Carbon dioxide-hydrocarbon equilibria

K-factors for vapor-liquid equilibrium ratios are usually associated with various hydrocarbons and some common impurities as nitrogen, carbon dioxide, and hydrogen sulfide [48]. The K-factor is the equilibrium ratio of the mole fraction of a component in the vapor phase divided by the mole fraction of the same component in the liquid phase. K is generally considered a function of the mixture composition in which a specific component occurs, plus the temperature and pressure of the system at equilibrium. 

The reaction involves the transfer of an electron from the alkali metal to naphthalene. The radical nature of the anion-radical has been established from electron spin resonance spectroscopy and the carbanion nature by their reaction with carbon dioxide to form the carboxylic acid derivative. The equilibrium in Eq. 5-65 depends on the electron affinity of the hydrocarbon and the donor properties of the solvent. Biphenyl is less useful than naphthalene since its equilibrium is far less toward the anion-radical than for naphthalene. Anthracene is also less useful even though it easily forms the anion-radical. The anthracene anion-radical is too stable to initiate polymerization. Polar solvents are needed to stabilize the anion-radical, primarily via solvation of the cation. Sodium naphthalene is formed quantitatively in tetrahy-drofuran (THF), but dilution with hydrocarbons results in precipitation of sodium and regeneration of naphthalene. For the less electropositive alkaline-earth metals, an even more polar solent than THF [e.g., hexamethylphosphoramide (HMPA)] is needed. 

A soln. of sodium carbonate, Na2C03, absorbs carbon dioxide from the atm., forming some hydrocarbonate, NaHC03, and F. K. Cameron and L. J. Briggs studied the formation of sodium hydrocarbonate in soln. of the normal carbonate and found equilibrium was attained in about a week s time. The higher the temp. 

K. Buch measured the partial press, of ammonia and carbon dioxide in mixtures of ammonium carbonate and carbamate, and from the results calculated the cone, of the free and bound ammonia and higher carbonate, and of the carbamate and carbonic acid. The hydrolysis and equilibrium constants were then calculated. The hydrolysis constants Kx and K% and the equilibrium constant K3 of the hydrocarbonate to carbamate, were ... 

When applying an equation of state to both vapor and liquid phases, the vapor-liquid equilibrium predictions depend on the accuracy of the equation of state used and, for multicomponent systems, on the mixing rules. Attention will be given to binary mixtures of hydrocarbons and the technically important nonhydrocarbons such as hydrogen sulfide and carbon dioxide -Figures 6-7. 

BIOPLUME III is a public domain transport code that is based on the MOC (and, therefore, is 2-D). The code was developed to simulate the natural attenuation of a hydrocarbon contaminant under both aerobic and anaerobic conditions. Hydrocarbon degradation is assumed due to biologically mediated redox reactions, with the hydrocarbon as the electron donor, and oxygen, nitrate, ferric iron, sulfate, and carbon dioxide, sequentially, as the electron acceptors. Biodegradation kinetics can be modeled as either a first-order, instantaneous, or Monod process. Like the MOC upon which it is based, BIOPLUME III also models advection, dispersion, and linear equilibrium sorption [67]. 

Supercritical fluids are unique solvents and reaction media due to liquid like density and gas like viscosity. Diffusion is not limited by any interface. Under ambient conditions hydrocarbons and water are nearly unmiscible. Phase equilibrium changes significantly in the supercritical region of water (Tc = 647 K, pc = 22.1 MPa). Hydrocarbons and supercritical water become miscible at any ratio, whereas supercritical carbon dioxide and hydrocarbons still have a broad miscibility gap [4],... 

Table 3A.2 Experimental investigations vapor-liquid equilibrium (non-aqueous) for mixtures containing carbon dioxide and light hydrocarbons.

Huron, M.-J., G.-N. Dufour, and J. Vidal. 1978. "Vapor-Liquid Equilibrium and Critical Locus Curve Calculations with the Soave Equation for Hydrocarbon Systems with Carbon Dioxide and Hydrogen Sulphide" Fluid Phase Equil., 1 247-265. 

Smith J. T. and Ehrenberg S. N. (1989) Correlation of carbon dioxide abundance with temperature in clastic hydrocarbon reservoirs relationship to inorganic chemical equilibrium. Mar. Petrol. Geol. 6, 129-135. 

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