Excess Capacities Research Articles

Topological investigations of mixtures containing cyclic ether and cyclic alkanones

Excess molar volumes, VE, excess isentropic compressibilities, κSE, excess heat capacities, CPE of 1,3-dioxolane (1)+cyclohexanone or cycloheptanone or N-methylpyrrolidin-2-one (2) mixtures have been determined using measured densities ρ, speeds of sound, u and molar heat capacities, CP over the entire composition range at 293.15, 298.15, 303.15 and 308.15K. The excess molar enthalpies, HE of the present mixtures have been measured at 308.15K. The analysis of VE, κSE, HE and CPE data (in terms of Graph theory), IR spectral data and quantum mechanical calculations of the studied mixtures suggest that (i) 1,3-dioxolane exists as a mixture of monomer and dimer; cyclohexanone, cycloheptanone exist as mixture of open and cyclic dimer; N-methylpyrrolidin-2-one exists as dimer (ii) 1,3-dioxolane (1)+cyclohexanone or cycloheptanone (2) mixtures are characterized by interactions among the hydrogen and oxygen atoms of the 1,3-dioxolane with the oxygen and hydrogen atoms of cyclohexanone or cycloheptanone respectively; (iii) in 1,3-dioxolane (1)+N-methylpyrrolidin-2-one (2), there are interactions between the oxygen atoms of 1,3-dioxolane with the oxygen and nitrogen atom of N-methylpyrrolidin-2-one. The VE, κSE, HE and CPE values calculated by Graph theory are consistent with experimental values.

Tailoring biomass-based activated carbon for CH4 storage by combining chemical activation with H3PO4 or ZnCl2 and physical activation with CO2

Coconut shell-based activated carbons intended for CH4 storage were prepared by chemical activation with H3PO4 or ZnCl2 and/or physical activation with CO2. Efforts were focused to establish relationships among the activation procedure, the textural and physical-chemical properties of the resulting materials and their volumetric CH4 uptake. The best results were achieved by using the combination of a relatively soft chemical activation with H3PO4 or ZnCl2, just the sufficient to minimize the presence of macropores originated from the botanical structure of the precursor, followed by physical activation with CO2 to develop a narrow pore size distribution mainly located around the optimum pore diameter/width for CH4 storage. This combined methodology permitted to obtain excess volumetric CH4 adsorption capacities as high as 94, 148 and 145 V/V for granular, powdered/compressed and monolithic carbons, respectively. The corresponding total CH4 storing capacities were estimated to be 102, 165 and 163 V/V. It is worthy to highlight that the precursor was a low cost and abundant agricultural by-product, which is very important for large-scale applications such as gas transportation and gas storage in vehicular fuel tanks.

Topological investigations of molecular interactions in binary ionic liquid mixtures with a common ion: Excess molar volumes, excess isentropic compressibilities, excess molar enthalpies and excess molar heat capacities

The densities, ρ, speeds of sound, u, and molar heat capacities, CP, of 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i)+ 1-butyl-3-methylimidazolium tetrafluoroborate (j); 1-butyl-3-methylimidazolium tetrafluoroborate (i)+1-ethyl-3-methylimidazolium tetrafluoroborate (j) and 1-butyl-2,3-dimethylimidazolium tetrafluoroborate (i)+1-ethyl-3-methylimidazolium tetrafluoroborate (j) mixtures at temperatures (293.15, 298.15, 303.15, 308.15)K and excess molar enthalpies, HE, for the same mixtures at temperature (298.15)K have been measured over entire range of mole fraction under atmospheric pressure. Using experimental data, excess molar volumes, VE, excess isentropic compressiblities, κSE, excess molar enthalpies, HE and excess molar heat capacities, CPE have been determined. The VE, κSE, HE and CPE data have been fitted to Redlich-Kister equation to estimate the binary adjustable parameters and standard deviations between experimental and calculated values. The topology of the constituent molecules (Graph theory) has been utilized to predict VE, κSE, HE and CPE data of the studied mixtures. The comparison of VE, κSE, HE and CPE values determined by Graph theory with their corresponding experimental values lends additional support to the proposed molecular entities existing in mixtures along with various processes involved in the (i+j) mixtures formation. Further, IR studies and quantum mechanical calculations support the presence of proposed molecular entities in the studied mixtures.

