Acidic Exchange Resin Research Articles

Sulfonic acid ion-exchange resins as catalysts in nonpolar media: II. Influence of conditioning methods on the acidity and catalytic activity

The behaviour of macroporous sulfonated styrene-divinylbenzene copolymers has been investigated in relation to their acidity and catalytic efficiency in the alkylation of benzene with propene. In order to optimize catalyst activity, the following separate parameters have to be taken into account: Adsorbed water lowers the catalytic activity, but after an induction period the poisoning effect of water is at least partially offset by the interaction of the sulfonic acid groups with the olefin. The optimal drying temperature is 100°C; higher temperatures cause a sharp decrease in catalyst acidity and therefore lower catalyst activity. In addition, the perfusion of the dried resin with benzene can produce a considerable decrease in catalyst activity. The deactivation caused by elevated drying temperatures and by interaction with benzene is discussed in terms of their effect on the flexibility of the polymer backbone.

Sulfonic acid ion-exchange resins as catalysts in nonpolar media: I. Drying of the catalyst

The retention of adsorbed water upon drying of sulfonated macroporous styrene-divinylbenzene copolymers in vacuo was investigated gravimetrically and by Karl Fischer titration. The residual water content θ w decreased with increasing degree of crosslinking and was related quantitatively to the temperature, pressure and duration of drying. The increase of the drying temperature was limited with respect to the thermal stability of the resins, and the reduction of θ w was effective only down to certain values θ w . θ w was found to depend on the degree of proton exchange by K + and Ca 2+ in different ways and to decrease in the sequence La 3+ ≈ Ca 2+ > H + > K +.

Relation between homogeneous acid catalysis and ion exchange resins using a test reaction

The kinetic analysis of the depolymerization of trioxane with a strong acid resin supplied as commercial catalyst has been performed. Experiments at different speeds of rotation lead to the conclusion that the external mass transfer is not the controlling step, and the influence of the temperature on the reaction rate indicates the chemical reaction as controlling step. A relation between the resin load and the Hammett acidity function can be obtained after comparison between the homogeneous catalyzed reaction and the resin catalyzed reaction. This relation seems to be useful in order to establish an equivalence between catalytic resins and homogeneous catalyzed reactions for practical purposes. Two parameters, ϱ, which describes the quantitative relation between acidity and resin concentration and Δ E/R, which takes account of the small difference between activation energies in homogeneous acid catalysis and heterogeneous acid (ion exchange) catalysis are able to describe the feasibility to use acid resins in homogeneous acid catalyzed reactions. The studied system seems to have an application as a test reaction for the evaluation of catalytic resins.

Hydration of 2-methylbutenes on organic ion exchange resin catalysts

The course of the hydration of a mixture of 2-methyl-1-butene and 2-methyl-2-butene in dependence on the structure of strongly acidic styrene-divinylbenzene ion exchange resin catalysts has been studied. The most efficient catalysts turned out to be macroporous ones. The reaction rate increased with increasing temperature, while the amount of the product (2-methyl-2-butanol) in the equilibrium reaction mixture decreased. Similarly, the hydration was strongly affected by the water to alkene molar ratio in the starting reaction mixture. Modification of ion exchange resin catalysts with 1-butylamine did not affect course of the hydration in the case of gel type catalysts, while with macroporous resin catalysts the addition of amine up to 0.5% of the total catalyst exchange capacity showed activating effect.

Dissolution of Hydroxyapatite in Water Containing a Strongly Acidic Ion Exchange Resin and Its Analysis

Dissolution of Hydroxyapatite in Water Containing a Strongly Acidic Ion Exchange Resin and Its Analysis

ChemInform Abstract: Alkylation of Furan and Thiophene with tert‐Butanol in the Presence of the Strong Acid Cation Exchanger Amberlyst 15.

AbstractFuran (I) und Thiophen (V) lassen sich mit tert.‐Butanol in Gegenwart molarer Mengen (bez.

A modification of the mechanism of formation of methyl galactosides by the Fischer reaction including a computer simulation

The Fischer reaction of d-galactose and methanol, catalyzed by a strongly acidic ion-exchange resin, to form the four methyl galactosides has been run at two temperatures under conditions that allow a computer simulation of the mechanism. The reaction was followed by gas-liquid chromatography of the trimethylsilyl ethers. The data obtained differs appreciably from that described in a previous paper [ J. Org. Chem., 38 (1973) 3272–3277)] owing to an error in peak assignment in that paper. The mechanism previously proposed, however, has required only a slight modification to explain the new data. A possible set of rate constants, equilibrium constants, and apparent activation energies which fit the experimental data have been obtained.

