Journal of Environmental Chemical Engineering
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2021
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IF 5.909
Xuan Bie,Kai Wu,Kunling Jiao,Kun Zhao,Xiangyang Chen,Suangchen Ma
Generally, using transition metal oxides as catalysts is the typical method for ammonia-selective catalytic reduction (NH 3 -SCR) under the medium temperature zone (150–400 °C). The controllable structure and uniformly distributed active sites of (Fe&Mn)AlOx-based catalysts via a facilely operative and green prepared method were employed for high NO catalyzed efficiency and selectivity . Among them, the Mn 1.2 Al 0.8 O x sample exhibited excellent low-temperature activity, and Fe 1.2 Al 0.8 O x exhibited excellent N 2 selectivity, which could be ascribed to the unique surface feature (more redox sites on Mn 1.2 Al 0.8 O x and more acid sites on Fe 1.2 Al 0.8 O x ). This creative work has directly demonstrated the importance of coordination between the adsorption of species and electron transportation that emerged on active sites. Meanwhile, the reaction process has been clearly presented in in-situ DRIFTS, declaring the synergetic mechanism (Eley-Rideal mechanism and Langmuir-Hinshelwood mechanism) in the systems. The Eley-Rideal mechanism could be the dominant one due to its rapid reaction rate. The predictable insights are beneficial for profoundly understanding the dual-sites synergetic interaction for controllable conversion rate and high selectivity in the medium temperature SCR process.
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
JOURNAL OF HAZARDOUS MATERIALS
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2020
·
IF 9.038
Xiaoming Zhou,Zhuoyuan Chen,Zhiyong Guo,Haiping Yang,Jingai Shao,Xiong Zhang,Shihong Zhang
A series of dual metal incorporated CuCex-SAPO-34(x = 0–0.04) samples were synthesized using one-pot hydrothermal method with diethylamine as organic structure-directing agent for selective catalytic reduction of NO x by NH 3 . The catalytic properties were elucidated in detail with physicochemical properties being analyzed using various instruments. All the catalysts exhibited typical SAPO-34 crystal structures with high specific surface areas. With the dual-metal incorporation, the surface acidity and amount of isolated Cu 2+ , which may be active sites for NH 3 -SCR, were significantly enhanced. However, excessive Ce restrained the formation of isolated Cu 2+ due to its occupation of cationic sites. Therefore, the 0.05CuCe0.02-SAPO-34 exhibited high NO conversion (≥80%) at 168°C-500°C. Furthermore, the NH 3 -SCR mechanism over different catalysts was investigated in-situ DRIFTS experiments. For the 0.05Cu-SAPO-34, the adsorbed NH 3 species react with gaseous NO and following the E-R mechanism throughout the reaction temperature range. Meanwhile, adsorbed NO 2 was detected and reacted with the adsorbed NH 3 species according to the L-H mechanism in low-temperature region. In contrast, the NH 3 -SCR reaction over the 0.05CuCe0.02-SAPO-34 primarily followed the E-R mechanism throughout the temperature range. The L-H mechanism was cut off due to the loss of the adsorption ability of nitrous species at high temperatures., resulting in NO conversion decreasing.
研究领域:
环境科学
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材料科学
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产品关联
DOI
PubMed
高影响因子
CHEMICAL ENGINEERING JOURNAL
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2019
·
IF 8.355
Hanzi Liu,Changfu You,Haiming Wang
Transient in-situ IR spectroscopy was performed to analyze the molecular behavior of selective catalytic reduction of NO with NH 3 on V 2 O 5 -WO 3 /TiO 2 catalyst. During NH 3 adsorption, an unexpected growth in the intensity of Lewis acid sites was observed due to the hydrogen migration, which was verified by the DFT calculation and the existence of intermediate species. The comparison between the isolated atmosphere experiments and the simultaneous exposure of NH 3 -NO-O 2 on catalytic monolayer demonstrated that: (i) there exists a pathway for Lewis to Brønsted acid sites transformation at T > 300 °C, (ii) the rate determining step of the SCR cycle involves in the re-oxidation of acid sites by O 2 at 200–300 °C. Generally, the Lewis acids are crucial at high temperatures, while Brønsted acids dominate the overall reaction at lower temperatures. Based on the experimental data and the DFT calculation, a mechanism for ammonia adsorption, acidity conversion and re-oxidation for the redox loop of the de-NOx reaction was proposed. The findings shed light on the understanding of relative strength of NO reduction and acid re-oxidation at different temperatures.
