The effects of dual promoters on the encapsulated Pt@silicalite-1 catalyst for ethane dehydrogenation

The effects of different promoters (including Sn, In, Ga, and K) on the activity, ethylene selectivity, and stability of the encapsulated Pt@silicalite-1 for ethane dehydrogenation were investigated. The dual-promoter catalysts, KPtIn@S-1 and KPtSn@S-1, exhibited high ethane initial conversions, high ethylene selectivity at 550°C, and high stability, with almost no deactivation during 30 hours on stream and the deactivation constants as low as 0.0003 and 0.0002 hour−1, respectively. Combining the characterization and performance evaluation results, it could be deduced that the introduction of Sn and In promoters plays an important role in diluting Pt, resulting in the reduced average Pt particle size. Moreover, the Sn introduced in KPtSn@S-1 led to the formation of a Si–O–Sn interaction structure between Sn and S-1 zeolite framework, resulting in the anchoring effects of Sn (II) on Pt sites. In the KPtIn@S-1 sample, the strong interaction between Pt and In also played a role in anchoring Pt species, which greatly reduced the formation of carbon deposition and inhibited the production of graphitic carbon deposits.