JOURNAL OF RARE EARTHS
·
2022
·
IF 4.632
Yandi Cai,Peng Yang,Qinglong Liu,Kaili Ma,Wenxin Ma,Wang Song,Qiuhui Qian,Fei Gao,Wei Tan,Lin Dong
Sulfation treatment has been widely used to promote the catalytic performance of ceria (CeO 2 ) based catalysts for the selective catalytic reduction of NO by NH 3 (NH 3 -SCR of NO). Praseodymium oxide (PrO x ), another commonly used rare earth material with similar structural properties as CeO 2 , also shows satisfactory redox properties due to the facile redox cycle of Pr 3+ ↔ Pr 4+ . In this work, gas phase sulfation treatment with varied duration was performed on PrO x at 200 °C, and the NH 3 -SCR activity of sulfated PrO x was evaluated. Based on the results of systematic characterizations (e.g., N 2 -physisorption, NH 3 oxidation , NO oxidation, in situ diffuse Fourier transform infrared spectroscopy), it is revealed that the catalytic performance of sulfated PrO x is highly dependent on the sulfation time (or the amount of sulfate species deposited on PrO x ), which has a significant impact on the competitive reaction between NH 3 oxidation and NH 3 -SCR of NO, thus determining the NH 3 -SCR activity of PrO x . This work provides new insight into tuning the interaction between PrO x surface and reactants (NO, NH 3 ) via sulfation treatment, which cam guide the design and application of PrO x based catalysts for NH 3 -SCR of NO in the future.
研究领域:
化学工程
·
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
SENSORS AND ACTUATORS B-CHEMICAL
·
2020
·
IF 7.1
Weiwei Meng,Ling Wang,Huizhu Zhou,Yongguang Liu,Lei Dai
Impedimetric NH 3 sensors using Yttria-stabilized zirconia (YSZ) as solid electrolyte and spinel-type oxide as sensing electrode (SE) were fabricated. Phase angle (θ) was employed as response signals to evaluate their sensing performance, as a comparison, modulus value (|Z|) response was also examined. The SE materials with nanostructure were in-situ introduced into the YSZ porous skeleton by impregnation technique. A series of spinel-type oxide MFe 2 O 4 (M = Ni, Zn and Co) were examined, and among these oxides, NiFe 2 O 4 was found to be the most excellent SE for NH 3 sensor. Sensing performance of the sensor was optimized by adjusting the loading amount and calcination temperature of the sensing material NiFe 2 O 4 and the sensor exhibits the best performance when the loading amount is 0.585 mg and the calcination temperature is 800 °C. Sensing performance of the sensor was tested in 50−1000 ppm NH 3 with temperature varying from 400 to 650 °C. Compared with modulus value (|Z|), θ as response signal improves sensing performance of NH 3 sensor. The sensor exhibits short recovery time, high sensitivity and reproducible response at 600 °C. The sensor has good anti-interference capability to CO 2 , CH 4 , H 2 , NO 2 and NO, but O 2 and relative humidity (RH) have a certain effect on sensing performance.
