Particle size effect on catalytic activity of carbon-supported Pt nanoparticles for complete ethylene oxidation

• C2H4 oxidation reaction found to be highly size dependent over Pt/C catalyst.
• The smallest Pt nanoparticles (1.5 nm) show the highest catalytic activity.
• As Pt particle size decreases, binding energies of Pt 4f increases as shown by XPS.
• Carbon black used for the first time as a support of Pt for C2H4 complete oxidation.
• Large area carbon enhances and stabilizes the dispersion of Pt nanoparticles.

Effect of Pt particle size on the catalytic activity of complete ethylene oxidation in the temperature range of 25–220 °C in fuel-lean conditions is investigated. Carbon black is used as a support for platinum nanoparticles of well-defined average sizes between 1.5 and 6.3 nm. The results demonstrate that ethylene oxidation on Pt/C is strongly size sensitive reaction. Thus, the smallest Pt/C-4 nanoparticles (1.5 ± 0.5 nm) exhibit much higher catalytic activity toward ethylene oxidation reaching 50% conversion at 88 °C compared to 164 °C for the largest Pt/C-1 (6.3 ± 0.5 nm) nanocatalysts. XPS shows that particle size decrease results in noticeable binding energy increase and Pt4f peak broadenings. This indicates that the electronic effect induced by small Pt nanoparticles might play a role in the observed increase in their activity toward C2H4 oxidation.

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