Catalysis Science & Technology
·
2023
·Vol. 13
·期 18
·5435-5448
·
IF 5
Xinyue Hu,Jialing Chen,Shaokang He,Tingyu Liang,Shenke Zheng,Lijun Lu,Chenxi Hao,Kaixin Chen,Tingting Li,Lan Yi,Li Guo,Xiaoqin Wu
Three OP-Fe-FER-x zeolites (with an FER structure) synthesized by a one-pot method with different Si/Al ratios (x = Si/Al =10–30) and similar iron contents (5.4–5.6 wt%) were compared with commercial IM-Fe/SSZ-20 zeolite (with a CHA structure) prepared by an incipient wetness impregnation method to investigate their catalytic activity and hydrothermal stability for the selective catalytic reduction reaction of NOx with NH3 (NH3-SCR). For both fresh (without hydrothermal aging treatments) and aged (with hydrothermal aging treatments) zeolites, the NOx conversions of OP-Fe-FER-x zeolites are much higher than that of IM-Fe/SSZ-20 zeolite, suggesting that the OP-Fe-FER-x zeolites are better catalysts for NH3-SCR than the commercial IM-Fe/SSZ-20 zeolite. Compared with the fresh zeolites, the NOx conversions of all four aged zeolites decrease in the low-temperature range (100–300 °C), while they increase at high temperatures (450–550 °C) to different extents. Based on XRD, N2 physisorption, NH3-TPD, UV-vis, XPS and H2-TPR experiments, the hydrothermal aging process of the OP-Fe-FER-x zeolites is depicted, which consists of partial collapse of the zeolite framework, removal of framework aluminum and iron atoms, and transformation and aggregation of iron species. Detailed characterization reveals that the OP-Fe-FER-x zeolites are more stable than the IM-Fe/SSZ-20 zeolite during the hydrothermal aging treatments. The obvious decline of NH3-SCR catalytic activity for the aged zeolites in the low-temperature range is mainly attributed to the transformation and aggregation behaviors of active isolated Fe3+ species. As for the increase of NH3-SCR activity for the aged zeolites at the high temperatures (450–550 °C), it is mainly attributed to the suppression of the NH3 oxidation side reaction due to the deteriorated NH3 storage capacity because of the loss of massive acid sites during the hydrothermal aging treatments.
研究领域:
化学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
RESEARCH ON CHEMICAL INTERMEDIATES
·
2018
·Vol. 44
·期 5
·3455-3474
·
IF 1.674
Sun Xiao,Guo Rui-tang,Li Ming-yuan,Sun Peng,Pan Wei-guo,Liu Shu-ming,Liu Jian,Liu Shuai-wei
Fe was used as the modifier to improve the performance of CeZr 2 O
x
catalyst for the selective catalytic reduction (SCR) reaction with ammonia. Experimental results revealed that proper Fe species (Fe/Ce molar ratio = 2) could effectively improve the SCR activity of CeZr 2 O
x
, along with the elevated resistance to SO 2 and H 2 O. The characterization results including BET, XRD, H 2 -TPR and NH 3 -TPD confirmed that Fe species in Fe 2 CeZr 2 O
x
catalyst could inhibit the formation of ZrO 2 crystals and lead to higher reducibility and surface acidity. In addition, more Ce 3+ and surface active oxygen species could be detected on Fe 2 CeZr 2 O
x
compared with CeZr 2 O
x
. By means of in situ DRIFT technique, it could be deduced that the SCR reaction process over Fe 2 CeZr 2 O
x
was accelerated mainly through theL–H pathway due to the advanced adsorption of NH 3 and NO
x
species, along with the promoted NO conversion to NO 2 . Therefore, the modification of CeZrO
x
catalyst by Fe had a significant stimulation effect on its low-temperature SCR performance.
