Yuqiang Zhou,Xixi Zhou,Shuang Ou,Hongwei Zhao,Tongbo Pan,Zhongzhong Qian,Qinglong Xie,Yong Nie
1,3-Propanediol (1,3-PDO) as an important chemical intermediate can be used in the synthesis of polyesters, plasticizers, and surfactants. Catalytic hydration of acrolein to 3-hydroxypropionaldehyde (3-HPA) is a key step for the industrial production of 1,3-PDO from renewable glycerol. However, conventional acid catalytic hydration reactions have the issue of low 3-HPA yield resulting from the trade-off effect between acrolein conversion and 3-HPA selectivity, which is mainly due to the formation of unstable intermediates in the reaction pathway and the high reaction energy barriers. Here, we developed a synergistically catalytic system consisting of proton-donating carboxyl groups as the Brønsted acid sites and amino groups as the Lewis base sites, which was employed in acrolein hydration reaction. Compared with the acid catalytic process, the acrolein conversion significantly increased from 11.9 % to 89.3 % under the acid-base synergistic catalysis, with the 3-HPA selectivity increased from 95.5 % to 97.1 %. Density functional theory (DFT) calculations indicate that the reaction intermediates can be stabilized via the robust C N covalent bonds. Moreover, the energy barrier of the acrolein hydration reaction is reduced from 58.2 to 46.2 kcal/mol, which contributes to the increase in the 3-HPA yield.
Qinglong Xie,Yuqiang Zhou,Yilei Wang,Tongbo Pan,Ying Duan,Shangzhi Yu,Weirong Ji,Yong Nie
Catalytic hydration of acrolein to 3-hydroxypropionaldehyde (3-HPA) is a key step for the chemical production of 1,3-propanediol (1,3-PDO) from renewable glycerol. However, a main issue of low reaction rate and long reaction time exists in the conventional hydration process. Here, we developed a microwave-assisted system for the efficient conversion of acrolein to 3-HPA. Simultaneous cooling method was adopted to maintain continuous microwave irradiation and meanwhile stable temperature during the reaction. The effects of catalyst type, temperature, catalyst loading and microwave power on acrolein conversion and 3-HPA selectivity were examined. Kinetic study showed that microwave irradiation could help for the reduction in activation energy, which led to acceleration in reaction rate during the acrolein hydration process. In addition, the density functional theory (DFT) calculations on the adsorption and reaction behavior of reactants molecules on the catalyst are consistent with the experimental results, which confirm the intensification effect of the microwave field.
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