Acids continued zirconium

Dialkylaminoethyl acryhc esters are readily prepared by transesterification of the corresponding dialkylaminoethanol (102,103). Catalysts include strong acids and tetraalkyl titanates for higher alkyl esters and titanates, sodium phenoxides, magnesium alkoxides, and dialkyitin oxides, as well as titanium and zirconium chelates, for the preparation of functional esters. Because of loss of catalyst activity during the reaction, incremental or continuous additions may be required to maintain an adequate reaction rate. 

Early waterproofing treatments consisted of coatings of a continuous layer impenetrable by water. Later water-repellent fabrics permitted air and moisture passage to improve the comfort of the wearer. Aluminum and zirconium salts of fatty acids, siUcone polymers, and perfluoro compounds are apphed to synthetic as well as natural fibers. An increase in the contact angle of water on the surface of the fiber results in an increase in water repeUency. Hydrophobic fibers exhibit higher contact angles than ceUulosics but may stiU require a finish (142). 

In the same year Jones and Cunningham continued these experiments (2) and found that the cerium and the berkelium adsorption on zirconium phenylarsonate carrier were similar regardless of the oxidizing agent (bichromate, chlorate, hypochlorite, or bromate), or the medium (IN nitric acid, IM lithium perchlorate-perchloric acid at hydrogen ion... 

Thermogravimetry indicated a continuous weight loss of the sulfated sihca supported zirconia of only about 3 %. The thermogravimetric data on the catafysts prepared by reaction of zirconia with suUuric acid were more informative (see also ref. [12]). When the temperature was raised with 10 K/min, the catalyst prepared by reaction with calcined zirconia showed a much more smooth weight loss, which set on already at about 350 K. Apparently, it is much more difficuh to remove the constituents of sulfuric acid out of the much more porous structure of the zirconium hydroxide. 

The trimethylsilylated silicic acids formed in this instance are soluble in conventional organic solvents, and their volatility is sufficiently high for them to be analysed by gas chromatography. Carzo and Hoebbel [411] carried out a comprehensive study of the chromatographic retention of various trimethylsilylated silicic acids on different stationary phases Apiezon L and silicone OV-1 and OV-17. The analysis of metals in the form of volatile complexes continues to attract attention, and have been described for analysing sodium [412], potassium [412], radium [413], caesium [413], barium [414], calcium [414], strontium [415], beryllium [416, 417], magnesium [418], zinc [419, 420], nickel [419], mercury [421], copper [422, 423], silver [424, 425], cadmium [421], indium [426, 427], g ium [428], scandium [217], cobalt [421], thallium [426], hafnium [429, 430], lead [431, 432], titanium [430], vanadium [433], chromium [434-436], manganese [426], iron [437], yttrium [438], platinum [439,440], palladium [439, 441, 442], zirconium [430], molybdenum [443], ruthenium [444], rhodium [445], rare earths [446—449], thorium [221, 450, 451] and uranium [221, 452]. The literature on GC analysis of metal chelates was reviewed by Sokolov [458]. 

Separation of chromic acid residues from the oxidation product is carried out continuously today by a disk separator. Zirconium is the only construction material that can be considered in view of the highly corrosive properties of the medium. A disk separator of zirconium has been developed specifically for this purpose in cooperation with an engineering company. This gives both an improvement in product quality by reducing the chromium content of the oxidation product and a saving of sulfuric acid for the washing processes. The sodium sulfate content of the wastewater is thus reduced by 13 kg per tonne of acid wax. 

An alternative continuous process extracts only the zirconium into 2 5 volumes of solvent from an 8N nitric acid feed, using four extraction stages. This has associated six stages of stripping with 0 5 volumes of 5N nitric acid. The extraction section aqueous acidity is about 5-2N. The zirconium is recovered by backwashing the loaded solvent with an equal volume of water, in a single stage. 

For zirconium equipment, it is very important to maintain acid concentration within the limits indicated in Figure 22.8. When the limit is exceeded, zirconium may corrode rapidly. In <65% H2SO4, the vapor phase is almost entirely water. However, the concentration change is negligible when a system is under a pressurized condition. Add concentration may change significantly when, for example, the system is imperfectly sealed. In a leaking system, the acid concentration can exceed the concentration limit. Acid concentration can easily increase when the system is under vacuum operation because water vapor is continuously taken away. 

Dehydrogenation activities of the oxides of selenium and tellurium were observed by the pulse technique.Thus, the zirconium oxides which are loaded with selenic acid or telluric acid and calcined in air can dehydrogenate 2-propanol to acetone and hexane to benzene.In a typical reaction of 2-propanol, the conversion into acetone decreases continuously after the third pulse, probably owing to a decrease in the amount of oxygen on the catalyst surface. Poisoning experiments with injection of CO2, H2O or butylamine at 523 K before reaction had no effect on the yield of acetone. Thus this dehydrogenation process appears to be an oxidative dehydrogenation. No studies on the acidic or basic character of oxides of selenium and tellurium oxides have been reported. 

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