Exchange impregnation

Most zeolite-containing products require multiple manufacturing steps, including further chemical transformation, modification, ion exchange, impregnation, forming, drying and calcination, prior to their application as adsorbents or catalysts. Selected manipulations are detailed in the next sections. 

For practical (real) catalyst systems, precipitation, ion exchange, impregnation and sol-gel processing procedures are used. In precipitation methods, a hydroxide or a carbonate of a metal may be precipitated from a solution of a metal salt onto the support material held in the solution. Thus, a copper-silica catalyst may be prepared using a Cu-nitrate solution in which silica is suspended. Additives of any alkali cause the precipitation of copper hydroxide onto the silica support. This is then dried and normally reduced in hydrogen at moderate temperatures ( 400-500 °C) to form the catalyst. In co-precipitation techniques , the support is precipitated simultaneously with the active catalyst. In the ion-exchange method, for example, highly dispersed Pt on... 

When a support is put in a solution containing a precursor of the active component, several phenomena can occur among which ion exchange, impregnation, dissolution of the support and formation of surface compounds are the most important. If the experimental parameters are not properly adjusted, there is a fair probability that these phenomena may occur simultaneously. In what follows, we shall therefore discuss, for the sake of simplicity, first ion exchange and then impregnation. We will then consider the problem of oxide dissolution. 

Shrigadi, N. B., A. B. Shinde, and S. D. Samant. 2003. Study of catalytic activity of free and KlO-supported iron oxyhydroxides and oxides in the Friedel-Crafts benzylation reaction using benzyl chloride/alcohol to understand their role in the catalysis by the Fe-exchanged/impregnated K10 catalysts. Appl. Catal. A 252 23-25. 

Traces of phosphate were concentrated on a cation-exchanger impregnated with Fe(III) [12,13] or with barium chloranilate [14]. Mixtures of P(V), As(V), and Si(IV) were separated on an anion-exchange column [15]. 

Table 3. Static and MAS-NMR data for hydrated, dehydrated and partly ddiydrated samples (Cs-NaX (exchanged) and Cs20/CsNaX (exchang + impregnated) from ref. 66.

Heat exchangers Impregnated graphite reinforced vSth carbon fiber as Diabon (S ), Bigiior, Graphilor BS (Le Carbone-Lofr e). ... 

In addition to their microporous environment, zeolites offer a range of other important chemical properties. They are highly acidic materials. One can time both the number of acid sites and the strength of these sites and thus control their overall acidity. They have high thermal stabilities. Metal ions can be readily exchanged, impregnated or added into the synthesis to open up many other types of reactions. 

A survey of literature on the TLC separation of synthetic dyes indicated that little attention has been paid to the separation of dyes on impregnated plates. Only a few papers have appeared in the area in the last many years. Two types of impregnated layers have been used to separate the synthetic dyes, metal ion-impregnated plates and ion exchanger-impregnated plates. 

TLC of dyes on ion exchanger-impregnated plates, 1021-1023 ITLC (instant TLC) +/- silica, 925... 

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