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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2020
·
IF 10.652
Yiqing Zeng,Yanan Wang,Plaifa Hongmanorom,Zhigang Wang,Shule Zhang,Jiatang Chen,Qin Zhong,Sibudjing Kawi
Highly-efficient CeO 2 -TiO 2 -based catalyst is an attractive alternative to traditional V 2 O 5 -based catalysts for selective catalytic reduction of NO x by NH 3 (NH 3 -SCR). Herein, we construct an efficient and stable P-doped CeO 2 /TiO 2 ( y CeTi-P x ) catalyst by dispersing CeO 2 on strongly acidic and highly stable mesoporous P-doped TiO 2 (Ti-P x ). The characteristic structure of Ti-P x causes highly dispersed CeO 2 , strong active component-support interaction, and abundant surface active oxygen and acid sites on CeTi-P catalyst. Therefore, y CeTi-P x catalyst exhibits much higher catalytic activity than y CeTi catalyst at temperature of 200–450 °C. The y CeTi-P x catalysts show high activity in the presence of H 2 O and strong resistance to H 2 O + SO 2 at medium-high temperature, implying that they have great industrial application prospects. Different P/Ti ratio and CeO 2 loading content were investigated. Excessive P doping can block the Ce 4+ /Ce 3+ redox couple, and suppress redox sites on y CeTi-P x catalyst. Additionally, increasing CeO 2 content can reduce the NH 3 capacity of y CeTi-P x catalyst. By controlling the P/Ti ratio and CeO 2 loading content, surface acid sites and redox sites on y CeTi-P x catalyst can be balanced to obtain the best catalytic activity. This work demonstrates a feasible method in adjusting acid sites and redox sites on CeTi catalyst, which ultimately contributes to the new design of CeO 2 -TiO 2 -based 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
Chemistry-An Asian Journal
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2018
·Vol. 14
·期 3
·416-421
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IF 3.692
Qian Wang,Wei Sun,Tianying Xie,Limei Cao,Ji Yang
Graphical Carbon-coated catalysts : Octahedral Pt/ZrO 2 @C, prepared by direct carbonization of the precursor UiO-66-NH 2 (a zirconium-based metal–organic framework), exhibits improved catalytic activity for selective catalytic reduction with H 2 at ambient temperature, compared with that of other platinum-based catalysts with porous materials as supports (see figure). Selective catalytic reduction (SCR) of NO x with H 2 as a reductant is the most promising denitration technology at low temperature. Achieving the conversion of NO x into N 2 at ambient temperature not only prolongs the service life of the catalyst, but also provides more freedom for the arrangement of denitration units throughout the flue gas treatment equipment. However, the development of highly efficient, stable, and environmentally benign supported platinum-based catalysts for H 2 -SCR at ambient temperature is still a major challenge. Herein, a 0.5 wt % Pt/ZrO 2 @C catalyst, which was composed of carbon-coated octahedral ZrO 2 with highly dispersed Pt particles, was prepared by using a new stabilization strategy based on UiO-66-NH 2 (a zirconium metal–organic framework) as a template. The catalytic performance of this Pt/ZrO 2 @C in H 2 -SCR was tested and confirmed to achieve near 100 % NO x conversion at 90 °C. Also, 70 % N 2 selectivity of the catalyst was achieved. The morphology, structure, and porous properties of the as-synthesized nanocomposites were characterized by using data obtained from field-emission SEM, TEM, XRD, Raman spectroscopy, thermogravimetric analysis, X-ray photoelectron spectroscopy, and N 2 adsorption–desorption isotherms. The results show that residual carbon formed by pyrolysis treatment is coated on octahedral ZrO 2 , and effectively prevents the agglomeration of platinum particles on the surface.