研究领域:
催化化学
·
环境科学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2022
·Vol. 12
·期 4
·1245-1256
·
IF 6.177
Jie Yang,Shan Ren,Mingming Wang,Zhichao Chen,Lin Chen,Lian Liu
Ce–Ti catalysts were considered as a promising replacement for V–Ti based catalysts for selective catalytic reduction (SCR) of nitrogen oxides (NO and NO2) with NH3. In this work, a CeO2/TiO2 catalyst was prepared by the impregnation method and studied by a series of in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments. The results showed that CeO2 particles grew along TiO2 faces and amorphous cerium in the lattice of TiO2, both of which are present on the CeO2/TiO2 catalyst. NH4+ might adsorb on the Ti–O–Ce structures or TiO2–CeO2 interface as Brønsted acid sites, while two types of NH4+ species were distinguished by the time-resolved spectroscopic method due to the different increasing trends. Based on the temporal evolution transient in situ DRIFTS spectra, L-NH3 had higher activity than coordinated NH3 species, which suggested that gas phase NO reacted preferentially with L-NH3. The NH4NO3 intermediate dominated the SCR reactions over the CeO2/TiO2 catalyst, which followed 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
MOLECULES
·
2025
·Vol. 30
·期 5
·1133
·
IF 4.6
Yuansong Zhou,Fengyu Gao,Lei Yi,Junyi Wang,Honghong Yi,Xiaolong Tang
In an O 2 -containing environment, achieving efficient selective catalytic reduction of nitrogen oxides (NOx) by carbon monoxide (CO) using non-noble metal catalysts remains a formidable challenge. To balance the catalytic oxidation of CO and the catalytic reduction of NOx, we need to develop a catalyst with strong reductibility and weak oxidizability for the CO selective catalytic reduction of NOx (CO-SCR) reaction in the presence of O 2 . In this study, we synthesized the CoCeOx-PVP catalyst via a coprecipitation method and employed various characterization techniques, including BET, SEM, XRD, Raman, XPS, H 2 -TPR, and O 2 -TPD. The analysis results indicate that the addition of polyvinylpyrrolidone (PVP) alters the surface structure of the catalyst, increases the particle size, and enhances the concentration of surface oxygen vacancies. These structural effects facilitate electron circulation and accelerate the migration of oxygen species, thereby improving the catalytic reduction performance of the catalyst and increasing the conversion rate of NOx. At 250 °C and with 5 vol% O 2 , the conversion rates of NOx and CO can attain 98% and 96%, respectively, accompanied by a remarkable N 2 selectivity of 99%. Following a sustained reaction period of 6 h, the conversion efficiencies of both NOx and CO remain above 95%. However, during extended testing periods, as the oxygen vacancies are progressively occupied by O 2 , the oxygen vacancies generated through the reduction of NO with CO fall short of sustaining the CO-SCR reaction over the long haul. Subsequently, the oxidation reactions of NO and CO come to dominate, resulting in a decline in the NOx conversion rate. Notably, the CO conversion rate still maintains 100% at this point. Based on the results of in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTS) experiments, we proposed a reaction mechanism for the CO-SCR process over the CoCeOx-PVP catalyst under O 2 -containing conditions. This study provides an effective strategy for the application of non-noble metal catalysts in the field of CO-SCR. Although maintaining long-term activity of the catalyst remains a challenge in the presence of O 2 , the catalyst in this study exhibits a slower deactivation rate compared to traditional non-noble metal catalysts.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF RARE EARTHS
·
2022
·
IF 4.632
Ningyuan Wang,Xiaoqiang Wang,Yue Liu,Zhongbiao Wu
Traditional vanadium-based selective catalytic reduction (SCR) deNO x catalyst can hardly adapt to the gas conditions (much high NO 2 /NO x ratio at lower temperature) of the start-up and low loading periods for a gas turbine . Therefore, a W–Ti-CeO x catalyst with NO x storage and reduction (NSR) function was developed in this work for gas turbine exhaust NO x elimination. The experimental results reveal that W–Ti-CeO x catalyst exhibits high NO 2 adsorption capacity at relatively low temperature while that is quite low for V–W/TiO 2 . The abundant surface Ce 3+ species can be mainly responsible for its high adsorption ability owing to the reaction between NO 2 and Ce 3+ to form nitrate/nitrite species and NO. Meanwhile, the adsorption capacity of W–Ti-CeO x can easily regenerate at medium–high temperature and NH 3 -SCR reaction. Furthermore, W–Ti-CeO x also shows good NH 3 -SCR activity, which can fulfill the deNO x process at high temperature. The addition of W and Ti into ceria can enhance the surface acidity and redox ability, thereby increasing the SCR activity. This work proposes a novel storage-reduction strategy for NO x elimination throughout the operation of gas turbines.
研究领域:
环境工程
·
催化
·
能源工程
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2021
·
IF 6.707
Xiaofeng Wang,Zhe Zhao,Yang Xu,Qingbo Li
A series of 3DOM-Mn x Ce y Ti z catalysts with three-dimensionally ordered macroporous (3DOM) structure were synthesized by a soft template method. The high SCR activity of the 3DOM-Mn 3 Ce 1 catalyst at low temperature was owing to the excellent redox ability and rich Lewis and Brønsted acid sites of the catalysts, which were beneficial to improve the catalytic activity. However, the strong oxidizability of MnO x resulted in the nonselective oxidation of NH 3 and generation of N 2 O, decreasing the N 2 selectivity. After addition of Ti, the redox capacity of the 3DOM-Mn 3 Ce 1 Ti 1 catalyst decreased, and the NH 3 were strongly adsorbed on the acid sites, which enhanced the N 2 selectivity with a broadened temperature window of 240–440 °C and a high GHSV of 120000 h −1 . Furthermore, both the 3DOM-Mn 3 Ce 1 and 3DOM-Mn 3 Ce 1 Ti 1 catalysts showed remarkable tolerance of H 2 O. Finally, through in situ DRIFT analysis, the Langmuir-Hinshelwood (L-H) mechanism was confirmed as the dominant reaction pathway over the 3DOM-Mn 3 Ce 1 Ti 1 catalyst.
