CO2/CH4 Separation by Adsorption using Nanoporous Metal organic Framework Copper‐Benzene‐1,3,5‐tricarboxylate Tablet

Equilibrium data for carbon dioxide and methane adsorption on nanoporous metal organic framework Cu‐BTC powder and tablets were measured in a magnetic suspension balance in the temperature range of 308–373 K and a pressure range of 0–7 bar and fitted with Langmuir model. The tablets adsorption loading is 0.63 mol kg^–1 for methane and 3.1 mol kg^–1 for carbon dioxide at 1 bar and 308 K, while these values are 0.77 and 3.9 mol kg^–1 for powder in the same conditions. Isosteric heats of adsorption were 22.8 and 15.0 kJ mol^–1 for carbon dioxide and methane, respectively, on both adsorbents, which indicates a strong adsorption of carbon dioxide. Also, single and binary breakthrough curves were measured in the same temperature range and atmospheric pressure by using Cu‐BTC tablets as adsorbent. A complete model was used in the simulation of breakthrough curves and good agreement was observed with experimental data.     

Advanced Monte Carlo simulations of the adsorption of chiral alcohols in a homochiral metal‐organic framework

Grand canonical Monte Carlo (GCMC) simulations with configurational biasing were used to study the enantioselective adsorption of four alkanols in a homochiral metal‐organic framework, known as hybrid organic‐inorganic zeolite analogue HOIZA‐1. Conventional GCMC simulations are not able to converge satisfactorily for this system due to the tight fit of the chiral alcohols in the narrow pores. However, parallel tempering and parallel mole‐fraction GCMC simulations overcome this problem. The simulations show that the enantioselective adsorption of the different (R,S)‐alkanols is due to the specific geometry of the chiral molecules relative to the pore size and shape. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2324–2334, 2014     

Efficient Removal of Anionic Organic Dyes from Aqueous Solution with Cu‐Organic Frameworks

Cu‐metal‐organic frameworks (Cu‐MOFs) were synthesized in one step using copper acetate, glutamic acid, and small‐molecular organic amines at room temperature. Organic amines served as modulators to modify the structure of Cu‐MOFs. Characterization results proved that the addition of modulators changes the surface morphology. Batch adsorption data indicated high adsorption capacities for anionic organic dyes with glutamic‐Cu‐triethylamine (Glu‐Cu‐TA), higher than that of most MOFs reported. An acid pH was the optimum adsorption parameter. The easy regeneration of recycled Cu‐MOFs suggested there were weak intermolecular interactions between Cu‐MOFs and dyes. The main adsorption forces included electrostatic interaction, ion exchange, π‐π complexation, and hydrogen bonds.     

A Computational Study of the Adsorptive Removal of H<Subscript>2</Subscript>S by MOF-199

Metal–organic framework material MOF-199 is a new type of adsorption material for removal toxic H₂S. In this work, the effects of temperature and pressure on the performance of H₂S adsorption in MOF-199 were studied by using the grand canonical Monte Carlo (GCMC) simulation; the interaction mechanism between framework atoms of MOF-199 and guest H₂S molecules were further discussed through density functional theory (DFT) calculations. It is found that the MOF-199 adsorption capacity towards H₂S decreases with increasing temperature and increases with increasing pressure. At low pressures, the frameworks containing the binding sites of copper dimers and trimesic acid are the main factor affecting the adsorption performance of MOF-199. While at high pressures, the free volume of MOF-199 contributes to the adsorption capacity as well. The adsorptive interactions between H₂S and the organic ligand are weak (>??14.469 kJ/mol). When H₂S adsorption on the Cu–Cu bridge, the binding energies of the modes where hydrogen is put inward of the copper dimer are generally smaller than that where hydrogen is outward, whereas the adsorption on the top of copper ion shows the smallest BEs value (<??50 kJ/mol) due to its tendency of forming a saturated six-coordinated configuration.     

