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.
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CHINESE JOURNAL OF CHEMICAL ENGINEERING
·
2021
·
IF 3.171
Xin Yong,Hong Chen,Huawang Zhao,Miao Wei,Yingnan Zhao,Yongdan Li
The effects of SO 2 on an one-pot synthesized Cu-SSZ-13 catalyst for selective reduction of NO x by NH 3 were examined. The addition of SO 2 inhibited NO x conversion significantly below 300 °C, while no effect on NO x conversion was observed above 300 °C. TGA, TPD , and XPS results showed that the deactivation was caused by the formation of (NH 4 ) 2 SO 4 , SO 2 chemisorption on the isolated Cu 2+ ion sites, as well as the formation of CuSO 4 -like species. Among them, the site-blocking effect of (NH 4 ) 2 SO 4 on Cu 2+ was the primary reason for deactivation. Fortunately, 89% of deNO x activity of the poisoned catalyst was recovered after thermal treatment at 500 °C in air, where (NH 4 ) 2 SO 4 was completely decomposed. The activity was further recovered with regeneration temperature increasing to 600 °C, removing the adsorbed SO 2 on the Cu 2+ sites. The regeneration at 600 °C could not recover the activity completely, because of the high stability of CuSO 4 -like species.
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RSC Advances
·
2021
·Vol. 11
·期 37
·22780-22788
·
IF 3.361
Xiaoyi Sun,Qingjie Liu,Shuai Liu,Xintang Zhang,Shanshan Liu
A series of MOx–Cr2O3–La2O3/TiO2–N (M = Cu, Fe, Ce) catalysts with nitrogen doping were prepared via the impregnation method. Comparing the low-temperature NH3-SCR activity of the catalysts, CeCrLa/Ti–N (xCeO2–yCr2O3–zLa2O3/TiO2–N) exhibited the best catalytic performance (NO conversion approaching 100% at 220–460 °C). The physico-chemical properties of the catalysts were characterized by XRD, BET, SEM, XPS, H2-TPR, NH3-TPD and in situ DRIFTS. From the XRD and SEM results, N doping affects the crystalline growth of anatase TiO2 and MOx (M = Cu, Fe, Ce, Cr, La) which were well dispersed over the support. Moreover, the doping of N promotes the increase of the Cr6+/Cr ratio and Ce3+/Ce ratio, and the surface chemical adsorption oxygen content, which suggested the improvement of the redox properties of the catalyst. And the surface acid content of the catalyst increased with the doping of N, which is related to CeCrLa/TiO2–N having the best catalytic activity at high temperature. Therefore, the CeCrLa/TiO2–N catalyst exhibited the best NH3-SCR performance and the redox performance of the catalysts is the main factor affecting their activity. Furthermore, in situ DRIFTS analysis indicates that Lewis-acid sites are the main adsorption sites for ammonia onto CeCrLa/TiO2–N and the catalyst mainly follows the L–H mechanism.
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JOURNAL OF HAZARDOUS MATERIALS
·
2019
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IF 7.65
Hong Sun,Zhigang Liu,Ying Wang,Xie Quan,Guozhi Zhao
A novel MnOx@MIL-125(Ti) catalyst was constructed for the selective catalytic reduction (SCR) of NOx with NH 3 , in which MIL-125(Ti), a kind of metal-organic frameworks (MOFs), was used as the support because of the structural feature, large surface area and high thermal stability. The SCR results showed that MnOx@MIL-125(Ti) exhibited high deNOx ability and N 2 selectivity in a wide operating temperature range. Moreover, it exhibited better SO 2 resistance than MnOx/TiO 2 (P25). Characterization results revealed that MIL-125(Ti) had resulted in a high dispersion of MnOx and a strong metal-support interaction for MnOx@MIL-125(Ti), which could promote the formation of the abundant Mn 4+ and surface chemical oxygen, facilitating the activation of the reactants. In situ DRIFTS results suggested that NH 3 -SCR over MnOx@MIL-125(Ti) followed both Langmuir-Hinshelwood (L-H) and Eley-Rideal (E-R) mechanism. In addition, NO − species were proved to be the important intermediates which were involved in SCR reaction.
