Alumina standardisation

Preparation and Standardisation of Alumina. The activity of alumina depends inversely on its water content, and a sample of poorly active material can be rendered more active by leaving for some time in a round bottomed flask heated up to about 200° in an oil bath or a heating mantle while a slow stream of a dry inert gas is passed through it. Alternatively, it is heated to red heat (380-400°) in an open vessel for 4-6h with... 

The sm-face area and pore volumes of alumina samples were found to increase with increase in base to alkoxide molar ratio. Samples with ageing duration of 16 h and higher base / alkoxide, solvent ratios have mesopores whereas samples with no aging duration have only micropores. A highly distinct pore size distribution obtained for all the samples where conditions are standardised in terms of ageing duration, base / alkoxide mole ratio and IPA / water mole ratio. 

The distribution of adsorbent grain size must be standardised and air humidity and pH conditions reproducible if remission spectra are to be quantitatively evaluated. Water, for example, partly displaces the adsorbed substance molecules and thereby alters the form of the spectra [373]. Frei and co-workers [201] have investigated the reflectance spectra of some dyes adsorbed on Merck alumina, as a function of its thermal pre-treatment. They tested also the influence of neutral, acid or basic alumina on the form of the spectra. Modifications were observed due to interactions between adsorbed substance and adsorbent (chemisorption). 

ISO 902 (1976) Angle of Repose for Alumina. International Organisation for Standardisation, Geneva. 

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