Acidity deterioration and coke deposition on Iron- Zeolite Catalyst in Fischer – Tropsch Synthesis

Considerable effort has been devoted in resent years to the investigation of bifunctional catalysts for the conversion of synthesis gas to selected product states, especially gasoline range hydrocarbons. The interest arises from the fact that the catalytic conversions of syngas to hydrocarbons over Fischer – Tropsch (FT) catalysts such as Fe and Co doesnot make liquid fuels with sufficient selectivity. The HZSM-5 supported iron catalyst have been investigated with respect to physical and chemical properties and to activity and product selectivity for conversion of syngas to hydrocarbon products. The catalyst preparation consisted of physical admixture of precipitated iron oxide with HZSM-5. Fe/Cu catalyst with different promoters consists of CaO, MgO and La2O3 was prepared by copercipitation technique and was added to HZSM-5 catalysts and then, mixed thoroughly with binders like Silica- Zirconium, Silica-titanium and Silica-Alumina and shaped to cylinders. Catalyst activity study was carried out in a fixed bed stainless still reactor at 290 oC, 17bar; H2/CO=1, GHSV=3.07 nl (g.Fe.h)-1 for time on stream 250 h. The acidity deterioration of the HZSM-5 from the iron - zeolite catalyst has been related to coke deposition. The effect of promoters and binders on coke deposition and acidity deterioration of the HZSM-5 has been studied from experiments in a fixed-bed reactor.