Water-tolerant catalysis of a silica composite of a sulfonic acid resin, Aciplex

Abstract

A silica composite of a perfluorocarbonsulfonic acid resin, Aciplex, has been used as a solid acid catalyst for a variety of reactions concerning water. The Aciplex–SiO 2 composite containing 20 wt% Aciplex has a surface area of 1.3 m 2 g −1 and possesses an ion-exchanged capacity of 0.46 meq. g −1 after pretreatment at 423 K, which is higher than that of 13 wt% Nafion–SiO 2 (0.12 meq. g −1). The acid strengths estimated from an initial heat of adsorption of NH 3 were similar for these polymer resin composites. It was found that the Aciplex–SiO 2 was more active than typical solid acids such as Cs 2.5H 0.5PW 12O 40, H-ZSM-5, and SO 4 2−/ZrO 2 for hydrolysis of ethyl acetate in excess water and esterification of acrylic acid with 1-butanol, while it was less active than Cs 2.5H 0.5PW 12O 40 for N-alkylation of acrylonitrile with 1-adamantanol and solid–solid hydrolysis of 2-naphthyl acetate. The Aciplex–SiO 2 was superior in activity to Nafion–SiO 2 for all the above reactions and in thermal stability. These results indicate that Aciplex–SiO 2 is a promising solid acid catalyst for reactions involving liquid phase water.