By: Steven HarrisCMEN 413-001

Overview“Virtually all of the world’s butyl rubber production is made by a precipitation polymerization process…(1)”

Feed stocks – Isobutylene (98%) and Isoprene (2%)Solvent – Methyl Chloride (approx. 65 wt%)Catalyst – Aluminum Chloride

Reaction takes place at 178K and 2-4 atm.

3 Main Divisions-Feed stocks purification/introduction- Polymerization reaction and purification - Solvent and Isobutylene recovery

Feed Stock IntroductionFirst stage – distillation drying of isobutylene (ESA)

Second stage – distillation purification of isobutylene removes higher boiling compounds (ESA)

Next – Isobutylene, Isoprene, and a recycled stream of Methyl Chloride and unreacted Isobutylene mix in the feed blend drum

Polymerization Reaction and PurificationFeed Mixture is chilled and pumped into reactor

Methyl Chloride passes over Aluminum Chloride bed in the catalyst dissolver to make the catalyst solution

Feed steams combine in the reactor, cyclic operation, 30 – 60 min per batch

Continuously overflow product slurry is sent to flash drum, steam is injected to remove Methyl Chloride (ESA)

Stripping Drum, vacuum (ESA)

Recycle and RecoveryRecycled gas stream is compressed and dried

Methyl Chloride removed from first distillation tower (ESA)

High purity Isobutylene is the top product in the second distillation tower (ESA)

Third tower separates lower grade Isobutylene as the top product from purge stream (fuel source) (ESA)