Separation of CO sub(2) and N sub(2) with a lithium-modified silicalite-1 zeolite membrane

• Published in: International journal of greenhouse gas control Vol. 10; pp. 494 - 500
• Main Authors: Lara-Medina, J J, Torres-Rodriguez, M, Gutierrez-Arzaluz, M, Mugica-Alvarez, V
• Format: Journal Article
• Language: English
• Published: 01.09.2012
• ISSN: 1750-5836
• DOI: 10.1016/j.ijggc.2012.07.014

Carbon dioxide capture and storage is gaining attention as a strategy to abate greenhouse gas emissions. However, currently available commercial processes to remove CO sub(2) from flue gas streams, mainly from N sub(2) are costly and energy intensive. A silicalite-1 membrane was prepared on a porous alumina support using hydrothermal synthesis. The resulting silicalite-1 membranes were modified using Li solutions in order to achieve better CO sub(2) separation. SEM micrographs exhibited a thin, uniform and compact silicalite-1 film well adhered to the alumina support. Crystallinity of the membrane was confirmed by XRD. CO sub(2) and N sub(2) permeation experiments were carried out in a stainless steel module. CO sub(2) single gas permeation was measured through a silicalite-1 membrane from room temperature to 400 degree C, having a 25 psi pressure on the feed side. The resulting CO sub(2) permeance measurements indicated molecular sieving as the principal transport mechanism for the unmodified silicalite-1 membrane, whereas surface diffusion is the principal transport mechanism for lithium-modified silicalite-1 membranes. The separation between CO sub(2) and N sub(2) takes place due to preferential CO sub(2) adsorption and diffusion, which in turn hinders N sub(2) permeation through the silicalite-1 pore network. A CO sub(2)/N sub(2) separation factor up to 6 at 25 psi and 400 degree C was obtained using the silicalite-1 modified membrane, whereas this was 1.46 using the unmodified silicalite-1 membrane.