The present invention relates to a process for the production of asymmetric cellulose hollow fibres and the use of such fibres in the production of asymmetric carbon hollow fibre membranes (CHFMs). In particular, the present invention provides a facile and scalable process for the preparation of asymmetric CHFMs by direct pyrolysis of polymeric precursors without the need for complex pre-pyrolysis treatment steps to prevent pore collapse. The present invention also relates to the use of asymmetric CHFMs prepared according to said process in the separation of hydrogen gas from a mixed gas source, especially in the separation of hydrogen from CO.sub.2 in the steam-methane reforming reaction.

Disclosed are super-hydrophobic, super oleophilic membranes comprising a metal mesh comprising copper, a coating comprising a carbohydrate derivative, wherein the carbohydrate derivative is covalently or ionically bonded to a metal mesh surface and methods of preparation thereof. The disclosed membranes are useful for wastewater treatment in the oil industry, in particular for oil/water separation processes.

Provided herein are methods for making a freeze-cast material having a internal structure, the methods comprising steps of: determining the internal structure of the material, the internal structure having a plurality of pores, wherein: each of the plurality of pores has directionality; and the step of determining comprises: selecting a temperature gradient and a freezing front velocity to obtain the determined internal structure based on the selected temperature gradient and the selected freezing front velocity; directionally freezing a liquid formulation to form a frozen solid, the step of directionally freezing comprising: controlling the temperature gradient and the freezing front velocity to match the selected temperature gradient and the selected freezing front velocity during directionally freezing; wherein the liquid formulation comprises at least one solvent and at least one dispersed species; and subliming the at least one solvent out of the frozen solid to form the material.

The present disclosure relates to a mixed matrix carbon molecular sieve (CMS) membrane, a preparation method of the mixed matrix CMS membrane, and use of the mixed matrix CMS membrane in C.sub.2H.sub.4/C.sub.2H.sub.6 separation, and belongs to the technical field of membrane separation. The present disclosure solves the problem that the CMS materials in the prior art exhibit low selectivity and low flux during an ethylene/ethane separation process. In this patent, C.sub.3N.sub.4 is used as a filling particle to prepare a mixed matrix membrane (MMM), and the MMM is pyrolyzed to prepare a CMS membrane. The C.sub.3N.sub.4/6FDA-DAM MMM has prominent C.sub.2 separation performance.

An asymmetric polyvinylidene chloride copolymer membrane is made by a method using a dope solution comprised of a polyvinylidene chloride copolymer and a solvent that solubilizes the polyvinylidene chloride copolymer that is shaped to form an initial shaped membrane. The initial shaped membrane is then quenched in a liquid comprised of a solvent that is miscible with the solvent that solubilizes the polyvinylidene chloride copolymer but is immiscible with the polyvinylidene chloride copolymer to form a wet asymmetric polyvinylidene chloride copolymer membrane. The solvents are removed from the wet membrane to form the asymmetric polyvinylidene chloride (PVDC) copolymer membrane. The membrane then may be further heated to form a carbon asymmetric membrane in which the porous support structure and separation layer of the PVDC membrane is maintained. The asymmetric carbon membrane may be useful to separate gases such as olefins from their corresponding paraffins, hydrogen from syngas or cracked gas, natural gas or refinery gas, oxygen/nitrogen, or carbon dioxide and methane.

Stable maintenance of high separation performance of a separation membrane having a separation layer comprising a compact carbon layer is described in addition to a separation membrane having a separation layer comprising a compact carbon layer, wherein particles are attached to the compact carbon layer, recesses are present in the compact carbon layer, and the particles are at least partially stuck in the recesses.

The present invention provides a porous carbon fiber which has an excellent permeation amount and excellent pressure resistance, which is prevented from the occurrence of detachment or cracking at an interface, and which can exhibit excellent properties needed for use as a support for a fluid separation membrane. The present invention is a porous carbon fiber having a bicontinuous porous structure, wherein

the average value R.sub.ave of the R value of the outer surface and the R value of the inside is 1.0 or more and 1.8 or less,

the absolute value ΔR of the difference between the R value of the outer surface and the R value of the inside is 0.05 or less, and

R value is a carbonization progression degree calculated from a Raman spectrum in accordance with the following formula:

R value=(intensity of scattering spectrum at 1360 cm.sup.−1)/(intensity of scattering spectrum at 1600 cm.sup.−1).

An asymmetric hollow fiber (CMS) carbon molecular sieve is made by providing a dope solution comprised of a polvimide and a solvent, at a temperature greater than 250° C. that is less than the storage modulus at a temperature of 250° C., but no more than ten times less as measured using dynamic mechanical thermal analysis from 250° C. to a temperature where the polyimide carbonizes. The polvimide is shaped into a hollow polvimide fiber, the solvent removed and the polyimide hollow fiber is heated to pyroiyze the polvimide and form the asymmetric hollow carbon molecular sieve. The asymmetric hollow fiber carbon molecular sieve has a wall that is defined by an inner surface and outer surface of said fiber and the wall has an inner porous support region extending from the inner surface to an outer raicroporous separation region that extends from the inner porous support region to the outer surface. Surprisingly, when the polyimide has the particular storage modulus characteristics, the method allows for the hollow fiber CMS to be made without any pre-treatmenis or additives to inhibit stractural collapse of the inner microporous region.

An additive manufacturing method for producing a component having at least partially or at least locally a porous material structure includes providing a porous or porosable base material, applying the porous or porosable base material to build up the component, and adjusting a porosity of the porous or porosable base material during the applying.

Disclosed are a CMS membrane, characterized in that it is obtainable by pyrolysis of a polyimide composed of the monomers 1-(4-aminophenyl)-1,3,3-trimethyl-2H-inden-5-amine and 5-(1,3-dioxo-2-benzofuran-5-carbonyl-2-benzofuran-1,3-dione of the following formulae: ##STR00001##
preferably by pyrolysis of the polyimide having the CAS number 62929-02-6, and a supported CMS membrane comprising a CMS membrane obtainable from a polyimide by pyrolysis and a porous support, characterized in that a mesoporous intermediate layer is provided between the CMS membrane and the porous support. Further disclosed are a process for preparing the supported membrane, the use of the membranes for separating gas mixtures or liquid mixtures, an apparatus for gas separation or for liquid separation, and the use of the polyimide for preparing a CMS membrane by pyrolysis.