Process for suppression of hydrogenolysis and c.sub.5.sup.+ liquid yield

Abstract

In a reforming process wherein a feed naphtha is reformed, with hydrogen, over a reforming catalyst in a process unit, the improvement comprising the addition of infinitesimal, or small amounts of water or hydrogen halide, or both, or substance which can produce in situ water or hydrogen halide, or both, during the reforming operation to displace previously adsorbed sulfur, or to suppress the adsorption of sulfur by the catalyst to control the amount of sulfur added to the catalyst to a minimum effective level. It has been found, in the sequence of regeneration and reactivation, that the ability of a catalyst to operate in a hydrogenolysis mode can be effectively suppressed after the freshly prepared catalyst has been regenerated, and reactivated several times, generally above five times or more, by presulfiding the catalyst by the addition of a minimal amount of sulfur, preferably a maximum of about 0.01 weight percent sulfur on the catalyst. Water is injected to displace excess sulfur from oversulfided catalyst and a water wave will travel downstream from the catalyst of a reactor to either redistribute sulfur to any undersulfided catalysts of other reactors or help purge the excess sulfur from the system in the form of hydrogen sulfide released to and carried by the recycle gas. Preferably, a modified catalyst presulfiding regimen is imposed wherein the amount of sulfur added to a fresh catalyst is progressively, and preferably proportionately reduced from one regeneration, reactivation sequence to the next such that, on and after about the fifth regeneration, and reactivation of the catalyst a maximum of about 0.01 weight percent sulfur is added to the catalyst.