VOCs abatement using thick eggshell Pt/SBA-15 pellets with hierarchical porosity

• Mechanically stable 3-D pellets with hierarchical porosity made of SBA-15 silica fibers.
• Thick egg-shell distribution of in situ assembled small Pt nanoparticles.
• No deactivation observed in the total oxidation of n-hexane after 70 h on stream.

Mechanically stable 3-D pellets made of mesoporous SBA-15 silica fibers containing highly dispersed platinum nanoparticles have been successfully synthesized with the aid of a sacrificial polyacrylamide network using a gel-casting deposition technique. The pellets exhibit a hierarchical porosity, with spaces of 3 microns among the silica fibers, and a core–shell distribution of Pt, with an outer Pt-rich layer of 450 microns accounting for over 73% of the Pt. Both factors (hierarchical structure and concentration of the catalyst on the outer pellet surface) facilitated reactant access to the catalyst centers, and as a consequence an excellent catalytic activity toward the total oxidation of n-hexane, used as a VOC model. There was no measurable loss of activity after 70 h on stream and the subsequent examination of the catalyst revealed that interparticle coalescence of Pt nanoparticles was largely prevented due to the encapsulation of the noble-metal particles within the silica mesochannels.

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