Heat capacities of aqueous binary and ternary mixtures (with piperazine) of N-(2-aminoethyl)-piperazine and N,N,N′-trimethylethylenediamine at temperatures (303.2–353.2) K

A new set of values for the molar heat capacities of N-(2-aminoethyl)piperazine (AEP) and N,N,N′-trimethylethylenediamine (tMEDA) and their aqueous mixtures over the whole range of compositions are reported in the present work. Molar heat capacities of ternary mixtures of each polyamine with piperazine (PZ): (AEP+PZ+H2O) and (tMEDA+PZ+H2O) were also measured. Measurements were done over the temperature range T=(303.2–353.2)K and p=101.3kPa by the differential scanning calorimetry technique. Excess molar heat capacities of aqueous binary mixtures were correlated with composition and temperature using a Redlich–Kister relation, which was then used to correlate molar heat capacities of the mixtures at different temperatures and compositions. The equation fit the results with the average absolute deviation (AAD) of 2.1% and 0.2% for the excess molar heat capacity and molar heat capacity, respectively. A modified Söhnel and Novotný equation was applied to represent the composition and temperature dependence of the molar heat capacity of aqueous ternary mixtures at AAD between the correlated and the experimental data of about 0.1%. The correlations proposed here are of acceptable accuracy for application in process design and engineering.

Beyond the Margules equation: a universal thermodynamic equation for solid solutions including coupled substitution, long- and short-range order

Equilibrium calculations in complex chemical systems involving solids require thermodynamic models for solid solutions. This article presents a formalism for solid solutions that assigns an energy contribution for a configuration consisting of a central atom and its neighbors, multiplying it with its probability based on site occupancies and sums the products up to give the total energy of the solid solution. The formulation is a closed-form expression allowing differentiation with respect to composition and hence the direct calculation of the chemical potentials. The formalism is applicable to multicomponent systems as well as to trace elements, handles long- and short-range order and can be applied to coupled substitutions. The necessary parameters can be obtained from force-field , DFT or other calculation methods capable of determining 0 K excess enthalpies and volumes of solid solutions. Because the excess enthalpies are also a function of temperature, methods to calculate excess heat capacities as a function of temperature might be necessary ( e.g . approximation by phonon density of states). For interactions with one neighbor the presented formalism reduces to the regular solution and for two neighbors to the Margules -equation. For a two-site solid solution with interaction to only the neighboring site and the possibility of interchanging atoms between the sites, this formalism reduces to the Bragg-Williams model. As an example, the formalism is applied to the system calcite–dolomite–magnesite and the necessary parameters are derived by computations using force-field methods. Due to the pure computational approach and the limitations of the force-field methods, the phase diagram and the state of order for the respective phases are only reproduced qualitatively.

Structure–property relationships in metal-organic frameworks for hydrogen storage

Experimental hydrogen isotherms on several metal-organic frameworks (IRMOF-1, IRMOF-3, IRMOF-9, ZIF-7, ZIF-8, ZIF-9, ZIF-11, ZIF-12, ZIF-CoNIm, MIL-101 (Cr), NH2-MIL-101 (Cr), NH2-MIL-101 (Al), UiO-66, UiO-67 and HKUST-1) synthesized in-house and measured at 77 K and pressures up to 18 MPa are presented, along with N2 adsorption characterization. The experimental isotherms together with literature high pressure hydrogen data were analyzed in order to search for relationships between structural properties of the materials and their hydrogen uptakes. The total hydrogen capacity of the materials was calculated from the excess adsorption assuming a constant density for the adsorbed hydrogen. The surface area, pore volumes and pore sizes of the materials were related to their maximum hydrogen excess and total hydrogen capacities. Results also show that ZIF-7 and ZIF-9 (SOD topology) have unusual hydrogen isotherm shapes at relatively low pressures, which is indicative of “breathing”, a phase transition in which the pore space increases due to adsorption. This work presents novel correlations using the modelled total hydrogen capacities of several MOFs. These capacities are more practically relevant for energy storage applications than the measured excess hydrogen capacities. Thus, these structural correlations will be advantageous for the prediction of the properties a MOF will need in order to meet the US Department of Energy targets for the mass and volume capacities of on-board storage systems. Such design tools will allow hydrogen to be used as an energy vector for sustainable mobile applications such as transport, or for providing supplementary power to the grid in times of high demand.

