ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Shanshan Liu,Hao Wang,Ying Wei,Runduo Zhang,Sebastien Royer
ZrO2 supports, with diverse morphologies (hollow sphere, star, rod, mesoporous), were produced using hydrothermal and evaporation-induced self-assembly methods. Zirconia-supported vanadium oxide catalysts were prepared by wet impregnation and used for the low-temperature selective catalytic reduction (SCR) of NO with ammonia. Characterization of catalysts includes N2 physisorption, elementary analysis, X-ray diffraction, high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, temperature-programmed reduction by H2, and temperature-programmed desorption of NH3. Significant differences in terms of activity are measured. 3 wt % V2O5 supported on mesoporous ZrO2 (V/MZ) presents excellent N2 yields (>90%, in the 200–400 °C interval), with a wide operating temperature window (NO conversion > 95%, in the 225–425 °C interval), and less interesting performances were obtained when vanadium oxide is supported over stars, hollow spheres, and rods. Surface characterization showed a content of tetravalent vanadium ion, when supported, decreasing in the order of mesoporous > hollow sphere > star > rod. This order is in perfect agreement with the order of performance of the catalyst in the NH3-SCR reaction. The impact of tetravalent ion’s presence on the surface is confirmed by diffuse reflectance infrared Fourier transform spectroscopy analysis, Brønsted acid sites generated on the surface, and the V4+-OH species involved in the reaction. The production of more important nitrite species over the tetragonal supported vanadium oxide catalyst could be another reason for the excellent NH3-SCR performance displayed by the V/MZ catalyst. When supported over monoclinic zirconia, like vanadium oxide over star-type morphology, the adsorbed NH3 species (NH4+ and coordinated NH3) reacted with NOx adsorption species (nitrate) to form ammonium nitrate. Ammonium nitrate can be decomposed to N2 and N2O (or NO2). Thus, NO conversion curves and N2 yield curves over tetragonal zirconia (MZ) at lower temperature were ahead of those over V/star ZrO2 because of the higher V4+ surface content and more active B acid sites associated with an easy formation of the nitrito intermediate.
研究领域:
催化化学
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环境科学
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材料科学
✓ 已验证
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Yixi Wang,Wenqing Xu,Zhi Liu,Yulong Shan,Wanrong Chen,Xinyu Zhang,Tingyu Zhu
Controlling both CO and NOx pollutants without additional cost is necessary but challenging, especially in industrial flue gas with complex components. Previous studies mainly focused on the effect of O 2 and SO 2 on the CO oxidation side reaction and valence state of Ir species on various catalysts, while neglecting the impact on NO conversion pathway. Herein, we propose an "ineffective reaction pathway" in the presence of O 2 with nitrate as an intermediate according to the results of in situ DRIFTS and DFT. And we also reveal the contribution of SO 2 in inhibiting the adsorption of O 2 and promoting the selective adsorption of NO and CO even at lower injection concentrations, based on the oxidation of SO 2 on Ir(111). This is quite a favorable characteristic for the treatment of industrial flue gas, resolving the long–standing dispute on the involvement of these components in the CO–SCR reaction. Under specific conditions (CO/NO=20, O 2 =5%, SO 2 =200 ppm) at 250 °C, the NOx conversion is as high as 78%. These results will contribute to the development of more efficient catalysts in the future for simultaneously controlling two pollutants (CO and NOx).
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
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Zhipeng Yang,Siru Lu,Tianyu Wu,Hong Yao,Changan Zhou,Chao Wang,Kui Ma,Lei Song,Hairong Yue
Acid sites and redox sites with high thermal stability are crucial for the NH 3 -SCR catalyst for diesel vehicles. The surface acidity of FeTi catalysts is improved by modified with the solid acid of PO 4 3- or WO 3 . The acid-modified FeTi catalysts show superior NH 3 -SCR activity hydrothermal stability with a wide temperature window. The introduction of acid groups not only provides a large number of Brønsted acid sites but also promotes high dispersion of the active species of redox sites due to the formation of the structure P-O-Fe/W-O-Fe. The P-O-Fe/W-O-Fe structure can also improve the redox properties of the FeTi catalysts and inhibit the phase transformation of the TiO 2 support during high-temperature hydrothermal process. The reaction kinetics indicate that the reaction rate is primarily related to the concentration of NO. The mechanistic study indicates that the catalytic reaction is primarily governed by the Eley-Rideal mechanism.
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
ChemCatChem
·
2022
·Vol. 14
·期 17
·e202200476
·
IF 5.497
Shuangxi Li,Weiwei Hu,Ziqiang Xu,Huijun Yu,Tianwei Lan,Lupeng Han,Dengsong Zhang
Graphical Reaction pathway ? More adsorption of NH 3 /NH 4 + species and the higher reactivity with gaseous NO maintain the process of E−R reaction path, leading to a satisfactory SCR activity of K poisoned NbFeVO x /TiO 2 . Whereas the decreased adsorption and reactivity of NH 3 /NH 4 + and NO x restrains the process of L−H reaction path, thus showing inferior SCR activity of K poisoned FeVO 4 /TiO 2 . FeVO 4 -based catalysts with a wide temperature window and high SO 2 tolerance have attracted increasing attention for the selective catalytic reduction of NO x with NH 3 . However, the alkali-resistance of FeVO 4 -based catalysts is still challenging. In this study, the K-resistance of FeVO 4 /TiO 2 was markedly improved via the Nb modification. It was demonstrated that the adsorption and reactivity of NH 3 /NH 4 + and NO x species on K poisoned FeVO 4 /TiO 2 both decreased, which restrained the process of Langmuir-Hinshelwood reaction path. As a comparison, more adsorption of NH 3 /NH 4 + species and the higher reactivity with gaseous NO maintain the process of Eley-Rideal reaction path, leading to a satisifactory SCR activity. This work demonstrated an effective route to improve alkali-resistance via modulating reactivity and reaction path of adsorbed NH 3 /NH 4 + and NO x species over Nb modified vanadate catalysts, which presented a new point for the development of high-performance alkali-resistant SCR catalysts.
