ALLOYING IN PLATINUM-BASED CATALYSTS FOR GASOLINE REFORMING - A GENERAL STRUCTURAL PROPOSAL

Platinum/alumina catalysts have been used for many years in the process of gasoline octane upgrading normally referred to as reforming. It is now standard industrial practice to add another element to the catalyst, which may be chosen from many parts of the periodic table, and which acts to prolong the life and improve the selectivity of the catalyst. Additives in use include gallium, germanium, iridium, tin, rhenium and chromium. It is proposed that each of these components alloys with the platinum, but in such a way that the exposed surface of the catalyst particles continues to be wholly platinum. The alloying element is enriched in the immediate subsurface layer, and modifies the properties of the catalyst through an electronic interaction.