There is a great need to identify high-performance nanoporous materials for gas storage, separation and catalysis solve wide range of industrially relevant challenges. Molecular simulations have become an important complement experiments in the screening selection suitable porous materials. Successful implementation molecular requires accurate force fields (FFs) describe interactions guest molecules with frameworks. However, developing transferable FFs can be extremely challenging. While...

We demonstrate a new approach to develop transferable force fields describing molecular adsorption in zeolites by combining dispersion-corrected density functional theory (DFT) calculations and classical atomistic simulations. This is illustrated with the of CO2 zeolites. Multiple DFT methods were tested for sodium-exchanged ferrierite. The DFT-D2 was found give best agreement high level quantum chemistry results experimental data. A field siliceous then developed on basis hundreds that...

Defects in the crystal structures of metal–organic frameworks (MOFs), whether present intrinsically or introduced via so-called defect engineering, can play strong roles properties MOFs for various applications. Unfortunately, direct experimental detection and characterization defects are very challenging. We show that many cases, differences between experimentally observed computationally predicted water stabilities be used to deduce information on presence point real materials. Most...

A comprehensive study has been made to probe the spatial proximities among different acid sites in dealuminated H-Y zeolites modified with various degrees of calcination, steam, and treatments by using a variety solid-state NMR techniques, including multinuclear MAS two-dimensional 1H double-quantum (DQ) spectroscopy. The effects dealumination on nature, concentration, location extraframework Al species were followed DQ hydroxyl protons conjunction 1H, 27Al, 29Si results. It was found that...

The validity of using 31P NMR adsorbed trimethylphosphine (TMP) as a probe molecule for discerning the types (Brønsted vs Lewis) and strengths acid sites in solid catalysts have been studied by density functional theory (DFT) calculations. Brønsted with varied acidic covering from weak, strong, to superacid, mimicked 8T zeolite cluster models having different Si−H bond lengths hence proton affinities, were examined together Lewis systems metallic centers, e.g., BClnF3−n (n = 0−3), AlClnF3−n...

Extra-framework aluminium (EFAL) species in hydrated dealuminated HY zeolite were thoroughly investigated by various two-dimensional solid-state NMR techniques as well density functional theoretical calculations. (27)Al MQ MAS experiments demonstrated that five-coordinated and four-coordinated extra-framework subsequently disappeared with the increase of water loading, quadrupole interaction each decreased gradually during hydration process. (1)H double quantum revealed EFAL consisted three...

Twenty carbenium ions in various zeolite models (8T HZSM-5, 72T 84T HY, and 80T Hβ) are investigated by theoretical calculation methods order to reveal the effects of framework on stability ion intermediates. Most found be stable these exist form an pair with conjugate bases. The can also transformed into π complexes and, some cases, alkoxy species if steric constraint around C−O bond is not pronounced. It that inclusion facilitates formation pairs concurrently increase relative compared no...

The development of accurate force fields is vital for predicting adsorption in porous materials. Previously, we introduced a first principles-based transferable field CO2 siliceous zeolites (Fang et al., J. Phys. Chem. C, 2012, 116, 10692). In this study, extend our approach to cationic which possess more complex structures. Na-exchanged are chosen demonstrating the approach. These methods account several structural complexities including Al distribution, cation positions and mobility, all...

Adsorption of basic probe molecules is one the widely used methods to characterize acid strength solid acids. In this contribution, adsorptions acetone on various Brønsted and Lewis sites (from weak superacid) are theoretically studied, in order elucidate quantitative relationships between 13C chemical shifts intrinsic The represented by a series 8T zeolite models with varying terminal Si−H bond lengths, different extents acidic proton transfer from these revealed explicitly. We found that...

Solid porous materials such as cationic zeolites have shown great potential in energy-efficient separation processes. Conventional adsorbent design involves ad-hoc and inefficient experimental evaluation of a large structural compositional space. We developed computational methodology to screen for CO2 processes with quantitative accuracy, identified number novel high-performing materials. This study enabled us develop an intuitive workflow selecting optimal dramatically accelerate the...

Heat of adsorption is an important factor in determining the utility a porous material for gas separation and storage applications. Although theoretically heat can depend on temperature, it common practice to assume that this dependence so weak be ignored. In paper, we challenge wisdom. We simulated isotherms heats small molecules (CO2, CH4, N2) reference siliceous (LTA, CHA, MFI) cation-exchanged (LTA-4A, Na-LTA Si/Al = 2,5) zeolites found very significant temperature isosteric CO2 at low...