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
Yuheng Qiao,Zhenzhen Guan,Mengyan Zhang,Gan Chen,Shifeng Zhou,Hailong Liu,Jiang Wu,Ruitang Guo,Weiguo Pan,Fangqin Li,Ping He
In this paper, a series of Fe-based catalysts with Zeolite Socony Mobil-5 (ZSM-5) as supports were synthesized using the sol–gel method to obtain the Fe/ZSM-5, Mn-Fe/ZSM-5, Cu-Fe/ZSM-5 and Cu-Mn-Fe/ZSM-5 catalysts. The synthesized catalysts were examined and characterized via catalytic activity testing, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N 2 adsorption/desorption, scanning electron microscope (SEM), temperature-programmed desorption of NH 3 (NH 3 -TPD), temperature-programmed reduction with H 2 (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). The results showed that the Cu-Mn-Fe/ZSM-5 catalyst had the best catalytic performance compared with the other catalysts. In addition, Fe/ZSM-5 and Cu-Mn-Fe/ZSM-5 all exhibited excellent stability as well as good tolerance to SO 2 & H 2 O under the experimental conditions. Further characterization results showed that with co-doping of Cu and Mn, the amount of Mn 4+ , Cu + , Fe 3+ and surface chemisorbed oxygen (O β ) on the surface of Fe/ZSM-5 increased, promoting the catalytic performance. The DRIFT studies revealed that the NH 3 -SCR reaction followed both the E-R and L-H mechanism on the surface of the Fe-based ZSM-5 catalyst. The Fe-based ZSM-5 catalyst is a good candidate for NH 3 -SCR both in high reactivity and outstanding stability.
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
APPLIED SURFACE SCIENCE
·
2018
·
IF 4.439
Weiyuan Yao,Yue Liu,Zhongbiao Wu
A series of CeO 2 @Ce-O-P “multi-core@shell” catalysts were synthesized in this paper for selective catalytic reduction (SCR) of NO with NH 3 . The experimental results had showed that CeO 2 @Ce-O-P-30:3 yielded best SO 2 tolerance of an over 70% deNO x efficiency at 250 °C in the presence of 100 ppm SO 2 for 20 h, which was much higher compared to pure Ce-O-P and CeO 2 samples. Further characterization results indicated that Ce-O-P coating layer could somewhat inhibit sulfur depositing on the catalysts during SCR reaction in the presence of SO 2 , thereby protecting the active sites from SO 2 poisoning. Especially, O 2 -TPD results illustrated that a great amount of active oxygen species were retained on used CeO 2 @Ce-O-P catalyst after a long term reaction. The synergetic effect of “multi-core@shell” structure could be attributed to such enhanced performances. The “core” CeO 2 devoted abundant active oxygen sites to fulfill the SCR reaction. And the “shell” Ce-O-P could not only provide acid sites, but also protect the active oxygen species by avoiding the over-adsorption of SO 2 on the catalyst. This work could provide a new way to increase the sulfur resistance for low temperature SCR catalysts.
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
Advances in Materials Science and Engineering
·
2019
·
IF 1.399
Zhuo Yao,Dianli Qu,Yuxiang Guo,Yujing Yang,Hong Huang
Novel catalysts with high activity for the selective catalytic reduction of NO with NH3 (NH3-SCR) at low temperatures are highly demanded. In this study, mixed-node metal-organic frameworks (MOFs), e.g. Mn@CuBTC with controlled Mn composition in Cu3(BTC)2, were fabricated using postsynthetic exchange method and their structural characteristics and catalytic performances for NH3-SCR reaction were assessed. A series of analyses in terms of structure, surface morphology, texture, and chemical state determined that Mn ions were successfully incorporated into the Cu3(BTC)2 crystal lattice as well as adsorbed on the walls of nanopores in the framework. The pore sizes can be finely tuned in the presence of Mn ions in the cages, which significantly suppressed water adsorption. The NH3-SCR activity of Mn@CuBTC exhibited nearly 100% NOx conversion rate in the temperature range (230–260°C). The superior NH3-SCR performance is attributed to the proper pore sizes, reduced water content, and the synergistic effect between manganese and copper ions in the MOF structure, which enhanced NH3 bound to the active Lewis sites.
