Journal of Cleaner Production
·
2022
·
IF 11.072
Jiajin Huang,JiaYu Chen,Jinze Yao,Siyao Zhao,Xingbei Wu,Qibin Xia
The challenge for selective catalytic reduction (SCR) of NO x with NH 3 is to improve de-NO x activity at low temperatures while simultaneously improving the tolerance of catalysts towards SO 2 poisoning. Herein, V and Ce oxides were loaded on deactivated SCR catalysts subjected to acid pickling (CAT) via impregnation to recover de-NO x activity. The resulting V–Ce@CAT catalyst exhibited 85–95% NO x conversions over a wide temperature window of 200–450 °C while conversions of only 40–78% over the same temperature range were observed with CAT (spent catalyst treated with acid). Interestingly, in addition to the high tolerance towards SO 2 displayed by V–Ce@CAT, the catalyst exhibited improved reactivity after the introduction of 200 ppm SO 2 , with the NO x conversion increasing from 80% to 87%. The results indicated that a kinetic equilibrium was reached between the formation and decomposition rates of Ce 2 (SO 4 ) 3 on V–Ce@CAT which prevented the accumulation of surface sulfate species, thereby protecting the main active species V from catalytic inactivation. Furthermore, in situ DRIFTS revealed that the NH 3 -SCR reaction pathway of V–Ce@CAT follows the L-H mechanism.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
·
IF 3.764
Wenshuo Hu,Renzhi Zou,Yi Dong,Yu Zhang,Mingchu Ran,Qi Xin,Yang Yang,Hao Song,Weihong Wu,Shaojun Liu,Chenghang Zheng,Xiang Gao
Enhancement of the low-temperature (LT) performance of selective catalytic reduction (SCR) of NOx with NH3 has been a spotlight in environmental catalysis. Here, we use a bifunctional catalytic system mixing V–W/Ti with an oxidative component, i.e., MnOx/CeO2, to achieve both improved LT-SCR activity and N2 selectivity. An integrated approach of steady-state kinetic measurements, chemical trapping techniques, time-resolved in situ FTIR spectroscopy, and density functional theory (DFT) calculations reveals that such a synergistic enhancement is at a short distance and is significant when V–W/Ti and MnOx/CeO2 are in intimate contact. These findings further suggest a bifunctional LT-SCR pathway mediated by a short-lived, mobile nitrite-precursor intermediate, which is facilely generated on the oxidative component and then communicates with the adjacent SCR phase through reacting with the abundant NH3 adsorbates there. Assembling such a mechanism with commercial SCR catalysts, accordingly, acts as a promising way to enhance the LT-SCR performance.
研究领域:
环境催化
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材料科学
✓ 已验证
DOI
高影响因子
NANO
·
2019
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IF 1.293
Qian Sun,Chun Zeng,Meng-Meng Xing,Bo Chen,Dan Zhao,San-Guo Hong,Ning Zhang
Deliberately engineering oxide composites on constructing and manipulating interactive structures particularly in surface layers was highly desirable for heterogeneous catalysis. Herein, upon the redox replacement reaction between Ce(IV) precursor (Ce(NO 3 ) 6 2 − ) and Cu 2 O nano-substrate, an attempt to directly engineer the surface structure of Cu-based substrate was performed by the Ce(IV)–Cu 2 O etching-embedding process, then the obtained powders were thermo-treated to get a series of Ce–O–Cu catalysts with different Ce:Cu molar ratios for NH 3 selective catalytic reduction (NH 3 -SCR) of NO. Characterized by ICP-OES, XRD, Raman, XPS, SEM, BET, H 2 -TPR, NO- and NH 3 -TPD measurements, it was demonstrated that the Cu–O–Ce catalysts were structured as CuO matrix with an interactive surface composed by co-present Cu(I)–Cu(II) and Ce(III)–Ce(IV) species, even the introduction of Ce was confined in a quite low loading range (0.83–2.3 wt.%); such a surface exhibited the distinct synergistic effect with positively manipulated physical-chemistry properties such as active site distributions, redox features and surface reactivity compared to pure CuO and traditional Cu–Ce composite catalyst, leading to attractive catalytic performance such as ≥ 9 0 % NO conversion with ≥ 9 5 % N 2 selectivity and the two-fold TOF enhancement versus traditional catalysts, even SO 2 was present in reactant mixture on well-manipulated catalyst (Ce loading at 1.6 wt.%) These results indicated that the etching-embedding strategy illuminated in this work could be referred as a feasible method to directly engineer and construct interactive oxide composite surface for advanced application as well as current efficient Ce–O–Cu catalytic interface for heterogeneous catalysis.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