An international multi-laboratory investigation of carbon-based hydrogen sorbent materials

New materials are needed to achieve the hydrogen storage targets set out by the US Department of Energy for fuel cell vehicular applications. In order to enable the pathway toward this discovery, precise and accurate characterization of the hydrogen storage performance of these materials is needed. Determining the precise and accurate hydrogen storage capacity of materials requires rigorous attention to detailed experimental parameters and methodology. Slight errors in even small experimental details can result in a large deviation in the determination of the material’s true characteristics. Here, we compare measurements of the gravimetric excess hydrogen uptake capacities for two different carbon sorbent materials measured by different laboratories at ambient and liquid N2 temperatures. The participants for this study consist of research laboratories led by experienced scientists in the hydrogen storage field. This collaborative evaluation of standard sorbents illustrated considerable reproducibility over a broad range of materials’ hydrogen sorption gravimetric capacities.

Molar heat capacities of the mixture {1,8-cineole + ethanol} at several temperatures and atmospheric pressure

Molar heat capacities at atmospheric pressure have been determined every 5K for the mixture {1,8-cineole (1)+ethanol (2)} in the temperature interval (304.7 to 324.5)K and the whole composition range with a Calvet type calorimeter Setaram C80. From the molar heat capacities, excess molar heat capacities have been calculated, their values being positive and increasing as the temperature rises. The solvation model COSMO-RS has been applied to predict the excess molar heat capacities. The model overestimates the values of the excess heat capacities but predicts well the trend of variation of the excess molar heat capacity with the temperature.

Crowdsourcing: Global search and the twisted roles of consumers and producers.

Crowdsourcing spreads and morphs quickly, shaping areas as diverse as creating, organizing, and sharing knowledge; producing digital artifacts; providing services involving tangible assets; or monitoring and evaluating. Crowdsourcing as sourcing by means of ‘global search’ yields four types of values for sourcing actors: creative expertise, critical items, execution capacity, and bargaining power. It accesses cheap excess capacities at the work realm’s margins, channeling them toward production. Provision and utilization of excess capacities rationalize society while intimately connecting to a broader societal trend twisting consumers’ and producers’ roles: leading toward ‘working consumers’ and ‘consuming producers’ and shifting power toward the latter. Similarly, marketers using crowdsourcing’s look and feel to camouflage traditional approaches to bringing consumers under control preserve producer power.

Topological Investigations of Excess Heat Capacities of Binary and Ternary Liquid Mixtures Containing o-Chlorotoluene, Amides and Cyclohexane at 298.15, 303.15 and 308.15 K