Methyl t-Butyl Ether (MTBE) Production: A Comparison of Montmorillonite-Derived Catalysts with an Ion-Exchange Resin

AbstractMontmorillonite-based catalysts were compared with an acidic ion-exchange resin of the type used industrially for the production of methyl t-butyl ether (MTBE) from methanol and isobutene or t-butanol. When 1,4-dioxan was used as solvent, Al3+-exchanged montmorillonites had about half the efficiency of the resin Amberlyst 15 at 60°C; they were, however, about twice as efficient at this temperature at Ti3+-montmorillonite or K10, a commercially available acid-treated bentonite. Montmorillonite exchanged with Chlorhydrol solutions to give interlayer [Al13O4(OH)2(H2O)12]7+ ions and pillared clays derived from such materials were poor catalysts, as was K306, a more drastically acid-treated bentonite- based commercial catalyst. Freeze-drying of the Al3+-clay before reaction to produce a more open, porous structure had no effect on its catalytic efficiency. The activation energy for the reaction of isobutene and methanol in dioxan was 44 kj/mole for an Al3+-clay catalyst compared with 25 kJ/mole for reactions catalyzed by Amberlyst 15. With no solvent (as in industrial processes), the rates of reaction were considerably slower for both the clay- and resin-catalyzed reactions. As has been found previously for resin-catalyzed reactions using stoichiometric amounts or an excess of methanol, the rate was proportional to the isobutene concentration, and the rate-determining step appeared to be protonation of the alkene. The performance of the Al3+-clay catalyst was increased by reducing the water content of the clay. In most reactions the clay catalysts were equilibrated at 12% relative humidity. Exposure of the clay to a low vacuum (10−1 torr) before use increased its catalytic activity from 50 to 60% of that of Amberlyst 15.

Heteropolyacids and their salts supported on acidic ion-exchange resin as highly active solid-acid catalysts

Heteropolyacids and their salts supported on a macroreticular acidic ion-exchange resin, Amberlyst-15, show much higher activity than Amberlyst-15 itself, and those supported on activated carbon, celite, silica or titanium dioxide for the hydration of 2-methylpropene and the esterification of acetic acid with 1-pentanol. The higher activity may plausibly be attributed to the interaction of heteropoly anions with substrates which are protonated by the protons of the acidic resin.

Synthesis and application of bifunctional phosphinic acid ion exchange resins

Synthesis and application of bifunctional phosphinic acid ion exchange resins

Measurement of acidity of polymeric solid acids

Acidity measurements using Hammett indicators have been applied to macroporous sulfonic acid ion-exchange resins in nonpolar media. The acidity was varied by partial ion-exchange. It has been proven that the adsorption of the indicator molecules is reversible in the case of a thermally pretreated resin. From the measurement of the adsorption data, the ionization ratio of the indicators can be calculated and correlated to the reactivity in the alkylation of benzene with propene and to the degree of ion-exchange. Using these correlations, a relative acidity scale can be defined. The accessibility of acid groups in different solvents must be determined as a prerequisite for the application of the theory developed in this study.

Solubility of BaSO<sub>4</sub> Powders in Water Containing a Strong Acidic Ion Exchange Resin

In our previous study, it was found that BaSO4 powders, a sparingly soluble salt, was able to dissolve in water suspended with a strong acidic ion exchange resin (abbreviated as H-R). This paper presents a method to elucidate the surface activity of BaSO4 powders which are heat-treated up to 800°C. Some factors responsible for the dissolution tendency of BaSO4 such as H-R/H2O ratio, soaking temperature and the amount of H-R were examined to determine the optimum condition. The average particle diameter was compared with an electron microscope. A remarkable change in solubility was observed for the BaSO4 powders calcined at 450°-500°C without any significant change in particle size. Calcination at higher temperatures resulted in a slight increase in solubility in spite of the enhanced grain growth.

Kinetics and equilibria of the hydration of linear butenes over a strong acid ion-exchange resin as catalyst

The hydration of 1-butene (B), cis-2-butene (C) and trans-2-butene (T) to 2-butanol (A) catalysed by a strong acid ion-exchange resin (XE-307) was studied in the temperature range of 75–150°C. Kinetic experiments were performed by passing aqueous solutions of these butenes or 2-butanol through a resin bed (particle size 0.6–0.7 mm) of known capacity at a constant flow rate. Besides hydration, isomerization of the three butenes takes place. The experimental results can be explained by assuming that all reactions proceed via the sec-butyl carbenium ion as reactive intermediate. The reactions involved are equilibrium reactions. Numerical values of the rate constants of the various reactions and the equilibrium constants have been determined. The overall equilibrium constant of the hydration reaction of the butenes in the liquid phase is considerably less favourable than in the corresponding hydration of propene. The rate constants for butene hydration are of a similar order of magnitude to those for propene hydration. When resin particles of 0.65 mm diameter are used, the rate of reaction is found to be affected by intraparticle diffusion limitations at temperatures above 115°C.

