A system and process for selectively separating H.sub.2S from a gas mixture which also comprises CO.sub.2 is disclosed. A water recycle stream is fed to the absorber in order to create a higher concentration absorbent above the recycle feed and having a greater H.sub.2S selectivity at lower acid gas loadings, and a more dilute absorbent below the recycle feed and having a greater H.sub.2S selectivity at higher acid gas loadings. Also disclosed is a system and process for selectively separating H.sub.2S by utilizing two different absorbents, one absorbent for the upper section of the absorber, tailored to have a greater H.sub.2S selectivity at lower acid gas loadings, and a second absorbent for the lower section of the absorber, tailored to have a greater H.sub.2S selectivity at higher acid gas loadings.

A method for operating an adsorption-based system for removing water and potentially other components from a feed stream. The system includes at least two dehydration units each comprising an adsorption bed. The method includes the steps of: i) obtaining process data from one or more sensors at a predetermined time resolution, the sensors at least comprising at least one moisture sensor at a specified location in each of the dehydration units; ii) dehydrating the feed stream by operating the adsorption-based system in regenerative mode, wherein at least one active unit of the at least two dehydration units is in an adsorption cycle, and wherein at least another one of the at least two dehydration units is being regenerated; iii) estimating an adsorption bed water adsorption capacity during every adsorption cycle; and iv) using the process data to update the estimated adsorption bed water adsorption capacity.

This disclosure relates to the adsorption and separation of nitrogen in a feed stream (e.g., natural gas) using zeolite ITQ-55 as the adsorbent. A process is disclosed for removing impurities such as nitrogen while producing a high pressure hydrocarbon product. The process involves passing the feed stream through a bed of an adsorbent comprising zeolite ITQ-55 to adsorb nitrogen from the feed stream, thereby producing a product stream depleted in nitrogen at pressure as feed condition without need of recompression. The zeolite ITQ-55 has a mean crystal particle size within the range of from about 0.01 microns to about 40 microns. The feed stream is exposed to the zeolite ITQ-55 at effective conditions for performing a kinetic separation, in which the kinetic separation exhibits greater kinetic selectivity for nitrogen than for methane. The system and method of this disclosure are particularly suitable for use with feed streams utilizing rapid cycle PSA operations.

Provided are apparatus and systems for performing a swing adsorption process. This swing adsorption process may involve performing a startup mode process prior to beginning a normal operation mode process to remove contaminants from a gaseous feed stream. The startup mode process may be utilized for swing adsorption processes, such as TSA and/or PSA, which are utilized to remove one or more contaminants from a gaseous feed stream.

An adsorption material is disclosed that comprises a metal-organic framework and a plurality of ligands. The metal-organic framework comprising a plurality of metal ions. Each respective ligand in the plurality of ligands is amine appended to a respective metal ion in the plurality of metal ions of the metal-organic framework. Each respective ligand in the plurality of ligands comprises a substituted 1,3-propanediamine. The adsorbent has a CO.sub.2 adsorption capacity of greater than 2.50 mmol/g at 150 mbar CO.sub.2 at 40° C. Moreover, the adsorbent is configured to regenerate at less than 120° C. An example ligand is diamine 2,2-dimethyl-1,3-propanediamine. An example of the metal-organic framework is Mg.sub.2(dobpdc), where dobpdc.sup.4− is 4,4′-dioxidobiphenyl-3,3′-dicarboxylate. Example applications for the adsorption material are removal of carbon dioxide from flue gas and biogasses.

Acid gas compounds are removed from a process gas such as, for example, syngas or natural gas, by flowing a feed gas into a desulfurization unit to remove a substantial fraction of sulfur compounds from the feed gas and flowing the resulting desulfurized gas into a CO.sub.2 removal unit to remove a substantial fraction of CO.sub.2 from the desulfurized gas.

The present disclosure is directed to a potassium-form MER framework type zeolite, a MER framework type zeolite having a stick-like morphology, wherein the potassium is present as K.sup.+ in extra-framework locations. The zeolite is essentially free of an extra-framework cation other than potassium.

A method for production of renewable natural gas (RNG) from biogases containing volatile organic compounds (VOCs) combines temperature swing adsorption (TSA) for removal of VOCs, a form of pressure swing adsorption (PSA) for nitrogen separation, and membrane gas separation technology for carbon dioxide removal. TSA systems may improve removal of VOCs relative to PSA systems, may reduce RNG plant operating costs, and may simplify RNG plant operation. Methane recovery may be improved by using equilibrium PSA systems instead of dynamic PSA systems for methane separation.

Systems and methods for controlling an amine contactor are provided. An exemplary method includes determining a pickup ratio for a solvent in the contactor, measuring a temperature of a lower tray of the contactor, adjusting the pickup ratio based, at least in part, on the temperature, and adjusting a flow rate for an injection of lean solvent into the contactor based, at least in part, on the pickup ratio.

A natural gas refining apparatus including a first separation membrane unit including a first separation membrane; and a second separation membrane unit provided in a subsequent stage of the first separation membrane unit. The second separation membrane unit includes a second separation membrane that allows an amine solution to circulate through the second separation membrane unit, and the natural gas refining apparatus refines raw natural gas containing CO.sub.2 by passing the raw natural gas through the first and second separation membrane units, separating CO.sub.2-rich gas with the first and second separation membranes, and absorbing CO.sub.2 with the amine solution circulating through the second separation membrane unit.