Design of supported cobalt catalysts with maximum activity for the Fischer–Tropsch synthesis

A Highly Active and Selective Manganese Oxide Promoted Cobalt-on-Silica Fischer–Tropsch Catalyst

“…This shows the beneficial impact of NC on the Co 3 O 4 crystallite size, which is in line with previous findings [5,6,31].…”

“…For the CoPt/SiO 2 catalysts (no MnO present) the activity difference between NC and AC treatments is limited, and smaller than reported before [6]. Clearly, the reduction temperature applied (550 8C) is not optimal for the NC catalyst and reduction at 450°C has been used before [6].…”

“…Moreover, this relatively high activity of the MnO promoted catalyst is obtained for Co particle sizes (*4 nm) smaller than the optimum particle size (*5 nm) [6], and hence a significantly lower activity was expected. This might indicate that the MnO promoted catalysts do not show a cobalt particle size effect identical to that of unpromoted catalyst [6], possibly caused by a different Co surface structure or particle shape. However, it might also indicate that manganese oxide acts both as selectivity and activity promoter [32], thereby boosting the performance of small Co particles.…”

“…Clearly, the reduction temperature applied (550 8C) is not optimal for the NC catalyst and reduction at 450°C has been used before [6]. For the NC catalyst reduced at 550 8C it can be concluded that the addition of MnO up to Mn/Co = 0.08 brings about an increase of both activity (Fig.…”

“…[1][2][3][4] A recent example of improving the catalytic activity using this methodology is provided in a previous contribution from our laboratory, where a cobalt-on-silica catalyst was synthesized by an impregnation and drying step, followed by calcination of cobalt nitrate precursor in a flow of NO/He [5,6]. This method yielded a surfaceweighted cobalt particle size of *5 nm with a narrow particle size distribution.…”