APPLIED CATALYSIS A-GENERAL
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2016
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IF 4.012
Peng Sun,Rui-tang Guo,Shu-ming Liu,Shu-xian Wang,Wei-guo Pan,Ming-yuan Li
A series of MnEuOx catalysts were prepared by the co-precipitation method and used for selective catalytic reduction of NOx with NH 3 . It was found that the modification of MnOx catalyst by Eu with a Eu/Mn molar ratio of 0.1 could greatly enhance its SCR activity and broaden its operating temperature window, accompanied by good resistance to SO 2 and H 2 O. From the characterization results of N 2 adsorption, XRD, XPS, H 2 -TPR, it could be concluded that the larger surface area resulted from the inhibited crystallization of MnOx, the enrichment of surface Mn 4+ and chemisorbed oxygen, and the higher reducibility all made a contribution to the high SCR activity of MnEuOx-0.1 catalyst. Furthermore, the results of in situ DRIFTS study revealed the NH 3 -SCR reactions over MnOx and MnEuOx-0.1 were mainly controlled by L-H mechanism (<150 °C) and E-R mechanism (>150 °C) respectively, and the contribution of E–R mechanism became more important with increasing reaction temperature. The enhanced NO oxidation and NH 3 adsorption should be mainly contribute to the distinguished SCR performance of MnEuOx catalyst in the lower temperature range (<150 °C) and higher temperature range (>150 °C) respectively.
研究领域:
催化化学
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环境科学
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DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 10
·4335-4345
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IF 2.7
Jiali Zhang,Zhen Yan,Yanke Yu,Yanpeng Li
CuO/TiO2 catalysts with varying Sb doping ratios were synthesized and applied in the NH3-SCR process. The results of activity tests revealed that the addition of Sb effectively enhanced the performance of low-temperature SCR. Particularly, the CuSbTiOx-0.2 catalyst exhibited the highest activity, achieving over 91% conversion at 250 °C, along with the highest N2 selectivity and exceptional resistance to SO2. Comprehensive characterization analyses demonstrated that CuSbTiOx-0.2 possessed a significantly large specific surface area, the strongest surface acidity, and superior redox performance among the catalysts studied. In situ DRIFTS experiments provided further insights, indicating that Sb modification generated more active species, thereby enhancing the reactivity of ad-NH3 and ad-NOx species. The SCR reaction mechanism for CuSbTiOx-0.2 predominantly followed the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanisms. These findings have the potential to advance the development of novel and effective non-vanadium SCR catalysts.
研究领域:
环境科学
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催化材料
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产品关联
DOI
高影响因子
INORGANIC CHEMISTRY
·
2024
·
IF 4.3
Chaoqun Bian,Xiaohui Luo,Xiao Chen,Rongrong Liu,Jingqiu Li,Gaoyuan Zhu,Hao Xu,Shichao Han,Jie Zhu,Longfeng Zhu
Cu-SSZ-39 zeolite with 8-membered rings is regarded as a very promising catalyst in the NH3-SCR reaction, but its hydrothermal stability still remains to be improved. One of the solutions to promote hydrothermal stability is the insertion of rare earth elements in the product. Nevertheless, normal ion exchange of rare earth elements limits their contents in the zeolite product due to their large hydrated ionic radius and alkaline environment under hydrothermal conditions. Herein, we for the first time present a new method for the one-pot synthesis of Ce-SSZ-39 zeolite under solvent-free conditions. The key to success is the use of Ce-FAU zeolite as a precursor. The obtained product shows good crystallinity, sheet-like morphology, large BET surface area, and 4-coordinated Al species. Detailed investigations illustrate that Ce species in the Cu/Ce-SSZ-39 zeolite micropore can prevent the dealumination and thus formation of CuAlOx species during hydrothermal aging at 850 °C for 16 h, giving the excellent hydrothermal stability and thus showing the excellent catalytic performance in the NH3-SCR reaction. One-pot synthesis of Ce-SSZ-39 zeolite with excellent catalytic performance might open a new door for developing very efficient selective catalytic reduction (SCR) catalysts in near future.
