Catalyst acidic sulfonated cation-exchange

The conventional MTBE synthesis consists of a reaction of isobutene and methanol over an acidic sulfonated cation-exchange catalyst. This reaction is highly selective, equilibrium-limited, and exothermic in nature. Several types of industrial reactors such as tubular reactors, adiabatic reactors with recycle, and catalytic distillation configurations have been utilized to cany out the MTBE synthesis reaction. The factors considered in the optimal design of a MTBE unit include the following items [52]. 

Direct, acid catalyzed esterification of acryhc acid is the main route for the manufacture of higher alkyl esters. The most important higher alkyl acrylate is 2-ethyIhexyi acrylate prepared from the available 0x0 alcohol 2-ethyl-1-hexanol (see Alcohols, higher aliphatic). The most common catalysts are sulfuric or toluenesulfonic acid and sulfonic acid functional cation-exchange resins. Solvents are used as entraining agents for the removal of water of reaction. The product is washed with base to remove unreacted acryhc acid and catalyst and then purified by distillation. The esters are obtained in 80—90% yield and in exceUent purity. 

Direct esterification takes place in the presence of sulfmic acid or sulfonic toluene, or sulfonic cation exchange resins, at atmospheric pressure and temperatures between 20 and 120°C depending on the ester. Solvents are used to remove the water produced during the reaction. Residual acrylic arid and the catalyst are neutralized, and the acrylate purified by distillation. The total yield of the operation is up to 80 to 90 molar per cent... 

Hydrolytic co-condensation products underwent catalytic rearrangement in the presence of electrophilic catalyst presence [7-9]. Sulfonic cation-exchange resin or natural aluminosilicate-bentonite activated by mineral acid was used as this catalyst. 

Although catalytic hydration of ethylene oxide to maximize ethylene glycol production has been studied by a number of companies with numerous materials patented as catalysts, there has been no reported industrial manufacture of ethylene glycol via catalytic ethylene oxide hydrolysis. Studied catalysts include sulfonic acids, carboxyUc acids and salts, cation-exchange resins, acidic zeoHtes, haUdes, anion-exchange resins, metals, metal oxides, and metal salts (21—26). Carbon dioxide as a cocatalyst with many of the same materials has also received extensive study. 

The choice of catalyst is based primarily on economic effects and product purity requirements. More recentiy, the handling of waste associated with the choice of catalyst has become an important factor in the economic evaluation. Catalysts that produce less waste and more easily handled waste by-products are strongly preferred by alkylphenol producers. Some commonly used catalysts are sulfuric acid, boron trifluoride, aluminum phenoxide, methanesulfonic acid, toluene—xylene sulfonic acid, cationic-exchange resin, acidic clays, and modified zeoHtes. 

This acid-catalyzed cleavage of the glycosidic bonds is rather complex and often suffers from a lack of selectivity mainly due to side dehydration or recombination reactions of monosaccharides. In the existing literature, four different classes of solid catalysts are reported (1) cation-exchange resins, (2) siliceous-based materials, (3) metal oxides, and (4) sulfonated amorphous carbons. 

The formation of 0,0-acetals from carbonyl compounds and alcohols takes place according to the mechanism of Figure 9.12. As acidic catalysts one uses a mineral acid (HC1 or H2S04) or a sulfonic acid (p-toluenesulfonic acid, camphorsulfonic acid, or a strongly acidic cation exchange resin) ... 

The pioneer work in this field was carried out on polystyrene-supported acid catalysts [161]. Thereafter, several works on the use of sulfonic, strong acidic cation exchangers as acid catalysts were reported for alkylation, hydration, etherification, esterification, cleavage of ether bonds, dehydration, and aldol condensation [162,168-171], Besides, industrial applications of these materials were evaluated with reactions related to the chemistry of alkenes, that is, alkylation, isomerization, oligomerization, and acylation. [163,169], Also, Nation, an acid resin which has an acid strength equivalent to concentrated sulfuric acid, can be applied as an acid catalyst. It is used for the alkylation of aromatics with olefins in the liquid or gas phases and other reactions however, due to its low surface area, the Nation resin has relatively low catalytic activity in gas-phase reactions or liquid-phase processes where a nonpolar reactant or solvent is employed [166],... 

Liquid phase isobutane/butene-2 alkylation was conducted at 0 -60°c using a stirred-tank reactor in the presence of a catalyst comprising of a macro-reticular acid cation exchange resin and boron trifluoride. Neither BF3 nor resin alone was effective for alkylation. For the sulfonic acid resin/BF3 sys-... 

R 9. Rohm Haas Company Sulfonic acid cation exchange r in catalysts and chemical reactions involving the use thereof. Brit. Pat 956.357 (1964). 

The phenol-formaldehyde prepolymers were polymerized with 4-(l-phenylethyl)phenol (para-styrenated phenol) (equation 39). The sulfonation of the resulting polymer gave a cation exchange resin, which is useful as an acid catalyst . ... 

---