Nafion NR50 beads

To overcome the disadvantage of the low surface area (< 0.02 m g ) of pure Nafion NR50 beads, researchers at DuPont developed Nafion-silica composites, in which small (20-60 nm) Nafion resin particles are embedded in a porous silica matrix [7]. The composites, available under the trade name SAC 13 (containing 13 % (w/w) Nafion) are prepared by a sol-gel technique. Because of the higher surface area and accessibility of the active sites the application of this material as a solid-acid catalyst has become attractive. 

Nafion is commercially available as Nafion NR50 (DuPont) in the form of relatively large (2-3 mm) beads. A disadvantage of these beads is the low surface area (typically < 0.02 m g ) [8]. Water-selective Perma Pure membranes also consist of the polymer Nafion and were especially developed for removal of water from gas-phase streams [9]. Nafion is also available as a 5 % solution in a mixture of lower aliphatie alcohols and water [10]. 

Different alkylation reactions have been investigated with Nafion as a catalyst. An example is the propylation of benzene to cumene. Large rate enhancements were observed on use of Nafion-silica composites, compared with bulk polymeric catalysts such as pure Nafion NR50 and Amberlyst-15. The activity of the composite was ca 6-7 times higher than that of pure Nafion beads on the basis of the total amount of catalyst. If this correlation were made on the basis of the total number of acid sites on Nafion, the activity would be ca 50 times higher. Amberlyst-15 was about twice as active as the Nafion NR50 particles (on the basis of the total amount of catalyst) [7]. 

Related Reagents. p-Toluenesulfonic Acid Amberlyst 15 (20-60 mesh beads) Amberllte IR-120 (8% cross-linked beads) Dowex 50 (2% cross-linked mesh (dry) 50-100 mesh beads) Nafion-H NR50 (10-35 mesh beads 97% purity). 

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