AICHE JOURNAL
·
2022
·Vol. 68
·期 11
·e17834
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IF 4.167
Wuyuan Liu,Zhaoying Wang,Ming Sun,Jiajian Gao,Lifeng Wang,Zihan Gao,Yingying Xu,Xiangyun Zhao,Cheng Zhang,Lin Yu
A series of CeO 2 modified Cu-SSZ-13 monolith catalysts were prepared by embedding CeO 2 into the washcoat of Cu-SSZ-13 monolith catalyst through solvent combustion method. These CexCu-SSZ-13 catalysts were studied in the selective catalytic reduction (SCR) of NO with NH 3 , among which the Ce2Cu-SSZ-13 catalyst exhibited the best low-temperature activity, hydrothermal stability, and sulfur resistance. The physicochemical properties of the catalysts were characterized using multiple methods. Results showed that the acidity, redox capacity, and ammonia adsorption capacity significantly enhanced after CeO 2 modification, thus leading to the high performance of Ce2Cu-SSZ-13 catalyst. Furthermore, the introduction of CeO 2 induced the fast SCR reaction by promoting the oxidation of NO to NO 2 . Analog calculation suggested that the porous structure generated via solvent combustion in the washcoat effectively increased the diffusion rate of reaction. In situ diffuse reflectance infrared Fourier transform spectroscopy ( in situ DRIFT) analysis showed that Brønsted acid sites were the main active center and the reaction followed Eley–Rideal mechanism.
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
Journal of Environmental Chemical Engineering
·
2023
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IF 7.7
Chenhui Hu,Chunhong Liu,Kaimin Du,Chengkai Pang,Zuoxi Zhuo,Qiangsheng Gao
An energy-saving catalyst 4%Fe/Ce-Mn-TiO 2 was prepared via a simple one-step impregnation-annealing process and used as a denitration catalyst at low temperature (≤180 °C) and high water content (∼20%). The results show that 4%Fe/Ce-Mn-TiO 2 catalyst exhibits good low-temperature catalytic activity and water resistance attributed to its highly dispersed metal oxide species, more surface-adsorbed oxygen and high stability of particles. The denitrification efficiencies of 4%Fe/Ce-Mn-TiO 2 catalyst are 90% (5% H 2 O) and 70% (20% H 2 O) at 170 ℃ respectively, which are superior to the commercial vanadium catalyst in service usually needs heating up to 220 ℃.
研究领域:
环境科学
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催化
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化学工程
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2023
·Vol. 13
·期 18
·5435-5448
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IF 5
Xinyue Hu,Jialing Chen,Shaokang He,Tingyu Liang,Shenke Zheng,Lijun Lu,Chenxi Hao,Kaixin Chen,Tingting Li,Lan Yi,Li Guo,Xiaoqin Wu
Three OP-Fe-FER-x zeolites (with an FER structure) synthesized by a one-pot method with different Si/Al ratios (x = Si/Al =10–30) and similar iron contents (5.4–5.6 wt%) were compared with commercial IM-Fe/SSZ-20 zeolite (with a CHA structure) prepared by an incipient wetness impregnation method to investigate their catalytic activity and hydrothermal stability for the selective catalytic reduction reaction of NOx with NH3 (NH3-SCR). For both fresh (without hydrothermal aging treatments) and aged (with hydrothermal aging treatments) zeolites, the NOx conversions of OP-Fe-FER-x zeolites are much higher than that of IM-Fe/SSZ-20 zeolite, suggesting that the OP-Fe-FER-x zeolites are better catalysts for NH3-SCR than the commercial IM-Fe/SSZ-20 zeolite. Compared with the fresh zeolites, the NOx conversions of all four aged zeolites decrease in the low-temperature range (100–300 °C), while they increase at high temperatures (450–550 °C) to different extents. Based on XRD, N2 physisorption, NH3-TPD, UV-vis, XPS and H2-TPR experiments, the hydrothermal aging process of the OP-Fe-FER-x zeolites is depicted, which consists of partial collapse of the zeolite framework, removal of framework aluminum and iron atoms, and transformation and aggregation of iron species. Detailed characterization reveals that the OP-Fe-FER-x zeolites are more stable than the IM-Fe/SSZ-20 zeolite during the hydrothermal aging treatments. The obvious decline of NH3-SCR catalytic activity for the aged zeolites in the low-temperature range is mainly attributed to the transformation and aggregation behaviors of active isolated Fe3+ species. As for the increase of NH3-SCR activity for the aged zeolites at the high temperatures (450–550 °C), it is mainly attributed to the suppression of the NH3 oxidation side reaction due to the deteriorated NH3 storage capacity because of the loss of massive acid sites during the hydrothermal aging treatments.
