Fe-Substituted Pt/HZSM-48 for Superior Selectivity of i-C₁₂ in n-Dodecane Hydroisomerization

A series of Fe-substituted ZSM-48 catalysts including Fe-free HZ48 and partially and fully Fe-substituted HZ48-x (x = Al/Fe = 9, 5, 1, and 0) is synthesized via an in situ seed-induced hydrothermal process with the aim to improve the iso-selectivity of long-chain n-alkane hydroisomerization. X-ray powder diffraction, UV-vis, UV-Raman, and X-ray photoelectron spectroscopy analyses confirm that Fe3+ species are effectively incorporated into the *MRE framework. NH3-TPD and Py-IR show that not only the strength of strong acid reduces with the increased Fe-substitution, the total Bronsted acidity also decreases. To support hydroisomerization of n-C-12, Pt is loaded to the HZ48 and HZ48-x supports. The reaction testing shows that the Fe-substitution consistently increases the isomer yield than the Fe-free Pt/HZ48. The partially Fe-substituted Pt/HZ48-5 delivers the highest isomer yield of 78.9% i-C-12, a 15.7% increase compared to the Fe-free Pt/HZ48 catalyst. The iso-selectivity achieved also shows a strong positive correlation with the BW+M% of the catalysts.