Effect of total pressure

In equation 11.2, each partial pressure can be represented by the product of the mole fraction (ja etc.) and the total pressure (P in atm.) 

the mole fractions of products will increase with increasing pressure if r q, a relationship of considerable importance in seeking high conversions in methanol synthesis and ethylene hydration for example. 

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Vapor pressure is the most important of the basic thermodynamic properties affec ting liquids and vapors. The vapor pressure is the pressure exerted by a pure component at equilibrium at any temperature when both liquid and vapor phases exist and thus extends from a minimum at the triple point temperature to a maximum at the critical temperature, the critical pressure. This section briefly reviews methods for both correlating vapor pressure data and for predicting vapor pressure of pure compounds. Except at very high total pressures (above about 10 MPa), there is no effect of total pressure on vapor pressure. If such an effect is present, a correction, the Poynting correction, can be applied. The pressure exerted above a solid-vapor mixture may also be called vapor pressure but is normallv only available as experimental data for common compounds that sublime. 

Effects of Total Pressure on Uq and The influence of total system pressure on the rate of mass transfer from a gas to a licniid or to a solid has been shown to be the same as would be predicted from stagnant-film theory as defined in Eq. (5-285), where... 

To many, it seems counter intuitive that increasing the total pressure increases the vapor pressure, but such is the case. However, the change is small, and the effect of total pressure on vapor pressure can generally be ignored, unless large pressure changes are involved. 

Pressure variation. In Figure 17 are shown the effects of total pressure on the relative pressures (i.e., the ratio of the partial pressure to the total pressure) of silane, hydrogen, and disilane (Fig. 17a) and on the deposition rate (Fig. 17b). The RF frequency is 50 MHz, and the plasma power is 5 W. The relative pressure of hydrogen slowly increases, and the relative pressure of silane slowly decreases, both in model as well as in experiment. This is caused by an increase in silane depletion at higher total pressures, which results from a higher power dissipation... 

In like manner one can treat cases where the rate controlling step is adsorption or desorption of some species. Hougen (14) has considered the effect of total pressure on initial reaction rates for several cases where these processes are rate limiting. 

With methane, the marked dependence of —d[RH]/d[H20] on H2 concentration suggests that O or OH is the dominant attacking radical. The small effect of total pressure, as well as other evidence (6), rules out attack by O. The marked positive power in 02 cannot, however, be explained by the existing reactions since introducing either Reaction 22 or 24 would create a negative power in 02. The only feasible explanation is competition between the reactions ... 

Fig. 9. Effect of total pressure on dehydrocyclization of n-heptane over platinum-alumina catalyst (H7). Conditions 496°C., H2/HC = 5/1.

In the high temperature zone [29], the effect of total pressure on the maximum rate corresponded to an order of about 3.6 the order with respect to acetone alone is 1.0, and with respect to oxygen 2.2. 

FIGURE 11.19 Relation between gas hold-up and superficial gas velocity for different regimes of operation (a) effect of sparger resistance, (b) effect of total pressure and coalescing nature of the gas-liquid system. 

The effects of total pressure, height of submergence, and height of empty section on the number of plates have been studied as a function of the outgoing NO concentration (up to 20 ppm level). Figures 3-A, 3-B, and 3-C show the effect of height of empty section at weir heights of 0.025,... 

Figure 1. Effect of total pressure on the conversion of 2,2-dimethyl-1,3-propanediol ( ), and the selectivity for 2,2-dimethyl-3-amino-l-propanol ( ),...

If the effect of total pressure on the liquid fugacity is negligible in the neighborhood of the vapor pressure of pure component /, then... 

The effect of total pressure during coking with cyclopentane was 4... 

It contained 34 disks, 12 inches in diameter of Vg-inch-thick Transite. The hollow flat condenser plates, 35 in number, were roll-bonded from sheet copper. The unit was housed in a pressure vessel designed to allow the effect of total pressure level of air and other inert gases to be evaluated. 

A study was therefore made of the effect of total pressure, hydrogen-to-benzene ratio in the feed, and benzene decomposition on the gross heating value of the product gas. The study was limited to conditions at which ratios of hydrogen to methane in the product gas would be greater than that required to inhibit the presence of carbon at equilibrium. The results are presented on Figure 6. 

The effect of total pressure on the deposition rate present in Fig.4 is similar to that of flow rate. An increase in the pressure leads to an increase in the deposition rate. Further increase in the pressure does not affect the rate which reaches a plane. Among different studies on the variation of deposition rate with pressure, the results varied both qualitatively and quantitatively as described in introduction. Besmann explained the pressure dependence by involving two different deposition mechanisms. One mechanism was the direct decomposition of MTS to SiC via Rea.(2) as follows. CH SiCI, SiC+3HCI (2)... 

Figure 13. Effect of total pressure on the rate coefficient for the decomposition of (CH3)2CH0 radical , 333 K 343 K Q. 353 K O, 373 K. From A1 Akeel and Waddington (1984) with permission of the Royal Society of Qiemistiy.

The overall reversible reaction is A(g) - -B(g) C(g) -l-D(g), and a stoichiometric feed of reactants A and B enters a packed catalytic tabular reactor. Each component adsorbs on a single active site on the catalytic surface. Sketch the effect of total pressure on the initial rate of reaction when adsorption of reactant A is the slowest step in the overall mechanism and the stable reactive intermediate does not occupy surface sites. 

NiMnCo alloy RF magnetic sputtering Preparation of Ti02 films on NiMnCo aUoy and investigation of the effect of total pressure on the structure of TiOy, fdms [569]... 

S. S. Hla, G. J. Duffy, L. D. Morpeth, A. Cousins, D. G. Roberts, J. H. Edwards, Investigation of the effect of total pressure on performance of the catalytic water-gas shift reaction using simulated coal-derived syngases, Catal. Commun. 11 (2009) 272-275. 

The effect of total pressure on the carbonylation of methanol was also studied. In the range of 7.5-12.5 bar the pressure had a positive effect on the carbonylation reaction, increasing both the rate of acetic acid and of methyl acetate formation Figure 8). At higher pressures (above 12.5 bar), the increase in rate of ester formation became slower while the rate of acetic acid started to decrease. A total pressure of 11-12.5 bar looks to be the optimal for the carbonylation of methanol over the H[Rh(CO)2l2]/CDB catalyst, it is not needed to run the reaction at higher pressure. The selectivity towards acetic acid reached the best values even at lower pressure, at around 10 bar. 

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