Hydrogen Henry coefficient

Dupont et al. [60] studied the same reaction, but used [BMIM][PF6] and [BMIM][BF4] as ionic liquids. A special focus of their investigations was on the influence of H2-pressure on conversion. The Henry coefficient solubility constant was determined by pressure drop experiment in a reactor, which is a known procedure to measure gas solubilities [93]. The values reported by these authors were FC=3.0xl0-3 mol IT1 atm1 for [BMIM][BF4]/H2 and 8.8x10 4 mol L 1 atm-1 for [BMIM][PF6]/H2 at room temperature, which differ significantly from those determined by the 1H-NMR technique (see Table 41.2) [59]. However, their values indicated that molecular hydrogen is almost four times more soluble in [BMIM][BF4] than in [BMIM][PF6] under the same pressure. According to the authors, this is reflected by the values of conversion (ee), which were 73% (93% ee) for [BMIM][BF4] and 26% (81% ee) for [BMIM][PF6] at 50 bar H2 pressure (Table 41.9, entries 2 and 4). 

In this formula, [H2] is the concentration of hydrogen in the liquid in equilibrium with the gas phase, related by the Henry coefficient. 

This simplified description of molecular transfer of hydrogen from the gas phase into the bulk of the liquid phase will be used extensively to describe the coupling of mass transfer with the catalytic reaction. Beside the Henry coefficient (which will be described in Section 45.2.2.2 and is a thermodynamic constant independent of the reactor used), the key parameters governing the mass transfer process are the mass transfer coefficient kL and the specific contact area a. Correlations used for the estimation of these parameters or their product (i.e., the volumetric mass transfer coefficient kLo) will be presented in Section 45.3 on industrial reactors and scale-up issues. Note that the reciprocal of the latter coefficient has a dimension of time and is the characteristic time for the diffusion mass transfer process tdifl-GL=l/kLa (s). 

Under these conditions—the solid is considered as being completely wetted (by capillary action)—the activity of a compound will be considered as equal to its liquid concentration. The gas-liquid partition of the compounds is expressed using Henry coefficients He16 whose values are obtained by a standard Flash calculation (Grayson-Streed method if hydrogen is present). 

The solubility and thermodynamic properties of various gases in [BMIM][PFg] has been determined using a gravimetric microbalance [4]. Essentially, the solubility of CO2 (particularly relevant as a carbon source) was very high, with reasonable solubilities observed for ethylene, ethane, and methane and low solubilities for oxygen, carbon monoxide, and hydrogen (H2 could not be detected). Subsequently, Henry coefficient solubility constants ofhydrogen in [BMIM][BF4] and [BMIM][PFg]... 

The total reaction rate, presented in Figure 23.9, was calculated as rt t = rr + (1 g- ft is seen from Figure 23.9b that the reaction rate in liquid phase is lower than in gas phase. At 60°C and Px = 0.045 atm, the ratio fo/rL 20. Note that includes Henry coefficient for hydrogen, the... 

GHSV gas hourly space velocity of synthesis gas If (H2) solubility (Henry coefficient) of hydrogen in liquid paraffinic FT product k first order rate constant... 

Table 3 shows results obtained from a five-component, isothermal flash calculation. In this system there are two condensable components (acetone and benzene) and three noncondensable components (hydrogen, carbon monoxide, and methane). Henry s constants for each of the noncondensables were obtained from Equations (18-22) the simplifying assumption for dilute solutions [Equation (17)] was also used for each of the noncondensables. Activity coefficients for both condensable components were calculated with the UNIQUAC equation. For that calculation, all liquid-phase composition variables are on a solute-free basis the only required binary parameters are those for the acetone-benzene system. While no experimental data are available for comparison, the calculated results are probably reliable because all simplifying assumptions are reasonable the... 

Henry s law coefficient 3 = PA/CA for hydrogen dissolved in feed liquid = 2240 bar/(kmol/m3). 

The proposed catalyst loading, that is the ratio by volume of catalyst to aniline, is to be 0.03. Under the conditions of agitation to be used, it is estimated that the gas volume fraction in the three-phase system will be 0.15 and that the volumetric gas-liquid mass transfer coefficient (also with respect to unit volume of the whole three-phase system) kLa, 0.20 s-1. The liquid-solid mass transfer coefficient is estimated to be 2.2 x 10-3 m/s and the Henry s law coefficient M = PA/CA for hydrogen in aniline at 403 K (130°C) = 2240 barm3/kmol where PA is the partial pressure in the gas phase and CA is the equilibrium concentration in the liquid. 

Henry law coefficient. y for hydrogen dissolved in feed liquid (Pa = XCa where Pa is hydrogen pressure and Ca is equilibrium concentration in liquid)... 

HS02 ln Equation 2 is defined as a pseudo Henry s law coefficient that depends on the hydrogen ion concentration and encompasses the totality of the dissolved S(IV)aq species (3). 

The Rectisol process [667], [707], [711]-[715] seems to be the prime choice in partial oxidation plants. The process, invented by Lurgi and developed further by Linde, operates with chilled methanol, a cheap and readily available solvent, in which carbon dioxide, hydrogen sulfide and carbonyl sulfide (COS) are readily soluble at low operating temperatures of below - 30 °C. The Henry absorption coefficient for H2S is about six times higher than for C02-... 

Phj = hydrogen pressure H = Henry s law constant (atm/ft /mol) k = liquid film mass transfer coefficient a = interfacial area between gas and liquid fls = catalyst external area k = catalyst film mass transfer coefficient... 

Figure 12.9 For the fugacity of a supercritical solute(l) in a liquid solvent(2), the Poynting factor (PF) in FFF 5 (12.2.2) tends to compensate for the effects of the activity coefficient. This plot shows contributions to fugacities of hydrogen(l) in methanol(2) at 294.15 K. Points are the experimental data of Krichevskii et al. [3]. Horizontal line is for a Henry s law ideal solution. Upper line includes only the Poynting factor, while the lower line includes only the activity coefficient. Adapted from a figure in Campanella et al. [4].

In the relation (1), k m the Henry s law solubility coefficient for molecular hydrogen in the crystal. Experiment showed (12) that equation (1) was correct, so that hydrogen is both dissolved as molecules and diffuses as molecules. The derived value for D was 2-3 x 10 " cm. sec. at 680° C. 

The solubility of hydrogen sulfide in water at moderate pressures has been detomined by Wright and Maass (1932) and the behavior of the hydrogen sulfide-water system evaluated in more detail by Selleck et al. (1952) up to a pressure of 5,000 psig. Fortunately, the data from both of these investigations indicate that Henry s law holds reasonably well for the system at conditions which would normally be encountered in gas-purification operations. Equilibrium gas and liquid compositions can readily be calculated fiom Henry s law coefficients such as diose presented in Table 6-10. 

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