Abstract
Clarifying the structure, category, and content of nitrogen-containing compounds in coal tar is not only the key to directional regulation of pyrolysis processes, but also one of the needs for refined utilization of coal resources. developing simple, direct, and efficient structural analysis methods for nitrogen-containing compounds is very important for further investigation of nitrogen-rich tar. In this study, nitrogen-rich tar was obtained by co-pyrolysis through low rank coal and NH4Cl; meanwhile, 15NH4Cl were selected as the NMR signal enhancement for the structural characteristics research. The results indicated that the nitrogen-rich tar primarily consisted of substituted aromatic amines, aliphatic amines, piperidine, pyrrole, pyridine, quinoline, and other nitrogen-containing compounds. Various nitrogen-containing compounds exhibit distinct functional properties. Compared with GCMS analysis method, 1H-15N HMBC NMR provides more structural information about nitrogen-containing compounds, especially the substitution characteristics of aromatic amines; at the same time, 1H-15N HMBC provides very “clean” 2D spectrum compared to 1H-13C HSQC simultaneously.
Data availability
In this article, the NIST08 database was used for matching during the GC/MS analysis of coal tar, and all other data are included in the manuscript.
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Funding
This research was funded by the National Natural Science Fundamental Project (No. U24A20552, 32202164), Scientific Research Program Funded by Shaanxi Provincial Education Department (No.21JK0772), Xi’an Science and Technology Plan Project (No. 23NYGG-0068) for the financial support.
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Y.Z., F.C. and Z.L. conceived the project and designed the research. P.C., B.S. and G.L. performed NMR experiment. N.W., H.T. and A.Z. provided co-pyrolysis of rich oil coal. G.S. and A.Z. provided GC-MS analysis. X.H. and B.S carried out statistical analyses and structural analysis. P.C., Q.W. wrote and revised the manuscript.
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Zhang, Y., Chen, P., Shi, G. et al. Study on the structural characteristics of nitrogen-containing compounds in co-pyrolysis tar of low rank coal using 1H-15N HMBC analysis. Sci Rep (2026). https://doi.org/10.1038/s41598-026-41962-w
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DOI: https://doi.org/10.1038/s41598-026-41962-w
