JOURNAL OF RARE EARTHS
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2020
·
IF 3.104
Di Deng,Shujun Deng,Dandan He,Zhiheng Wang,Zhipeng Chen,Yi Ji,Guoping Yan,Guangjin Hou,Licheng Liu,Hong He
Ce- or La-doped Cu/SSZ-13 catalysts were prepared by a hydrothermal method and Cu, Ce or La ions were incorporated through stepwise ion exchange. The catalyst activity was measured for the ammonia selective catalytic reduction reaction. The structure and composition of catalyst were characterized by using X-ray diffraction, scanning electron microscopy, inductively coupled plasma mass spectrometry solid-state NMR, NH 3 -TPD techniques, and the active components were examined by XPS and XANES . The results indicate that the Ce and La doping can both completely preserve the SCR activity of Cu/SSZ-13 above 300 °C, but there is also a decrease of activity below 200 °C. On the other hand, Ce doping is beneficial to the formation of framework aluminum , stabilizes molecular sieve framework and Cu active sites of Cu/SSZ-13, thereby improves the catalyst hydrothermal stability. But La doping will decrease the amount of framework aluminum and Cu active sites of Cu/SSZ-13 after hydrothermally aging, even destroy zeolite CHA structure. This is quite harmful to the catalyst hydrothermal stability.
研究领域:
催化
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环境化学
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材料科学
✓ 已验证
DOI
高影响因子
Catalysts
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2020
·Vol. 10
·期 11
·1329
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IF 3.52
Shijie Hao,Yandi Cai,Chuanzhi Sun,Jingfang Sun,Changjin Tang,Lin Dong
Monolithic Mn-Fe-Ce-Al-O catalyst with honeycomb cordierite ceramic as a carrier was reported for the first time for low temperature deNOxapplication. In the reaction of selective catalytic reduction (SCR) of NO with NH3, a NO conversion of above 80% at 100 °C was obtained. Notably, the catalyst also showed excellent resistance against SO2and H2O. About 60% NO conversion was maintained after successive operation in the mixed stream of SO2and H2O for 168 h. The Brunner−Emmet−Teller (BET) measurement, SEM, EDS, thermogravimetric analysis (TG), FT-IR, and XPS results of the used catalysts indicated that certain amounts of ammonium sulfate was formed on the surface of the catalyst. XPS results revealed that partial of Fe2+was oxidized to Fe3+during the reaction process, and Fe2+species have strong redox ability, which can explain the decrease in activity after reaction. In addition, SO2and H2O induced a transformation of Ce from Ce4+to Ce3+on the surface of the catalyst, which increased the amount of chemisorbed oxygen. Owing to these factors, the addition of Ce and Fe species contributes to excellent resistance of the catalyst to SO2and H2O.Keywords:honeycomb catalyst;Mn-Fe-Ce-Al-O;low temperature denitration;water and sulfur resistance
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED ENERGY
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2022
·
IF 11.446
Wenshuo Hu,Yu Zhang,Xiaoxiang Wang,Weihong Wu,Hao Song,Yang Yang,Shaojun Liu,Chenghang Zheng,Xiang Gao
Ceria has absorbed extensive interests in functioning as catalysts for low-temperature (LT) selective catalytic reduction (SCR) of NOx due to its abundant surface oxygen species and salient redox property. The mechanistic interpretations of how such redox property contributes to its LT-SCR activity, however, still remain debated. Here, we use a model tungsten-promoted ceria catalyst (WO 3 /CeO 2 ), known as preeminent in LT-SCR reactions, and combine steady-state kinetic, structural characteristic and in situ spectroscopic experiments with theoretical treatments to reveal the mechanistic connections between NO oxidative activation and LT-SCR turnovers. We show that, compared with NO oxidation to NO 2 , NO oxidative activation to nitrite intermediates is both kinetically and thermodynamically more favorable; surface nitrate species are not detected in the present case, indicating their more difficult formation than nitrites. All these results thus suggest the prevalence of NO activation to nitrites over NO to nitrates or oxidation to NO 2 and subsequent occurrence of fast SCR in the WO 3 /CeO 2 -catalyzed LT-SCR reaction. These findings progress the understanding of LT-SCR reaction mechanism on CeO 2 -based catalysts and convey a detailed perspective of different reaction intermediates and their consequences for LT-SCR turnovers, which may contribute to the rational design of catalysts towards further improved LT-SCR activity.
