Study on α-pinene Isomerization Catalyzed by SO_4~(2-)/ZrO_2 Solid Superacid

SO~(2-)_4/ZrO_2 type of solid superacids was prepared and then used as the high-activity catalysts of α-pinene isomerization.The products of isomerization reaction were identified by using GC-MS.In the isomerization reaction,the main product is camphene,and by-products are α-terpinene and tricyclene.The effects of conditions for preparation of (SO~(2-)_4/ZrO_2) catalysts,such as concentration of H_2SO_4,calcination temperature with respect to its catalytic activity,were investigated.The results showed that the optimum conditions for the preparation of SO~(2-)_4/ZrO_2 catalysts were as follows:calcinations temperature was 650 ℃,and the H_2SO_4 concentration used to treat the catalyst was 0.5～1.0 mol/L.At these conditions,the main factors affecting the reaction were investigated in the work.The optimum conditions for α-pinene isomerization reaction were as follows:reaction time was 1～3 h,isomerization temperature was(130±2)℃,and the ratio of solid superacids(W/W) to α-pinene 3%～4%.Under these conditions,the α-pinene conversion was 96.4%,and the camphene selectivity was (49.7%).Furthemore,the effects of storage time of the catalysts on the reaction were discussed,and the regeneration experiments of catalysts were carried out.