APPLIED SURFACE SCIENCE
·
2024
·
IF 6.3
Kaiting Chen,Xinyu Han,Qian Wang,Kaijie Liu,Xiangguang Yang,Yibo Zhang
The selective catalytic reduction of NO by CO (CO-SCR) presents an economical and promising approach to mitigate emissions of NO x and CO from motor vehicles. A bimetallic Rh-Mn supported catalyst Rh-Mn/CoAlO was synthesized through the reduction of citric acid and ethylene glycol, and subsequently employed in the CO-SCR reaction. Tests assessing its catalytic performance revealed that the Rh-Mn/CoAlO catalyst displayed superior CO-SCR activity, maintaining high efficiency (≥90 % at 230 °C) and stability while simultaneously reducing the usage of noble metals. Various characterization techniques, including H 2 -TPR, NO-TPD, CO-pulse, and XPS, indicated that the Rh-Mn/CoAlO catalyst possessed enhanced dispersion of noble metals. This increased dispersion ensured optimal contact between Rh and Mn, as well as the support, fostering a synergistic interaction that facilitated electron transfer. Consequently, the catalyst’s adsorption and activation capabilities for NO were significantly improved. In situ DRIFTs studies further elucidated that the catalyst primarily followed the E-R mechanism, wherein NO is adsorbed onto the catalyst surface, and subsequently, the N and O atoms generated from pyrolysis react with CO in the gas phase. The findings of this study are anticipated to offer an effective strategy for designing catalysts with exceptional low-temperature activity and high dispersibility for the reduction of NO using CO.
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 Environmental Chemical Engineering
·
2023
·
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
·
催化化学
✓ 已验证
DOI
高影响因子
ChemNanoMat
·
2023
·Vol. 9
·期 11
·e202300407
·
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
·
环境科学
·
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF CATALYSIS
·
2023
·
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
·
环境科学
·
化学工程
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 86
·82707-82715
·
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
·
环境科学
·
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）