研究领域:
化学工程
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
Advances in Materials Science and Engineering
·
2019
·
IF 1.399
Zhuo Yao,Dianli Qu,Yuxiang Guo,Yujing Yang,Hong Huang
Novel catalysts with high activity for the selective catalytic reduction of NO with NH3 (NH3-SCR) at low temperatures are highly demanded. In this study, mixed-node metal-organic frameworks (MOFs), e.g. Mn@CuBTC with controlled Mn composition in Cu3(BTC)2, were fabricated using postsynthetic exchange method and their structural characteristics and catalytic performances for NH3-SCR reaction were assessed. A series of analyses in terms of structure, surface morphology, texture, and chemical state determined that Mn ions were successfully incorporated into the Cu3(BTC)2 crystal lattice as well as adsorbed on the walls of nanopores in the framework. The pore sizes can be finely tuned in the presence of Mn ions in the cages, which significantly suppressed water adsorption. The NH3-SCR activity of Mn@CuBTC exhibited nearly 100% NOx conversion rate in the temperature range (230–260°C). The superior NH3-SCR performance is attributed to the proper pore sizes, reduced water content, and the synergistic effect between manganese and copper ions in the MOF structure, which enhanced NH3 bound to the active Lewis sites.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2022
·
IF 4.889
Wuyuan Liu,Zihan Gao,Ming Sun,Jiajian Gao,Lifeng Wang,Xiangyun Zhao,Runnong Yang,Lin Yu
A series of Cr α Mn β CeTiO x catalysts were prepared using one-pot precipitation method and evaluated for the selective catalytic reduction (SCR) of NO with ammonia. Among the catalysts prepared, the Cr 0.006 Mn 0.05 CeTiO x catalyst exhibited the highest low-temperature activity and widest activity window (＞90% NO conversion at 160–425 °C) as well as outstanding sulfur resistance. The catalysts were characterized using XRD, NH 3 /NO/SO 2 + O 2 -TPD, XPS, in situ DRIFT, and so on. The amorphous Cr 0.006 Mn 0.05 CeTiO x catalyst had a larger specific surface area, high ammonia adsorption and strong acidity, resulting in an improved catalytic activity. A high ratio of surface adsorption oxygen and Ce 3+ promoted the formation of NO 2 , a key intermediate gas in the fast SCR reaction. Furthermore, in situ DRIFT showed that the SCR reaction followed the Eley Rideal and Langmuir Hinshelwood mechanisms. Moreover, the synergetic effect of Cr and Mn inhibited the accumulation of hydrogen sulfate or sulfate considerably.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS LETTERS
·
2023
·
IF 2.8
Wang Yanghui,Jin Luyao,Xu Xintao,Li Jiaying,Fan Kaihao,Hu Bo,Shen Yi,Liu Xuesong
In this paper, MnO x /TiO 2 catalysts with different manganese contents were prepared by using vacuum over-impregnation method to support manganese on TiO 2 support. However, the activity temperature window was narrow and the denitrification efficiency was only 265–365 °C in the temperature zone above 80%. Therefore, doping W was used to improve the high temperature activity and broaden the activity temperature window. The experimental results show that the active temperature window of the catalyst is expanded to 260–550 °C when doping 20%WO 3 . The effects of tungsten doping on the structure and surface properties of the catalysts were investigated by XRD, TEM, Raman, XPS, H 2 -TPR and NH 3 -TPD. It is found that the increase of manganese content would increase the ratio of Mn 4+ and O α , and then improve the NH 3 -SCR activity at low temperature. Tungsten doping can provide more strong acid sites and improve the high temperature activity of the catalyst by inhibiting the oxidation of ammonia. Graphical Abstract
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY
·
2021
·
IF 6.064
Bichun Huang,Hansun Fang,Huajun Huang,Meijuan Lu,Chenglong Yu
