University of California

Exxonmobil Research and Engineering Company

Exxonmobil Technology and Engineering Company

Phillip J Milner

Jeffrey R Long

Rebecca L Siegelman

Simon Christopher Weston

Jeffrey D Martell

Joseph M Falkowski

Eugene J Kim

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 COadsorption capacity of greater than 2.50 mmol/g at 150 mbar COat 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(dobpdc), where dobpdcis 4,4'-dioxidobiphenyl-3,3′-dicarboxylate. Example applications for the adsorption material are removal of carbon dioxide from flue gas and biogasses.

Amine-appended metal-organic frameworks exhibiting a new adsorption mechanism for carbon dioxide separations

Primary, secondary (1&#xb0;,2&#xb0;) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for COcapture 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 minimzing steric interactions between adjacent ammonium carbamate chains. For instance, the isoreticularly expanded framework Mg(dotpdc) (dotpdc=4,4&#x2033;-dioxido-[1,1':4&#x2032;,1&#x2033;-terphenyl]-3,3&#x2033;-dicarboxylate), yields diamine-appended adsorbents displaying a single COadsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg(pc-dobpdc) (pc-dobpdc=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single COadsorption step with bulky diamines. By relieving steric interactions between adjacent ammonium carbamate chains, these frameworks enable step-shaped COadsorption, decreased water co-adsorption, and increased stability to diamine loss. Variants of Mg(dotpdc) and Mg(pc-dobpdc) functionalized with large diamines such as N-(n-heptyl)ethylenediamine have utility as adsorbents for carbon capture applications.

Overcoming two carbon dioxide adsorption steps in diamine-appended metal organic frameworks

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 COadsorption capacity of greater than 2.50 mmol/g at 150 mbar COat 40&#xb0; C. Moreover, the adsorbent is configured to regenerate at less than 120&#xb0; C. An example ligand is diamine 2,2-dimethyl-1,3-propanediamine. An example of the metal-organic framework is Mg(dobpdc), where dobpdcis 4,4'-dioxidobiphenyl-3,3&#x2032;-dicarboxylate. Example applications for the adsorption material are removal of carbon dioxide from flue gas and biogasses.

Polyamines with lengths carefully tailored to the framework dimensions are appended to metal-organic frameworks such as Mg(dobpdc) (dobpdc4-=4,4'-dioxidobiphenyl-3,3&#x2032;-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 COadsorption/desorption mechanism. Several disclosed polyamine-appended materials exhibit strong ability to capture COfrom 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.

Polyamine-appended metal-organic frameworks for carbon dioxide separations

Primary, secondary (1&#xba;,2&#xba;) alkylethylenediamine- and alkylpropylenediamine-appended variants of metal-organic framework are provided for COcapture 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(dotpdc) (dotpdc=4,4&#x2033;-dioxido-[1,1':4&#x2032;,1&#x2033;-terphenyl]-3,3&#x2033;-dicarboxylate), yields diamine-appended adsorbents displaying a single COadsorption step. Further, use of the isomeric framework Mg-IRMOF-74-II or Mg(pc-dobpdc) (pc-dobpdc=3,3-dioxidobiphenyl-4,4-dicarboxylate, pc=para-carboxylate) also leads to a single COadsorption step with bulky diamines. By relieving steric interactions between adjacent ammonium carbamate chains, these frameworks enable step-shaped COadsorption, decreased water co-adsorption, and increased stability to diamine loss. Variants of Mg(dotpdc) and Mg(pc-dobpdc) functionalized with large diamines such as N-(n-heptyl)ethylenediamine have utility as adsorbents for carbon capture applications.

Overcoming two carbon dioxide adsorption steps in diamine-appended metal-organic frameworks

Achieving the selective and reversible adsorption of COfrom humid, low partial pressures streams such as the flue gas resulting from the combustion of natural gas in combined cycle power plants (4% CO) is challenging due to the need for high thermal, oxidative, and hydrolytic stability as well as moderate regeneration conditions to reduce the energy of adsorption/desorption cycling. Appending cyclic primary, secondary diamines, exemplified by 2-(aminomethyl)piperidine (2-ampd), to the metal-organic frameworks Mg(dobpdc) (dobpdc=4,4-dioxidobiphenyl-3,3-dicarboxylate), Mg(dotpdc) (dotpdc=4,4&#x2033;-dioxido-[1,1':4&#x2032;,1&#x2033;-terphenyl]-3,3&#x2033;-dicarboxylate) or Mg(pc-dobpdc) (pc-dobpdc=dioxidobiphenyl-4,4&#x2032;-dicarboxylate) produces adsorbents of the classes EMM-44, EMM-45, and EMM-46, respectively, that display step-shaped adsorption of COat the partial pressures required for 90% capture from natural gas flue gas at temperatures up to or exceeding 60&#xb0; C. Using a cyclic diamine in place of a diamine functionalized with bulky alkyl groups enables fast adsorption/desorption kinetics with sharp COadsorption and desorption steps.

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Phillip J Milner