POLYBENZOXAZOLE MEMBRANES FROM SELF-CROSS-LINKABLE AROMATIC POLYIMIDE MEMBRANES

摘要

A method of making a polybenzoxazole (PBO) membrane from a self-cross-linked aromatic polyimide polymer membrane is provided. These membranes are useful in the separation of gas mixtures and liquid mixtures. The PBO membrane is made by fabricating a self-cross-linkable aromatic polyimide polymer membrane comprising both hydroxyl functional groups and carboxylic acid functional groups; cross-linking the polymer to form a self-cross-linked aromatic polyimide polymer membrane by heating the membrane at 250° to 300° C. under an inert atmosphere; and thermal heating the self-cross-linked aromatic polyimide polymer membrane at a temperature from about 350° to 500° C. under an inert atmosphere to convert the self-cross-linked aromatic polyimide polymer membrane into a PBO membrane. A membrane coating step may be added by coating the selective layer surface of the PBO membrane with a thin layer of high permeability material.

主权项

1. A process for separating at least one gas from a mixture of gases comprising providing a polybenzoxazole membrane of formula (III) comprising wherein said formula (III) is: wherein X1 is selected from the group consisting of and mixtures thereof; wherein X3 is selected from the group consisting of and mixtures thereof; wherein X4 is selected from the group consisting of and mixtures thereof; Y1 is selected from the group consisting of and mixtures thereof; Y2 is selected from the group consisting of and mixtures thereof, and —R′— is selected from the group consisting of and mixtures thereof; o and q are independent integers from 2 to 500 contacting the mixture of gases to one side of the polybenzoxazole membrane of formula (III) to cause at least one gas to permeate said membrane; and removing from an opposite side of said polybenzoxazole membrane of formula (III) a permeate gas composition comprising a portion of said at least one gas that permeated said membrane.