研究领域:
材料科学
·
传感器技术
✓ 已验证
DOI
高影响因子
Journal of Environmental Sciences
·
2023
·
IF 6.9
Songjin Ko,Xiaolong Tang,Fengyu Gao,Honghong Yi,Hengheng Liu,Ning Luo
In this work, the phosphomolybdate (HPMo) modification strategy was applied to improve the N 2 selectivity of MnCo-BTC@SiO 2 catalyst for the selective catalytic reduction of NO x , and further, the mechanism of HPMo modification on enhanced catalytic performance was explored. Among MnCo-BTC@SiO 2 -x catalysts with different HPMo concentrations, MnCo-BTC@SiO 2 -0.75 catalyst exhibited not only the highest NH 3 -SCR performance (∼95% at 200-300°C) but also the best N 2 selectivity (exceed 80% at 100-300°C) due to the appropriate redox capacity, greater surface acidity. X-ray photoelectron spectrometer (XPS) and temperature programmed reduction of H 2 (H 2 -TPR) results showed that the modification with HPMo reduced the oxidation-reduction performance of the catalyst due to electron transfer from Mo 5+ to Mn 4+ /Mn 3+ and prevent the excessive oxidation of ammonia adsorption species. NH 3 temperature-programmed desorption of (NH 3 -TPD) results showed that the modification with HPMo could significantly improve the surface acidity and NH 3 adsorption, which enhance the catalytic activity and N 2 selectivity. In-situ diffused reflectance infrared Fourier transform spectroscopy (in-situ DRIFTS) revealed that modification with HPMo increased significantly the amount of adsorbed NH 3 species on the Bronsted acid site and C B / C L , it suppressed the production of N 2 O by inhibiting the production of NH species, the deep dehydrogenation of ammonia adsorption species. This study provided a simple design strategy for the catalyst to improve the low-temperature catalytic performance and N 2 selectivity.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
PubMed
高影响因子
ENERGY & FUELS
·
2025
·
IF 5.3
Fang Wang,Xueyan Wu,Yuxuan Han,Yan Lv,Jixi Guo,Xiaoman Li,Yaping Zhang
In cement kiln flue gas emissions, high concentrations of alkali and alkaline earth metals cause the deactivation of the NbCe/Ti catalysts, significantly reducing their operational lifespan under industrial conditions. Here, the NbCe-loaded titanium nanotubes (NbCe/TiNTs) catalyst has been synthesized via hydrothermal and impregnation methods. The NbCe/TiNTs catalyst exhibits superior resistance to potassium (K) and calcium (Ca) poisoning. Notably, NbCe/TiNTs catalyst maintains high NOx conversion across a wide temperature range (192–350 °C). The 5Ca-NbCe/TiNTs and 3K-NbCe/TiNTs catalysts achieve a 90% NOx conversion at 235 and 242 °C, respectively, demonstrating remarkable resistance to K and Ca poisoning. The results indicate that TiNTs supports enhance both the specific surface area and surface acid sites of the catalyst, synergistically improving its resistance to K and Ca poisoning. Furthermore, an in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) study elucidates selective catalytic reduction with the NH3 (NH3-SCR) reaction mechanism, revealing dual contributions from both the Eley–Rideal (E–R) and Langmuir–Hinshelwood (L–H) mechanisms on the catalyst. This work provides a research direction for enhancing the alkali poisoning resistance of NOx removal catalysts.
研究领域:
环境催化
·
材料科学
·
化学工程
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
CHEMICAL RESEARCH IN CHINESE UNIVERSITIES
·
2018
·Vol. 34
·期 4
·661-664
·
IF 1.248
Yi Ting,Li Jingwei,Zhang Yibo,Yang Xiangguang
Hollow-ZSM-5 was synthesized by a traditional hydrothermal method without alcohol, and a novel na-no-sized Ce-Cu/hollow ZSM-5 sample was prepared by conventional incipient wetness impreganation. The catalysts were characterized by TEM, SEM, XRD, NMR and N 2 adsorption-desorption. The results indicate that the hollow-ZSM-5 has a good MFI structure with large surface area. The synthesized CeO 2 -CuO/hollow ZSM-5 showed an excellent catalytic activity for NO x conversion(90% NO x conversion were obtained) in the temperature range of 340–550 °C under GHSV=480000 mL·g ‒1 ·h ‒1 due to its appropriate redox ability and acidity.
