APPLIED CATALYSIS B-ENVIRONMENTAL
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2020
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IF 16.683
Shangchao Xiong,Jianjun Chen,Nan Huang,Tao Yan,Yue Peng,Junhua Li
The degradation of catalyst properties, rather than the deposition of NH 4 Cl, was the main reason for the deactivation of the MnCe low-temperature SCR (selective catalytic reduction) catalyst under HCl atmosphere. Cl ions prefer to be located at the oxygen vacancies around Mn cations on the MnCe surface. The adsorbed Cl ions could further promote the formation of oxygen vacancies. Therefore, the active Mn sites on the surface of MnCe would be quickly covered by Cl ions when HCl was present and thus promote the formation of Brønsted acid sites. However, the ionic NH 4 + adsorbed on the Brønsted acid sites of MnCe and MnCe − Cl were not fully utilized in the SCR reaction. Meanwhile, the reactivity of the coordinated NH 3 bonded with Lewis acid sites was significantly restrained by HCl due to the significant inhibition of the redox performance. Overall, HCl could obviously restrain the low-temperature SCR activity of MnCe.
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
Catalysts
·
2019
·Vol. 9
·期 6
·519
·
IF 3.444
Jiaming Shao,Fawei Lin,Yan Li,Hairong Tang,Zhihua Wang,Peixi Liu,Guanyi Chen
NO oxidation was conducted over MnOx-CeO2catalysts, which were synthesized by the co-precipitation method. The calcination temperature and third metal doping were the main considerations. MnCe catalysts calcined at 350 °C and 450 °C attained the highest NO conversion efficiency, compared to 550 °C. XRD results suggested that the higher the calcination temperature, the higher the crystallization degree, which led to a negative effect on catalytic activity. Subsequently, Sn, Fe, Co, Cr, and Cu were separately doped into MnCe composites, but no improvement was observed for these trimetallic catalysts in NO conversion. Nevertheless, MnCeSn, MnCeFe, and MnCeCo still exhibited a desirable NO conversion efficiency, so they were tested under SO2addition together with MnCe catalyst. Among them, MnCeFe exhibited the highest NO conversion after whole poisoning testing. XPS results indicated that Fe could protect Mn and Ce metal oxides from being reduced during SO2poisoning process. Furthermore, in in-situ DRIFTS measurement, part of nitrate species maintained undestroyed on the MnCeFe catalyst surface after SO2poisoning. These characteristics reinforced that Fe dropping would achieve better performance under SO2atmosphere.Keywords:MnOx-CeO2;co-precipitation;NO oxidation;SO2resistance;metal addition
研究领域:
环境科学
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催化化学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2020
·
IF 10.652
Jingheng Gao,Yifei Xiong,Qian Zhang,Yiwen Jiang,Jing Wang,Sibei Zou,Mingli Fu,Junliang Wu,Yun Hu,Daiqi Ye
MnO x -CeO 2 composite catalysts have attracted interest from all over the world as promising catalysts for carbon black oxidation. The contact between carbon black and catalyst, and the surface physicochemical properties of the catalyst, are the main factors in carbon black oxidation, while the contact is a basic one affecting the ignition of the oxidation. In this work, MnO x -CeO 2 catalysts with different geometric morphologies (nanorod and nanoparticle) are prepared to determine the effect of geometric morphology on the contact probability between catalysts and carbon black. Compared with the nanorod catalyst, nanoparticle catalyst is significantly advanced in catalytic activity (T 10 = 314 °C, T 50 = 346 °C, T 90 = 383 °C) and relative contact probability (9.549, compared to the 7.639 of nanorod catalyst, according to the 3D geometric modeling). O 2 -TPD, H 2 -TPR, and In-situ UV Raman experiments reveal that the concentration of surface intrinsic oxygen vacancy of the two catalysts are approximative. The consumption of oxygen vacancy is based on the active sites provided, which is relative to the morphology. The better consumption results in better utilization of intrinsic active oxygen species in nanoparticle sample. This finding proves the correlation between contact probability and carbon black catalytic activity, and witnesses that the consumption efficiency of surface intrinsic oxygen vacancy is an initial factor in carbon black oxidation.
研究领域:
催化化学
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材料科学
✓ 已验证
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2021
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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
APPLIED CATALYSIS B-ENVIRONMENTAL
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2017
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IF 9.446
Hui He,Xueting Lin,Shujun Li,Zeng Wu,Jingheng Gao,Junliang Wu,William Wen,Daiqi Ye,Mingli Fu
Surface species and oxygen vacancies were studied in MnO x (0.4)-CeO 2 toward repeated soot oxidation. MnO x (0.4)-CeO 2 catalysts prepared by the citric acid complex method were repeatedly used in a 10% O 2 /Ar gas flow and showed favorable activity and satisfactory durability toward soot oxidation. X-ray diffraction (XRD), N 2 adsorption/desorption, Electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and in situ visible/UV Raman characterization methods were utilized to investigate the structural features of fresh and reused catalysts. The irreversible conversion of high valence manganese species as well as the reduction of Frenkel-type oxygen vacancies and lattice oxygen could be clearly observed in the reused samples, which were associated with the slight deactivation. Spectators and participators were two existing forms of Frenkel-type oxygen vacancies. It was noteworthy that the participators almost fully regenerated after each reaction cycle, which ensured the ability to activate O latt in repeated soot oxidation process. Therefore, the catalysts maintained favorable activity and satisfactory durability, which was mainly because the relatively stable level of participators.
