RSC Advances
·
2018
·Vol. 8
·期 11
·6110-6119
·
IF 2.936
Chengkai Pang,Yuqun Zhuo,Qiyu Weng,Zhenwu Zhu
The activity and hydrothermal stability of Cu/SAPO and xMn–2Cu/SAPO for low-temperature selective catalytic reduction of NOx with ammonia were investigated. An ion-exchanged method was employed to synthesize xMn–2Cu/SAPO, which was characterized by N2 adsorption, ICP-AES, X-ray diffraction (XRD), NH3-temperature programmed desorption (NH3-TPD), NO oxidation, X-ray photoelectron spectrum (XPS), UV-vis, H2-temperature programmed reduction (H2-TPR) and diffuse reflectance infrared Fourier transform spectra (DRIFTS). 2Mn–2Cu/SAPO and 4Mn–2Cu/SAPO showed the best SCR activity, in that at 150 °C NO conversion reached 76% and N2 selectivity was above 95% for the samples. NO oxidation results showed that the 2Mn–2Cu/SAPO had the best NO oxidation activity and the BET surface area decreased as manganese loading increased. XRD results showed that the metal species was well dispersed. NH3-TPD showed that the acid sites have no significant influence on the SCR activity of xMn–2Cu/SAPO. H2-TPR patterns showed good redox capacity for xMn–2Cu/SAPO. UV-vis and H2-TPR showed that the ratio of Mn4+ to Mn3+ increased as manganese loading increased. XPS spectra showed a significant amount of Mn3+ and Mn4+ species on the surface and addition of manganese increased the ratio of Cu2+. The promotion effect of manganese to 2Cu/SAPO comes from the generation of Mn3+ and Mn4+ species. Deduced from the DRIFTS spectra, the Elay–Rideal mechanism was effective on 4Mn–2Cu/SAPO.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
ChemCatChem
·
2018
·Vol. 10
·期 11
·2481-2487
·
IF 4.674
Yani Zhang,Yue Peng,Chizhong Wang,Kezhi Li,Shuai Liu,Xiansheng Li,Jianjun Chen,Junhua Li
Graphical Change for copper : Copper ion exchanged SAPO-47 zeolite catalysts are synthesized and used for the selective catalytic reduction (SCR) of NO x with ammonia, for which they exert high activity. The structure–activity relationship is explored. Copper-exchanged H-SAPO-47 zeolites were synthesized by an aqueous solution ion exchange method and applied in the selective catalytic reduction of NO with NH 3 (SCR). The microporous chabazite (CHA) structure of the catalysts was characterized and confirmed using synchrotron X-ray diffraction and nitrogen adsorption–desorption experiments. The synthesized Cu x -SAPO-47 catalysts exhibited excellent SCR activity and nearly 100 % N 2 selectivity in a wide temperature range. The Cu 0.1 -SAPO-47 sample exhibited higher activity than the other samples below 250 °C. The weak Lewis acid sites originating from the introduction of Cu 2+ were more active than the Brønsted acid sites of the zeolites framework at low temperature. Two types of isolated Cu 2+ species with different coordination surroundings were found, namely, Cu 2+ cations bonded with the six-membered rings and those bonded in the CHA cages. The former species exhibited good stability and activity at high temperature, whereas the latter ones were more active at low temperature. The Cu 0.1 -SAPO-47 catalyst provided a considerable amount of isolated Cu 2+ bonded in the CHA cages. These results indicated that active Lewis acid sites and isolated Cu 2+ species are responsible for their excellent SCR activity.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2017
·Vol. 24
·期 8
·7499-7510
·
IF 2.741
Yu Chenglong,Chen Feng,Dong Lifu,Liu Xiaoqing,Huang Bichun,Wang Xinnan,Zhong Shengbang
Manganese-rich MnSAPO-34 molecular sieves were prepared by one-pot synthesis method for NO
x
abatement using the ammonia-selective catalytic reduction (NH 3 -SCR) technology and characterized using ICP, BET, XRD, FE-SEM, H 2 -TPR, NH 3 -TPD, XPS, and DR UV-Vis analyses. The experimental results indicate that the Mn content and chemical state, as well as the surface acidity, of the MnSAPO-34 molecular sieves significantly enhance their DeNO
x
efficiency at low temperatures (ca. 200–300 °C). The manganese-rich MnSAPO-34 was synthesized using a combination of triethylamine and diisopropylamine as the structural directing agents and high Mn loading ( n (MnO)/ n (P 2 O 5 ) = 0.4). The resulting catalyst exhibits the highest activity among all of the samples with a NO
x
conversion value of nearly 95% and a N 2 selectivity that is higher than 90% at 220–400 °C. In addition, this catalyst presents higher NO
x
conversion than the conventional V 2 O 5 -WO 3 /TiO 2 catalysts and other SAPO-based catalysts below 300 °C. Furthermore, the analytical results indicate that the manganese species in the catalyst are mainly in the form of a framework Mn(IV), which could play a significant role in the NH 3 -SCR process as the specific active species. The results suggest that controlling the types and content of the organic amine templates and variations in the surface acidity of the catalysts may significantly enhance the SCR activity at lower temperatures.
