Anning Zhou

To investigate the synergistic effects between oil-rich coal and nitrogen-rich solid waste during co-pyrolysis and their influence on the formation of value-added nitrogen-containing (N-containing) compounds, oil-rich Hongliulin coal and waste leather were subjected to individual and co-pyrolysis at 300–600 °C. Waste leather was selected for its collagen-derived nitrogen-rich characteristics and potential for resource utilization. X-ray Photoelectron Spectroscopy (XPS) revealed distinct N 1s signals in the co-pyrolysis tar, indicating enhanced nitrogen retention in liquid-phase products. Pyrrolic-N identified as the dominant nitrogen species, accounting for 48.76% of the total fitted N 1s peak area, followed by amide/amine-N (29.07%) and pyridinic-N (22.17%). GC-MS analysis and co-pyrolysis resulted in the detection of 10 additional nitrogen-containing compounds that were absent from the individual pyrolysis products, including several high-value compounds. The greatest number of these newly detected nitrogen-containing compounds was observed at 500 °C, suggesting that nitrogen from leather was not entirely released directly but was also incorporated into liquid-phase organic products. To further evaluate the contribution of different nitrogen-containing structural units in leather, amino acids, the major nitrogen-containing constituents of leather, were employed as model compounds. Their structure significantly influenced nitrogen transformation and product distribution. Non-heterocyclic amino acids mainly generated simple N-containing compounds, such as nitriles and amides, whereas amino acids containing cyclic imine structures, particularly proline, preferentially formed aromatic nitrogen-containing heterocyclic compounds. The results suggest that amino acids and short peptide intermediates derived from collagen decomposition are important precursors for N-containing compounds within the co-pyrolytic tar, while coal-derived active hydrogen and aromatic fragments facilitate their stabilization and transformation. Our research provides a fundamental understanding of the synergistic conversion between coal-derived carbon and nitrogen-rich solid waste, offering a potential pathway for producing value-added nitrogen-containing heterocycles, which play important roles in pharmaceuticals and fine chemicals.

Lignin pyrolysis is a pivotal route for biomass valorization, yet the intricate radical reaction network involved results in ambiguous hydrogen/oxygen transfer pathways and product formation mechanisms, severely impeding precise control over directed conversion processes. This study employed a combination of multi-isotope tracing techniques and GC-MS analysis to elucidate the formation mechanisms of four phenolic products during the 500 °C hydrothermal pyrolysis of dealkaline lignin. Experiments using D₂O and H₂¹⁸O revealed that the M + 2 signal was predominantly derived from double deuterium substitution, with an abundance difference spanning 13–81 folds. Phenol exhibited the highest M + 1 abundance (3.947) due to the full exposure of its exchangeable hydrogen sites, while its M + 2 abundance ranked second only to that of 2-methylphenol. For 2-methylphenol, the hyperconjugation effect of the ortho-methyl group activated the phenolic structure, leading to the highest M + 2 abundance among all products (M + 2/M + 1 = 2.3). In contrast, 3-methylphenol showed relatively low abundances (M + 2/M + 1 = 1.67) because the meta-methyl group lacked activating effects and introduced steric hindrance. For guaiacol, the steric hindrance of the methoxy group completely overshadowed its electronic activation effect, resulting in the lowest M + 2 abundance (1.545). CD₃OD tracing experiments and the absence of detectable M + 3 peaks confirmed that the methyl groups in 2-methylphenol and 3-methylphenol were entirely endogenous to the structural units of lignin itself. By precisely tracking the migration pathways of hydrogen and oxygen, this study revealed that hydrogen transfer dominated the pyrolysis process, while oxygen transfer was hindered and methyl groups exhibited endogenous characteristics. These findings establish a mechanistic foundation for designing efficient catalysts tailored to lignin pyrolysis and for rationally steering product selectivity.

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 NH ₄ Cl; meanwhile, ¹⁵ NH ₄ Cl 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, ¹ H- ¹⁵ N HMBC NMR provides more structural information about nitrogen-containing compounds, especially the substitution characteristics of aromatic amines; at the same time, ¹ H- ¹⁵ N HMBC provides very “clean” 2D spectrum compared to ¹ H- ¹³ C HSQC simultaneously.

