Progress in pyrolysis of lignin and its model compounds

Lignin is the second largest renewable biomass resource in the world, thus making full use of lignin is of great significance to the development of our national economy. The lignin pyrolysis has attracted wide attention of scholars due to its advantages, low cost, simple operation and the production of high value-added products. The pyrolysis mechanisms of lignin model compounds (including β-O-4, α- O-4, β-5, etc.) were reviewed, the degree of difficulty of bonds breaking and the difference of products were compared. The characteristics, influence factors and the products distribution of lignin pyrolysis were summarized, the catalytic pyrolysis mechanisms of lignin especially under the action of metal salts and zeolites were expounded. The key control factors and product characteristics of lignin pyrolysis to produce phenolic chemicals and bio-oil were introduced in detail. In view of the problems existing in the technology of lignin pyrolysis, including unclear mechanism, low selectivities of target products and difficulty in product purification, exploring pyrolysis mechanism, developing new catalysts and production processes, and improving economic efficiency were prospected. It provides a theoretical basis for the resource utilization of lignin. © 2019, Chemical Industry Press. All right reserved.