Abstract
The surface areas of amorphous mixed oxides of silica with alumina, ferric oxide, and titania have been measured by adsorption of ethylene glycol, water, and nitrogen. Surface areas from ethylene glycol adsorption give improbably high values. Isotherms of water adsorption indicate microporosity and estimates of the external surface area from water adsorption are similar to areas from nitrogen adsorption. An estimate of surface areas from potentiometric titration curves is made and compared to the areas from the other measurements. The area determined by titration falls between the areas from water and nitrogen adsorption. It is concluded that the most meaningful estimation of surface areas of hydrous amorphous oxides is obtained by considering an external surface area measured by nitrogen adsorption and an internal pore volume obtained from analysis of the water adsorption isotherm.
Published Version
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