Moving bed regeneration process with separate dispersion and chloriding

Abstract

A process for reforming hydrocarbons has a regeneration process for reconditioning catalyst particles containing platinum that improves the process by transferring the catalyst particles through a combustion zone, a drying zone, a redispersion zone and a chloride uptake zone. Drying of the catalyst particles immediately after the combustion of coke improves the operation of a platinum redispersion zone and a chloride uptake zone. Separate platinum redispersion zones and chloride uptake zones are provided so that the dried catalyst that enters the platinum redispersion zone can be contacted with a high concentration of chlorine with a lower overall concentration of chloride compounds in the redispersion zone. The lower moisture content allows the equilibrium reaction between hydrogen chloride and oxygen on the one hand, and water and chlorine on the other hand to be shifted to the production of chlorine. This shift of the equilibrium reaction can be further improved by maintaining an oxygen-enriched environment within the platinum redispersion zone. Conversely, the chloride uptake zone would have essentially all the chloride contained therein in the form of hydrogen chloride. Only a relatively low concentration of hydrogen chloride is needed and the chloride uptake zone can be designed such that virtually all of the chloride compounds entering the zone are taken up with the catalyst. The uptake of virtually all the hydrogen chloride in the chloride uptake zone and the use of a much lower chloride concentration in the redispersion zone reduces the emissions of hydrogen chloride from the regeneration zone. Aside from improving the platinum redispersion, the overall reduction of chlorides in the platinum redispersion zone allows the elimination of a costly halogen circulation loop that was previously needed in a halogenation zone to maintain a sufficient chlorine concentration for redispersion of the platinum.