Method for preparing methyl levulinate in near-critical methanol by plant polysaccharide alcoholysis one-pot method

Abstract

The invention discloses a method for preparing methyl levulinate in near-critical methanol by a plant polysaccharide alcoholysis on-pot method. The method comprises the following steps: 1) adding methanol, plant polysaccharide and acid catalyst in a high pressure reaction kettle, wherein the mass concentration of the plant polysaccharide is between 10 and 120g / L, and the molar concentration of the acid catalyst is between 0.01 and 0.06 mol / L, replacing air in the kettle by nitrogen after the kettle is closed, and starting stirring; 2) heating the materials to the temperature of between 160 and 200 DEG C for alcoholysis for 1 to 10 hours; 3) cooling the materials to the room temperature after the alcoholysis is completed, and opening an exhaust valve to collect dimethyl ether; and 4) regulating pH value of the alcoholysis solution to be neutral, distilling the solution under the normal pressure to remove low-boiling products and solvent, and distilling the solution under reduced pressure to obtain the methyl levulinate. The method has the advantages of biomass raw materials, abundant resources and simple and green one-pot preparation process, and has important industrial application value.

Description

technical field [0001] The invention relates to a new method for resource utilization of biomass, in particular to a method for preparing methyl levulinate in a one-pot method of alcoholysis of plant polysaccharides in near-critical methanol. Background technique [0002] Plant polysaccharides, also known as plant polysaccharides, are polysaccharides produced by plant cell metabolism with a degree of polymerization of more than 10. Generally, plant polysaccharides are composed of more than 100 or even thousands of monosaccharide groups. Plant polysaccharides are divided into two categories according to their functions in plants: one is to form the support tissue of plants, such as cellulose, which accounts for more than 50% of the carbon content in the plant world, and produces about 1011 tons of cellulose every year; the other is the storage of plants. Nutrients can be hydrolyzed by enzymes to release simple sugars to supply energy, such as starch. With the decrease of pet...

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Problems solved by technology

Though the methyl esterification process yield of levulinic acid is high (80~90%), production cost is low, but there are many side reactions in the preparation process of levulinic acid, a large amount of by-products and solid wastes that are easy to form, seriously affect The mass transfer, heat transfer and product purification and separation of the reaction; at the same time, the boiling point of levulinic acid is high [139-140°C (1kPa)], and the distillation and extraction from the water phase requires high energy consumption, and the cost of distillation and purification accounts for 65% of the total operating cost. %, these cause the production cost of levulinic acid to remain high, which affects the development of its downstream products

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