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APPLIED CATALYSIS B-ENVIRONMENTAL
·
2014
·
IF 6.007
Yue Liu,Weiyuan Yao,Xiaoli Cao,Xiaole Weng,Yan Wang,Haiqiang Wang,Zhongbiao Wu
This paper reported the feasibility of a supercritical water synthesis route (referred as CHFS) in the application of selective catalytic reduction (SCR) of NO with NH 3 . A series of well-reported Ce x TiO 2 SCR catalysts were synthesized and then subjected to a range of characterizations (e.g. XRD, XPS, H 2 -TPR, HADDF, etc.). Experimental results revealed that the unusual and rapid crystallizing environment of the CHFS route had resulted in a highly dispersed CeO 2 and a strong metal-support interaction (SMSI) for Ce x TiO 2 catalysts, which promoted the enriched surface oxygen vacancies and facilitated the formation of NO 2 and nitrite species over the catalyst surface, effectively enhancing their SCR performances. Amongst the developed Ce x TiO 2 catalysts, Ce 0.25 TiO 2 revealed the highest SCR activity with more than 90% NO conversion being achieved in a broad temperature range of 240–440 °C. Such broad temperature window was proven due to the SMSI, which lowered the NH 3 oxidation ability of CeO 2 , retaining the effective utilization of NH 3 throughout the SCR process. The work conducted herein demonstrates the feasibility of the CHFS route in the syntheses of SMSI catalysts for SCR application and also explores the SCR reaction mechanism over the well-reported Ce x TiO 2 catalysts. We expected that this work could shed some lights on the development of feasible preparative routes for the syntheses of advanced SMSI catalysts for SCR application.
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Journal of Environmental Chemical Engineering
·
2024
·
IF 7.4
Yanli Zhang,Jian Li,Jianyu Cai,Shuangye Li,Xing Fan,Liyun Song,Ruixue Guo,Jiasheng Liu
In this study, a series of γ-Fe 2 O 3 -modified V 2 O 5 -MoO 3 /TiO 2 (VMT) catalysts was prepared by wet impregnation method. The γ-Fe 2 O 3 -modified catalysts exhibited excellent catalytic performance, and 1.25 wt% γ-Fe 2 O 3 content improved the deNO x efficiency at 150 °C from 54% (unmodified VMT catalyst) to 84% (modified catalyst). BET, XRD, XPS, NH 3 -TPD, H 2 -TPR, and in situ DRIFTs were employed to characterize the physicochemical properties and reaction mechanisms of the catalysts. The introduction of γ-Fe 2 O 3 increased the V 5+ /V 4+ ratio, surface chemisorbed oxygen content, redox ability, and a number of acid sites in the prepared catalysts. XPS confirmed the addition of γ-Fe 2 O 3 introduced new charge transfer pathways (Fe 3+ /Fe 2+ ↔ V 5+ /V 4+ ). In situ DRIFTs suggested that the addition of γ-Fe 2 O 3 to the catalyst significantly increased the adsorption capacity of catalyst for NH 3 and NO x , while also exerting a strong activating effect on the adsorbed NH 3 . Furthermore, selective catalytic reduction over the VMT and 5PEG@1.25Fe-VMT catalysts followed the Eley-Rideal (E-R) mechanism. At temperatures above 200 °C, the 5PEG@1.25Fe-VMT catalyst also followed the Langmuir-Hinshelwood (L-H) mechanism.