研究领域:
催化材料
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环境化学
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产品关联
DOI
PubMed
高影响因子
FUEL
·
2023
·
IF 7.4
Guoquan Liu,He Zhang,Pengfei Wang,Yi Li,Xueyue Mi,Sihui Zhan
Reducing the poisoning effect of alkaline earth metals over catalysts in industrial fields presents a great challenge to selective catalytic reduction (SCR) of NO x with ammonia. Herein, we successfully introduce sulfates to the surface of supported manganese-based oxides (Nb/MnO 2 -S) for trapping calcium species, and Nb/MnO 2 -S catalyst with superior low-temperature performance and calcium-resistant property still exhibits excellent de-NO x activity in a wide operating temperature window (175–350 °C, over 80 % NO x conversion with a gas hourly space velocity of 60,000 h −1 ) after calcium poisoning. In this case, the addition of sulfates increased the quantity of chemisorbed oxygen on Nb/MnO 2 -S, thus accelerating the redox cycle in NH 3 -SCR reaction. Significantly, compared with calcium-poisoned Nb/MnO 2 , relevant spectroscopy analysis and theoretical calculations further reveal that sulfates species prefer to interact with calcium and release the Nb active sites, which maintains the efficient NH 3 adsorption and preserves a large amount of Brønsted acid sites over calcium-poisoned Nb/MnO 2 -S, thus promoting calcium-resistant performance. This work will provide a general strategy to develop calcium-resistant SCR catalysts with low-temperature activity for industrial applications.
研究领域:
催化化学
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环境科学
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产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Kaiting Chen,Xinyu Han,Qian Wang,Kaijie Liu,Xiangguang Yang,Yibo Zhang
The selective catalytic reduction of NO by CO (CO-SCR) presents an economical and promising approach to mitigate emissions of NO x and CO from motor vehicles. A bimetallic Rh-Mn supported catalyst Rh-Mn/CoAlO was synthesized through the reduction of citric acid and ethylene glycol, and subsequently employed in the CO-SCR reaction. Tests assessing its catalytic performance revealed that the Rh-Mn/CoAlO catalyst displayed superior CO-SCR activity, maintaining high efficiency (≥90 % at 230 °C) and stability while simultaneously reducing the usage of noble metals. Various characterization techniques, including H 2 -TPR, NO-TPD, CO-pulse, and XPS, indicated that the Rh-Mn/CoAlO catalyst possessed enhanced dispersion of noble metals. This increased dispersion ensured optimal contact between Rh and Mn, as well as the support, fostering a synergistic interaction that facilitated electron transfer. Consequently, the catalyst’s adsorption and activation capabilities for NO were significantly improved. In situ DRIFTs studies further elucidated that the catalyst primarily followed the E-R mechanism, wherein NO is adsorbed onto the catalyst surface, and subsequently, the N and O atoms generated from pyrolysis react with CO in the gas phase. The findings of this study are anticipated to offer an effective strategy for designing catalysts with exceptional low-temperature activity and high dispersibility for the reduction of NO using CO.
研究领域:
环境科学
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催化化学
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DOI
高影响因子
WATER ENVIRONMENT RESEARCH
·
2016
·Vol. 88
·期 12
·2219-2227
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IF 0.659
Xuelong Sha,Wei Ma,Fanqing Meng,Ren Wang,Tian Fuping,Linsen Wei
In this study, we explored an effective and low-cost catalyst and its adsorption capacity and catalytic capacity for Methyl Orange Fenton oxidation degradation were investigated. The catalyst was directly prepared by reuse of magnetic iron oxide (Fe 3 O 4 ) after saturated adsorption of vanadium (V) from waste SCR (Selective Catalytic Reduction) catalyst. The obtained catalyst was characterized by FTIR, XPS and the results showed that vanadium (V) adsorption process of Fe 3 O 4 nanoparticles was non-redox reaction. The effects of pH, adsorption kinetics and equilibrium isotherms of adsorption were assessed. Adsorption of vanadium (V) ions by Fe 3 O 4 nanoparticles could be well described by the Sips isotherm model which controlled by the mixed surface reaction and diffusion (MSRDC) adsorption kinetic model. The results show that vanadium (V) was mainly adsorbed on external surface of the Fe 3 O 4 nanoparticles. The separation-recovering tungsten (VI) and vanadium (V) from waste SCR catalyst alkaline solution through pH adjustment was also investigated in this study. The results obtained from the experiments indicated that tungsten (VI) was selectively adsorbed from vanadium (V)/tungsten (VI) mixed solution in certain acidic condition by Fe 3 O 4 nanoparticle to realize their recovery. Tungsten (V) with some impurity can be obtained by releasing from adsorbent, which can be confirmed by ICP-AES. The Methyl Orange degradation catalytic performance illustrated that the catalyst could improve Fenton reaction effectively at pH = 3.0 compare to Fe 3 O 4 nanoparticles alone. Therefore, Fe 3 O 4 nanoparticle adsorbed vanadium (V) has a potential to be employed as a heterogeneous Fenton-like catalyst in the present contribution, and its catalytic activity was mainly evaluated in terms of the decoloration efficiency of Methyl Orange.
