Determination of metal particle size of highly dispersed Rh, Ir, and Pt catalysts by hydrogen chemisorption and EXAFS

Kip, BJ; Duivenvoorden, F.B.M.; Koningsberger, D.C.; Prins, R.

doi:10.1016/0021-9517(87)90005-4

Cited by 303 publications

(115 citation statements)

References 55 publications

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“…Similar effect has been reported for the supported metallic catalyst, e.g. Pt/Al 2 O 3 or Pt/Al 2 O 3 /SnO 2 [22]. Effectiveness of dispersion of the oxide component is confirmed by the XRD studies whose results point to the greatest contribution of the amorphous gel structure in the samples synthesised by the non-aqueous methods.…”

Section: Resultssupporting

confidence: 78%

Influence of the method of synthesis on hydrogen adsorption properties of mesoporous binary B2O3/Al2O3 gel systems

Martyła¹,

Olejnik²,

Kirszensztejn³

et al. 2011

International Journal of Hydrogen Energy

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Section: Resultssupporting

confidence: 78%

Influence of the method of synthesis on hydrogen adsorption properties of mesoporous binary B2O3/Al2O3 gel systems

Martyła¹,

Olejnik²,

Kirszensztejn³

et al. 2011

International Journal of Hydrogen Energy

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“…It should be mentioned that for the determination of the particle size with H 2 -chemisorption several assumptions were made, including that Pt formed (hemi)spherical particles and that the H:Pt s stoichiometry was 1. The H:Pt s stoichiometry can, however, be larger than 1, [33] and thus lead to underestimation of Pt particle sizes. Even with this taken into account, the values obtained by H 2 -chemisorption were in a size range of those obtained by TEM, confirming that the large particles did not greatly contribute to the average particle size and that the majority of Pt particles are 1-2 nm in diameter in all catalysts.…”

Section: Samplementioning

confidence: 99%

The Origin of Metal Loading Heterogeneities in Pt/Zeolite Y Bifunctional Catalysts

2019

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Preparing catalysts with highly dispersed metal nanoparticles and narrow particle size distribution has been in the focus of numerous studies. Besides size and size distribution, the location of metal nanoparticles within and local metal loading of the support can have significant impact on catalytic performance. This study revealed that great variations in Pt loading between individual Pt/zeolite Y crystals occurred irrespective of the metal deposition method, namely ion‐exchange (IE) or incipient wetness impregnation (IWI). The variation in Pt loading was found to be directly related to different Si/Al ratios of individual zeolite crystals. Results indicate that this Si/Al variation was likely induced by post‐synthesis treatments, commonly performed to introduce mesoporosity. In view of the great importance of zeolite‐based catalysts for oil refining, understanding the origin of such metal loading heterogeneities may lead to further improvement of zeolite‐based catalytic performance.

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“…After in situ H 2 reduction at 300 8C, all of the Pt species were reduced to the metallic phase, yet the Pt-Pt coordination number was monotonically lowered with an increase in the amount of Na. The relationship between Pt particle size and Pt-Pt coordination number determined by EXAFS is well-established, [27] whereby the metal-metal coordination number is a function of the total number of metal atoms in one particle and a smaller coordination number corresponds to a smaller particle size. [28] Thus, the EXAFS findings show that Na addition effectively reduces the particle size of Pt from 10 (Na-free), to 6.8 (1 % Na), to 4.8 nm (2 % Na).…”

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Alkali‐Metal‐Promoted Pt/TiO₂ Opens a More Efficient Pathway to Formaldehyde Oxidation at Ambient Temperatures

