INDUSTRIAL REGENERATION OF NAPHTHA REFORMING CATALYSTS CONTAMINATED BY SULFATE-IONS - EFFECT OF SULFATE LEVEL

When naphtha reforming catalysts are sulfur contaminated, a special procedure is employed during catalyst regeneration to diminish the sulfation of the support. Thus, from an industrial point of view it is important to know the effect of the sulfate level on the naphtha reforming process. In this paper, most of the results were obtained on a Pt-Re/Al2O3 catalyst taken from commercial reforming reactors. Fresh Pt-Re/Al2O3 catalyst was also employed. The effect of the sulfate level on naphtha reforming was studied through an accelerated deactivation run at reforming conditions using a naphtha feed. Correlations were established through the analysis of parameters such as octane number, volumetric liquid yield, percentage of gases, percentage of aromatics in the liquid, and coke formation. The results showed that for sulfate levels higher than 0.08-0.1% S the rate of deactivation is increased as a consequence of enhanced coke formation. Such an increase of the coke formation results from (a) the difficulty of restoring the chlorine level on the support because of the blockage of the Lewis acid sites of the alumina by sulfate ions and (b) excessive sulfidation of the metallic fraction by H2S produced during the reduction of the sulfated catalysts with H-2.