Pt–CeO2 nanoporous spheres – an excellent catalyst for partial oxidation of methane: effect of the bimodal pore structure†
Pt–CeO2 nanoporous spheres were prepared by a two-step synthesis procedure. First, CeO2 nanoporous spheres were prepared by a solvo-thermal method followed by Pt-loading by controlled deposition. The synthesized catalysts were characterized by BET-surface area, H2-chemisorption, XRD, H2-TPR, SEM, TEM, XPS, Raman analysis and EXAFS techniques. The prepared Pt–CeO2NP catalyst showed a bimodal pore structure, which highly influenced its catalytic activity. The catalyst activates methane at 350 °C and was found to be highly active and selective for synthesis gas production via partial oxidation of methane. Pt-nanoparticles of 1.27 nm on average supported on about 150 nm nanoporous spheres comprised of 5–15 nm CeO2 particles were stable for more than 60 h of time-on-stream (TOS) without any significant activity loss, producing synthesis gas with an H2/CO ratio ∼1.95. The high surface area and bimodal pore size distribution played the most important role for the catalyst's superior activity.