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CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Chunran Zhao,Chenrui Wang,Xujie Ren,Shude Yuan,Leihong Zhao,Lvchao Zhuang,Botao Teng,Ying Wu,Yiming He
Fabricating heterophase junctions proves to be an efficient strategy for achieving efficient charge separation and enhancing the catalytic activity of photocatalysts. Surprisingly, this approach is rarely utilized in the field of piezocatalysis. In this work, a novel ZnSnO 3 heterophase junction catalyst was fabricated by combining rhombohedral (R-ZnSnO 3 ) and orthorhombic (O-ZnSnO 3 ) phases for efficient piezo and piezo-photocatalytic RhB degradation and N 2 fixation. The piezocatalytic RhB degradation rates of ZnSnO 3 heterophase catalysts are 5.6 and 3.6 times higher than those of O-ZnSnO 3 and R-ZnSnO 3 , respectively, with similar enhancements observed in piezocatalytic N 2 fixation. The coupling of R-ZnSnO 3 and O-ZnSnO 3 does not increase the piezoelectric properties; however, an S-scheme structure formed at the interface. Under the combined effects of band bending, interface electric fields, and Coulomb attraction, electrons and holes migrate and achieve effective spatial separation. This result supports the energy band theory over the induction charge theory, contributing to the ongoing debate in piezocatalytic mechanisms. Electrochemical analyses and piezo-photocatalytic tests further indicate that ZnSnO 3 heterophase junctions exhibit a synergistic effect between piezocatalysis and photocatalysis. This synergy can be attributed to the complementary effects of photoinduced carrier generation and piezoelectric field-assisted carrier separation. Hydroxyl radicals, superoxide radicals, and holes serve as the primary active species responsible for piezocatalytic RhB degradation through a mechanism similar to photocatalysis. Theoretical calculations reveal that the Sn site on the surface of O-ZnSnO 3 acts as the active site within the ZnSnO 3 heterophase junction, providing valuable insights for future catalyst development. This work offers a deeper understanding of the synergistic mechanisms in piezo-photocatalysis, presenting a promising route for efficient environmental and energy applications.
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INORGANIC CHEMISTRY COMMUNICATIONS
·
2025
·
IF 5.4
Jian Gao,Xinrui Dai,Zhenhua Gu,Guixian Deng,Jiangyong Yuan,Kongzhai Li
Catalysts loaded with metal oxides of M (M = Mn, Co, Ce) were synthesized by deposition precipitation method using cold rolled sludge (iron oxide as the main component) as a raw material for the selective catalytic reduction of NO x by ammonia (NH 3 -SCR). Among the various formulations, the co-supported catalyst containing 5 % Mn and 5 % Co on CRS-400 exhibited exceptional SCR performance, achieving over 90 % conversion of NO x from 80 °C to 200 °C. The addition of 5 % Mn and 5 % Co as active components resulted in an increase in the specific surface area for catalytic performance and an enhancement of the redox capacity, leading to a significant improvement in catalyst activity. The catalyst’s efficient denitration performance was attributed to the synergistic interaction between Mn, Co, and Fe oxides, resulting in a catalyst with a higher proportion of adsorbed oxygen, as well as an elevated composition of Mn 4+ and Fe 2+ species. The catalyst demonstrated excellent SCR activity at low-temperatures, indicating its potential for downstream applications in soot treatment equipment. This would achieve the dual benefits of purifying the atmosphere and disposing of solid waste.
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JOURNAL OF CATALYSIS
·
2024
·
IF 6.5
Yin Che,Xuezhen Liu,Lifei Liu,Yali Du,Xia An,Xu Wu
Arranging an ammonia oxidation process after the selective catalytic reduction of NO x by NH 3 (NH 3 -SCR) system is an effective way for ensuring the DeNO x efficiency and controlling the slip ammonia. To improve operability and reduce operating costs in ammonia selective catalytic oxidation (NH 3 -SCO), developing feasible and efficient catalysts becomes meaningful. Herein, focusing on the dilemma of Ag/Al 2 O 3 catalysts in NH 3 -SCO applications, Ag/MgAlO x catalysts with different support different crystalline phase structures (5 %Ag/MgAl-LDO and 5 %Ag/MgAl 2 O 4 ) were innovatively synthesized and systematically evaluated application potential in NH 3 -SCO. Results indicated that the introduction of Mg apparently broadened reaction temperature window and catalytic performance of 5 %Ag/MgAl 2 O 4 was higher than 5 %Ag/MgAl-LDO, while the N 2 selectivity was completely opposite. The combination of series characterization and density functional theory (DFT) calculations revealed that 5 %Ag/MgAl 2 O 4 surface has more Ag 0 species with small particle size, which is favorable for ammonia adsorption and activated dehydrogenation to further promote reaction of NO x species, resulting in a higher NH 3 -SCO activity. In contrast, 5 %Ag/MgAl-LDO readily induces oxidized Ag species and Ag 0 is more inclined to be present in large particle sizes, which is more conducive to dissociation of O 2 to produce reactive O species (O*) leading to the peroxidation of ammonia to nitrate and thus, positively affects the improvement of N 2 selectivity. Model catalyst 5 %Ag/MgAl-650 (mixed-phase) was prepared by controlling the roasting conditions and exhibited excellent catalytic performance in NH 3 -SCO with almost 93 % of NH 3 oxidized at 250 °C (N 2 selectivity up to 71 %). This work could afford theoretical support for the optimization and application of catalysts with high performance at low temperatures in selective catalytic oxidation of slip ammonia.