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
Green Energy & Environment
·
2019
·
IF 0
Ge Li,Baodong Wang,Qi Sun,Wayne Qiang Xu,Ziran Ma,Hongyan Wang,Daojun Zhang,Jiali Zhou
A combined acid–alkali hydrothermal method was used to prepare fly ash –derived SAPO-34 molecular sieves from a thermal power plant in Inner Mongolia (China). The specific surface area of the prepared fly-ash-derived SAPO-34 molecular sieves was 579 m 2 g −1 , the total pore volume was about 0.27 cm 3 g −1 , and the pore size was 0.56 nm; the molar ratios of Al 2 O 3 :P 2 O 5 :SiO 2 were 1:0.86:0.45. Cu/SAPO-34 catalysts were prepared by impregnation of low-cost fly-ash-derived SAPO-34 molecular sieves as a support and tested in selective catalytic reduction with NH 3 (NH 3 -SCR). Powder X-ray diffraction (XRD), N 2 adsorption–desorption, X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR), NH 3 temperature-programmed desorption (NH 3 -TPD), electron paramagnetic resonance (EPR), nuclear magnetic resonance (NMR), X-ray fluorescence analysis (XRF) and scanning electron microscopy (SEM) were used for catalyst characterization and investigation of the relationships between the catalyst structure and the catalytic activity. The actual silica:alumina ratio of the molecular sieves did not increase with increasing Cu loading, indicating that increasing the Cu loading does not change the original structure of the SAPO-34 molecular sieves. The XRF and NMR results showed that replacement by Cu results in more Si islands. The molecular sieve acidity decreased because of the increased number of Si islands. The NH 3 -TPD results showed that for the Cu/SAPO-34 catalysts there was a low correlation between the low-temperature activity and the amount of acidic sites. SCR activity is closely related to the location of Cu. The 4.47Cu/SAPO-34 catalyst has the highest isolated Cu 2+ showed the highest NH 3 -SCR activities (> 90%) at 250–350 °C. This work opens up new avenues for recycling fly ash formed in coal-fired power plants (reducing environmental pollution) and developing low-cost SCR catalysts for NO x pollution control.
研究领域:
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
FUEL
·
2021
·
IF 6.609
Zhanzhi Ge,Yuesong Shen,Sasa Gu
The catalyst for selective catalytic reduction of NO x at high temperatures is significantly demanded by current gas-fired exhaust purification. In this work, the complex oxides composed of two different structures of ZrO 2 -WO 3 and WO 3 /ZrO 2 with zirconium as the main component were prepared for NH 3 -SCR of NO at high temperatures by blending method and equal volume impregnation method, respectively. Combined with XRD, NH 3 -TPD, FE-SEM, BET and in situ DRIFTS characterization, the effects of component optimization of two kinds of ZrO 2 and WO 3 complex oxides on the performance for NH 3 -SCR of NO were mainly studied. The optimal compatibility of ZrO 2 and WO 3 complex oxides was determined, and the corresponding N 2 selectivity and anti-interference ability of water vapor and SO 2 were further investigated. Results showed that the performance of ZrO 2 -WO 3 prepared by blending method for NH 3 -SCR of NO was significantly better than that of WO 3 /ZrO 2 prepared by impregnation method. The ZrO 2 -WO 3 containing 20% WO 3 has the best performance in NH 3 -SCR of NO with NO conversion higher than 90% and N 2 selectivity higher than 90% at 450–650 °C, and the performance was not affected by SO 2 , slightly affected by competitive adsorption of water vapor at 450 °C and not disturbed by water vapor above 500 °C. Further investigation showed that the NH 3 -SCR of NO over the ZrO 2 -WO 3 reaction followed both L-H and E-R mechanisms. Characterization analysis revealed that ZrO 2 -WO 3 has finer microscopic particles, larger specific surface area, higher acid amount and stronger acid strength than WO 3 /ZrO 2 .
