Copper-modified alumina as a support for iron Fischer–Tropsch synthesis catalysts Original Research Article

In the present study, the effect of Cu-modified Al2O3 on the properties of Al2O3-supported Fe catalysts in the Fischer–Tropsch synthesis was investigated. Ten weight percent Cu was first impregnated into γ-alumina to produce Cu-modified Al2O3 supports; then 20 wt.% of Fe and (in some cases) 1 wt.% Cu were added to the supports by the sequential impregnation method. Two different pretreatment methods (drying or drying and calcining) were employed after each metal impregnation. It was found that the use of Cu-modified Al2O3 supports increased significantly the overall activity of the Fe/Al2O3 catalysts. Addition of 1% Cu as a reduction promoter to the Cu-modified supported Fe catalysts was not necessary since it did not further enhance the activity of the catalysts. There were no changes in FT product selectivity, chain growth probability (α), or olefin selectivity due to any effect of the Cu-modified Al2O3 or Cu-promotion. However, the more calcination steps used during preparation, the higher the catalyst activity obtained. Cu-modification of the alumina most probably diminished the interaction/reaction of the Fe with the support, thereby improving its chemisorption and catalytic properties.