Bifunctional Metal Organic Framework Catalysts for Multistep Reactions: MOF‐Cu(BTC)‐[Pd] Catalyst for One‐Pot Heteroannulation of Acetylenic Compounds

A bifunctional metal organic framework catalyst containing palladium and copper(II) benzene‐1,3,5‐tricarboxylate – MOF‐Cu(BTC)‐[Pd] – has been prepared. This catalyst enables the performance of the tandem Sonogashira/click reaction starting from 2‐iodobenzylbromide, sodium azide and alkynes to produce 8H‐[1,2,3]triazolo[5,1‐a]isoindoles with good yields under mild reaction conditions.     

Water adsorption in metal–organic frameworks with open‐metal sites

H₂O adsorptions inside porous materials, including silica zeolites, zeolite imidazolate frameworks, and metal–organic frameworks (MOFs) using molecular simulations with different water models are investigated. Due to the existence of coordinately unsaturated metal sites, the predicted adsorption properties in M‐MOF‐74 (M = Mg, Ni, Co, Zn) and Cu‐BTC are found to be greatly sensitive to the adopted H₂O models. Surprisingly, the analysis of the orientations of H₂O minimum energy configuration in these materials show that three‐site H₂O models predict an unusual perpendicular angle of H₂O plane with respect to the Metal‐O₄ plane, whereas those models with more than three sites give a more parallel angle that is in better agreement with the one obtained from density functional theory (DFT) calculations. In addition, the use of these commonly used models estimates the binding energies with the values lower than the ones computed by DFT ranging from 15 to 40%. To correct adsorption energies, simple approach to adjust metal‐O(H₂O) sigma parameters to reproduce the DFT‐calculated binding energies is used. With the refined parameters, the computed water isotherms inside Mg‐MOF‐74 and Cu‐BTC are in reasonable agreement with experimental data, and provide significant improvement compared to the predictions made by the original models. Further, a detailed inspection on the water configurations at higher‐pressure region was also made, and observed that there is an interesting two‐layer water network formed using three‐ and four‐site models. © 2014 American Institute of Chemical Engineers AIChE J, 61: 677–687, 2015     

Materials genomics‐guided ab initio screening of MOFs with open copper sites for acetylene storage

Discovering high‐performance metal‐organic frameworks (MOFs) with open metal sites has become an increasingly hot research topic in the field of safe storage and transportation of acetylene. Following the concept of Materials Genomics proposed recently, a database of 502 experimental MOFs was built by searching the structures deposited in the CSD with the dicopper paddle‐wheel node Cu₂(COO)₄ as the characteristic materials gene. On the basis of the developed ab initio force field, a high‐throughput computational screening was conducted to examine the property‐performance relationships of MOFs containing Cu‐OMS for C₂H₂ storage at ambient conditions. The optimal ranges of the structural and energetic features for the design of such MOFs were suggested. From our computational screening, three potentially promising MOFs were identified which exhibit a performance outperforming those MOFs reported experimentally so far with record high gravimetric C₂H₂ uptakes, both in the total and deliverable adsorption capacities. © 2017 American Institute of Chemical Engineers AIChE J, 64: 1389–1398, 2018     

A novel carbonized polydopamine (C‐PDA) adsorbent with high CO2 adsorption capacity and water vapor resistance

Novel carbonized polydopamine adsorbents (C‐PDAs) with high surface area, high CO₂ adsorption capacity and superior moisture resistance performance were prepared by one‐step synthesis method using polydopamine as carbon precursor at different KOH/C ratios, and then characterized. CO₂ and water vapor adsorption performances of C‐PDAs were examined separately by static adsorption and fixed‐bed experiments. Results showed that BET area and pore volume of C‐PDA‐4 were up to 3342 m²/g and 2.01 cm³/g, respectively. Its CO₂ adsorption capacity reached up to 30.5 mmol/g at 25 bar, much higher than many other adsorbents including metal‐organic frameworks (MOFs). C‐PDAs prepared with high KOH/C ratios had low surface element concentrations of O and N resulting in low surface hydrophilic property. H₂O(g) isotherm of C‐PDA was much lower than those on Mg‐MOF‐74, Cu‐BTC, and MIL‐101(Cr). Fixed‐bed experiments showed that co‐presence of water vapor in feed stream with 30% RH had negligible impact on CO₂ working capacity of C‐PDA. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3730–3738, 2016     

