Langmuir最新文献

Metal-organic frameworks (MOFs) are promising materials for CO₂ capture with the potential to use less energy than current industrial CO₂ capture methods. MOFs are highly versatile sorbents, and there is an almost unlimited number of MOFs that could be synthesized. In this work, we used a genetic algorithm (GA) and grand canonical Monte Carlo (GCMC) simulations to efficiently search for high-performing MOFs for CO₂ capture. We analyzed the effects of important GA parameters, including the mutation probability, the number of MOFs per generation, and the number of GA generations, on the GA performance. We performed GCMC simulations on-the-fly during the GA procedure to determine the performance of proposed MOFs and optimized their structures using multiple objective functions across different topologies. The GA was able to determine top-performing MOFs balancing CO₂ selectivity versus working capacity and reduced the cost of molecular simulations by a factor of 25 versus brute-force screening of an entire database of structures.

Sulfated metal-incorporated MCM-48 mesoporous silicates were synthesized hydrothermally using tetraethyl orthosilicate (TEOS) as the silica precursor and cetyltrimethylammonium bromide (CTAB) as the structure-directing agent. The materials were extensively characterized through techniques, such as powder X-ray diffraction (PXRD), N₂ adsorption-desorption, diffuse reflectance UV-vis spectroscopy (UV-vis DRS), Fourier transform infrared spectroscopy (FT-IR), NH₃-temperature-programmed desorption (NH₃-TPD), thermogravimetric analysis (TGA), scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX), and inductively coupled plasma optical emission spectroscopy (ICP-OES). PXRD confirmed the retention of the well-ordered MCM-48 structure in the modified materials, while UV-vis DRS revealed partial incorporation of metal ions in their preferred tetrahedral coordination within the framework. Mesoporosity was verified through N₂ adsorption-desorption isotherms, and NH₃-TPD results showed enhanced acidity in the sulfated catalysts. Catalytic performance was tested in the esterification of benzyl alcohol with acetic acid under liquid-phase conditions. The optimized reaction parameters, using a 9% (w/w) S-Fe-MCM-48 catalyst, a benzyl alcohol to acetic acid molar ratio of 2:1, a temperature of 60 °C, and a solvent-free system over 6 h, yielded benzyl acetate with 98.9% selectivity as the major product. Reusability tests demonstrated the robustness of the S-Fe-MCM-48 catalyst over five successive cycles, indicating its potential suitability for industrial applications.

We investigate the self-assembly behaviors of the tetracarboxylic acid molecule (H₄IMD), which contains an imidazole moiety, and explore the regulation by pyridine derivatives with varying backbones and the guest molecule coronene (COR). Two H₄IMD molecules are linked through N-H···O hydrogen bonds to form a dimer, which spontaneously self-assembles into a grid structure via O-H···O hydrogen bonds. The addition of linear pyridine derivatives (BP and Bispy) can break some of the O-H···O hydrogen bonds, allowing these pyridine molecules to insert between the dimer columns. In contrast, the tripyridine derivative (TPYB) disrupts the original dimer structures, resulting in a completely altered nanostructure. Moreover, the H₄IMD self-assembled structure can be regulated into a rhombus network by the coadsorption of COR molecules. Combining scanning tunneling microscopy and density functional theory calculations, this study elucidates the diverse structural variations and the underlying mechanisms, which provide new insights into molecular coassembly.