1,3-丙二醇的化学法合成路线及催化剂研究进展

Recent advances in reaction routes and catalysts for chemical synthesis of1,3-propanediol

  • 摘要: 1,3-丙二醇是一种重要的化工原料,商业应用前景广阔,但目前依然面临生产成本较高的问题。高效且绿色的合成工艺及催化剂的开发是实现1,3-丙二醇低成本、规模化生产的关键。本工作综述了1,3-丙二醇的化学法合成路线,包括丙烯醛水合氢化法、环氧乙烷羰基化法、环氧乙烷氢酯基化法、甘油氢解法、甲醛和乙醛缩合法、丙二酸二烷基酯加氢法等,针对不同路线中影响催化剂活性和选择性的因素及其原因进行了较为详细的阐述,有望为新型高效的多相催化剂的开发提供科学参考。

     

    Abstract: 1,3-propanediol (1,3-PDO) is an important chemical raw material with broad commercial applications in the industrial sector including the polymers, pharmaceuticals, daily chemicals, and food industries. Owing to its fast-growing demand as a monomer in the production of biodegradable polyesters such as polytrimethylene terephthalate (PTT), synthesis of 1,3-PDO through more efficient and greener routes has attracted considerable attention in recent years. However, the production of 1,3-PDO still faces the challenge of high costs. Compared to the biological method which can be operated under mild conditions, the chemical synthesis routes are still popularly applied all over the world. The key to achieving low-cost and large-scale production of 1,3-PDO via chemical synthesis methods lies in the development of efficient and environmental-friendly catalytic processes and catalysts. In this review, we provide a comprehensive overview of the chemical synthesis routes for 1,3-PDO production, including hydration-hydrogenation of acrolein, carbonylation of ethylene oxide, hydroesterification of ethylene oxide, hydrogenolysis of glycerol, condensation of formaldehyde and acetaldehyde, as well as hydrogenation of dialkyl malonate. Specifically, the reaction conditions for the hydration-hydrogenation of acrolein are generally mild. However, this route poses a high safety risk due to the nature of its raw materials, and low hydration efficiency which always cause a high energy consumption for the whole process. For carbonylation of ethylene oxide, in addition to the use of toxic ligands, the formation of unstable 3-hydroxypropanal intermediates and their subsequent side reactions significantly impact the yield of 1,3-PDO. By contrast, hydroesterification of ethylene oxide does not generate 3-hydroxypropanal. However, more efforts should be devoted to the improvement in terms of catalyst recycling in homogeneous systems or selectivity in Cu-based heterogeneous catalysts during the hydrogenation of methyl 3-hydroxypropionate. Hydrogenolysis of biomass-derived glycerol is one of the promising green routes for the future production of 1,3-PDO. Reducing the cost of Pt-based catalysts by increasing the utilization of noble metal atoms while maintaining their performance determines the feasibility of this route. Condensation of formaldehyde and acetaldehyde is less studied at present, necessitating the development of efficient catalysts under mild conditions to enhance their competitiveness. Dialkyl malonate can be produced from malic acid, a bio-based platform compound, making the hydrogenation of dialkyl malonate a potential green synthetic route for 1,3-PDO. The currently employed Cu-based catalysts are typically accompanied by using elevated temperatures and high hydrogen pressures, thereby resulting in the occurrence of side reactions such as decarboxylation and hydrolysis, which impose limitations on their industrial applications. The development of catalysts with high catalytic activity and products selectivity under mild conditions is of great significance for the hydrogenation of dialkyl malonate to 1,3-PDO. Among above-mentioned chemical synthesis routes, the use of bio-based feedstocks for the production of 1,3-PDO aligns with the imperative of sustainable development and deserves further investigation that combines the synthesis of new or better catalysts and the design of more efficient process. In summary, in this review article, the factors affecting the activity and selectivity of the catalysts in different chemical synthesis routes along with their underlying causes are discussed in detail, which are projected to provide new insights in developing improved catalytic systems for the production of 1,3-PDO.

     

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