研究领域:
催化化学
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CHEMICAL ENGINEERING
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2022
·
IF 3.898
Yaoyao Peng,Lei Song,Siru Lu,Ziyu Su,Kui Ma,Siyang Tang,Shan Zhong,Hairong Yue,Bin Liang
The significant decrease of acid sites caused by alkali metal poisoning is the major factor in the deactivation of commercial V 2 O 5 -WO 3 /TiO 2 NH 3 -SCR catalysts. In this work, the solid superacid SO 4 2− -TiO 2 modified by sulfate radicals, was selected as the catalyst support, which showed superior potassium resistance. The physicochemical properties and K-poisoning resistance of the V 2 O 5 -WO 3 /SO 4 2− -TiO 2 (VWSTi) catalyst were carried out by XRD, BET, H 2 -TPR, NH 3 -TPD, XPS, in situ DRIFTS and TG. The results pointed out that the introduction of SO 4 2− significantly increased the NH 3 -SCR catalytic activity at high temperatures, with an exceptionally high NO x conversion over 90% between 275 °C and 500 °C. When 0.5% (mass) K 2 O was doped on the catalysts, the catalytic performance of the traditional V 2 O 5 -WO 3 /TiO 2 (VWTi) catalyst decreased significantly, while the VWSTi catalyst could still maintain a NO x conversion over 90% in the range of 300–500 °C. The characterizations suggested that the support of SO 4 2− -TiO 2 greatly increased the number of acidic sites, thereby enhancing the adsorption capacity of the reactant NH 3 . The results above demonstrated a potential approach to achieve superior potassium resistance for NH 3 -SCR catalysts using solid superacid.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
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2023
·
IF 7.4
Yiqing Zeng,Weilong Rong,Shule Zhang,Qin Zhong,Zhaoxiang Zhong
Synergistic control of multiple pollutants has high benefits during the control of emissions from fuel utilization, and catalysis can contribute to efficient removal of multiple pollutants. In this work, Ti species regulated CuO/CeO 2 (Cu/Ce) catalyst was constructed to efficient simultaneous NH 3 -SCR denitration and CO oxidation under oxygen-rich conditions. It is found that the introduction of Ti species into Cu/Ce catalyst induces the formation of three-dimensional pore structure and promotes the phase transition from crystalline to amorphous, which significantly enhances the specific surface area and the dispersion of CuO and CeO 2 . The well dispersed CuO and CeO 2 species provide a larger number of adsorbed sites for CO and NO and enhance the Cu-Ce interaction, which can contribute to reducing the competitive adsorption between CO and NO and the formation of a richer surface oxygen vacancies. Owing to above improvements, the Ti species regulated Cu/Ce catalyst can achieve more than 90% removal efficiency of NO x and CO at 148–218 °C, and the active temperature windows widened by 36 °C in comparison with Cu/Ce catalyst. Through this work, we expect to shed some light on the synergistic control of CO and NO x under oxygen-rich conditions.
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2016
·
IF 2.628
Jixing Liu,Jian Liu,Zhen Zhao,Weiyu Song,Yuechang Wei,Aijun Duan,Guiyuan Jiang
A series of meso-microporous copper-supporting chabazite molecular sieve (Cu-SAPO-34) catalysts with excellent performance in low-temperature ammonia selective catalytic reduction (NH 3 -SCR) have been synthesized via a one-pot hydrothermal crystallization method. The physicochemical properties of the catalysts were characterized by scanning electron microscopy, transmission electron microscopy , N 2 adsorption-desorption measurements, X-ray diffraction, 27 Al magic angle spinning nuclear magnetic resonance , diffuse reflectance ultraviolet-visible spectroscopy, inductively coupled plasma-atomic emission spectroscopy, X-ray photoelectron spectroscopy , temperature-programmed reduction measurements, and electron paramagnetic resonance analysis. The formation of micro-mesopores in the Cu-SAPO-34 catalysts decreases diffusion resistance and greatly improves the accessibility of reactants to catalytic active sites. The main active sites for NH 3 -SCR reaction are the isolated Cu 2+ species displaced into the ellipsoidal cavity of the Cu-SAPO-34 catalysts.
