Rebuilding the N-doping and O-removal reaction networks during biomass ammonia torrefaction pretreatment in terms of cellulose, hemicellulose, and lignin

Ammonia torrefaction pretreatment (ATP) is a novel approach to realize the synergetic N-doping and O-removal reactions on lignocellulosic biomass, converting biomass into a N-enriched material to produce the N-containing chemicals (NCCs) through fast pyrolysis. In this work, the migration mechanism of N element during biomass ATP and pyrolysis process was revealed from in terms of the biomass pseudo components (hemicellulose, lignin, and cellulose). Higher ATP temperature favored for the doping of N element into biomass through the Maillard reaction. The N content in torrefied hemicellulose was much higher than that of torrefied cellulose and lignin, presenting as pyridinic-N, pyrrolic-N, and ─NH_n groups. Higher ATP and pyrolysis temperature both promoted the formation of the NCCs. For the torrefied hemicellulose, the NHCs were the dominant NCCs, but the amines and nitriles with the nitrogenous straight chains for the torrefied cellulose and lignin.