Effect of temperature on product properties and synergies during the co-pyrolysis of paper sludge and corn stover

Abstract

Paper sludge (PS), a by-product of paper mill wastewater treatment, has attracted increasing attention due to the dual nature of resources and pollution. This study focused on investigating the effect of temperature on the product properties and synergies of the co-pyrolysis process involving PS and corn stover (CS) using a fixed bed reactor. The results showed that co-pyrolysis led to an increase in the production of bio-oil, while reducing the formation of char and gases. Notably, the most significant synergistic effect was observed at 600 °C, where the experimental bio-oil yield surpassed the calculated value by 8.9%. At temperatures below 500 °C, ketones, aldehydes, and acids were the predominant products in the co-pyrolysis, which shifted towards phenols and aromatics as the temperature increased. Moreover, a promotion of CO content and an inhibition of CO2 content with temperature were also observed during co-pyrolysis, suggesting that higher temperatures facilitated synergistic decarbonylation. The co-pyrolysis biochar exhibited a higher abundance of carbonyl and alkyl groups compared to the biochar derived from PS pyrolysis, and the synergistic effect at higher temperatures promoted the development of micropores within the co-pyrolysis biochar. These findings emphasize the temperature-dependent nature of the co-pyrolysis process, offering valuable insights into the potential resource utilization of PS and CS wastes.