CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Chuanzhi Sun,Hao Liu,Wei Chen,Dezhan Chen,Shuohan Yu,Annai Liu,Lin Dong,Shuai Feng
A series of Sm- and/or Zr-doped MnO x -TiO 2 catalysts were prepared, and the catalysts exhibited better N 2 selectivity and SO 2 resistance than the undoped MnO x -TiO 2 catalyst for the selective catalytic reduction of NO by NH 3 (NH 3 -SCR). The reasons for the good N 2 selectivity and SO 2 resistance of the catalysts were proposed. X-ray photoelectron spectroscopy (XPS) combined with density functional theory (DFT) calculations suggested that electron transfer between the manganese and samarium species by Mn 4+ + Sm 2+ ↔ Mn 3+ + Sm 3+ redox cycles occurred in the Sm-containing catalysts. Furthermore, electron transfer from Sm 2+ to Mn 4+ suppressed electron transfer from NH 3 to Mn 4+ , inhibiting the formation of NH 2 or NH. Thus, the pathway for NH generation was removed, and the reaction of 2NH + 4NO → 3N 2 O + H 2 O was prevented. Consequently, the N 2 selectivity of the NH 3 -SCR reaction was enhanced. In situ diffused reflectance infrared Fourier transform spectroscopy ( in situ DRIFTS) combined with thermogravimetry, differential scanning calorimetry and mass spectrometry (TG-DSC-MS) results revealed that the deposition rate of sulfate species decreases after Sm doping, which was also attributed to the suppressed electron transfer from SO 2 to Mn 4+ , i.e., the oxidation of SO 2 to SO 3 . Thus, the catalysts exhibited better SO 2 resistance.
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
CHEMICAL ENGINEERING JOURNAL
·
2022
·
IF 16.744
Yanke Yu,Desheng Wei,Zhaojian Tong,Jinxiu Wang,Jinsheng Chen,Chi He
Ammonia (NH 3 ) is a critical component causing environmental problems like haze and water pollution. Selective catalytic oxidation of ammonia (NH 3 -SCO) to N 2 and H 2 O is a promising method to abate NH 3 emission. However, inferior SO 2 tolerance is still a tremendous challenge to be conquered for present NH 3 -SCO catalysts regarding practical applications. Application of materials which was difficult to be sulfated by SO 2 should be an effective way to solve this problem. Here, a ReO x -CuSO 4 /TiO 2 catalyst which coupled the advantages of ReO x (Rhenium oxides, supplying highly active adsorbed surface oxygen enhancing NH 3 -SCO reaction) and CuSO 4 (providing Brønsted acid sites inhibiting the formation of N 2 O) was rationally fabricated. Results indicated that ReO x -CuSO 4 /TiO 2 catalyst exhibited excellent catalytic performance in NH 3 -SCO with almost 100% of NH 3 oxidized at 300 °C (N 2 selectivity as high as 96%). Crucially, the composite catalyst exhibited incredible activity and stability under harsh reaction conditions toward SO 2 (600 ppm) and H 2 O (4.0 vol%) owing to the superior inhibition capability for SO 2 adsorption. In situ DRIFTS, in situ Raman and in situ XPS demonstrated that the NH 3 -SCO reaction over ReO x -CuSO 4 /TiO 2 catalyst mainly obeyed a N 2 H 4 reaction mechanism and oxidation–reduction circle between Re 7+ and Re 6+ played a vital role. Moreover, SO 2 would not affect this reaction mechanism on ReO x -CuSO 4 /TiO 2 catalyst. The knowledge and understanding reported could provide critical insights for the design and optimization of efficient materials for industrial NH 3 oxidative elimination.
