Peng Liu,Yuanyuan Zhang,Tieying Pan,Dexiang Zhang,Lishi Chen,Changrong Sun
Coal conversion to material or chemical by pyrolysis is the main methods for achieving carbon neutrality. To predict correct pyrolysis behavior, accurately quantifying carbon structural types of complex coal discussed in this study is significative. Carbon structural types in coal based on 13 C NMR Cp/MAS TOSS spectra were accurately quantified by coupling standard curve and peak-fitting method to reduce nuclear overhauser effect (NOE). The H/C atomic ratio and aromaticity is used to verify the accuracy of this method. The pyrolysis behavior was predicted by pyrolysis Gas Chromatography-Mass Spectrometer (Py-GC-MS), thermogravimetric analysis (TG), and fix-bed slow pyrolysis according to correction carbon structure. The results show that the H/C atomic ratio calculated by correction carbon structure is agreed with that from ultimate analysis, as well as aromaticity. Their correction relative deviations are below 10%, farther lower than experimental value, increasing with the increment of C daf %. The correction carbon structure evolution during pyrolysis is coincided with general conclusion and Py-GC-MS analysis. The mono-aromatics and phenolics are evaluated by correction carbon structure. It is significantly fundamental study for carbon material to chemicals from micro-angle. These results are also a guide for accurate calculation and simulations of quantum chemistry.
Hydrothermal humification provides a rapid and selective strategy for synthesizing artificial humic acid (HA) from lignocellulosic biomass. However, conventional single-stage processes are often limited by low product yields and incomplete biomass conversion. Here, we engineer the conversion pathway by adopting a sequential acid-alkaline hydrothermal process that promotes staged transformation of biomass components. The method achieved a significantly enhanced HA yield of 34.4 ± 1.7 %, which corresponded to a 2.6–17.4-fold increase over traditional approaches. The resulting HA exhibited higher quality compared with conventional hydrothermal HA and even natural HA, as reflected by its high degree of aromaticity (C-C sp 2 content of 70.2 %) and enhanced redox functionality. Mechanistic analyses (UHPLC-ESI-MS, XPS) showed that the acid stage drives dehydration/condensation of carbohydrate derivatives with lignin fragments to form furan-rich humin-lignin complexes, whereas the alkaline stage induces saponification and nucleophilic substitution, depolymerizing these complexes and releasing phenolic, furanic, and cyclopentanone intermediates. These reactive species polymerize and undergo colloidal self-assembly to reconstruct a highly aromatic HA carbon skeleton. A techno-economic analysis indicated the industrial feasibility of the process, with a projected output of 10.5 tons/day and an estimated daily profit of 118,071 CNY. Overall, this work demonstrated the technical and economic potential of a rationally engineered two-stage hydrothermal pathway for sustainable, large-scale HA production.
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