Resolving Complex K-Pt-Sn Interactions in PtSn@K-MFI Catalysts for Alkane Dehydrogenation.

Area of Science:

• Materials Science
• Catalysis Science

Background:

• Developing efficient catalysts for propane dehydration (PDH) is crucial for industrial applications.
• Optimizing metal dispersion and stability in zeolite-based catalysts remains a challenge.

Purpose of the Study:

• To rationalize potassium (K) and tin (Sn) content during the synthesis of PtSn@K-MFI catalysts.
• To investigate the impact of K and Sn stoichiometry on metal dispersion, stability, and catalytic performance in PDH reactions.

Main Methods:

• Synthesis of PtSn@K-MFI catalysts with varying K and Sn loadings.
• Experimental characterization and theoretical calculations to determine K incorporation limits and metal interactions.
• Evaluation of catalytic performance and deactivation/regeneration profiles in the propane dehydration reaction.

Main Results:

• A K stoichiometry of ~1 K per MFI unit cell limits K incorporation to ~0.7 wt% without Sn.
• Excess K leads to tin-silicate precipitates unless significant Sn is present.
• Optimized PtSn@K-MFI catalysts outperform PtSn/SiO2 in PDH.
• Low Sn (<0.5 wt%) offers better regenerability but faster deactivation; high Sn (~1 wt%) minimizes deactivation but causes sintering upon regeneration.

Conclusions:

• Fine-tuning the one-pot synthesis of PtSn@K-MFI catalysts is key to controlling metal interactions and catalytic properties.
• Catalyst performance and stability are highly dependent on the precise K and Sn content and their interplay.
• Understanding nucleation and crystallization is vital for designing robust catalysts for demanding industrial conditions.