Microporous and mesoporous aluminosilicates as catalysts for the cracking of Fischer-Tropsch waxes towards the production of "clean" bio-fuels

The potential utilization of various microporous (zeolites H-Y and H-ZSM-5) and mesoporous (amorphous silica-alumina and Al-MCM-41) aluminosilicates as catalysts or active matrices in the cracking of Fischer-Tropsch waxes towards the production of liquid fuels was the subject of this study. Focus was placed on the effect of porous and acidic characteristics of the materials on products yields and properties. Both zeolitic catalysts were very active leading however to different product selectivities. The moderately steamed H-Y catalyst produced more gasoline and less LPGs compared to the H-ZSM-5 catalyst. The relatively high gasoline RON values for both catalysts were attributed to the high yield of isoalkanes and olefins in the case of the H-Y catalyst and to the high yield of aromatics in the case of H-ZSM-5. The use of mildly acidic Al-MCM-41 type mesoporous materials resulted in relatively low wax conversion activity, while the amorphous silica-alumina catalyst was almost inactive.