Platinum-tin and platinum-copper catalysts for autothermal oxidative dehydrogenation of ethane to ethylene

The addition of various metals to Pt-coated ceramic foam monoliths was examined for the autothermal oxidative dehydrogenation of ethane to ethylene at similar to 900 degrees C at contact times of similar to 5 ms. The addition of Sn or Cu to Pt-monoliths enhanced both C2H6 conversions and C2H4 selectivities significantly, giving higher C2H4 yields. No deactivation or volatilization of the catalysts was observed. For Pt-Sn, an increase in the Sn/Pt ratio from 1/1 to 7/1 increased both the conversion and the selectivity. For Pt-Sn (Sn/Pt = 7/1) versus Pt alone the conversion increased by up to 6% and the selectivity up to 5% for an increase in optimal yield from 54.5% with Pt to 58.5% with Pt-Sn. XRD and XPS measurements showed that Pt existed in the form of PtSn and Pt3Sn alloys. The 1/1 Pt-Cu catalyst showed comparable performance, with conversion increasing by 5% and selectivity by 3%. The addition of several other metals to Pt-monoliths decreased both C2H6 conversion and C2H4 selectivity in the order, Sn > Cu > Pt alone> Ag > Mg > Ce > Ni > La > Co. For oxidative dehydrogenation of n-butane and isobutane, Pt-Sn and Pt-Cu also showed higher conversion than Pt.