Co/Pillared Clay Bifunctional Catalyst for Controlling the Product Distribution of Fischer-Tropsch Synthesis

Pillared interlayer clays (PILCs) were synthesized by pillaring montmorillonite with SiO2, Al2O3, and ZrO2, and Co-supported PILCs were prepared by the impregnation method. For comparison, Co/SiO2 and Co-supported montmorillonite treated with dilute FINO3 (acid-clay) were also prepared. The materials were characterized by XRD, H-2-TPR, NH3-TPD, O-2 titration, and N-2 adsorption-desorption. The Co-supported catalysts were comparatively investigated for Fischer-Tropsch (FT) synthesis in a fixed-bed reactor under the conditions of I MPa, 508 K, H-2/CO = 2, and W/F = 5.02 g center dot h center dot mol(-1). The results indicate that the activities of the catalysts (i.e., CO conversions) increase in the order of Co/Na-Clay << Co/Si-PILC approximate to Co/acid-clay Co/Al-PILC < Co/Zr-PILC Co/SiO2. Moreover, Co/PILCs can effectively narrow the product distribution of FT synthesis showing significantly increased C-5-C-12 selectivity and much decreased C21+ selectivity. The results are well explained based on the acidic properties of the PILCs together with the textural properties, pore size distributions, and reduction behaviors of the catalysts.