Journal of Environmental Sciences
·
2021
·
IF 5.565
Chang Cui,Yan Zhang,Wenpo Shan,Yunbo Yu,Hong He
Alumina supported Pd catalyst (Pd/Al 2 O 3 ) is active for complete oxidation of methane, while often suffers transient deactivation during the cold down process. Herein, heating and cooling cycle tests between 200 and 900°C and isothermal experiments at 650°C were conducted to investigate the influence of NO x on transient deactivation of Pd/θ-Al 2 O 3 catalyst during the methane oxidation. It was found that the co-fed of NO alleviated transient deactivation in the cooling ramp from 800 to 500°C, which was resulted from the in situ formation of NO 2 during the process of methane oxidation. Over the Pd/θ-Al 2 O 3 , thermogravimetric analysis and O 2 temperature programmed oxidation measurements confirmed that transient deactivation was due to the decomposition of PdO particles and the hysteresis of Pd reoxidation, while the metal Pd entities were less active for methane oxidation than the PdO ones. CO pulse chemisorption and scanning transmission electron microscopy characterizations rule out the NO 2 effect on Pd size change. Powder X-ray diffraction and X-ray photoelectron spectroscopy characterizations were used to obtain palladium status of Pd/θ-Al 2 O 3 before and after reactions, indicating that in lean conditions at 650°C, the presence of NO 2 increases the content of active PdO on the catalyst surface, thus benefits methane oxidation. Homogeneous reaction between CH 4 , O 2 , and NO x may be partially responsible for the alleviation above 650°C. The interesting research of alleviation in transient deactivation by NO x , the components co-existing in exhausts, are of great significance for the application.
研究领域:
催化化学
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环境科学
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DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 39
·24144-24155
·
IF 3.361
Xingdong Yang,Jiyan Qu,Linxi Wang,Jianhong Luo
In an attempt to realize the efficient treatment of NOx, a mixed catalyst of Ti3+ self-doped TiO2−x and γ-Al2O3 was constructed by reducing commercial TiO2. The degradation effect on NOx was evaluated by introducing the mixed catalyst into a coaxial dual-dielectric barrier reactor. It was found that the synthesized TiO2−x could achieve considerable degradation effects (84.84%, SIE = 401.27 J L−1) in a plasma catalytic system under oxygen-rich conditions, which were better than those of TiO2 (73.99%) or a single plasma degradation process (26.00%). The presence of Ti3+ and oxygen vacancies in TiO2−x resulted in a relatively narrow band gap, which contributed to catalyzing deeply the oxidation of NOx to NO2− and NO3− during the plasma-induced “pseudo-photocatalysis” process. Meanwhile, the TiO2−x showed an improved discharge current and promoted discharge efficiency, explaining its significant activation effect in the reaction. Reduced TiO2−x could achieve an impressive degradation effect in a long-time plasma-catalysis process, and still maintained its intrinsic crystal structure and morphology. This work provides a facile synthesis procedure for preparing Ti3+ self-doped TiO2−x with practical and scalable production potential; moreover, the novel combination with plasma also provides new insights into the low-temperature degradation of NOx.
