RESUMO
The metal-organic framework (MOF)-type MFM-300(Sc) exhibits a combined physisorption and chemisorption capture of H2S, leading to a high uptake (16.55 mmol g-1) associated with high structural stability. The irreversible chemisorbed sulfur species were identified as low-order polysulfide (n = 2) species. The isostructural MFM-300(In) was demonstrated to promote the formation of different polysulfide species, paving the way toward a new methodology to incorporate polysulfides within MOFs for the generation of novel MOF-lithium/sulfur batteries.
RESUMO
The structure transformation of Mg-CUK-1 due to the confinement of H2O molecules was investigated. Powder X-ray diffraction (PXRD) patterns were collected at different H2O loadings and the cell parameters of the H2O-loaded Mg-CUK-1 material were determined by the Le Bail strategy refinements. A bottleneck effect was observed when one hydrogen-bonded H2O molecule per unit cell (18% relative humidity (RH)) was confined within Mg-CUK-1, confirming the increase in the CO2 capture for Mg-CUK-1.
RESUMO
The enhancement of CO2 capture due to the confinement of polar molecules within InOF-1 was previously demonstrated. In particular, the presence of MeOH produced 1.30-fold increase in the total CO2 capture. This was explained before with the presence of hydrogen bonds. However, a detailed analysis of the hydrogen bonds among µ2-OH functional groups, MeOH molecules and CO2 molecules was not elucidated; moreover, the possible mechanisms that could explain the enhancement of the capture were also not explained. In this investigation, the density functional theory (DFT) periodic calculations and experimental in situ DRIFTS results allowed us to postulate four plausible CO2 adsorption mechanisms for MeOH-functionalised InOF-1, which described the hydrogen bonds and rationalised the nature of the CO2 capture enhancement.
RESUMO
A greener synthesis of Cu-MOF-74 was obtained, for the first time, in methanol as the unique solvent and at room temperature. Full characterisation of the MOF material showed its purity and also its nanocrystalline nature. Complete activation (150 °C for 1 h and 10-3 bar) of Cu-MOF-74 afforded unsaturated Cu metal sites and this was corroborated by in situ DRIFT spectroscopy. The access to these Cu open metal sites was tested for the catalytic transformation of trans-ferulic acid to vanillin (yield of 71% and 97% selectivity) and a plausible catalytic reaction mechanism was postulated based on quantum chemical calculations.
RESUMO
Benzene alkylation with propylene was studied in the gas phase using a catalytic membrane reactor and a fixed-bed reactor in the temperature range of 200-300 °C and with a weight hourly space velocity (WHSV) of 51 h-1. ß-zeolite was prepared by hydrothermal synthesis using silica, aluminum metal and TEAOH as precursors. The membrane's XRD patterns showed good crystallinity for the ß-zeolite film, while scanning electron microscopy SEM results indicated that its random polycrystalline film was approximately 1 µm thick. The powders' specific area was determined to be 400 m²×g-1 by N2 adsorption/desorption, and the TPD results indicated an overall acidity of 3.4 mmol NH3×g-1. Relative to the powdered catalyst, the catalytic membrane showed good activity and product selectivity for cumene.