Application: The Dimer8 process uses a fixed-bed reactor followed by catalytic distillation to achieve final isobutene conversion at high dimer selectivity. The Dimer8 process is the most attractive technology for converting a refinery-based methyl tertiary butyl ether (MTBE) unit to isooctene/isooctane production.
Description: The selective dimerization of isobutenes over acidic ionexchange resin produces isooctene or di-isobutylene (DIB). Oxygenates such as methanol, MTBE, water or tert-butyl-alcohol (TBA) are used as selectivators for the dimerization reaction, to prevent formation of heavier oligomers. The Dimer8 process uses a fixed-bed reactor followed by catalytic distillation to achieve final isobutene conversion at high dimer selectivity.
The primary fixed-bed reactor can utilize a boiling point reactor or a water-cooled tubular reactor (WCTR) design depending on the finished product and operational requirements of the refiner. Either reactor can be used to achieve high isobutylene conversion with excellent dimmer selectivity.
The unique catalytic distillation (CD) column combines reaction and distillation in a single unit operation. Continuous removal of heavier dimer product from the reaction zone enables further conversion of isobutene without loss of dimer selectivity. The use of CD eliminates the need for any downstream reaction/fractionation system to achieve such performance.
Isooctene can be used as a gasoline blendstock due to its excellent characteristics. Should olefin restrictions require a paraffinic product, the isooctene product can be saturated to isooctane in a trickle-bed hydrogenation reactor. Hydrogenation uses a base or noble metal catalyst depending on the feed contamination level.
Process advantages include:
• Easy implementation, minimum revamp changes, low capital cost,
short schedule
• 90+% isobutylene conversion
• 80+% C8 selectivity
• High flexibility
• Simple control
• High octane/low Rvp blend stock
• Low utilities.
Licensor: Jointly licensed CDTECH and Snamprogetti.