The Low‐Temperature High‐Pressure Phase Diagram of Energetic Materials: I. Hexahydro‐1,3,5‐Trinitro‐s‐Triazine

The reaction phase diagram of hexahydro‐1,3,5‐trinitro‐s‐triazine (RDX) has been studied as a function of temperature and pressure by Raman spectroscopy to 29 GPa and temperatures ranging from 4 to 298 K. Three stable phases (α, γ, and δ) have been found and their phase stabilities have been investigated. Phase boundaries were studied as a function of pressure and temperature, permitting a delineation of the various polymorph stability fields. A pressure–temperature reaction/phase diagram is constructed from the results of this study and compared to previous high temperature work.     

Screening CO2/N2 selectivity in metal‐organic frameworks using Monte Carlo simulations and ideal adsorbed solution theory

Selective adsorption of CO₂ over N₂ is important in the design and selection of adsorbents such as metal‐organic frameworks (MOFs) for CO₂ capture and sequestration. In this work, single‐component and mixture adsorption isotherms were calculated in MOFs using grand canonical Monte Carlo (GCMC) simulations at conditions relevant for CO₂ capture from flue gas. Mixture results predicted from single‐component isotherms plus ideal adsorbed solution theory (IAST) agree well with those calculated from full GCMC mixture simulations. This suggests that IAST can be used for preliminary screening of MOFs for CO₂ capture as an alternative to more time‐consuming mixture simulations or experiments. © 2011 Canadian Society for Chemical Engineering     

Antibacterial activity against Escherichia coli of Cu‐BTC (MOF‐199) metal‐organic framework immobilized onto cellulosic fibers

A strong antimicrobial activity against Escherichia coli of Cu‐BTC metal‐organic frameworks immobilized over cellulosic fibers is hereby reported. The in situ synthesis of Cu‐BTC metal‐organic frameworks, aka MOF‐199 or HKUST‐1, onto cellulosic substrates was carried out by exposing carboxymethylated cellulosic substrates to Cu(OAC)₂, 1,3,5‐benzenetricarboxylic acid and triethylamine solutions following a very specific order. Using an in vitro model, in accordance to ASTM E2149‐13a, we observed that the cellulose‐MOF system was able to completely eliminate the growth of E. coli on agar plates and liquid cultures. The antibacterial activity of the comprising components of MOF‐199 and the cellulosic substrate was also evaluated and determined to be negligible. Since the method used to synthesize MOF‐199 crystals provides a strong bond between the crystals and the cellulosic substrates, the crystals not detach from the anionic cellulosic fibers allowing the modified textile to be washed and reused hence opening a new avenue to fabricate antibacterial clinical fabrics. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40815.     

Adsorption of Cu2+ ions with poly(N‐isopropylacrylamide‐co‐methacrylic acid) micro/nanoparticles

Chelation efficiency of stimuli‐responsive poly(N‐iospropylacrylamide‐co‐methyacrylic acid) (PNIPAAm‐MAA) nanoparticles with Cu²⁺ ions from CuSO₄·5H₂O solution and from wood treated with copper‐based preservatives was studied. It was shown that particle size played a very important role in the adsorption process. The nano‐scale particles showed much improved Cu ion adsorption efficiency, compared with the micro hydrogels. The amount of Cu ion adsorption increased with increase of MAA ratio in copolymers and adsorption efficiency decreased with increased particle size. Furthermore, the adsorption amount varied with adsorption temperature at temperatures both below and above the corresponding low critical solution temperature (LCST). The high adsorption efficiency of Cu ions by PNIPAAm‐MAA polymer particles provides an effective technique for recovering metal ions (e.g., Cu²⁺) from wood treated with metal‐based preservatives. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Modeling of Water Adsorption in SAPO‐34‐Coated Aluminum Foam

