Co-pyrolysis of chitin with nitrogen carriers: Kinetics, product characterization and bio-oil analysis

Abstract

Considering the depletion of fossil fuels and the cumbersome traditional synthesis process of chemical compounds containing nitrogen, there is increased interest in direct production of nitrogenous compounds (bio-oil) from nitrogen-rich pyrolysis of biomass. In this study, a new strategy for the preparation of both nitrogen-rich bio-oil and biochar by co-pyrolysis of chitin and nitrogen carriers was proposed. Four different nitrogen carriers (urea, ammonium acetate, glutamate, and polyurethane) were selected and the thermal behavior of the mixtures as well as the synergistic competitive effects between the pyrolytic volatiles were characterized. Simultaneously, the properties of the co-pyrolysis products and the distribution of the main components in bio-oil were analyzed. The results showed that co-pyrolysis of chitin and nitrogen carriers had a synergistic effect. Glutamate had the most significant inhibitory effect on volatile gases, while only polyurethane promoted the release of volatile gases. Compared to the pyrolysis of chitin alone, the addition of urea, ammonium acetate and polyurethane effectively reduced the activation energy of the reaction. The addition of nitrogen carriers promoted the production of amines. Co-pyrolysis of urea and glutamate (40%) increased the content of nitrogenous compounds by 14.84% and 3.41%, respectively. However, the addition of ammonium acetate and polyurethane hindered the conversion of oxygenated compounds to nitrogen-containing compounds. In addition, the formation pathways of chitin pyrolysis and co-pyrolysis products were summarized. This work expanded the boundaries of high-value utilization of chitin.