Poly[[[tetra­aqua­cobalt(II)]-μ-bipyridine] terephthalate]

The CoII atom in the title complex, {[Co(C10H8N2)(H2O)4](C8H4O4)}n, is coordinated by two N atoms of two bipyridine ligands and four O atoms of four water mol­ecules in an octahedral geometry. The one-dimensional [Co(C10H8N2)(H2O)4]2+ cation chain is further extended into a supra­molecular network via O–H⋯O hydrogen-bond inter­actions. The Co atom lies on a twofold rotation axis; another twofold rotation axis passes through the carboxylate carbon atoms and the attached ring C atoms

An EOF Iteration Approach for Obtaining Homogeneous Radiative Fluxes from Satellites Observations

Conventional observations of climate parameters are sparse in space and/or in time and the representativeness of such information needs to be optimized. Observations from satellites provide improved spatial coverage than point observations however they pose new challenges for obtaining homogeneous coverage. Surface radiative fluxes, the forcing functions of the hydrologic cycle and biogeophysical processes, are now becoming available from global scale satellite observations. They are derived from independent satellite platforms and sensors that differ in temporal and spatial resolution and in the size of the footprint from which information is derived. Data gaps, degraded spatial resolution near boundaries of geostationary satellites, and different viewing geometries in areas of satellite overlap, could result in biased estimates of radiative fluxes. In this study, discussed will be issues related to the sources of inhomogeneity in surface radiative fluxes as derived from satellites; development of an approach to obtain homogeneous data sets; and application of the methodology to the widely used International Satellite Cloud Climatology Project (ISCCP) data that currently serve as a source of information for deriving estimates of surface and top of the atmosphere radiative fluxes. Introduced is an Empirical Orthogonal Function (EOF) iteration scheme for homogenizing the fluxes. The scheme is evaluated in several ways including comparison of the inferred radiative fluxes against ground observations, both before and after the EOF approach is applied. On the average, the latter reduces the rms error by about 2-3 W/m2

A new MOF-5 homologue for selective separation of methane from C₂ hydrocarbons at room temperature

A new MOF-5 homologue compound UTSA-10 has been obtained under solvothermal conditions from a mixture of Zn(NO3)2⋅6H2O and commercially available linker, 2-methylfumaric acid, in N,N-dimethylformamide. The moderate surface area and suitable pore sizes enable the activated UTSA-10a to separate methane from C2 hydrocarbons at room temperature

Single and multicomponent sorption of CO2, CH4 and N-2 in a microporous metal-organic framework

Single and multicomponent fixed-bed adsorption of CO2, N-2, and CH4 on crystals of MOF-508b has been studied in this work. Adsorption equilibrium was measured at temperatures ranging from 303 to 343 K and partial pressures up to 4.5 bar. MOF-508b is very selective for CO2 and the loadings of CH4 and N-2 are practically temperature independent. The Langmuir isotherm model provides a good representation of the equilibrium data. A dynamic model based on the LDF approximation for the mass transfer has been used to describe with good accuracy the adsorption kinetics of single, binary and ternary breakthrough curves. It was found that the intra-crystalline diffusivity for CO2 is one order of magnitude faster than for CH4 and N-2.This work was supported by an Award CHE 0718281 from the National Science Foundation (B.C.), the University of Texas-Pan American (UTPA) through a Faculty Research Council Award (B.C), in part by the Welch Foundation (Grant BG-0017) to the Department of Chemistry at UTPA. J.A.C.S. acknowledges financial support provided by national research grant FCT=POCTI=EQU=60828=2004 and by LSRE financing by FEDER=POCI=2010. P.S.B. acknowledges his Ph.D. scholarship by FCT (SFRH=BD=30994=2006), and L.B. acknowledges Henri Pieper Grant (Institute HEMES Gramme, Belgium) for the financial support

A microporous metal-organic framework for separation of CO2/N-2 and CO2/CH4 by fixed-bed adsorption

A microporous MOF Zn(BDC)(4,4'-Bipy)0.5 (MOF-508b, BDC = 1,4-benzenedicarboxylate, 4,4'-Bipy = 4,4'-bipyridine) was examined for the separation and removal of CO2 from its binary CO2/N-2 and CO2/CH4 and ternary CO2/CH4/N-2 mixtures by fixed-bed adsorption. With one-dimensional pores of about 4.0 x 4.0 angstrom to induce their differential interactions with the three components, MOF-508b exhibits highly selective adsorption to CO2 with the,adsorption capacity of 26.0 wt % at 303 K and 4.5 bar. This is the first example of microporous MOFs for the separation and removal of CO2 from its binary and ternary mixtures by fixed-bed adsorption, establishing the feasibility of the emerging microporous MOFs for their potential. applications in this very important industrial and environmental process

Modeling adsorption equilibria of xylene isomers in a microporous metal–organic framework

Single and multicomponent adsorption equilibria of xylene isomers: o-xylene (o-x), m-xylene (m-x), pxylene (p-x) and ethylbenzene (eb) was investigated on the three dimensional microporous metal–organic framework Zn(BDC)(Dabco)0.5 (BDC = 1,4-benzenedicarboxylate, Dabco = 1,4-diazabicyclo[2.2.2]-octane), MOF 1, in the range of temperatures between 398 and 448 K and partial pressures up to 0.1 bar. The equilibrium data show that a significant amount (around 34 g/100gads at 398 K) of xylene isomers can be adsorbed in MOF 1. The affinity to the adsorbent measured by the Henry’s constants to decreases in the order o-x > m-x > eb > p-x for all temperatures. The zero coverage adsorption enthalpies are all similar and range from 77.4 (eb) to 79.8 kJ/mol (o-x). The Dual-Site Langmuir model (DSL) was used for the interpretation and correlation of the experimental data. The parameters obtained from the pure component isotherms fitting were also used to predict the multicomponent equilibrium data by an extended DSL model. A good agreement was obtained between the predictions and the experimental data. It was also demonstrated that the DSL model is also capable to explain the increase in the isosteric heat of sorption with increasing coverage.José A.C. Silva acknowledges the financial support from Fundação para a Ciência e Tecnologia under Project POCI/EQU/ 60828/2004. Patrick S. Bárcia acknowledges a FCT PhD Grant (SFRH/BD/30994/2006). This work was supported by an Award CHE 0718281 from the NSF (BC)

Fine Tuning the Pore Surface in Zirconium Metal−Organic Frameworks for Selective Ethane/Ethylene Separation

Ethylene is an important chemical feedstock for production of polymers and high-value organic chemicals, and yet its conventional purification process is plagued with high consumption of energy. Metal−organic frameworks (MOFs) provide a suitable adsorption platform for selective ethane/ ethylene separation thanks to their structural diversity, tunable pore characteristics, designable pore sizes, and high pore volumes. Although there are empirical design rules like avoiding open metal sites and creating nonpolar pore surfaces for development of adsorptive MOFs, it is still challenging to design robust MOFs that can realize direct ethane-selective separation. Herein, we systematically designed and synthesized three Zr-MOFs based on the assembly of angular ligands and 12-connected Zr6 clusters that feature the pcu network structure. By changing the size and flexibility of the substituent on the angular ligand, we were able to prevent interpenetration and identified NPF-802, which exhibits good C2H6/C2H4 separation performance that is attributed to the bulky and inert tert-butyl groups of its carbazole ligand. This work provides insights for design of ligands of MOFs with suitable pore environments to address important and challenging gas separations