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
JOURNAL OF RARE EARTHS
·
2019
·
IF 2.846
Lei Chen,Ding Wang,Jiadao Wang,Duan Weng,Li Cao
The CeO 2 -TiO 2 (CeTi) and CeO 2 /WO 3 -TiO 2 (CeWTi) catalysts were prepared by sol-gel method. The as-prepared catalysts were hydrothermally treated at 760 °C for 48 h in air containing 10 vol% H 2 O to obtain the hydrothermal aged catalysts. The sulfur aged catalysts were treated at 400 °C with 100 ppm SO 2 , 10% water vapor, air balance for 48 h and catalysts. The powder X-ray diffraction (XRD) and Raman results indicate that the crystallization of hydrothermal aged catalysts is more serious than sulfur aged catalysts. In addition, tungsten species can stabilize the CeTi catalyst from grain growth. According to the results of in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS), temperature-programmed desorption of ammonia (NH 3 -TPD), H 2 temperature-programmed reduction (H 2 -TPR) and ammonia oxidation , the aging process leads to loss of surface area, redox properties, surface acidities and surface ceria concentration, especially for the hydrothermal aging. The NH 3 -NO/NO 2 SCR performances of sulfur aged catalysts are better than that of hydrothermal aged catalysts. Compared with CeTi catalyst, the addition of tungsten inhibits the crystallization of catalyst. So that more acid sites and active sites are retained. This is also the reason why tungsten addition improves the NH 3 -NO/NO 2 SCR performance of CeTi catalyst.
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
Molecular Catalysis
·
2022
·
IF 5.089
Yiqing Zeng,Fengye Lyu,Yanan Wang,Shule Zhang,Qin Zhong,Zhaoxiang Zhong
High N 2 O selectivity of MnO x -TiO 2 catalyst hinders its development in ammonia selective catalytic reduction (NH 3 -SCR) of NO x . Herein, a series of MnO x -TiO 2 catalyst with different Mn/Ti ratio were prepared by wet-impregnation method to study the N 2 O formation during ammonia selective catalytic reduction (NH 3 -SCR) of NO x from the perspective of catalyst. It is found that MnO x and TiO 2 species are the mainly redox and acid sites for the NH 3 -SCR denitration reaction over MnO x -TiO 2 catalyst, respectively. As the Mn/Ti ratio increases, MnO x species layer expanded on TiO 2 support, leading to increase of redox sites but decrease of surface acid sites. These changes contribute to the occurrence of the no-selective oxidation of NH 3 on MnO x species and the over-activation of NH 3 at Mn-Ti interface, resulting in the formation of N 2 O via the route of 2NH 3 + 2O 2 → N 2 O + 3H 2 O and 4NO + 4NH 3 + 3O 2 → 4N 2 O + 6H 2 O, respectively. Through this work, it can be speculated that both improving MnO x dispersion and increasing surface acidity of catalyst are feasible strategy for suppressing the N 2 O formation on MnO x -TiO 2 .
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
FUEL
·
2023
·
IF 7.4
Guoquan Liu,He Zhang,Pengfei Wang,Yi Li,Xueyue Mi,Sihui Zhan
Reducing the poisoning effect of alkaline earth metals over catalysts in industrial fields presents a great challenge to selective catalytic reduction (SCR) of NO x with ammonia. Herein, we successfully introduce sulfates to the surface of supported manganese-based oxides (Nb/MnO 2 -S) for trapping calcium species, and Nb/MnO 2 -S catalyst with superior low-temperature performance and calcium-resistant property still exhibits excellent de-NO x activity in a wide operating temperature window (175–350 °C, over 80 % NO x conversion with a gas hourly space velocity of 60,000 h −1 ) after calcium poisoning. In this case, the addition of sulfates increased the quantity of chemisorbed oxygen on Nb/MnO 2 -S, thus accelerating the redox cycle in NH 3 -SCR reaction. Significantly, compared with calcium-poisoned Nb/MnO 2 , relevant spectroscopy analysis and theoretical calculations further reveal that sulfates species prefer to interact with calcium and release the Nb active sites, which maintains the efficient NH 3 adsorption and preserves a large amount of Brønsted acid sites over calcium-poisoned Nb/MnO 2 -S, thus promoting calcium-resistant performance. This work will provide a general strategy to develop calcium-resistant SCR catalysts with low-temperature activity for industrial applications.
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
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
·
环境科学
✓ 已验证
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
危险品化学品经营许可证（带存储）