Isolation of Aroma-Bearing Material from Lactobacillus helveticus Culture and Cheese

In whey permeate supplemented with amino acids and inoculated with Lactobacillus helveticus, methionine was necessary for good aroma development. The aroma of Lactobacillus helveticus cultures could be removed by passing the culture fluid through either acid or basic ion-exchange resins. When the ion-exchange resins were eluted with appropriate volatile acid or base and the eluates were evaporated, the residues slowly generated volatile aroma compounds. Several acetamides were identified in culture extracts. The culture eluates from acid ion-exchange resins were fractionated into a caramelized-burned and a cereal-like component. The burned component was a complex of carbonyls with amino acids, and the burned flavor was attributed to 2,5-dimethyl-4-hydroxy-3[2H] furanone. The cereal component contained a number of volatile amines among which pyr-rolidine had the greatest aroma impact. Various pyrazines, indole, and skatole also were identified. Aqueous cheese extracts yielded aroma-bearing fractions that behaved like the culture aromas on ion-exchange chromatography. The cheese extracts contained aromas with the same gas chromatographic retention times as those in the cultures.

Heteropoly Acids Supported on Acidic Ion-exchange Resin as Highly Active Solid-acid Catalysts

Abstract Heteropoly acids supported on a macroreticular acidic ion-exchange resin shows much higher activity than those supported on activated carbon for the synthesis of methyl t-butyl ether and the esterification of acetic acid with 1-pentanol. This high activity can plausibly be attributed to the interaction of heteropoly anions with substrates which are protonated by the protons of the acidic resin.

Separation of lead and copper on a series of chelating ion-exchange resins. Part I

The physico-chemical and chelating properties of aromatic poly(hydroxamic acid) ion-exchange resins are described. The resins are used for the quantitative separation of the heavy metals lead and copper, which are often present in industrial effluents. These resins show excellent kinetic characteristics for copper and lead ions. The effect of metal concentration on the cation-exchange capacity is also reported. Even after 20 loading-acid washing cycles the resins show greater stability than the hydroxamic acid resins reported earlier. Quantitative separation of the two metals is achieved by using different eluting reagents.

Regeneration of a magnetic carboxylic ion exchanger with recoverable complexing agents

The use of EDTA sodium salts (Na 2H 2Y, Na 3HY and Na 4Y; EDTA is denoted here by H 4Y for regeneration of weakly acidic magnetic graft ion-exchange resins has been studied. The process consists of stripping heavy metal ions from the resin by a solution containing the EDTA sodium salt, followed by acidification of the regeneration effluent with mineral acid to precipitate the EDTA as the free acid. The EDTA is then separated and converted to a suitable sodium salt (Na 2H 2Y, Na 3HY or Na 4Y) by redissolution in aqueous NaOH or Na 2CO 3. The recovered EDTA sodium salt is reused for regeneration. The regeneration effluent, after precipitation of the EDTA, is neutralized with Ca(OH) 2 to precipitate the heavy metal as its hydroxide, which is then separated. The cost of chemicals consumed in the process was evaluated for the particular case of cadmium. Chemical costs seem reasonable, alkali for redissolution being the largest item. The most likely application of the method appears to be in heavy metal removal from sewage or sewage sludge, but other possibilities have been identified.

Kinetics and equilibria of the hydration of propene over a strong acid ion exchange resin as catalyst

The kinetics and equilibria of the direct hydration of propene over a strong acid ion exchange resin (C8P ex AKZO) were studied. The experiments were c

Polymerization of benzyl alcohol and its derived compounds with an ion exchange resin

Benzyl alcohol, benzyl chloride and dibenzyl ether polymerize in certain conditions in the presence of ion exchange resins in the H+ form to give a polymer of the general formula (C6H4CH2)n. Independently of the reactant, this result allows to establish reaction mechanism based solely on the acid-base equilibrium in the Bronsted or Lewis meaning and independently of the catalyst type: sulfuric acid, stannic chloride or ion exchange resin.

Preparation and evaluation of ion exchange resin-immobilized rhodium-phosphine hydroformylation catalysts

Insoluble analogs of homogeneous rhodium hydroformylation catalysts are obtained by ionic attachment of a functionalized phosphine onto an ion exchange resin, and subsequent ligand exchange with a soluble rhodium complex. Both acidic and basic ion exchange resins can be used for ligand insolubilization. Supported rhodium complexes exhibit superior reactivity for hydroformylation of 1-octene, and low losses of rhodium by metal leaching.