Understanding the adsorption mechanism of noble gases Kr and Xe in CPO-27-Ni, CPO-27-Mg, and ZIF-8.

An experimental study of Xe and Kr adsorption in metal-organic frameworks CPO-27-Ni, CPO-27-Mg, and ZIF-8 was carried out. In situ synchrotron X-ray powder diffraction experiments allowed precise determination of the adsorption sites and sequence of their filling with increasing of gas pressure at different temperatures. Structural investigations were used for interpretation of gas adsorption measurements.

Exceptional gravimetric and volumetric CO2 uptake in a palladated NbO-type MOF utilizing cooperative acidic and basic, metal-CO2 interactions.

A novel NbO-type MOF is reported based on a palladated organic linker, showing a remarkable gravimetric and volumetric CO2 uptake, reaching 201.8 cm(3) g(-1) (9.0 mmol g(-1), 39.7 wt%) and 187.8 cm(3) cm(-3) at 273 K and 1 bar, respectively. Accurate theoretical calculations revealed that the exceptional CO2 uptake is due to the combination of Lewis base Pd(ii)-CO2 (24.3 kJ mol(-1)) and Lewis acid Cu(ii)-CO2 (30.3 kJ mol(-1)) interactions, as well as synergistic pore size effects.

Highly loaded and thermally stable Cu-containing mesoporous silica-active catalyst for the NO + CO reaction.

We report the synthesis of a highly loaded and thermally stable Cu-containing mesoporous silica, which was developed by making use of poly(acrylic acid) (Pac) assembled with surfactant (C(16)TAB), as template. On this backbone, TEOS and Cu(II) hydrolysis takes place leading to the development of the final mesostructure. Poly(acrylic acid) is used not only as a micelle structural component but also as a complexation agent for Cu(II) species resulting in high metal loading and increased thermal stability of the mesoporous network. The original uncalcined material possesses hexagonal ordering, while upon calcination it is transformed into a wormlike mesoporous network with metal loading >14 wt % Cu. An evaluation of its performance as heterogeneous catalyst in NO reduction by CO shows catalytic activity comparable with that of noble metal catalysts. Complete NO conversion, with >90% selectivity to N(2), was achieved between 190 and 200 degrees C. The material retained its structure and catalytic activity after 24-h testing at the maximum catalytic conversion of NO and CO.

Variation of surface properties and textural features of spinel ZnAl2O4 and perovskite LaMnO3 nanoparticles prepared via CTAB-butanol-octane-nitrate salt microemulsions in the reverse and bicontinuous states.

Two binary oxides, a spinel, ZnAl2O4, and a typical perovskite, LaMnO3, have been prepared via CTAB-1-butanol-n-octane-nitrate salt microemulsion in the reverse and bicontinuous states. The exact point of the reverse and bicontinuous states of the microemulsion used in the synthesis was determined by conductivity experiments. The materials obtained after heating at 800 degrees C were characterized by XRD analysis for their crystal structure, N2 porosimetry for their surface area and porosity, and SEM and TEM photography for their texture. The ZnAl2O4 spinel obtained via the reverse microemulsion appears in SEM in a more fragmented form and with a higher specific surface area (143.7 m(2)g(-1)), compared to the corresponding solid prepared via the bicontinuous microemulsion, which appears more robust with lower surface area (126.7 m(2)g(-1)). Nevertheless both materials reveal in TEM a sponge-like structure. The perovskite materials LaMnO3 prepared via the reverse microemulsion showed in SEM a peculiar doughnut-like texture, each doughnut-like secondary particle having a diameter of 2 microm. The corresponding sample developed via the bicontinuous microemulsion showed in SEM uniform secondary particles of size approximately 0.2 microm. Both perovskite samples LaMnO3 appear well crystallized with relative low surface areas, 23.7 m(2)g(-1) for the reverse sample and 10.9 m(2)g(-1) for the bicontinuous one. The TEM photographs reveal that both of them, of reversed and bicontinuous origin, are made up of primary nanoparticles in the size range 40-100 nm. In SEM those materials showed a different secondary structure.

Varied pore organization in mesostructured semiconductors based on the [SnSe4](4-) anion.

Open framework metal chalcogenide solids, with pore sizes in the nano- and mesoscale, are of potentially broad technological and fundamental interest in research areas ranging from optoelectronics to the physics of quantum confinement. Although there have been significant advances in the design and synthesis of mesostructured silicas, the construction of their non-oxidic analogues still remains a challenge. Here we describe a synthetic strategy that allows the preparation of a large class of mesoporous materials based on supramolecular assembly of tetrahedral Zintl anions [SnSe4]4- with transition metals in the presence of cetylpyridinium (CP) surfactant molecules. These mesostructured semiconducting selenide materials are of the general formulae (CP)4-2xMxSnSe4 (where 1.0 < x < 1.3; M=Mn, Fe, Co, Zn, Cd, Hg). The resulting materials are open framework chalcogenides and form mesophases with uniform pore size (with spacings between 35 and 40 A). The pore arrangement depends on the synthetic conditions and metal used, and include disordered wormhole, hexagonal and even cubic phases. All compounds are medium bandgap semiconductors (varying between 1.4 and 2.5 eV). We expect that such semiconducting porous networks could be used for optoelectronic, photosynthetic and photocatalytic applications.