Adsorption butane

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... 

S. P. Nandi. Many parameters (e.g., helium density, heat of wetting, butane adsorption, etc.) for correlating coal rank pass through a minimum at ca. 85-90% carbon content. In the present paper another parameter—the average size of the micropores—has been shown to follow the same pattern. 

Pre-admitting of a noble gas influence the adsorption, while admitting a noble gas subsequently to butane adsorption has no influence at all. This is demonstrated in figure 6 for n-butane on MFI at 383 K. 

With an increase in carbon number of the adsorbate, the heat of adsorption should increase. Therefore an increase in the adsorbed amount from methane to butane would be expected. This trend can only be seen with methane and ethane, both being in equilibrium with the gas phase within the chosen equilibrium time of one hour. Propane and butane adsorption is markedly lower than expected which is due to the non-equilibrium situation. 

The hds of thiophen (623-673 K, 1 atm) over sulphided M0O3 was followed as a function of time. Thiophen conversion and butane formation increased to a maximum and then decreased to a steady value (ca. 1 h), whereas butenes increased continuously to steady values. The reaction proceeded by two independent pathways adsorption of thiophen through S followed by hydrogenation to butane adsorption parallel to the catalyst surface followed by hydrogenation via butadiene and S elimination. 

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...

Increasing the constant for n-butane adsorption onto S2 (1<2) also leads to a significant increase of 111% in the isobutane formation rate. 

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 ... 

The least relevant method is to take a sample of the activated carbon and test it. One might try to learn when the activated carbon has little or no more capability to transfer the mass of solvent vapor through the network of pores and enable it to be adsorbed on activated sites One might complete the carbon tetrachloride (CTC) test (Chapter 4.4) or its more safe replacement the butane adsorption test (Footnote 15). The reason why these tests aren t relevant in this service is that they can t be completed in a few minutes. They probably require off-site participation. And they are not inexpensive to complete. 

By contrast, butane adsorption resulted in an opposite behavior. Not only did the adsorbed volume decrease as the exchange level increased, but also the initial heat of adsorption declined steadily (from 90kjmor to 65kJmoH) as the sodium content decreased. All the samples showed a plateau of differential heat of butane adsorption around 60-65 kj mol . This contrasting behavior towards strong and weak bases can be interpreted on the basis of hard-hard and soft-soft acid-base interaction [188]. 

As a further means of characterizing microporosity, Centeno et al. (2003) made use of the adsorption of n-butane from low concentrations (from 100 to lO ppm) adsorbing on ACFMs (6-40 wt% bum-off). The adsorption of n-butane, at low concentrations, takes place in pores of < 1 nm dimension. The widening of the microporosity is seen in Figure 4.25 where for the carbon (ACFM30) which had a maximum of n-butane adsorption at concentrations of 100 and 500ppm, the micropores had dimensions of 0.63-0.76nm. 

Butane adsorption it gives an indication of the applicability in solvent recovery and other gas-phase applications. The usual test consists in the determination of the adsorption of -butane at near ambient temperature, and for some applications such as gasoline vapor recovery in automotive vehicles the adsorption and desorption capacity are measured in a specific number of cycles. 

The adsorption enthalpies fiir n-butane determined in this work are in the (rather wide) ran of those reported in the literature. Hu et d. [12] and Do and Do [13] determined adsorption enthalpies of approximately 16 and 35 LI moT in the micropore and meso-macropore region, respectively. Allen et al. [14] measured isosteric heats of adsorption of 32 and 66 kJ mol" for n-butane adsorption over a non-porous carbon and over a molecular sieve carbon, respectively. Liu et al. [15] determined an adsorption enthalpy of 53.9 kJ mol" at zero coverage. Linders et. al. [16] fmmd adsorption enthalpies between 45 and 50 kJ moT for two diflEerent carbons in a Multitrack apparatus a technique similar to the TAP system described... 

The TAP reactor allows the fast and simultaneous determination of adsorption and diffiision parameters in activated carbons for the low-pressure limit. The adsorption and diffiision parameters determined agree well with those values obtained by other authors for n-butane adsorption over different activated carbons. The determined adsorption enthalpies are very high and almost do not depend on carbons, which means that all the samples have micropores whose dimensions are close to the n-butane molecular size. A TAP pulse response experiment allows gas access into the micropores. The value of the diffiision coefficient decreeises linear with decreasing pore size. 

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