APPLIED CATALYSIS A-GENERAL
·
2017
·
IF 4.339
Baohuai Zhao,Rui Ran,Xingguo Guo,Li Cao,Tengfei Xu,Ze Chen,Xiaodong Wu,Zhichun Si,Duan Weng
Mn/Ce/Ti and Mn/Ce/Nb/Ti catalysts were synthesized using a precipitation method and their catalytic activities for NO selective reduction with NH 3 at low temperatures were evaluated. Nb doping not only improved the activity of the catalyst over a wide temperature range but also restricted the generation of NO 2 and N 2 O. The Mn/Ce/Nb/Ti catalyst displayed 100% NO conversion from 150 to 250 °C and >90% N 2 selectivity below 250 °C. The specific surface area of the catalyst was increased and its surface acidity was strengthened after Nb doping. Moreover, Nb doping increased the NO oxidation ability and lowered the NH 3 oxidation activity of the catalyst. All the above factors contributed to enhancing the overall NH 3 -SCR performance of the Mn/Ce/Nb/Ti catalyst compared with that of the Mn/Ce/Ti one. The long-term stability and resistance to H 2 O and SO 2 of the Mn/Ce/Nb/Ti catalyst were also evaluated.
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
CHEMICAL ENGINEERING JOURNAL
·
2021
·
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
APPLIED SURFACE SCIENCE
·
2025
·
IF 6.9
Shibo Yu,Yiqing Zeng,Mengna Zhan,Shule Zhang,Zhaoxiang Zhong
The influence of phosphorus (P) on ammonia selective catalytic reduction (NH 3 -SCR) catalysts has been the subject of considerable scrutiny. Nevertheless, the precise mechanism of its influence remains a matter of contention. Furthermore, the impact of introducing P at varying stages during catalyst preparation process and its different sites within the catalyst structure on performance is frequently disregarded, significantly hindering practical guidance for designing effective modified catalysts. In this study, a series of P-modified CeO 2 /TiO 2 catalysts were synthesized by introducing P at different preparation stages, and various of characterization and comparison experiments were conducted to elucidate the effect of introducing P at different stages on NH 3 -SCR performance of NO x . Results show that introducing P before loading CeO 2 boosts catalyst activity, whereas delaying the introduction of P results in decreased activity and a progressive decline in catalyst performance as the sequence of P introduction is postponed. P introduced earlier tends to be distributed on the surface of the TiO 2 support, which contributes to the dispersion and anchoring of Ce species. In contrast, when the introduction of P was delayed, it tended to be distributed on the surface of the active species, which led to pore plugging and active sites being covered. Secondly, the variation in loading sites resulting from alterations in the stage of P introduction significantly affected on the chemical environment of Ce species, leading to notable differences in the redox capacity of the catalysts. This is the primary reason for the considerable discrepancy in the SCR performance of the catalysts. This study revealed the sensitivity of the stage of P introduction to CeO 2 /TiO 2 catalysts, providing new insights for designing modified CeO 2 /TiO 2 catalysts.
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
Catalysis Science & Technology
·
2016
·Vol. 6
·期 14
·5543-5553
·
IF 5.287
Xin Zhao,Lei Huang,Supawadee Namuangruk,Hang Hu,Xiaonan Hu,Liyi Shi,Dengsong Zhang
A novel Zr–CeVO4/TiO2 catalyst was developed for the selective catalytic reduction (SCR) of NO with NH3. Both TiO2 nanosheets (TiO2-NS) and nanoparticles (TiO2-NP) with different crystal facets were used as supports for the catalyst. It was found that the TiO2-NS-supported catalyst showed much better activity, stability and H2O/SO2 durability than the TiO2-NP-supported catalyst. In particular, the catalyst loading amount was much lower than those of previously reported vanadate-based SCR catalysts. The crystal structures and morphologies were analysed by X-ray diffraction (XRD), Raman spectroscopy and (high-resolution) transmission electron microscopy ((HR)TEM). The redox properties, surface active species and acid sites of the catalysts were investigated through hydrogen temperature-programmed reduction (H2-TPR), X-ray photoelectron spectroscopy (XPS), ammonia and nitrogen oxide temperature-programmed desorption (NH3-TPD and NOx-TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (in situ DRIFTs) experiments. The improved activity at lower temperature was due to the presence of more active oxygen species and Brønsted acid sites, as well as the formation of NO2 on the surface of the TiO2 nanosheets which have exposed (001) facets. The enhanced stability and H2O/SO2 durability of Zr–CeVO4/TiO2-NS was due to the limited formation of NH4NO3 and (NH4)2SO4/NH4HSO4. The excellent low operation temperature, low vanadium content and absence of WO3(MoO3) in this catalyst indicated that it has promising potential as a SCR catalyst for practical applications.