研究领域:
环境催化
·
材料化学
·
工业催化
·
大气污染控制
·
无机多孔材料
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2018
·
IF 6.735
Yarong Bai,Junping Dong,Yaqin Hou,Yaoping Guo,Yongjin Liu,Yulin Li,Xiaojin Han,Zhanggen Huang
Herein, a series of Co 3 O 4 nanoparticles inlaid in porous carbon (CoO x @PC-T) were successfully prepared via first pyrolysis of ZIF-67 in argon atmosphere at different temperature and then oxidized in 5% O 2 /Ar mixed gas. The as-made samples were employed as catalysts for selective catalytic reduction of NO x with NH 3 at low temperature (100 °C–200 °C). The effect of pyrolysis temperature on the microstructure, textural properties, and chemical properties of CoO x @PC-T were characterized by TG-MS, BET, XRD, SEM, TEM, H 2 -TPR and XPS in detail. Results show that the pyrolysis temperature has a significant effect on the carbonization degree of carbon in ZIF-67, and which in turn affects the exposure and oxidization of cobalt nanoparticles on the catalyst surface. Experiments results show that CoO x @PC-800 display the highest NO x conversion ratio, which is attributed to its higher ratio of Co 3+ /Co 2+ and large specific surface area. Moreover, the stability, H 2 O and SO 2 resistance of CoO x @PC-800 were also studied.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2016
·Vol. 6
·期 24
·8516-8524
·
IF 5.287
Lei Huang,Kaiwen Zha,Supawadee Namuangruk,Anchalee Junkaew,Xin Zhao,Hongrui Li,Liyi Shi,Dengsong Zhang
Surface engineering of TiO2 is significant in the SCR reaction and worth studying. In a previous study, we found that TiO2 nanosheets (TiO2-NS) with the (001) plane exhibited a much better SCR performance than TiO2 nanoparticles (TiO2-NP) with the (101) plane. In this work, in situ DRIFTS and DFT calculations were applied to address the promotional effect of the (001) plane of TiO2-NS in the SCR reaction. The behavior of adsorption and desorption of NOx and NH3 on the two surfaces was studied. It was found that NH3 adsorbed on both TiO2-NS and TiO2-NP was in the form of NH3(g) on the Lewis acid sites. NOx on TiO2-NP were mainly trans-(NO)2 and N2O4 which were non-reactive. Differently, NO on TiO2-NS was mainly in the form of NO2 which was probably due to the high energy and abundant active oxygen species of the (001) facet. The formed NO2 could trigger the subsequent ‘fast SCR’ reaction thereafter promoting the activity. Therefore, TiO2-NS with more (001) facets had better SCR activity than TiO2-NP with the exposed (101) facet.
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
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2014
·
IF 6.007
Jun Yu,Zhichun Si,Lei Chen,Xiaodong Wu,Duan Weng
A zirconium phosphate @ Ce 0.75 Zr 0.25 O 2 (ZP/CZ) catalyst was synthesized by impregnating zirconium phosphates on Ce 0.75 Zr 0.25 O 2 microspheres. Catalysts with different structures were also synthesized by various methods to illustrate the structure advantage of ZP/CZ catalyst in selective catalytic reduction of NO x by ammonia (NH 3 -SCR). The catalysts were characterized by scanning electron microscope (SEM), X-ray diffraction (XRD), BET surface area, Infrared (IR) spectra, Ultraviolet-visible (UV–vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 -temperature programmed reduction (TPR) and diffuse reflectance infrared Fourier transformed spectra (DRIFTS) of NH 3 /NO x adsorption. ZP/CZ catalyst presents excellent catalytic activity at 250–450 °C with a good N 2 selectivity under high space velocity of 300,000 h −1 . Firstly, the zirconium phosphate provides adsorption sites for ammonia on the surface of the catalyst and the cerium sites in the core act as the redox sites for NO oxidation. The pre-combination of zirconium and phosphate can reduce