Properties at high pressure

Thermodynamic properties at high pressures are of great interest for instance to Earth scientists who wish to understand the behaviour of the Earth s mantle, where pressures reach 100 GPa. To carry out energy minimizations in the static limit at non-zero pressures we minimize the enthalpy H = U + pV with respect to all the variables that define the structure, where p is the applied pressure and V the volume. When p is zero we regain eq. (11.7). 

Activity of solvent, volumetric data, properties at high pressure... 

After in the foregoing chapter thermodynamic properties at high pressure were considered, in this chapter other fundamental problems, namely the influence of pressure on the kinetic of chemical reactions and on transport properties, is discussed. For this purpose first the molecular theory of the reaction rate constant is considered. The key parameter is the activation volume Av which describes the influence of the pressure on the rate constant. The evaluation of Av from measurement of reaction rates is therefor outlined in detail together with theoretical prediction. Typical value of the activation volume of different single reactions, like unimolecular dissociation, Diels-Alder-, rearrangement-, polymerization- and Menshutkin-reactions but also on complex homogeneous and heterogeneous catalytic reactions are presented and discussed. 

In Chapter 3.2 the kinetics of high-pressure chemical reactions are presented. The measurement of kinetic data is then outlined in Chapter 3.3. At last, in Chapter 3.4, the calculation of transport properties at high pressure is considered. 

Gjemes, E. et al.(1995). EFP91. Theoretical and experimental investigation of coal and biomass combustion and gasiftcation properties at high pressure and temperature. Final report, Roskilde Risp National Laboratory, Ris0-R-839(EN), Denmark. 

Strichart CO2 has general anaesthetic properties at high pressures it drives things in the other direction, hypo-excitabihty. 

Bertucco, A., and Vetter, G., Thermodynamic Properties at High Pressure, Chapter 2 in High Pressure Process technology Fundamentals and Applications, Elsevier Science, Amsterdam, NL, 2001. 

Since the two explanations for permeability drifts are related, respectively, to creep and volume recovery following initial membrane ftibrication, it is not surprisirig drat the log-log permeability jriois are reasonably linear also. Both creep and volume recovery behavior are expected to be functions of temperature and the composition of the pressurizing medium, since a strongly sorbing permeant such as CO2 may affect both the dense layer and the support stnicture properties at high pressures. Unfortunately, definitive data to permit comparisons of flux declines in the presence of CO2 and inert atmospheres rue not available at present. 

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