研究领域:
环境科学
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催化材料
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废水处理
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
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IF 16.744
Rui Li,Xiangqiong Jiang,Jiecheng Lin,Zhiping Zhang,Qintong Huang,Guangying Fu,Yujun Zhu,Jiuxing Jiang
SSZ-16 zeolite with AFX topology was synthesized by hydrothermal method using 1,4-diazabicyclo[2.2.2]-octane-C4-diquat dibromide as organic structure directing agent. Cu x -SSZ-16 catalysts were prepared by exchanging SSZ-16 zeolite with Cu and applied for selective catalytic reduction (SCR) of NO x with ammonia. Among these catalysts, Cu 2.2 -SSZ-16 performs the best SCR denitration (deNO x ) performance that above 90% NO x conversion can be achieved at 175–600 °C. Especially, the influences of the hydrothermal aging at various temperatures (650, 750 and 850 °C) on active species and AFX framework of the Cu 2.2 -SSZ-16 catalyst are investigated in detail by various characterization methods including XRD, SEM , H 2 -TPR, NMR, UV–vis-DRS, EPR, NH 3 -TPD and in situ DRIFTS . Cu 2.2 -SSZ-16 still shows good NH 3 -SCR activity after hydrothermal aging at 650 and 750 °C due to more Cu 2+ -2Z species in the sample. Still, obvious deactivation can be observed after hydrothermal aging at 850 °C because of the collapse of AFX skeleton and the weak interaction between active Cu species and the skeleton. Nevertheless, Cu 2.2 -SSZ-16 is a competitive candidate for NH 3 -SCR deNO x reaction in practical applications.
研究领域:
催化化学
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环境科学
✓ 已验证
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
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2024
·
IF 0
You Mengyun,Wu Shufeng,Feng Xiaotong,Zhao Yong,Wang Yubin,Zhang Zhang
The enhancement effect of Ce modification on V 2 O 5 -WO 3 /TiO 2 catalysts at low temperatures was investigated for the selective catalytic reduction (SCR) of NO x with NH 3 (NH 3 -SCR). By adding 9% CeO 2 to 0.5%V 2 O 5 -3%WO 3 /TiO 2 catalyst, the low-temperature denitrification performance of Ce 9 V 0.5 W 3 Ti catalyst after Ce modification was significantly improved, achieving a NO conversion above 90% within a broad temperature range of 200–350℃, with catalytic activity comparable to that of 3% V 2 O 5 -3% WO 3 /TiO 2 . The catalysts were characterized by XPS, H 2 -TPR, NH 3 , and NO-TPD. The results indicated that the Ce additive could enhance the adsorption of NO x on Ce 9 V 0.5 W 3 Ti catalyst due to the synergetic interaction among the Ce and V, W species. The interaction between V and Ce also promoted the formation of V 5+ and Ce 3+ on the surface of the catalyst, which was conducive to enhancing the adsorption and oxidation capacity of the catalyst for NO. Additionally, the introduction of Ce led to a substantial deposition of nitrate species on the surface of the catalyst, especially the increase of nitrite species, which was beneficial to the NH 3 -SCR reaction process, resulting in a significant enhancement of the catalyst’s low-temperature catalytic activity.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
CHINESE JOURNAL OF CATALYSIS
·
2018
·
IF 3.525
Lei Chen,Ding Weng,Jiadao Wang,Duan Weng,Li Cao
The CeO 2 -TiO 2 (CeTi) and CeO 2 /WO 3 -TiO 2 (CeWTi) catalysts were prepared by a sol-gel precipitation method and their NH 3 -NO/NO 2 selective catalytic reduction (SCR) performance was studied. N 2 O formation and effect of oxygen concentration on SCR performance over CeWTi catalyst were also investigated while varying the NO 2 /NO x ratio. Results indicate that fast SCR behavior of CeWTi catalyst has the best NH 3 -NO/NO 2 SCR performance due to the catalyst reoxidation rate by NO 2 higher than by O 2 . Compared with CeTi catalyst, CeWTi catalyst exhibits higher de-NO x performance under NH 3 -NO/NO 2 SCR conditions. As the CeTi and CeWTi catalysts exhibit similar redox property, addition of WO 3 provides more acid sites which accelerate the reaction between NH 4 NO 3 and NO to get a superior low-temperature activity. Amount of N 2 O formation shows a peak at 250 °C mainly derived from NH 4 NO 3 decomposition.
