Organic ion exchangers with enhanced catalytic activity

1982 ◽  
Vol 47 (6) ◽  
pp. 1613-1620
Author(s):  
Zdeněk Prokop ◽  
Karel Setínek
Keyword(s):  
Catalytic Activity ◽  
Functional Groups ◽  
Ion Exchanger ◽  
Ion Exchangers ◽  
Styrene Divinylbenzene

Several methods aimed at increasing the catalytic activity of the sulphonated styrene-divinylbenzene macroporous ion exchanger Wofatit OK 80 have been tested. The activity of the prepared ion exchanger catalysts has been examined in three reactions of different type which allowed to examine the effect of the methods used in the broader range of conditions. The results obtained show that the catalytic activity of ion exchangers can be increased substantially either by increasing the total number of acid functional groups, or, particularly, by such treatment which makes the maximal number of the present functional groups accessible to reaction components. However, by the chemical procedures used to enhance the activity, the ion exchangers acquire frequently also some properties which affect negatively their application as catalysts.

Polymer structure and catalytic activity of ion exchangers

1981 ◽  
Vol 46 (7) ◽  
pp. 1577-1587 ◽  
Author(s):  
Karel Jeřábek
Keyword(s):  
Catalytic Activity ◽  
Ethyl Acetate ◽  
Active Sites ◽  
Crosslinking Agent ◽  
Reaction Medium ◽  
Polymer Structure ◽  
Local Concentration ◽  
Ion Exchangers ◽  
Styrene Divinylbenzene ◽  
Kinetics Of

Catalytic activity of ion exchangers prepared by partial sulphonation of styrene-divinylbenzene copolymers in reesterifications of ethyl acetate by methanol and propanol, hydrolysis of ethyl acetate and in synthesis of bisphenol A has been compared with data on polymer structure of these catalysts and with distribution of the crosslinking agent, divinylbenzene, calculated from literature data on kinetics of copolymerisation of styrene with divinylbenzene. It was found that the polymer structure of ion exchangers influences catalytic activity predominantly by changing the local concentration of acid active sites. The results obtained indicated that the effect of transport phenomena on the rate of catalytic reactions does not depend on the degree of swelling of the ion exchangers in reaction medium but it is mainly dependent on the relative affinity of reaction components to the acid groups or to the polymer skeleton.

Sorption of Cadmium and Lead by Chelating Ion Exchangers Ostsorb DITHIZON and Ostsorb SALICYL

1994 ◽  
Vol 59 (6) ◽  
pp. 1319-1325 ◽  
Author(s):  
Ladislav Svoboda ◽  
Stanislav Jech
Keyword(s):  
Salicylic Acid ◽  
Ionic Strength ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Exchange Capacity ◽  
Ion Exchanger ◽  
Alkaline Media ◽  
Ion Exchangers ◽  
Metal Concentrations ◽  
Cadmium And Lead

The pH and I (ionic strength) dependences of exchange capacity of chelating ion exchangers Ostsorb based on spherical cellulose modified with functional groups of dithizone and salicylic acid have been studied in the sorption of Pb(II) and Cd(II) ions. The cellulosic selective sorbents Ostsorb DITHIZON and Ostsorb SALICYL can be used for sorption of Pb(II) and Cd(II) ions from aqueous solutions of I = 0 - 1 mol l-1 (Pb) and I = 0 - 5 mol l-1 (Cd); the dithizone ion exchanger retains both metals most effectively at pH 7 - 8, the salicyl ion exchanger at pH 5.5 - 6.5 (Pb) or pH 4 - 9 (Cd). Because of the formation of precipitates of hydrolytic products of the two metals in neutral and alkaline media, it is suitable to carry out the sorption in media of mild acidity if possible, particularly so at the metal concentrations above 1 mg l-1. Increasing ionic strength affects the exchange capacity for both metals in a negative way.

