Vapor-phase adsorption isotherms of methyl tertiary butyl ether in silicalite-1 at 298 to 600K were determined (table 45) by using gravimetric analysis. A maximum saturation loading of 4mol/unit-cell was measured. The diffusion coefficients, as a function of loading at each temperature, were calculated from differential adsorption up-take data. The diffusivities increased with loading up to about 1mol/unit-cell; attributed to significant adsorption on the external surfaces of the particles. Above this value, the diffusivities became independent of loading. Grand canonical Monte Carlo and molecular dynamics simulations were used to estimate the adsorption isotherms and diffusion coefficients. The Monte Carlo simulation results were in reasonable agreement with experimental data; especially at higher pressures and lower temperatures, where the contribution of interparticle and surface adsorption became marginal. From the dynamics simulations, the molecules were seen to move very slowly within the crystal since they spent time at the channel intersections. The simulations were extended to loadings higher than 4mol/unit-cell in order to explore on the higher adsorption capacities from aqueous solutions. The mobility of the molecules was observed to increase with loading beyond the value of 4mol/unit-cell.

MTBE Adsorption and Diffusion in Silicalite-1. M.G.Ahunbay, O.Karvan, A.Erdem-Şenatalar: Microporous and Mesoporous Materials, 2008, 115[1–2], 93–7