Structure dependence and reaction mechanism of CO oxidation: A model study on macroporous CeO2 and CeO2-ZrO2 catalysts

Zheng, Yane; Li, Kongzhai; Wang, Hua; Wang, Yuhao; Tian, Dong; Wei, Yonggang; Zhu, Xing; Zeng, Chunhua; Luo, Yongming

doi:10.1016/j.jcat.2016.10.008

Cited by 166 publications

(71 citation statements)

References 65 publications

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“…Lee et al [20] conducted a kinetics study and reported a detailed reaction pathway of the L-H mechanism, where CO absorbs onto the surface of CuO and reacts at Cu-Ce-O interfaces with neighboring surface-bound oxygen adsorbed onto CeO 2 . Recently, Zheng et al [21] confirmed by in situ diffusereflectance Fourier transform (DRIFT) analysis that the CO oxidation follows both the M-K and L-H mechanisms. On the one hand, the CeO 2 provides active sites for CO and O 2 chemisorption to form bicarbonate, unidentate carbonate and bidentate carbonate species for interactions; on the other hand, the lattice oxygen of the Ce-Zr solid solution reacts with the chemisorbed CO to form bridging carbonates.…”

Section: Introductionmentioning

confidence: 99%

Reaction mechanism and kinetics of CO oxidation over a CuO/Ce0.75Zr0.25O2-δ catalyst

Kang

Wei

Bin

et al. 2018

Applied Catalysis A: General

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A B S T R A C T The CuO/Ce 0.75 Zr 0.25 O 2δ and Ce 0.75 Zr 0.25 O δ catalysts were prepared by the sol-gel method, and Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ was obtained by treating CuO/Ce 0.75 Zr 0.25 O 2δ with nitric acid to remove the well-dispersed CuO on the surface. Various characterizations were used to reveal the different active sites, such as surface-dispersed CuO and Cu-Ce-Zr-O δ solid solutions in CuO/Ce 0.75 Zr 0.25 O 2δ , Cu-Ce-Zr-O δ solid solutions in Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ and Ce-Zr-O δ solid solutions in Ce 0.75 Zr 0.25 O δ . The Raman and O 2 -TPD results showed that the concentration of oxygen vacancies in Cu-Ce-Zr-O δ solid solutions was higher than that in Ce-Zr-O δ solid solutions. CO oxidation testing suggested that the catalytic activity decreases in the order of CuO/ Ce 0.75 Zr 0.25 O 2δ > Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ > Ce 0.75 Zr 0.25 O δ .Combined with the in situ diffuse-reflectance Fourier transform (in situ DRIFT) results, the reaction sensitivity followed the order of CO linear chemisorption onto dispersed CuO x species (Mars-van Krevelen mechanism) > carbonate species onto a Cu-Ce-Zr-O δ solid solution (Langmuir-Hinshelwood mechanism) > carbonate species onto a Ce-Zr-O δ solid solution (Langmuir-Hinshelwood mechanism). Kinetic studies suggested that the power-law rate expressions and apparent activation energies were r = 6.02 × 10 −7 ×P CO 0.68 P O2 0.03 (53 ± 3 kJ/mol) for CuO/Ce 0.75 Zr 0.25 O 2δ , r = 5.86 × 10 −7 ×P CO 0.8 P O2 0.07 (105 ± 5 kJ/mol) for Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ and r = 5.7 × 10 −7 ×P CO 0.75 P O2 0.12 (115 ± 6 kJ/mol) for Ce 0.75 Zr 0.25 O δ . The Mars-van Krevelen mechanism should be the crucial reaction pathway over CuO/Ce 0.75 Zr 0.25 O 2δ in CO interfacial reactions, although the Langmuir-Hinshelwood mechanism cannot be ignored, and the Langmuir-Hinshelwood mechanism mainly occurred over the Cu 0.07 Ce 0.75 Zr 0.25 O 2-δ and Ce 0.75 Zr 0.25 O δ catalysts, where the contribution from the Mars-van Krevelen mechanism was negligible due to the absence of surface CuO x species.

