Abstract
Zeolites doped with metal nanoparticles have shown the outstanding activity in many processes involving heterogeneous catalysis. The size of metal nanoparticles plays a decisive role in the performance of zeolite catalysts.
However, the precise control of the size of nanoparticles is still limited. Herein, we present the synthesis of Pt-MWW zeolites with controllable nanoparticle size using a series of surfactants with different alkyl chain lengths for swelling of layered MCM-22 P.
The interlayer distances of swollen materials increases with the length of the surfactant from 1.06 nm (C12OH) to 2.89 nm (C18OH). During swelling, the Pt nanoparticles were intercalated to the interlayer space of MCM-22 P.
Further calcination resulted in Pt-MWW materials showing similar morphologies, textural properties and Pt content despite the differences in the initial interlayer distances. The factor that differentiated the synthesized materials was the average diameter of metal nanoparticles.
As a result, the average size of Pt nanoparticles increased from 0.85 nm (MCM-22-C12OH-Pt) to 2.04 nm (MCM-22-C18OH-Pt) which is related to the length of the hydrocarbon chain of the surfactant used for the swelling process.