Excess heat capacities, $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ and $$ \left( {C_{p}^{\text{E}} } \right)_{123} $$ , of binary tetrahydropyran (1) + N-methylformamide or N,N-dimethylformamide or cyclohexane (2), o-chlorotoluene (1) + cyclohexane (2), and ternary o-chlorotoluene (1) + tetrahydropyran (2) + N-methylformamide or N,N-dimethylformamide or cyclohexane (3) mixtures have been determined from their measured heat capacities, $$ \left( {C_{p}^{{}} } \right)_{{\text{mix}}} $$ and $$ \left( {C_{p}^{\text{E}} } \right)_{123} $$ , at 298.15, 303.15 and 308.15 K. The $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ and $$ \left( {C_{p}^{\text{E}} } \right)_{123} $$ values have been correlated using the Redlich–Kister equation to show their dependence on composition. The excess heat capacities, $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ , give information about the degree of non-randomness in the mixture. In this context, non-randomness contributes positively to $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ whereas randomness results in negative $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ values. The connectivity parameters of third degree, 3 ξ, of the constituent molecules, which in turn deal with topology, have been utilized (Graph theory) to compute $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ and $$ \left( {C_{p}^{\text{E}} } \right)_{123} $$ values of the investigated mixtures. The experimental $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ and $$ \left( {C_{p}^{\text{E}} } \right)_{123} $$ values compare well with those calculated from Graph theory. The excess heat capacities, $$ \left( {C_{p}^{\text{E}} } \right)_{12} $$ and $$ \left( {C_{p}^{\text{E}} } \right)_{123} $$ of binary and ternary mixtures have also been analyzed in terms of Flory’s theory.

Excess Heat Capacities of Binary Mixtures Containing o-Chlorotoluene and Pyridine or Isomeric Picolines or Aromatic Hydrocarbons

The excess molar heat capacities, \( \left( {C_{{P}}^{\text{E}} } \right)_{12} \), of binary mixtures of o-chlorotoluene (1) with pyridine, α-, β- or γ-picoline, benzene, toluene or o-xylene (2) have been measured as a function of composition at 298.15, 303.15 and 308.15 K using a micro differential scanning calorimeter (Model-μDSC 7 Evo). The \( \left( {C_{{P}}^{\text{E}} } \right)_{12} \) data have been fitted with the Redlich–Kister equation to calculate binary adjustable parameters along with standard deviations. The sign and magnitude of values of o-chlorotoluene (1) + pyridine or α- or β-picoline (2) are dictated by the relative proportion of components in the mixtures. However \( \left( {C_{{P}}^{\text{E}} } \right)_{12} \) values for o-chlorotoluene (1) + γ-picoline (2) mixture are positive and \( \left( {C_{{P}}^{\text{E}} } \right)_{12} \) values for o-chlorotoluene (1) + benzene or toluene or o-xylene (2) mixtures are negative over the entire mole fraction range. The topology of the constituent molecules has been employed (Graph theory) to determine the \( \left( {C_{{P}}^{\text{E}} } \right)_{12} \) data of the studied mixtures. It has been observed that \( \left( {C_{{P}}^{\text{E}} } \right)_{12} \) values obtained by Graph theory are in agreement with the experimental values.

Excess Molar Enthalpies and Heat Capacities of {2-Methylpiperidine–Water} and {N-Methylpiperidine–Water} Systems of Low to Moderate Amine Compositions

The systems {methylpiperidine–water} show partial miscibility that depends on the nature of the amine isomer. A thermodynamic analysis of these systems requires knowledge of excess properties of methylpiperidine isomers with water. Excess molar enthalpies were measured at pressure 0.5 MPa and temperatures from (303.15 to 338.15) K and from (308.15 to 328.15) K for 2-methylpiperidine and N-methylpiperidine, respectively. Specific heat capacities of pure and aqueous solutions of both methylpiperidine isomers were determined at 0.1 MPa and temperatures from (283.15 to 333.15) K.

Excess volumes and excess heat capacities of {1,2-alkanediol + methanol} mixtures and ionic volumes in these systems

Densities of {1,2-propanediol+MeOH}, {1,2-butanediol+MeOH} and {1,2-pentanediol+MeOH} mixtures and densities of dilute solutions of three electrolytes (NaI, NaBPh4 and Ph4PI) in mentioned mixtures with exception the system containing 1,2-pentanediol were measured at T=298.15K. Isobaric specific heat capacities for {1,2-propanediol+MeOH} and {1,2-pentanediol+MeOH} mixtures were measured using a differential scanning calorimeter over the temperature range from (293 to 324) K. The excess molar volumes and excess molar isobaric heat capacities of binary systems were calculated and fitted by the Redlich–Kister polynomials. For ternary systems apparent molar volumes of electrolytes were determined at an electrolyte concentration of 0.025molkg−1 over the entire mixed solvent composition range. Single ionic apparent molar volumes of transfer, ΔtVφ (ion) were calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption. The influence of the carbon–chain length over the obtained functions was studied. The results were analyzed in terms of intermolecular association.

