Comprehensive kinetic model for acetylene pretreated mesoporous silica supported bimetallic Co-Ni catalyst during Fischer-Trospch synthesis

A new model by incorporating the porosity field during acetylene pretreatment (PT) into the Fischer-Trospch (FT) synthesis comprehensive kinetic is proposed for quantitatively describing the product distributions using a mesoporous silica supported Co-Ni bimetallic catalyst. Coupling the quasi-homogeneous medium model with the acetylene reaction kinetics via the Langmuir-Hinshelwood-Hougen-Watson (LHHW) approach, the model yields good predictions for breakthrough curves, pressure drops, and permeability during PT process. The active carbidic intermediates formed by the acetylene PT engaged with the subsequent CO dissociation and 1-olefin re-adsorption associated secondary reactions during FT synthesis. The constructed comprehensive kinetic model can predict the olefin to paraffin ratios (OPR) versus chain length when the catalyst was pretreated. A relatively good prediction from chain length dependent model (CLD) indicates the validity of assuming that Van Waals forces play a critical role during olefin re-adsorption in the secondary reactions for chain propagations once the mesoporous supported Co-Ni bimetallic catalyst was pretreated by acetylene. The proposed model successfully bridges the gaps between the PT and FT process at the investigated experimental conditions.