Expanded graphite as a type of hydrophobic
functional carbon material
was innovatively selected as support for Fe-based Fischer–Tropsch
catalysts. Through catalytic activity evaluation, ferric ammonium
citrate was selected as the most suitable iron precursor for expanded
graphite among ferric nitrate, ferric ammonium oxalate, ferric citrate,
and ferric ammonium citrate. The catalyst with ferric ammonium citrate
as the precursor and expanded graphite as support achieved the best
CO2 hydrogenation performance with a CO2 conversion
rate of 42.4%, a C2
–C4
yield of 14.8%, and a CO selectivity of 8.3%.
Furthermore, it was observed that the precursor that had better wettability
and formed hydrogen bonds with support tended to generate smaller
iron nanoparticles. In addition, nitrogen doping during catalyst calcination
would cause differences in electronic properties and then influence
the reducibility and carbonization of iron species.