Development of a Macro Kinetic Expression for the Iron-based Low-Temperature Fischer-Tropsch Synthesis

Development of a Macro Kinetic Expression for the Iron-based Low-Temperature Fischer-Tropsch Synthesis

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Part of #Development of a Macro Kinetic Expression for the Iron-based Low-Temperature Fischer-Tropsch Synthesis# :

Publishing year : 2011

Conference : 7th National Congress of Chemical Engineering

Number of pages : 10

Abstract: In this experimental study, a kinetic model has been developed for Fischer-Tropsch synthesis reactions using Fe / Ni / Al2O3 as a catalyst (40% Fe / 60% Ce / 40wt% Al2O3) in a fixed bed micro reactor Assuming no internal or external diffusion. Operating conditions of the reactor are as follows: reactor total pressure 1-12 atm; Temperature 220-260 C; H2 / CO feed ratio 1-2 and space velocity 4200 hr-1. Considering the mechanism of the process and the Langmuir-Hinshelwood-Hogan-Watson (LHHW) approach, for the CO consumption flow equations were defined four different mechanisms, namely, karbide, enol, combined karbideenol and parallel carbon-enol. The kinetic data of this study are fitted fairly well by a simple form r = AP 0.5 P / (1 + k P + kP) 2CO H 2 COCO COH 2 OH 2 similar to that suggested by Botes. The obtained rate expressions for the COhydrogenation reactions from the nonlinear regression analysis and the Levenberg-Marquardt method demonstrate that the formation of monomer species (HCOs) due to CO hydrogenation reaction has controlled the FTS reaction rate. The activation energy and adsorption enthalpy toward CO and H2O were calculated as 78.58 kJ / mol and -30.56 kJ / mol and 30.94 respectively.