et al. 2012

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Formaldehyde is emitted from building and furnishing materials and consumer products, [1] and is known to cause irritation of eyes and respiratory tract, headache, pneumonia, and even cancer. [2,3] It is a dominant indoor air pollutant, especially in developing countries, and significant efforts have gone into indoor HCHO purification to meet environmental regulations and human health needs.Removal of HCHO by adsorbents has been investigated extensively using potassium permanganate, activated carbon, aluminum oxide, and some ceramic materials. [4][5][6] Sorbent effectiveness is typically limited by low adsorption capacities. Catalytic oxidation is the most effective technology for volatile organic compound (VOC) abatement because VOCs can be oxidized to CO 2 over certain catalysts at much lower temperatures than in thermal oxidation. [7][8][9] Supported noble metal catalysts (Pt, Pd, Rh, Au, Ag) or metal oxide catalysts (Ni, Cu, Cr, Mn) have been used for the catalytic oxidation of VOCs. [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22] Complete oxidation of HCHO over catalysts occurs above 150 8C on clean and oxidized films of Ni, Pd, and Al [15] and over silver-cerium composite oxide, [16] above 100 8C over Ag/MnOx-CeO 2 [18] and Au/CeO 2 , [19] and above 85 8C over Pd-Mn/Al 2 O 3[17] and Au/FeOx. [20] As catalytic oxidation at even lower temperatures is desirable for indoor air purification, the development of a catalyst for total HCHO oxidation at room temperature is of great interest. In our recent study, [21,22] 1 % Pt/TiO 2 catalyst was shown to be effective for HCHO oxidation at room temperature, achieving 100 % conversion of d = 100 ppm HCHO to CO 2 and H 2 O at a gas hourly space velocity (GHSV) of 50 000 h À1 . However, we also observed that this type catalyst is not as active as needed for practical applications, and deactivates with time-on-stream.Herein, we report a novel alkali-metal-promoted Pt/TiO 2 catalyst for the ambient destruction of HCHO. We show that the addition of alkali-metal ions (such as Li + , Na + , and K + ) to Pt/TiO 2 catalyst stabilized an atomically dispersed Pt-O(OH)x-alkali-metal species on the catalyst surface and also opened a new low-temperature reaction pathway, significantly promoting the activity for the HCHO oxidation by activating H 2 O and catalyzing the facile reaction between surface OH and formate species to total oxidation products.Figure 1 a shows the HCHO conversion to CO 2 as a function of temperature over the x % Na-1 % Pt/TiO 2 (x = 0, 1, and 2) samples at a GHSV of 120 000 h À1 and HCHO inlet of d = 600 ppm. All gas streams were humidified to a RH of around 50 %. Before each activity test, the samples were reduced in H 2 at 300 8C for 30 min. The sodium-free catalyst had low activity for the HCHO oxidation reaction, with HCHO conversion being only about 19 % at 15 8C. With 1 % Na addition, the HCHO conversion reached 96 % at 15 8C and 100 % at 40 8C. With 2 % Na addition, 100 % HCHO conversion to CO 2 and H 2 O was measured at 15 8C. The effect of ...

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Determination of metal particle size of highly dispersed Rh, Ir, and Pt catalysts by hydrogen chemisorption and EXAFS

Abstract: Prins, R. (1986). Determination of metal particle size of highly dispersed Rh, Ir, and Pt catalysts by hydrogen chemisorption and EXAFS.

Cited by 303 publications

References 55 publications

Influence of the method of synthesis on hydrogen adsorption properties of mesoporous binary B2O3/Al2O3 gel systems

Influence of the method of synthesis on hydrogen adsorption properties of mesoporous binary B2O3/Al2O3 gel systems

The Origin of Metal Loading Heterogeneities in Pt/Zeolite Y Bifunctional Catalysts

Alkali‐Metal‐Promoted Pt/TiO₂ Opens a More Efficient Pathway to Formaldehyde Oxidation at Ambient Temperatures

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Determination of metal particle size of highly dispersed Rh, Ir, and Pt catalysts by hydrogen chemisorption and EXAFS

Abstract: Prins, R. (1986). Determination of metal particle size of highly dispersed Rh, Ir, and Pt catalysts by hydrogen chemisorption and EXAFS.

Cited by 303 publications

References 55 publications

Influence of the method of synthesis on hydrogen adsorption properties of mesoporous binary B2O3/Al2O3 gel systems

Influence of the method of synthesis on hydrogen adsorption properties of mesoporous binary B2O3/Al2O3 gel systems

The Origin of Metal Loading Heterogeneities in Pt/Zeolite Y Bifunctional Catalysts

Alkali‐Metal‐Promoted Pt/TiO2 Opens a More Efficient Pathway to Formaldehyde Oxidation at Ambient Temperatures

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Alkali‐Metal‐Promoted Pt/TiO₂ Opens a More Efficient Pathway to Formaldehyde Oxidation at Ambient Temperatures