Abstract: A multi-layer membrane structure including a crosslinked polymeric membrane, such as a crosslinked polyvinyl sulfate membrane or a crosslinked copolymer polyvinyl sulfate and polyvinyl alcohol membrane, is provided. The membrane structure is suitable for use in an acid environment, and is suitable for recovering acid from a feed mixture comprising acid, hydrocarbons and water.

Abstract: A process in which a catalytic cracking unit is operated to crack a hydrocarbon feedstock in a manner to enhance light olefin yields. The accompanying benzene-containing naphtha product stream is further processed through a benzene selective membrane to provide a low content benzene stream. Refiners frequently operate their cracking units to optimize light olefin yields, e.g. propylene, in response to needs in the petrochemical industry, and it has been discovered that units operated in this manner frequently produce naphtha containing increased amounts of benzene. The method of this invention therefore allows one to operate the unit when it is desired to optimize light olefin yields, yet at the same time produce a naphtha yield having a low benzene content. The invention is particularly useful when the cracking unit utilizes pentasil zeolites at increased concentrations to enhance light olefins yield.

Abstract: Permselective separation of aromatic hydrocarbons from non-aromatic hydrocarbons in a feed stream is accomplished using improved asymmetric membranes. The preferred membranes are fashioned from a polyimide and conditioned with a lubricating oil. Feed streams containing a mixture of aromatic and non-aromatic hydrocarbons are contacted with the dense active layer side of the polyimide membrane under a pressure and temperature sufficient to selectively permeate the desired aromatic hydrocarbon.

Abstract: A semicontinuous process for solvent dewaxing a waxy petroleum oil feed stream including the steps of: diluting of the waxy oil feed stream with solvent; feeding cold oil/solvent/wax mixture to a filter to remove the wax and obtain an oil/solvent filtrate stream; contacting the oil/solvent filtrate stream with a selective semipermeable membrane to selectively transfer solvent through the membrane to obtain a solvent-rich permeate; and periodically directing a warm stream of recovered solvent onto the membrane surface to wash the membrane and remove impurities therefrom.

Abstract: An improved asymmetric membrane fashioned from a polyimide for the liquid separation of solvents from lube oil. The membrane is based on a fully imidized polymer based on 5(6)-amino-1-(4'-aminophenyl)-1,3,3-trimethylindane polymer and benzophenone tetracarboxylic dianhydride.

Abstract: An improved asymmetric membrane fashioned from a polyimide for the liquid separation of solvents from lube oil. The membrane is based on a fully imidized polymer based on 5(6)-amino-1-(4'-aminophenyl)-1,3-trimethylindane polymer and benzophenone tetracarboxylic dianhydride.

Abstract: The instant invention is a membrane useful for separating organic matter such as proteins from aqueous solutions which resists fouling and maintains a high flux during separation. The membrane is prepared by either drying a polysulfone composite membrane, or first treating a polysulfone composite membrane with aqueous methanol and then drying it. The membrane is then exposed to elemental fluorine in an inert gas in the substantial absence of oxygen at a temperature in the range of about -45.degree. to 70.degree. C. After fluorine treatment, the membrane is exposed to air. The fluorine content in the treatment mixture may be from 0.0125 to about 10 volume percent, preferably 0.025 to 2 volume percent. The fluorine treatment does not significantly alter the membrane pore size.

Abstract: An absorbent article comprising a cellulosic membrane about 5 to 50 .mu.m thick prepared by casting a film from solution of a cellulose derivative in a suitable solution and these formed into a packet which encapsulates an osmotic promoter, particularly sodium chloride, sugar or other suitable compound, preferably having a molecular weight below about 500. The packet is capable of taking up at least 0.001 g/cm.sup.2 /min of water and retaining it against an external pressure of at least 0.689 kPa.