A Pt-Sn catalyst, in which Pt clusters interact strongly with layered double oxides confined Sn sites, exhibits high dispersion of Pt (94%) with excellent stability in the regeneration treatments (oxidation-reduction cycles). Owing to the high stability, the resulting Pt clusters afford almost constant performances between the fresh catalysts and ones after 1st or 2nd oxidation-reduction cycles in both n-heptane reforming and propane dehydrogenation reactions.

Abstract

Supported Pt as catalysts have been applied for decades in industrial naphtha reforming and light alkane dehydrogenation but suffer from low stability in continuous and frequent regeneration-reaction cycles. In this work, highly stable Pt in the regeneration treatments, achieved by strong interaction with Sn sites confined in the lattice of layered double oxides (LDO), is reported. The dispersion of Pt on as-prepared clusters with lattice-confined Sn reaches 96%, and retains unchanged after the 1st and 2nd oxidation-reduction cycles (periodic calcination in air and reduction in H₂). But dramatic decrease in Pt dispersion is observed on clusters with Sn sites outside the lattice of LDO. The high stability of Pt dispersion in regeneration treatments results in almost constant performances in n-heptane reforming at 500 °C and propane dehydrogenation at 580 °C, between the fresh Pt with lattice-confined Sn catalysts and that after the 1st or 2nd oxidation-reduction cycles.