Mesoporous Zeolites from Carbon Aerogel Templating

Recently many nanoporous carbons have been synthesized using templating method. On the contrary, carbons can be applied as the template, because carbon can be gasified. Zeolite molecular sieves are crystalline porous solids with intricate pore and channel systems in the molecular size range of 0.3 to ~3 nm. They are widely used in industry as heterogeneous catalysts [1]. Although micropores of zeolite are uniform, diffusion in the micropores often intervenes the chemical process [2]. A controlled reduction of the zeolite’s crystal size has been attempted as a means to solve this micropore diffusion problem [3]. However, such attempts are not necessarily successful. If we could donate uniform mesopores to zeolites, the resulting bimodal pore-structured zeolites would further extend the applications of zeolites. Recently, Jacobsen et al [4]. prepared mesoporous ZSM-5 of a wide pore size distribution of 10 to 100 nm by impregnating them with carbon black particles, and Holland et al.5 synthesized macroporous (250 nm average diameter) silicates by using arrays of monodisperse polystyrene (PS) spheres as templates. We prepared zeolite ZSM-5 monolith with a bimodal pore structure of uniform mesopores (11 nm average width) by the templating method using a carbon aerogel of uniform mesopores. Carbon aerogel is well known to have uniform mesopores [6].