The selective oxidation of CO over C 3 H 6 is achieved in yolk-shell Pt@Silicalite-1 catalysts in which Pt nanoparticles are encapsulated in hollow silicalite-1 single crystals. The thin shell operates as a permselective membrane which limits Pt surface poisoning by C 3 H 6 . From adsorption measurements, we conclude that the catalytic selectivity arises from the fastest diffusion of CO over C 3 H 6 through the silicalite-1 membrane.

Rouquerol criterion and the BET equation is in accord with the geometrical surface determined by the chord length distribution method. Therefore BET surface area (S BET) is well representative of micropore surface areas of microporous materials and of total surface area of microporous/mesoporous materials. Mechanical mixtures of mesoporous MCM-41 and microporous FAU-Y powders of known surface areas were used to calculate the respective surface areas by weighted linear combination and the results were compared to the values obtained by the t-plot method. The first slope of the t-plot determined the mesopore + external surface areas (S mes+ext). The linear fit of the first slope is in general in the range 0.01 < p/p 0 < 0.17 and contains the volumes and relative pressures at which all micropores are filled (p/p 0 > 0.10). Overestimation of S mes+ext values was evident and appropriate corrections were provided. External surface areas (S ext) were obtained from the second slope of the t-plot, without noting an overestimation of S ext , thus allowing the determination of mesopore surface areas (S mes) by difference. Micropore surface areas were calculated by subtracting S mes+ext from the total surface area, S BET. As an example, this methodology was applied to the characterization a family of hierarchical microporous/mesoporous FAU-Y (FAUmes) synthesized from H-FAU-Y (H-Y, Si/Al = 15) using C18TAB as surfactant and different NaOH/Si ratio (0.05 < NaOH/Si < 0.25). By increasing the NaOH/Si ratio in synthesis of FAUmes, it was shown that as the micropore surface area decreases, the mesopore surface area increases, while the micropore + mesopore surface area remains constant. This methodology allows accurate characterization of the surface areas of microporous/mesoporous materials.

We report an original and scalable synthesis pathway to produce encapsulated gold nanoparticles. Precise control of the gold particles is achieved in the range of 1-10 nm through the impregnation of silicalite-1 with a controlled concentration of gold solution, followed by dissolution-recrystallization of the zeolite.