The present invention generally relates to a pressure swing adsorption process for separating an adsorbate impurity from a feed stream comprising product gas, said process comprising feeding the feed stream to an adsorbent bed at a pressure of from about 60 psig to 2000 psig, wherein said adsorbent bed comprises adsorbent having: An isosteric heat of adsorption of from about 5 kJ/mol to about 30 kJ/mol, as determined by the LRC method, for the adsorbate, and an equivalent 65 kJ/mol or less isosteric heat of adsorption for the product,
wherein the adsorbent has a rate of adsorption for the adsorbate impurity that is at least 10 times greater than the rate of adsorption for the product gas as determined by the TGA method and recovering said product gas with a reduced a level of said adsorbate impurity. The invention also related to an adsorbent useful in PSA separations, particularly separating N.sub.2 from methane, CO.sub.2 from methane O.sub.2 from N.sub.2 and the like.

An aminal compound is injected into a fluid gas stream including at least one acid gas to reduce the amount of acid gas in the fluid gas stream. Having two reactive sites present in the aminal compound enables a much higher efficiency of acid gas capture than a simple alkanolamine, which isn't effective, for example, under dilute circumstances.

The present invention provides a composite body having, on a porous substrate and in the interstices of the substrate that includes fibers, preferably of an electrically nonconductive material, a porous layer (1) composed of oxide particles bonded to one another and partly to the substrate that include at least one oxide selected from oxides of the elements Al, Zr, Ti and Si, preferably selected from Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2 and SiO.sub.2, and having, at least on one side, a further porous layer (2) including oxide particles bonded to one another and partly to layer (1) that include at least one oxide selected from oxides of the elements Al, Zr, Ti and Si, preferably selected from Al.sub.2O.sub.3, ZrO.sub.2, TiO.sub.2 and SiO.sub.2, where the oxide particles present in layer (1) have a greater median particle size than the oxide particles present in layer (2), which is characterized in that the median particle size (d.sub.50) of the oxide particles in layer (1) is from 0.5 to 4 μm and the median particle size (d.sub.50) of the oxide particles in layer (2) is from 0.015 to 0.15 μm, preferably 0.04 to 0.06 μm, a process for producing corresponding composite bodies and for the use thereof, especially in gas separation.

Porous compositions such as flexible polymers with side chain porosity are generally provided. In some embodiments, the composition comprises a flexible polymer backbone and a plurality of rigid side chains. In some embodiments, the rigid side chains form pores. In some embodiments, the rigid side chains may comprise two or more [2.2.2] bicyclic cores (e.g., formed by a ring opening metathesis polymerization. The compounds and methods described herein may be useful in various applications including, for example, gas separation.

An apparatus and process for separating a gas mixture is disclosed. The apparatus includes a first membrane stage, a second membrane stage, and a third membrane stage. The first membrane stage includes a first gas separation membrane configured to separate the gas mixture into a first retentate stream and a first permeate stream. The second membrane stage includes a second gas separation membrane configured to separate the first permeate stream into a second retentate stream and a second permeate stream. The second retentate stream of the second membrane stage is recycled back to connect with the first retentate stream to form a mixed fluid stream. The third membrane stage includes a third gas separation membrane configured to separate the mixed fluid stream into a third retentate stream and a third permeate stream, and the third retentate stream is configured to be withdrawn as a product or discarded.

A design is provided to convert a gas subcooled process plant to a recycle split vapor process for recovering ethane and propane from natural gas. When in operation, the recovery of ethane and propane can exceed 97 to 99 wt. % of the stream being processed. A second smaller demethanizer column is added to the gas subcooled process plant as well as the addition of several cryogenic pumps.

Disclosed are a heterogeneous zeolite membrane and a method of preparing the same, and more particularly a heterogeneous zeolite membrane that has CHA and DDR zeolite structures by growing seed particles into a crystal structure different from that of the zeolite membrane and can thus separate CO.sub.2/N.sub.2 and CO.sub.2/CH.sub.4 even under wet conditions, a method of preparing the same, and a method of capturing and removing carbon dioxide using the membrane.

A multi-stage system comprising a digester, a bioreactor, a scrubber, a biofilter, and a membrane filter extracts and purifies biogas from a wastewater feed. The digester separates raw biogas from wastewater, the wastewater is then purified with a three-stage bacterial process in a bioreactor. The scrubber receives raw biogas from the digester under pressure, dissolving waste gases and purifying the methane, which can be further condensed and purified in the membrane filter. The bioreactor receives waste gases from the scrubber and membrane filter, with the ammonia portion of the waste gases rising through water from the bioreactor and being converted by annamox bacteria into nitrogen gas. The multiply recycled gas and water feeds produce a biogas having high purity and reduced atmospheric emissions of waste gases.

A thin film composite gas separation membrane comprising a polyether block amide copolymer coating layer and a nanoporous asymmetric support membrane with nanopores on the skin layer surface of the support membrane and gelatin polymers inside the nanopores on the skin layer surface of the support membrane. A method for making the thin film composite gas separation membrane is provided as well as the use of the membrane for a variety of separations such as separations of hydrogen sulfide and carbon dioxide from natural gas, carbon dioxide removal from flue gas, fuel gas conditioning, hydrogen/methane, polar molecules, and ammonia mixtures with methane, nitrogen or hydrogen and other light gases separations, but also for natural gas liquids recovery and hydrogen sulfide and carbon dioxide removal from natural gas in a single step.

Gas separation membranes are provided and more particularly, a series of addition-type and ROMP type polynorbornenes with substituents derived from Mizoroki-Heck reactions are provided and have particular utility as gas separation membranes for natural gas upgrading.