Process for selective sulfur removal from FCC naphthas using zeolite catalysts

摘要

A process for the removal of sulfur compounds from FCC catalytic naphtha which is simple to implement and is economical in operation operates by selectively hydrofining the cracked naphtha to remove sulfur without sacrificing octane (hydrodesulfurization typically around 85%) followed by a downstream alkylation which will remove residual sulfur from the gasoline boiling range. The alkylation is carried out using a solid, acidic molecular sieve catalyst under mild conditions to shift sulfur species from the lighter, olefin-rich portions of the naphtha to the heavy, olefin-poor gasoline. Separation of the heavy portion of the treated product followed by catalytic hydrodesulfurization or some other means (e.g. sorption) removes the sulfur from the heavy portion without losing significant octane value. Some of the heavy compounds formed in this process can drop out of the gasoline range, into the kero/light diesel range; this stream can be hydrotreated without penalty since octane is not a requirement for the middle distillate fuels.