Isotherm for argon

Fig. 3.2 Adsorption isotherms for argon and nitrogen at 78 K and for n-butane at 273 K on porous glass No. 3. Open symbols, adsorption solid symbols, desorption (courtesy Emmett and Cines). The uptake at saturation (calculate as volume of liquid) was as follows argon at 78 K, 00452 nitrogen at 78 K, 00455 butane at 273 K, 00434cm g .

Jura and Criddle (38) observe inflection points in the adsorption isotherms for argon on graphite at surface coverage of less than a monolayer. These are interpreted as... 

Polley, Schaeffer, and Smith (59) observe stepwise isotherms for argon, nitrogen and oxygen on graphite at -195° C. The steps become more pronounced as the graphiti-zation temperature of the carbon black adsorbate is increased. The steps appear at multiples of 0.85 Vm and are to be expected for homogeneous surfaces. 

Isotherms for argon at 87 K adsorbed on typical activated carbons are shown in Figs 7.8 and 7.9, along with the reconstructed isotherm resulting from the pore width distributions shown. 

The GCMC simulation can be readily performed for a set of pores of various widths of interest. The result will be a set of local isotherms. Of interest in pore characterization are the local isotherms for argon at 87.3 K and nitrogen at 77 K. The figures in Fig. 11.6 typically show the local isotherms of argon... 

Fio. 8. Adsorption isotherms for argon, nitrogen, and butane on porous glass No. 3. Open symbols, adsorption closed symbols, desorption (45b). 

As already mentioned, the choice of the supercooled liquid as reference state has been questioned by some workers who use the saturation vapour pressure of the solid, which is measured at the working temperature in the course of the isotherm determination. The effect of this alternative choice of p° on the value of a for argon adsorbed on a number of oxide samples, covering a wide range of surface areas, is clear from Table 2.11 the average value of is seen to be somewhat higher, i.e. 18 OA. ... 

Well as various samples of nonporous but amorphous silica. They found that the points fitted on to a common curve very closely, which may be plotted from Table 2.14. A corresponding curve, though based on fewer samples, was put forward for y-alumina. The two curves are close to one another, but the divergence between them is greater than that between different samples of the same substance. Standard isotherm data for argon (at 77 K) on silica have been obtained by various workers. ... 

Fig. 2.1. Adsorption isotherms of argon on silica gels (

Experimental isotherms from Barrer and Stuart (15) are used as a check on the present theory. Following the liquid filling theory of Dubinin (ll) and other (12, 13, lU), saturation values of for Argon on LiX at the various experimental temperatures are as follows ... 

A statistical thermodynamic equation for gas adsorption on synthetic zeolites is derived using solid solution theory. Both adsorbate-adsorbate and adsorbate-adsorbent interactions are calculated and used as parameters in the equation. Adsorption isotherms are calculated for argon, nitrogen, ammonia, and nitrous oxide. The solution equation appears valid for a wide range of gas adsorption on zeolites. 

Figure 2. Argon adsorption isotherms for microporous and nonmicroporous catalyst supports. The normalized Ar uptake is plotted as a function of relative saturation pressure.

Figure 3. Low pressure isotherm data for argon on halozeolite...

Figures 2 through 6 show the isotherms for neon, argon, hydrogen, deuterium, and methane. Heats of adsorption were calculated from these isotherms Ne 1650, H2 2350, D2 2400, Ar 4900, CH4 5900 cal. per mole.

Adsorption Data for Argon on Bone Mineral at —195°. In previous sections we have emphasized that the polarizability of the adsorbate on the polar bone mineral surface contributes to high heats of adsorption. For comparison we have made calorimetric measurements of the heat of adsorption of argon at —195° on the bare surface of bone mineral and on a methanol-covered surface. The data for differential heats of adsorption of argon at —195° are shown in Figure 3 and isotherms as measured on the pilot sample are recorded in Figure 4. 

Figure 11.19. Adsorption isotherm and corresponding microcalorimetric recording for argon at 77 K on Silicalite-I (reproduced courtesy of Y. Grillet and P.L. Llewellyn, personal communication).

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