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
Fengyuan Liu,Junqi Li,Hong Yong Sohn,Chaoyi Chen,Jian Yang,Xudong Liu,Yuanpei Lan,Wei Zhang,Qin Wang,Li Liu
The objective of this work was to clearly elucidate the interactions on Mn-Ce interface and understand how they affect low temperature selective catalytic reduction (SCR) for NO x removal. In this work, three Mn-Ce catalysts in similar particle size and morphology with different Mn-Ce interface areas were prepared. MnO 2 @CeO 2 -F had the tightest and largest amount of Mn-Ce interfaces compared with MnO 2 @CeO 2 -P and MnO 2 -CeO 2 -M, and also exhibited the highest NO conversion degree at 100–150 °C as well as the strongest activity of Mn species and lowest generation of N 2 O. The TG-DTG, XPS and electrochemical impedance spectroscopy results proved the redox of Ce 4+ + Mn 3+ ↔ Ce 3+ + Mn 4+ on the Mn-Ce interface, and MnO 2 @CeO 2 -F had the highest Mn 4+ , Ce 3+ , O α concentrations. The results of the study on the redox reactions during the NH 3 -SCR process provided powerful evidence of the Mn 4+ /Mn 3+ and Ce 3+ /Ce 4+ recycles that are important for low temperature NH 3 -SCR process. Moreover, the Mn-Ce interface was directly proved to benefit the surface acid sites, redox ability, and activity of the adsorbed intermediates. Both the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction mechanisms were observed in the SCR reaction with prepared Mn-Ce materials, where “fast SCR” can be observed with MnO 2 @CeO 2 -F. Moreover, the Mn-Ce interface also lowers the activation energy of the low-temperature SCR process, with MnO 2 @CeO 2 -F having the lowest activation energy. The results from this work offered powerful evidences for the interactions of Mn/Ce redox at the Mn-Ce interface and elucidated clear understanding of the effects of Mn-Ce redox on low-temperature SCR process, which is expected to promote the NO x removal process.
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
CATALYSIS TODAY
·
2019
·
IF 4.888
Shuohan Yu,Yiyang Lu,Fei Gao,Lin Dong
In this work, TiO 2 nano-octahedron and nano-rods were successfully synthesized, and Cu oxides were loaded on them. Structures of CuO/TiO 2 catalysts were studied by XRD, TEM, and Raman techniques. It was founded that TiO 2 nano-octahedron and nano-rods dominantly exposed (101) and (100) facets of TiO 2 , respectively. Cu cations located in tetrahedral vacant sites on (101) facet of TiO 2 and coordinated with 4 neighbor oxygen, whereas it located in octahedral vacant sites on (100) facet of TiO 2 and coordinated with 6 neighbor oxygen, which resulted in redox cycle Cu 2+ +Ti 3+ ⟵→Cu + +Ti 4+ and more acid sites on surface of CuO/TiO 2 nano-octahedron, and thus the enhanced NH 3 -SCR performance.
