Effects of temperature and urea concentration on nitrogen-rich pyrolysis: Pyrolysis behavior and product distribution in bio-oil

Nitrogen-rich pyrolysis is an important means of biomass utilization. In this paper, the effects of urea concentration and pyrolysis temperature on the composition of various nitrogen- and oxygen-containing compounds in bio-oil produced during the pyrolysis of pine powder (PP) were studied. The results showed that A-type (a benzene ring with one methoxy group) and B-type (a benzene ring with two methoxy groups) phenols were only detected in the bio-oil derived from conventional biomass pyrolysis. After nitrogen-rich pyrolysis, the total phenolic content in the bio-oil increased significantly, and all four types of phenols (A, B, C (a benzene ring featuring an alkyl group that is not a methoxy group), and D (other types of phenols)) were detected. In addition, the aldehyde and linear chain ketone contents in the bio-oil significantly decreased after nitrogen-rich pyrolysis compared to after conventional biomass pyrolysis. When the urea concentration was 10 wt%, only cyclic ketones were detected in the bio-oil. Furthermore, the content of nitrogenous heterocyclic compounds in the bio-oil significantly increased after nitrogen-rich pyrolysis when the urea concentration increased from 5 wt% to 10 wt%, with pyridine being the most abundantly produced. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

This study investigates the effects of urea concentration and pyrolysis temperature on the composition of bio-oil. The results demonstrate that nitrogen-rich pyrolysis increases the phenolic content, decreases the aldehyde and ketone content, and enhances the production of nitrogenous heterocyclic compounds.