Support Screening\nto Shape Propane Dehydrogenation\nSnPt-Based Catalysts

Propane dehydrogenation\nreaction (PDH) is an extremely attractive\nway to produce propylene; however, the catalysts often lead to byproduct\nformation and suffer from deactivation. This research focuses on the\ndevelopment of efficient Pt/Sn-based shaped catalysts by utilizing\nMg-modified mesoporous silica, sepiolite (natural SiMgO<sub><i>x</i></sub> mesoporous clay), and sepiolite/bentonite/alumina\nas supports with the aim of achieving superior stability and selectivity\nfor industrial propylene production by PDH. The catalysts were prepared\nby sequential impregnation of the supports with the corresponding\nsolutions of tin chloride and platinum chloride, by obtaining a nominal\nloading of 0.7 wt % of Sn and 0.5 wt % of Pt. A range of analytical\ntechniques were used to characterize the catalysts, including X-ray\ndiffraction, nitrogen physisorption isotherms, Hg intrusion porosimetry,\nthermogravimetric analyses, transmission electron microscopy, Raman\nspectroscopy, and X-ray photoelectron spectroscopy. The basicity of\nthe catalysts was assessed using carbon dioxide temperature-programmed\ndesorption (CO<sub>2</sub>-TPD). The results confirm that the support\nmaterial plays a critical role in catalyst performance; in particular,\nthe presence of weak basic sites, due to magnesium addition, improved\nselectivity to propylene and reduced coke formation. Catalytic pellets\nof Sn–Pt supported on macroporous sepiolite or sepiolite and\nbentonite-modified mesoporous alumina performed comparably with propane\nconversion very close to thermodynamic equilibrium and selectivity\nto propylene above 95%. The latter support led to improved stability\nand was regenerated at milder temperatures, making it suitable for\nindustrial applications.