Yan Wang,Kangqi Cao,Wenlong Sun,Xiangxi Lin,Jianwei Wang,Jessica Villarreal,Longzhi Li
Microwave catalytic pyrolysis of lignin is one of emerging technologies for efficiently converting lignin into fuels and chemicals. Molecular sieves (HZSM-5) are widely used as carriers to load metallic components for biomass pyrolysis but often encounter challenges such as high diffusion resistance and insufficient acidity of acidic sites. Traditionally, HZSM-5 is directly modified to enhance the activity of the acidic sites, but this modification is ineffective in improving the metallic components’ activity. Instead, we made nitrogen doping on Fe and then supported on HZSM-5 to construct Fe-N 25 /HZSM-5 catalysts for microwave catalytic pyrolysis of lignin. The N-doped Fe has the effect of “killing two birds with one stone” on enhancing the catalytic activity. The characterization results indicated that N replaced C of the graphitic carbon network to form carbon nitride structure, and further combined with Fe to generate Fe-N bonds, improving the electronegativity of the metallic component. Besides, the loading of N-doped Fe increased the acidity of the catalyst. The utilization of 1.00Fe-N 25 /HZSM-5 obtained the greatest bio-gas yield (35.2 wt%), a hydrogen yield of 27.8 mL/min, bio-oil yield (36.4 wt%) and phenol selectivity of 46.2 %. The likely pathway of microwave catalytic pyrolysis on Fe-N 25 /HZSM-5 was proposed through DFT calculation, using guaiacol as a model compound. The results suggested that N-doped Fe on HZSM-5 8 T tended to break the side-chain methoxy during pyrolysis of guaiacol, with energy barrier of 0.14 eV. This paper provides a promising strategy for modification of microwave pyrolysis catalysts.
Developing cost-effective and efficient non-precious metal oxygen reduction catalysts (ORRs) is crucial for advancing renewable energy technologies. This study reports the synthesis and characterization of a novel non-precious metal catalyst, N–C–Fe-600, synthesized via a simple two-step method. Pyrolysis of NH 2 –MIL-88(Fe) under an inert atmosphere, followed by acidic treatment, yielded a porous N–C–Fe-600 material featuring a high surface area and a substantial concentration of active Fe–N x sites. Electrochemical characterization revealed that N–C–Fe-600 exhibits ORR activity comparable to commercial Pt/C catalysts, along with significantly enhanced stability and methanol tolerance. The catalyst demonstrates a near-ideal four-electron transfer pathway, suggesting its potential as a viable alternative to platinum-based catalysts in fuel cells.
The widespread use of tetracycline (TC) is a non-negligible cause of environmental pollution , such as antibiotic resistance genes (ARGs). Economical, green and efficient treatment methods are urgently needed. In this study, the magnetic N-doped iron sludge based biochar (N-BCFe) was prepared by a one-step pyrolysis method using the iron-containing sludge from groundwater treatment plants, sycamore leaves and urea as raw materials to active persulfate (PS) for TC degradation . The results show that under the optimal experimental conditions, the removal rate of 10 mg/L TC in the N-BCFe/PS system could reach 86.56% (120 min), accompanied by a 59.9% reduction in total organic carbon (TOC), and still 63.34% of TC was removed in the third recycle experiment. Combined with EPR, free radical quenching experiments and XPS spectra, it is confirmed that there are free radicals ( S O 4 · − , ·OH) and non-radical ( 1 O 2 ) pathways in N-BCFe/PS system. And the former is related to Fe doping, while the latter is attributed to N doping (nitrogen-containing functional groups). Seventeen TC intermediates were identified by LC-MS technology, and three TC degradation pathways were established accordingly. Generally, this study illustrates the considerable catalytic potential of N-BCFe and provides valuable insights into the synthesis of catalysts prepared from iron-containing sludge as feedstock.
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