Catalysts
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2020
·Vol. 10
·期 3
·311
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IF 3.52
Jing Shao,Shuyuan Cheng,Zhaoxu Li,Bichun Huang
A ZSM-5 zeolite with a hierarchical pore structure was synthesized by the desilication-recrystallization method using tetraethyl ammonium hydroxide (TEAOH) and cetyltrimethylammonium bromide (CTAB) as the desilication and structure-directing agents, respectively. The MnOx/ZSM-5 catalyst was synthesized by the ethanol dispersion method and applied for the low-temperature selective catalytic reduction of NOxwith NH3. The results showed that NOxconversion of the hierarchical MnOx/ZSM-5 catalyst could reach 100% at about 120 °C and could be maintained in the temperature range of 120–240 °C with N2selectivity over 90%. Furthermore, the hierarchical MnOx/ZSM-5catalyst presented better SO2resistance performance than the traditional catalyst in the presence of 100 ppm SO2at 120 °C. XRD, SEM, TEM, XPS, BET, NH3-TPD, and TG were applied to characterize the structural properties of the MnOx/ZSM-5 catalysts. These results showed that the MnOx/ZSM-5 catalyst had micropores (0.78 nm) and mesopores (3.2 nm) leading to a larger specific surface area, which improved the mass transfer of reactants and products while reducing the formation of sulfates. The better catalytic performance over hierarchical MnOx/ZSM-5 catalyst could be attributed to the higher concentration of Mn4+and chemisorbed oxygen species and higher surface acidity. The improved SO2resistance was related to the catalyst’s hierarchical pore structure.Keywords:hierarchical pore structure;MnOx/ZSM-5;NH3-SCR;SO2resistance
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
FUEL
·
2017
·
IF 4.601
Dongjing Liu,Weiguo Zhou,Jiang Wu
CuO-based and MnO x -based sorbents modified with Ce and La using sol-gel method, were employed for elemental mercury removal at 120–240 °C. The Hg 0 removal activity of Mn 2 O 3 /ZSM-5 can be significantly enhanced by doping 50 at.% Ce or 10 at.% La, the Hg 0 removal efficiency increased by 94% and 71%, respectively. The Hg 0 removal ability of CuO/ZSM-5 subtly improved by addition of 50 at.% Ce or 10 at.% La, the Hg 0 removal efficiency ascended only by 6% and 18%, respectively. The XPS results revealed that Hg 0 transformed to HgO, and CuO (or Mn 2 O 3 ) was reduced to Cu 2 O (or Mn 3 O 4 ), which is in agreement with Mars-Maessen mechanism.
研究领域:
环境科学
·
材料科学
✓ 已验证
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2015
·
IF 4.321
Dongjing Liu,Weiguo Zhou,Jiang Wu
x Ce y Mn/ZSM-5 sorbents were prepared using sol–gel method and employed for H 2 S removal in the temperature range of 600–800 °C. The sorbents exhibited high performance in sulfur removal due to the cooperative effect of CeO 2 and MnO x . The presence of H 2 was unfavorable for sulfidation and obviously shortened the breakthrough time and reduced the sulfur capacity. However, the existence of CO had little impact on the sulfur-removal performance. The characterization results revealed that the ZSM-5 structure remained intact during preparation and sulfidation process. And active species, such as CeO 2 and Mn 2 O 3 , were well dispersed on ZSM-5, which would suppress the mechanical disintegration and improve the thermal stability of x Ce y Mn/ZSM-5.
研究领域:
环境催化
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能源化学工程
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材料科学
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无机功能材料
·
气体净化技术
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2022
·
IF 5.723
Lin-Cong He,Xu-Fang Wang,Chu-Feng Liu,Bei Li,Meng-Fei Luo,Jian Chen
An efficient MnO x /CeO 2 /ZSM-5 catalyst was developed for selective oxidation of diethylamine (DEA) with high N 2 selectivity in a wide temperature window ( Δ T = 140 °C), owing to the existence of oxidation and selective catalytic reduction (SCR) active sites. MnO x species prefer to locate on the surface of CeO 2 compared to ZSM-5, and the presence of CeO 2 is beneficial to form more Mn 4+ species, the active sites for oxidation reaction. The mechanistic investigation suggests that internal SCR of NO x generated from the over-oxidized DEA is the crucial pathway for N 2 generation. The high SCR activity of the MnO x /CeO 2 /ZSM-5 catalyst in oxidation conditions is mainly attributed to the synergistic catalysis of Mn 4+ species and acid sites of ZSM-5, the active sites for SCR reaction. Thus, it has been clearly clarified that addition of CeO 2 and its addition sequence could modulate the surface active sites of MnO x /ZSM-5 catalyst for the selective catalytic oxidation of DEA.
研究领域:
环境科学
·
催化化学
✓ 已验证
DOI
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
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
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