Abstract:
Counter claims appear in the literature on the effects of the particle size, sintering and pre-treat- ment of a catalyst on its activity. We have investigated these by studying a platinum black catalyst and the way in which helium, hydrogen, air, oxygen and thermal cycling affect the particle size as seen in the electron microscope. By making a logical sequence of experiments it has been possible to show that the sintering of the catalyst was most affected by the presence of hydrogen which caused considerable growth in crystallite size. It thus seems possible that apparent effects of reaction and thermal treatment may have, in previous work, been caused by pre-treatment in hydrogen.
