Application: The UOP SelectFining process is a gasoline desulfurization technology developed to produce ultra-low-sulfur gasoline by removing more than 99% of the sulfur present in olefinic naphtha while:
• Minimizing octane loss
• Maximizing liquid yield
• Minimizing H2 consumption
• Eliminating recombination sulfur.
Description: The SelectFining process can hydrotreat full boiling-range (FBR) olefinic naphtha or, when used in conjunction with a naphtha splitter, any fraction of FBR naphtha.
The configuration of a single-stage SelectFining unit processing FBR olefinic naphtha (Fig. 1) is very similar to that of a conventional hydrotreater. The operating conditions of the SelectFining process are similar to those of conventional hydrotreating: it enables refiners to reuse existing idle hydroprocessing equipment.
Since FBR olefinic naphtha can contain highly reactive di-olefins (which may polymerize and foul equipment and catalyst beds), the SelectFining unit may include a separate reactor for di-olefin stabilization. Incoming naphtha is mixed with a small stream of heated hydrogen-rich recycle gas and directed to this reactor. The “stabilized” naphtha is then heated to final reaction conditions and processed in the unit’s main reactor over SelectFining catalyst.
Effluent from the main reactor is washed, cooled and separated into liquid and gaseous fractions. Recovered gases are scrubbed (for H2S removal) and recycled to the unit’s reactor section, while recovered liquids are debutanized (for Rvp control) and sent to gasoline blending.
Process chemistry: While the principal reactions that occur in a hydrotreater involve conversion of sulfur and nitrogen components, conventional hydrotreaters also promote other reactions, including olefin saturation, reducing the feed’s octane. UOP’s S 200 SelectFining catalyst was developed to effectively hydrotreat the olefinic naphtha while minimizing olefin saturation. It uses an amorphous alumina support (with optimized acidity) and non-noble metal promoters to achieve the optimal combination of desulfurization, olefin retention and operating stability.
In addition to processing FBR naphtha, the SelectFining technology can also be used in an integrated gasoline upgrading configuration that includes naphtha splitting, Merox extraction technology for mercaptan removal and ISAL hydroconversion technology for octane recovery.
Economics: A SelectFining unit can preserve olefins while desulfurizing FBR naphtha from a fluid catalytic cracking unit. When producing a 50-wppm sulfur product (~98% HDS), the additional olefin retention provided by the single-stage SelectFining unit corresponds to a 2.5 (R+M)/2 octane advantage relative to conventional hydrotreating. This advantage increases to 3.5 (R+M)/2 when a two-stage unit is used. Based upon an octane value of $0.50 per octane-bbl, hydrogen cost of $6 per 1,000 SCFB and 20,000 BPSD naphtha throughput, the resulting savings in processing costs can range from $8 to $12 million per year depending upon the SelectFining process flowscheme applied.
Licensor: UOP in cooperation with PDVSA-INTEVEP.