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 Environmental Chemical Engineering
·
2023
·
IF 7.7
Liu Yang,Jing Li,Guoqiang Cao,Yiyan Yang,Wen Luo,Zhiqi Zhang,Lizhi Feng,Xinglai Zhang,Baodan Liu
This study reports on the development of highly-efficient Pt/CuO-Fe 2 O 3 /TiO 2 monolithic catalysts for the low-temperature conversion of NO to N 2 via CO-SCR. In this case, ultrathin TiO 2 nanosheet arrays are designed to in situ grow on flexible Ti mesh to provide more spaces/areas for the loading of highly-dispersed Fe 2 O 3 and CuO active components. Furthermore, Pt nanoparticles with an average size of 1.30 nm are effectively decorated on the surface of CuO-Fe 2 O 3 /TiO 2 . The H 2 -TPR and NO-TPD results demonstrate that the excellent synergistic effect between TiO 2 , CuO, Fe 2 O 3 and trace amounts of Pt is conducive to enhance the adsorption of NO and finally promote the CO-SCR. The obtained Pt/CuO-Fe 2 O 3 /TiO 2 catalysts exhibit excellent CO-SCR performance with 100 % NO conversion, and 100 % N 2 selectivity at 250 °C, showing great potential of de-NO x application by using toxic CO as reductant in industry.
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
APPLIED CATALYSIS A-GENERAL
·
2016
·
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
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2024
·Vol. 14
·期 10
·2929-2939
·
IF 4.4
Qian Xu,Zhihong Zheng,Jinjing Luo,Zheng Lai,Jianwen Chen,Jiaxin Shang
Supported MnFeOx catalysts have been prepared using Al2O3 as the substrate and were investigated for NH3-SCR. The 20% MnFe/Al2O3 catalyst removed over 80% of NOx with an N2 selectivity exceeding 90% at temperatures between 80 and 340 °C. The results from the various characterization studies indicated that the increased activity of MnFe/Al2O3 catalysts can be primarily linked to the increased chemisorbed oxygen species and Fe3+ concentrations, greater reducibility, and higher adsorption capacity for NH3. These characteristics are the outcome of the strong interaction, larger specific surface, and abundant acidic sites. Additionally, in situ DRIFTS analysis of the reaction mechanism revealed that the E–R and L–H mechanisms were responsible for the NH3-SCR reaction over the 20% MnFe/Al2O3 catalyst.
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
NEW JOURNAL OF CHEMISTRY
·
2024
·Vol. 48
·期 10
·4335-4345
·
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
·
催化材料
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
·
2024
·
IF 4.1
Yuting Hu,Minghu Zhao,Bo Du,Ting Cheng,Zhaozhong Jiang,Kai Qin,Chengzhu Zhu
A series of M-MnCeO X catalysts using MOF (Metal-organic Framework) were prepared to apply for NH 3 -SCR (Selective Catalytic Reduction) of NO X . The effects of Mn/Ce molar ratio, calcination temperature and its activity including catalytic activity, H 2 O/SO 2 resistance and stability were systematically investigated. The results showed that under the Mn/Ce molar ratio of 1 and calcination temperature of 400 ℃, the catalyst exhibited excellent catalytic activity, H 2 O/SO 2 resistance, and stability. When the concentration of NO was 500 ppm, the gas spatiotemporal velocity (GHSV) was 36,000 h −1 , and the reaction temperature was 100 ℃, the NO conversion efficiency of M-MnCeO X exceeded 90.0 %. Added 200 ppm SO 2 and 3 vol% H 2 O simultaneously, the NO conversion efficiency was close to 80.0 %. By analyzing the physicochemical properties of the catalyst, M-MnCeO X had a large specific surface area, numerous acidic sites, and excellent redox properties. According to density functional theory (DFT), the NH 3 /NO adsorption energy of M-MnCeO X were −2.35 and −2.40 eV, exhibiting lower than a single MOF-derivative, promoting the adsorption of NH 3 or NO. The reaction mechanism on the M-MnCeO X catalyst followed the E-R and L-H mechanisms by In situ DRIFTS.
研究领域:
环境催化
·
材料科学
✓ 已验证
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
·
环境化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Xuesong Liu,Peng Jiang,Yong Chen,Yaoguang Wang,Qiaoling Ding,Zhiming Sui,Hongfeng Chen,Zhongyun Shen,Xiaodong Wu
Two Ce-W-Ti mixed oxide catalysts were prepared by wet impregnation (CeW/Ti-I) and mechanical mixing (Ce/W/Ti-M) methods. CeW/Ti-I catalyst exhibits over 80% NO x conversion and nearly 100% N 2 selectivity at 200–550 °C. The superior catalytic performance is associated with the high dispersion of active CeO 2 and acidic WO 3 on TiO 2 and the synergistic effects among different components. The X-ray Diffraction, Raman spectroscopy, Nitrogen physisorption, X-ray photoelectron spectroscopy, H 2 temperature-programmed reduction, temperature-programmed desorption of ammonia and infrared spectroscopy were performed. It is found that the formation of solid solutions, as well as the high specific surface area, would increase the amounts of Ce 3+ , oxygen vacancies and acid sites in the catalyst. These broaden the operating temperature window of NH 3 -SCR reaction and enhance the N 2 selectivity by facilitating “fast SCR” reaction at low temperatures and inhibiting the unselective oxidation of NH 3 at high temperatures.
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
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
·
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）