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
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2025
·
IF 21.1
Yarong Bai,Houlin Wang,Chao Jin,Chuan Gao,Shangchao Xiong,Zhengjun Gong,Yue Peng,Junhua Li
Precision modulation of metal-support interactions is essential for optimizing catalytic activity and selectivity in automotive exhaust treatment. In this study, we systematically regulate the strength of Pt-CeO 2 interaction by altering Pt anchoring strategies on Al 2 O 3 , thereby achieving a controlled balance between NO x reduction efficiency and by-product formation. Comprehensive structural and spectroscopic analyses reveal that increasing the interaction strength (PtCeAl-mix
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
ACS Catalysis
·
2022
·
IF 13.7
Yongjun Ji,Shaomian Liu,Shaojia Song,Wenqing Xu,Liang Li,Yu Zhang,Wenxing Chen,Huifang Li,Jingang Jiang,Tingyu Zhu,Zhenxing Li,Ziyi Zhong,Dingsheng Wang,Guangwen Xu,Fabing Su
Pt-based catalysts are promising for the selective catalytic reduction of NOx by CO (CO-SCR), but some technical issues hinder their practical application, including the high Pt loading needed, high reduction temperature, and the low tolerance toward SO2. Here, we report a novel Pt catalyst for CO-SCR, which has negatively charged single-atom Pt embedded on CuO squares, and the latter is supported on CoAlO nanosheets. This Pt–CuO/CoAlO catalyst with an ultra-low Pt loading (0.02 wt %) exhibited 91% NO conversion and 80% N2 selectivity in 3% O2 at 200 °C. More importantly, it showed almost no activity loss in 200 ppm SO2 over a 15 h test. The theoretical calculations reveal that the negatively charged Pt has a stronger NO adsorption ability than the positively charged Pt, and Cu serves as the CO adsorption site. The much-weakened SO2 adsorption on Pt–CuO/CoAlO relative to the NO and CO adsorption effectively avoids the catalyst poisoning by SO2.
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
ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH
·
2020
·Vol. 27
·期 22
·27663-27673
·
IF 3.056
Liu Yuan-zhen,Xu Qi-yan,Guo Rui-tang,Duan Chao-peng,Wu Gui-lin,Miao Yu-fang,Gu Jing-wen
The Cu/TiO 2 catalysts with the addition of Eu were developed by the sol-gel way for the selective catalytic reduction (SCR) of NO x by NH 3 . Activity tests revealed that CuEu/TiO 2 -0.15 catalyst showed the optimal de-NO x performance in a wide temperature range (150–300 °C), along with an admirable SO 2 tolerance. According to characterization analysis, the relationship between the NH 3 -SCR performance and physicochemical characters of samples was explored. The adjunction of Eu on Cu/TiO 2 catalyst can contribute to the formation of a large amount of Cu 2+ , adsorbed oxygen, and acid sites on the catalyst surface. Moreover, the Eu addition on Cu/TiO 2 is favorable to the generation of activated NO x and NH 3 substances adsorbed on the catalyst surface, which would conduce to the NH 3 -SCR process by Langmuir-Hinshelwood (L-H) mechanism effectively.
研究领域:
环境科学
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催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
FUEL
·
2021
·
IF 6.609
Hanzi Liu,Yi Zhang,Haiming Wang,Changfu You
Selective non-catalytic reduction of NOx (SNCR) with NH 3 is commonly used in industrial facilities like circulating fluidized bed (CFB) furnaces. However, the strongly temperature-dependent de-NOx feature confines its applications in a specific temperature range (900–1050 °C). Here, we report a new strategy on using Fe-Ni-W exchanged zeolite (0.5FNW-H) as a catalyst to extend the SNCR temperature window. In the CFB reactor, a significant NOx conversion improvement ranging from 14.1% to 80.9% was achieved at 700 to 850 °C by applying the developed catalyst. Catalyst dosage of 4500 h −1 (GHSV), a particle diameter of 0.1–0.3 mm, and NH 3 injection position at the dense-phase zone were found preferred for NOx reduction with the highest efficiency of ~85% at 700 °C. The physicochemical properties of the catalysts remained stable after the circulating reactions in the CFB reactor. The developed catalyst is particularly applicable for improving the SNCR performance when the thermal power plants are operated at low loads.
