Systems and processes for use of concentric adsorbent beds with rotary valve assemblies are provided.

Functionalized zeolites, including a zeolite substrate and a self-assembled monolayer of a phosphonic acid on a surface of the zeolite substrate, are disclosed, as are methods of making and using the functionalized zeolites. The disclosed methods and compositions have various applications, including in the use of molecular sieves to separate small-molecule gases from mixtures thereof. Gas adsorption selectivities and diffusion rates of the functionalized zeolites may be tuned or selected according to the disclosed methods.

Process and apparatuses for purifying a feed stream containing CO.sub.2 and predominantly hydrogen are provided. In an embodiment, the process includes passing the feed stream through a multilayer adsorbent bed comprising a first adsorbent section, a second adsorbent section downstream from the first adsorbent section and a third adsorbent section downstream from the second adsorbent section. The first adsorbent section comprises an activated carbon layer, the second adsorbent section comprises a layer of molecular sieve of the faujasite structure type with a Si/Al atomic ratio of from 1.5 to 8.0 and the third adsorbent section comprises a layer of molecular sieve of the faujasite structure type with a Si/Al atomic ratio of from 1.0 to 1.5. At least one of N.sub.2, CO.sub.2, CH.sub.4 and CO is adsorbed from the feed stream and a purified hydrogen product is recovered from the multilayer adsorbent bed.

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 process is disclosed for producing hydrogen for a hydrogen consuming process comprising obtaining a gas stream containing hydrogen from a steam reforming hydrogen plant, sending the gas stream to a pressure swing adsorption unit to be separated into a hydrogen stream and a fuel gas stream; purging the pressure swing adsorption unit with an external purge gas stream from a hydroprocessing unit off gas; treating the off gas with a thermal swing adsorption unit to remove water and other impurities prior to purging the pressure swing adsorption unit; and using a protective adsorbent layer in the pressure swing adsorption unit at the product-hydrogen end of the bed to adsorb impurities from the external purge gas.

The invention provides a process for producing hydrogen for a hydrogen consuming process comprising obtaining a net gas stream containing hydrogen, compressing the gas stream to a pressure of 20.7 to 68.9 bar (300 to 1000 psig) to produce a compressed gas stream; sending the compressed gas stream to a pressure swing adsorption unit to be separated into a hydrogen stream and a fuel gas stream; purging the pressure swing adsorption unit with an external purge gas stream from a hydroprocessing unit off gas; treating the off gas with a thermal swing adsorption unit to remove water and other impurities prior to purging the pressure swing adsorption unit, and using a protective adsorbent layer in the pressure swing adsorption unit to adsorb impurities from the external purge gas.

Helium-containing natural gas is processed with three gas separation stages to produce a natural gas product and a Helium-containing gas that may be injected into the reservoir from which the Helium-containing natural gas is obtained. A permeate from the first gas separation membrane stage is compressed and fed to the second gas membrane stage. The permeate from the second gas separation membrane stage is recovered as the Helium-containing gas that may be injected into the reservoir. The non-permeate from the second gas separation membrane stage is fed to the third gas separation membrane stage. The non-permeate from the first gas separation stage is a natural gas product. A permeate from the third gas separation membrane stage is combined with a non-permeate from the first gas separation membrane stage before it is compressed and fed to the second gas separation membrane stage. A non-permeate from the third gas separation membrane stage is fed to the first gas separation membrane stage along with the Helium-containing natural gas.

A process is disclosed for increasing hydrogen recovery in an integrated refinery and petrochemical complex in which natural gas is used as a co-purge gas in a pressure swing adsorption unit. This natural gas is recovered in tail gas from the pressure swing adsorption unit. This process is useful for refinery off-gas and partial oxidation feeds.

One or more embodiments relate to providing substrate for separating a first gas component from a gaseous mixture, said substrate comprising a benzimidazole-linked polymer. Also provided is a method for synthesizing a substrate for separating a first gas component from a gaseous mixture, the method comprising performing a free condensation reaction between an aryl-o-diamine and an aryl-aldehyde to yield a benzimidazole-linked polymer. Other embodiments related to providing a CO.sub.2 separation membrane comprising benzimidazole-linked polymer residing within a matrix.

The present invention relates to a process for obtaining pure helium using a first membrane separation stage a second membrane separation stage and a third membrane separation stage. The first membrane separation stage is supplied with a first helium-containing feed mixture, the second membrane separation stage with a second helium-containing feed mixture and the third membrane separation stage with a third helium-containing feed mixture a first permeate and a first retentate are formed in the first membrane separation stage, a second permeate and a second retentate in the second membrane separation stage and a third permeate and a third retentate in the third membrane separation stage. The first feed mixture is formed using at least part of a helium-containing starting mixture. The second feed mixture is formed using at least part of the first permeate. The third feed mixture is formed using at least part of the second permeate. The third permeate is at least partly processed by pressure swing adsorption to obtain pure helium and a residual mixture at least some of the residual mixture is used in the formation of the second or third feed mixture.