The protonation reactions of propene, isobutene, styrene, and α-methylstyrene on 8T solid acid models with varying strengths are theoretically studied in order to reveal the effects strength acid-catalyzed reactions. It is shown that increase (evaluated by deprotonation energy) ion pair intermediates preferentially formed, their stabilities relative π complex alkoxy species considerably increased. Some for bulkier olefinic hydrocarbons (i.e., α-methylstyrene) cannot exist as stable strong...

Most previous studies on development of force fields for molecules in porous materials focus prediction adsorption properties. However, accurately reproducing data is not sufficient to guarantee the accuracy other properties, such as diffusivities. We demonstrate an approach develop based periodic first-principles calculations that can predict both and diffusion properties crystalline nanoporous using CH4 siliceous zeolites example. First, multiple dispersion-corrected density functional...

The sorption of H2S on a silica-supported sterically hindered secondary amine and supported unhindered tertiary is investigated using fixed bed breakthrough experiments. In situ Fourier transform infrared spectroscopy computational analysis are used to elucidate the structure surface species formed during humid sorption. Additionally, cyclic stability amine-functionalized silica sorbent assessed NMR spectroscopy, N2 physisorption, elemental analysis. For all sorbents under dry conditions,...

Zeolites can be partially hydrolyzed by steam via Al extraction which leads to the formation of a moiety with four hydroxyl groups. This irreversible dealumination process decrease crystallinity zeolites and effectively modify their acidity, porosity, catalytic activity. paper addresses hydrolysis mechanism first Al–O bond in protonic (H+) cationic (M = Na+, K+, Ca2+) LTA zeolites. Periodic density functional theory calculations demonstrate that are more kinetically stable than H-LTA...

A recent international interlaboratory study led by the U.S. National Institute of Standards (NIST) reported CO2 adsorption isotherms measured independently 11 groups on reference material RM 8852, an ammonium ZSM-5 zeolite. Good reproducibility and high reliability this experimental data provide a strong test for ability atomically detailed models to predict in zeolites. We developed force fields zeolites based first-principles calculations also performed experiments with 8852...

Adsorption of mercury species in porous materials is an attractive means to capture these from flue gas, but the lack reliable force fields (FFs) for Hg0 and HgCl2 has made modeling adsorption important challenging. We introduce a robust set FFs describe interactions between Hg0, HgCl2, other gas components UiO-66, prototypical metal–organic framework. Using FFs, isotherms UiO-66 pure mixtures N2, CO2, SO2 were simulated. strong affinity with heat ∼60 kJ/mol, whereas only weakly adsorbed....

Excessive absorption of osteoclasts will break the balance between and osteoblasts, leading to bone loss, decreased density, increased fragility. We have shown that Loureirin B (LrB) can inhibit osteoclasts. In this study, we demonstrated targeting-inhibitory mechanism LrB acting on osteoclast precursor. Using SPR, HPLC MALDI-TOF-MS capture analyze target protein in marrow macrophages (BMMs), used method detect all proteins acts BMMs, analyzed distribution enrichment rate by DAVID analysis....

Treatment of steroid-induced osteonecrosis the femoral head (SIONFH) is challenging. Due to limited understanding its molecular mechanisms, investigating potential mechanisms ferroptosis will shed light on SIONFH and provide directions for treating this disease.The GSE123568 dataset was utilized apply various bioinformatics methodologies identify ferroptosis-related hub genes (FRHGs). Subsequently, importance these reliability results were confirmed using protein data-independent acquisition...

Most zeolite membranes contain an active layer of intergrown crystals that are hundreds nanometers to a few microns thick. For such membranes, the effect surface resistances on transmembrane transport is expected be small. Progress has been made in recent years synthesizing nanosheets with unit cell-level thicknesses and converting them into ultrathin zeolitic or catalysts very small intraparticle diffusion length scales. In situations, effects from resistance likely amplified relative large...

We present a transferable force field for hydrocarbons (linear and branched olefins paraffins) small adsorbates (CO2, O2, N2, H2O) in pure silica zeolites. The fitting procedure is based on adsorbate–adsorbent interaction energies obtained from periodic density functional theory calculations corrected using coupled-cluster methods applied to clusters. approach aims at accurate prediction of both adsorption diffusion properties by sets configurations that sample sites intracrystalline hopping...

The majority of molecular simulations adsorption in crystalline nanoporous materials such as zeolites and metal–organic frameworks (MOFs) are performed using a rigid framework. This assumption is made for convenience, with flexible require dedicated force fields more computational power. Several recent studies have hinted that computed properties may, many cases, be quite sensitive to the inclusion framework flexibility associated thermal vibration atoms. It unclear whether this conclusion...