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Section: Introductionmentioning

confidence: 99%

Reaction mechanism and kinetics of CO oxidation over a CuO/Ce0.75Zr0.25O2-δ catalyst

Kang

Wei

Bin

et al. 2018

Applied Catalysis A: General

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“…These materials have a structure with regular large pore size and coadjacent macroporous channels with high approachable surface area, which ensure abundant exposure to the reactants. On the other hand, the three-dimensional transfixion pore structure is also beneficial to mass diffusion and improves the catalytic activity [18][19][20][21][22][23]. For example, Au embedded onto 3DOM CeO 2 exhibited excellent catalytic activity/selectivity in formaldehyde oxidation [24,25].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Three-Dimensionally Ordered Macroporous NiCe Catalysts for Oxidative Dehydrogenation of Propane to Propene

et al. 2018

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Three-dimensionally ordered macroporous (3DOM) NiCe catalysts with different Ni/Ce molar ratio were fabricated using the colloidal crystal templating method. The physic-chemical properties of the samples were characterized by various techniques, including N 2 adsorption-desorption, X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, and H 2 -temperature-programmed reduction (TPR) characterizations. The results revealed that the 3DOM NiCe samples preserved the three-dimensionally ordered macroporous channels with interlinked micro-or mesoporous structure and highly dispersed nickel oxide species in the framework upon different amount of nickel incorporation. In the evaluation of the oxidative dehydrogenation (ODH) of propane, the 3DOM NiCe catalysts exhibited higher selectivity and yield to propene than the amorphous NiCe catalyst. An optimum yield of propene of 11.9% with the 30.3% propane conversion at 375 • C was obtained over the 3DOM 2NiCe catalyst. Combining XRD, TPR, and Raman analysis, it could be found that the nickel incorporation in CeO 2 lattice produced a high concentration of oxygen vacancies that were the active sites for the oxidative dehydrogenation of propane. Besides this, the 3DOM structure promoted the rapid diffusion of the reactants and products-favorable for the generation of propene in the ODH of propane.

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“…Combined with H 2 -TPR and XPS experiments, it suggested that CO oxidation over LaO x -doped CeO 2 -supported Au catalysts might follow the Langmuir–Hinshelwood + Redox mechanism [1, 20, 26, 30, 32]. The XPS results suggest that there are Ce 3+ and Ce 4+ on the surface of the catalyst.…”

Section: Resultsmentioning

confidence: 91%

“…For pure CeO 2 nanorods, the reduction peak centered at about low temperature (410 °C) and high temperature (620 °C) could be attributed to the reduction of surface and bulk oxygen species of CeO 2 , respectively [1, 32]. For pure La nanorods, obvious reduction peaks could be detected at ~ 700 °C assigned to the reduction of bulk La 2 O 3 .…”

Section: Resultsmentioning

confidence: 99%

“…It has become an increasingly severe problem on air pollution. Catalytic CO oxidation has been one of the most effective solutions for CO removal to solve such serious environmental problem [1–8]. It has also received a great deal attention recently by the scientific community in the fields of the pollution control devices for vehicle exhaust purification, indoor air cleaning, and low-temperature CO sensors [6–10].…”

Section: Introductionmentioning

confidence: 99%

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Synthesis and CO Oxidation Activity of 1D Mixed Binary Oxide CeO2-LaO x Supported Gold Catalysts

Zhong

Zhu

et al. 2017

Nanoscale Res Lett

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One-dimensional (1D) Ce-La nanorods with different La contents (Ce and La in the molar ratio of 1:0, 3:1, 1:1, 1:3, and 0:1) were synthesized by hydrothermal process. Au/Ce-La nanorod catalysts were obtained by a modified deposition-precipitation method. The samples were characterized by N2 adsorption-desorption (BET), ICP, X-ray diffraction (XRD), SEM, TEM, EDX, X-ray photoelectron spectroscopy (XPS), UV-vis diffuse reflectance spectroscopy (UV-vis DRS), and temperature-programmed reduction (H2-TPR). It revealed that La existed as LaOx in the 1D nanorods. The catalysis results demonstrated that the mixed binary Ce-La nanorod oxides could be a good support for gold catalysts. The contents of La had an important influence on the catalytic performance of Au/Ce-La nanorod catalysts. Among the catalysts, when the Ce/La molar ratio was 3:1, the 1.0%Au/Ce0.75-La0.25 nanorods pretreated at 300 °C showed the best activity among the catalysts for CO oxidation, which could convert CO completely at 30 °C. The catalysts also performed high temperature resistance and good stability for CO oxidation at the reaction temperatures of 40, 70, and 200 °C.

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Structure dependence and reaction mechanism of CO oxidation: A model study on macroporous CeO2 and CeO2-ZrO2 catalysts

Cited by 166 publications

References 65 publications

Reaction mechanism and kinetics of CO oxidation over a CuO/Ce0.75Zr0.25O2-δ catalyst

Reaction mechanism and kinetics of CO oxidation over a CuO/Ce0.75Zr0.25O2-δ catalyst

Synthesis of Three-Dimensionally Ordered Macroporous NiCe Catalysts for Oxidative Dehydrogenation of Propane to Propene

Synthesis and CO Oxidation Activity of 1D Mixed Binary Oxide CeO2-LaO x Supported Gold Catalysts

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