Journal of Physical Chemistry C
·
2024
·
IF 3.3
Fumei Wang,Qi Cai,Xinhua He,Boxiong Shen,Leila Negahdar,Shuo Feng,Andrew M. Beale
Cu/SAPO-34 catalysts have been widely used for the reduction of NOx from diesel exhaust by ammonia-selective catalytic reduction (SCR). Sulfur poisoning remains a challenge for Cu/SAPO-34 catalysts in NH3–SCR, restricting its application. In this study, Cu/SAPO-34 samples containing a mixture of Cu species comprising isolated Cu2+ located in the 6MR, Cu(OH)+ in 8MR, CuO clusters/nanoparticles, and Cu+ species were prepared. The Cu speciation during SO2 and hydrothermal aging of Cu/SAPO-34 SCR catalysts was subsequently studied. While hydrothermal aging had little effect on catalytic activity, the sulfur-aged sample exhibited deterioration in NH3–SCR activity over the temperature range of 100–575 °C. The breakage and collapse of the zeotype framework and chemical deactivation of the Cu/SAPO-34 catalyst after exposure to SO2 and H2O took place. A combination of X-ray photoelectron spectroscopy (XPS) and TGA-DT-DSC revealed the presence of ammonium bisulfate, copper bisulfate/sulfate, aluminum sulfate, and sulfuric acid after SO2 and H2O copoisoning under SCR conditions. Furthermore, Cu(OH)+ tended to migrate to form isolated Cu2+ and Cu+, as well as agglomerate to form CuO particles. Density functional theory (DFT) calculations revealed that SO2 and O2 could readily be absorbed by CuO particles to form stable copper bisulfate/sulfate species with the following order of preference: CuO > Cu+ > Cu2+ > Cu(OH)+. In contrast, Cu(OH)+ was less prone to be poisoned by easily releasing SO3 than other Cu species sites.
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高影响因子
INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES
·
2024
·
IF 7.7
Qiuyu Zeng,Yifan Wang,Ansar Javeed,Fengyun Chen,Jiaxing Li,Yating Guan,Baiyu Chen,Bingnan Han
To address the issue of food spoilage causing health and economic loss, we developed a pH/NH 3 dual sensitive hydrogel based on polyvinyl alcohol/chitosan (PVA/CS) containing chitosan-phenol red (CP). The CP was synthesized via Mannich reaction and immobilized it in PVA/CS hydrogel through freezing/thawing method to prepare the final PVA/CS/CP hydrogel. The synthesis of CP was confirmed by 1 H NMR, FT–IR, XRD, UV–vis, and XPS. The characteristics of hydrogel were evaluated by FT–IR, XRD, SEM, mechanical properties, thermal stability, leaching, and color stability tests. The PVA/CS/CP hydrogel showed distinctly different color at various pH and NH 3 vapor levels (yellow to purple). The hydrogel exhibited obvious color changes (ΔE = 46.95) in response to shrimp spoilage, stored at 4 °C. It showed positive and strong correlation between the ΔE values of the indicator hydrogel and total volatile basic nitrogen (TVB-N) as (R 2 = 0.9573) and with pH as (R 2 = 0.8686), respectively. These results clearly show that the PVA/CS/CP hydrogel could be applied for naked-eye real-time monitoring of seafood freshness in intelligent packaging.
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PubMed
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2025
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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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高影响因子
Molecular Catalysis
·
2017
·
IF 0
Peng Sun,Rui-tang Guo,Shu-ming Liu,Shu-xian Wang,Wei-guo Pan,Ming-yuan Li,Shuai-wei Liu,Jian Liu,Xiao Sun
CeSmOx mixed oxide catalysts supported on TiO 2 prepared by coprecipitation method were used for selective catalytic reduction of NOx with NH 3 . The results showed that the addition of Sm could effectively enhance the low-temperature SCR activity and SO 2 /H 2 O resistance of Ce/TiO 2 catalyst, and the appropriate mole ratio of Sm to Ce was 0.3. Characterization results indicated that the introduction of Sm could promote the formation of Ce 3+ and chemisorbed oxygen species on catalyst surface, which was favorable to the generation of NO 2 . Moreover, the doping of Sm could also promote the adsorption of NH 3 and NOx species on Ce/TiO 2 catalyst. The results of in situ DRIFT study revealed that the NH 3 -SCR reaction over CeSm/TiO 2 -0.3 catalyst was mainly controlled by the Langmuir−Hinshelwood mechanism in the low temperature range (<200 °C). Thereafter, the promoted NO oxidation and the enhanced NH 3 adsorption should play a major role for the excellent low-temperature SCR performance of CeSm/TiO 2 -0.3 catalyst.