the strong interactions between phosphates and cerium ions. Therefore, the mobility of surface lattice oxygen on Ce 0.75 Zr 0.25 O 2 catalyst is retained, which is essential to obtain a catalyst with high NH 3 -SCR activity at low temperatures. Moreover, NH 4 NO 3 has proved to be an important intermediate for the NH 3 -SCR reaction on the surface of ceria based catalysts. The ZP/CZ catalyst preserves plenty of oxygen vacancies, facilitating the Ce 4+ → Ce 3+ redox circles and therefore promotes the nitrites/nitrates formation and desorption on catalyst. Two distinct adsorption sites for NH 3 and NO x result in a close contact between ads-NH 3 /NH 4 + and ads-NO 3 − /NO 2 − species on ZP/CZ catalyst, which can react with NO rapidly with the participation of active surface lattice oxygen.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2021
·
IF 8.128
Yu Zhang,Shan Yang,Xiaoyue Zhu,Xiaolin Xu,Fang Huang,Zhongnian Yang,Chuanzhi Sun
Hematite (α - Fe 2 O 3 ) is a promising candidate for NH 3 selective catalytic reduction (NH 3 -SCR) of NO x due to its good sulfur resistance. However, the activity of pure α - Fe 2 O 3 is very low. In this work, α - Fe 2 O 3 obtained excellent N 2 selectivity and medium–high temperature activity via a simple surface sulfation method. The α - Fe 2 O 3 -350 (sulfated at 350 °C) sample showed an NO conversion rate of ~ 100% in the range of 275–350 °C and exhibited excellent H 2 O and SO 2 resistance ability at 300 °C. Furthermore, pure α-Fe 2 O 3 was used as a model catalyst to fully uncover the effect of sulfation on FeO x -based catalysts in NH 3 -SCR reactions. Structural characterization indicated that the degree of surface sulfation of the catalyst would be deepened with increasing temperature, and the states of sulfate species on α - Fe 2 O 3 changed from surface sulfates to bulk-like sulfates. Although sulfation treatment reduced the redox properties of α - Fe 2 O 3 , it significantly increased its surface acidity and thus the activity. Excessive bulk-like sulfates induced a decrease in activity. Sulfation inhibited the adsorption of NO x on the α - Fe 2 O 3 catalyst surface and reduced the thermal stability of nitrates at medium–high temperature. Thus, the Langmuir-Hinshelwood (L-H) mechanism was inhibited, and the reaction mainly followed the Eley-Rideal (E-R) mechanism.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
LANGMUIR
·
2025
·
IF 3.9
Jin Yuan,Jinxing Mi,Weitao Zhao,Ke Zheng,Shaoqi Zhou,Jianjun Chen
Although ceria-based catalysts have been proven to be a promising alternative to conventional vanadyl catalysts for the selective catalytic reduction of NOx with NH3 (NH3–SCR), whether the interaction between tungsten (W) and CeO2 could be well established for enhancing SCR performance is still unclear. Herein, W/CeO2 catalysts with different CeO2 morphologies for SCR are fully investigated. Systematic characterization results confirmed that the crystalline WO3 phase was formed on W-loaded CeO2 nanocubes, nanospindles, and nanospheres. Intriguingly, the W/CeO2 nanorods exhibited exclusively polymeric tungstate species. This divergence originates from the distinct W-CeO2 interaction mediated by preferentially exposed {110} lattice planes, endowing the nanorod catalyst with stronger reducibility, more surface-active oxygen species, and acid sites. Consequently, the NH3–SCR activity followed the order W/CeO2 nanorods > W/CeO2 nanospindles > W/CeO2 nanocubes > W/CeO2 nanospheres. This work reveals the significant role of the CeO2 morphology in the dispersion and interaction of W species, which directly influences the NH3–SCR performance. The insight offers a valuable opportunity for the design of a more efficient SCR catalyst.