A one-pot synthetic method was used to prepare copper (Cu)-modified manganese (Mn)-rich MnSAPO-34 catalysts, which were then used for NO x removal from stationary-source flue gas. The addition of Cu to these Mn-rich MnSAPO-34 catalysts significantly enhanced their low temperature (LT) selective catalytic reduction (SCR) activity and H 2 O resistance. The Mn 0.4 Cu 0.05 SAPO-34 catalysts demonstrated excellent LT NH 3 -SCR activity, with NO x removal being >90% from 160 to 300 °C. In addition, Mn 0.4 Cu 0.05 SAPO-34 catalysts exhibited high H 2 O resistance. This excellent performance was ascribed to strong synergistic effects between Mn 4+ and isolated Cu 2+ species in Mn 0.4 Cu 0.05 SAPO-34 catalysts, leading to suitable redox ability. The results of in situ FT-IR analysis indicated that LT-SCR reactions mainly proceeded by an Eley–Rideal reaction pathway at 200 °C in Cu-modified manganese-rich MnSAPO-34 catalysts. Thus, Mn 0.4 Cu 0.05 SAPO-34 was considered as a promising candidate for NO x removal from flue gas of stationary sources at low temperatures.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Journal of Physical Chemistry C
·
2024
·
IF 3.3
Fumei Wang,Qi Cai,Xinhua He,Boxiong Shen,Leila Negahdar,Shuo Feng,Andrew M. Beale
Cu/SAPO-34 catalysts have been widely used for the reduction of NOx from diesel exhaust by ammonia-selective catalytic reduction (SCR). Sulfur poisoning remains a challenge for Cu/SAPO-34 catalysts in NH3–SCR, restricting its application. In this study, Cu/SAPO-34 samples containing a mixture of Cu species comprising isolated Cu2+ located in the 6MR, Cu(OH)+ in 8MR, CuO clusters/nanoparticles, and Cu+ species were prepared. The Cu speciation during SO2 and hydrothermal aging of Cu/SAPO-34 SCR catalysts was subsequently studied. While hydrothermal aging had little effect on catalytic activity, the sulfur-aged sample exhibited deterioration in NH3–SCR activity over the temperature range of 100–575 °C. The breakage and collapse of the zeotype framework and chemical deactivation of the Cu/SAPO-34 catalyst after exposure to SO2 and H2O took place. A combination of X-ray photoelectron spectroscopy (XPS) and TGA-DT-DSC revealed the presence of ammonium bisulfate, copper bisulfate/sulfate, aluminum sulfate, and sulfuric acid after SO2 and H2O copoisoning under SCR conditions. Furthermore, Cu(OH)+ tended to migrate to form isolated Cu2+ and Cu+, as well as agglomerate to form CuO particles. Density functional theory (DFT) calculations revealed that SO2 and O2 could readily be absorbed by CuO particles to form stable copper bisulfate/sulfate species with the following order of preference: CuO > Cu+ > Cu2+ > Cu(OH)+. In contrast, Cu(OH)+ was less prone to be poisoned by easily releasing SO3 than other Cu species sites.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Wen Luo,Jing Rong,Wanxia Zhao,Keke Kang,Lulu Long,Xiaojiang Yao
CeO 2 –TiO 2 catalysts with four different morphologies were successfully synthesized by a hydrothermal method and tested for selective catalytic reduction of NO x with NH 3 (NH 3 –SCR). For the four catalysts, CeO 2 –TiO 2 nanocubes (CT–NC) and nanorods (CT–NR) preferentially exposed {1 0 0} and {1 1 0} facets, respectively; furthermore, nanosheets (CT–NS) and nanospheres (CT–NH) mainly exposed {1 1 1} facet. Interestingly, CT–NH catalyst showed the best NH 3 –SCR performance and the NO x conversion exceeded 97% at 325 °C. Through a series of characteristic methods manifested that the short–range ordered structure of Ce–O–Ti in CT–NH catalyst provided stronger surface acidic sites to promote the high–temperature activity. Moreover, the abundant Ce 3+ species and appropriate reduction ability on {1 1 1} facet of CT–NH catalyst also caused outstanding de NO x activity. Reaction mechanism study showed that the Langmuir–Hinshelwood (L–H) mechanism and Eley–Rideal (E–R) mechanism existed simultaneously on all catalysts in NH 3 –SCR reaction. Meaningfully, two types of E–R mechanism were present on CT–NH catalyst, while L–H mechanism was dominant.
研究领域:
催化化学
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）