Electric Power Technology and Environmental Protection

【目的】汞作为具有生物累积性及长距离迁移能力的有毒重金属，燃煤锅炉是最大人为汞排放污染源。在碳减排背景下，利用零碳生物质资源开发高效廉价脱汞吸附剂，成为控制燃煤烟气汞污染的关键研究方向。【方法】本文以废弃木屑为原料，采用水热碳化法制备了FeCl_(3)改性水热炭(Fe_(1.3)-HC)，在固定床实验装置上考察了其脱汞性能，结合量子化学计算，揭示了FeCl_(3) 改性水热炭脱除Hg⁰的高效吸附机理。【结果】研究表明，制备得到的Fe_(1.3)-HC在50~250 ℃、不同入口汞浓度(15.4~44.9 μg/m³)及含SO₂(0~2400 mg/m³)的复杂烟气中均表现出优异的脱汞性能，平均脱汞效率达98%以上；O₂的存在显著增强Fe_(1.3)-HC的吸附性能，SO₂通过氧化生成HgSO₄进一步强化汞固定；量子化学计算表明，α-Fe₂O₃( 0 0 1)晶面的Fe-top位点为Hg⁰化学吸附优势位点，吸附能为-53.21kJ/mol，其Hg-O键短(2.760 Å)且电荷转移显著(0.31 e)，结合投影态密度分析证实Hg⁰与表面Fe、O原子轨道杂化形成稳定化学键，从电子尺度验证了Hg⁰与Fe、O原子的强相互作用机制。【结论】本研究采用水热法制备FeCl_(3)改性水热炭，获得了最佳制备参数并揭示了其内在的脱汞机理，为开发抗硫、宽温域适应性强的脱汞吸附剂提供了实验与理论依据。

[Objective] Mercury, a toxic heavy metal with bioaccumulative and long-range transport capabilities, is predominantly emitted from coal-fired boilers. Under carbon neutrality initiatives, developing cost-effective mercury sorbents using zero-carbon biomass resources hasbecome critical for controlling Hg~0  emissions from coal flue gas.[Methods]Herein, FeCl_(3)-modified hydrochar (Fe_(1.3)-HC) was synthesized from wood waste via hydrothermal carbonization. Its Hg~0 removal performance was systematically evaluated in a fixed-bed experimental system under varying temperatures (50-250 ℃), inlet Hg0 concentrations (15.4-44.9 μg/m³), and SO₂levels (0-2 400 mg/m³). Quantum chemical calculations were conducted to elucidate the adsorption mechanism.[Results]Fe_(1.3)-HC exhibited exceptional Hg~0 removal efficiency (>98%) across tested conditions. O_(2) enhanced Hg~0  oxidation, while SO_(2) promoted Hg fixation via HgSO_(4) formation. DFT calculations identified Fe-top sites on α-Fe_(2)O_(3) (0 0 1) as preferential sites for Hg~0  chemisorption, with strong adsorption energy (-53.21 kJ/mol), short Hg-O bond length (2.760 Å), and significant charge transfer (0.31e). PDOS analysis confirmed orbital hybridization between Hg~0 and Fe/O atoms, forming stable chemical bonds，The strong interaction mechanism of Hg~0 with Fe and O atoms is verified from the electronic scale.[Conclusion]This work optimized FeCl_(3)-modified hydrochar synthesis parameters and deciphered its Hg~0 removal mechanism, providing experimental and theoretical foundations for developing sulfur-resistant, wide-temperature-adaptable sorbents for industrial mercury control.