纳米复合S2O8^2-／SnO2-TiO2催化α-蒎烯异构反应

Isomerization of α-Pinene Catalyzed by Nanometer Composite S_2O_8^(2-)/SnO_2-TiO_2 Solid Superacid

采用溶胶-凝胶法制备了新型纳米复合S2O82-/SnO2-TiO2固体超强酸催化剂,用XRD、TEM、FT-IR和BET比表面测定技术对其结构进行了表征。结果显示,所得复合催化剂颗粒为圆球形,粒径为15～20nm,且粒度均匀,具有较好的分散性;S2O82-附着于SnO2-TiO2表面形成强酸中心;SnO2的引入明显增大了催化剂的比表面积。首次将纳米复合S2O82-/SnO2-TiO2用于催化α-蒎烯异构化反应。该催化剂具有较好的催化活性和选择性,异构化反应的主产物是莰烯,副产物是苧烯、异松油烯、三环烯等。与单一型S2O82-/TiO2比较,该催化剂能有效降低异构反应体系温度20～30℃。在适宜的工艺条件下,α-蒎烯的转化率为98%以上,莰烯的选择性达到63%。

Nanometer composite S2O8^2-/SnO2-TiO2 , a novel solid superacid, was prepared by sol-gel method and its structure was characterized by XRD, TEM, FT-IR and BET surface area measurement. The composite S2O8^2-/SnO2-TiO2 had a narrow particle size distribution with an average diameter of about 15 -20 nm. S2O8^2- was attached on the surface of SnO2-TiO2 so that its strong acid sites were formed. The surface area of the catalyst was obviously increased after the incorporation of SnO2. Nanometer composite S2O8^2-/SnO2-TiO2 was used as a catalyst in α-pinene isomerization. The experimental results showed that the catalyst had better catalytic activity and selectivity. The main product of the isomerization reaction was camphene, and the byproducts were limonene, terpinolene and tricyclene etc. Compared with ordinary S2O8^2-/TiO2, the composite catalyst can lower the reaction temperature by 20 - 30℃ for the isomerization. Under suitable conditions, the conversion of α-pinene reached 98% and the selectivity of camphene reached 63%.