Caesium calcination

T. W. Richards and W. B. Meldrum made highly purified lithium chloride by repeatedly evaporating the purified nitrate is with an excess of hydrochloric acid in a quartz dish, and then fusing the product in an atm. of hydrogen chloride. The chlorides of potassium, rubidium, and caesium have also been purified by precipitating with hydrochloroplatinic acid, calcining the alkali chloroplatinate, and extracting the chloride with water. 

The preparation of rubidium and caesinm carbonates.—Bunsen made rubidium carbonate by treating rubidium sulphate with barium hydroxide, and evaporating the filtrate to dryness with ammonium carbonate, when crystals of the carbonate separate. R. Bunsen also transformed rubidium chloride into carbonate by first heating the chloride with nitric acid to convert it into the nitrate, and then treating the latter with an excess of oxalic acid. The oxalate is converted to carbonate by calcination. H. L. Wells made csesium carbonate by L. Snoith s process, viz, by evaporating to dryness a mixture of csesium nitrate with twice as much oxalic acid, dissolved in a little water, and calcining the residue in a platinum crucible. Caesium carbonate forms a syrupy liquid which crystallizes with difficulty. 

Surface Superbasic Sites of One-electron Donor Character. - The reaction of alkali metal with anionic vacancies on the oxide surfaces (equation 1) leads to the creation of colour centres of F type. The transfer of one electron from the alkali metal atom to an anionic vacancy is the reason for the formation of these defects. The largest quantities of this type of active centre are obtained by evaporation of the alkali metal onto an oxide surface calcined at about 1023 K, at which temperature the largest quantity of anionic vacancies is formed. Oxide surfaces calcined at such high temperatures contain only a small quantity of OH groups ca. 0.5 OH per 100 for MgO and 0.8 OH per 100 for AI2O3), so their role in the reaction is small and the action of alkali metal leads selectively to the creation of defects of the electron in anionic vacancy type. The evidence for such a reaction mechanism is the occurrence of specific colours in the oxide. Magnesium oxide after deposition by evaporation of sodium, potassium, or a caesium turns blue, alumina after sodium evaporation becomes a navy blue in colour, and silica after sodium evaporation becomes violet-brown in colour. ... 

Fischer s experiments with iron catalysts promoted with alkalies showed that they increased in efficiency with the strength of the base, with the exception of caesium. Working with catalysts prepared by calcining steel turnings with potassium hydroxide, Frolich and Lewis 1J7 showed that with a gas containing 40 per cent carbon monoxide passed into the reactor at a space velocity of 1250 at 200 atmospheres and 325° to 335° C. the best yields were obtained when the base comprised 2.2 per cent of the catalysts (calculated as K20). From this it appears that a strong base present in small amount with iron as the catalyst enables the best yields of liquid products to be obtained. This conclusion has been confirmed by the work of Audibert and Raineau. 

Basic zeolites were prepared by in situ formation of caesium oxide by calcination of the parent acetate loaded in an increasing amount up to 26 caesium atoms per unit cell. X-ray diffraction and BET studies are consistent with good crystallinity and site accessibility retainings. CO2 TPD results show homogeneous location of the basic species inside the pores with one caesium oxide per supercage. The results are fairly correlated with the initial rates of the Knoevenagel reaction of benzaldehyde and ethylcyanoacetate. These basic solids provide well-adapted selective microporous catalysts for condensation reaction. 

The slurry was stirred at room temperature until water was evaporated and then dried at 80°C for 12 h. The occluded caesium oxide was formed during the calcination (550°C) by decomposition of the corresponding acetate (330 C)... 

The impregnation of caesium acetate followed by calcination at 550°C does not affect the host faujasite crystanillity as deduced from X-ray results. Moreover, the adsorption isotherms of the modified and the parent zeolites... 

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