Journal of Environmental Chemical Engineering
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2024
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IF 7.4
Lei Wang,Xin Zhang,Yonggang Sun,Yulong Ma,Min Xu,Juan Zhang,Yingbo Zhu,Li Zhu,Song Qiao,Jing Ma,Jinpeng Wei,Feng Lin
Environmental H 2 O has a significant effect on the reaction mechanism and process of VOC oxidation, of which the intrinsic mechanism is hardly reported. Herein, a series of PtCu δ -MnO x catalysts with different strong metal-supported interactions were constructed by replacing some Pt species with Cu species. Among them, the PtCu 3 -MnO x catalyst exhibited superior catalytic performance (T 90 = 170 ℃), high water resistance, and long-term stability. Furthermore, in-situ diffuse reflectance infrared Fourier transform spectroscopy ( in-situ DRIFTs) showed that the acetone oxidation followed synergistic cooperation of the Langmuir-Hinshelwood (L-H) and Mars van Krevelen (MvK) mechanism. Acetone oxidation over PtCu 3 -MnO x occurred via the L-H mechanism producing surface acetate and formate species intermediate. Above 100 °C, adsorbed acetone (i.e., acetate and formate species) reacts with MnO x lattice oxygen according to the MvK mechanism to form CO 2 and H 2 O. When water vapor was present, the L-H mechanism was impaired, inhibiting the deep oxidation of acetone. This research provides an in-depth exploration of how water vapor impacts the reaction mechanism of acetone oxidation. It offers valuable insights for creating dependable catalysts suitable for use in various industrial settings.
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
Journal of Environmental Chemical Engineering
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2023
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IF 7.7
Chen Cai,Jiayin Chen,Wei Fu,Shuying Ning,Hao Zhou,Muhammad Kashif,Yaxin Su
The Ce-modified OMS-2 catalyst (Ce x -OMS-2) was synthesized by the hydrothermal synthesis method, after which its catalytic efficacy in the selective reduction of NO by CO was assessed. The experiments showed that Ce 0.08 -OMS-2 was capable of 100% NO conversion between 175 and 300 °C when 0.05%NO, 0.1%CO, 5%O 2 and N 2 were used as equilibrium gases, and the N 2 selectivity peaked at 93.2% at 175 °C. Additionally, Ce 0.08 -OMS-2 exhibits good sulfur resistance in the presence of 0.02% SO 2 and maintains more than 88% NO conversion at 175–275 °C. By using BET, XPS, H 2 -TPR, NH 3 -TPD, and In situ DRIFTS to characterize the catalysts, the effects of doping the active metal Ce on the physicochemical characteristics of OMS-2 catalysts were under investigation. In conclusion, the improvement of the low-temperature activity of the Ce x -OMS-2 catalyst is facilitated by lower agglomeration and crystallinity , larger specific surface area, smaller average pore size, enhanced surface oxygen vacancies, increased Mn 4+ concentration, and richer Brønsted acid. Reaction gas adsorbed species and intermediates on the catalyst surface were dynamically captured during In situ DRIFTS experiments. The CO-SCR reaction of the catalyst was found to follow the E-R mechanism below 200 ℃ and the L-H mechanism at 200–350 ℃.
研究领域:
环境科学
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催化化学
✓ 已验证
DOI
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 37
·22780-22788
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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.
研究领域:
催化
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环境科学
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材料科学
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产品关联
DOI
PubMed
高影响因子
ChemNanoMat
·
2023
·Vol. 9
·期 11
·e202300407
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IF 3.8
Xinyu Han,Mengyao Bian,Kaijie Liu,Xin Yang,Daying Zheng,Xiangguang Yang,Yibo Zhang
Graphical Schematic diagram of the dominant mechanism of NH 3 -SCR reaction on CeCu/MCM-49 catalyst before and after poisoning. The L−H mechanism was dominant before poisoning. However, after alkali metal poisoning, NO x adsorption on the catalyst is inhibited, so the E−R mechanism dominates. NO x is a common atmospheric pollutant, and NH 3 -SCR technology efficiently purifies it. CeCuO x binary-oxide nanoparticles were synthesized and loaded onto acid MCM-49 molecular sieve with a large specific surface area to increase acid sites and disperse active sites of the catalyst. The optimized 35 % CeCu/MCM-49 catalyst effectively purified over 80 % of NO x in the temperature range of 200–500 °C and demonstrated excellent resistance to alkali metals, such as K, Na, and Ca. Even after K poisoning, it still removed over 80 % of NO x in the range of 200–450 °C. Various characterization methods, including XRD, FT-IR, TEM, and N 2 isotherm adsorption-desorption tests, confirmed the structure of the catalyst remained intact after poisoning with no substance change, nor agglomeration of nanoparticles. NH 3 -TPD and H 2 -TPR confirmed that the catalyst had effective acidity and redox capacity that were not affected by alkali metals. In-situ DRIFTs showed that the catalytic reaction predominant mechanism shifted from L−H to E−R mechanism after poisoning. This study provides valuable insights into the development of high-performance Ce-based NH 3 -SCR catalysts with alkali metal resistance.
