Butane adsorption isotherms

For propane, n-pentane and n-hexane the differential heats of adsorption over FER dropped more rapidly, right after 1 molecule was adsorbed per Bronsted acid site. Similar results were obtained with TON. In contrast, with MOR and FAU the drop in the differential heats of adsorption for n-alkanes occurred at lower coverages, indicating that only a certain fraction of the Bronsted acid sites were accessible to the adsorbing alkane probe molecules. With MFI the drop did not occur until 2 molecules of n-alkane were adsorbed per Bronsted acid site, suggesting perhaps a higher stoichiometry of about two n-alkanes per Bronsted acid site. In the cases of i-butane and i-pentane the drop occurred around one alkane per Bronsted acid site. Finally, n-butane adsorption isotherms measured over TON framework type catalysts having three different A1 contents (Si/Al2 = 90, 104, 128) showed Henry coefficients to increase with increase in the A1 content [5], Based... 

Fig. 15. Butane adsorption isotherms of ZnCt based activated carbois vrith heat treatment temperature at 773 K and Zn/precutsors ratios of (A) 0.24, (B) 0.48 and (D) 0.96. (C) was made at H IT of 1073 K and Zn/C of 0.96. Reprinted fiom [40], with permission from Elsevier...

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 .

Fig. 3.Z3 Adsorption isotherm of n-butane at 273 K on a sample of artificial graphite ball-milled for 192 b. The shoulder F appeared at a relative pressure which was the same for all six samples in the first milling run, all six in the second milling run, and also for two of the milled samples which had been compacted. The milling time varied between 0 and 1024 h, and the BET-nilrogen areas of the surfaces between 9 and 610 m g ...

Fig. 4.23 Adsorption isotherms of butane vapour at difTerent temperatures on a sample of carbon (prepared by heating a mixture of coke and pitch at 600°C), burnt off by 0.27%.

Fig. 5.5 Adsorption isotherms of butane at 0°C on Iceland Spar ground for 1000 h. Curve (i), the solid was outgassed at 25°C. Curve (ii), the solid was outgassed at 1S0°C. O, adsorption p Q, desorption.

It has been proposed that hydride transfer in zeolites requires the presence of two adjacent Brpnsted acid sites (69). In light of the above-mentioned theoretical examinations and also adsorption isotherms of 1-butene and n-butane on USY zeolites with various aluminum content (70), this proposition seems unlikely. 

Beyer and Belenykaia (27) have investigated the sorption properties of DAY zeolites prepared from Y zeolite and SiCl vapors. They reported a very low adsorption capacity for water and ammonia, similar to that of the almost aluminum-free silicalite (49). The low adsorption capacity for water is indicative of a hydrophobic zeolite surface. The adsorption isotherms for n-butane, benzene and n-hexane obtained on the aluminum-deficient zeolite have a shape similar to those obtained on NaY zeolite and are characteristic for micropore structures. They show the absence of secondary pores in this DAY zeolite. 

The amount of theoretical and experimental research focused on the interaction, equilibrium and dynamical properties of noble, simple and polyatomic gases within quasi-one-dimensional nanotubes is still limited [6-13]. Experimental adsorption isotherms have been reported for simple gases (Ar,N2) and alkanes (methane [11], ethane [12], propane-butane-pentane [13]) in monodisperse nanotubes of aluminophosphates. It is expected that similar experiment could be carried out soon in bundles of monodispersed carbon nanotubes. 

Brunauer and Emmett,2 however, take the view that, on porous iron catalysts, the first effect of van der Waals adsorption is to cover the surface with a layer one molecule thick. In the case of several permanent gases, and also of carbon dioxide and butane, if the adsorption isotherms are measured not too far above the boiling-point of the gases, the first layer is complete at 50 mm. pressure or less. If the pressure is raised up to atmospheric, further quantities are adsorbed, and there appears a nearly linear relation between the pressure, and the amount adsorbed in excess of the first monomolecular layer but the increase of adsorption, as the pressure is raised above that at which the first layer is complete, is much more gradual than the increase with pressure, at low pressures, before the surface is completely covered.3... 

Experimental data on single component adsorption isotherms of normal-butane and isobutane, on MFI zeolite, at 373K, for a pressure range of O.SkPa to 200kPa, were obtained. 

Hie influence of noble gasses on the adsorption isotherm is demonstrated in figure S for n-butane on FER at 383K. As the influence on the amount adsorbed is dependent on the loading the used of noble gasses influences the shape of flie isotherm. 

Adsorption isotherms of propane and C4 components on three adsorbents are plotted in Figure 2. Isotherm patterns of propane, n-butane, 1-butene and t-2-butene on zeolite A are very sharp in a low pressure region of less than lOOmmHg at 30 C (Figure 3-(a)). However isobutane isotherm shows almost the linearity in the region of experimental pressure. In case of CMS adsorbent, isobutane can t easily penetrate into the pore and resultantly shows a molecular exclusion effect at 30°C (Figure 3-(b)). The other components are considerably adsorbed on CMS. Uptakes of all the above C4 components on CMS are much slower than the corresponding components on zeolite A. 

In the original paper one of the major advantages put forward in favour of the Os method over the contenq)ary t method was that it allows a similar type of analysis of adsorption isotherms of other adsorptives, besides nitrogen, to be made. This is of particular importance in the case of activated carbons where it is customary to make use of a range of probe molecules of different size, shape, polarizability and polarity in order to carry out a more complete characterization. A number of authors have since demonstrated the general feasability of doing this and reference data for the adsorption of neopentane and butane, for... 

Application of eq. (8) to the adsorption isotherms for butane on silica gel showed one of the several ways in which the B.E.T. equation is superior to and more useful than the point B concept. As illustrated in Fig. 2 the adsorption isotherm for butane on silica gel is of such a shape as to make the picking of a point corresponding to a monolayer by the point B method very difficult if not impossible. Yet, the data when plotted according to eq. (8) yield a value for the surface area of the gel of 383 sq. meters/g. compared to a value of 477 sq. meters/g. obtained by nitrogen at —195° C. 

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

We now illustrate the utility of eq.(9.2-64) in the determination of diffusivities in a system of n-butane adsorption on activated carbon. The adsorption isotherm can be described by a Langmuir equation ... 

Fig. 3.20. Adsorption isotherms of propane and butane mixtuK on activated carbon amount adsorbed of propane and butane for propane pressures 0.76, 114 and 228Torr.

A Micromeritics ASAP 2010 gas adsorption analyser (stainless steel version) was used to measure the adsorption isotherms of ethane, ethene, propane, propene, -butane, and isobutane on Kureha carbon in the pressure range from 0.002 to 120 kPa. The instrument was equipped with a turbomolecular vacuum pump and three different pressure transducers (0.13, 1.33, and 133 kPa, respectively) to enhance the sensitivity in different pressure ranges. The static-volumetric technique was used to determine the volume of the gas adsorbed at different... 

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