Scientific Reports
·
2019
·Vol. 9
·期 1
·1-14
·
IF 4.011
Dong Fang,Meng Yu,Han Weiliang,Zhao Haijun,Tang Zhicheng
Here, we synthesized a series of Cu/CeO 2 catalysts with different morphology and size, including Cu/CeO 2 nanospheres (Cu/CeO 2 -S), Cu/CeO 2 nanoparticles (Cu/CeO 2 -P), Cu/CeO 2 nanorods (Cu/CeO 2 -R) and flower-like Cu/CeO 2 microspheres (Cu/CeO 2 -F) to systematically explore the structure-activity relationship in CO oxidation. Crucially, the effect of morphology, crystal size, Ce 4+ /Ce 3+ species, oxygen vacancies derived from the removal of lattice oxygen (O latt ) species in CeO 2 and lattice defect sites on CO activity was revealed through various characterizations. It was clearly discovered that the activity of these catalysts was as follows: Cu/CeO 2 -R > Cu/CeO 2 -P > Cu/CeO 2 -S > Cu/CeO 2 -F, and the Cu/CeO 2 -R catalyst preferentially showed the best catalytic performance with a 90% conversion of CO even at 58 °C, owned the smaller particles size of CeO 2 and CuO, and exhibited the higher concentration of O latt species and oxygen vacancies. Besides, it is also verified that the Cu/CeO 2 -F sample exhibited the larger CeO 2 crystal size (17.14 nm), which led to the lower Cu dispersion and CO conversion, even at 121 °C (T 90 ). Most importantly, we discovered that the amount of surface lattice defect sites was positively related to the reaction rate of CO. Simultaneously, DFT calculation also demonstrated that the introduced oxygen vacancies in CeO 2 could accelerate the oxidation of CO by the alteration of CO adsorption energy. Therefore, the morphology, the crystal size, the content of oxygen vacancies, as well as lattice defects of Cu/CeO 2 catalyst might work together for CO oxidation reaction.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
ACS Applied Nano Materials
·
2025
·
IF 5.5
Sajid Ali,Xingwen Cha,Jinxin He,Muhammad Ubaid Ali,Muhammad Junaid Aslam,Songbo Chen,Kok Bing Tan,Guowu Zhan
Tunable electronic properties of supported Cu/CeO2 catalysts are critical for improving the active site activity in catalysis. In this contribution, we propose a surface engineering protocol that utilizes unique ascorbic acid (AA) properties to generate surface defects and modify the electronic properties of Cu–Ce catalysts. This approach relies on forming abundant (Ce3+-Ov) defective sites on the CeO2 surface synthesized with a Ce-benzene-tricarboxylate metal–organic framework (MOF) as a precursor through AA adsorption. Subsequently, Cu sites can be effectively anchored onto the generated Ce3+-Ov, exhibiting excellent electronic transfer between (Ce3+-Ov/Ce4+ ↔ Cu2+/Cu+) CuCe, resulting in highly active Cu+ with well-balanced Ce3+-Ov defects. A high fraction of Cu+ with Ce3+-Ov was dedicated to the presence of AA. The resultant Cu/AA-MOF-CeO2 catalyst demonstrated outstanding performance toward CO oxidation (90–95 °C), being far superior to that of the conventionally prepared Cu/MOF-CeO2 catalyst (110–115 °C). In-depth characterizations confirmed that the remarkable performance was considerably related to the enhanced Cu–Ce interaction, enriched Cu+ active sites, and balanced Ce3+-Ov defects. This work highlights the potential of the Cu/AA-MOF-CeO2 catalyst as a sustainable solution for low-temperature catalytic CO oxidation reaction.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ChemCatChem
·
2024
·
IF 3.8
Pengchao Ren,Zhenzhou Zhang,Tingting Hu,Zhihui Fan,Shanshan Dang,Sifan Cheng,Weifeng Tu,Yi-Fan Han
Graphical The apparent rate coefficients for CH 3 OH synthesis from CO hydrogenation are a single-valued function of the CO 2 -to-CO ratio in the contacting gas phase, because this ratio determines the extent of surface oxidation of Ce 2 O 3 to CeO 2 , the relative abundance of surface Ce 3+ , and in turn the density of Cu 0 -Ce 3+ sites pair on the working Cu/CeO 2 catalyst. This study investigated the dynamic structure of a working Cu/CeO 2 catalyst and its catalytic consequences for CH 3 OH synthesis via CO hydrogenation by kinetics, high-precise chemical titration, and a series of in situ X-ray spectroscopies. We have revealed that the apparent rate coefficients for CH 3 OH synthesis from CO hydrogenation are a single-valued function of the CO 2 -to-CO ratio in the contacting gas phase. This ratio