PEP Review 94-3-2
Polytetramethylene Glycol from Tetrahydrofuran via a Diacetate Intermediate
Published: May 1996
In January 1994, DuPont announced a new process to produce polytetramethylene glycol (PTMEG) from tetrahydrofuran (THF). We believe the process starts with reaction of THF and acetic anhydride to form PTMEG diacetate as an intermediate. This review presents SRI's interpretation of the process based on recent DuPont patents. Note, however, that DuPont has informed SRI that much of the technology to be used in its new process has not yet been disclosed.
SRI's design includes three basic steps:
- Batch polymerization of THF and acetic anhydride over a solid zirconium oxide catalyst to form the diacetate intermediate
- Batch reaction of the diacetate with methanol to form crude PTMEG and the methanol/methyl-acetate azeotrope as a by-product
- Removal of a low-molecular-weight fraction (oligomer) from the crude PTMEG to form a finished product
Capital requirements for the new process were estimated to be lower than those for the old process. The results are reasonably close to DuPont's claims of savings in both capital and operating costs for its new PTMEG process.