The present invention relates to high performance, crosslinked hollow-fibre membranes and a new process for manufacturing the same.

A pass or tube or a section thereof or U bend in a coil in a paraffin cracker having section having a pore size in the metal substrate from about 0.001 to 0.5 microns over coated with a dense metal membrane permits the permeation of one or more of H.sub.2, CH.sub.4, CO and CO.sub.2 from cracked gases moving the reaction equilibrium to the production of ethylene and reduces the load on the down-stream separation train of the steam cracker.

A co-cast thin film composite flat sheet membrane is provided that comprises an asymmetric porous non-selective support layer with a thickness of 10-50 micrometers and an asymmetric integrally skinned polyimide-containing selective layer with a thickness of 5-40 micrometers on top of said support layer, wherein said asymmetric integrally skinned polyimide-containing selective layer comprises a porous non-selective polyimide-containing support layer with a thickness of 5-40 micrometers and a relatively porous, thin, dense, polyimide-containing top skin layer with a thickness of 0.02-0.2 micrometers.

The present invention relates to a polymeric hollow fiber membrane and a carbon molecular sieve hollow fiber membrane, both of which have excellent gas separation performance, and processes for preparing the same. Specifically, the present invention relates to a hybrid polymeric hollow fiber membrane that comprises a glassy polymer containing fluorine and a ladder-structured polysilsesquioxane, a hybrid carbon molecular sieve hollow fiber membrane prepared by pyrolysis thereof, and processes for preparing the same. The hybrid polymeric hollow fiber membrane and the hybrid carbon molecular sieve hollow fiber membrane according to the embodiments of the present invention are excellent in gas flux and selectivity and can have a large surface area per unit volume. Thus, they can be advantageously used for separating gases with a high energy efficiency on a large scale.

A method for forming an isoporous graded film comprising multiblock copolymers and isoporous graded films. The films have a surface layer and a bulk layer. The surface layer can have at least 1?10.sup.14 pores/m.sup.2 and a pore size distribution (d.sub.max/d.sub.min)) of less than 3. The bulk layer has an asymmetric structure. The films can be used in filtration applications.

Provided are a hydrophilic porous membrane including a porous membrane and a hydroxyalkyl cellulose retained in the porous membrane, in which the average pore size differs between two surfaces of the porous membrane, the hydroxyalkyl cellulose distributed in the thickness direction of the hydrophilic porous membrane exhibits two or more peaks of detection intensity in GPC, and the weight-average molecular weight Mw.sub.min of the peak that is detected latest among the above-mentioned peaks is less than 100,000; and a method for producing a hydrophilic porous membrane, the method including separately preparing a hydrophilizing liquid including a hydroxyalkyl cellulose having a smaller weight-average molecular weight and a hydrophilizing liquid including a hydroxyalkyl cellulose having a larger weight-average molecular weight, and applying each of the hydrophilizing liquids on two surfaces of the porous membrane or sequentially on one surface thereof.

A stable high performance facilitated transport membrane comprising an asymmetric integrally-skinned polymeric membrane wherein the pores on the relatively porous, thin, dense skin layer of the membrane comprises a hydrophilic polymer such as chitosan or sodium alginate, a metal salt such as silver nitrate, or a mixture of a metal salt such as silver nitrate and hydrogen peroxide and the asymmetric integrally-skinned polymeric membrane comprises a relatively porous, thin, dense skin layer as characterized by a CO.sub.2 permeance of at least 200 GPU and a CO.sub.2 over CH.sub.4 selectivity between 1.1 and 10 at 50? C. under 50-1000 psig, 10% CO.sub.2/90% CH.sub.4 mixed gas feed pressure. The present invention further includes a method of making these membranes and their use for olefin/paraffin separations, particularly for propylene/propane and ethylene/ethane separations.

Hydrophobic poly(4-methyl-1-pentene) hollow fiber membrane for retention of anesthetic agents with an inner and an outer surface and between inner and outer surface an essentially isotropic support layer with a sponge-like, open-pored, microporous structure free of macrovoids and adjacent to this support layer on the outer surface a dense separation layer with a thickness between 1.0 and 3.5 ?m. The membrane has a porosity in the range of greater than 35% to less than 50% by volume and a permeance for CO.sub.2 of IN 20-60 mol/(h.Math.m.sup.2.Math.bar), a gas separation factor ?(CO.sub.2/N.sub.2) of at least 5 and a selectivity CO.sub.2/anesthetic agents of at least 150. The process of for producing this membrane is based on a thermally induced phase separation process in which process a homogeneous solution of a poly(4-methyl-1-pentene) in a solvent system containing components A and B is formed, wherein component A is a strong solvent and component B a weak non-solvent for the polymer component. After formation of a hollow fiber the hollow fiber is cooled in a liquid cooling medium to form a hollow fiber membrane. The concentration of the polymer component in the solution may be in the range from 42.5 to 45.8 wt.-% and the hollow fiber leaving the die runs through a gap between die and cooling medium with a gap length in the range of 5-30 mm.

Novel carbon molecular sieve (CMS) compositions comprising carbonized vinylidene chloride copolymer having micropores with an average micropore size ranging from 3.0 to 5.0. These materials offer capability in separations of gas mixtures including, for example, propane/propylene; nitrogen/methane; and ethane/ethylene. Such may be prepared by a process wherein vinylidene chloride copolymer beads, melt extruded film or fiber are pretreated to form a precursor that is finally carbonized at high temperature. Preselection or knowledge of precursor crystallinity and attained maximum pyrolysis temperature enables preselection or knowledge of a average micropore size, according to the equation ?=6.09+(0.0275?C)?(0.00233?T), wherein ? is the average micropore size in Angstroms, C is the crystallinity percentage and T is the attained maximum pyrolysis temperature in degrees Celsius, provided that crystallinity percentage ranges from 25 to 75 and temperature in degrees Celsius ranges from 800 to 1700. The beads, fibers or film may be ground, post-pyrolysis, and combined with a non-coating binder to form extruded pellets, or alternatively the fibers may be woven, either before or after pre-treatment, to form a woven fiber sheet which is thereafter pyrolyzed to form a woven fiber adsorbent.

When the porous membrane, which has two surfaces of a surface A and a surface C, is equally divided in the thickness direction of the porous membrane into three layers of a first layer including the surface A, a second layer that is a central layer in the thickness direction, and a third layer including the surface C, an average trunk size of the third layer is larger than an average trunk size of the second layer, and when a continuous layer from the surface A having a thickness of 10 ?m in the first layer is a first layer component, a continuous layer component having a thickness of 10 ?m and an average trunk size smaller than an average trunk size of the first layer component is present in the first layer, the second layer, and the third layer other than the first layer component.