Effect of iron oxide on isobutane dehydrogenation over Pt/Fe2O3-Al2O3 catalyst

The effect of adding Fe2O3 to an Al2O3-supported Pt catalyst on isobutane dehydrogenation was studied. Catalytic activity, catalyst stability, and selectivity to isobutene were improved significantly by adding a small amount of Fe2O3 to Pt/Al2O3. The catalysts were characterized by CO and NH3 chemisorption measurements, Fourier transformed-infrared (FT-IR) analysis of adsorbed CO, and thermogravimatric-differential thermal analysis (TG-DTA) of the used catalyst. FT-IR analysis of the adsorbed CO showed that the electron density of Pt was increased by the formation of bimetallic particles. CO chemisorption suggested the formation of Pt-Fe bimetallic particles partially covered with Fe species. Furthermore, the number of strong acid sites on the Al2O3 surface was decreased by adding Fe2O3. Analysis of the used catalysts suggested that the addition of Fe2O3 inhibited sintering of supported Pt particles. The addition of Sn to Pt/Fe2O3-Al2O3 further improved the dehydrogenation activity of the catalyst. This catalyst showed better catalytic activity than that of Pt-Sn/Zn-Al-O, which has been employed in a commercial process and has been reported as an excellent catalyst in dehydrogenation reactions. We claim that we have developed a novel dehydrogenation catalyst system, Pt-Sn/Fe2O3-Al2O3, which has better catalytic properties than the reported commercial catalyst.

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► Dehydrogenation of isobutane was remarkably improved by the addition of Fe2O3 to Pt/Al2O3.
► Formation of Pt-Fe particles increased the electron density of Pt, as revealed by FT-IR of CO.
► Addition of Fe2O3 inhibited sintering of supported Pt particles.
► Pt-Sn/Fe2O3-Al2O3 is a novel and excellent dehydrogenation catalyst system.