South China University of Technology

Jinxing Long

Xuehui Li

Zhenping Cai

Weijie Zhao

Hongwei Ma

Lefu Wang

Zhangmin Li

Yingwen Li

The invention discloses a method for preparing maleate by selective catalytic oxidation of lignin. The method uses a heteropolyacid functionalized ionic liquid as a catalyst, and an aqueous alcohol solution as a reaction medium to achieve high-efficiency selective catalytic conversion and ring opening oxidation of biomass lignin at a reaction temperature of 110-160&#xb0; C. and an oxygen pressure of 0.5-1.0 MPa for 1-6 h. The selectivity of maleate is higher than 47.83%. The yield and selectivity of a single chemical derived from the depolymerization of lignin in the present invention are much higher than the prior art, and the ionic liquid catalyst exhibits outstanding advantages such as availability of recovery and recycling through simple temperature adjustment; the reaction conditions of the present invention are mild, and the process is green and safe, easy to operate, and available for batch and continuous production. The invention provides a new green way for preparing bulk chemicals like maleate from reproducible raw materials such as lignin.

Method for preparing maleate by selective catalytic oxidation of lignin

The present invention discloses a method for preparing p-hydroxycinnamate by using an ionic liquid for catalytic lignin depolymerization comprising: 1) preparation of a halogen metal-based ionic liquid: preparing the halogen metal-based ionic liquid by reacting an alkylimidazole chloride with a metal chloride by heating the same to 30&#xb0; C. to 80&#xb0; C. with stirring; and 2) catalytic depolymerization of lignin: mixing the halogen metal-based ionic liquid and lignin with an alcohol, and after Nreplacement, heating the solution to 140&#xb0; C. to 200&#xb0; C. and reacting the solution for 4-8 h while stirring to prepare high value-added chemicals with p-hydroxycinnamate as a main product. The present invention has advantages of a simple process, mild conditions, environmental kindness, and high selectivity for a main product. The ionic liquid is simple in preparation, has a good atom economy, and is recyclable. Under optimal conditions, the yield of p-hydroxycinnamate can reach 40-80 mg/g.

Method for preparing p-hydroxycinnamate by using ionic liquid for catalytic lignin depolymerization

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Guangzhou, China

Jinxing Long