scope:

This method is for determining the dispersion of alumina supported platinum (Pt) on fresh or regenerated catalyst containing Pt alone or Pt plus tin. Catalyst, such as presulfided or spent, containing sulfides, carbon, or greater than 1.5 mass-% chlorides, cannot be reliably analyzed. This method is applicable to catalyst sizes ranging from 0.29 mm (50 mesh) to 3.99 mm (5 mesh).

The results are expressed as the ratio of the number of moles of hydrogen chemisorbed to the number of moles of Pt in the catalyst. A ratio of 1.00 is defined as 100% dispersion (all the Pt atoms are available for catalysis). Values less than 1.00 may indicate crystallite growth or a surface interference. Also, the resulting H2/Pt values can be affected by elements other than Pt on the catalyst. The Pt content of the test sample is determined by the appropriate UOP Method for the catalyst type.