研究领域:
催化化学
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环境科学
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材料科学
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产品关联
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2021
·
IF 5.706
Huansheng Tan,Shibo Ma,Xiaoyu Zhao,Yushi Li,Chen Zhao,Yujun Zhu
Bimetallic W a CeO x (a = 0.06, 0.12, 0.18, 0.24) catalysts were synthesized for selective catalytic reduction of NO x with NH 3 (NH 3 -SCR). The influences of W on structure, activity and surface properties were investigated by XRF, XRD, Raman, TEM, N 2 adsorption-desorption, H 2 -TPR, O 2 /NH 3 /SO 2 -TPD, XPS, and in-situ DRIFTS. The characterization results show that the W/Ce ratio has a great effect on the NH 3 -SCR activity. The different catalytic activities of W a CeO x are mainly attributed to the acidity change, especially the increase of B-acid content plays a major role in enhancing low temperature activity. W 0.18 CeO x exhibits excellent low-temperature NH 3 -SCR activity, SO 2 /H 2 O resistance and N 2 selectivity with a broad activity window (190–490 °C) with 5%H 2 O. Moreover, good activity window (235–460 °C) can be maintained even the catalyst treated with 5% H 2 O at 800 °C for 12 h, showing especial hydrothermal stability. Thus, it can be summarized that W 0.18 CeO x is regarded as outstanding catalyst for low-temperature NH 3 -SCR of NO.
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
PHYSICA SCRIPTA
·
2023
·Vol. 98
·期 11
·115027
·
IF 2.9
Deyang Ning,Jiaxiong He,Junqi Li,Zuoyu Liu,Renjie Liao,Yuanpei Lan,Fan Wang,Zhou Zou
In this work, three synthesis methods including photo-chemical, precipitation and hydrothermal were applied for synthesizing CeO2/TiO2 catalysts, and the catalytic performance including photodegradation degrees for organic pollutant and ammonia selective catalytic reduction (NH3-SCR) for NO removal were investigated. It was found that the photo-chemical synthesized CeO2-TiO2-PC exhibited the best photodegradation ability for methylene blue (MB), which had the degradation ratio of 91.21% and was approximately 23.92% higher than that with the matrix of rutile TiO2. The formed Ce-Ti heterojunction enhanced the separation of e−/h+ and further promoted the photocatalytic properties. Moreover, the CeO2-TiO2-PC, and the CeO2-TiO2-P which synthesized by the precipitation method showed better NH3-SCR properties than that of hydrothermal synthesized CeO2-TiO2-H below 300 °C, while the CeO2-TiO2-H owned an outstanding NH3-SCR performance above 300 °C. The difference on the NH3-SCR properties may be major attributed to the acid sites, pore structures and surface areas on the surface of different catalysts.
研究领域:
环境科学
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材料科学
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催化
✓ 已验证
DOI
高影响因子
Surfaces and Interfaces
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2024
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IF 5.7
Chengzhi Wang,Zhenbang Tian,Weiqing Huang,Jingyuan Hu,Xing Xing
Owing to the different reaction properties and deactivation mechanisms caused by the structural discrepancy of monolithic catalysts, abundant scientific results of powder or granular NH 3 -SCR catalysts have still not sufficiently robustly applied in recent years. Furthermore, minimal research has been focused on monolithic catalysts. As a result, this work prepared monolithic Mn-Fe-Ce/Al 2 O 3 catalysts by active component impregnation (ACI-Mn-Fe-Ce/Al 2 O 3 ) and precursor impregnation methods (PI-Mn-Fe-Ce/Al 2 O 3 ) and investigates the long-term SO 2 and H 2 O resistance of the catalysts. Compared with the PI-Mn-Fe-Ce/Al 2 O 3 catalyst, the monolithic ACI-Mn-Fe-Ce/Al 2 O 3 catalyst showed better performance. The catalytic activity follows a bell-shaped curve with an optimal performance at a drug loading of 5 %. The ACI-Mn-Fe-Ce/Al 2 O 3 catalyst exhibits long-term resistance to SO 2 and H 2 O and can still convert more than 70 % NO x after 168 h of SO 2 and H 2 O resistance test. Characterization of the ACI-Mn-Fe-Ce/Al 2 O 3 catalysts before and after the reaction showed that the reducibility decreased after the reaction, and more Mn 4+ was transformed into Mn 2+ to weaken the catalytic activity. However, more Fe 2+ and Ce 3+ were generated during the reaction, increasing the number of oxygen vacancies, oxygen defects, and hydroxyl-like groups, all of which would contribute to a certain extent to counteract the passivation effect of SO 2 on the catalysts. In situ DRIFTs analysis shows that the formation of surface sulfates has a minimal effect on the adsorption of NO, but it does affect the adsorption of coordinated NH 3 on Lewis acid sites. This work elucidates the deactivation details of Mn-Fe-Ce/Al 2 O 3 catalysts from the perspective of physicochemical properties, which provides a reference for the development of better low-temperature SO 2 -resistance catalysts for industrial applications.
