Precipitated Fe/Cu/K Fischer鈥揟ropsch Synthesis (FTS) catalysts incorporated with precipitated and binder Al
2O
3 were characterized by N
2 physical adsorption, Temperature-Programmed Reduction/Desorption (TPR/TPD), and M枚ssbauer Effect Spectroscopy (MES). It was found that the Al
2O
3 incorporation manner plays an important role on metal dispersion and metal鈥搒upport interaction, which dramatically influence the H
2/CO adsorption, reduction, and carburization, as well as FTS performances of iron catalysts. Specifically, the incorporation of Al
2O
3 during precipitation (i.e., precipitated Al
2O
3) leads to high Fe
2O
3 dispersion and strengthens the Fe鈥揅u and Fe鈥揔 contacts, which in turn promote the reduction and increase the surface basic sites as well as H
2 and CO adsorptions. In sharp contrast, Al
2O
3 added either after precipitation or after heat treatment of the iron precursor (i.e., binder Al
2O
3) is
likely to form a strong metal鈥搒upport interaction (i.e., Fe鈥揂l
2O
3 interaction) and decrease the surface basicity, thereby inhibiting CO adsorption. Correspondingly, in slurry-phase FTS reaction, it was observed that the addition of precipitated Al
2O
3 faci
litates catalyst carburization and improves the FTS activity. As expected with the presence of binder Al
2O
3, the reduced catalysts contain small amounts of iron carbides and show low FTS activity as well as water gas shift (WGS) reactivity. Further, presumably because of more basic sites than binder Al
2O
3 supported catalysts, the catalyst incorporated with precipitated Al
2O
3 shows lower selectivity to
light hydrocarbons (methane, C
2鈥揅
4, C
5鈥揅
11, and C
12鈥揅
18) but remarkably higher selectivity to heavy hydrocarbons (C
19+). These observations were explained in terms of the influence of the Al
2O
3 incorporation manner on the promotional effects of Cu and K.
Keywords:
Fischer鈭扵ropsch synthesis; iron catalyst; precipitated Al2O3; binder Al2O3; metal dispersion; metal-support interaction