Characterization of the Thermal Surface, and Oxygen Adsorption Properties of Type 4A and 5A Synthetic Zeolites

摘要

Thermal and surface properties of a Davison 4A zeolite were investigated using DTA, TGA, and oxygen adsorption at -196 exp 0 C. Surface properties of a Linde 5A zeolite were also evaluated using oxygen adsorption and compared with similar properties determined by nitrogen adsorption. Temperature programmed desorption analyses were performed using the TGA data and showed the activation energy for water desorption to be 7.8 kcal/mol. Adsorbed water was found to inhibit oxygen adsorption, but this inhibiting influence was reduced by increasing the outgassing temperature and eliminated by outgassing at 200 exp 0 C or higher. Pore volumes and diameters were determined using the MP method. Total pore volume was 0.225 cm exp 3 /g for the 4A and 0.261 cm exp 3 /g for the 5A. These values agreed well with those calculated using other methods. Pore diameters determined from oxygen adsorption were about 6 A which was greater than previously reported and indicated that this method was not sensitive enough to determine pore sizes with an accuracy greater than 1 to 2 A. (ERA citation 10:008866)