Physical Chemistry of High Polymers

The study of phase equilibria in hydrogen-containing mixtures is essential for petroleum and chemical engineering, electricity production, transportation and for many other energy needs. Fluid-phase diagrams are however atypical because of the size-asymmetric nature of these mixtures and the quantum behavior of hydrogen. Therefore, the development of a thermodynamic model able to accurately predict the phase behavior of such systems over wide ranges of pressure and temperature is a difficult and challenging task. In this work, the H2 group is added to the well-established PPR78 model in order to predict mutual solubility and critical loci of hydrogen-containing systems. Such a model combines the widely used Peng–Robinson equation of state (EoS) with a group-contribution method aimed at estimating the temperature-dependent binary interaction parameters [kij(T)]. In our previous papers, 15 groups were defined: CH3, CH2, CH, C, CH4 (methane), C2H6 (ethane), CHaro, Caro, Cfused aromatic rings, CH2,cyclic, CHcyclic ⇔ Ccyclic, CO2, N2, H2S, and SH. It was thus possible to estimate the kij for any mixture containing alkanes, aromatics, naphthenes, CO2, N2, H2S and mercaptans regardless of the temperature. In this study, the addition of the H2 group makes it possible to extend the PPR78 model to hydrogen-containing systems.

Phase equilibria in hydrogen-containing binary systems modeled with the Peng–Robinson equation of state and temperature-dependent binary interaction parameters calculated through a group-contribution method

Liquid + vapor equilibria in methane + ethene and in methane + ethane from 150.00 to 190.00 K

High-pressure vapor-liquid equilibria with cubic equations of state

The use of hydrogen (H2) as a substitute for fossil fuel, which accounts for the majority of the world’s energy, is environmentally the most benign option for the reduction of CO2 emissions. This will require gigawatt-scale storage systems and as such, H2 storage in porous rocks in the subsurface will be required. Accurate estimation of the thermodynamic and transport properties of H2 mixed with other gases found within the storage system is therefore essential for the efficient design for the processes involved in this system chain. In this study, we used the established and regarded GERG-2008 Equation of State (EoS) and SuperTRAPP model to predict the thermo-physical properties of H2 mixed with CH4, N2, CO2, and a typical natural gas from the North-Sea. The data covers a wide range of mole fraction of H2 (10–90 Mole%), pressures (0.01–100 MPa), and temperatures (200–500 K) with high accuracy and precision. Moreover, to increase ease of access to the data, a user-friendly software (H2Themobank) is developed and made publicly available. Machine-accessible metadata file describing the reported data: https://doi.org/10.6084/m9.figshare.12554804

/pdf/thermodynamic-and-transport-properties-of-hydrogen-3rxj5a97pt.pdf

Thermodynamic and transport properties of hydrogen containing streams

The vapor-liquid equilibrium relations of the hydrogen-methane, the hydrogen-ethylene, The hydrogen-ethane, the hydrogen-methane-ethylene and the hydrogen-ethylene-ethane systems were determined by a static method at several temperatures from -25°C to -170°C and at pressures up to 100 atm. From the data obtained, features of the phase equilibria of hydrogen-light hydrocarbon mixtures are discussed. The Benedict-Webb-Rubin equation was successfully applied to predict the vapor-liquid equilibria of the present systems above the normal boiling point of the heaviest hydrocarbon.

/pdf/vapor-liquid-equilibria-of-binary-and-ternary-systems-3otz9q56jx.pdf

Vapor-liquid equilibria of binary and ternary systems containing hydrogen and light hydrocarbons

The regular solution theory was applied to predict and correlate Henry''s constants for hydrogen, nitrogen, methane, ethane, and propane in hydrocarbon solvents. As the system temperature is above the critical temperature of the solute, the liquid properties of the supercritical component are hypothetical. In the present paper, a new method is proposed to estimate such hypothetical liquid properties. The calculated results represent Henry''s constants fairly well over a wide range of temperature, though a slight deviation remained in the region of very low temperatures and in the region near the critical temperature of the solvent. Thus, it was ascertained that the regular solution theory was applicable to predict and correlate Henry''s constants for nonpolar molecules. The present estimation for hypothetical liquid properties is considered to be adequate for nonpolar molecules.

https://www.jstage.jst.go.jp/article/jcej1968/8/2/8_2_93/_pdf

Calculation of henry''s constant of gases in hydrocarbon solvent by regular solution theory

The vapor-liquid equilibria of hydrogen-methane-propylene, hydrogen-ethylene-propane, and hydrogen-propylene-propane ternary systems were measured at temperatures from -100° to -25°C and at pressures from 20 to 80 atm. The experimental results agreed with those calculated by the BWR equation except for temperatures below the normal boiling point of the heaviest hydrocarbon. By using the vapor-liquid equilibrium data obtained, Henry''s constants for hydrogen in binary hydrocarbon solvents were determined. The nonideality of the solvent mixture was small, so that the regular solution theory was successfully applied to Henry''s constants for hydrogen in these mixed solvents.

Vapor-liquid equilibria and henry''s con-stants for ternary systems containing hydrogen and light hydrocarbons

The regular solution theory was applied to predict the vapor-liquid equilibria of cryogenic fluids, such as argon, nitrogen, oxygen, carbon monoxide, carbon dioxide, methane, ethylene, ethane and propane. When the system temperature is sufficiently below the critical temperature of each component, the vapor-liquid equilibria were well predicted by using the liquid properties at the saturation line of pure component. When the system temperature is close to the critical temperature of light component, good results were obtained by adjusting the liquid volume of the light component only. This liquid volume was determined by fitting calculated vapor-liquid equilibrium relations to the experimental results and was generalized as a smoothed curve. This generalized curve was also useful in estimating the hypothetical liquid volume. Vapor-liquid equilibria involving a supercritical component were predictable by using the hypothetical liquid fugacity and the solubility parameter obtained based on the generalized curve for the adjusted liquid volume.

Hiroshi Sagara

Papers

Vapor-liquid equilibria of binary and ternary systems containing hydrogen and light hydrocarbons

Calculation of henry''s constant of gases in hydrocarbon solvent by regular solution theory

Vapor-liquid equilibria and henry''s con-stants for ternary systems containing hydrogen and light hydrocarbons

Application of regular solution theory to vapor-liquid equilibria of cryogenic fluids