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Duan R, Li Z, Fu Y, Shan Y, Yu Y, He G, He H. Combined Experimental and Density Functional Theory Study on the Mechanism of the Selective Catalytic Reduction of NO with NH 3 over Metal-Free Carbon-Based Catalysts. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2024; 58:5598-5605. [PMID: 38466913 DOI: 10.1021/acs.est.4c00584] [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: 03/13/2024]
Abstract
Metal-free carbon-based catalysts are attracting much attention in the low-temperature selective catalytic reduction of NOx with NH3 (NH3-SCR). However, the mechanism of the NH3-SCR reaction on carbon-based catalysts is still controversial, which severely limits the development of carbon-based SCR catalysts. Herein, we successfully reconstructed carbon-based catalysts through oxidation treatment with nitric acid, thereby enhancing their low-temperature activity in NH3-SCR. Combining experimental results and density functional theory (DFT) calculations, we proposed a previously unreported NH3-SCR reaction mechanism over carbon-based catalysts. We demonstrated that C-OH and C-O-C groups not only effectively activate NH3 but also remarkedly promote the decomposition of intermediate NH2NO. This study enhances the understanding of the NH3-SCR mechanism on carbon-based catalysts and paves the way to develop low-temperature metal-free SCR catalysts.
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Affiliation(s)
- Rucheng Duan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhuocan Li
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu Fu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yulong Shan
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
| | - Yunbo Yu
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
| | - Guangzhi He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Hong He
- State Key Joint Laboratory of Environment Simulation and Pollution Control, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China
- University of Chinese Academy of Sciences, Beijing 100049, China
- Center for Excellence in Regional Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
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Li C, Hu Z, Jiang G, Zhang Y, Wu Z. 3D Carbon Microspheres with a Maze-Like Structure and Large Mesopore Tunnels Built From Rapid Aerosol-Confined Coherent Salt/Surfactant Templating. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2024; 20:e2305316. [PMID: 37661568 DOI: 10.1002/smll.202305316] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2023] [Revised: 08/21/2023] [Indexed: 09/05/2023]
Abstract
Hierarchically porous carbons with tailor-made properties are essential for applications wherein rich active sites and fast mass transfer are required. Herein, a rapid aerosol-confined salt/surfactant templating approach is proposed for synthesizing hierarchically porous carbon microspheres (HPCMs) with a maze-like structure and large mesopore tunnels for high-performance tri-phase catalytic ozonation. The confined assembly in drying microdroplets is crucial for coherent salt (NaCl) and surfactant (F127) dual templating without macroscopic phase separation. The HPCMs possess tunable sizes, a maze-like structure with highly open macropores (0.3-30 µm) templated from NaCl crystal arrays, large intrawall mesopore tunnels (10-45 nm) templated from F127, and rich micropores (surface area >1000 m2 g-1 ) and oxygen heteroatoms originated from NaCl-confined carbonization of phenolic resin. The structure formation mechanism of the HPCMs and several influencing factors on properties are elaborated. The HPCMs exhibit superior performance in gas-liquid-solid tri-phase catalytic ozonation for oxalate degradation, owing to their hierarchical pore structure for fast mass transfer and rich defects and oxygen-containing groups (especially carbonyl) for efficient O3 activation. The reactive oxygen species responsible for oxalate degradation and the influences of several structure parameters on performance are discussed. This work may provide a platform for producing hierarchically porous materials for various applications.
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Affiliation(s)
- Cancan Li
- Particle Engineering Laboratory, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, Jiangsu, 2151213, P. R. China
| | - Zeyu Hu
- Particle Engineering Laboratory, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, Jiangsu, 2151213, P. R. China
| | - Guanyun Jiang
- Particle Engineering Laboratory, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, Jiangsu, 2151213, P. R. China
| | - Yali Zhang
- Particle Engineering Laboratory, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, Jiangsu, 2151213, P. R. China
| | - Zhangxiong Wu
- Particle Engineering Laboratory, School of Chemical and Environmental Engineering, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou City, Jiangsu, 2151213, P. R. 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: 2] [Impact Index Per Article: 2.0] [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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Wang L, Liu M, Ren S, Li X, Chen Z, Wang M, Chen T, Yang J. Recent advance for NO removal with carbonaceous material for low-temperature NH3-SCR reaction. Catal Today 2023. [DOI: 10.1016/j.cattod.2023.114053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/21/2023]
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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: 3.0] [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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Wang Y, Shi T, Fan QY, Liu Y, Zhang A, Li Z, Hao Y, Chen L, Liu F, Gu X, Zeng S. Discovering Surface Structure and the Mechanism of Graphene Oxide-Triggered CeO 2–WO 3/TiO 2 Catalysts for NO Abatement with NH 3. ACS Catal 2022. [DOI: 10.1021/acscatal.2c01364] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Yan Wang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
- State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization, Baotou Research Institute of Rare Earths, Baotou 014030, China
| | - Tong Shi
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Qi-Yuan Fan
- State Key Laboratory of Physical Chemistry of Solid Surface, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yang Liu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Aiai Zhang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Zhaoqiang Li
- State Key Laboratory of Baiyunobo Rare Earth Resource Researches and Comprehensive Utilization, Baotou Research Institute of Rare Earths, Baotou 014030, China
| | - Yanheng Hao
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Lin Chen
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Fenrong Liu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Xiaojun Gu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
| | - Shanghong Zeng
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot 010021, China
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