Diffusion of methane in mesoporous silica

Methane diffusion in a sufficiently large silica particle has been investigated experimentally by the diffusion cell technique in pulse and saturation modes. The measurements have been performed by varying the experimental temperature and methane amount. The kinetic curves have been found to follow the simple model of intra-particle diffusion. The measured effective diffusivity is in the order of 10-7 m2/s. The activation energy of methane diffusion obtained in the pulse mode equals 14 +/- 1 kJ/mol, whereas the saturation experiment gives the activation energy identical to 21 +/- 1 kJ/mol. These values are consistent with the published data obtained by adsorption experiments and molecular dynamic simulations. The heat of methane adsorption on silica is in the range of 14-16 kJ/mol. The observed kinetics reflects the intra-particle diffusion-controlled desorption.

Automated summary

Methane diffusion in large silica particles was experimentally investigated using the diffusion cell technique in pulse and saturation modes. The measured effective diffusivity was found to be in the order of 10-7 m2/s. The activation energy of methane diffusion obtained in pulse mode was 14 +/- 1 kJ/mol, while the saturation experiment gave an activation energy identical to 21 +/- 1 kJ/mol. These values are consistent with published data from adsorption experiments and molecular dynamic simulations. The observed kinetics reflects intra-particle diffusion-controlled desorption.