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
CHEMICAL ENGINEERING JOURNAL
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2021
·
IF 13.273
Jiafan Cheng,Weiman Li,Xiaoze Wang,Haidi Liu,Yunfa Chen
This work is dedicated to fabrication of catalytic fibers for the process of selective catalytic reduction of NO x by NH 3 (NH 3 -SCR). By employing vanadium-titanium as main catalytic components, we investigated the effect of different inorganic supports (glass fiber, aluminum silicate fiber and quartz fiber), preparation methods (a sol–gel method and a hydrothermal method) and loading weight of V 2 O 5 on the NH 3 -SCR performance of catalytic fibers. The catalytic aluminum silicate fiber with 5% vanadium/titanium ratio prepared by a sol–gel method (denoted as V5Ti/AF) showed the best SCR and mass transfer performance. Characterization results indicated that a relatively large surface area, strong acidity, well-dispersed catalyst particles, and good redox and desorption properties derived from the interaction between catalytic components and supports all contributed to the good performance of V5Ti/AF. The pressure drop of catalytic fibers were measured, and the total pressure drop of catalytic fibers and de-dust ceramic membranes was much lower than previously prepared catalytic ceramic membranes, indicating their potential use in the co-processing of dust and gaseous pollutants.
研究领域:
环境科学
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材料科学
✓ 已验证
DOI
高影响因子
Molecular Catalysis
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2018
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IF 0
Sher Ali,Yushi Li,Tianrui Zhang,Syed ul Hasnain Bakhtiar,Xuesong Leng,Zhibin Li,Fulong Yuan,Xiaoyu Niu,Yujun Zhu
Citric acid method was employed to prepare a series of Nb-promoted Fe x -Nb 0 . 5- x -Ce 0.5 ( x = 0.45, 0.4, 0.35) oxides for selective catalytic reduction with NH 3 (NH 3 -SCR) of NO process. The structure, redox ability and reactivity of NH 3 and absorbed NO species on the catalysts were explored by using various characterization techniques such as X-ray diffraction (XRD), temperature program reduction with H 2 (H 2 -TPR), temperature program desorption of NH 3 (NH 3 -TPD), temperature program desorption of NO (NO-TPD), X-ray photoelectron spectroscopy (XPS) and in situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS). It was found that the Nb promoted Fe x -Nb 0 . 5- x -Ce 0.5 ( x = 0.45, 0.4, 0.35) oxides catalysts showed outstanding NH 3 -SCR of NO activity, excellent N 2 selectivity and remarkable SO 2 /H 2 O resistance, meanwhile, Fe 0.4 -Nb 0.1 -Ce 0.5 exhibited above 90% NO conversion in the range of 180–400 °C, together with near 100% N 2 selectivity. The characterization results point out that the excellent catalytic performance of Fe 0.4 -Nb 0.1 -Ce 0.5 can be ascribed to the strong interaction among Nb, Fe and Ce oxides. The strong interaction not only increases the BET surface area and redox ability of the catalyst, but also significantly improves the acid amount leading to the enhancement of the adsorption and activation of NH 3 , which is advantage of the reactivity of adsorbed nitrate together with the adsorbed NH 3 species.
