MnOxNanoparticles Supported on a New Mesostructured Silicate with Textural Porosity

Synthesis of Mesoporous γ-Alumina Support for Water Composite Sorbents for Low Temperature Sorption Heat Storage

The efficiency of thermochemical heat storage is crucially determined by the performance of the sorbent used, which includes a high sorption capacity and a low regeneration temperature. The thermochemical salt hydrate– γ-alumina composite sorbents are promising materials for this application but lack systematic study of the influence of γ-alumina structural properties on the final storage performance. In this study, mesoporous γ-Al2O3 supports were prepared by solvothermal and hydrothermal synthesis containing a block copolymer (F-127) surfactant to design thermochemical CaCl2 and LiCl composite water sorbents. Altering the solvent in the synthesis has a significant effect on the structural properties of the γ-Al2O3 mesostructure, which was monitored by powder XRD, nitrogen physisorption, and SEM. Solvothermal synthesis led to a formation of mesoporous γ-Al2O3 with higher specific surface area (213 m2/g) and pore volume (0.542 g/cm3) than hydrothermal synthesis (147 m2/g; 0.414 g/cm3). The highest maximal water sorption capacity (2.87 g/g) and heat storage density (5.17 GJ/m3) was determined for W-46-LiCl containing 15 wt% LiCl for space heating, while the best storage performance in the sense of fast kinetics of sorption, without sorption hysteresis, low desorption temperature, very good cycling stability, and energy storage density of 1.26 GJ/m3 was achieved by W-46-CaCl2.

l-Lysine-assisted fabrication of PdxPt1−x/Ni(OH)2 (0 ≤ x ≤ 1) hybrids with composition-dependent catalytic properties

Pd_xPt_1−x/Ni(OH)₂ hybrids with composition-dependent catalytic properties were produced by a fast and facile self-assembly process with biomolecule l-lysine as the linker.

Active Iron Sites of Disordered Mesoporous Silica Catalyst FeKIL-2 in the Oxidation of Volatile Organic Compounds (VOC)

Iron-functionalized disordered mesoporous silica (FeKIL-2) is a promising, environmentally friendly, cost-effective and highly efficient catalyst for the elimination of volatile organic compounds (VOCs) from polluted air via catalytic oxidation. In this study, we investigated the type of catalytically active iron sites for different iron concentrations in FeKIL-2 catalysts using advanced characterization of the local environment of iron atoms by a combination of X-ray Absorption Spectroscopy Techniques (XANES, EXAFS) and Atomic-Resolution Scanning Transmission Electron Microscopy (AR STEM). We found that the molar ratio Fe/Si ≤ 0.01 leads to the formation of stable, mostly isolated Fe³⁺ sites in the silica matrix, while higher iron content Fe/Si > 0.01 leads to the formation of oligonuclear iron clusters. STEM imaging and EELS techniques confirmed the existence of these clusters. Their size ranges from one to a few nanometers, and they are unevenly distributed throughout the material. The size of the clusters was also found to be similar, regardless of the nominal concentration of iron (Fe/Si = 0.02 and Fe/Si = 0.05). From the results obtained from sample characterization and model catalytic tests, we established that the enhanced activity of FeKIL-2 with the optimal Fe/Si = 0.01 ratio can be attributed to: (1) the optimal concentration of stable isolated Fe³⁺ in the silica support; and (2) accelerated diffusion of the reactants in disordered mesoporous silica (FeKIL-2) when compared to ordered mesoporous silica materials (FeSBA-15, FeMCM-41).

Hazardous dyes removal from aqueous solution over mesoporous aluminophosphate with textural porosity by adsorption

Dye pollution in aquatic nature produce serious environmental effects. In this investigation, mesoporous aluminophosphate molecular sieve synthesized and applied for the removal of hazardous dyes Malachite green (MG) and Methylene blue (MB). In the synthesis of mesoporous aluminophosphate (AlPO(4)) molecular sieve, the structure-directing agent, long-chain alkylbenzene has been used as a template. The template used for the synthesis of mesoporous material is environmentally biodegradable. The mesoporous AlPO(4) was synthesized by the absence of an organic base, tetramethyl ammonium hydroxide (TMAOH) which is necessary to maintain the pH for the conventional AlPO(4) synthesis methods. The synthesized mesoporous AlPO(4) has high thermal stability up to 1173K and large porosity nature (40 nm). It was confirmed by the characterization techniques such as low-angle XRD, FT-IR, TGA and BET surface area analysis. The morphology of the material was explained by using SEM and TEM. The hazardous dyes MG and MB removal studied under the various conditions like contact time, dye concentration, temperature, pH and adsorbent dosage to examine the adsorption characteristics of the newly synthesized mesoporous AlPO(4) molecular sieves.