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Gold nanoparticles supported on magnesium oxide for CO oxidation.

Carabineiro SA, Bogdanchikova N, Pestryakov A, Tavares PB, Fernandes LS, Figueiredo JL - Nanoscale Res Lett (2011)

Bottom Line: Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction.CO oxidation was used as a test reaction to compare the catalytic activity.This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratório de Catálise e Materiais, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal. scarabin@fe.up.pt.

ABSTRACT
Au was loaded (1 wt%) on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH)2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved). The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

No MeSH data available.


Size distribution histograms of Au nanoparticles on MgO, prepared by DIM (b), LPRD (c) and US (d), with respective average sizes.
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Figure 3: Size distribution histograms of Au nanoparticles on MgO, prepared by DIM (b), LPRD (c) and US (d), with respective average sizes.

Mentions: Figure 2a shows a HRTEM image of the MgO support which is quite different from what is observed in Figure 2b, c, d (MgO with Au loaded by DIM, LPRD and US, respectively), as the support changes from large crystals (Figure 2a) into a different structure (Figure 2b, c, d). Figure 3 shows the Au nanoparticle size distributions on MgO, prepared by the different methods. Gold particles are also observed with sizes ranging from 2 to 12 nm for DIM (Figures 2b, 3a). Other methods showed larger gold nanoparticle sizes between 3 and 15 nm (Figures 2c, 3b for LPRD and Figures 2d, 3c for US). The average size of gold particles is 5.4 nm for DIM and 6.6 nm for LPRD. US showed a slightly larger average gold size (6.7 nm), however the particles were closer to each other (Figure 2d).


Gold nanoparticles supported on magnesium oxide for CO oxidation.

Carabineiro SA, Bogdanchikova N, Pestryakov A, Tavares PB, Fernandes LS, Figueiredo JL - Nanoscale Res Lett (2011)

Size distribution histograms of Au nanoparticles on MgO, prepared by DIM (b), LPRD (c) and US (d), with respective average sizes.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211853&req=5

Figure 3: Size distribution histograms of Au nanoparticles on MgO, prepared by DIM (b), LPRD (c) and US (d), with respective average sizes.
Mentions: Figure 2a shows a HRTEM image of the MgO support which is quite different from what is observed in Figure 2b, c, d (MgO with Au loaded by DIM, LPRD and US, respectively), as the support changes from large crystals (Figure 2a) into a different structure (Figure 2b, c, d). Figure 3 shows the Au nanoparticle size distributions on MgO, prepared by the different methods. Gold particles are also observed with sizes ranging from 2 to 12 nm for DIM (Figures 2b, 3a). Other methods showed larger gold nanoparticle sizes between 3 and 15 nm (Figures 2c, 3b for LPRD and Figures 2d, 3c for US). The average size of gold particles is 5.4 nm for DIM and 6.6 nm for LPRD. US showed a slightly larger average gold size (6.7 nm), however the particles were closer to each other (Figure 2d).

Bottom Line: Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction.CO oxidation was used as a test reaction to compare the catalytic activity.This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

View Article: PubMed Central - HTML - PubMed

Affiliation: Laboratório de Catálise e Materiais, Departamento de Engenharia Química, Faculdade de Engenharia, Universidade do Porto, 4200-465 Porto, Portugal. scarabin@fe.up.pt.

ABSTRACT
Au was loaded (1 wt%) on a commercial MgO support by three different methods: double impregnation, liquid-phase reductive deposition and ultrasonication. Samples were characterised by adsorption of N2 at -96°C, temperature-programmed reduction, high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction. Upon loading with Au, MgO changed into Mg(OH)2 (the hydroxide was most likely formed by reaction with water, in which the gold precursor was dissolved). The size range for gold nanoparticles was 2-12 nm for the DIM method and 3-15 nm for LPRD and US. The average size of gold particles was 5.4 nm for DIM and larger than 6.5 for the other methods. CO oxidation was used as a test reaction to compare the catalytic activity. The best results were obtained with the DIM method, followed by LPRD and US. This can be explained in terms of the nanoparticle size, well known to determine the catalytic activity of gold catalysts.

No MeSH data available.