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Mechanistic Modeling of Cobalt Based Catalyst Sintering in a Fixed Bed Reactor under Different Conditions of Fischer–Tropsch Synthesis
journal contribution
posted on 2012-09-19, 00:00 authored by Majid Sadeqzadeh, Jingping Hong, Pascal Fongarland, Daniel Curulla-Ferré, Francis Luck, Jacques Bousquet, Daniel Schweich, Andrei Y. KhodakovA three-step sintering mechanism is proposed for Co-based
catalysts
under Fischer–Tropsch reaction conditions. This mechanism includes
an intermediate formation of oxide layer on cobalt metal nanoparticles
in the presence of water. The partially reversibly oxidized surface
accelerates sintering by both reducing the surface energy and enhancing
the diffusion rates of cobalt particles. The proposed mechanism is
then employed for a fixed-bed unsteady state reactor. The effect of
particle growth on the catalytic activity was analyzed within a diverse
range of operating conditions (syngas ratio = 1.5–4, water
co-feed ratio = 0–6, inert co-feed ratio = 0–6). It
is found that, at the same gas space velocity, sintering proceeds
faster at higher H2/CO ratios. At the same initial conversion,
a low H2/CO syngas ratio increases sintering severity,
i.e., catalyst deactivation due to the crystallite growth, as it brings
about higher relative water partial pressure. Dilution of syngas with
different amounts of inert gas does not affect the cobalt sintering
rate. Cobalt sintering proceeds more rapidly if water is co-fed during
the reaction.
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crystallite growthsintering mechanismCatalyst SinteringBed ReactorMechanistic Modelingcobalt particlesDifferent Conditionsdiffusion ratessintering proceedsparticle growthoxide layercobalt sintering ratestate reactorsyngas ratiogas space velocitycobalt metal nanoparticlesCobalt sintering proceedssurface energy
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