THIOL FORMATION AND CONVERSION IN FCC NAPHTHA DESULFURIZATION

摘要

The objective of FCC naphtha selective hydrodesulfurization (SHDS)technologies,such as the SelectFiningTM process licensed by UOP,is to reduce the sulfur content of the naphtha while simultaneously maintaining its octane value by minimizing olefin saturation.Both of these objectives are complicated by recombination,the term applied to the reaction of H2S and olefins to form thiols.A solid understanding of recombination reaction kinetics is critical in the design and operation of selective hydrodesulfurization units as the lowest achievable sulfur level in a single stage may be dictated by the extent of recombination.Furthermore,recombination contributes to the conversion of the valuable high octane olefins.Thiols formed by recombination are converted through a hydrodesulfurization mechanism.This socalled drainage reaction creates a second route for olefin conversion.