The BASF process called SELOP is licensed by CB&I for C4 and C5 selective hydrogenation. In the process, C4s or C5s from an ethylene plant or MTO unit are selectively hydrogenated to convert the contained acetylenes and dienes to primarily olefins. The conversion of the acetylene and dienes is quite high, with specifications of 50 ppm or less being readily achieved on the outlet of the Selective Hydrogenation Unit (SHU). The number of reactor stages are typically two, but can vary from one to three stages depending on the diolefin content of the feed and the required production specification. The product from the SHU can be used as Olefins Conversion feed or Comonomer Production feed. The comonomer butene-1 can also be recovered directly from the SHU effluent after the isobutenes and isobutanes are removed or fractionated. The SELOP technology is widely used worldwide, with over 50 units in operation or under design.
The SELOP technology offers high selectivity to normal butenes and normal pentenes with minimum normal butane and normal pentane formation. No skeletal isomerization occurs, so no isobutene or isopentene are formed. Depending on the desired product, a low or high linear isomerization catalyst can be used, permitting the desired product to be maximized. This selectivity maximizes the value of the product stream and capacity of the downstream users thereby producing the best return on investment. There is no oligomer or polymer formation, which leads to very long run times between regenerations. This eliminates the need for a spare reactor on all but the first stage reactor, thereby minimizing investment. Superior hydrogen distribution by proprietary reactor internals minimizes reactor size and catalyst volume, further minimizing investment. The high selectivity for mixed C5 hydrogenation is unique to the SELOP process making it the system of choice for selective C5 hydrogenation. The superior catalyst offers long life and long cycle times while maintaining high selectivity.