Fast co-pyrolysis characteristics of high-alkali coal and polyethylene using infrared rapid heating

Optimizing secondary reactions using infrared-fast pyrolysis has proved beneficial for investigating the co-pyrolysis behavior. In this study, co-pyrolysis of high-alkali coal (PC) and polyethylene at different temperatures, co-pyrolysis of polyethylene with demineralized coal (DP), and pyrolysis of raw high-alkali coal (RC) and demineralized coal (DC) were conducted in an infrared heating reactor. The results show that the co-pyrolysis promoted the formation of tar and the highest tar yield was 16.16% at 700 °C, and the PC tar yield was higher than that of RC, DC at 500 °C with 7.51% and 5.99% respectively. The tar yields of DP and PC were 7.49% and 11.80%, respectively, and the later had a slightly higher tar yield due to the interaction with AAEM. The addition of PE coupled infrared rapid heating can efficiently reduce the nitrogen and chlorine-containing fractions while increasing the content of long-chain alkanols and linear hydrocarbons. The content of organochlorines decreased from 2.95% at 500 °C to 1.00% at 800 °C. Alkanol and linear hydrocarbons have the highest content in the co-pyrolysis tar, with the total highest content of 61.56% at 600 °C. •Co-pyrolysis of PE and high-alkali coal was employed via infrared heating.•Addition of polyethylene increases long-chain alkanols and hydrocarbons in tar.•Inherent AAEMs intensify the decomposition of phenols and condensation of ketones.•Infrared heating coupled with co-pyrolysis can reduce heteroatom compounds in tar.