Very high methane uptake on activated carbons prepared from mesophase pitch: A compromise between microporosity and bulk density

Two petroleum residues were pyrolyzed under two different conditions to obtain pitches with low or high mesophase content. The effect of the KOH: precursor ratio and the activation temperature on the packing density and porous texture of the carbons have been studied and optimized. Activated carbons combining high micropore volume (>1cm3/g) and high packing density (0.7g/cm3) have been successfully prepared. Regarding excess methane adsorption capacities, the best results (160cm3 (STP)/cm3 at 25°C and 3.5MPa) were obtained using the pitch with the higher content of the more organized mesophase, activated at relatively low temperature (700°C), with a medium KOH: precursor ratio (3:1). Some of the activated carbons exhibit enhanced adsorption capacity at high pressure, giving values as high as 175cm3 (STP)/cm3 at 25°C and 5MPa and 200cm3 (STP)/cm3 at 25°C and 10MPa (the same amount as in an empty cylinder but at half of the pressure), indicating a contribution of large micropores and narrow mesopores to adsorption at high pressure. The density of methane in pores between 1 and 2.5nm at pressure up to 10MPa was estimated to understand their contribution to the total adsorption capacity.

Excess heat capacities of mixtures containing 1-ethyl-3-methylimidazolium tetrafluoroborate, lactams and cyclic alkanones

The molar heat capacities, C P, of 1-ethyl-3-methylimidazolium tetrafluoroborate (1) + pyrrolidin-2-one or 1-methylpyrrolidin-2-one (2) + cyclopentanone or cyclohexanone (3) ternary mixtures have been measured at 293.15, 298.15, 303.15 and 308.15 K and 0.1 MPa using micro-differential scanning calorimeter. The observed C P data have been utilized to evaluate their excess heat capacities, $$ (C_{\text{P}}^{\text{E}} )_{123} $$ values, and same have been fitted to Redlich–Kister equation to predict ternary adjustable parameters along with their standard deviations. The Moelywn-Huggins concept (Huggins in Polymer 12:389–399, 1971) of interactions between the surfaces of constituent molecules in binary mixtures has been extended to ternary mixtures using topology of the constituent molecules to obtain expression (Graph theory) that predict correctly the $$ (C_{\text{P}}^{\text{E}} )_{123} $$ data of the present mixtures. The observed $$ (C_{\text{P}}^{\text{E}} )_{123} $$ data have also been analyzed in terms of modified Flory’s theory.

Insights on the physical adsorption of hydrogen and methane in UiO series of MOFs using molecular simulations

Molecular simulations were used to study the single component adsorption of H2 and CH4 in the iso-structural MOFs UiO-66, UiO-67 and UiO-68. The energetic landscape and the adsorption sites for the two gases are analyzed in detail while the pure component adsorption results are discussed in terms of excess adsorption capacities and isosteric heats, highlighting the limitations of the UiO pore topology for the adsorptive storage of H2 and CH4. It is shown that adsorption occurs primarily due to the interactions between the linker and the guest molecules.We furthermore analyze the performance of the UiO series for H2 and CH4 storage either at 77K or at 298K. At 77K the unique topology of the UiO structures enhances the fluid–solid interactions and it is shown that the excess H2 adsorption capacity of UiO-66, at 1bar as well as the maximum adsorption excess of UiO-68 surpass most of the known MOF structures (including MOF-7, MOF-177 and HKUST1). On the other hand at room temperature the theoretical adsorption limit of these MOFs for both H2 and CH4 is rather moderate.

