偏钨酸铵柱撑水滑石上邻苯二酚与甲醇的O-甲基化反应

Vapour-phase O-methylation of catechol with methanol over ammonium metatungstate exchanged hydrotalcites

为提高水滑石催化剂在邻苯二酚与甲醇的气固相烷基化反应中的性能,将偏钨酸铵(AMT)阴离子交换到水滑石层间,采用XRD、FT-IR以及异丙醇脱水-脱氢探针反应等表征手段和方法研究了交换后水滑石的结构和酸碱性质,并将交换前后的水滑石用于邻苯二酚与甲醇气固相合成愈创木酚的反应中.结果表明:AMT阴离子代替NO3-进入到水滑石层间;NO3-柱撑水滑石本身对邻苯二酚与甲醇的气固相反应没有活性,而用AMT交换后水滑石对目标反应的活性明显提高,且催化活性随着层板阳离子种类和比例的不同有较明显的差别,其中AMT-Mg2Al和AMT-Mg1.5Al催化剂表现出了较好的催化性能,邻苯二酚转化率为75%,此时愈创木酚选择性为90%.该催化剂上存在的弱B酸-碱中心对目标反应更有利.

To improve the catalytic performance of catechol with methanol over hydrotalcites catalysts, hydrotalicites were prepared by coprecipitation method and were further anion-exchanged to incorporate ammonium metatungstate in the interlayer domain. The resulting materials were characterized using classical techniques like XRD, FT-IR, and dehydration-dehydrogenation of isopropanol test reaction. Vapour-phase O- methylation of catechol with methanol was investigated over the ammonium metatungstate exchanged hydrotalicites. Results of XRD and IR demonstrate that ammonium metatungstate anions are successfully exchanged into the interlayer domain. The NO3 -hydrotalictes are of catalytic inactivity. The catalytic activity increases obviously when the ammonium metatungste anions are exchanged into the interlayer domain. And the catalytic performance of catechol with methanol varies with the kind of ion and the ion proportion. The conversion of catechol is relatively high （75%） by using AMT-Mg2Al and AMT-Mg1.5Al as catalysts, and the selectivity of guaiacol is 90%. The weak Bronsted acid-base characteristics of the catalysts are favourable to the title reaction.