Reactivation of iridium-containing catalysts

Abstract

A process wherein a coked, deactivated iridium-containing catalyst can be reactivated in a sequence of burn steps, inclusive of a low temperature primary burn step and a subsequent high temperature burn step. In (1) the low temperature primary burn step (i) the chloride level of the catalyst is raised and the catalyst passivated by contact with a hydrogen chloride containing gas, (ii) and coke is then burned from the catalyst by contact with a gas which contains hydrogen chloride at level sufficient to suppress iridium agglomeration at a level of oxygen providing burn temperatures which do not exceed about 425.degree. C., this being sufficient to remove a preponderance of the coke without agglomeration of the iridium component. (2) In a high temperature secondary burn step the catalyst is subjected to (iii) a chlorination step wherein the catalyst is contacted with a hydrogen chloride containing gas sufficient to raise the chloride level of the catalyst to a yet higher level for suppression of iridium agglomeration at higher temperature than 425.degree. C., (iv) residual coke is then burned from said catalyst by contact with a gas which contains hydrogen chloride at level sufficient to suppress iridium agglomeration at a level of oxygen sufficient to provide temperatures greater than 425.degree. C., sufficient to burn residual coke from the catalyst without agglomeration of the iridium. The high chloride catalyst can then be (3) stripped with steam, or steam and hydrogen chloride to reduce the level of chloride.