Contemplation of global steel industry future using scenario approach

The protracted downturn in global steel market continues deteriorating the steel industry margins. Chronic overcapacity and volatility of raw material prices are the most influential and uncertain factors that shape the profitability of steel producers. These critical uncertainties are laid in the basis for four alternative scenarios of the global steel industry that are described in the paper using narratives and causal diagrams. Scenarios helped to verify a few strategic options, some of which are traditionally used in the industry. The options were tested in scenario “wind tunnel” and were classified depending on their robustness in different scenarios. Analysis highlighted high value-added product development, quasi-vertical integration via supply contracts, and industry cooperation for demolishment of obsolete excess capacities as viable options, which could provide a serious enhancement of steel industry performance in most of the scenarios.

Self-Serving Altruistic Consumption and International Prices

Self-serving altruistic domestic consumption arises when foreign consumption contributes to the domestic utility of consumption. This is particularly the case when consumption saturated economies with excess capacities vie to increase their employment and expand their foreign trade to maintain their competitive advantage. As a result, the traditional presumption that consumption preferences are “selfish”, underlying traditional economic assumptions may be misleading. When the self-serving altruism is combined with economic reciprocity (embedded in countries’ preferences), globalization is a “win-win” economic development. Such situations have both consumption and price implications, depending on countries’ preferences, their cost structures and their trades. This paper is based on a Cournot model for two countries, each with a utility function of both countries’ consumption. An “altruism premium” is defined by the price one country pays to expand consumption in another. We assume both consumption demand and supply sides including trade between these countries and use a Nash conjecture to determine countries’ inverse demand functions (implying that consumption in one country takes for given consumption in another when deciding how much to consume as a function of price). On the supply side, optimal global supply is shown to lead to prices that are linearly related and a function of the countries preferences. We show that under certain circumstances there is no purchasing power parity (PPP), while in others, when prices are calculated net of their global marginal costs, there exists a PPP. Specific examples outlining the implications of such situations are considered.

Excess heat capacities of mixtures containing 1-methylpyrrolidin-2-one, chlorotoluenes and benzene

Excess heat capacities, (CPE)ijk of {1-methylpyrrolidin-2-one (i)+benzene (j)+o- or m- or p-chlorotoluene (k)} and CPE of their sub-binary {1-methylpyrrolidin-2-one (i)+benzene (j)}; {benzene (i)+m- or p-chlorotoluene (j)} mixtures have been determined using their measured heat capacities data at T=(293.15, 298.15, 303.15)K and 0.1MPa using micro differential scanning calorimeter. The results are discussed in terms of Graph (which deals with the topology of the constituent molecules) theory. The results suggest that CPE and (CPE)ijk values commuted by Graph theory compare well with experimental values.

Thermodynamics of mixtures containing amines. XVI. of 1-butanol, 1-octanol or 1-decanol + benzylamine systems at (298.15, 308.15, 318.15 and 333.15) K

Molar isobaric heat capacities, Cpm, and molar excess isobaric heat capacities, CpmE, are reported for 1-butanol, 1-octanol or 1-decanol+benzylamine systems at (293.15, 308.15, 318.15, 333.15)K. CpmE values were measured with a Setaram Micro DSC II microcalorimeter using a scanning method. The investigated mixtures are characterized by large and positive CpmE(x1=0.5) values at 298.15K, which remarks that self-association and/or solvation effects are predominant in such solutions. The CpmE curves are skewed towards higher mole fractions of the alcohol, which suggests that alcohol-amine interactions are more probable in that region. In addition, for a given 1-alkanol, CpmE(x1=0.5) decreases when temperature increases, due to alcohol dissociation is larger at elevated temperatures. The lower self-association of longer 1-alkanols and lower solvation effects may explain that the CpmE(x1=0.5) change with temperature is sharper for the solutions with the mentioned alcohols. The observed decrease of CpmE(x1=0.5) with the increasing of the chain length of the alcohol at enough high temperatures may be explained in similar terms.