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Science China-Chemistry
·
2026
·
IF 9.8
Zhong Fengyi,Sheng Jianping,He Ye,Du Chenyu,Ma Xiaodan,Moghadam Majid,Sun Yanjuan,Dong Fan
Under mild continuous-flow gas-solid conditions, the direct conversion of gaseous nitric oxide (NO) in flue gas to pure ammonia (NH 3 ) is hindered by the challenges of sustaining continuous proton-electron coupling and transfer. Here, we develop a PtO x -TiO 2 photocatalyst featuring ultrafine PtO x clusters that sustain continuous electron transfer via dynamic PtO x /PtO ( x−δ ) redox cycling. Upon illumination, PtO x continuously captures photogenerated electrons to form PtO ( x−δ ) and injects them into NO antibonding orbitals, while the PtO x -TiO 2 interface simultaneously drives H 2 O dissociation to provide a steady proton flux. This persistent electron-proton coupling orchestrated by PtO x /PtO ( x−δ ) cluster interface promotes exciton dissociation, interfacial charge separation, and stepwise hydrogenation of NO to NH 3 . Under continuous-flow conditions with 200 ppm NO, PtO x -TiO 2 achieves 76.0% NO conversion, 808.25 mmol m −2 h −1 NH 3 yield, and 98.1% selectivity, representing a 9.1-fold enhancement over pristine TiO 2 and representing the current best performance in the gas-solid phase NO reduction for NH 3 synthesis. In situ spectroscopy and density functional theory (DFT) calculations reveal that the exceptional activity mainly stems from the facilitated electron-proton coupled transfer via the unique role of PtO x /PtO ( x−δ ) cluster. This work establishes a practical strategy for sustainable NO abatement with green NH 3 production without separation in gas-solid systems.
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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.
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PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2025
·
IF 2.9
Yulong Deng,Jiacheng Zheng,Wenting Chen,Xu Wang,Chengliao Deng,Xiaoming Cai,Jinming Cai,Honglin Tan
NH3 selective catalytic reduction (SCR) is a promising method for NOx removal, but its low-temperature effectiveness and narrow operating window limit industrial use. This study demonstrates, through DFT calculations and experimental validation, that Fe-doped CoMn2O4 (CoFe0.1Mn1.9O4) catalysts can effectively enhance catalytic activity. Through the in-depth study of NH3-SCR, it was found that the NH3 adsorption on the catalyst surface might be significantly enhanced by the doping of Fe (Eads = −1.29 eV → −1.42 eV), and it was also further demonstrated that the NH3 had a better adsorption energy on the surface of the CoFe0.1Mn1.9O4 catalyst through the electron difference density (EDD) and partial density of states (PDOS). In addition to this, the CoFe0.1Mn1.9O4 catalyst not only reduces the first step of the dehydrogenation reaction of NH3 (Eα = 0.86 eV → 0.83 eV), but also lowers the energy barrier of the NH3-SCR (Eα = 1.11 eV → 0.86 eV). All these calculations demonstrate that Fe doping has the potential to significantly enhance catalytic performance. CoMn2O4 and Fe-doped CoMn2O4 (CoFe0.02Mn1.98O4) catalysts were synthesized using sol–gel and impregnation techniques, respectively. Through characterization and performance testing, CoFe0.02Mn1.98O4 is found to exhibit a more efficient NOx conversion (87% at 250 °C), and its N2 selectivity is also slightly improved (64%), which matches with the calculation results. In this study, a method to improve the denitrification efficiency of CoMn2O4 spinel catalysts was proposed, which provides a new idea for the development of CoMn2O4 catalysts.
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