determines the extent of surface oxidation of Ce 2 O 3 to CeO 2 , the relative abundance of surface Ce 3+ and Ce 4+ sites, and in turn, the density of Cu 0 -Ce 3+ sites pair on the working Cu/CeO 2 catalyst, although the chemical state of Cu and elemental distribution of both Cu and Ce were insensitive to the ratio. The reactivity of CH 3 OH formation and the Cu 0 -Ce 3+ sites decrease monotonously with an increase in the CO 2 -to-CO ratio. The direct connection of the reactivity and the oxidant-to-reductant ratio appears to be general for heterogeneous catalysis, for which the oxidant oxidizes metal atoms. In contrast, the reductant scavenges surface oxygen atoms, thus dictating the density of surface sites and their thermodynamic activities.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
CATALYSIS TODAY
·
2024
·
IF 5.2
Ziheng Zhen,Antai Li,Youwei Yang,Ying Hu,Jing Lv,Shouying Huang,Yue Wang,Xinbin Ma
Cu/CeO 2 catalysts have been wildly used for the hydrogenation of carbon-oxygen bonds reactions due to their excellent catalytic performance. It is widely accepted that the Cu 0 -Cu σ+ interface could be the primary active sites during the reaction, but how to form and maintain highly dispersed such species remains challenging under the reaction conditions of high temperature and H 2 partial pressure. In this work, we proposed an effective strategy to construct stable Cu 0 -Cu σ+ interface sites over the Cu/CeO 2 catalysts by in situ N 2 O-involved oxidation treatment . It was evidenced that the sequential oxidation-reduction by N 2 O and H 2 broke the grain boundaries of Cu nanoparticles and therefore facilitated the formation of the active Cu 0 -Cu σ+ sites, leading to an enhanced activity. However, a rapid deactivation was observed after this temporary enhancement due to the aggregation of copper species. We further introduced some additional cerium species during catalyst preparation. The 16Cu/CeO 2 -1Ce catalyst prepared by post-impregnation of 1 wt% cerium achieved a stable performance of 90.6% MA conversion after the N 2 O-involved oxidation treatment, which was much higher than that of 26.2% over the 16Cu/CeO 2 catalyst. It was demonstrated that the strong interaction between the formed CeO 2 and reconstructed Cu species prevented the metal sintering and increased the fraction of the Cu 0 -Cu σ+ sites. This method that combined in situ N 2 O-involved oxidation treatment and cerium modification may offer potential in engineering stable active sites for high-performance catalysts in the hydrogenation of carbon-oxygen bonds.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2025
·
IF 8.2
Liang Zhu,Yang Liu,Yanhui Gao,Ningxujin Ding,Danyu Wang,Liuliu Long,Beibei Wang,Junyu Lang,Evgeny I. Vovk,Yong Yang
The hydrogen dissociation and spillover mechanism on oxide-supported Cu catalysts play a pivotal role in the hydrogenation of carbon dioxide to methanol. This study investigates the hydrogen spillover mechanism on Cu/CeO2 catalysts using in situ spectral characterization under high-pressure reaction conditions and density functional theory (DFT) simulations. The research confirms that the Cu sites serve as the initial dissociation points for the hydrogen molecules. The chemically adsorbed hydrogen (H*) then spills over onto the CeO2 support and interacts with the lattice oxygen to form special hydroxyl groups, while simultaneously reducing the surrounding Ce4+ to form Ce3+. Interestingly, the temperature-programmed desorption (TPD) results found that heating the hydroxyl-containing surface mainly reverses H2 dissociation by desorbing H2 instead of forming H2O, while no significant vacancy formation was detected. The DFT calculation identified a subsurface pathway favoring hydrogen migration, which explained the dominating H2 in the TPD products. A chemical loop study after CO2/H2 cofeeding on the catalyst reveals that hydrogen spillover facilitates the highly reduced surface serving as the active centers, enabling a secondary methanol synthesis in a vacuum. This study provides a model of the formation and desorption pathways of hydrogen species on Cu/CeO2 catalysts and illustrates the key role of the hydrogen spillover mechanism in promoting the CO2 hydrogenation to methanol reaction through important experimental analysis.