The solid oxide direct carbon fuel cell (SO–DCFC) is a vital future technology for producing high-efficiency and environmentally friendly electricity. To improve the performance of SO–DCFC, it is required to examine the optimal operation condition selection and anode reaction process optimization. The DCFC reaction model is derived from the anode Boudouard reaction in this study. Electrochemical reaction dynamics, mass transfer, and electrode processes are incorporated into the model. Higher Boudouard reaction rate, gasification rate, and power density of anode carbon were discovered to impact the performance of fuel cells directly. In addition, simulation provides the CO concentration and current density distribution under different output voltage settings, which can be used to assess the performance and give a basis for the best design of DCFC.

The comprehensive quality enhancement and grading of coal are crucial methods for unlocking the high value-added and low-carbon utilization of coal resources. In this work, the influence of oily bubbles on the flotation of Shendong Jurassic vitrinite-rich coal and inertinite-rich coal was studied via flotation tests, Fourier transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), contact angle detection, and induction time measurements. FT-IR and XPS analyses demonstrated that the surface of inertinite-rich coal contains more hydrophilic oxygen-containing functional groups. Contact angle and induction time measurements showed that the vitrinite-rich coal is more hydrophobic than inertinite-rich coal, and that for both air and oily bubbles, the induction time on the surface of vitrinite-rich coal is shorter than that on the surface of inertinite-rich coal. In addition, rather remarkably, the induction times for both vitrinite-rich coal and inertinite-rich coal are significantly reduced by oily bubbles. Finally, a better flotation performance for oily bubble flotation of vitrinite-rich coal and inertinite-rich coal was found. It appears that oily bubble flotation is an efficient method for enhancing the recovery of vitrinite-rich coal and inertinite-rich coal.

The gasification kinetics of semi-coke are an important research topic in the gasification process of semi-coke. The evolution of the pore structure is one of the most important factors affecting the gasification rate of semi-coke. In this paper, the pore fractal growth model was established based on the principle of pore fractal growth and the Sierpinski sponge structure. Three kinds of semi-coke raw materials were used to prepare porous carbon with different degrees of gasification. Combined with the TG curves of raw materials, the gasification kinetics based on the fractal model were verified. The curves of the gasification reaction rate and the specific surface area as a function of carbon conversion were consistent with the random pore model and experimental data, which verified the feasibility of the model. The pore fractal dynamic model could predict the change in the pore structure with carbon conversion during semi-coke gasification, so as to reveal the kinetic law of carbon gasification.

This study examined the incompatibility of high-intensity conditioning (HIC) conditions required for fine and coarse coal particles. The effects of speed and time of stirring on the recovery of coarse and fine particles were investigated by using three different flotation processes. The results showed that the coarse particle recovery of surface cleaning (SC) flotation reached the maximum value of 69.71% at the stirring condition combination of ‘1400 rpm +2 min.’ However, the coarse particle recovery reached the maximum value of ~69.37% at a stirring condition combination of ‘1600 rpm +3 min’ or ‘2000 rpm +2 min’ in HIC flotation. Achieving the same coarse particle recovery, SC flotation consumes less energy than HIC flotation. The maximum recovery of fine particle 65.37% was achieved at a stirring condition combination of ‘1600 rpm +2 min’ in HIC flotation. SC failed to promote the recovery of fine particles and even produced some negative effects in some cases. Fine particles consume less energy than coarse particles with respect to their maximum recovery. In addition, the optimum stirring speed and time for SC were 1400 rpm and 2 min, respectively, while 2000 rpm and 3 min for HIC, respectively. The optimum energy requirements involving stirring speed and time for SC do not match that for reagent dispersion and particle-reagent collision. The best flotation result achieved by HIC is a compromise of the above three aspects. It is suggested that SC, reagent dispersion, and particle-reagent collision should be carried out separately.