研究领域:
催化
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环境科学
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材料科学
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化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
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2023
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IF 7.3
Shan Li,Yin Che,LiFei Liu,Yali Du,Xu Wu
Understanding the effect of CuO x valence state specifically is significant for constructing high-performance Cu based oxide catalyst for low-temperature selective catalytic reduction of NO with NH 3 (NH 3 -SCR). In this work, CuO x with different valence state including Cu 2 O, Cu 2 O-CuO and CuO particles are synthetized as model catalysts, which present same variation laws in catalytic performance at 180 ℃, 210 ℃ and 240 ℃. NH 3 -SCR catalytic performance of Cu 2 O-CuO heterojunction is the best, CuO exhibits good catalytic activity, while Cu 2 O possesses excellent N 2 selectivity. Experimental results combined with density functional theory (DFT) calculations reveal that Cu 2+ favor to form monodentate nitrate and possess strong ability of activation and dehydrogenation of NH 3 . The energy barrier for the form of NH 2 * is 79.5 kJ/mol, which is much lower than that for Cu + . While Cu + is beneficial to NH 3 and NO x adsorption and the form of bidentate nitrate, which have a positive impact on improving the selectivity of N 2 . Moreover, the collaboration of Cu 2+ and Cu + facilitates the redox capability and the form of surface adsorbed oxygen species, thus the reaction progress is further promoted. The SCR reaction catalyzed by three samples are dominated mainly by Langmuir-Hinshelwood (L-H) mechanism at 180 ℃. While at 240 ℃, the reaction over Cu 2 O follows Eley-Rideal (E-R) mechanism, during which the rate-limiting step is the internal hydrogen transfer procedure (NH 2 NO*→NHNOH*). Over CuO, the reaction follows L-H mechanism, the process of atomic isomerism (NHNOH*+ *→N 2 *+H 2 O*) is the rate-determining step. The energy barriers are 136 and 146 kJ/mol, respectively. This work may supply important theoretical support for the preparation of high-performance Cu-based oxide catalysts.
研究领域:
催化
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环境科学
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化学工程
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
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2023
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IF 6.7
Guanjun Chen,Jinheng Ma,Junxuan Zhang,Ying Lin,Tong Wang,Yan Cheng,Haibo Yang,Fei Ma
Pt-based nanostructures are an indispensable component in the anodic electrocatalysts of direct methanol fuel cells (DMFCs). Unfortunately, they often suffer from severe operational durability issues, due to CO poisoning. Here, a ternary hybrid consisting of Pt nanocrystals, ultrathin nanoflower-like nickel carbonate hydroxide (NiCH) and porous carbon is designed and fabricated to overcome this issue. Owing to the abundance of defects and large surface area of the NiCH, water molecules are easily dissociated to form OH adspecies, which could assist the oxidative removal of carbonaceous poisons from nearby Pt nanoparticles by the L-H mechanism. Porous carbon offsets the poor conductivity of NiCH and accelerates charge transfer. Impressively, this hybrid electrocatalyst could maintain over 39% of the initial activity after 5000 s of stability testing, and the MOR peak current was reduced by only 25% after 8000 CV cycles. CO stripping experiments demonstrate this incredible CO tolerance. DFT calculations further elucidate that the electronic interactions between H atom from NiCH and Pt downshifts the d-band center of Pt atom and accelerates the release of CO adsorbed on its surface. This work offers a promising candidate for the design of DMFCs anodic electrocatalysts.
研究领域:
材料科学
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电化学
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催化
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能源存储与转换
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 86
·82707-82715
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IF 3.289
Wei Li,Rui-tang Guo,Shu-xian Wang,Wei-guo Pan,Qi-lin Chen,Ming-yuan Li,Peng Sun,Shu-ming Liu
A series of Mn/CeSiOx catalysts were prepared by the wet impregnation method and used for selective catalytic reduction of NO with NH3. As can be seen from the experimental results, the Mn/CeSiOx catalyst with a Ce/Si molar ratio of 2/1 showed excellent low-temperature SCR activity, high N2 selectivity and excellent SO2 and H2O tolerance. The relationship between the CeSiOx support and the SCR performance of Mn/CeSiOx (2 : 1) catalyst was investigated based on the characterization results of N2 adsorption, XRD, XPS, H2-TPR, NH3-TPD and in situ DRIFT. The strong interaction between Ce and Si resulted in the good dispersion of Mn species on the support; correspondingly, the redox ability and NH3 adsorption capacity were greatly enhanced. The results of in situ DRIFT study revealed that the NH3-SCR reactions over Mn/CeO2 and Mn/CeSiOx (2 : 1) mainly obeyed both the E–R mechanism and the L–H mechanism. Furthermore, the formation of more Mn4+ and chemisorbed oxygen greatly facilitates the oxidation of NO to NO2, as a result, promoting the low-temperature SCR performance of Mn/CeSiOx (2 : 1).
研究领域:
催化
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环境科学
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化工
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）