How do the preparation methods impact the kinetic parameters of the two Co/Ni/Al2O3 nanocatalysts in Fischer–Tropsch process?

Abstract

The influence of the preparation methods on the kinetics of Fischer-Tropsch (FT) synthesis in a fixed-bed reactor is investigated by kinetic tests employing two 80 %Co/20 %Ni/Al 2 O 3 catalysts prepared through: (a) cogelling support and cobalt, as well as nickel (SG), and (b) impregnating cobalt and nickel with sol-gel derived support (IM-SG). The kinetics for both the catalysts is developed on the basis of Langmuir-Hinshelwood-Hougen-Watson (LHHW) type models at the same range: T = 200-250°C, P = 1-10 bar, gas hourly space velocity (GHSV) = 4200 h -1 and H 2 /CO mole ratio of 1/1-3/1. According to the enolic and carbide mechanisms, eight kinetic expressions of the CO consumption rate have been tested. The achieved best fitted model is subject to a good correlation between experimental and theoretical data; and the kinetic parameters are estimated by the use of Levenberg-Marquardt algorithm. Kinetic parameters such as rate constant (k) and activation energy (E a ) suggest that the preparation method remarkably impact the FT behavior. The IM-SG sample was selected as the better catalyst due to a higher reaction rate and less activation energy comparing with the SG catalyst. Graphical abstract

Comprehensive kinetic study for Fischer–Tropsch reaction over KMoFe/CNTs nano‐structured catalyst

“…[ 6 ] Since the physicochemical properties of the catalyst influence the adsorption of species in the reaction, the preparation method of the catalyst impacts the kinetic parameters using the LHHW kinetic models. [ 58 ] The value of activation energy demonstrates that the FT reactions are not limited by intraparticle diffusion resistances. In general, the mass diffusion limitations play a dominant role in the enhancement of hydrocarbon selectivity through gas hourly space velocity.…”