Pressure, effect hydrocarbons

As previously discussed, the charts of K values are available, but do apply primarily to hydrocarbon systems. Reference 79 presents important other data on K value relationships. See Figures 8 4A and 8-4B for charts with pressure effects included (not ideal, but practical charts). 

The effects of pressure on hydrocarbon types in the liquid products (400°F fraction) and the carbon/hydrogen ratio in the total oil are... 

When the restriction of a simple hydrate is removed, the addition of a small amount of a second, larger hydrocarbon sometimes has a dramatic effect on the hydrate formation pressure. Consider the hydrate formation pressure effect of adding a small amount of propane (C3H8) to methane (CH4), and how such effects may be interpreted in terms of molecular structure. 

In a study of pressure effects on sodium and potassium decanoate micelles, the frequency of the CH2 stretching band was found to increase with pressure, with a discontinuous drop at the critical coagelization pressure (75). These results indicate that external pressure applied to micelles induces hydrocarbon tail disordering, even at pressures as high as 20 kbar, followed by a large increase in tail ordering upon coagel formation. 

Pressure effects are, in general, not significant in the range of commercial pyrolysis interests. For hydrocarbon partial pressures of 0.2 to 2.0 x 105 Pa, few differences are seen. When pressures are increased to the range of 50 to 100 x 105 Pa, however, the global rate constants sometimes double. 

The main aim of the present work has been to study the effects of the direct factors (which determine the coking rate in steam reforming) on the length of the induction period of coking and various ways of catalyst pretreatment (without or with the initiation of coking at a relatively high partial pressure of hydrocarbon) on the steady-state rate of coking,... 

The behavior of flammability limits at elevated pressures can be explained somewhat satisfactorily. For simple hydrocarbons (ethane, propane,..., pentane), it appears that the rich limits extend almost linearly with increasing pressure at a rate of about 0.13 vol%/atm the lean limits, on the other hand, are at first extended slightly and thereafter narrowed as pressure is increased to 6 atm. In all, the lean limit appears not to be affected appreciably by the pressure. Figure 25 for natural gas in air shows the pressure effect for conditions above atmospheric. 

With the increase in relative pressure of hydrocarbon vapor, i.e., with the increase in its activity, the plasticizing effect on the polymer becomes stronger, resulting in the increase in permeability (see Figures 9.11 and 9.12 Table 9.2). 

The present paper attempts to follow the reactions of n-hexane on a 0.5% Pt-HZSM catalyst. The effects of hydrocarbon pressure effects (p(nH) = 10 and 40 Torr) and temperattare (600 to 690 K) have been studied. Results will be comp2ired with those obtained on other Pt-zeolite catalysts [13, 14]. A fourfold increase of the hydrocarbon pressure accelerated the specific reaction rates (per mass unit Pt) with most zeolite-supported catalysts [13]. The rate over a nonacidic Pt/Si02 was much less sensitive to p (nH). 

In intramolecular Diels-Alder reactions, two new rings are formed. There are examples of relatively large pressure-induced accelerations which can be exploited for preparative purposes (Scheme 22 entries 1-5). These compounds, without exception, contain polar groups and are therefore not very suitable for the analysis of the relation between pressure effect and ring formation. The strong solvent dependence of the activation volume of the intramolecular Diels-Alder reaction shown in Scheme 23, entry 2, turned out to be largely the result of the strongly solvent-dependent partial molar volume of the reactant — y(reactant)—whereas the partial molar volume of the transition state [V = y(reactant)] appears to be almost unaffected by the nature of the solvents. The activation volumes of the intramolecular Diels-Alder reactions in the pure hydrocarbon systems (Scheme 23 entries 6 and 7) were found to be = —24.8 cm mol ... 

Fig. 8. Pressure effect on productivity in H.M.A. (A, A) and hydrocarbons (, 0) for Cat 1 doped with 0.2% of potassium (temperature 543K (closed symbols), 563K (open symbols) P= 1.5 MPa H2/C0= 2 GHSV= 1700 h"1).

Figure 6. Data showing effect of hydrogen partial pressure on hydrocarbon yield...

The carbon growth on optics has also been shown to be dependent on the mass of the hydrocarbon contaminant and the partial pressure of hydrocarbons, as well as on the EUV radiation dose and intensity. Experimental results obtained with model hydrocarbon compounds and showing the trends of carbon growth as a function of these parameters are shown in Fig. 14.15. EUV radiation intensity has a pronounced effect on contamination, which appears to initially grow rapidly as the intensity is increased, eventually reaching a plateau. In a similar manner. 

A negative partial pressure effect was observed in the oxidation of all the hydrocarbons. The potential decreases by about 70 mv per decade increase of pressure at constant current density. At constant potential, 8 log i/0 pH = 0.5. The usual Arrhenius temperature dependence was observed with an apparent activation energy of 22 kcal mole at the reversible potential, calculated by extrapolation from the Tafel region. Radiotracer studies showed that adsorption isotherm is Langmuirian, and that high coverages are obtained in the potential and concentration range studied. 

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