| 主权项 |
1. An improved process for manufacturing polytetramethylene ether glycol comprising steps of (1) polymerizing tetrahydrofuran in the presence of an acylium ion precursor at polymerization effective conditions in a polymerization reaction zone to produce a first product mixture comprising tetrahydrofuran, acylium ion precursor, acid associated with the acylium ion precursor and diacetate of polytetramethylene ether glycol; (2) feeding the first product mixture of step (1) to a first stripping zone along with additional tetrahydrofuran to produce products comprising the diacetate and tetrahydrofuran; (3) determining the number average molecular weight of the diacetate product of step (2) by the formula: Mn=((A+B)×C)/M, wherein A is the net flow rate of acylium ion precursor to step (1), B is the sum of flow rates of tetrahydrofuran to step (1) and step (2), C is the number ratio of (2× methyl acetate molecular weight) divided by the azeotropic concentration of the methyl acetate component in M by weight; and M is the flow rate of methyl acetate azeotrope product of step (5); (4) feeding the diacetate product of step (2) to a methanolysis zone along with methanol and methanolysis catalyst to produce a second product mixture comprising methyl acetate, methanol, catalyst and polytetramethylene ether glycol; (5) feeding the second product mixture of step (4) to a second stripping zone to produce products comprising methyl acetate azeotrope and polytetramethylene ether glycol; and (6) recovering the polytetramethylene ether glycol; wherein A is adjusted to control the number average molecular weight of the diacetate product of step (2) to be from about 300 to about 2300 dalton. |
