Synergistic effect of nitrogen-rich pyrolysis of three components and nitrogen transformation mechanism

Abstract

The synergistic mechanism of nitrogen-containing chemicals (NCCs) production was explored from the co-pyrolysis of corn cob and the three major biomass components (cellulose, xylan, and lignin) with urea. Compared to individual pyrolysis, the stability of co-pyrolysis oil was significantly enhanced. The three components showed a synergistic effect during co-pyrolysis. The phenolic compounds generated from lignin interacted with the pyran compounds produced from cellulose or xylan. Especially in the presence of urea, this cross-reaction enhanced the formation of nitrogen-containing heterocycles (NHCs). At 500 ℃, the highest yield of NCCs was observed in the co-pyrolysis oil of corn cob and urea, reaching 47.6 wt%. The NHCs exhibited a selectivity of up to 96.9 wt%. The high concentration of urea promoted the pyrolysis of hemicellulose and cellulose, inhibiting the reaction between cellulose-derived products and free amines to form amines. FT-IR analysis of the char revealed that the addition of urea promoted the decomposition of corn cob, enhancing C–H bond breakdown and dehydrogenation reactions. Finally, a potential formation mechanism for the primary NHCs during the co-pyrolysis of corn cob and urea was proposed. The findings of this paper provide theoretical support for the production of NCCs from biomass through the synergistic interaction of its three components.