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
·
2014
·
IF 4.058
Jiancheng Wang,Zhaoliang Peng,Ying Chen,Weiren Bao,Liping Chang,Gang Feng
Cu-SSZ-13/cordierite monolithic catalyst was prepared by in situ hydrothermal synthesis method. The physicochemical properties of the as-prepared Cu-SSZ-13/cordierite were investigated by X-ray diffraction analysis, scanning electron microscopy, transmission electron microscopy, N 2 -adsorption, inductively coupled plasma, X-ray photoelectron spectroscopy, and solid-state NMR techniques. The removal of nitrogen oxides (NO x ) from simulated diesel vehicle exhaust gas was performed using fixed-bed reactor. The effects of crystallization time and addition of HF during hydrothermal synthesis, reaction space velocity, and aging treatment of catalyst on the catalytic performances of NO x reduction reactions were investigated. The results indicate that the optimum crystallization time was 72 h. Highly crystalline structure of zeolite Cu-SSZ-13 was formed, in a close combination with a carrier, via one step hydrothermal process. Cu-SSZ-13/cordierite showed excellent DeNO x performance for selective catalytic reduction (SCR) and anti-aging properties in a simulated diesel exhaust gas under a high space velocity. At a high space velocity of 72,000 h −1 , the highest conversion and N 2 selectivity of 94% and 90%, respectively, were achieved. After the aging for 50 h at 720 °C, NO x reduction rate was still >80% in the temperature range of 350–550 °C. The larger height to diameter ratio of the same catalysts enhanced the NH 3 -SCR catalytic activity and broadened the active temperature window. The addition of HF increased the catalytic activity and anti-aging performance of the sample.
研究领域:
催化材料
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环境科学
·
化学工程
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DOI
高影响因子
CHINESE JOURNAL OF CATALYSIS
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2020
·
IF 6.146
He Ma,Changhua Wang,Songmei Li,Xintong Zhang,Yichun Liu
Semiconductor oxides are widely used to achieve photocatalytic removal of NO x (NO and NO 2 ) species. These materials also exhibit enhanced oxidation ability in thermally assisted photocatalysis ; however, many of them tend to be deactivated at high relative humidity (RH) levels. In the case of the benchmark P25 TiO 2 photocatalyst, we observe a significant decrease in non-NO 2 selectivity from 95.02% to 58.33% when RH increases from 20% to 80%. Interestingly, the porous TiO 2 (B) microspheres synthesized in this work exhibit 99% selectivity at 20% RH; the selectivity remains as high as 96.18% at 80% RH. The high humidity tolerance of the TiO 2 (B) sample can be ascribed to its strong water desorption capacity and easy O 2 adsorption at elevated temperatures, which reflects the fact that the superoxide radical is the main active species for the deep oxidation of NO x . This work may inspire the design of efficient photothermal catalysts with application in NO x removal in hot and humid environments.
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
高影响因子
RSC Advances
·
2018
·Vol. 8
·期 5
·2586-2592
·
IF 2.936
Boyang Xu,Youlin Liu,Yuesong Shen,Shemin Zhu
A facile method is to prepare novel CeMoxOy-clay hybrid catalysts with layered structures by using organic cation modified clay as support. During the preparation process, cerium cations and molybdate anions are easily adsorbed and impregnated into the interlamellar space of the organoclay, and after calcination they undergo transformation to highly dispersed CeMoxOy nanoparticles within the interlamellar space of the clay. As expected, the prepared CeMo0.15Ox-OC-T catalysts with layered structures had high selective catalytic reduction (SCR) activity such as high NOx conversion of >90% in the wide temperature range of 220–420 °C. Meanwhile, they also exhibit high stability and tolerance to water vapor (5 vol%) and SO2 (200 ppm), demonstrating that these novel catalysts could serve as a good alternative for NH3-SCR in practical application.