研究领域:
催化劑科學
·
環境工程
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产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2021
·Vol. 152
·期 8
·2270-2279
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IF 3.186
Bie Xuan,Jiao Kunling,Gong Chunqin,Qu Baozhong,Liu Daokuan,Ma Shuangchen
To develop highly efficient NH 3 -SCR catalysts with a wide temperature range, catalysts based on MnAlO x and Cerium elements loading with various mixing ratios were prepared for selective catalytic reduction of NO by NH 3 . The special role of cerium was demonstrated by the surface structure characteristics and unique catalytic performance, involving the surface-active sites and compositions analysis. Interestingly, the strengthening of Mn 1.2 Al 0.8 Ce a O x on both acid sites, especially medium acids and strong acids, were clearly manifested. Meanwhile, the strong interaction between MnAlOx and CeO 2 enabled favorable electron transfers from MnOx to CeO 2 while generating more oxygen vacancies and active oxygen species, consequently accelerating the redox cycle. The results illustrate that the NOx conversion and the selectivity of N 2 can be improved with more medium acids tuned by appropriate Ce adding. However, an opposite effect will appear by excessive addition. In addition, the reaction mechanisms at different acid sites are revealed. Our findings, therefore, provide a strategy for the rational design of moderate-temperature NH 3 -SCR catalysts through adding-induced component engineering of composite materials. Graphic Abstract Mn 1.2 Al 0.8 Ce a O x Catalysts with different surface features were fabricated by an environment-friendly method. The strong interaction between MnAlOx and CeO 2 was systematically illustrated. Meanwhile, the importance of medium acids was convincingly revealed. And the reaction mechanisms at different acid sites were demonstrated. These provide a strategy for the rational design of moderate-temperature NH 3 -SCR catalysts through adding-induced component engineering of composite materials.
研究领域:
催化化学
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环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2020
·Vol. 10
·期 23
·8086-8093
·
IF 5.721
Haoxi Jiang,Debin Kong,Ying Niu,Sheng Wang
MnO2–CoOX catalysts with different Mn/Co ratios were prepared using polyvinyl pyrrolidone (PVP) as an assistant to control the morphology and exposed crystal faces of composite oxides. The physicochemical properties of the catalysts were systematically characterized and the catalytic activity of NH3-SCR and resistance to SO2/H2O were investigated. It was found that the NO conversion over Mn–Co-0.2-PVP was apparently higher compared with that over Mn–Co-X-PVP (X = 0.9, 0.8, 0.6, and 0.4). This can be interpreted in terms of exposed crystal surface (110) and enhanced adsorption of NH3/NO, and better redox performance resulting from higher Co3+/Co2+ ratio. Furthermore, different PVP and HAc additives have different H2O and SO2 resistance. Mn–Co-0.2-PVP showed good resistance to H2O and SO2 poisoning owing to having more low-temperature (∼200 °C) NO adsorption sites, which are beneficial to promote the de-NOX reaction and less affected by SO2.
研究领域:
环境科学
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2019
·
IF 8.355
Xiaoqiang Wang,Yue Liu,Zhongbiao Wu
In this paper, the Cu-Ce based catalyst using NbOPO 4 (Nb-P) as support was firstly employed for selective catalytic reduction (SCR) of NO by NH 3 . The experimental results had illustrated that such catalyst exhibited well SCR activity and N 2 selectivity within a wide temperature range of 200–450 °C. These superior performances could be mainly attributed to its improved textural properties and strong acidity derived from NbOPO 4 support. More importantly, the sulfur tolerance of the NbOPO 4 supported Cu-Ce sample was found greatly improved compared to TiO 2 and Ti-Nb supported samples, where above 80% SCR activity of Cu-Ce/Nb-P sample was obtained at 250 °C after 10 h reaction running in the presence of 100 ppm SO 2 . This fact was the result of the enhanced acidity and the strong interactions between Cu-Ce oxides and NbOPO 4 support, which could prevent the surface oxygen species from sulfation by SO 2 . As such, these oxygen species strongly associated with NbOPO 4 support still could activate adsorbed NH 3 to fulfill the SCR reaction cycle, leading to its better sulfur resistance. The work would provide some enlightenments to the development of NH 3 -SCR catalysts with high sulfur resistance at medium-high temperature.
研究领域:
催化化学
·
环境科学
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）