研究领域:
催化化学
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环境科学
✓ 已验证
产品关联
DOI
ChemNanoMat
·
2023
·Vol. 9
·期 11
·e202300407
·
IF 3.8
Xinyu Han,Mengyao Bian,Kaijie Liu,Xin Yang,Daying Zheng,Xiangguang Yang,Yibo Zhang
Graphical Schematic diagram of the dominant mechanism of NH 3 -SCR reaction on CeCu/MCM-49 catalyst before and after poisoning. The L−H mechanism was dominant before poisoning. However, after alkali metal poisoning, NO x adsorption on the catalyst is inhibited, so the E−R mechanism dominates. NO x is a common atmospheric pollutant, and NH 3 -SCR technology efficiently purifies it. CeCuO x binary-oxide nanoparticles were synthesized and loaded onto acid MCM-49 molecular sieve with a large specific surface area to increase acid sites and disperse active sites of the catalyst. The optimized 35 % CeCu/MCM-49 catalyst effectively purified over 80 % of NO x in the temperature range of 200–500 °C and demonstrated excellent resistance to alkali metals, such as K, Na, and Ca. Even after K poisoning, it still removed over 80 % of NO x in the range of 200–450 °C. Various characterization methods, including XRD, FT-IR, TEM, and N 2 isotherm adsorption-desorption tests, confirmed the structure of the catalyst remained intact after poisoning with no substance change, nor agglomeration of nanoparticles. NH 3 -TPD and H 2 -TPR confirmed that the catalyst had effective acidity and redox capacity that were not affected by alkali metals. In-situ DRIFTs showed that the catalytic reaction predominant mechanism shifted from L−H to E−R mechanism after poisoning. This study provides valuable insights into the development of high-performance Ce-based NH 3 -SCR catalysts with alkali metal resistance.
研究领域:
催化
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环境科学
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
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2018
·
IF 4.439
Zhong-yi Wang,Rui-tang Guo,Xu Shi,Wei-guo Pan,Jian Liu,Xiao Sun,Shuai-wei Liu,Xing-yu Liu,Hao Qin
The Cu/TiO 2 catalysts modified by Sb were compounded through the sol-gel way and put into use for the selective catalytic reduction (SCR) of NOx with NH 3 . Experimental results suggested that CuSb/TiO 2 -0.4 exhibited the excellent NOx conversion and SO 2 tolerance. Subsequently, the relationship between surface physicochemical properties and catalytic performance was also investigated by different characterization methods. From characterizations, the introduction of Sb for Cu/TiO 2 could promote the generation of more Cu 2+ , surface adsorbed oxygen species and surface acid sites on CuSb/TiO 2 -0.4 catalyst. Furthermore, Sb species on CuSb/TiO 2 -0.4 could contribute to the formation of more surface ad-NOx and ad-NH 3 species, which would enhance the NH 3 -SCR process effectively through both the Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanisms.
研究领域:
催化
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环境科学
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材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF CATALYSIS
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2024
·
IF 6.5
Yin Che,Xuezhen Liu,Lifei Liu,Yali Du,Xia An,Xu Wu
Arranging an ammonia oxidation process after the selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) system is an effective way for ensuring the DeNO x efficiency and controlling the slip ammonia. To improve operability and reduce operating costs in ammonia selective catalytic oxidation (NH 3 -SCO), developing feasible and efficient catalysts becomes meaningful. Herein, focusing on the dilemma of Ag/Al 2 O 3 catalysts in NH 3 -SCO applications, Ag/MgAlO x catalysts with different support different crystalline phase structures (5 %Ag/MgAl-LDO and 5 %Ag/MgAl 2 O 4 ) were innovatively synthesized and systematically evaluated application potential in NH 3 -SCO. Results indicated that the introduction of Mg apparently broadened reaction temperature window and catalytic performance of 5 %Ag/MgAl 2 O 4 was higher than 5 %Ag/MgAl-LDO, while the N 2 selectivity was completely opposite. The combination of series characterization and density functional theory (DFT) calculations revealed that 5 %Ag/MgAl 2 O 4 surface has more Ag 0 species with small particle size, which is favorable for ammonia adsorption and activated dehydrogenation to further promote reaction of NO x species, resulting in a higher NH 3 -SCO activity. In contrast, 5 %Ag/MgAl-LDO readily induces oxidized Ag species and Ag 0 is more inclined to be present in large particle sizes, which is more conducive to dissociation of O 2 to produce reactive O species (O*) leading to the peroxidation of ammonia to nitrate and thus, positively affects the improvement of N 2 selectivity. Model catalyst 5 %Ag/MgAl-650 (mixed-phase) was prepared by controlling the roasting conditions and exhibited excellent catalytic performance in NH 3 -SCO with almost 93 % of NH 3 oxidized at 250 °C (N 2 selectivity up to 71 %). This work could afford theoretical support for the optimization and application of catalysts with high performance at low temperatures in selective catalytic oxidation of slip ammonia.