研究领域:
材料科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2020
·
IF 5.825
Ye Ma,Shichao Han,Qinming Wu,Longfeng Zhu,Huimin Luan,Xiangju Meng,Feng-Shou Xiao
The metal-exchanged zeolites as catalysts have been widely applied in many catalytic reactions , but their syntheses are environmentally unfriendly due to the multiple steps such as ion-exchange for the formation of a large amount of wastes. Herein, we for the first time report a method for one-pot fabrication of metal-zeolite catalysts (M-SSZ-13, M-Beta, M-ZSM-5, and M-EU-1; M = Cu, Co, Ni) from a combination of solvent-free and sodium-free routes by mixing, grinding, and heating the raw materials of aluminosilicate gel, organic templates, and metal-amine complexes. As a typical example, Cu-SSZ-13 zeolite is successfully synthesized from heating the mixture of aluminosilicate gel, organic template, and Cu-amine complex. Catalytic tests in selective catalytic reduction of NO x with NH 3 (NH 3 -SCR) show that the synthesized Cu-SSZ-13 zeolite before and after hydrothermal aging at 750 °C for 16 h are completely comparable with the commercial Cu-SSZ-13 zeolite from the conventional hydrothermal synthesis. Very interestingly, the method in this work has obvious advantages such as high yield, reduced pollutants, and simple process, which should be potentially important for practical applications of the metal-zeolites in the future.
研究领域:
催化化学
·
环境科学
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Yuxin Sun,Yunshuo Wu,Yarong Bai,Xuanhao Wu,Haiqiang Wang,Zhongbiao Wu
Iridium nanocatalysts are ideal candidates for the selective catalytic reduction of NO x by CO (CO-SCR) in excess oxygen. Here, a high-performance Ir nanocatalyst supported on natural halloysite nanotubes (HNTs) was applied for the CO-SCR. The HNTs loaded with only 0.5 wt% Ir achieved 78 % NO x conversion at 250 °C in the presence of 5 % O 2 , which was the highest among catalysts with varied Ir loadings or reduction temperatures. It also possessed an excellent SO 2 and H 2 O tolerance during longevity tests. An interesting SO 2 -enhanced CO-SCR long-term stability was observed, which was ascribed to the inhibitory effects of SO 2 on the side reaction between CO and O 2 . The loading amount and the reduction temperature could modulate the size of Ir nanoparticles and the percent of Ir 0 , which were two key factors determining the CO-SCR activity. DRIFTS characterizations and DFT calculations coherently revealed the favorable adsorption sites of CO (top) and NO (hcp) on Ir nanoparticles. The Ir atoms served as a charge transfer bridge from the C atom of CO to the N atom of NO, leading to the enhanced breakage of N-O bonds. This work provides Ir/HNT as a promising CO-SCR material with high performance and robustness to tackle NO x pollution.
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
Catalysts
·
2021
·Vol. 11
·期 4
·445
·
IF 4.146
Yangyang Guo,Xiaofei Xu,Hong Gao,Yang Zheng,Lei Luo,Tingyu Zhu
Ca poisoning behavior is inevitable for high-calcium content flue gas, so V2O5-WO3/TiO2(VWT) and V2O5-WO3-CeO2/TiO2(VWCeT) catalysts with different vanadium content have been prepared and the Ca-doped catalysts are compared in this manuscript. The result shows Ce addition can both promote the NO conversion and the alkali resistance. Lower Ca addition for 0.1VWCeT catalyst promotes its oxidability and Ce modification is more suitable for low vanadium catalysts. The total acidity and the reducibility of catalysts decline after Ca doping, and the reducibility of the active species on catalysts has been strengthened by Ce addition. CeO2based catalysts with lower Ca loading struggle to resist sulfur poisoning, while higher Ca loading favors SO2adsorption and also physically reduces the cerium acidification process. In the presence of SO2, additional Brønsted acid sites are formed in Ca rich catalyst. The dynamic NH3adsorption has been investigated, shows that Ca doping content on catalyst is critical for SCR reaction, and the catalyst is more susceptible to SO2initially in alkali flue gas during the actual application, but the sulfur resistance may increase with the alkali-poisoning effect aggravated by Ca doping.Keywords:Ca-poisoning;SCR reaction;NO reduction;V2O5-WO3/TiO2and V2O5-WO3-CeO2/TiO2catalysts;SO2and water;NO removal efficiency
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）