After presenting the most promising continuous adsorption cooling topology for air‐conditioning of a passenger cabin, a transient, 3D model is proposed, based on a modified linear driving force approach, to simulate an adsorption process in a SAPO‐34‐coated open‐celled aluminum foam. The simulation is executed in ANSYS CFX 15.0 and the additional model equations are implemented through the CFX expression language. As a result the influence of the pore diameter onto the system simulation and the mass transport limitation is shown and the sensitivity concerning the pressure in the gas phase adsorption is confirmed.     

Architecture and performance of mesoporous silica‐lipase hybrids via non‐covalent interfacial adsorption

To investigate the effects of surface property of mesoporous supports on the lipase immobilization and the performance of immobilized lipase, the mesoporous molecular sieve SBA‐15 is functionalized with three organic moieties, dimethyl (DM), diisopropyl (DIP), and diisobutyl (DIB), respectively, by post‐synthesis grafting and one‐pot synthesis methods. Porcine pancreas lipase (PPL) is immobilized on SBA‐15 supports through hydrogen bonding and hydrophobic interaction. The hydrophobic adsorption involves no active sites of PPL, and neither hyper‐activation nor total inactivation occurs. The study on the intrinsic stability of PPL, including thermal stability, pH stability, and storage stability, indicates that the entrapment in mesoporous supports, and especially in organic‐functionalized supports, makes PPL more resistant to temperature increment but more sensitive to pH change. The reusability investigation shows that the organic modification of mesoporous surface inhibits the enzyme leaching to some extent, resulting in a better operational stability. © 2009 American Institute of Chemical Engineers AIChE J, 2010     

Preparation of Magnesium‐based Hydrogen Storage Materials and Their Effect on the Thermal Decomposition of Ammonium Perchlorate

Magnesium‐based hydrogen storage materials (MgH₂, Mg₂NiH₄, and Mg₂Cu‐H) were prepared and their structures were determined by XRD and ICP investigations. Mg₂NiH₄ has a monoclinic crystal structure and Mg₂Cu‐H is a mixture of MgCu₂ and MgH₂. The effects of magnesium‐based hydrogen storage materials on the thermal decomposition of ammonium perchlorate (AP) were studied by thermal analysis (DSC). It was found that magnesium‐based hydrogen storage materials show obvious boosting effects on the thermal decomposition of AP. The thermal decomposition peak temperature of AP was decreased, while the heat release of the decomposition of AP was increased. It was revealed that the effects of magnesium‐based hydrogen storage materials on the decomposition of AP become stronger with increasing content. The influence mechanism on the thermal decomposition of AP is suggested as follows: hydrogen released from magnesium‐based hydrogen storage materials and Mg, Ni, or Cu react with the decomposed products of AP.     

Full‐Loop Simulation of Gas‐Solids Flow in a Pilot‐Scale Circulating Fluidized Bed

In order to study the system hydrodynamics in a circulating fluidized bed (CFB), a 3D full‐loop simulation was conducted for a pilot‐scale CFB. The Eulerian‐Eulerian two‐fluid model with the kinetic theory of granular theory helped to simulate the gas‐solids flow in the CFB. The system hydrodynamics including pressure balance, vectors of gas and solids, distribution of solids holdup, and instantaneous circulating rates were obtained to get a comprehensive understanding of the system. It was predicted that the main driving force was the pressure drop of the storage tank. The storage height and valve opening were critical operating factors to control the riser operation. The effects of operating conditions including solids circulating rates and superficial gas velocity on the hydrodynamics were investigated to provide guidance for the stable operation of the CFB system.     

