STABILIZATION AND SINTERING OF POROUS PT-SIO2 - A NEW APPROACH

Pt/SiO2 catalysts with well defined pore size distributions and metal particle sizes were prepared by the sol-gel method. Tetraethoxysilane (TEOS) and Pt(AcAc)2 were used as precursors. Pore size distributions were controlled by varying the H2O/TEOS ratio during synthesis. It, was found that when the particle size was matched to coincide with the average pore diameter the resulting Pt/SiO2 catalysts were resistant to sintering in O2 at temperatures up to 675-degrees-C. In order to insure that sintering did not occur it was found necessary to reduce the metal loading to between 0.2 to 0.3 wt.-%. In addition to a high resistance to sintering these catalysts were observed to be structurally stable. BET surface areas in excess of 800 m2/g were obtained and were, found to decrease only slightly following thermal treatment in O2 at 675-degrees-C. Additionally, pore structure and pore volume were observed to decrease only slightly following thermal treatment in oxygen.