Provided is an adsorbent used for removing carbon dioxide from a gas containing carbon dioxide, the adsorbent containing cerium oxide, in which a lattice constant of the cerium oxide is 0.5415 nm or more.

Polyamines with lengths carefully tailored to the framework dimensions are appended to metal-organic frameworks such as Mg.sub.2(dobpdc) (dobpdc4-=4,4-dioxidobiphenyl-3,3-dicarboxylate) with the desired loading of one polyamine per two metal sites. The polyamine-appended materials show step-shaped adsorption and desorption profiles due to a cooperative CO.sub.2 adsorption/desorption mechanism. Several disclosed polyamine-appended materials exhibit strong ability to capture CO.sub.2 from various compositions. Increased stability of amines in the framework has been achieved using high molecular weight polyamine molecules that coordinate multiple metal sites in the framework. The preparation of these adsorbents as well as their characterization are provided.

Na.sup.+-SAPO-34 sorbents were ion-exchanged with several individual metal cations for CO.sub.2 absorption at different temperatures (273-348 K) and pressures (<1 atm). In general, the overall adsorption performance of the exchanged materials increased as follows: Ce.sup.3+<Ti.sup.3+<Mg.sup.2+<Ca.sup.2+<Ag.sup.+<Na.sup.+<Sr.sup.2+. The strontium exchanged materials excelled at low-pressure ranges, exhibiting very sharp isotherms slopes at all temperatures. The Sr.sup.2+ species were responsible for the surface strong interaction and the cations were occupying exposed sites (SII) in the materials Chabazite cages. All the sorbent materials exhibited higher affinity for CO.sub.2 over the other gases tested (i.e., CH.sub.4, H.sub.2, N.sub.2 and O.sub.2) due to strong ion-quadrupole interactions. Sr.sup.2+-SAPO-34 sorbents are by far the best option for CO.sub.2 removal from CH.sub.4 mixtures, especially at low concentrations.

A mixed salt composition adapted for use as a sorbent for carbon dioxide removal from a gaseous stream is provided, the composition being in solid form and including magnesium oxide, an alkali metal carbonate, and an alkali metal nitrate, wherein the composition has a molar excess of magnesium characterized by a Mg:X atomic ratio of at least about 3:1, wherein X is the alkali metal. A process for preparing the mixed salt is also provided, the process including mixing a magnesium salt with a solution comprising alkali metal ions, carbonate ions, and nitrate ions to form a slurry or colloid including a solid mixed salt including magnesium carbonate; separating the solid mixed salt from the slurry or colloid to form a wet cake; drying the wet cake to form a dry cake including the solid mixed salt; and calcining the dry cake to form a mixed salt sorbent.

Disclosed herein are novel RHO zeolites useful as kinetically selective adsorbents for oxygen and/or nitrogen. The adsorbents can be used in pressure swing adsorption processes for selectively adsorbing oxygen and/or nitrogen from feed streams such as an air stream or crude argon stream. Also disclosed are novel methods of preparing RHO zeolites, including in particular mixed-cation RHO zeolites.

Methods of designing zeolite materials for adsorption of CO.sub.2. Zeolite materials and processes for CO.sub.2 adsorption using zeolite materials.

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.

A method and apparatus for removing a volatile component from a mixture are disclosed. The method and apparatus employ a crosslinked elastomer with a glass transition temperature +25 C. as the sorbent.

A method and system of depressurizing a molecular sieve used in ethanol production is shown and described. The method and system utilizes a vapor mixing condenser that receives a vapor sieve feed from the molecular sieve during the depressurization cycle. The vapor from the molecular sieve during the pressurization cycle is used to heat the 190-proof product flow. The heated product flow is diverted directly to the 190-proof product vaporizer, which increases the input product flow temperature to the vaporizer, thereby reducing the amount of heat needed to vaporize the 190-proof product flow. The reduction in heat needed reduces energy costs and increases equipment life.

Primary, secondary (1?,2?) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for CO.sub.2 capture applications. Increasing the size of the alkyl group on the secondary amine enhances the stability to diamine volatilization from the metal sites. Two-step adsorption/desorption profiles are overcome by minimizing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg.sub.2(dotpdc) (dotpdc.sup.4?=4,4-dioxido-[1,1:4,1-terphenyl]-3,3-dicarboxylate), yields diamine-appended adsorbents displaying a single CO.sub.2 adsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg.sub.2(pc-dobpdc) (pc-dobpdc.sup.4?=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single CO.sub.2 adsorption step with bulky diamines. By relieving steric interactions between adjacent ammonium carbamate chains, these frameworks enable step-shaped CO.sub.2 adsorption, decreased water co-adsorption, and increased stability to diamine loss. Variants of Mg.sub.2(dotpdc) and Mg.sub.2(pc-dobpdc) functionalized with large diamines such as N-(n-heptyl)ethylenediamine have utility as adsorbents for carbon capture applications.