A two-step method for the integrated removal of HCl, SO2 and NO at low temperature using viscose-based activated carbon fibers modified by nitric acid. (1st March 2019)

• Record Type: Journal Article
• Authors: Wang, Zean; Jin, Hu; Wang, Kun; Xie, Yihao; Ning, Jian; Tu, Yaojie; Chen, Yingming; Liu, Hao; Zeng, Hancai
• Is Part Of: Fuel. Volume 239(2019)
• Page Start: 272
• Page End: 281
• Publication Date: 2019-03-01
• Subjects: Activated carbon fibers -- Integrated removal -- Hydrogen chloride -- Sulfur oxides -- Nitrogen oxides; Fuel -- Periodicals; Coal -- Periodicals; Coal; Fuel; Periodicals; 662.6
• DOI: 10.1016/j.fuel.2018.11.002
• Languages: English
• ISSNs: 0016-2361

Abstract

Graphical abstract: Highlights: The two-step process significantly enhanced the removal of HCl, SO2 and NO by the activated carbon fibers. HCl strongly inhibited the adsorptions of SO2 and NO while SO2 hindered the physisorption of HCl. Surface nitro/nitroso groups can promote the chemisorption of HCl. HNO3 treatment can favor the integrated removal of HCl, SO2 and NO. Abstract: Activated carbon fibers (ACFs) have been widely used as cost-effective integrated processes for the removal of nitrogen oxides, sulfur oxides and hydrogen chloride (HCl), while the competitive adsorption behaviors and the detailed interaction mechanisms have not been comprehensively investigated. In the current work, the adsorption capacities with one-step process and two-step method were compared, and the effects of HNO3 modification and ambient O2 concentration were simultaneously studied. Furthermore, the relative ratios of surface nitrogen groups, sulfur and chlorine compounds, as well as the soluble species on the ACFs surface, were respectively characterized by X-ray photoelectron spectroscopy and ion chromatography techniques. The results indicated that HCl, SO2 and NO were not able to be effectively removed with only one reactor due to the strong competitive adsorption behaviors, while the adsorption capacities of HCl, SO2 and NO were significantly improved by 30%, 280%, 230% in the two-stage reactors with HNO3 modification. Further investigation indicated interactions between HCl, SO2 and NO in the two-stage reactors are very complicated. The primary reactor can remove HCl and facilitate the catalytic removal of SO2 /NO in the secondary reactor since HCl can severely inhibit the adsorptions of SO2 and NO, yet HCl adsorption can be suppressed by SO2 . Simultaneously, nitro/nitroso groups derived of HNO3 treatment and NO oxidation can promote the chemisorption of HCl.