Adsorption ethane

As might be expected, ethane adsorption on MgO(lOO) is more complicated and is apparently characterized by short-range order. It seems that the size and shape of the C2H6 molecule play an important role in determining the structure of the 2-D film. 

In this paper, we present a model for activated carbon that takes into account the characteristics of the adsorbent that affect the adsorption of both polar and non-polar species. The structure of the carbon is represented by a PSD, obtained from the analysis of pure-ethane adsorption, and chemical heterogeneity is included by placing regularly distributed carbonyl sites on the surface of the pores. The single-pore isotherms for water and ethane are calculated by grand canonical Monte Carlo (GCMC) simulation. 

Figure 1 Pore size distribution of BPL activated carbon determined from the analysis of pure ethane adsorption at 273, 298 and 323 K.

Figure 2. Simulated isotherms for methane and ethane adsorption in single-walled carbon nanotubes of diiierent diameters.

For ethane, adsorption values of 4.04 wt% for DD3R were found while Na-A adsorbs 7.4 wt% at similar conditions (700 Torr, 25°C), so DD3R adsorbs 54.6% of the amount of ethane adsorbed on zeolite A. The accessible volume of DD3R is 0.48% compared with zeolite A, so based on the void volume, both materials show comparable adsorption of a non-polar molecule. The adsorption of ethylene amounts to 43.5 %, compared to zeolite A (3.65 wt% and 8.4 wt%, respectively). The slightly higher preference of zeolite A for an aUcene can be ejqrlained in terms of stronger interactions of an unsaturated hydrocarbon with the ionic nature of the zeolite A surfece. Calcium-exchanged type A zeolites were found to exhibit the same behaviour firr propane and propylene [38]. 

Fig. 14. Response of smooth platinum anodes during linear anodic potential sweep for ethane adsorption at 0.3 V in 1 Al liOO (174. The anodic and cathodic pretreatment schedule of the electrode is shown at the bottom of the figure. The sweep follows ethane adsorption for time Te, corresponding to the various curves.

Kazansky VB, Pidko EA (2005) Intensities of IR stretching bands as a criterion of polarization and initial chemical activation of adsorbed molecules in acid catalysis. Ethane adsorption and dehydrogenation by zinc ions in ZnZSM-5 zeolite. J Phys Chem B 109 2103... 

Stach et al. [211] found a Unear relationship between the adsorbed amounts of ethane and the differential molar heats of adsorption over three dealuminated mordenites. The heats of ethane adsorption on the different mordenites increased with decreasing Si/Al ratio, i.e. with increasing aluminum content of the framework. 

The last issue addressed here is prediction of supercritical adsorption of gases in porous carbons using the characteristic parameters of their internal structure probed by gas adsorption. The issue is not new but has not been well resolved due to mainly poor knowledge of carbon structure. In order to address this issue, we applied the results of the PSD and PWTD of BPL, obtained from interpretation of argon adsorption at 87 K using our proposed approach, to predict supercritical adsorption of simple gases such as methane, ethane. The results were then direetly compared wife those obtained finm the use of PSD calculated by infinitely thick pore wall model and experimental data, and demonstrated the better capability of our approach. As an example Fig. 4 below depicts the results for ethane adsorption on BPL... 

Figure 5. PSD obtained fiom the analysis of ethane adsorption at 263 K. The peak at smaller sizes corresponds to the channels, and the peak at larger sizes corresponds to fine cavities.

Figure 8. ExperimentBl (symbols) and simulated (lines) adsorption of nitrogen at 77 K. Dashed line prediction from the PSD obtained from the analysis of ethane adsorption. Solid line isotherm obtained by fitting the PSD to nitrogen adsorption data.

We presented two different types of model for PMSs a model based on kMC simulation of the synthesis process, which we applied to MCM-41 and a pore network model, which we applied to SBA-2. The parameters of the kMC-based model, which is the more fundamental of the two, were fitted to ethane adsorption data. The model was then used to predict adsorption in materials functionalised with surface organic groups, with excellent results. The pore network model for SBA-2 allowed us to determine the PSD of the cavities and the channels, and to obtain information on the pore network connectivity, and in particular the coordination numbers of the subnetworks accessible to different adsorptives. Taken together, these two studies have improved our knowledge of the structure of these materials, and have established that we can use these methods as tools for the design of PMSs as adsorbents and catalyst supports. 

The samples obtained were characterised by N2 and ethane adsorption at 77 and 264 K, respectively, usir an ASAP 2000 (Micromeritics) apparatus and an apparatus developed in the research group. Both gases had a purity of 99.99 %. The adsorption equilibria for pure ethane were determined using a bench-scale open-flow adsorption/desorption apparatus. A detailed description and a schematic representation of the apparatus can be found elsewhere[10]. In tins study, both apparatuses were used with dry sample weights from 2 g to 0.6 g depending on the availability of the sanple and its adsorption capacity. Each isotherm... 

It is difficult to imagine how stable and saturated gas molecules (H2, O2, etc.) form a chemical bond with a surface atom of the solid. To explain this bonding, we assume that in many cases, dissociation of the gas molecule is accompanied by adsorption. This can be eonfirmed experimentally by comparing hydrogen, nitrogen, carbon monoxide, and ethane adsorption on the nickel surface. The maximum amounts adsorbed are in the following ratios ... 

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