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Gao C, Long J, Yue Y, Li B, Huang Y, Wang Y, Zhang J, Zhang L, Qian G. Degradation and regeneration inhibition of PCDD/Fs in incineration fly ash by low-temperature thermal technology. JOURNAL OF HAZARDOUS MATERIALS 2024; 477:135315. [PMID: 39096638 DOI: 10.1016/j.jhazmat.2024.135315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2024] [Revised: 07/17/2024] [Accepted: 07/23/2024] [Indexed: 08/05/2024]
Abstract
Low-temperature thermal degradation of PCDD/Fs for incineration fly ash (IFA), as a novel and emerging technology approach, offers promising features of high degradation efficiency and low energy consumption, presenting enormous potential for application in IFA resource utilization processes. This review summarizes the concentrations, congener distributions, and heterogeneity characteristics of PCDD/Fs in IFA from municipal, medical, and hazardous waste incineration. A comparative analysis of five PCDD/Fs degradation technologies is conducted regarding their characteristics, industrial potential, and applicability. From the perspective of low-temperature degradation mechanisms, pathways to enhance PCDD/Fs degradation efficiency and inhibit their regeneration reactions are discussed in detail. Finally, the challenges to achieve low-temperature degradation of PCDD/Fs for IFA with high-efficiency are prospected. This review seeks to explore new opportunities for the detoxification and resource utilization of IFA by implementing more efficient and viable low-temperature degradation technologies.
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Affiliation(s)
- Chenqi Gao
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Jisheng Long
- Shanghai SUS Environment Co., LTD., Shanghai 201703, China
| | - Yang Yue
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Bin Li
- Shanghai SUS Environment Co., LTD., Shanghai 201703, China
| | - Yiru Huang
- Shanghai SUS Environment Co., LTD., Shanghai 201703, China
| | - Yao Wang
- Department of Environment and Architecture, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Jia Zhang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China
| | - Lingen Zhang
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
| | - Guangren Qian
- School of Environmental and Chemical Engineering, Shanghai University, Shanghai 200444, China.
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Wang Q, Wu Z, Wang R, Tang M, Lu S, Cai T, Qiu J, Jin J, Peng Y. New mechanistic insight into catalytic decomposition of dioxins over MnO x-CeO 2/TiO 2 catalysts: A combined experimental and density functional theory study. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 921:170911. [PMID: 38354796 DOI: 10.1016/j.scitotenv.2024.170911] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2023] [Revised: 02/02/2024] [Accepted: 02/09/2024] [Indexed: 02/16/2024]
Abstract
Elucidation of the catalytic decomposition mechanism of dioxins is pivotal in developing highly efficient dioxin degradation catalysts. In order to accurately simulate the whole molecular structure of dioxins, two model compounds, o-dichlorobenzene (o-DCB) and furan, were employed to represent the chlorinated benzene ring and oxygenated central ring within a dioxin molecule, respectively. Experiments and Density Functional Theory (DFT) calculations were combined to investigate the adsorption as well as oxidation of o-DCB and furan over MnOx-CeO2/TiO2 catalyst (denoted as MnCe/Ti). The results indicate that competitive adsorption exists between furan and o-DCB. The former exhibits superior adsorption capacity on MnCe/Ti catalyst at 100 °C - 150 °C, for it can adsorb on both surface metal atom and surface oxygen vacancies (Ov) via its O-terminal; while the latter adsorbs primarily by anchoring its Cl atom to surface Ov. Regarding oxidation, furan can be completely oxidized at 150 °C - 300 °C with a high CO2 selectivity (above 80 %). However, o-DCB cannot be totally oxidized and the resulting intermediates cause the deactivation of catalyst. Interestingly, the pre-adsorption of furan on catalyst surface can facilitate the catalytic oxidation of o-DCB below 200 °C, possibly because the dissociated adsorption of furan may form additional reactive oxygen species on catalyst surface. Therefore, this work provides new insights into the catalytic decomposition mechanism of dioxins as well as the optimization strategies for developing dioxin-degradation catalysts with high efficiency at low temperature.
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Affiliation(s)
- Qiulin Wang
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Zhihao Wu
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Rui Wang
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Minghui Tang
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
| | - Shengyong Lu
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China; Research Institute of Zhejiang University-Taizhou, Taizhou 318012, Zhejiang, China.