研究领域:
催化化学
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环境催化
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材料化学
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表面科学
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能源化学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2018
·Vol. 8
·期 6
·1621-1631
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IF 5.365
Yuxi Gao,Xiaodong Wu,Robin Nord,Hanna Härelind,Duan Weng
The sulphur resistance and regeneration strategy of soot oxidation catalysts are critical to the application of catalytic diesel particulate filters (CDPFs). In the present work, Pt/MnOx–CeO2/Al2O3, Pt/Al2O3 and MnOx–CeO2/Al2O3 catalysts were sulphated and regenerated with ammonia. The soot oxidation activity of poisoned Pt/MnOx–CeO2/Al2O3 was recovered completely after 30 min reduction in 500 ppm NH3 at 550 °C. The amount, distribution and structure of sulphates were studied comprehensively for the sulphated and regenerated samples by thermogravimetric analysis (TGA), infrared (IR) spectroscopy, CO chemisorption and transmission electron microscopy (TEM). The NO oxidation of Pt catalysts was found to depend strongly on the particle size distribution, surface exposure and oxidation state of the precious metal. This, as well as the effect of the remaining surface sulphates, helped the regenerated catalysts achieve even higher catalytic activity for soot oxidation.
研究领域:
催化材料
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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
INORGANIC CHEMISTRY COMMUNICATIONS
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2023
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IF 3.8
Xudong Liu,Fengyuan Liu,Junqi Li,Yuanpei Lan,Jian Yang,Arun Murali,Chaoyi Chen,Wei Zhang
To accurately evaluate the phase effects of MnO x in Mn-Ce catalysts towards to low temperature NO x removal performance with NH 3 , MnCO 3 @CeCO 3 OH was synthesized firstly and decomposed to MnO 2 @CeO 2 , Mn 2 O 3 @CeO 2 and Mn 3 O 4 @CeO 2 with similar size and morphology, this will avoid the influence of size and morphology on the experimental results. Experimental results show that the MnO 2 @CeO 2 exhibiting the best NO conversion ratio, which achieved nearly 96.5 % at a low temperature of 150 °C, and the catalytic performance order of MnO x @CeO 2 is determined as: MnO 2 @CeO 2 > Mn 2 O 3 @CeO 2 > Mn 3 O 4 @CeO 2 below 200 °C, and MnO 2 @CeO 2 > Mn 2 O 3 @CeO 2 ≈Mn 3 O 4 @CeO 2 at range of 200 –400 °C. But the N 2 selectivity of Mn 2 O 3 @CeO 2 reaches 96 % at 100 °C which was higher than that of MnO 2 @CeO 2 and Mn 3 O 4 @CeO 2 . Characterizations including BET, XRD, SEM, H 2 -TPR, NH 3 -TPD and FTIR show that MnO 2 @CeO 2 has maximum specific surface area, a stronger redox ability, and more surface acid sites.
研究领域:
催化材料
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环境科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMISTRY-A EUROPEAN JOURNAL
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2025
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IF 3.7
Zhixian Wang,Yuntao Hu,Zhigang Zhang,Bin Wang,Gengxiu Zheng,Huaiqing Zhao
The development of synthetic methods for N-heterocyclic compounds have garnered considerable attention due to their significance in diverse chemical processes. Among various synthesis methods, the direct oxidative dehydrogenation of saturated substances to N-heteroaromatics is a simple and efficient method. This study utilized the pyrolysis of Mn/Ce-BTC MOFs precursor to prepare MnO X -CeO 2 composites as a heterogeneous catalyst for the aerobic oxidative dehydrogenation of N-heterocycles. The MnO X -CeO 2 composites were analyzed with various characterization techniques including XRD, SEM, TEM, BET, XPS, ICP-OES and Raman spectroscopy. The detailed findings from experiments indicate that the catalytic activity of the composites has been significantly improved due to the synergistic effect of MnO X -CeO 2 and the abundant oxygen vacancies on the surface of the catalyst. And the related mechanism experiments reveal that reactive oxygen species (ROS) are involved in this catalytic system. Furthermore, MnO X -CeO 2 composites retain excellent catalytic performance even after ten recycles. Graphical The synthesized bimetallic oxides MnO X -CeO 2 by the pyrolysis of Mn/Ce-BTC MOFs have been employed as a heterogenous catalyst for the oxidative dehydrogenation of N-heterocycles to N-heteroaromatics with oxygen as the solo oxidant.
研究领域:
催化化学
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材料化学
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有机合成
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无机化学
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环境化学
✓ 已验证
DOI
PubMed
高影响因子
CATALYSIS TODAY
·
2014
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IF 3.309
Yuxi Gao,Xiaodong Wu,Shuang Liu,Duan Weng,Hongwei Zhang,Rui Ran
MnO x –CeO 2 mixed oxides were synthesized using a sol–gel method and the barium-loaded catalyst was prepared by a wet impregnation. Both catalysts were hydrothermally aged at 800 °C for 10 h. The fresh and aged catalysts were characterized by X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), high-resolution transmission electron microscopy (HRTEM), H 2 temperature-programmed reduction (H 2 -TPR), NO temperature-programmed oxidation (NO-TPO) and soot temperature-programmed oxidation (soot-TPO). Compared with MnO x –CeO 2 , the Ba-modified mixed oxides show a much higher hydrothermal stability. Barium exists in the form of orthorhombic carbonate and cubic nitrate on the fresh sample. BaMnO 3 nanoparticles are identified to form at the interface of CeO 2 crystallites upon the hydrothermal ageing. The formation of the perovskites prohibits the sintering of ceria significantly, and consequently maintains the redox property of the aged mixed oxides to a great degree. Additionally, the nanoscaled perovskites themselves also contribute to the catalytic activity of the aged oxides catalyst.
研究领域:
催化材料
·
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）