Timothy I. Morrow

Bio: Timothy I. Morrow is an academic researcher from University of Notre Dame. The author has contributed to research in topics: Ionic liquid & Hexafluorophosphate. The author has an hindex of 6, co-authored 7 publications receiving 1965 citations.

Why Is CO2 so soluble in imidazolium-based ionic liquids?

Abstract: Experimental and molecular modeling studies are conducted to investigate the underlying mechanisms for the high solubility of CO2 in imidazolium-based ionic liquids. CO2 absorption isotherms at 10, 25, and 50 °C are reported for six different ionic liquids formed by pairing three different anions with two cations that differ only in the nature of the “acidic” site at the 2-position on the imidazolium ring. Molecular dynamics simulations of these two cations paired with hexafluorophosphate in the pure state and mixed with CO2 are also described. Both the experimental and the simulation results indicate that the anion has the greatest impact on the solubility of CO2. Experimentally, it is found that the bis(trifluoromethylsulfonyl)imide anion has the greatest affinity for CO2, while there is little difference in CO2 solubility between ionic liquids having the tetrafluoroborate or hexafluorophosphate anion. The simulations show strong organization of CO2 about hexafluorophosphate anions, but only small diffe...

Molecular Dynamics Study of the Ionic Liquid 1-n-Butyl-3-methylimidazolium Hexafluorophosphate

Abstract: We report the results of a molecular dynamics study of the ionic liquid 1-n-butyl-3-methylimidazolium hexafluorophosphate [bmim][PF6], a widely studied ionic liquid. An all-atom force field is developed using a combination of density functional theory calculations and CHARMM 22 parameter values. Molecular dynamics simulations are carried out in the isothermal−isobaric ensemble at three different temperatures. Quantities computed include infrared frequencies, molar volumes, volume expansivities, isothermal compressibililties, self-diffusivities, cation−anion exchange rates, rotational dynamics, and radial distribution functions. Computed thermodynamic properties are in good agreement with available experimental values.

Isomolar semigrand ensemble molecular dynamics: Development and application to liquid-liquid equilibria

Abstract: An extended system molecular dynamics method for the isomolar semigrand ensemble (fixed number of particles, pressure, temperature, and fugacity fraction) is developed and applied to the calculation of liquid-liquid equilibria (LLE) for two Lennard-Jones mixtures. The method utilizes an extended system variable to dynamically control the fugacity fraction ξ of the mixture by gradually transforming the identity of particles in the system. Two approaches are used to compute coexistence points. The first approach uses multiple-histogram reweighting techniques to determine the coexistence ξ and compositions of each phase at temperatures near the upper critical solution temperature. The second approach, useful for cases in which there is no critical solution temperature, is based on principles of small system thermodynamics. In this case a coexistence point is found by running N-P-T-ξ simulations at a common temperature and pressure and varying the fugacity fraction to map out the difference in chemical potent...

Isomolar-semigrand ensemble molecular dynamics: application to vapor-liquid equilibrium of the mixture methane/ethane.

Abstract: The isomolar-semigrand ensemble molecular dynamics (iSGMD) method is applied to the simulation of the binary system methane/ethane. The vapor-liquid equilibrium properties of this system at a temperature of 192.37K are computed using the Gibbs-Duhem integration method. The iSGMD method, which resembles conventional hybrid Monte Carlo (MC) but is applicable to phase equilibrium calculations, is designed to overcome the difficulties associated with performing standard Monte Carlo-type particle transformations in liquid systems that are very dense and/or are comprised of complex molecules with many intramolecular degrees of freedom. This work shows that particle transformations using the iSGMD method for the simple system methane/ethane are at least 25 times more successful than standard MC-type transformations. The P-x-y curve for the system methane/ethane at 192.37K computed using iSGMD simulations agrees very well with the experimental P-x-y curve as well as results of a previous MC study.

Carbon Dioxide Capture: Prospects for New Materials

Abstract: The escalating level of atmospheric carbon dioxide is one of the most pressing environmental concerns of our age. Carbon capture and storage (CCS) from large point sources such as power plants is one option for reducing anthropogenic CO(2) emissions; however, currently the capture alone will increase the energy requirements of a plant by 25-40%. This Review highlights the challenges for capture technologies which have the greatest likelihood of reducing CO(2) emissions to the atmosphere, namely postcombustion (predominantly CO(2)/N(2) separation), precombustion (CO(2)/H(2)) capture, and natural gas sweetening (CO(2)/CH(4)). The key factor which underlies significant advancements lies in improved materials that perform the separations. In this regard, the most recent developments and emerging concepts in CO(2) separations by solvent absorption, chemical and physical adsorption, and membranes, amongst others, will be discussed, with particular attention on progress in the burgeoning field of metal-organic frameworks.

Carbon capture and storage update

Abstract: In recent years, Carbon Capture and Storage (Sequestration) (CCS) has been proposed as a potential method to allow the continued use of fossil-fuelled power stations whilst preventing emissions of CO2 from reaching the atmosphere. Gas, coal (and biomass)-fired power stations can respond to changes in demand more readily than many other sources of electricity production, hence the importance of retaining them as an option in the energy mix. Here, we review the leading CO2 capture technologies, available in the short and long term, and their technological maturity, before discussing CO2 transport and storage. Current pilot plants and demonstrations are highlighted, as is the importance of optimising the CCS system as a whole. Other topics briefly discussed include the viability of both the capture of CO2 from the air and CO2 reutilisation as climate change mitigation strategies. Finally, we discuss the economic and legal aspects of CCS.

Nanostructural Organization in Ionic Liquids

Abstract: Nanometer-scale structuring in room-temperature ionic liquids is observed using molecular simulation. The ionic liquids studied belong to the 1-alkyl-3-methylimidazolium family with hexafluorophosphate or with bis(trifluoromethanesulfonyl)amide as the anions, [Cnmim][PF6] or [Cnmim][(CF3SO2)2N], respectively. They were represented, for the first time in a simulation study focusing on long-range structures, by an all-atom force field of the AMBER/OPLS_AA family containing parameters developed specifically for these compounds. For ionic liquids with alkyl side chains longer than or equal to C4, aggregation of the alkyl chains in nonpolar domains is observed. These domains permeate a tridimensional network of ionic channels formed by anions and by the imidazolium rings of the cations. The nanostructures can be visualized in a conspicuous way simply by color coding the two types of domains (in this work, we chose red = polar and green = nonpolar). As the length of the alkyl chain increases, the nonpolar domai...

Ionic liquids and catalysis: Recent progress from knowledge to applications

Abstract: This review gives a survey on the latest most representative developments and progress concerning ionic liquids, from their fundamental properties to their applications in catalytic processes. It also highlights their emerging use for biomass treatment and transformation.