Alumina activity

ALUMDJUMCOPTPOUNDS - ALUMINIUMOXIDE(ALUMINA) - ACTIVATED] (Vol 2) [ALUMDJUMCOPTPOUNDS - ALUMINIUMOXIDE(ALUMINA) - HYDRATED] (Vol 2)... 

Amorphous siHca gel, activated alumina, activated carbon, and molecular sieve carbons. 

Diphenylamine can also be produced by passing the vapors of aniline over a catalyst such as alumina, or alumina impregnated with ammonium fluoride (17). The reaction is carried out at 480°C and about 700 kPa (7 atm). Conversion per pass, expressed as parts diphenylamine per 100 parts of reactor effluent, is low (18—22%), and the unconverted aniline must be recycled. Other catalysts disclosed for the vapor-phase process are alumina modified with boron trifluoride (18), and alumina activated with boric acid or boric anhydride (19). 

Alumina is used because it is relatively inert and provides the high surface area needed to efftciendy disperse the expensive active catalytic components. However, no one alumina phase possesses the thermal, physical, and chemical properties ideal for the perfect activated coating layer. A great deal of research has been carried out in search of modifications that can make one or more of the alumina crystalline phases more suitable. Eor instance, components such as ceria, baria, lanthana, or 2irconia are added to enhance the thermal characteristics of the alumina. Eigure 6 shows the thermal performance of an alumina-activated coating material. 

The amount of alumina needed dejjends upon the color of the benzene solution. Sufficient alumina (activated alumina, 80 mesh, from Aluminum Corporation of America) is taken so that the filtrate is only light yellow in color. On the larger scale only 100-200 g. of alumina was needed. 

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