Microwave assisted synthesis of MCM-41 and diffusion of organic solvents in porous media

Abstract

Microwave assisted synthesis of mesoporous molecular sieves is a promising method due to several advantageous over conventional hydrothermal method such as more uniform heating, homogeneous nucleation and shorter crystallization times. The effect of microwave power and synthesis time on the structure of MCM-41 were discussed using XRD, N2 physisorption, SEM, TEM techniques. The optimum reaction time and microwave power was determined after the trial of several combinations. The obtained products were compared with the ones synthesized by hydrothermal method. MCM-41 obtained from microwave assisted synthesis was used in the diffusion experiments of organic solvents. The diffusion coefficients, mode of transport and activation energies of organic solvents into the porous channels of MCM-41 were investigated in 24-28 ˚C temperature range. As the molecular weight of the organic solvents increased, diffusion coefficients decreased, the activation energy for diffusion increased, and the time necessary to reach equilibrium was increased.