Lewatit

Lewatit is a trademark of Bayer Corporation Purolite is a trademark of Purolite International Resintech Is a trademark of Resintech, Inc. 

This argument is confirmed by the study of CO pulse chemisorption by Biffis at al., mentioned above. In this piece of investigation, the authors prepared a 2% (w/w) palladium catalyst supported by Lewatit UCP 118, a macroreticular resin (nominal cld = 18 %) from Bayer. Its TEM characterization showed a remarkably heterogeneous distribution of the metal nanoclusters, which are apparently located close to the surface of the polymer nodules [62] (Figure 9). 

Figure 9. Distribution of palladium nanoclusters in a M°/CFP catalyst based on the macroreticular resin Lewatit UCP 118. (Reprinted from Ref [62], 2000, with permission from Elsevier.)...

Cation-exchange resins are used as catalysts in the produdion of MTBE (methyl tertiary-butyl ether, 2-methoxy-2-methylpropane) and various other oxygenates and, lately, also in the dimerization of isobutene [30]. Other commercial applications of the cation-exchange resins indude dehydration of alcohols, alkylation of phenols, condensation readions, alkene hydration, purification of phenol, ester hydrolysis and other reactions [31]. The major producers of ion-exchange resins are Sybron Chemicals Incorporated [32] (Lewatit resins), Dow Chemical Company [33] (DOWEX resins), Purolite [28] (Purolite resins), and Rohm and Haas Company [27] (Amberlyst resins). 

Sydron Chemicals Inc., Chemical and Environmental Ion Exchange Products (Lewatit ion exchange resins product data sheet), http //www.ion-exchange.com/ service/ pdf chem. env.pdf, 20 August 2006. 

Lewatit SPS 118 is a strongly acidic ion exchange resin. - Yield over two steps, n. r. = not reported... 

Mixtures of organic solvent and water have also been studied (Scheme 11). hi this context, Watanabe and coworkers studied the catalytic dehydration of fructose to HMF at 150°C in acetone-water mixtures and in the presence of a cation-exchange resin catalyst (Dowex 50wx8-100) [92]. The use of acetone-water (70 30 w/w) as reaction medium resulted in a yield of HMF of 73% at 94% conversion. Moreover, under these conditions, the catalyst was stable for at least five catalytic runs. Assistance of microwave not only increased the selectivity to HMF but also had a beneficial effect on the reaction rate. In this context, Gaset et al. studied the activity of Lewatit SPC-108 (cation-exchange resin) in a mixture of organic solvent (MIBK or diethyl ketone or benzonitrile or butyronitrile or dichlor-oethylether or nitropropane) and water (from 1/7 to 1/12 by volume) at a temperature around 85-90°C Under these conditions, HMF has been obtained with a yield of 70-80% [93, 94]. 

Inglezakis et al. (2003) studied the removal of Pb2+ (500 ppm) in a batch system using the chelating resin Lewatit TP-207, under rigorous agitation (650 rpm) and ambient temperature (30 °C). The ion-exchange process is followed by an irreversible reaction in the resin phase, represented by the following scheme ... 

Using a surface-sulfonated ion exchange resin (refs. 11-12), optimum accessibility of the active groups which are almost exclusively located at the inner surface of the microparticles is attained. The measured reaction rate (see Table 1) is about ten times higher than that of the identically cross-linked Lewatit SPC 11B. 

The checkers used analytical grade AG 50W-X8 resin, which is a strongly acidic polystyrene gel type resin, supplied by Bio-Rad Laboratories. The submitters used the large-pore, strongly acidic ion-exchange resin Lewatit SPC 118, supplied by Bayer AG. 

In the fourth step anhydride 18 is opened to succinamidic acid 19 by the introduction of ammonia, and this is again cyclized to give succinimide 5 via the mixed anhydride from 19 and acetyl chloride 1 EtOH, Lewatit S 100, CHCfi, reflux, 95%. 

Fe(lll)-loaded chelating resin (Lewatit TP 207) Laboratory solutions 20 1.7 As(V)... 

As common examples of monomers used for the production of resins, methacrylate and styrene can be mentioned, where the cross-linkers are ethylene dimethacrylate (EDMA) or divinyl benzene (DVB), respectively [205], The most important resins of this type are the poly(styrene-divinyl benzene) type or Amberlite resins, as well as the Wofatit and Lewatit [192] types. These materials have been widely applied as adsorbents [191,192,207] and as ion exchangers [193,194,208],... 

Polystyrenes cross-linked with divinylbenzene commercial resins, such as Lewatit VP-OC 1163 (Bayer AG, Leverkusen, Germany), Amberlite XAD-4 (Rohm Haas, Frankfurt, Germany), and Serdolite PAD I, PAD II, and PAD III (Serva AG, Heidelberg, Germany), have been applied in the adsorption of phenol, chlorophenols, and dihydroxybenzenes from water solutions [90]. Besides, commercial polymethacrylate/divinylbenzene resins, for example, Supelcogel TPR-100... 

Ion-exchange polymeric resins are the most important types of exchangers currently in use [113-123], The first, totally organic ion-exchange resin was synthesized in 1935 by Adams and Holmer, when they produced a phenol-formaldehyde cation-exchange resin and an amine-formaldehyde anion-exchange resin, both obtained with the help of condensation polymerization reactions [113], In 1944, D Alelio synthesized styrene-based polymeric resins, which could be modified to obtain both cationic- and anionic-exchange resins. The majority of the resins commercially applied currently are of this type, for example, Amberlite IR-20, Lewatit S-100, Permutit Q, Duolite, C-20, Dowex-50, and Nalcite HCR. 

---