研究领域:
环境科学
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催化材料
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Yuheng Qiao,Zhenzhen Guan,Mengyan Zhang,Gan Chen,Shifeng Zhou,Hailong Liu,Jiang Wu,Ruitang Guo,Weiguo Pan,Fangqin Li,Ping He
In this paper, a series of Fe-based catalysts with Zeolite Socony Mobil-5 (ZSM-5) as supports were synthesized using the sol–gel method to obtain the Fe/ZSM-5, Mn-Fe/ZSM-5, Cu-Fe/ZSM-5 and Cu-Mn-Fe/ZSM-5 catalysts. The synthesized catalysts were examined and characterized via catalytic activity testing, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 adsorption/desorption, scanning electron microscope (SEM), temperature-programmed desorption of NH 3 (NH 3 -TPD), temperature-programmed reduction with H 2 (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that the Cu-Mn-Fe/ZSM-5 catalyst had the best catalytic performance compared with the other catalysts. In addition, Fe/ZSM-5 and Cu-Mn-Fe/ZSM-5 all exhibited excellent stability as well as good tolerance to SO 2 & H 2 O under the experimental conditions. Further characterization results showed that with co-doping of Cu and Mn, the amount of Mn 4+ , Cu + , Fe 3+ and surface chemisorbed oxygen (O β ) on the surface of Fe/ZSM-5 increased, promoting the catalytic performance. The DRIFT studies revealed that the NH 3 -SCR reaction followed both the E-R and L-H mechanism on the surface of the Fe-based ZSM-5 catalyst. The Fe-based ZSM-5 catalyst is a good candidate for NH 3 -SCR both in high reactivity and outstanding stability.
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
Catalysis Science & Technology
·
2020
·Vol. 10
·期 19
·6583-6598
·
IF 5.721
Jialing Chen,Gang Peng,Wei Zheng,Wenbo Zhang,Li Guo,Xiaoqing Wu
A superior Fe-containing MCM-22 zeolite prepared by a one-pot synthesis method (OP-Fe/M22) showed excellent NH3 selective catalytic reduction (NH3-SCR) activity and almost 100% N2 selectivity in a wide temperature window (200–500 °C). To investigate the effects of preparation strategies on the NH3-SCR reaction, other three Fe/MCM-22 zeolites with similar iron content (4.4–4.8 wt%) were prepared by solid-state ion exchange (SSIE-Fe/M22), incipient wetness impregnation (IM-Fe/M22) and mechanical mixing (MM-Fe/M22) methods, respectively. Catalytic results in NH3-SCR demonstrate that OP-Fe/M22 gives significantly higher activity in the whole temperature range (100–550 °C) than the other three post-synthesized catalysts. As revealed by XRD, UV-vis, H2-TPR, NH3-TPD, and Py-IR experiments, OP-Fe/M22 has the highest concentrations of isolated Fe3+ species and acid sites, and the lowest concentration of Fe2O3 nanoparticles among the four catalysts, which ensures its highest activity in the NH3-SCR reaction. Besides, OP-Fe/M22 exhibits the higher activity both in NH3 oxidation and NO oxidation reactions than IM-Fe/M22, indicating the better NO oxidation ability and NH3 storage capacity of OP-Fe/M22 which also facilitates the NH3-SCR process. In contrast with Cu-based MCM-22 zeolite obtained from the incipient wetness impregnation method at similar metal content (5% Cu/M22), OP-Fe/M22 shows comparable activity with 5% Cu/M22 in the low-temperature range (100–300 °C) while obviously higher activity at high temperatures (300–550 °C). Moreover, by removing part of undesired iron oxides in OP-Fe/M22 through mild acid post-treatments, the NH3-SCR activity of OP-Fe/M22 in the medium and high temperature ranges (200–550 °C) can be further improved, suggesting that OP-Fe/M22 is a potential catalyst with highly-efficient NH3-SCR activity in a wide temperature window.
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
危险品化学品经营许可证（带存储）