Application of a high-throughput analyzer in evaluating solid adsorbents for post-combustion carbon capture via multicomponent adsorption of CO2, N2, and H2O.

Despite the large number of metal-organic frameworks that have been studied in the context of post-combustion carbon capture, adsorption equilibria of gas mixtures including CO2, N2, and H2O, which are the three biggest components of the flue gas emanating from a coal- or natural gas-fired power plant, have never been reported. Here, we disclose the design and validation of a high-throughput multicomponent adsorption instrument that can measure equilibrium adsorption isotherms for mixtures of gases at conditions that are representative of an actual flue gas from a power plant. This instrument is used to study 15 different metal-organic frameworks, zeolites, mesoporous silicas, and activated carbons representative of the broad range of solid adsorbents that have received attention for CO2 capture. While the multicomponent results presented in this work provide many interesting fundamental insights, only adsorbents functionalized with alkylamines are shown to have any significant CO2 capacity in the presence of N2 and H2O at equilibrium partial pressures similar to those expected in a carbon capture process. Most significantly, the amine-appended metal organic framework mmen-Mg2(dobpdc) (mmen = N,N'-dimethylethylenediamine, dobpdc (4-) = 4,4'-dioxido-3,3'-biphenyldicarboxylate) exhibits a record CO2 capacity of 4.2 ± 0.2 mmol/g (16 wt %) at 0.1 bar and 40 °C in the presence of a high partial pressure of H2O.

Hydrogen storage materials discovery via high throughput ball milling and gas sorption.

The lack of a high capacity hydrogen storage material is a major barrier to the implementation of the hydrogen economy. To accelerate discovery of such materials, we have developed a high-throughput workflow for screening of hydrogen storage materials in which candidate materials are synthesized and characterized via highly parallel ball mills and volumetric gas sorption instruments, respectively. The workflow was used to identify mixed imides with significantly enhanced absorption rates relative to Li2Mg(NH)2. The most promising material, 2LiNH2:MgH2 + 5 atom % LiBH4 + 0.5 atom % La, exhibits the best balance of absorption rate, capacity, and cycle-life, absorbing >4 wt % H2 in 1 h at 120 °C after 11 absorption-desorption cycles.

Generation and O2 adsorption studies of the microporous magnets CsNi[Cr(CN)6] (T(C) = 75 K) and Cr3[Cr(CN)6]2 x 6 H2O (T(N) = 219 K).

Dehydration of the Prussian blue analogues CsNi[Cr(CN)(6)] x 2 H(2)O (1) and Cr(3)[Cr(CN)(6)](2) x 10 H(2)O (2) affords two new microporous magnets: CsNi[Cr(CN)(6)] (1d) and Cr(3)[Cr(CN)(6)](2) x 6 H(2)O (2d). Compounds 1d and 2d maintain the Prussian blue structure, and N(2) adsorption measurements at 77 K show them to be microporous with BET surface areas of 360 and 400 m(2)/g, respectively. Both solids largely retain the magnetic properties of their parent hydrates, with 1d ordering at 75 K and 2d ordering at 219 K, by far the highest ordering temperature yet observed for a microporous magnet. The compounds further show unexpected changes in their magnetic properties upon adsorption of O(2). In 2d, adsorption of O(2) results in a reversible decrease in the magnetic moment of the system, as well as a reduction of the coercivity from 110 to 10 G and of the remnant magnetization from 1200 to 400 emu.G/mol, indicating a net antiferromagnetic interaction between O(2) and the framework. In 1d, adsorption of O(2) instead results in a reversible increase in the magnetic moment of the system, indicating a net ferromagnetic interaction between O(2) and the framework. Together, the results suggest that ferromagnetic exchange coupling between O(2) and the [Cr(CN)(6)](3-) units provides the predominate magnetic interaction of the adsorbate with the framework.

Matrix isolation chemistry in a porous metal-organic framework: photochemical substitutions of N2 and H2 in Zn4O[(eta6-1,4-benzenedicarboxylate)Cr(CO)3]3.

Reaction of the microporous metal-organic framework Zn4O(BDC)3 (BDC2- = 1,4-benzenedicarboxylate) with Cr(CO)6 at 140 degrees C in a 6:1 mixture of dibutylether and THF affords Zn4O[(BDC)Cr(CO)3]3 (1). This compound retains the porous cubic structure of the parent framework, but features Cr(CO)3 groups attached in an eta6 fashion to all of the benzene rings. Compound 1 is also microporous, exhibiting a BET surface area of 2130 m2/g. It can be fully decarbonylated by heating at 200 degrees C, but the resulting gray solid (2) shows little affinity for N2 or H2 at 298 K, suggesting aggregation of the chromium atoms. In contrast, photolysis of 1 using 450-nm light in an atmosphere of N2 or H2 produces solids with infrared spectra indicative of Zn4O[(BDC)Cr(CO)2(N2)]3 (3) and Zn4O[(BDC)Cr(CO)2(H2)]3 (4). Under an N2 atmosphere, compound 4 completely converts into compound 3 over the course of 12 h, demonstrating the lability of the Cr0-H2 bond. Owing to isolation of the metal centers within the rigid, evacuable framework structures, the N2- and H2-substituted compounds show greatly enhanced stability relative to molecular analogues generated in frozen gas matrices or supercritical fluid solutions.

Hydrogen adsorption in dehydrated variants of the cyano-bridged framework compounds A2Zn3[Fe(CN)6]2.xH2O (A = H, Li, Na, K, Rb).

The impact of coordinatively-unsaturated alkali-metal ions on hydrogen adsorption is studied in dehydrated variants of the compounds A(2)Zn(3)[Fe(CN)(6)](2).xH(2)O (A = H, Li, Na, K, Rb), revealing maximum adsorption enthalpies that vary from 7.7 kJ mol(-1) for A = Na to 9.0 kJ mol(-1) for A = K.

Hydrogen storage in the dehydrated prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn).

The porosity and hydrogen storage properties for the dehydrated Prussian blue analogues M3[Co(CN)6]2 (M = Mn, Fe, Co, Ni, Cu, Zn) are reported. Argon sorption isotherms measured at 87 K afford BET surface areas ranging from 560 m2/g for Ni3[Co(CN)6]2 to 870 m2/g for Mn3[Co(CN)6]2; the latter value is comparable to the highest surface area reported for any known zeolite. All six compounds show significant hydrogen sorption at 77 K and 890 Torr, varying from 1.4 wt % and 0.018 kg H2/L for Zn3[Co(CN)6]2 to 1.8 wt % and 0.025 kg H2/L for Cu3[Co(CN)6]2. Fits to the sorption data employing the Langmuir-Freundlich equation give maximum uptake quantities, resulting in a predicted storage capacity of 2.1 wt % and 0.029 kg H2/L for Cu3[Co(CN)6]2 at saturation. Enthalpies of adsorption for the frameworks were calculated from hydrogen isotherms measured at 77 and 87 K and found to increase with M varying in the order Mn < Zn < Fe < Co < Cu < Ni. In all cases, the binding enthalpies, which lie in the range of 5.3-7.4 kJ/mol, are higher than the 4.7-5.2 kJ/mol measured for Zn4O(1,4-benzenedicarboxylate)3.

Design, synthesis, and biological activity of potent and selective inhibitors of mast cell tryptase.

A new series of novel mast cell tryptase inhibitors is reported, which features the use of an indole structure as the hydrophobic substituent on a m-benzylaminepiperidine template. The best members of this series display good in vitro activity and excellent selectivity against other serine proteases.