Polyisobutylene production process with improved efficiencies and/or for forming products having improved characteristics and polyisobutylene products produced thereby
View Patent ↗A process for production of polyisobutylene includes subjecting a reaction admixture comprising isobutylene, a diluent for the isobutylene, which may be isobutane, and a catalyst composition, that may include a BF 3 /methanol catalyst complex, to reaction conditions suitable for causing at least a portion of the isobutylene to undergo polymerization to form a polyisobutylene product including polyisobutylene molecules. At least a fraction of the polyisobutylene molecules thus produced have alpha position double bonds and the polyisobutylene product has a number average molecular weight (M N ) and a polydispersity index (PDI). The concentration of the diluent in the reaction admixture may be manipulated to control or change any one or more of (a) the relative size of the fraction, (b) the number average molecular weight of the product, (c) the polydispersity index of the product and (d) the relative size of the portion. The diluent concentration may be held constant to maintain any one or more of such characteristics constant.
1. A process for production of polyisobutylene comprising:
subjecting a reaction admixture comprising isobutylene, a diluent for said isobutylene and a catalyst composition to reaction conditions in a reaction zone suitable for causing at least a portion of said isobutylene to undergo polymerization to form a polyisobutylene product including polyisobutylene molecules, at least a fraction of said polyisobutylene molecules having alpha position double bonds, said polyisobutylene product having a number average molecular weight and a polydispersity index;
choosing a diluent concentration corresponding to a pre-selected value of at least one parameter selected from the size of the fraction or the molecular weight;
maintaining the admixture at said chosen diluent concentration to thereby hold said parameter at said pre-selected value;
treating said product to remove diluent and unreacted isobutylene therefrom; and
recycling at least one of the diluent and the unreacted isobutylene back to said zone, wherein said diluent consists essentially of isobutane and a C 3 -C 16 1-alkene.
2. The process as set forth in claim 1 , wherein the diluent comprises a mixture of isobutane and 1-butene.
3. A process for production of polyisobutylene comprising:
subjecting a reaction admixture comprising isobutylene, a diluent for said isobutylene and a catalyst composition to reaction conditions suitable for causing at least a portion of said isobutylene to undergo polymerization to form a polyisobutylene product including polyisobutylene molecules, at least a fraction of said polyisobutylene molecules having alpha position double bonds, said polyisobutylene product having a number average molecular weight and a polydispersity index, said polyisobutylene product having at least one parameter that is variable as a function of the concentration of said diluent in said admixture, said at least one parameter comprising (a) the relative size of said fraction, (b) the number average molecular weight of said product, (c) the polydispersity index of said product or (d) the relative size of said portion;
choosing a diluent concentration corresponding to a pre-selected value of at least one parameter; and
maintaining the admixture at said chosen diluent concentration to thereby hold said parameter at said pre-selected value,
wherein diluent comprising a C 3 -C 16 1-alkene and optionally a C 3 -C 16 alkane is provided to a reactor independently of fresh isobutylene monomer.
4. The process according to claim 3 , wherein the independently provided diluent consists essentially of isobutane and a C 3 -C 16 1-alkene.