Fischer–Tropsch synthesis over alumina supported cobalt catalyst: Effect of promoter addition

Abstract

In order to improve the activity of Co/Al2O3 catalyst for FT synthesis, loading effect of metal promoter on Al2O3 support was examined. In this study, total 13 kinds of metal (Mg, Ca, Sr, Ba, Y, La, Ce, Ti, V, Mn, Zn, Zr and Mo) were employed as promoters and θ-Al2O3 prepared by the calcination of commercial boehmite was used as support. Co/Al2O3 catalysts loaded with various metal promoters were prepared by a sequential impregnation method. Loading of Mn, V and Mo on Al2O3 support decreased Co reducibility and surface area of Co metal, but increased intrinsic activity per active Co metal sties (i.e. TOF). On the other hand, metal additives other than Mn, V and Mo varied Co reducibility and Co surface area, but did not influence TOF. High overall activity was obtained over Co/Al2O3 catalysts loaded with rare earth elements (e.g. La and Ce), which was due to the high surface area of Co metal. We also examined the co-loading of La and V promoters on Al2O3 support. Co/Al2O3 catalysts loaded with both La and V (Co/La+V/Al2O3) showed higher activity than those loaded with either La or V. CO conversion rate over the best Co/La(2)+V(0.5)/Al2O3 catalyst was 1.6 times as high as that over bare Co/Al2O3 catalyst. Over the Co/La+V/Al2O3 catalyst, La and V promoters cooperatively improved Co reducibility, Co surface area and TOF, resulting in an increase of overall catalytic activity.