Fine-tuning the structure of bimetallic nanoparticles is essential to understand structure-activity relationships and further improve catalytic performance in propane dehydrogenation (PDH). Excess Fe in PTFE bimetallic catalysts promotes carbon deposition, resulting in low propylene selectivity. However, it remains challenging to selectively eliminate excess Fe without damaging the structure of the PTFE catalyst. Recently,Guo News, Dalian University of TechnologyZhang GuanghuiwithSong Chunshan, Chinese University of Hong Konget al. demonstrated that the formation of coke could be significantly inhibited by the introduction of CO2 into PDH on the PTFE catalyst, in which CO2 effectively eliminated the active Fe(0) coking site without changing the catalytic surface structure of the PTFE alloy.
Compared with the dehydrogenation reaction without the addition of CO2, the feed ratio of CO2 C3H8 is 0At 20, the propylene yield of PT1Fe7 S-1 catalyst was the highest, and the coke content was from 188 wt% reduced to 10 wt%。Based on the understanding of the structural changes of Fe-based catalysts, Fe(0) species can be oxidized to Fe3O4 in CO2 hydrogenation reactionsThe stable FeOX species exhibits higher olefin selectivity and weaker coking capacity in PDH reactions compared to metallic iron species (although its contribution to the dehydrogenation rate is much lower than that of PTFE alloys).
The XPS, ExAFS, and 57Fe M SSBAUER results show that significant inhibition of carbon deposition is due to the oxidation of excess non-alloyed Fe species during the CO2-PDH reaction, rather than the inverse Boudouard reaction (CO2 + C = 2CO). In conclusion, the introduction of soft oxidant CO2 to oxidize the non-alloy non-selective Fe(0) phase in PTFE bimetallic catalysts to improve PDH performance provides a guiding strategy for adjusting the structure of PTFE bimetallic catalysts and improving the performance of PDH reactions under reaction conditions.
promoting propane dehydrogenation with co2 over the ptfe bimetallic catalyst by eliminating the non-selective fe(0) phase. acs catalysis, 2022. doi: 10.1021/acscatal.2c00649