化工进展 ›› 2020, Vol. 39 ›› Issue (11): 4734-4741.DOI: 10.16085/j.issn.1000-6613.2020-0790

• 资源与环境化工 • 上一篇    下一篇

富氧气氛下改性生物质焦脱汞的氧化机理

沈昊天1(), 王卉1(), 沈畅2, 吴建飞1   

  1. 1.南京理工大学能源与动力工程学院,江苏 南京 210094
    2.南京理工大学钱学森学院,江苏 南京 210094
  • 出版日期:2020-11-05 发布日期:2020-11-06
  • 通讯作者: 王卉
  • 作者简介:沈昊天(1995—),男,硕士研究生,研究方向为燃煤汞污染物控制。E-mail:haotian1028@outlook.com
  • 基金资助:
    国家自然科学基金(51706104);江苏省自然科学基金(BK20170849);江苏省六大人才高峰项目(XNY-026)

Oxidation mechanism of mercury removal by modified biomass char under oxy-fuel condition

Haotian SHEN1(), Hui WANG1(), Chang SHEN2, Jianfei WU1   

  1. 1.School of Energy and Power Engineering, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China
    2.Tsien Hsue-shen College, Nanjing University of Science and Technology, Nanjing 210094, Jiangsu, China
  • Online:2020-11-05 Published:2020-11-06
  • Contact: Hui WANG

摘要:

富氧燃烧作为新型燃烧方式可以有效减少CO2排放,提高燃烧效率,与传统燃烧方式相比,烟气组分也产生较大的变化。玉米秸秆焦可以作为吸附剂在燃烧后阶段对汞进行脱除。本文采用1% NH4Cl溶液浸渍的玉米秸秆焦为吸附剂,在富氧气氛下探究NO及O2对汞氧化脱除机理。文中指出玉米秸秆焦经浸渍改性处理后,其表面孔隙结构更加丰富,比表面积以及总孔容积增大。同时,改性后表面官能团的数量大大增加,尤其是含氧的官能团,对汞的吸附起着重要作用。富氧气氛下NO与生物质焦表面的O2和含氧基团反应生成具有氧化作用的NO2,与零价汞反应促进汞的去除。NO和O2共存时对零价汞的氧化有更明显的促进作用。O2含量的增加也会促进生物质焦对汞的吸附,这主要是由于O2的强氧化作用导致,与零价汞发生非均相氧化反应生成HgO。此外,含氧官能团化学键的断裂也为汞的氧化提供了氧自由基团。

关键词: 汞, 富氧燃烧, 生物质, 改性, 吸附, 氧化

Abstract:

Corn straw char impregnated with 1% NH4Cl solution was used as adsorbent to explore the mechanism of NO and O2 oxidation on removal of mercury in oxygen enriched atmosphere. Compared with the traditional combustion mode, the composition of oxy-fuel flue gas also changed greatly. In this experiment, corn straw char impregnated with 1% NH4Cl solution was used as adsorbent to explore the mechanism of oxidation with NO and O2 on removal of mercury in oxy-fuel combustion atmosphere. The results showed that the surface pore structure of corn straw char was enriched after impregnation, with more mesoporous structure and increased total pore volume. At the same time, the results of Fourier transform infrared spectrometer showed that the number of functional groups on the surface was greatly increased, especially the oxygen-containing functional groups, which played an important role in the adsorption of mercury. NO could react with O2 and oxygen-containing groups on the surface of biomass char to form NO2 with oxidation effect, which reacted with zero valent mercury to promote the removal of mercury. The co-existence of NO and O2 had more obvious effect on the oxidation of zero valent mercury. The increase of O2 content could also promote the adsorption of mercury on biomass char, which was mainly due to the strong oxidation of O2, i.e., O2 made heterogeneous oxidation with zero valent mercury. In addition, the breaking of chemical bond of oxygen-containing functional group could also provide support for the oxidation of mercury.

Key words: mercury, oxy-fuel, biomass, modification, adsorption, oxidation

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