Catalytic co-pyrolysis of low-density polyethylene and lignin over Cu-modified HZSM-5: Insight with online photoionization mass spectrometry

Abstract

Catalytic pyrolysis of lignocellulosic biomass usually suffers from coking because of its hydrogen-deficient and oxygen-rich nature. The co-feeding of biomass with plastics may enhance product quality. Herein, we studied the catalytic co-pyrolysis of low-density polyethylene (LDPE) and lignin (LG) over HZSM-5 modified with Cu. The effects of Cu valence and feedstock mass ratio on the product distributions were characterized by online photoionization mass spectrometry. Our results show that the addition of Cu limits the formation of aliphatics and promotes the aromatization reaction to produce monocyclic aromatic hydrocarbons (MAHs). The Cu2O/HZSM-5 catalyst exhibits better dehydrogenation activity and promotes the formation of phenolics, while the CuO/HZSM-5 catalyst has a better selectivity for MAHs. In addition, the feedstock mass ratio was also screened, indicating that the highest yield of aromatics was obtained at a mass ratio of 1:3 (LG: LDPE). This work provides new insights into the efficient use of biomass and plastics.