Highly selective adsorption of p-xylene over other C8 aromatic hydrocarbons by Co-CUK-1: a combined experimental and theoretical assessment.

High quality crystalline Co-CUK-1 can be synthesized rapidly and efficiently by a microwave-assisted method. The resulting microporous coordination material is a highly effective adsorbent for the separation of xylene isomers and ethylbenzene, as demonstrated here through sorption isotherm analysis, Ideal Adsorbed Solution Theory (IAST) calculations, and grand canonical Monte Carlo (GCMC) simulations. Co-CUK-1 showed high sorption capacity and high adsorption selectivity for p-xylene over the corresponding m- and o-isomers, and ethylbenzenes. According to the data obtained from IAST and GCMC simulations, the Co-CUK-1 is found to strongly favour p-xylene adsorption because p-xylene molecules undergo well-defined molecular packing in the 1-D channels; by comparison, the packing efficiencies of o-xylene, m-xylene and ethylbenzene are significantly lower, as is evidenced by lower saturation capacities.

Synthesis and charge storage properties of templated LaMnO3-SiO2 composite materials.

Mesoporous LaMnO3 with bulk surface areas in the range 225-300 m2 g-1 were prepared by direct overgrowth around the short-channel version of SBA-15 silica. The extent of LaMnO3 growth was found to be affected by the polarity of solvent system used to impregnate the SBA-15 with La3+ and Mn2+ precursors. The resulting LaMnO3-SiO2 composites were stable in refluxing NaOH, suggesting that the SiO2 was fully encapsulated. The composites were structurally characterized using a range of techniques including 2-D elemental mapping and Raman spectroscopy. The electrochemical behavior of the composites was tested for pseudocapacitance, which revealed normalized specific capacitances over 200 F g-1.

Microwave synthesis of classically immiscible rhodium-silver and rhodium-gold alloy nanoparticles: highly active hydrogenation catalysts.

Noble metal alloys are important in large-scale catalytic processes. Alloying facilitates fine-tuning of catalytic properties via synergistic interactions between metals. It also allows for dilution of scarce and expensive metals using comparatively earth-abundant metals. RhAg and RhAu are classically considered to be immiscible metals. We show here that stable RhM (M = Ag, Au) nanoparticles with randomly alloyed structures and broadly tunable Rh:M ratios can be prepared using a microwave-assisted method. The alloyed nanostructures with optimized Rh:M compositions are significantly more active as hydrogenation catalysts than Rh itself: Rh is more dilute and more reactive when alloyed with Ag or Au, even though the latter are both catalytically inactive for hydrogenation. Theoretical modeling predicts that the observed catalytic enhancement is due to few-atom surface ensemble effects in which the overall reaction energy profile for alkene hydrogenation is optimized due to Rh-M d-band intermixing.