High‐throughput and comprehensive prediction of H2 adsorption in metal‐organic frameworks under various conditions

High‐throughput prediction of H₂ adsorption in metal‐organic framework (MOF) materials has been extended from a few specific conditions to the whole T, p space. The prediction is based on a classical density functional theory and has been implemented over 712 MOFs in 441 different conditions covering a wide range. Some testing materials show excellent behavior at low temperatures and obvious improvement at high temperatures compared to conventional MOFs. The structures of the best MOFs at high and low temperatures are totally different. Linear and nonlinear correlations between the two Langmuir parameters have been found at high and low temperatures, respectively. According to the analysis of the excess uptake, we found that the saturated pressure increases along with temperature in the low temperature region but decreases in the high temperature region. © 2015 American Institute of Chemical Engineers AIChE J, 61: 2951–2957, 2015     

Hydrogen adsorption and storage on porous materials

The development of safe and efficient methods of hydrogen storage is a prerequisite for the use of hydrogen with fuel cells for transport applications. In this paper, results available for adsorption of hydrogen on porous materials, ranging from activated carbons to metal organic framework materials, are discussed. The results indicate that up to 5 and 7.5 wt% of hydrogen can be stored on porous carbon and metal organic framework materials, respectively, at 77 K. The amounts of hydrogen adsorbed on porous materials at ambient temperatures and high pressures are much lower (0.5 wt%). The strong temperature dependence of hydrogen physisorption on porous materials is a limitation in the application of this method for hydrogen storage in addition to storage capacity requirements.     

Vapor–liquid equilibria of hydrogen chloride,phosgene, benzene,chlorobenzene, ortho‐dichlorobenzene,and toluene by molecular simulation

Vapor–liquid equilibria (VLE) of nine binary mixtures containing hydrogen chloride or phosgene in the solvents benzene, chlorobenzene, ortho‐dichlorobenzene, and toluene as well as the mixture hydrogen chloride + phosgene are predicted by molecular modeling and simulation. The underlying force fields for the pure substances are developed on the basis of quantum chemical information on molecular geometry and electrostatics. These are individually optimized to experimental pure fluid data on the vapor pressure and saturated liquid density, where the deviations are typically less than 5 and 0.5 %, respectively. The unlike dispersive interaction is optimized for seven of the nine studied binaries. Previously unpublished experimental binary VLE data, measured by BASF in the vicinity of ambient temperature, are predominantly used for these fits. VLE data, including dew point composition, saturated densities and enthalpy of vaporization, are predicted for a wide range of temperatures and compositions. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Adsorption of heavy‐metal ions on poly(ethylene imine)‐immobilized poly(methyl methacrylate) microspheres

Poly(methyl methacrylate) (PMMA) microspheres carrying poly(ethylene imine) (PEI) were prepared for the removal of heavy‐metal ions (copper, cadmium, and lead) from aqueous solutions with different amounts of these ions (50–600 mg/L) and different pH values (3.0–7.0). Ester groups in the PMMA structures were converted to imine groups in a reaction with PEI as a metal‐chelating ligand in the presence of NaH. The adsorption of heavy‐metal ions on the unmodified PMMA microspheres was very low [3.6 μmol/g for Cu(II), 4.6 μmol/g for Cd(II), and 4.2 μmol/g for Pb(II)]. PEI immobilization significantly increased the heavy‐metal adsorption [0.224 mmol/g for Cu(II), 0.276 mmol/g for Cd(II), and 0.126 mmol/g for Pb(II)]. The affinity order of adsorption (in moles) was Cd(II) > Cu(II) > Pb(II). The adsorption of heavy‐metal ions increased with increasing pH and reached a plateau value around pH 5.5. Their adsorption behavior was approximately described with the Langmuir equation. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 197–205, 2001