Effect of Crosslinking Time on Ion Exchange Capacity of Polystyrene Nanofiber Ion Exchangers

2012 ◽  
Vol 506 ◽  
pp. 437-440 ◽  
Author(s):  
T. Nitanan ◽  
Prasert Akkaramongkolporn ◽  
Theerasak Rojanarata ◽  
Tanasait Ngawhirunpat ◽  
Praneet Opanasopit
Keyword(s):  
Sulfuric Acid ◽  
Controlled Release ◽  
Ion Exchange ◽  
Cation Exchange ◽  
Functional Groups ◽  
Crosslinking Agent ◽  
Exchange Capacity ◽  
Ion Exchanger ◽  
Ion Exchangers ◽  
Ion Exchange Capacity

In this study, polystyrene nanofiber ion exchangers (PSNIE) were successfully prepared by a new method comprising of electrospinning and the subsequent crosslinking with formaldehyde and sulfonation in sulfuric acid to create the cation exchange functionality on the fibers surfaces. The PS solution at 15% w/v in dimethylacetamide (DMAc) produced the smallest PS nanofibers (399±38 nm) with good performance. The degree of crosslink and ion exchange capacity (IEC) of PSNIE depended upon the crosslinking time. The longer crosslinking time caused the greater crosslinked PS fibers. At the longest crosslinking time of 75 min, the remaining crosslinked PS fibers in dichloromethane were 94.12%; whereas, the starting fibers completely dissolved. This crosslinking agent (e.g. formaldehyde) might introduce methylene bridges in addition to sulfone bridges into the fibers. However, IEC decreased as crosslinking time increased, probably due to the difficulty of sulfonic functional groups to react with crosslinked PS fibers. The PSNIE crosslinked for 10 min showed the maximum IEC of 2.86 meq/g-dry-PSNIE, and the diameter of the PSNIE after sulfonation increased to 450-460 nm. Since cationic drug could be loaded onto this novel PSNIE, this nanofiber ion exchanger may be applied for controlled release delivery.

Multipurpose filters with ion-exchanger for the equalization of ammonia peaks

1995 ◽  
Vol 32 (7) ◽  
pp. 199-206 ◽  
Author(s):  
Martin Oldenburg ◽  
Ivan Sekoulov
Keyword(s):  
Operation Time ◽  
Ion Exchanger ◽  
Filter Medium ◽  
Nitrification Rate ◽  
Ion Exchangers ◽  
Flow Rates ◽  
Hydraulic Loading ◽  
Influent Concentration

In this study the use of zeolites as ion-exchangers for equalization of ammonia peak loadings in aerated biological activated filters was investigated. For this use zeolites were mixed with a filter medium and the nitrifying filter was loaded with ammonia peaks for two hours at different flow rates. It could be demonstrated that during the phase of higher inflow concentrations the zeolite was collecting ammonia. When the influent concentration decreased ammonia was desorbed from the zeolite and could be nitrified by the bacteria growing on the filter medium. It was shown that additional zeolites can equalize variations of ammonia, especially in filter units which are working at a high nitrification rate and which are very sensitive to varying influent conditions. During the operation time of the filter no separation of the zeolite by higher hydraulic loading or by backwashing could be recognized. So the upgrading of nitrifying filters with zeolite represents an additional security for effluents containing oscillating ammonia concentrations.

Styrene-divinylbenzene polymer oxidation catalyst

1981 ◽  
Vol 46 (11) ◽  
pp. 2657-2662
Author(s):  
Zdeněk Prokop ◽  
Karel Setínek
Keyword(s):  
Functional Groups ◽  
Noble Metal ◽  
Additional Data ◽  
Catalytic Properties ◽  
Metal Catalysts ◽  
Oxidation Catalyst ◽  
Noble Metal Catalysts ◽  
Polymer Catalyst ◽  
Styrene Divinylbenzene ◽  
Polymer Oxidation

Some additional data about properties and applicability of a styrene-divinylbenzene polymer catalyst containing acidic and redox functional groups are reported. It is shown that the catalysts of this type can be prepared reproducibly and exhibit catalytic properties comparable to the properties of noble metal catalysts.

