NO and N2O formation during nitrogen model compound (amino acids) combustion: Role of cellulose and lignin

Amino acids were widely used as model compounds to investigate the nitrogen chemistry during biomass thermal utilization. In this work, the formation characteristics of NO and N2O during combustion of five amino acids (glycine, glutamic acid, proline, aspartic acid and histidine) were investigated in a fixed bed reactor. The results show that N2O yield is comparable to or even much higher than that of NO during individual amino acid combustion. The biomass main components (cellulose and lignin) are of great influence on nitrogen conversion, which are highly related to amino acid type. For glycine and aspartic acid, co-combustion with cellulose and lignin promotes the fuel-N conversion to NO while the N2O formation is greatly inhibited. In contrast, both NO and N2O formation are promoted by co-combustion proline with biomass components. Nevertheless, the ratio of N2O/NO decreased with the addition of cellulose and lignin. The nitrogen conversion during char oxidation seems to be dominated by the char-N content, and the char with high N content is more prone to produce N2O other than NO. The results may provide some new insights on the fundamental mechanism of fuel-N conversion during biomass combustion.