“…The presence of Au δ+ is responsible for the partial reduction of the support surface. Accordingly, Au δ+ is considered to be more active than Au 0 for CO oxidation [11, 21]. In our case, the catalysts calcined at 300 °C had more Au δ+ than that calcined at 400 °C, so it is not difficult to deduce the catalysts calcined at 300 °C were more active than the catalysts calcined at 400 °C, which was consistent with the activity results.Fig.…”
Section: Resultssupporting
confidence: 89%
“…7. As seen in this figure, compared with the spectra of the support, the spectra of the catalysts calcined at different temperatures exhibited weak and broad absorption band between 500 and 600 nm which was characterize for the surface plasmon resonance (SPR) of metallic gold nanoparticles [21, 24, 49]. The SPR could be ascribed to the collective oscillations of electrons in response to optical excitation, which would result in the absorption of light in the Uv-vis region.…”
Section: Resultsmentioning
confidence: 99%
“…8b, after the deposition of gold, a new reduction peak at very low temperature (100–200 °C) appears for Au/CeO 2 and Au/La-Ce nanorods. Here, due to XPS results, after the catalysts were calcined at 300 °C, Au was mainly Au δ+ , so the reduction peaks at ~ 200 °C is attributed to the reduction of Au species in high valence [21]. The small peak centered at ~ 350 °C can be associated with the reduction of Ce-La nanorods.…”
Section: Resultsmentioning
confidence: 99%
“…Consequently, the gold particles of Au/Ce 0.75 -La 0.25 nanorods were detected as sub-nanometer. Taking into account the particle size, mass content, and chemical states of the gold nanoparticles, gold particles with small diameter highly dispersed on the surface of Ce 0.75 -La 0.25 nanorods and interacted strongly with the support [17, 21, 23]. The strong interaction between gold particles and the support would help improve CO adsorption and accelerate active oxygen spillover to gold particles from the support, so 0.5% Au/Ce 0.75 -La 0.25 nanorods which had relatively high content of gold should exhibit the best CO oxidation activity.…”
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.
“…The presence of Au δ+ is responsible for the partial reduction of the support surface. Accordingly, Au δ+ is considered to be more active than Au 0 for CO oxidation [11, 21]. In our case, the catalysts calcined at 300 °C had more Au δ+ than that calcined at 400 °C, so it is not difficult to deduce the catalysts calcined at 300 °C were more active than the catalysts calcined at 400 °C, which was consistent with the activity results.Fig.…”
Section: Resultssupporting
confidence: 89%
“…7. As seen in this figure, compared with the spectra of the support, the spectra of the catalysts calcined at different temperatures exhibited weak and broad absorption band between 500 and 600 nm which was characterize for the surface plasmon resonance (SPR) of metallic gold nanoparticles [21, 24, 49]. The SPR could be ascribed to the collective oscillations of electrons in response to optical excitation, which would result in the absorption of light in the Uv-vis region.…”
Section: Resultsmentioning
confidence: 99%
“…8b, after the deposition of gold, a new reduction peak at very low temperature (100–200 °C) appears for Au/CeO 2 and Au/La-Ce nanorods. Here, due to XPS results, after the catalysts were calcined at 300 °C, Au was mainly Au δ+ , so the reduction peaks at ~ 200 °C is attributed to the reduction of Au species in high valence [21]. The small peak centered at ~ 350 °C can be associated with the reduction of Ce-La nanorods.…”
Section: Resultsmentioning
confidence: 99%
“…Consequently, the gold particles of Au/Ce 0.75 -La 0.25 nanorods were detected as sub-nanometer. Taking into account the particle size, mass content, and chemical states of the gold nanoparticles, gold particles with small diameter highly dispersed on the surface of Ce 0.75 -La 0.25 nanorods and interacted strongly with the support [17, 21, 23]. The strong interaction between gold particles and the support would help improve CO adsorption and accelerate active oxygen spillover to gold particles from the support, so 0.5% Au/Ce 0.75 -La 0.25 nanorods which had relatively high content of gold should exhibit the best CO oxidation activity.…”
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.
“…Mono-and bi-metallic Au and Cu have been reported as promising active metals in WGSR [14,18,19] and CO-PROX [20]. The support also plays an important role in catalyst performance for CO removal.…”
The integration of H2 production and purification is an essential step in the development of sustainable power generation in proton exchange membrane fuel cells. Thence, coupling of steam reforming of ethanol (SRE) and carbon monoxide removal was evaluated for further hydrogen production in fuel cells. Firstly, SRE on RhPt/CeO2-SiO2 catalyst was carried out at 700 °C, displaying a stable product distribution for 120 h. Then, CO removal from the actual post-reforming stream was evaluated over several AuCu/CeO2 catalysts with different Au:Cu weight ratios (1:0, 3:1, 1:1, 1:3, and 0:1). The role of each active metal was identified: Au favors CO conversion by the formation of carbon intermediates, and Cu improves CO2 selectivity due to its redox properties. A 1:1 Au:Cu weight ratio on the AuCu/CeO2 catalyst at 210 °C favors complete CO removal from the post-reforming stream, achieving fuel-cell grade hydrogen production. However, 25% of H2 was loss during the CO removal step, which is very high compared to studies with synthetic feeds. These high H2 loss would be the result of a complex network of reactions occurring during the real post-reforming cleaning. Characterization tests allowed us to identify that CeO2, combined with the Cu redox properties, favors water decomposition and CO conversion. Likewise, catalyst reduction might favor Au-Cu alloy formation due to the similar crystal lattice. Finally, stability tests showed that Au1.0Cu1.0/CeO2 catalyst is susceptible to rearrangement due to the cumulative oxidation of its surface during operation. Nonetheless, periodic insitu reduction treatment contributes to the Au-Cu alloy formation and stabilization, maintaining high activity and mitigating H2 loss. Indeed, Au1.0Cu1.0/CeO2 catalyst was active for 95 h when reduced every 24 h, achieving fuel-cell grade hydrogen with a minimum of 14% H2 loss.
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