A review on lignin waste valorization by catalytic pyrolysis: Catalyst, reaction system, and industrial symbiosis mode

The lignin waste from lignocellulose biorefinery limits its green recycling development. Lignin is a kind of natural aromatic polymer with a complex three-dimensional amorphous structure. Catalytic pyrolysis technology has been employed to convert lignin waste into high-grade aromatic compounds, which can realize the full-component refining of biomass. However, the catalytic pyrolysis of lignin has faced problems such as low target product selectivity and poor catalyst stability, which affects the conversion efficiency and economy. This review aims to scope the latest developments the lignin waste valorization by catalytic pyrolysis from the aspects of lignin structure characteristics, catalytic pyrolysis mode, catalyst types, and catalytic pyrolysis reaction system, respectively. The latest aspects of catalyst and catalytic pyrolysis reaction system development in the lignin pyrolysis process have been emphatically analyzed. Based on a critical analysis of the scientific literature, the industrial symbiosis model of cross-industry comprehensive utilization of biorefinery lignin waste with a focus on catalytic pyrolysis technology was proposed for accurately incorporating catalytic pyrolysis technology into the biorefinery system. Finally, several perspectives on designing efficient and commercial application strategies of lignin waste energy utilization are addressed. This review can provide a scientific reference for further research studies on lignin waste residue produced by lignocellulose biorefinery.