2018 **Abstract:** The use of surface organometallic chemistry on metal (SOMC/M) allows the controlled and stepwise variation of the platinum particle size in Pt/SiO 2 catalysts. This SOMC/M method is possible thanks to the better affinity of most organometallic compounds with the surface of zerovalent metal particles covered with hydrogen than their support. In this paper, Pt(acac) 2 was used as the organometallic precursor, silica as a support, and then hydrogen to reduce the adsorbed organometallic layer on top of the startin…

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“…The surface area and pore volume increased slightly upon the addition of the Pd clusters. At 50 °C, a Pd dispersion of 19% was measured corresponding to an average (spherical) Pd size of 5.8 nm using where D is the dispersion (%), M is the atomic weight, ρ is the density of the metal, N a is Avogadro’s number, S a is the area of each surface atom, and d is the diameter (nm). − The surface area and pore volume of the Pt catalyst both decreased as expected for incipient wetness impregnation. No measurable CO or H 2 uptake was found on the Pt catalyst at 23, 50, or 100 °C; therefore, dispersion was calculated approximately from the XPS measurement by quantifying the Fe 2p and Pt 4f peaks, relating the peak areas to moles of each element, and dividing the calculated exposed Pt from XPS by the total number of Pt.…”

confidence: 97%

“…The surface area and pore volume increased slightly upon the addition of the Pd clusters. At 50 °C, a Pd dispersion of 19% was measured corresponding to an average (spherical) Pd size of 5.8 nm using where D is the dispersion (%), M is the atomic weight, ρ is the density of the metal, N a is Avogadro’s number, S a is the area of each surface atom, and d is the diameter (nm). − The surface area and pore volume of the Pt catalyst both decreased as expected for incipient wetness impregnation. No measurable CO or H 2 uptake was found on the Pt catalyst at 23, 50, or 100 °C; therefore, dispersion was calculated approximately from the XPS measurement by quantifying the Fe 2p and Pt 4f peaks, relating the peak areas to moles of each element, and dividing the calculated exposed Pt from XPS by the total number of Pt.…”

confidence: 97%

“…The platinum particle size was determined from TEM micrographs through Equation (): $${\mathrm{normald}}_{\mathrm{Pt}}=\frac{{\sum}_{\mathrm{normali}}\left({n}_{\mathrm{normali}}{d}_{\mathrm{normali}}^{3}\right)}{{\sum}_{\mathrm{normali}}\left({n}_{\mathrm{normali}}{d}_{\mathrm{normali}}^{2}\right)}$$ where n i is the number of metal particles with size d i . The platinum particle diameter was also calculated from H 2 uptake of chemisorption experiments assuming a spherical geometry (Al‐Shareef et al, 2018): $${d}_{\mathrm{Pt}}=\frac{6\phantom{\rule{0.25em}{0ex}}\mathrm{M}}{{\rho}_{\mathrm{normalM}}\phantom{\rule{0.25em}{0ex}}\mathrm{\varphi}\phantom{\rule{0.25em}{0ex}}{\mathrm{normalN}}_{\mathrm{AV}}{\mathrm{normalS}}_{\mathrm{normala}}}$$ where $\mathrm{\varphi}$ is the metal dispersion, ${d}_{\mathrm{Pt}}$ is the diameter of the platinum particles (m), M is the atomic weight, ρ M is the density of the metal (21,450 kg/m 3 ), N AV is the Avogadro number, and S a is the surface area of the Pt atom. Figure 2 shows the particle size distribution of the Pt based synthesized catalysts determined from TEM micrographs according to Equation () for 500 platinum particles.…”

confidence: 99%

“…The platinum particle diameter was also calculated from H 2 uptake of chemisorption experiments assuming a spherical geometry (Al-Shareef et al, 2018):…”

confidence: 99%

“…Interestingly, the energy of this vibration appeared to increase as the calcination temperature of the support was increased. Increases in vibration bond energies in such catalysts have previously been attributed to decreases in bond length, which, in turn, can be indicative of increased electron density in the particle. If this is indeed the case here, then it could suggest that substrate binding energy might influence the reaction selectivity.…”

confidence: 99%

“…Given that metal particle size can influence electronic properties, 48 it seemed logical to assess whether the Pt particle size, in the Pt/TiO 2 catalysts, could also influence selectivity. As we have already demonstrated that the phase of the support can influence reactivity, it was important to develop a method to probe this without changing the composition of the support.…”

confidence: 99%