研究领域:
化学工程
·
催化科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Catalysts
·
2022
·Vol. 12
·期 11
·1430
·
IF 4.501
Yang Gao,Li Cao,Xiaodong Wu,Xu Zhang,Ziran Ma,Rui Ran,Zhichun Si,Duan Weng,Baodong Wang
CeNbTi catalyst was poisoned in different sulfur poisoning atmospheres at 300 °C for 6 h and then was evaluated for selective catalytic reduction (SCR) of NOxwith NH3. The catalyst deactivation upon SO2exposure was effectively inhibited in the presence of NH3. Temperature-programmed decomposition (TPD) analyses were applied to identify deposit species on the poisoned catalysts by comparison with several groups of reference samples. Diffuses reflectance infrared Fourier transform spectroscopy (DRIFTS) over CeNbTi catalysts with different poisoning pretreatments and gas purging sequences were designed to investigate the roles of NH3in the removal of surface sulfites and sulfates. More ammonium sulfates including ammonium bisulfate and ammonium cerium sulfate were generated instead of inert cerium sulfate in these conditions. The mechanisms about the formation and transformation of surface deposits upon sulfur poisoning w/wo NH3were explored, which provided a basis for developing Ce-based mixed oxides as SCR catalysts for stationary sources.Keywords:ceria;SCR;sulfur;NH3;TPD;DRIFTS;deposit
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
Materials
·
2024
·Vol. 17
·期 6
·1440
·
IF 3.1
Yarong Bai,Chuhan Miao,Weilong Ouyang,Lang Wang,Haiqiang Wang,Zhongbiao Wu
Barium and iridium supported on Zeolite Socony Mobil-5 (ZSM-5) are efficient catalysts for the selective catalytic reduction of nitric oxide by carbon monoxide (CO-SCR), with enhanced cyclic stability. The introduction of Ba hindered the oxidation of metallic Ir active species and enabled Ir to maintain an active metallic state, thereby preventing a decrease in catalytic activity in the CO-SCR reaction. Moreover, the Ba modification increased the NO adsorption of the catalyst, further improving the catalytic activity. Owing to the better anti-oxidation ability of Ir0in IrBa0.2/ZSM-5(27) than in Ir/ZSM-5(27), IrBa0.2/ZSM-5(27) showed better stability than Ir/ZSM-5(27). Considering that all samples in the present study were tested to simulate actual flue gases (such as sintering flue gas and coke oven flue gas), NH3was introduced into the reaction system to serve as an extra reductant for NOx. The NOxconversion to N2(77.1%) was substantially improved using the NH3-CO-SCR system. The proposed catalysts and reaction systems are promising alternatives for treating flue gas, which contains considerable amounts of NOxand CO in oxygen-enriched environments.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
PubMed
高影响因子
FUEL
·
2024
·
IF 6.7
Wei Fu,Muhammad Kashif,Chen Cai,Jiayin Chen,Hao Zhou,Bingtao Zhao,Philippe M. Heynderickx,Yaxin Su
The hydrothermal technique was applied to prepare a new metal–organic framework, MIL-100(Fe), which was modified by ultrasonic impregnation with different wt % of copper. The results showed that the NO x conversion over 2.3Cu-MIL-100(Fe) was 100 % at 275 °C and maintained at ≥ 85 %, with N 2 selectivity ≥ 90 % in the temperature range of 275–400 °C and high SO 2 resistance. An increase in the Cu content up to 2.3 wt% showed the highest surface area (1206 m 2 /g) observed in N 2 adsorption–desorption. The results show that the introduction of Cu increased the oxygen vacancies on the catalyst surface. Electron transfer and a synergistic effect were observed between Cu and Fe. The shift of the reduction peaks to lower temperatures after the addition of Cu confirmed that Cu improved the reducibility of the catalysts. The 2.3Cu-MIL-100(Fe) exhibited the highest Lewis content (44.97 μmol/g), which functions as an active site for the selective catalytic reduction (SCR) reaction. By precisely controlling the acid-base properties of the catalyst, the specificity for the desired products can be increased in complicated reaction systems, especially in hydrocarbon-SCR technology.
研究领域:
材料科学
·
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
Journal of Environmental Chemical Engineering
·
2019
·
IF 0
Limei Cao,Qian Wang,Ji Yang
A novel ultrafine Pt/Beta catalyst supported on carbon paper was prepared and applied to selective catalytic reduction of NO x by H 2 at a low temperature below 90 °C. Here, 0.8 wt.% Pt/Beta reached approximately 100 % NO conversion at 90 °C under oxygen-rich conditions (1000 ppm NO, 1 % H 2 , and 4 % O 2 ). The influence of the dispersion and particle size of Pt on the catalytic performance was investigated using Polyvinylpyrrolidone (PVP) as a structure directing agent to regulate the Pt particles. The feeding amount of PVP significantly influenced the catalytic activity of the catalysts. When the feeding amount was less than 50 mg, the Pt particle size was smaller, and the dispersion was higher, providing a higher NO conversion. However, when the feeding amount exceeded 50 mg, the dispersion no longer increased, and the activity slightly decreased. N 2 physisorption (BET) confirmed that excessive PVP decreased the specific surface area, which suppressed the catalytic activity of Pt/Beta. Moreover, the NO conversion efficiency was dependent on the dispersion and particle size of Pt and was minimally affected by the surface area of the catalysts. The Pt/Beta catalyst system was deactivated, and an irreversible poisoning phenomenon for SO 2 was observed. Zr, Ce, and V were introduced into the catalyst system as metal auxiliaries . The Ce-modified Pt-Ce/Beta catalyst prepared in this study showed resistance to SO 2 .
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
危险品化学品经营许可证（带存储）