O3催化剂的制备方法,催化剂的适宜制备条件为:n(La3+)∶n(T i4+)=1∶34、M oO3的质量分数25%、硫酸的浸泡浓度0.5mol/L、硫酸浸泡时间24h、焙烧温度450℃、活化时间3h。以SO42-/T iO2-M oO3-La2O3为催化剂,对以乙酰乙酸乙酯、环己酮、丁酮、苯甲醛、正丁醛与二元醇(乙二醇、1,2-丙二醇)为原料合成10种缩醛(酮)的反应条件进行了研究,较系统地研究了醛(酮)与二元醇摩尔比、催化剂用量、反应时间对收率的影响。实验结果表明,在n(醛(酮))∶n(乙二醇(1,2-丙二醇))=1.0∶1.5、催化剂用量占反应物料总质量的0.8%、环己烷为带水剂、反应时间60m in的条件下,10种缩醛(酮)的收率在56.9%~88.2%之间。

Synthesis of Acetals and Ketals over Solid Super Acid Catalyst Modified with Rare Earth Element——SO_4~(2-)/TiO_2-MoO_3-La_2O_3

Solid super acid catalyst modified with rare earth element——SO~(2-)_4/TiO_2-MoO_3-La_2O_3 was prepared.Optimal preparation conditions were:n(La~(3+)) ∶n(Ti~(4+))=1 ∶34,mass fraction of MoO_3 25%,concentration of impregnating H_2SO_4 solution 0.8mol/L,impregnating time 24h,calcination temperature(450℃,)and calcination time 3h.SO~(2-)_4/TiO_2-MoO_3-La_2O_3 was used as catalyst for synthesis of acetals or ketals,namely 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane,2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane,cyclohexanone ethylene ketal,cyclohexanone 1,2-propanediol ketal,butanone ethylene ketal,butanone 1,2-propanediol ketal,2-phenyl-1,3-dioxolane,4-methyl-2-phenyl-1,3-dioxolane,2-propyl-1,3-dioxolane,and 4-methyl-2-propyl-1,3-dioxolane.Effects of(n(aldehyde(ketone))) ∶(n(glycol),)catalyst mass fraction and reaction time on yield of acetals or ketals were investigated.Under optimal reaction conditions:n(aldehyde(ketone)) ∶n(glycol)1.0 ∶1.5,mass fraction of catalyst in reactants 0.8%,reaction time 60min and cyclohexane as water-stripping agent 8mL,yields of 2-methyl-2-ethoxycarbonylmethyl-1,3-dioxolane,2,4-dimethyl-2-ethoxycarbonylmethyl-1,3-dioxolane,cyclohexanone ethylene ketal,cyclohexanone 1,2-propanediol ketal,butanone ethylene ketal,butanone 1,2-propanediol ketal,2-phenyl-1,3-dioxolane,4-methyl-2-phenyl-1,3-dioxolane,2-propyl1,3-dioxolane and 4-methyl-2-propyl-1,3-dioxolane were 71.6%,75.5%,82.6%,82.5%,56.9%,88.2%,73.3%,73.6%,74.1%,and 72.8%,respectively.