Influence of O 2 and O 3 regeneration on the metallic phase of the Pt—Re/Al 2O 3 catalyst

Abstract

The influence of the regeneration with oxygen or ozone on the metallic function activity of the Pt—Re/Al 2O 3 catalyst prepared by catalytic reduction is studied. The interaction between Pt and Re is higher when activation is carried out by direct reduction. However, calcination at 450°C leads to a segregation of metals. The regeneration carried out with diluted O 2 destroys the metallic interaction producing segregation of Pt and Re, while the regeneration with O 3 at low temperature avoids such segregation to a large extent. Ozone not only burns coke off, but also modifies its burning characteristics as measured by temperature programmed oxidation technique (TPO) with 6% O 2/N 2. It was found that after the O 3 treatment, the coke left on the catalyst burns at lower temperatures if compared to the coke without O 3 treatment. Therefore, a regeneration treatment can be carried out at low temperatures by combining a first step with O 3 followed by a second one with O 2 at lower temperatures than those needed in conventional regeneration procedures.