固体超强酸SO42-/SnO2-Nb2O5的制备及其表征

采用共沸除氯工艺制备SO₄^2-/SnO₂-Nb₂O₅固体超强酸，该方法引入共沸蒸馏，以正丁醇和无水乙醇为溶剂，锡盐醇溶液滴加氨水前除去其中结晶水再除氯离子，免去抽滤除氯步骤，缩短了催化剂制备时间。将制备的SO₄^2-/SnO₂-Nb₂O₅用于催化α-蒎烯的异构化反应，考察催化剂制备条件对催化剂活性的影响，采用FT-IR，XRD，TG-DTA等对催化剂的物化性质进行表征，并与沉淀法、sol-gel法制备的催化剂进行对比。结果表明：催化剂最佳制备条件为Nb₂O₅加入量为SnO₂质量的25%、浸渍液硫酸浓度0.5 mol/L、焙烧温度500 ℃、焙烧时间2 h，将该条件下制备的SO₄^2-/SnO₂-Nb₂O₅应用于催化α-蒎烯异构化反应时，α-蒎烯完全转化，莰烯选择性为66.49%；与沉淀法、sol-gel法相比，相同条件下共沸除氯法制备的催化剂较好。

PREPARATION AND CHARACTERIZATION OF SO42-/SnO2-Nb2O5 SOLID SUPERACID CATALYST

SO42/SnO2-Nb2O5 solid superacid catalyst was prepared by azeotropic dechlorination method,using n-butanol and anhydrous alcohol as solvents,a filtration step could be omitted,and thus the catalyst preparation time was much shortened.The prepared catalyst was characterized by XRD,FT-IR,TG-DTA and its catalytic performance was evaluated using isomerization of α-pinene as probe reaction.Test results showed that the optimum preparation conditions of SO42/SnO2-Nb2O5 solid superacid catalyst were as follows: a Nb2O5/SnO 2 mass ratio of 0.25,the concentration of impregnating sulfuric acid solution was 0.50 mol/L and calcined at 500 ℃ for 2.0 h;catalyst prepared under such conditions exhibited good catalytic performance in isomerization of α-pinene,the conversion of α-pinene and selectivity of camphene was 100% and 66.49%,respectively.Compared with other preparation methods,such as precipitation and sol-gel methods,catalyst prepared by azeotropic dechlorination method was better.