| | - Tianyi Cai
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Juan Qiu
- Research Institute of Zhejiang University-Taizhou, Taizhou 318012, Zhejiang, China
| | - Jing Jin
- School of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093, China
| | - Yaqi Peng
- State Key Laboratory of Clean Energy Utilization, Institute for Thermal Power Engineering, Zhejiang University, Hangzhou 310027, China
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Zhu X, Yuan J, Peng Y, Chen J, Yuan X, Li J. In Situ S-Doping Engineering for Highly Efficient NH 3-SCR over Metal-Free Carbon Catalysts: A Novel Synergetic Promotional Mechanism. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:371-380. [PMID: 38146194 DOI: 10.1021/acs.est.3c07628] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2023]
Abstract
Cyclic desulfurization-regeneration-denitrification based on metal-free carbon materials is one of the most promising ways to remove NOx and SO2 simultaneously. However, the impact of S-doping induced by the cyclic desulfurization and regeneration (C-S-R) process on the selective catalytic reduction (SCR) is not well understood. Herein, it is demonstrated that the C-S-R process at 500 °C induces in situ S-doping with a significant accumulation of C-S-C structures. NOx conversion was dramatically enhanced from 18.95% of the original sample to 84.55% of the S-doped sample. Density functional theory calculations revealed that the C-S-C structure significantly regulates the electronic structure of the C atom adjacent to the ketonic carbonyl group, thereby significantly altering the NH3 adsorption configuration with superior adsorption capacity. Moreover, S-doping induces an extra electron transfer between the N atom of the NH3 molecule and the C atom of the carbon plane, thereby promoting the activation of NH3 over the ketonic carbonyl group with a reduced energy barrier. This study elucidates a synergetic promotional mechanism between the ketonic carbonyl group and the C-S-C structure for SCR, offering a novel design strategy for high-performance heteroatom-doped carbon catalysts in industrial applications.
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Affiliation(s)
- Xiao Zhu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Jin Yuan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
- College of Resources and Environmental Engineering, Guizhou University, Guiyang, Guizhou 550025, P. R. China
| | - Yue Peng
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Jianjun Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Xing Yuan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Junhua Li
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
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Yuan J, Chen J, Wang Z, Yin R, Zhu X, Yang K, Peng Y, Li J. Identification of Active Sites over Metal-Free Carbon Catalysts for Flue Gas Desulfurization. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:2575-2583. [PMID: 36722821 DOI: 10.1021/acs.est.2c09521] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/18/2023]
Abstract
Carbon-based catalysts have been extensively used for flue gas desulfurization (FGD) and have exerted great importance in controlling SO2 emissions over the past decades. However, many fundamental details about the nature of the active sites and desulfurization mechanism still remain unclear. Here, we reported the experimental and theoretical identifications of active sites in FGD on carbon catalysts. Temperature-programmed decomposition allowed us to modulate the number of oxygen functional groups on carbon catalysts and to establish its correlation with desulfurization activity. Selective passivation further demonstrated that the ketonic carbonyl (C═O) groups are the intrinsic active sites for FGD reaction. Combined with transient response experiments, quasi-in situ X-ray photoelectron spectroscopy, and density functional theory simulations, it was revealed that desulfurization reaction on carbon catalysts mainly proceeded via the Langmuir-Hinshelwood mechanism, during which the nucleophilic ketonic C═O groups served as active sites for chemically absorbing SO2 and their adjacent sp2-hybridized carbon atoms dissociatively activated O2. It also turned out that the formation of H2SO4 is the reaction barrier step. The output of this study should not only advance the understanding of desulfurization at the atomic scale but also provide a general guideline for the rational design of efficient carbon catalysts for FGD.
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Affiliation(s)
- Jin Yuan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Jianjun Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Zhen Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Rongqiang Yin
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Xiao Zhu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Kun Yang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Yue Peng
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
| | - Junhua Li
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing 100084, P. R. China
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Yuan J, Wang Z, Liu J, Li J, Chen J. Potential Risk of NH 3 Slip Arisen from Catalytic Inactive Site in Selective Catalytic Reduction of NO x with Metal-Free Carbon Catalysts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2023; 57:606-614. [PMID: 36524894 DOI: 10.1021/acs.est.2c06289] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Ammonia emissions from industrial processes have rapidly increased in the past years. Recent advances have used carbon-based selective catalytic reduction (SCR) technology combined with a reaction-regeneration process to reduce NOx from sintering flue gas, while NH3 slip is seldom accounted for in this process. This study demonstrates that although the electrophilic carboxyl groups (-COOH) on metal-free carbon catalysts exhibit strong adsorption toward NH3, they do not participate in the SCR reaction. As a result of the competitive adsorption of NH3 in the reaction step, these catalytic inactive carboxyl groups not only prolong the time to the SCR steady state, but also result in the potential risk of NH3 slip. A linear relationship with the equimolar ratio between carboxyl groups and slipped NH3 was established in the regeneration steps. The slip of NH3 could be alleviated by the decomposition of carboxyl groups, and special attention should be paid to the presence of inactive sites with strong NH3 adsorption on industrial-employed carbon catalysts. In addition to advancing the understanding of the NH3-SCR mechanism, this work also provides valuable opportunities for the control of ammonia emissions from industrial processes.
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Affiliation(s)
- Jin Yuan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing100084, P. R. China
| | - Zhen Wang
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing100084, P. R. China
| | - Jun Liu
- College of Chemistry, Taiyuan University of Technology, Taiyuan030024, P. R. China
| | - Junhua Li
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing100084, P. R. China
| | - Jianjun Chen
- State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing100084, P. R. China
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