研究领域:
催化化学
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材料科学
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理论计算化学
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产品关联
DOI
PubMed
高影响因子
RSC Advances
·
2021
·Vol. 11
·期 34
·21057-21065
·
IF 3.361
Dongren Cai,Bin Chen,Zhongliang Huang,Xiaoli Zeng,Jingran Xiao,Shu-Feng Zhou,Guowu Zhan
Herein, a series of metal oxide/CeO2 (M/CeO2) nanocomposites derived from Ce-benzene tricarboxylate (Ce-BTC) adsorbing with different metal acetylacetonate complexes were prepared for CO oxidation under four different CO gas atmospheres. It was demonstrated that Cu/CeO2 exhibited the highest catalytic activity and stability in CO oxidation. Remarkably, both O2 selectivity and CO selectivity to CO2 are 100% in most of the investigated conditions. Several analytical tools such as N2 adsorption–desorption and powder X-ray diffraction, were employed to characterize the prepared catalysts. In addition, the excellent catalytic performance of Cu/CeO2 in CO oxidation was revealed by H2 temperature-program reduction experiment, X-ray photoelectron spectroscopy, and in situ diffuse reflectance infrared Fourier transform spectroscopy. The result showed that high oxygen vacancy and high CO adsorption capacity (Cu+–CO) caused by the electron exchanges of Cu2+/Cu+ and Ce3+/Ce4+ pairs (Ce4+ + Cu+ ⇆ Ce3+ + Cu2+) are two key factors contributing to the high oxidation performance of Cu/CeO2 catalyst.
研究领域:
催化化学
·
材料科学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2021
·
IF 19.503
Pengchao Ren,Weifeng Tu,Chanchan Wang,Sifan Cheng,Wenqi Liu,Zhenzhou Zhang,Yun Tian,Yi-Fan Han
This study investigated the Cu-CeO 2 interactions for CO hydrogenation to methanol by applying rate measurements, chemical titration/desorption, together with in-situ/operando spectroscopy techniques under realistic reaction conditions. Ce components were enriched in the surface region of Cu/CeO 2 catalysts while Ce 3+ and Ce 4+ atoms co-existed during CO hydrogenation. The ratio of Ce 3+ to Cu 0 in the surface region of catalysts increased linearly with the Ce content. The turnover rates of CH 3 OH formation increased as a single-valued function of the ratio, irrespective to the individual contact extent between Cu and CeO 2 clusters or Ce content in the Cu/CeO 2 catalysts, indicating that the Cu 0 -Ce 3+ sites pair acts as active sites for CO hydrogenation to methanol over Ce-CeO 2 samples. This study also unraveled that formyl and formate species, as reactive surface intermediates, were co-adsorbed on the Cu 0 -Ce 3+ sites, and their hydrogenation routes occurred concurrently for CH 3 OH formation during CO-H 2 reactions.
研究领域:
催化
·
化学工程
·
表面科学
✓ 已验证
产品关联
DOI
高影响因子
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