✓ 已验证
DOI
高影响因子
FUEL
·
2023
·
IF 7.4
Tingman Zhao,Bo Feng,Jiada Du,Shengdao Shan,Yun Shi
Low-temperature NH 3 -SCR of NO x technology was recognized as a promising way to control NO x emissions from industrial kilns at low temperatures. Except for SO 2 and H 2 O, lots of CO 2 exist in the flue gas of industrial kilns. However, there are few researches on the effects of CO 2 on the low-temperature NH 3 -SCR activity. To investigate the effects of CO 2 on the low-temperature NH 3 -SCR performance and mechanism of CeO x -biochar catalyst, a series of experiments employed. The results showed that the presence of CO 2 had an obvious inhibitory effect on the NH 3 -SCR performance of CeO x -biochar 0.6 at 150 °C. There was competitive adsorption between CO 2 and NO on the surface of CeO x -biochar 0.6 . CO 2 was mainly adsorbed on CeO 2 , which hindered the oxidation of NO and the adsorption of NO x on the catalyst surface. Meanwhile, although the presence of CO 2 could improve NH 3 adsorption capacity of CeO x -biochar 0.6 due to the formation of NH 4 HCO 3 and (NH 4 ) 2 CO 3 , the existence of carbonates and bicarbonates blocked the formation of active intermediates NH 4 NO 2 and NH 2 NO for NH 3 -SCR reaction. As a result, the NO x conversion of CeO x -biochar 0.6 was dropped from 96.9% to 40.8% at 200 °C. In view of the bicarbonate and carbonate species was unstable at high temperatures, the inhibitory effect of CO 2 on NH 3 -SCR reaction was gradually weakened with the increase of reaction temperature. The NH 3 -SCR activity of CeO x -biochar 0.6 was seldom affected by CO 2 at 300 °C. Finally, a CO 2 poisoning mechanism for NO x removal by NH 3 -SCR at low temperature was proposed.
✓ 已验证
产品关联
DOI
高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
·
2021
·
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
·
材料科学
✓ 已验证
DOI
高影响因子
JOURNAL OF HAZARDOUS MATERIALS
·
2019
·
IF 7.65
Guangpeng Yang,Xuesen Du,Jingyu Ran,Xiangmin Wang,Yanrong Chen,Li Zhang,Vladislav Rac,Vesna Rakic,John Crittenden
SCR activity of Cu-SAPO-34 catalyst was reduced by alkali metal ions. The alkali metals ions (Li + , Na + and K + ) have shown irregular influences on Cu-SAPO-34. The order of poisoning strengths under 400 °C was found to be: Na + > K + > Li + , which is not consistent with the basicities of their corresponding metals. Experimental results and calculations showed that the alkali metal ions readily replace H + and Cu 2+ /Cu + ions. These exchanges result in the loss of Brønsted acid sites and migration of isolated Cu 2+ ions in Cu-SAPO-34, which decrease the NH 3 -SCR activity. Both the basicity and ion diameter will affect the exchanging behavior of an alkali ion. Na + and Li + ions will influence both H + and Cu 2+ /Cu + ions but K + ions only preferably replace the H + . We hypothesize that K + cannot enter into a small ring (6-membered ring) to replace a Cu 2+ /Cu + ion because of its large ion diameter. The displaced Cu 2+ /Cu + ions will transfer to adjacent unbonded Al site to form a CuAlO 2 species.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
Journal of Physical Chemistry C
·
2015
·
IF 4.772
Weiyuan Yao,Yue Liu,Xiaoqiang Wang,Xiaole Weng,Haiqiang Wang,Zhongbiao Wu
In this paper, a sol–gel made Ce–O–P catalyst (referred to as Ce–O–P-SG) was employed for selective catalytic reduction (SCR) of NOx with NH3, which was directly compared with two other Ce–O–P samples as synthesized via hydrothermal and coprecipitation routes (referred to as Ce–O–P-HT and Ce–O–P-CP, respectively). Experimental results revealed that the Ce–O–P-SG catalyst yielded a more than 90% NO conversion at 200 °C in the presence of 10 vol % H2O, whereas Ce–O–P-HT and Ce–O–P-CP catalysts only showed 50% and 20% NO conversions under the same conditions, respectively. After subjected to a series of characterization technologies (e.g., XRD, BET-BJH, XPS, NH3-TPD, py-IR, and H2-TPR), it was found that more enriched surface Ce(4+) species were formed except for the two main CePO4 phases (monazite and rhabdophane phases) of the Ce–O–P-SG catalyst compared to the other two samples, resulting in the increase of surficial active oxygen ions content. This could lead to an enhancement in surface acidity and redox capacity of the Ce–O–P-SG catalyst, effectively promoting the NH3–SCR activity of the catalyst. Further analyses on SO2 and H2O tolerance revealed that the Ce–O–P-SG possessed a higher sulfur resistance than the other two samples, which could be attributed to the SO2 trapping effect by the abundant active oxygen species over Ce–O–P-SG 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
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
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
危险品化学品经营许可证（带存储）