Polymer oxidation catalyst containing acidic functional groups

1981 ◽  
Vol 46 (5) ◽  
pp. 1237-1247
Author(s):  
Zdeněk Prokop ◽  
Karel Setínek
Keyword(s):  
Functional Groups ◽  
Elevated Temperatures ◽  
Redox Properties ◽  
Oxidation Catalyst ◽  
Carbon Clusters ◽  
Oxidation Activity ◽  
Redox Sites ◽  
Styrene Divinylbenzene ◽  
Proportional Decrease ◽  
Polymer Oxidation

The catalyst containing redox sites in addition to acid functional groups was prepared by sulphonation of a macroporous chloromethylated styrene-divinylbenzene copolymer with concentrated sulphuric acid at elevated temperatures. Its activity was tested for the oxidation of 2-propanol by molecular oxygen at 120 °C and was found to be comparable to that of the iridium on carbon catalyst.Neutralisation of acid functional groups by alkali metal led to proportional decrease in the oxidation activity. The results of EPR spectroscopic study of these catalysts show that the redox properties of the polymer are caused by carbon clusters which are capable of electron exchange.

The effect of partial exchange of sulphonated macroporous styrene-divinylbenzene copolymers for different ions on their catalytic activity

1981 ◽  
Vol 46 (10) ◽  
pp. 2354-2363 ◽  
Author(s):  
Svatomír Kmošták ◽  
Karel Setínek
Keyword(s):  
Catalytic Activity ◽  
Transition Metal ◽  
Metal Ions ◽  
Gas Phase ◽  
Transition Metal Ions ◽  
Exchange Capacity ◽  
Total Exchange Capacity ◽  
Styrene Divinylbenzene ◽  
Na Ions ◽  
Type Of Transition

The catalytic activity of sulphonated macroporous styrene-divinylbenzene copolymers, the exchange capacity of which was neutralized from 30, 50 and 80% by Fe(III) ions and from 30% by Na ions and that of Wofatit Y-37 ion exchanger neutralized from 10% of its total exchange capacity by several transition metal ions and by sodium has been studied in isomerisation of cyclohexene and dehydration of 1-propanol in the gas phase at 130 °C. It was demonstrated that in both reactions transition metal ions exhibit additional effect to the expected neutralization of the polymer acid groups. In the case of cyclohexene isomerization, this effect depends on the degree of crosslinking of polymer mass of the catalyst. Such dependence has not been, however, observed in dehydration of 1-propanol. The type of transition metal ions did not exhibit any significant effect on the catalytic activity of the polymer catalysts studied.

Sorption of Lead by the Selective Ion Exchanger Ostsorb DETA

1992 ◽  
Vol 57 (7) ◽  
pp. 1393-1404 ◽  
Author(s):  
Ladislav Svoboda ◽  
Jan Uhlíř ◽  
Zdeněk Uhlíř
Keyword(s):  
Phosphoric Acid ◽  
Aqueous Solutions ◽  
Functional Groups ◽  
Ion Exchanger ◽  
Preconcentration Procedure ◽  
Bead Cellulose

The properties of Ostsorb DETA, a selective ion exchanger based on modified bead cellulose with chemically bonded diethylenetriamine functional groups, were studied, and its applicability to the preconcentration of trace amounts of lead from aqueous solutions was verified. The conditions of the preconcentration procedure in the column and batch modes were optimized for this purpose. The results obtained were applied to the determination of lead in phosphoric acid.

RhNPs supported on N-functionalized mesoporous silica: effect on catalyst stabilization and catalytic activity

2021 ◽  
Author(s):  
Israel T. Pulido-Díaz ◽  
Alejandro Serrano-Maldonado ◽  
Carlos César López-Suárez ◽  
Pedro A. Méndez-Ocampo ◽  
Benjamín Portales-Martínez ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Mesoporous Silica ◽  
Functional Groups ◽  
Hydrogenation Catalysts ◽  
Functionalized Mesoporous Silica ◽  
Catalyst Stabilization ◽  
Shape And Size

RhNPs supported on mesoporous silica functionalized with nicotinamide groups provided active hydrogenation catalysts for several functional groups, wherein the shape and size of the RhNPs are maintained after catalysis.

Formazans as functional groups of chelating ion-exchangers

1983 ◽  
Vol 316 (2) ◽  
pp. 247-252 ◽  
Author(s):  
M. Grote ◽  
A. Schwalk ◽  
U. Hüppe ◽  
A. Kettrup
Keyword(s):  
Functional Groups ◽  
Ion Exchangers
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