研究领域:
化学工程
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材料科学
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环境科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF RARE EARTHS
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2020
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IF 3.104
Youchun Pan,Qijie Jin,Bingxu Lu,Yan Ding,Xin Xu,Yuesong Shen,Yanwei Zeng
MnCeO x /TiO 2 has been widely used in selective catalytic reduction (SCR) of NO x at low temperature. However, it is often poisoned in the presence of water vapor and sulfur dioxide . In this work, the promotion mechanism of Ba modification was investigated. Results show that the doped BaO reacts with CeO 2 and forms BaCeO 3 . This unique perovskite structure of BaCeO 3 significantly enhances NO oxidation and NH 3 activation of MnCeO x /TiO 2 catalyst so that the NO conversion and the resistances to SO 2 improve. It is found that Ba species obviously promotes the NO adsorption ability and improve the redox properties of MnCeO x /TiO 2 catalyst. While the acid properties of the catalyst are inhibited by Ba modification and among which Lewis acid sites are dominant for both MnCeO x /TiO 2 and MnCe(Ba)O x /TiO 2 catalysts. Furthermore, in situ DRIFT experiments reveal that the NO reduction upon MnCeO x /TiO 2 and MnCe(Ba)O x /TiO 2 catalysts follows both E-R and L-H mechanisms, in which L-H is preferred. Ba species enhances the formation of active nitrate species, which accelerates the NO reduction through L-H mechanism. It is interesting that although Ba species weakens the NH 3 adsorption, it induces the ammonia conversion to coordination ammonia, which in turn accelerates the catalytic reaction .
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
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2021
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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
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2019
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IF 6.361
Xiaoqiang Wang,Yue Liu,Weiyuan Yao,Zhongbiao Wu
In this paper, a series of Sb modified CeZr 2 O x mixed oxides (Sb y CZ) were synthesized by citrate method for the selective catalytic reduction of NO with ammonia (NH 3 -SCR). Experimental results exhibited that the Sb addition could bring a great improvement of SCR activity at 200–360 °C owing to the enhancement in surface area , redox ability and surface acidity . More importantly, the sulfur tolerance of the catalyst with proper Sb loading contents was dramatically improved. For instance, above 85% deNO x efficiency was retained over Sb 0.5 CZ catalyst after 24 h reaction in the presence of 100 ppm SO 2 and 5 vol.% H 2 O. As for pure CeZr 2 O x and the catalysts with low Sb loading contents, the serious accumulation of ammonium sulfates resulted in the deactivation after SO 2 exposure. However, with excessive Sb addition, more labile oxygen readily reacted with SO 2 and the redox cycle was then disrupted, leading to the decrease of SCR activity. With an appropriate Sb loading contents, the sulfate species preferentially formed around Sb cations could restrain the further consumption of oxygen species in Ce-O-Ce or Ce-O-Zr mode by SO 2 via a space confinement effect. Thus, a certain amount of labile oxygen was preserved to drive the SCR reaction, thereby enhancing the sulfur tolerance of the catalyst.
