Studies of the fischer‐tropsch synthesis on a cobalt catalyst II. Kinetics of carbon monoxide conversion to methane and to higher hydrocarbons

Abstract

Six Langmuir-Hinshelwood-Hougen-Watson models have been derived for the kinetics of conversion of carbon monoxide to hydrocarbons in the Fischer-Tropsch synthesis. The models were fitted to experimental data obtained in an internal recycle reactor over a wide range of operating conditions. Two models, one based on the hydrogenation of surface carbon and the other on a hydrogen-assisted dissociation of carbon monoxide as rate limiting steps were both able to provide a satisfactory fit to the experimental rate data.A general model was also developed for the rate of methanation in the presence of higher hydrocarbons. The same two rate limiting assumptions as those used in formulating the rate of total CO conversion are used in these models. The two models were fitted to experimental data for methane formation.It was the model assuming CH formation as rate limiting that showed the best fit for both CO conversion for CH, formation.Six modkles Langmuir-Hinshelwood-Hougen-Watson ont CtC calculCs pour la cinetique de conversion de l'oxyde de carbone en hydrocarbures dans le procCdC Fischer-Tropsch. Ces modeles ont CtC adapt& 2 des donnCes exPCrimentales obtenues dans un rCacteur de recirculation interne sur une large gamme de conditions operatoires. Deux modkles, I'un base sur I'hydrogenation du carbone de surface, I'autre sur une dissociation par I'hydrogkne de I'oxyde de carbone servant pour la limitation des vitesses, ont permis de caler de manikre satisfaisante les donnCes de vitesse exptkimentales.Un mo&le gCnCral a Cgalement CtC dCveloppC pour la vitesse de mkthanation en prCsence d'hydrocarbures supkrieurs. On a utilisC dans ces deux modkles les m&mes hypotheses de limitation des vitesses qui ont servi dans la formulation de la vitesse de la conversion totale de CO. Ces deux modkles ont CtC adaptCs aux donnCes expirimentales pour la formation de mfthane.C'est le modkle supposant la formation de CH comme limitation des vitesses qui correspond le mieux B la conversion de CO et h la formation de CH,.

Development of the Fischer-Tropsch Process: From the Reaction Concept to the Process Book

“…The aim of this new kinetic model is to be able to predict selectivity (paraffin and olefin distributions) forvarious operating conditions (pressure, temperature, GHSV (Gas Hourly Space Velocity) and H 2 /CO). The new simulator is able to plug both kinetic models: -one based on Sarup and Wojciechowski (1989) description for CO conversion with an imposed selectivity for paraffins and olefins using an Anderson-Schultz-Flory distribution; Relative rate of fines formation for three different catalysts, as obtained in the Sannazzaro slurry bubble column pilot plant and in the LVT.…”

“…The kinetic rate has the same formalism as the kinetic model developed by Sarup and Wojciechowski (1989), which considers a rate-determining step (first hydrogen addition to carbon). Alcohol selectivities are determined using an Anderson-Schultz-Flory distribution adjusting a corresponding chain length growth parameter.…”

Reactor Modeling of a Slurry Bubble Column for Fischer-Tropsch Synthesis

“…There are many kinetic models in the literature (Yates and Satterfield, 1991;Sarup et al, 1989). It appears that the kinetic rate follows the SarupWojciechowski kinetic model.…”

C1 Chemistry for the Production of Ultra-Clean Liquid Transportation Fuels and Hydrogen

“…and .CH 2 .) and water (OH) since they are not occupying a significant part of the active sites and their desorption rate is much higher than the other species 4,15 . Based on the previous assumptions, eq.…”

“…For the elimination of the infinite sum in eq 5, we assumed that at steady state the initiation rate of the polymerization process should balance its termination rate 5,15 . Therefore, a mass balance around the methyl (CH 3 .S or R1) initiation rate (3rd reaction in stage 3) and termination rate (to methane stage 4 or paraffins as included in stage 5) is sufficient for the determination of the infinite sum as seen in eq 6.…”