Computational designing of gradient type catalytic membrane: application to the conversion of methanol to ethylene

We have developed a unique zeolite membrane with a combination of hydrophilic entrance and hydrophobic exit using computer simulation methodology. Based on the Si/Al ratio, a gradient type membrane reactor was designed in terms of stability and its capability to adsorption, diffusion process. A combination of Si/Al 300 (hydrophobic) and Si/Al 30 (hydrophilic) was found to be the best match in terms of percentage mismatch as well as binding energy. The adsorption and diffusion regarding the conversion of methanol to ethylene was examined on the resultant gradient type membrane. Depending on the Si/Al ratio a significant difference in the adsorption isotherm and diffusion behaviour of methanol and ethylene molecule was observed. Methanol was adsorbed selectively at high Al content part of the membrane reactor whereas ethylene passed easily without getting adsorbed independent to the Si/Al ratio. A plausible mechanism was proposed to justify the product formation and separation on the newly designed membrane material.