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
产品关联
DOI
PubMed
高影响因子
AICHE JOURNAL
·
2019
·Vol. 65
·期 10
·e16684
·
IF 3.463
Lei Song,Kui Ma,Wen Tian,Junyi Ji,Changjun Liu,Siyang Tang,Wei Jiang,Hairong Yue,Bin Liang
A novel FeTiSO x catalyst prepared by a simple hydrolysis coprecipitation method was used for the selective catalytic reduction (SCR) of NO x with NH 3 , which exhibited high catalytic activity (NO x conversion of >97% and N 2 selectivity of >95%) and tolerance for both H 2 O and SO 2 at a broad temperature window of ~325–475°C. The characterization results showed that the formation of Fe–O–Ti and Fe–O–S species could significantly enhance the acidic sites of the catalyst, which play an important role in NH 3 absorption and their catalytic activity. The Fe 3+ ions in the bulk anatase TiO 2 could significantly enhance the redox properties for the SCR reaction and suppress the side reaction of NH 3 oxidation to NO or N 2 O. In addition, the reaction mechanism was discussed based on in situ diffuse reflectance infrared Fourier transform spectroscopy measurements and kinetic investigation, indicating that the reaction was dominated by the Eley–Rideal mechanism over the FeTiSO x catalyst.
研究领域:
环境科学
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催化化学
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2021
·
IF 13.273
Liyuan Duan,Guoqiang Li,Shuting Zhang,Hongyu Wang,Yongle Zhao,Yongfa Zhang
In this study, graphitized carbon nitride photocatalysts were successfully prepared by using the desulfurized waste liquid extracting salt from coking plants. The NO x removal efficiency of g-C 3 N 4 synthesized using ammonium thiocyanate (NH 4 SCN), ammonium thiosulfate ((NH 4 ) 2 S 2 O 3 ) and ammonium sulfate ((NH 4 ) 2 SO 4 ) with different mass ratios were evaluated. The results showed that due to the addition of (NH 4 ) 2 S 2 O 3 and (NH 4 ) 2 SO 4 a large amount of sulfur-containing gas was released during pyrolysis, which significantly increased the specific surface area and pore volume of the photocatalysts. The release of sulfur-containing gas also resulted in the incorporation of sulfur, and due to this doping process the band gap of the photocatalyst was widened to 2.94 eV, thus enhancing its visible light response. C vacancies were formed in the hepazine ring, which increased the electron density around the N–(C) 3 bridge bond and formed an electron trapping center, thus inhibiting the recombination of charge carriers. The photocatalysts had increased O 2 adsorption capacity and increased number of amino groups on their surface. This facilitated the rapid generation and consumption of reactive oxygen species, inhibited the accumulation of NO 2 on the surface, reduced the production of NO 2 , thus improving the NO x removal efficiency of the photocatalysts. The principle of using “waste for waste control” was achieved, and a new method for nitrogen oxide removal was provided.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
Catalysis Science & Technology
·
2015
·Vol. 5
·期 4
·2260-2269
·
IF 5.426
Qiulin Zhang,Xin Liu,Ping Ning,Zhongxian Song,Hao Li,Junjie Gu
Mesoporous Ce–Ti–MoOx catalysts have been prepared by stabilization with an in situ formed carbon template and used for selective catalytic reduction of NOx with NH3 (NH3-SCR). The Ce–Ti–MoOx catalysts were characterized by N2 adsorption–desorption, XRD, HR-TEM, H2-TPR and XPS analysis. It was found that the stabilization with a carbon template obviously improved the NOx conversion of the Ce–Ti–MoOx catalyst and the pore distribution. The Ce–Ti–MoOx catalyst stabilized with a carbon template at 850 °C in N2 exhibited the best NH3-SCR activity and showed a uniform mesopore distribution, and more than 90% NOx conversions were obtained at 175–425 °C with a GHSV of 60 000 h−1. The high stabilization temperature with a carbon template in N2 not only led to an increase in specific surface area, pore volume and low-temperature SCR activity, but also contributed to the enhanced redox properties, highly dispersed titanium or molybdenum species and narrow mesopore distribution. The treatment of Ce–Ti–MoOx with a high calcination temperature for removal of the carbon template led to a drastic decrease in surface area, an abrupt decrease in surface oxygen and cerium, production of rutile TiO2, and a correspondingly low SCR activity.
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
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