Influence of H2 on the Oxygen-Assisted Dehydrogenation of Ethane over Al2O3-supported Pt-Sn Catalysts

The oxygen-assisted dehydrogenation of ethane at 650 A degrees C shows that adding Sn to the Pt catalyst results in increased conversion and selectivity to ethylene. Even the smallest amount of tin (0.16 wt%) has a significant effect. The addition of tin also increases the stability of the Pt/Al2O3 catalyst, in particular it reduces the amount of carbon or carbonaceous species. Adding hydrogen to the feed had a remarkable effect on the selectivity, but the conversion of ethane was almost unaffected for Pt-Sn catalysts. The selectivity to ethylene increased substantially and the selectivity to CO/CO2 decreased even for the smallest amount of tin used. Unexpected values for the selectivity to other compounds were also observed, in particular for the selectivity to acetylene. The importance of possible Pt-Sn alloys or the necessity of contact between Pt and Sn was studied using a physical mixture of Pt/Al2O3 and Sn/Al2O3. However, almost the same effect was obtained by using the physical mixture as with the co-impregnated sample, i.e. the Pt-Sn catalysts. Selectivity of ethylene for the monometallic catalyst, the physical mixture and the coimpregnated catalyst. [GRAPHICS] .