Influence of the Precursor Composition and Reaction Conditions on Raney-Nickel Catalytic System

Abstract

Raney-Nickel is routinely used in the process of selective hydrogenation of benzene and its derivatives. In order to gain a better understanding of this catalytic reaction, we have implemented both atomistic and thermodynamic modeling methods. While modeling at the atomistic level provides essential information about structure, electronic effects and dynamics, thermodynamic modeling provides data on physical properties of the system of interest. First, we investigated the influence of the alloy composition on the Raney-Nickel catalyst structure based on a molecular dynamics (MD) based workflow. Different initial and final NiAl compositions were tested. Our simulations indicate that there is a dependence of the pore size on the NiAl composition and this is more pronounced when some Aluminum remains in the catalyst. Next, the solubility of hydrogen in benzene was calculated with thermodynamic modeling. The effect of temperature, pressure, and concentration of cyclohexane (product) on the solubility of hydrogen in benzene was examined. For a given temperature, our studies provided the optimal pressure necessary to obtain maximum solubility of hydrogen in benzene. Finally, based on the results obtained, we have studied the competitive adsorption and chemisorption of benzene and cyclohexane on Raney-Nickel as a first step towards modeling the catalytic hydrogenation of benzene.