Environmental concerns and regulations have driven the worldwide refineries to look for efficient and economic ways to reduce sulfur in gasoline. Regulators around the world are approaching stringent regulations of zero-sulfur gasoline (&lt;10 ppm). FCC gasoline, which accounts for 30-40% of the total gasoline pool and contributes about 90% of gasoline sulfur, is the main focus for gasoline sulfur reduction. One approach is to do in-situ reduction of gasoline sulfur during FCC process by using gasoline sulfur additive. Current commercial sulfur additives are mainly Zn-based and V-based catalysts. Some studies have been done to understand the reaction mechanisms of sulfur compounds during FCC process. However, study on sulfur reduction pathways by additives is limited in the literature. To better understand how gasoline sulfur additive works during FCC process, the sulfur chemistry study by Advanced Catalytic Evaluation (ACE) unit was conducted using clean base oil spiked with different sulfur compounds. The S removal efficiency depends not only on the type of S species but also on the catalyst. V-based additive is effective in removing benzothiophene via both in-situ hydrodesulfurization and S-coking. Zn-based additive is most effective in removing heavy sulfur species by S-coking. The development of BASF low sulfur additive utilized spectroscopic techniques such as Raman and UV-vis spectroscopies. These techniques helped to identify and characterize the V-based active species for sulfur reduction. It provides interesting understanding of highly active additive. The understanding of V chemistry in solution allows us to develop a novel method for simultaneous loading of both metal and vanadium on the support. The formation of metal vanadate on the exterior of the zeolite structure not only provides gasoline sulfur reduction function, but also greatly reduces the detrimental effect of vanadium on zeolite structure.

Understanding FCC gasoline sulfur reduction by low sulfur additives

252nd National Meeting (2016)

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