改性V_2O_5催化过氧化氢氧化异丁香酚制香草醛

Oxidation of isoeugenol to vanillin with hydrogen peroxide catalyzed by modified-V_2O_5

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%。

Modified-V2O5 catalysts,used in the oxidation of isoeugenol with H2O2,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 ℃.