研究领域:
材料化学
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环境催化
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多孔材料
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工业催化
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能源与环境科学
✓ 已验证
DOI
高影响因子
iScience
·
2025
·
IF 4.1
Zhenzhen Guan,Yuanbin Xia,Dongchen Hang,Gan Chen,Mengyan Zhang,Zhihai Cheng,Xinxia Ma,Jiang Wu
In this study, a series of CoMnFeAl-layered double oxide (LDO) catalysts supported on multi-walled carbon nanotubes (MWCNTs)/titanium dioxide nanowires (TiO 2 NWs) were synthesized via the hydrothermal method. The catalytic performance of the synthesized catalysts was evaluated by the activity tests, and the characterizations and morphologies were measured by using X‐ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), Brunauer-Emmett-Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption of ammonia (NH 3 -TPD), temperature-programmed desorption of sulfur dioxide (SO 2 -TPD), temperature-programmed reduction of hydrogen (H 2 -TPR), and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The results demonstrated that both CoMnFeAl-LDO/CNT and CoMnFeAl-LDO/TiO 2 NW catalysts achieved 100 % NO x conversion within their optimal temperature ranges and exhibited excellent sulfur resistance. Morphological studies revealed that the introduction of CNTs or TiO 2 NWs effectively mitigated the aggregation and stacking of LDHs during calcination, resulting in enhanced dispersion of active components. Moreover, these modifications increased surface acidity, redox capability, and SO 2 tolerance of the CoMnFeAl-LDO catalyst. The in situ DRIFTS results indicated that the SCR reactions over CoMnFeAl-LDO/CNT and CoMnFeAl-LDO/TiO 2 NW followed both the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) mechanisms. This study highlighted the potential of CNTs/TiO 2 NWs to modify CoMnFeAl-LDO catalysts, offering insights for the design of efficient and sulfur-resistant catalysts to address stringent environmental regulations.
研究领域:
环境催化
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材料化学
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大气污染控制
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表面科学
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工业催化
✓ 已验证
产品关联
DOI
PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
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2018
·Vol. 20
·期 35
·22744-22752
·
IF 3.906
Yiqing Zeng,Yanan Wang,Shule Zhang,Qin Zhong
In this paper, black TiO2 without adding active components was developed for NH3-SCR-DeNOx. The catalytic activity tests showed that the NO removal efficiency of black TiO2 was always greater than 90% at 330–390 °C, which almost reached that of the commercial NH3-SCR-DeNOx catalyst. XRD, UV-vis, TG, EPR, XPS, H2-TPR, DFT and NH3-TPD analyses were carried out to study the structure–effectiveness relationship. We found that a large number of oxygen vacancies were formed over the black TiO2 surface. It was not only promoted the adsorption of NH3via direct (oxygen vacancies as Lewis acid sites for NH3 adsorption) and indirect (oxygen vacancies promote the formation of surface hydroxyl groups, which are Brønsted acid sites for NH3 adsorption) forms, but also improved the redox properties by promoting the reduction of Ti4+ to Ti3+. These changes lead to the superior catalytic activity of black TiO2 for NH3-SCR-DeNOx. Additionally, an in situ DRIFT study demonstrated that the NH3-SCR-DeNOx reaction over black TiO2 occurred via the Eley–Rideal (E–R) mechanism. Finally, the catalytic stability and resistance to H2O and SO2 of the black TiO2 catalyst were studied, and it showed good performances. This study offered new and important insights into the understanding of the role of oxygen vacancies in determining the physical and chemical properties of catalysts.
研究领域:
环境催化
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材料科学
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物理化学
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大气污染控制
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表面科学
✓ 已验证
DOI
高影响因子
Journal of the Taiwan Institute of Chemical Engineers
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2022
·
IF 5.477
Kaiwen Ni,Yuewang Peng,Geyu Dai,Huawang Zhao,Zhiwei Huang,Xiaomin Wu,Guohua Jing,Wei Feng,Ye Yuan
Background Ammonia bisulfate (ABS) deposition on the active sites of the catalyst surface is the main reason for SO 2 poisoning in low-temperature NH3-selective catalytic reduction (SCR). Accelerated ABS decomposition efficiently enhances the SO 2 resistance. Methods In this work, ceria was specifically chosen to decorate V 2 O 5 -WO 3 /TiO 2 catalyst (Ce-VW/Ti) to activate ABS decomposition in low-temperature NH 3 -SCR. Significant findings The optimal 7Ce-VW/Ti catalyst accelerated the decomposition of ABS and had superior SO 2 tolerance at 250°C. The additive CeO 2 improved the specific surface area and surface acidity, favoring the NH 3 -SCR catalytic activity. ABS was preferentially deposited on the additive CeO 2 on the surface of the 7Ce-VW/Ti catalyst and generated cerium sulfate, eventually protecting the active V 2 O 5 sites and TiO 2 support. Moreover, high quantity of V 5+ and charge transfer between active species V 2 O 5 and support TiO 2 could be maintained due to CeO 2 protection, subsequently maintaining the high NH 3 -SCR performance and enhancing the SO 2 tolerance.
