Cobalt based hybrid Fischer-Tropsch synthesis catalyst for improved selectivity of hydrocarbons in the JP-8 carbon number range from a synthesis gas obtained from the pyrolysis of the MixAlco process derived sludge
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The synthesis gas produced from the pyrolysis of the MixAlco process [5] (which converts wastes into fuels and chemicals) has the composition of 45% H 2/35% CO together with up to about 20% CH 4. Recovery of the methane and application of steam reforming allows the adjustment of the H 2:CO ratio to about 1.9 optimum for cobalt performance in an enhanced Fischer-Tropsch synthesis (FTS) process. The performance of a new hybrid catalyst Co-SiO 2/Mo-Pd-Pt-HZSM-5 (with a metal-metal-acid functionality) was compared with that of a conventional Co-SiO 2 catalyst under the same thermodynamic condition of 10 atm and 250 C. The specific surface areas of the two catalysts were characterized using the BET technique. The electron probe microanalyzer (with WDS and EDS capabilities) was then used to confirm the presence of the applied metals Co, Mo, Pd and Pt on the respective supports. The effect of pressure was then examined on the hybrid catalyst at the temperature of 250 C and a higher pressure of 13.6 atm. At 10 atm and 250 C, the conventional FTS catalyst produced fuels rich in hydrocarbons within the gasoline (C 4-C 12) carbon number range. Hydrocarbons with carbon numbers within the JP-8 (C 8-C 17) and to some extent diesel range (C 15-C 25) were also produced. At the same condition the Co-SiO 2-Mo-Pd-Pt/HZSM-5 catalyst increased the selectivity of JP-8 carbon number range hydrocarbons. When the hybrid catalyst Co-SiO 2/Mo-Pd-Pt-HZSM-5 was examined at 13.6 atm and 250 C, a further increase in the selectivity of JP-8 carbon number range hydrocarbons and to some extent diesel was observed. The relative amounts of olefins and n-paraffins decreased with the distribution shifting towards the production of more isomers. A fixed bed continuous flow catalytic system was used. 2012 Elsevier B.V. All rights reserved.