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MOLECULES
·
2026
·Vol. 31
·期 16
·2775
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IF 5.1
Binyu Wang,Cong Feng,Huan Liu
To clarify the role of metal dopants in low-temperature NH3-SCR of NO, FeMnTiOxcatalysts were synthesized by coprecipitation and separately modified with Ce, Co, or W. The catalysts were evaluated for NO conversion, separate O2/H2O switching response and dry-feed time-on-stream stability and characterized by XRD, SEM, N2adsorption–desorption, XPS, H2-TPR and NH3-TPD. Ce doping at Ce/Mn = 0.3 suppressed TiO2crystallization, increased the BET surface area from 136 to 231 m2g−1and the pore volume from 0.19 to 0.58 cm3g−1, raised the Mn4+/Mn3+ratio from 0.70 to 1.25, and increased the medium-strong-acid relative peak area from 555.4 to 1293.2 a.u. FeMnCe0.3TiOxmaintained at least 90% NO conversion from 140 to 360 °C, gave 75% conversion at 400 °C, and averaged 97.4% during a 40 h dry-feed test at 350 °C. The results show that the superior Ce-modified catalyst arises from the combined regulation of texture, surface redox balance and acidity.
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高影响因子
JOURNAL OF CATALYSIS
·
2025
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IF 6.5
Yanfei Liu,Yanbo Pu,Chun Du,Jie Xu,Yaohui Dun,Chengxiong Wang,Yunkun Zhao,Jun Huang,Bin Shan,Rong Chen
Selective catalytic oxidation of ammonia (NH 3 -SCO) to N 2 is crucial for abating residual NH 3 emissions, but existing catalysts struggle to combine low-temperature activity with high N 2 selectivity due to competitive Pt-NO interactions. Here we design a tandem confinement catalyst by depositing sub-nanometer Pt clusters (∼0.72 nm) inside the supercages of a Cu-exchanged USY zeolite via atomic layer deposition (ALD), creating intimately paired Pt–Cu active sites. This confined Pt/Cu-USY ALD catalyst achieves >90 % NH 3 conversion and >90 % N 2 selectivity across an exceptionally broad 170-300°C window under simulated exhaust conditions, surpassing all previously reported Pt-based NH 3 -SCO catalysts. The simultaneously enhanced low-temperature activity and high-temperature N 2 selectivity of the Pt/Cu-USY ALD catalyst can be attributed to the spatial confinement of Pt clusters within the Cu-USY framework, which leads to an expanded NO desorption window (150–350 °C). Detailed in situ studies further reveal that N 2 O 4 species preferentially serve as NO storage intermediates on the Pt/Cu-USY ALD catalyst surface at low temperatures, exhibiting significantly lower formation barriers compared to free nitrates, which dominate as intermediates in conventional Pt–Cu systems. This effectively mitigates free nitrate–induced site poisoning and overcomes the typical activity–selectivity trade-offs observed in conventional Pt–Cu dual-site catalysts.
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高影响因子
JOURNAL OF THE ENERGY INSTITUTE
·
2022
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IF 6.47
Longyi Xue,Ninghan Wei,Cheng Zhao,Xiaomei Hu,Junge Yun,Zimo Chen,Zhiyi Deng,Zhihang Chen
CeO 2 as selective catalytic reduction (SCR) catalyst has attracted wide attention due to its abundant surface acidity and excellent oxygen storage/release capacity. However, its further implication was hindered owing to insufficient catalytic activity and SO 2 resistance. Novel Cr doped CeO x catalysts were synthesized by solid phase method and used for NH 3 -SCR of NO x at middle-low temperature. The effect of Cr addition on the SCR performance and physicochemical properties of CeO 2 catalyst was investigated by activity test and characterizations. Among the tested catalysts, Cr(0.4)-CeO x catalyst exhibited excellent NO x removal efficiency, with >90% NO conversion within 180–300 °C, 100% NO conversion at 220 °C and outstanding SO 2 resistance at 240 °C under 100 or 600 ppm SO 2 . The characterizations results revealed that Cr modified CrCeO x catalyst could effectively increase BET surface area, pore volume, surface acidity and redox capacity. In situ DRIFTS indicated that SCR reactions over Cr(0.4)-CeO x catalyst followed Eley-Rideal mechanism and active –NH 2 was the major intermediate species. After sulfuration, Cr(0.4)-CeO x still exhibited excellent SCR activity due to the increase of Cr 6+ , Ce 3+ and O α concentration and the formation of Cr–O–Ce bond, new Brønsted acid site and more crystallized Cr 2 O 3 .
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高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Yang Gao,Xiaodong Wu,Rui Ran,Zhichun Si,Ziran Ma,Baodong Wang,Duan Weng
Monometallic (V/TiO 2 and Mo/TiO 2 ) and bimetallic (V-Mo/TiO 2 ) catalysts were prepared for selective catalytic reduction (SCR) of NO x with NH 3 at low temperatures (100–300 °C). The effect of MoO x on the dispersion of vanadia with different V 2 O 5 loadings was investigated on the basis of X-ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP-OES), N 2 adsorption–desorption, Raman spectroscopy, ultraviolet–visible (UV–Vis) spectroscopy, X-ray photoelectron spectroscopy (XPS), H 2 temperature-programmed reduction (H 2 -TPR) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). As the molybdenum precursor, NH 4 Mo 7 O 24 increased the solution acidity and promoted polymerization of VO x in liquid phase. At a low vanadia loading, polymerization of VO x , the adsorption rate of NH 3 and transformation of active intermediate species NH 2 were enhanced by adding MoO x , while at a high vanadia loading, the steric hindrance became dominant leading to the formation of crystalline V 2 O 5 and MoO 3 and caused decline in SCR activity.
