Abstract:

Modified-V₂O₅ catalysts，used in the oxidation of isoeugenol with H₂O_2，were prepared by reducing V₂O₅ with glycerol and then impregnating with phthalic acid or disodium phthalate solution. The obtained catalysts were characterized by FT-IR，diffuse reflectance UV-Vis（DR UV-Vis）and XRD. It was found that the reduction-impregnation method can effectively improve their properties by changing the valence state and crystal structure of V₂O₅. Among them，(PVO)-120 catalyst obtained from the reduction of V₂O₅ with glycerol at 120 ℃ and then impregnating with disodium phthalate presented better performance. The effects of promoters such as N,N-dimethylformamide（DMF），DMF amount and reaction time on the oxidation were investigated. 87.3% conversion of isoeugenol and 78.0% yield of vanillin were achieved under the optimal condition，i.e.（PVO）-120 as catalyst in DMF-CH₃COCH₃（20%，volume ratio）when isoeugenol∶H₂O₂ = 1∶2（mole ratio）after 4 h reaction at 20 ℃.

摘要：

V₂O₅经甘油还原，再以邻苯二甲酸或其二钠盐溶液浸渍，制备了改性V₂O₅催化剂用于异丁香酚的过氧化氢氧化。运用FT-IR、紫外可见漫反射光谱（DR UV-Vis）、XRD等对催化剂进行了表征。结果表明，还原-浸渍法可以有效调变V₂O₅的价态与晶体结构从而提升其催化性能，其中以甘油在120 ℃还原V₂O₅所得前体浸渍邻苯二甲酸二钠所得催化剂 (PVO)-120性能较佳。考察了N,N-二甲基甲酰胺（DMF）等助剂、DMF用量和反应时间等对氧化反应的影响。最优反应条件为：以 (PVO)-120为催化剂，以DMF-CH₃COCH₃（20%，体积比）为介质，异丁香酚：H₂O₂=1∶2（摩尔比），20 ℃反应4 h，异丁香酚转化率可达87.3%，香草醛收率达到78.0%。