研究领域:
催化
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环境科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2021
·
IF 8.128
Yifan Li,Yaqin Hou,Yongzhao Zhang,Yatao Yang,Zhanggen Huang
Surface interface regulation is an important research content in the field of heterogeneous catalysis. To improve the interface interaction between the active component and matrix, tremendous efforts have been dedicated to tailoring the morphology, size, and structure of composite catalysts. In this work, we report a confinement strategy to synthesize a series of core-shell catalysts loaded with metal oxides on titania nanotubes (TNTs), which were applied to the selective catalytic reduction of NO x with ammonia. Interestingly, the core-shell catalyst with confinement of TNTs exhibited the remarkable activity at low temperature region, N 2 selectivity and sulfur tolerance. Benefiting from the superior interfacial confinement characteristic of TNTs and Fe 2 O 3 , strong component interactions, the surface acid sites and strong oxidizability of MnO x were properly regulated, thus obtained the outstanding activity, N 2 selectivity and provide chemical protection to effectively prevent SO 2 poisoning. As far as the reaction mechanism, we found that the adsorption and reactivity of Lewis acid sites were the dominant factors affecting the activity in the NH 3 -SCR process by in situ DRIFT spectra. In general, our work provides an innovative strategy for constructing an TNTs-enwrapped nanocomposite with nano-confinement and core-shell structure to improve the low temperature SCR process.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
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2023
·
IF 22.1
Wang Song,Qianni Cheng,Li Han,Jiawei Ji,Yandi Cai,Wei Tan,Jingfang Sun,Changjin Tang,Lin Dong
Manganese oxide-based catalysts exhibit excellent low-temperature denitration efficiency, making them potential candidates for application. Herein, the relationship between reaction stability and phase structure for MnO 2 , Mn 2 O 3 and Mn 3 O 4 was disclosed. The NO conversion for Mn 2 O 3 drastically reduced after 120 h reaction, while minor decline was detected for MnO 2 and Mn 3 O 4 . Based on dedicate qualitative and quantitative analyses on the deposits over catalyst surface, deactivation trigged by ammonium nitrate (AN) deposition was confirmed. Different from penta-coordinated Mn 4+ on MnO 2 (110) and tri-coordinated Mn 2+ , penta-coordinated Mn 4+ on Mn 3 O 4 (101), the unique tetra-coordinated Mn 3+ on Mn 2 O 3 (200) could stabilize the nitrates and make it difficult to be removed via decomposition or reaction and accumulate continuously, which resulted in the significant deactivation. This research could not only unveil the poisoning mechanism of MnO x based catalysts, but also provide new insights into the relationship between the catalytic stability and surface Mn-O microstructure.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2014
·
IF 5.9
Lei Chen,Zhichun Si,Xiaodong Wu,Duan Weng
A CuO–CeO2–TiO2 catalyst for selective catalytic reduction of NOx with NH3 (NH3-SCR) at low temperatures was prepared by a sol–gel method and characterized by X-ray diffraction, Brunner–Emmett–Teller surface area, ultraviolet–visible spectroscopy, H2 temperature-programmed reduction, scanning electron microscopy and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS). The CuO–CeO2–TiO2 ternary oxide catalyst shows excellent NH3-SCR activity in a low-temperature range of 150–250 °C. Lewis acid sites generated from Cu2+ are the main active sites for ammonia activation at low temperature, which is crucial for low temperature NH3-SCR activity. The introduction of ceria results in increased reducibility of CuO species and strong interactions between CuO particles with the matrix. The interactions between copper, cerium and titanium oxides lead to high dispersion of metal oxides with increased active oxygen and enhanced catalyst acidity. Homogeneously mixed metal oxides facilitate the “fast SCR” reaction among Cu2+–NO, nitrate (coordinated on cerium sites) and ammonia (on titanium sites) on the CuO–CeO2–TiO2 catalyst at low temperatures.
研究领域:
环境催化
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材料化学
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表面科学
·
化学工程
·
大气污染控制
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）