Nitrogen migration and transformation in chars and tars during co-pyrolysis of cellulose/xylan/lignin with urea formaldehyde

Investigating how cellulose, xylan, and lignin affect nitrogen’s migration and transformation during pyrolysis is valuable, as lignocellulose pyrolysis can markedly alter these processes. This paper studied the co-pyrolysis of cellulose/xylan/lignin with urea formaldehyde (UF) using a thermogravimetric (TG) analyzer to assess their interactions. Furthermore, co-pyrolysis experiments of cellulose/xylan/lignin with UF at different temperatures were conducted in a fixed-bed reactor. TG analysis indicated that UF co-pyrolyzing with cellulose/xylan enhanced lower-temperature reactions, while it inhibited reactions when co-pyrolyzed with lignin. Co-pyrolysis studies showed xylan addition significantly enhanced char nitrogen retention, whereas lignin promoted nitrogen volatilization. Cellulose, xylan, or lignin incorporation yielded chars with more stable heterocyclic-N. Nitrogen preferentially migrated into the tars within a temperature range of 400 °C to 600 °C, and heterocyclic-N synthesis was efficient between 400 °C and 500 °C. The addition of cellulose or xylan significantly affected the transformation of nitrogenous compounds in tars, while lignin exhibited a relatively weaker influence on this process.