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In this work, we present the preparation of hybrid materials constituted by a Metal Organic Framework (type CPO-27-Mg) and a mesoporous silica (type KIT-6) which were successfully assembled through an in situ hydrothermal method. The composites were characterised by powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), microscopic techniques (SEM and TEM), N2 adsorption–desorption isotherms at 77 K and CO2 adsorption at 273 K; these techniques confirmed the obtaining of hybrid materials and not simple physical mixtures. Finally, the hybrid materials were tested in the CO2 adsorption at different temperatures and from 0–10 bar of pressure, where the exposure to high relative humidity were also monitored. The CPO-27-Mg@KIT-6 (1 : 1) and (2 : 1) composites exhibited interesting values of CO2 adsorption capacity, compared with those reported in the literature. Therefore, this study opens new pathways for designing porous structured MOF-based materials with advanced gas separation performance. [ABSTRACT FROM AUTHOR]

An adsorbent material arranged in a ceramic monolith (CM) obtained by extrusion technique using natural bentonite and alumina (as raw materials) is presented. Ceramic and raw materials were characterized by X-ray fluorescence, thermal analysis, X-ray diffraction, and textural analysis (with N2 adsorption–desorption at 77 K and Hg intrusion–extrusion porosimetry) to determine their chemical and physical properties. Then, As (V) adsorption capacity of the CM at different pH (3–9) using arsenic aqueous solution (with 2000 µg As (V) L−1) was evaluated. Additionally, studies of kinetics and equilibrium of As (V) adsorption on CM were performed. It was found that: (i) the As (V) removal capacity is favored at acidic pH, reaching an average value of 15 µg As (V) per gram of CM; (ii) from kinetic studies, As (V) adsorption on CM occur in two stages, the first of them reaching a lower As uptake in a short time period, followed by an slow second stage with a subsequent higher As uptake, which continued for a longer time period, reaching equilibrium conditions in approximately 24 h; and (iii) the As (V) adsorption isotherm is a type-Langmuir, indicating that the CM present an homo quantity of fixed sites to adsorb the As (V). [ABSTRACT FROM AUTHOR]

Novel ceramic foams were obtained by the replica method, using bentonite as alternative raw material and polyurethane sponge as template, where the latter also controls the distribution of the pore size of these ceramics. The synthesis of the ceramics was carried out using slurries of bentonite clay with different percentages of sodium carboxymethyl cellulose as a binder, and evaluating different calcination temperatures. The effect of these factors on the textural and morphological properties of the ceramic foams was studied. The porosity measured by mercury intrusion showed that the total porosity of the ceramic foams decreases as the calcination temperature increases. Furthermore, a small quantity of porosity is generated after the burnout of the binder during the calcination step. This porosity is given by pore sizes from 0.05 to 3 µm and it was increased with the amount of the binder that was increased, which was also confirmed by scanning electron micrographs. The characterization of bentonite clay, polyurethane, coated polyurethane sponge and ceramic foams was also complemented with thermogravimetric analysis, nitrogen adsorption at 77 K, and mechanical strength measurements. [ABSTRACT FROM AUTHOR]

The equilibrium adsorption and kinetics of CO 2 on several microporous materials has been studied at 273, 283 and 293 K and gas pressures of up to 100 kPa. The porous materials used in this work were two zeolites (5A and 13X), two metal–organic frameworks (Basolite A100 and Basolite Z1200), an activated carbon and two pillared clays (Al-PILC and Zr-PILC). The isothermal and non-isothermal diffusion models were applied to calculate the diffusion time constants ( D 0 / r c 2 ) from the uptake curves. The non-isothermal model was found to fit the experimental data well over the whole range of adsorption rates. The values found for the zeolites, which ranged from 0.020 to 0.043 s −1 , were lower than those for the metal–organic frameworks and pillared clays, which ranged from 0.036 to 0.081 s −1 , in the same interval of temperatures. Furthermore, the values of the diffusion time constants were found to depend on gas pressure. The pressure-dependence of the diffusion time constants was studied using the Darken equation. Finally, activation energy values were estimated from the temperature-dependence for all materials and it was found to increase in the order: Z1200 < Al-PILC < 13X < AC < Zr-PILC < 5A; A100. [ABSTRACT FROM AUTHOR]

A computational and experimental screening of hypothetical and real compounds exhibiting different degrees of ethylenediamine grafted to the CPO-27-Mg or Mg-DOBDC skeleton is performed in order to determine the target composition that optimizes the CO2 adsorption properties under flue gas and air filtering conditions. On the basis of the [Mg2(dobdc)] formula, eighteen hypothetical models involving 15–100% of functionalization of the coordinatively unsaturated sites (CUS) were considered by means of Grand Canonical Monte Carlo simulations to evaluate the CO2 adsorption at 298 K. In addition, post-synthesis modification was applied to CPO-27-Mg leading to three kinds of samples exhibiting 15, 50, and 60% of CUS functionalization with ethylenediamine, named CPO-27-Mg-a, CPO-27-Mg-b and CPO-27-Mg-c. Compounds were characterized using elemental analysis, TGA, FTIR spectroscopy, PXRD and DSC. Finally, bare and functionalized CPO-27-Mg materials were evaluated using gas adsorption and microcalorimetry in the 0.001–1 bar range, which is pertinent for the mentioned applications. Valuable information related to design criteria for synthesis of tuned CO2 adsorbents is derived through this computational and experimental investigation. [ABSTRACT FROM AUTHOR]

The adsorption ofCO2on several microporous materialshas been measured at various temperatures (263, 273, 283, and 293K) over a wide range of pressures. The porous materials studied werethree zeolites (5A, 13A, and 13X), two metal–organic frameworks(Basolite A100 and Basolite Z1200), an activated carbon, and two pillaredclays (Al-PILC and Zr-PILC). The data obtained were fitted to theFreundlich, Langmuir, and Toth isotherms. Various methods were usedto calculate the Henry’s law constants. The values found forthe zeolites, which ranged from 8.95 to 36.02 mmol/kPa·g at 273K, were much higher than those for the metal–organic frameworks,activated carbon, and pillared clays, which ranged from 0.012 to 0.200mmol/kPa·g at the same temperature. The isosteric heats of adsorptionof CO2on the materials were calculated using the Clausius–Clapeyronequation, and the adsorbent–CO2affinity was foundto increase in the order Z1200 ≈ 13X ≈ 13A < 5A