Evaluation of Metal-Organic Frameworks and Porous Polymer Networks for CO2 -Capture Applications.

This manuscript presents experimental data for 20 adsorption materials (metal-organic frameworks, porous polymer networks, and Zeolite-5A), including CO2 and N2 isotherms and heat capacities. With input from only experimental data, working capacities per energy for each material were calculated. Furthermore, by running seven different carbon-capture scenarios in which the initial flue-gas composition and process temperature was systematically changed, we present a range of performances for each material and quantify how sensitive each is to these varying parameters. The presented calculations provide researchers with a tool to investigate promising carbon-capture materials more easily and completely.

Unprecedented activation and CO2 capture properties of an elastic single-molecule trap.

The activation and CO2 capture properties of a microporous metal-organic framework with elastic single-molecule traps were systematically investigated. This material shows a unique low-energy gas-purge activation capability, high CO2 adsorption selectivities over various gases and optimized working capacities per energy of 2.9 mmol kJ(-1) at 128 °C.

High-throughput analytical model to evaluate materials for temperature swing adsorption processes.

In order for any material to be considered in a post-combustion carbon capture technology, it must have high working capacities of CO2 from flue gas and be regenerable using as little energy as possible. Shown here is an easy to use method to calculate both working capacities and regeneration energies and thereby predict optimal desorption conditions for any material.

Porous materials with pre-designed single-molecule traps for CO2 selective adsorption.

Despite tremendous efforts, precise control in the synthesis of porous materials with pre-designed pore properties for desired applications remains challenging. Newly emerged porous metal-organic materials, such as metal-organic polyhedra and metal-organic frameworks, are amenable to design and property tuning, enabling precise control of functionality by accurate design of structures at the molecular level. Here we propose and validate, both experimentally and computationally, a precisely designed cavity, termed a 'single-molecule trap', with the desired size and properties suitable for trapping target CO(2) molecules. Such a single-molecule trap can strengthen CO(2)-host interactions without evoking chemical bonding, thus showing potential for CO(2) capture. Molecular single-molecule traps in the form of metal-organic polyhedra are designed, synthesised and tested for selective adsorption of CO(2) over N(2) and CH(4), demonstrating the trapping effect. Building these pre-designed single-molecule traps into extended frameworks yields metal-organic frameworks with efficient mass transfer, whereas the CO(2) selective adsorption nature of single-molecule traps is preserved.

Low-energy selective capture of carbon dioxide by a pre-designed elastic single-molecule trap.

Single-molecule trap: Easy activation of the water-stable metal-organic framework PCN-200 provides a new route to low-energy selective CO(2) capture through stimuli-responsive adsorption behavior. This elastic CO(2) trapping effect was confirmed by single-component and binary gas-adsorption isotherms and crystallographic determination.

A novel MOF with mesoporous cages for kinetic trapping of hydrogen.

A stable MOF, assigned PCN-105, with two types of mesoporous cages, has been prepared by using a new multidentate flexible ligand with amine functional groups, and PCN-105 exhibits a marked N(2), O(2), Ar and H(2) hysteretic behaviour.

Sulfonate-grafted porous polymer networks for preferential CO2 adsorption at low pressure.

A porous polymer network (PPN) grafted with sulfonic acid (PPN-6-SO(3)H) and its lithium salt (PPN-6-SO(3)Li) exhibit significant increases in isosteric heats of CO(2) adsorption and CO(2)-uptake capacities. IAST calculations using single-component-isotherm data and a 15/85 CO(2)/N(2) ratio at 295 K and 1 bar revealed that the sulfonate-grafted PPN-6 networks show exceptionally high adsorption selectivity for CO(2) over N(2) (155 and 414 for PPN-6-SO(3)H and PPN-6-SO(3)Li, respectively). Since these PPNs also possess ultrahigh physicochemical stability, practical applications in postcombustion capture of CO(2) lie well within the realm of possibility.

Functional mesoporous metal-organic frameworks for the capture of heavy metal ions and size-selective catalysis.

By using Zn(4)O(CO(2))(6) as secondary building units (SBUs) and two extended ligands containing amino functional groups, TATAB and BTATB (TATAB = 4,4',4''-s-triazine-1,3,5-triyltri-p-aminobenzoate and BTATB = 4,4',4''-(benzene-1,3,5-triyltris(azanediyl))tribenzoate), two isostructural mesoporous metal-organic frameworks (MOFs) with cavities up to 2.73 nm, designated as PCN-100 and PCN-101 (PCN represents porous coordination network), have been synthesized. N(2) sorption isotherms of both PCN-100 and -101 showed typical type IV behavior, indicating their mesoporous nature. The TATAB ligand that comprises PCN-100 was employed to capture heavy metal ions (Cd(II) and Hg(II)) by constructing complexes within the pores with a possible coordination mode similar to that found in aminopyridinato complexes. This reveals that mesoporous materials such as PCN-100 can be applied in the elimination of heavy metal ions from waste liquid. In addition, both PCNs-100 and -101 exhibit size-selective catalytic activity toward the Knoevenagel condensation reaction.