Method for preparing aromatic compound by catalytic hydrocracking of lignin

Abstract

The invention relates to a method for preparing an aromatic compound by direct catalytic cracking of lignin. Under the combined action of a catalyst and a solvent, industrial lignins such as natural lignin, sodium lignin sulfonate, alkali lignin and dealkalized lignin are used as raw materials and are selectively cracked into the aromatic compound derived from C6-C9 phenolic group, guaiacol group or syringyl through the catalytic process. The conversion rate of the raw materials reaches over 50%, and the guaiacol group and the syringyl aromatic compound account for over 90% in a cracking product. The method has the characteristics of cheap raw materials, high conversion rate, high yield of the aromatic compound and mild reaction condition.

Description

technical field [0001] The invention relates to a method for preparing aromatic compounds by catalyzing lignin hydrocracking of biomass resources, in particular to a method for generating aromatic compounds such as phenol, guaiacol or syringyl by catalyzing lignin. Background technique [0002] The continuous development and consumption of petroleum and other fossil resources have resulted in shortages of energy chemicals and a series of environmental problems. The development and utilization of new recyclable resource routes has become an inevitable trend of social development. Biomass is a recyclable natural resource with a wide range of sources and abundant reserves in nature. It is one of the renewable resources with great potential to replace fossil resources such as petroleum. Aromatic compounds have important applications in human production practices. For example, benzene, phenol and their derivatives are not only widely used bulk chemicals, but also important inte...

AI Technical Summary

Problems solved by technology

The reaction conditions of the process are harsh, and the temperature and pressure are too high

Chinese patent (CN 1201778A) describes a method for obtaining syringaldehyde and vanillin by oxidizing alkali lignin, but the products obtained by this method are other chemicals, and it is impossible to obtain alkyl-substituted guaiacols and lilac Basic aromatic compound products

[0007] 1. Lignin itself is a high polymer, which is usually connected with the sugar group of plant hemicellulose by chemical bonds, which is not easy to separate and purify. At the same time, the curled polymer chain of lignin makes it difficult to carry out the catalytic reaction and presents a chemical reaction inert;

[0008] 2. The structural characteristics of lignin increase the energy consumption of the conversion process, the reaction conditions are harsh, and the conversion rate of reaction products is low;

[0009] 3. The conversion of lignin often causes excessive hydrogenation of the benzene ring on the chain, so more hydrogen sources are needed, and the atom economy is low

[0010] 4. At present, it is reported in the literature that the catalysts used for lignin hydrogenation are noble metal catalysts such as Pt and Ru, and there is no cheap Ni catalyst for hydrocracking lignin

Ni-based catalysts are cheap hydrocracking catalysts, but the reaction temperature is usually above 350°C and the energy consumption is high

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