Application: The UOP Par-Isom process is an innovative application using high-performance nonchlorided-alumina catalysts for light-naphtha isomerization. The process uses PI-242 catalyst, which approaches the activity of chlorided alumina catalysts without requiring organic chloride injection. The catalyst is regenerable and is sulfur and water tolerant.
Description: The fresh C5 / C6 feed is combined with make-up and recycle hydrogen which is directed to a heat exchanger, where the reactants are heated to reaction temperature. The heated combined feed is then sent to the reactor. Either one or two reactors can be used in series, depending on the specific application.
The reactor effluent is cooled and sent to a product separator where the recycle hydrogen is separated from the other products. Recovered recycle hydrogen is directed to the recycle compressor and back to the reaction section. Liquid product is sent to a stabilizer column where light ends and any dissolved hydrogen are removed. The stabilized isomerate product can be sent directly to gasoline blending.
Feed: Typical feed sources for the Par-Isom process include hydrotreated light straight-run naphtha, light natural gasoline or condensate and light raffinate from benzene extraction units.
Water and oxygenates at concentrations of typical hydrotreated naphtha are not detrimental, although free water in the feedstock must be avoided. Sulfur suppresses activity, as expected, for any noble-metal based catalyst. However, the suppression effect is fully reversible by subsequent processing with clean feedstocks.
Yield: Typical product C5+ yields are 97 wt% of the fresh feed. The product octane is 81 to 87, depending on the flow configuration and feedstock qualities.