Abstract:
FeAl precursors (remarked as P) were prepared by co-precipitation method. Then they were impregnated with promoter Zn, K and Cu into ZnKCu/FeAl catalysts (remarked as C). The precursors and catalysts were characterized by low temperature N
2 adsorption, XRD and H2-TPR. CO
2 hydrogenation over these catalysts was investigated in a fixed-bed reactor. With the addition of Al, the specific surface area of FeAl precursors and ZnKCu/FeAl catalysts was increased relative to that of Al-free samples. On the contrary, the crystallite size of a-Fe
2O
3 was decreased by the added Al. The dispersed degree of Cu was raised in the catalysts containing Al. It is benefit for the reduction of ZnKCu/FeAl catalysts. However, the specific surface area and a -Fe
2O
3 crystallite size of P-10 and C-10, in which the Al2O3/Fe
2O
3 mass ratio is 10%, were similar to those of P-5 and C-5 with 5% Al 2O3/Fe
2O
3 mass ratio, respectively. The phenomena were resulted from the strong g-Fe
2O
3 phase in P-10 and C-10. It was evidenced that g-Fe
2O
3 was formed only in the case of Fe and Al were co-precipitated, and the precipitate was washed by anhydrous ethanol in this study. The catalyst with strong g-Fe
2O
3 phase was more active in CO
2 hydrogenation than the catalysts with none or weak g-Fe
2O
3 phase. This correlation was supported by the comparison between two catalysts with the same Al content, but different Fe
2O
3 phases in them.