Effect of Sulfur on the Performance and on the Particle Size and Location of Platinum in Pt/KL Hexane Aromatization Catalysts

Sulfur, introduced to a working Pt/KL. hexane aromatization catalyst in the form of thiophene, functions as an extremely potent poison by reducing the number of Pt sites accessible within the channels of the KL zeolite. The intrinsic catalytic activity and selectivity of in-channel Pt sites, however, is not significantly modified by the presence of sulfur on the catalyst. Extremely low thiophene feed sulfur concentrations in the 50-200 wppb range accelerate Pt agglomeration. Catalyst deactivation, resulting primarily from metals agglomeration, most likely occurs by multiple blockage of KL channels by small (10-20 Å) Pt and/or Pt-sulfur clusters.Copyright 1993, 1999 Academic Press