| 摘要 |
A new membrane for the separation of aromatic hydrocarbons from mixtures of said aromatic hydrocarbons and non-aromatic hydrocarbons has been prepared comprising a highly aromatic polyurethane membrane. These highly aromatic polyurea/urethane membranes are symmetric, dense film membranes made from the corresponding polyurea/urethane copolymers by standard membrane casting techniques. The polyurea/urethane copolymers are produced by reacting dihydroxy or polyhydroxy compounds, such as polyethers or polyesters having molecular weights in the range of about 500 to 5000 with aliphatic, alkylaromatic or aromatic diisocyanates or polyisocyanates and low molecular weight chain extenders, such as diamines, polyamines or amino alcohols. The membrane made from the polyurea/urethane copolymer, useful for the separation of aromatics from mixtures thereof with non-aromatics, in, for example, a naphtha feed stream, is characterized by possessing a urea index of at least about 20% but less than 100%, an aromatic carbon content of at least about 15 mole percent, a functional group density of at least about 10 per 1000 grams of polymer and a C=O/NH ratio of less than about 8.0. As stated, these membranes are useful for separating aromatics, from non-aromatics in petroleum refining and chemical applications. |
