Carboxylation of Toluene with CO2 over Dimeric AlCl3 Immobilized on Alumina

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• 作者：Miaofei Gu ; Zhenmin Cheng
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2014
• 出版时间：June 18, 2014
• 年：2014
• 卷：53
• 期：24
• 页码：9992-9998
• 全文大小：348K
• 年卷期：v.53,no.24(June 18, 2014)
• ISSN：1520-5045

文摘

Carboxylation of toluene by CO₂ over AlCl₃ is providing a new approach for CO₂ transformation as well as an improved synthetic method of p-toluic acid with less byproducts under mild condition. To prevent decomposition and corrosion of AlCl₃ powder, AlCl₃ was immobilized over 纬-Al₂O₃ support through reaction between dimer Al₂Cl₆ vapor and hydroxyl groups at the 纬-Al₂O₃ surface, and a high loading of AlCl_x (x = 2.5) up to 72.36 wt % was obtained. The composition of immobilized 鈭扥鈭扐l₂Cl₅ group was detected by HRTEM/EDS and the structure was authenticated to be the same as that of Al₂Cl₆ by ²⁷Al MAS NMR. The Al valence in 鈭扥鈥揂l₂Cl₅ was calculated to be 1.584, which is approximately the same as that in Al₂Cl₆. The above features of 鈭扥鈥揂l₂Cl₅ guaranteed a high CO₂ activation capacity in direct carboxylation of toluene with an isolated p-toluic acid yield of 73.34% with respect to AlCl₃, which approaches that obtained by AlCl₃ powder. Therefore, this work provides a more feasible way for carboxylation by CO₂ in overcoming the instability of AlCl₃ powder in the presence of moisture.