Synthesis and Application of Monolithic Ion Exchange Resin

Abstract

We have developed a new type monolithic ion exchange resin which has a co-continuous porous structure, and we have been applying it for water treatment and for synthetic catalyst use. The pore structure was obtained by a two-step polymerization process. In the first step, an open-celled porous styrene-divinylbenzene copolymer was synthesized by preparation of water-in-oil (W/O) emulsion followed by polymerization. In the second step, the obtained copolymer was soaked and polymerized in a solution containing styrene, divinylbenzene, and a polymeric initiator. In order to obtain the monolithic ion exchange resin, functional groups, such as sulfonic acid and trimethylammonium, were introduced into the copolymer. The ion exchange capacity of both monolithic cation exchange resin (CEMR) and anion exchange resin (AEMR) were over 4 meq/g. The ion exchange band length of the monolithic ion exchange resins were approximately 10 times shorter than that of conventional ion exchange resin columns. Pd-supported AEMR (Pd/AEMR) was able to decompose hydrogen peroxide generated in the ultrapure water production line efficiently, and the treatment flow rate could be raised to approximately 10 times that of the Pd-supported cation exchange resin (Pd/CEMR). Pd/AEMR showed catalytic activity in hydrogenation reactions and coupling reactions, and in the continuous flow hydrogenation reaction using Pd/AEMR, higher yield was obtained in a shorter time than in batch reaction.