Polybutenes
| 원료 | Feed |
| 생산물 | polybutenes |
| 적용 | To produce liquid polybutene (polyisobutylene) from mixed C4 hydrocarbon streams containing isobutylene. Products range in molecular weight from 300 to 2,700 and in viscosity from 40 to 30,000 SSU at 210℉ |
| 설명 | Description:
The feed stream to the process consists of a mixture of C4 olefins and paraffins containing 15 to 60% isobutylene. The feedstock normally is a C4 stream from refinery catalytic crackers or a naphtha cracker. The feed must be low in unsaturated C3 and C5 sulfur containing compounds and water. Facilities for removal of these compounds are provided in the feed treatment section. Following the feed treatment of caustic wash (1), water wash (2) and distillation drying (3), the treated feed from the surge drum (4) is pumped to the reactor (5) where liquid-phase polymerization occurs. Aluninum chloride catalyst is added continuously as a polymer slurry. The heat of reaction is removed by mechanical refrigeration. During the reaction, isobutylene is preferentially converted to polymer, and lesser amounts of normal butenes are polymerized. The reactor temperature and catalyst concentration are the primary means of controlling product properties. The catalyst in the product leaving the settler (6) is neutralized by a caustic wash (7) followed by a water wash (8). The mixture emerging from the final wash consists of C4 hydrocarbons, polybutene product and light polymers. Separation is achieved in three steps. First, the butanes and unreacted butenes are removed by distillation (9) under pressure. The overhead C4 stream is essentially free of polymer and is suitable for further processing such as alkylation or LPG production. When a feed containing a high concentration of isobutylene is used, part of the debutanizer overheated is recycled to the reactor. Next, the debutanizer bottoms stream is flashed (10) at atmospoheric pressure for the removal of low-boiling light polymers and traces of butane. Finally, the remaining light polymer is separated in a vacuum stripper (11) in order to meet flash and viscosity specifications on the finished product. Following filtration, the vacuum stripper bottoms is sent to storage to await shipment in drums, tank trucks or tank cars. |