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高影响因子
Catalysts
·
2021
·Vol. 11
·期 3
·324
·
IF 4.146
Jinkun Guan,Lusha Zhou,Weiquan Li,Die Hu,Jie Wen,Bichun Huang
SO2poisoning is a great challenge for the practical application of Mn-based catalysts in low-temperature selective catalytic reduction (SCR) reactions of NOxwith NH3. A series of Gadolinium (Gd)-modified MnOx/ZSM-5 catalysts were synthesized via a citric acid–ethanol dispersion method and evaluated by low-temperature NH3-SCR. Among them, the GdMn/Z-0.3 catalyst with the molar ratio of Gd/Mn of 0.3 presented the highest catalytic activity, in which a 100% NO conversion could be obtained in the temperature range of 120–240 °C. Furthermore, GdMn/Z-0.3 exhibited good SO2resistance compared with Mn/Z in the presence of 100 ppm SO2. The results of Brunauer–Emmett–Teller (BET), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction of H2(H2-TPR) and temperature-programmed desorption of NH3(NH3-TPD) illustrated that such catalytic performance was mainly caused by large surface area, abundant Mn4+and surface chemisorbed oxygen species, strong reducibility and the suitable acidity of the catalyst. The in situ diffuse reflectance infrared Fourier transform spectra (DRIFTS) results revealed that the addition of Gd greatly inhibited the reaction between the SO2and MnOxactive sites to form bulk manganese sulfate, thus contributing to high SO2resistance. Moreover, in situ DRIFTS experiments also shed light on the mechanism of low-temperature SCR reactions over Mn/Z and GdMn/Z-0.3, which both followed the Langmuir–Hinshelwood (L–H) and Eley–Rideal (E–R) mechanism.Keywords:SO2poisoning;low temperature;NH3-SCR;in situ DRIFTS
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高影响因子
SCIENCE OF THE TOTAL ENVIRONMENT
·
2019
·
IF 5.589
Bing Liu,Xiaochen Xu,Yuan Xue,Lifen Liu,Fenglin Yang
An integrated method of simultaneous desulfurization and denitrification from flue gas by catalytic ozonation combined with NH 3 /(NH 4 ) 2 S 2 O 8 absorption was developed for the first time. It consisted of two parts: (1) the catalytic ozonation of NO over FeO x /SAPO-34 to study the effects of the various influencing factors, and (2) the absorption–oxidation of NO x and SO 2 induced by ozone combined with a NH 3 /(NH 4 ) 2 S 2 O 8 solution in a bubble column reactor. In Part 1, results showed that under the optimal condition of a molar ratio of 0.5 for O 3 /NO, a residence time of 3 s, a water vapor volume fraction of 4%, a NO initial concentration of 536 mg/m 3 , and a SO 2 initial concentration of 343 mg/m 3 , the oxidation rate of NO was 55%. The characterizations of poisoned catalyst are briefly discussed. In Part 2, as the gas passed sequentially through the ozonizing reactor and the absorber (NH 3 /(NH 4 ) 2 S 2 O 8 solution of 0.8% ammonia and 0.2 mol/L (NH 4 ) 2 S 2 O 8 ), a NO conversion rate of approximately 92.6% and SO 2 conversion rate of 100% were obtained. The pH of the NH 3 /(NH 4 ) 2 S 2 O 8 solution had a significant impact on the NO conversion. According to the analysis of the composition of products under different pHs, a mechanism of desulfurization and denitrification based on NH 3 /(NH 4 ) 2 S 2 O 8 solutions was proposed. The reaction product as a compound fertilizer contained up to 24.5% nitrogen.
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高影响因子
APPLIED SURFACE SCIENCE
·
2023
·
IF 6.7
Jie Yang,Xinyu Li,Yujia Xu,Lin Chen,Shan Wang,Shan Ren,Junjiang Zhu
Zeolite X was used as support of copper catalyst (Cu/X) for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH 3 ). Modulated excitation in situ/ operando infrared (IR) spectroscopy and phase-sensitive detection (PSD) were applied to study the reaction intermediates that formed on the Cu/X during transient experiments. Changing the gas concentration to periodically create unsteady conditions enabled the selective extraction of the dynamic species that were directly involved in the reaction. The IR results showed that only Lewis acid sites (L X ) existed on zeolite X,and Brønsted acid sites (B) and extra Lewis acid sites (L Cu ) were generated after Cu loading. The transient experiment results indicated that the SCR reactions on Cu/X obeys the Eley − Rideal (E − R) mechanism, in which NH 3 is first adsorbed on the L X and L Cu sites (L X –NH 3 , L Cu –NH 3 ) and then moved to the B sites (B–NH 3 ), where it reacted with gas-phase NO to form NH 2 NO intermediate, which finally decomposed into N 2 and H 2 O. Moreover, it is found that the NH 3 adsorbed on L Cu and B sites exhibits stronger reactivity than that on the L X sites.
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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.
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