Promoting Propane Dehydrogenation with CO2over the PtFe Bimetallic Catalyst by Eliminating the Non-selective Fe(0) Phase

Fine tuning the structure of bimetallic nanoparticlesis critical toward understanding structure-activity relationshipsand further improving the catalytic performance in propanedehydrogenation (PDH). Excessive Fe species in the PtFebimetallic catalysts promote carbon deposition leading to lowpropylene selectivity, and it remains challenging to synthesize well-defined PtFe catalysts while selectively eliminating the excessive Fe.Herein, we show that the formation of coke can be significantlyinhibited by introducing CO2into the PDH over PtFe catalysts,where CO2effectively eliminates the active Fe(0) coking siteswithout changing the catalytic surface structure of the PtFe alloy.With a CO2/C3H8feeding ratio of 0.20, the Pt1Fe7/S-1 catalystshows the highest propylene production rate and decreasedamount of coke from 18.8 to 1.0 wt % compared with dehydrogenation without CO2. X-ray absorption spectroscopy, X-rayphotoelectron spectroscopy, and57Fe Mo??ssbauer results indicate that it is the oxidation of excessive unalloyed Fe species during theCO2-PDH reaction, instead of the reverse Boudouard reaction (CO2+ C = 2CO), that significantly inhibits the carbon deposition.This work provides a promising strategy for tuning the structure of PtFe bimetallic catalysts under reaction conditions and improvingthe performance of the PDH reaction.