Relations between texture and transport properties in the primary pore system of catalyst supports

Porous glasses in shape of beads and flat membranes with controlled mesoporosity in the range between 2 and 20 nm were used as model system to study the correlation between the texture properties and the transport characteristics in the primary pore system of catalyst supports. The beads and membranes were distinguished by comparable texture parameters. The tortuosity factors of the pore structure were obtained from measurements of the permeability of nitrogen of the porous glass membranes. The tortuosity factors vary in the range between 1.5 and 40 depending on the pore diameter and the porosity of the membranes. The hydrogenation of benzene over nickel catalysts based on the porous glass beads was used as test reaction. Here, the effective mesopore diffusivities were obtained from the Arrhenius plots. Furthermore, the pore diffusion coefficients of benzene were determined. The values are in the range between 1 × 10−6 and 2 × 10−5 cm2 s−1. A systematic correlation between the texture properties (mean pore size) and transport characteristics (pore diffusion coefficient) was observed.