Common methods to polymerize isobutylene and form polyisobutylene (PM) with one carbon-carbon double bond include using Lewis acid catalysts, such as boron trifluoride (BF3) and aluminum trichloride (AlCl3). The double bond can be located at the end of the polymer chain (e.g., alpha vinylidenes) or it can be located more internal in the chain as in beta vinylidene or other trisubstituted olefin isomers, or tetra substituted olefin isomers. PM containing a high proportion of alpha vinylidene olefin isomers is referred to as highly reactive polyisobutylene (HR-PIB). Such polymer molecules are more reactive in subsequent derivatization reactions to produce derivatives such as fuel and lubricant additives than other types of PIB.
Conventional AlCl3 catalysts typically produce PIB that has olefin isomers other than alpha vinylidene. These PIB products are known as conventional PIB and are significantly less reactive in derivatization reactions.
Catalyst complexes (such as liquid BF3/complexing agent) have been developed to produce HR-PIB. See U.S. Pat. Nos. 6,525,149; 6,562,913; 6,683,138; and 6,884,858. However, many liquid BF3/complexing agents are unstable and must be prepared in situ, requiring the handling of highly toxic BF3 gas on site. The liquid BF3/complexing agents must also be removed post-reaction by extensive water washing processes which are highly complex and generate large amounts of waste water. Moreover, the waste water contains fluoride salts that require disposal.
U.S. Pat. Nos. 8,791,216 and 8,816,028 describe polyisobutylene compositions, and methods and catalyst systems to produce such compositions. The catalyst system is a solid BF3/alcohol catalyst complex on a metal oxide support material of gamma alumina beads or spheres, and the catalyst system is used in a fixed bed reactor. The PIB products made include internal vinylidene isomers and alpha vinylidene isomers, such that the alpha vinylidene olefin isomers in these compositions are significantly less than 75 wt %.
U.S. Pat. No. 9,040,645 discloses a method of preparing alumina with pores and reacting BF3/methanol complexes with the porous alumina. The BF3/methanol/alumina catalyst system produces PM compositions in which the alpha vinylidene isomer content is significantly less than 75 wt %.
Other references that describe conventional PIB processes and catalysts include: U.S. Pat. Nos. 5,710,225; 5,945,575; 6,384,164; 6,441,110; 6,710,140; and 6,992,152.
There exists a need for an improved process to produce HR-PIB compositions having an alpha vinylidene olefin isomer content greater than about 75% and catalyst for producing such materials.
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