研究领域:
催化
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环境化学
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材料科学
✓ 已验证
DOI
高影响因子
Catalysts
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2022
·Vol. 12
·期 5
·549
·
IF 4.501
Li Wang,Junbo Wang,Heping Cheng,Xiangxiang Zhou,Zhen Ma
A series of Ce1−xFexVO4(x = 0, 0.25, 0.50, 0.75, 1) catalysts prepared by modified hydrothermal synthesis were used for selective catalytic reduction (SCR) of NOxwith NH3. Among them, Ce0.5Fe0.5VO4showed the highest catalytic activity. The catalysts were characterized by X-ray diffraction (XRD), N2adsorption–desorption, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray spectroscopy (EDX), X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction using H2(H2-TPR), and temperature-programmed desorption of NH3(NH3-TPD). The results indicated the formation of Ce-Fe-V-O solid solutions. The average oxidation states (AOS) of Ce, Fe, V, and O atoms changed obviously with the incorporation of Fe3+into CeVO4, and the acidity of Ce0.5Fe0.5VO4differs from that of CeVO4and FeVO4. The presence of more acid sites and a sharp increase in active oxygen species in Ce0.5Fe0.5VO4effectively improved the selective catalytic reduction (SCR) activity.Keywords:selective catalytic reduction;nitrogen oxides;cerium vanadate;iron vanadate;cerium-iron vanadate
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
Applied Sciences-Basel
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2018
·Vol. 8
·期 1
·95
·
IF 1.689
Chengzhi Wang,Cheng Zhang,Yonggang Zhao,Xin Yan,Peng Cao
Honeycomb cordierite-based Mn–Ce/Al2O3catalysts were prepared by the impregnation method and used for low-temperature selective catalytic reduction (SCR) of NOxwith NH3, with and without SO2and/or H2O in a homemade fixed-bed tubular reactor. The catalyst reached nearly 80% NOxconversion at 100 °C in the absence of SO2. However, SO2reduces the catalytic activity (80% to 72%) of the honeycomb cordierite-based Mn–Ce/Al2O3catalysts under identical conditions. This finding demonstrated that the catalyst exhibited high activity at low temperature and excellent SO2resistance in the presence of 50 ppm SO2. The fresh and sulfated honeycomb cordierite-based Mn–Ce/Al2O3catalysts were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), N2adsorption–desorption, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), thermogravimetry and differential thermal analysis (TG-DTA), and Fourier transform infrared (FT-IR) spectroscopy. Characterization results indicated that the deactivation by SO2was primarily the result of the deposition of ammonium hydrogen sulfate and sulfated CeO2on the catalyst surface during the SCR process. The formed sulfates depressed the catalytic activity via the blocking of pores and the occupation of active sites. Additionally, the competitive adsorption between SO2and NH3always decreased the catalytic activity.Keywords:Mn–Ce/Al2O3catalyst;low temperature selective catalytic reduction;honeycomb cordierite;SO2resistance
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
JOURNAL OF RARE EARTHS
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2021
·
IF 3.712
Yiqing Zeng,Shule Zhang
Revealing the active species of the catalyst is conducive to the design of more efficient catalyst. Herein, we tried to demonstrate the roles of amorphous and crystalline structures on CePO 4 catalyst during selective catalytic reduction (SCR) of NO x by NH 3 . Higher calcination temperature promotes the transfer of amorphous structure to crystalline structure on the surface of CePO 4 . Both amorphous and crystalline CePO 4 species on CePO- X samples can provide acid sites for NH 3 adsorption, but the former can provide more acid sites. The superior redox property of surface amorphous CePO 4 species contributes to its high NH 3 -SCR activity at low temperature, but it also leads to the decrease of high temperature (>350 °C) NH 3 -SCR activity due to the oxidation of NH 3 . In contrast, crystalline CePO 4 species shows high activity only at high temperature because of its poor redox property. Therefore, it can be inferred that amorphous and crystalline structures on CePO 4 catalyst can be the efficient active species of NH 3 -SCR at low and high temperature, respectively.
研究领域:
化学工程
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催化科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2021
·Vol. 11
·期 7
·2471-2479
·
IF 6.119
Tianying Xie,Limei Cao,Wei Sun,Ji Yang
Severe conditions involved in hydrogen storage and transportation limit the practical applications of hydrogen denitration reaction. In this paper, we developed a new process that consists of methanol steam reforming inline hydrogen production coupled with denitration, which reduces the threshold use of hydrogen. The bifunctional CuZnOx–X–MnPdOz@Ni catalyst prepared in this paper could achieve inline hydrogen production through the CuOx center and reduce NOx by the MnPdOz center. The optimal CuZnOx–CeZrOy–MnPdOz@Ni candidate catalyst could maintain over 90% denitration efficiency under conditions: GHSV = 22 000 h−1 + nmethanol : nwater = 1 : 1.3 + 800 ppm NO at 150 °C. We conducted various characterization methods to reveal the valence state distribution of the promising catalyst. The experimental results indicated that the inline hydrogen selective catalytic reduction of NO is a promising strategy for green, efficient, and sustainable NOx control technology.
研究领域:
化学工程
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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
危险品化学品经营许可证（带存储）