Carbon dioxide, adsorption

Carbon Dioxide Adsorption on Dried Polymer. Other unexpected interactions of these hydrolytic polymers have been noted previously during the measurement of infrared spectra of dried Pu(IV) polymers (like those used for diffraction studies). Vibrational bands first attributed to nitrate ion were observed in samples exposed to room air however, these bands were not present in samples prepared under nitrogen atmospheres (see Fig. 4) (6). Chemical analyses established enough carbon in the exposed samples to confirm the assignment of the extraneous bands to the carbonate functional group... 

In order to correlate this model reaction with physicochemical techniques, 2,6-dimethylpyridine and carbon dioxide adsorption followed by Infrared spectroscopy [2-4] which are generally used to respectively characterize the acidity and the basicity of aluminas were also undertaken. 

FIGURE 32.4 (See color insert following page 302.) The localized minima as obtained after the GCMS simulation with carbon dioxide adsorption over single-wall CNT with a fixed fugacity of 100 kPa. 

Carbonates, diaryl, reactions with cyclohepta-amylose, 23 240 Carbon dioxide adsorption, 21 44 on chromia, 20 27 on gallium-doped NiO, 22 247-251 on nickel catalysts, 22 87-96 dissociative, 22 93-96... 

Carbon dioxide adsorption causes changes in the sizes of all the zeolites studied similar to the variation observed for faujasite-type zeolites after water adsorption (Figure 6). For all zeolites, an increase in the adsorption of carbon dioxide leads to contraction this reached a minimum in the adsorption range 3-5.5 mM/gram. The final length of the pellets is below the initial value up to a relative pressure of p/ps 0.7 for zeolites CaA, CaY, and NaY while for NaA and NaX the contraction passes to an expansion, reaching 0.11% of the initial length at p/ps = 0.66 for NaX and 0.32 for NaA. 

Lozano-Castello D, Cazorla-Amoros D, Linares-Solano A, and Quinn DF. Micropore size distributions of activated carbons and carbon molecular sieves assessed by high-pressure methane and carbon dioxide adsorption isotherms. J. Phys. Chem. B, 2002 106(36) 9372-9379. 

In the case of H20, CO, and N20, experimental evidence has demonstrated that the principal interaction mechanism is also H bonding of Si-OH, to the C end of CO, to the O end of N20, and to the O atom in, H20 [124], Because of these properties, silica gel could serve as an excellent adsorbent for water vapor and pollution gases. Particularly, zeolites and silica gels are the adsorbents mainly applied today as dryers [129], An additional application of silica is hydrogen sulfide and carbon dioxide adsorptions [130,131],... 

Carbon dioxide adsorption by highly dehydroxylated titanium dioxides gives rise to bands that are best ascribed to a bidentate carbonate species. The corresponding band pairs were reported to appear at 1580 and 1320 cm-1 by Yates (132) and O Neill and Yates (268) and at 1584 and 1375 cm-1 by Primet et al. (176, 269) on anatase and at 1485 and 1325 cm-1 on rutile (132). These bidentate carbonate species are stable during pumping. 

Carbon Dioxide Adsorption on a BuOH/Li/Au(poly) Surface... 

Carbon dioxide adsorption was not considered in these conditions according to the conclusions reported by King [13],... 

Figure 1 shows CO2 adsorption isotherms and Table 1 contains the micropore volume calculated from both nitrogen and carbon dioxide adsorption isotherms. 

The observed results of carbon dioxide adsorption were presented in the form of CO2 isotherms in Fig. 1 and 2. Active carbon is a typical example for hydrophobic adsorbents whereas zeolite 4A is an example for hydrophilic adsorbents. For the former, specific pore volume accessible for benzene is 0.227 cm /g, whereas for the later, these pore volume was an order of magnitude lower, i.e. 0.021 cm7g. The volume of other pores, inaccessible for benzene is 0.017 cm /g for carbon and 0.172 cm /g for zeolite. It can be noticed, that active zeolite-carbon adsorbents have to be characterized by maximally developed structure of both kinds of pores. 

Adsorption microcalorimetry, finally, allows to check the differential enthalpies of adsorption derived from various adsorption isotherms through the isosteric method. What is more, it is much safer and meaningful in the first, raising, part of the isotherm, specially when it is close to the ordinate, such as for instance for carbon dioxide adsorption. This part is probably the most interesting from the viewpoint of specific interactions and gas separation or storage. 

Specific surface areas of various carbonized materials were measured by nitrogen gas adsorption with BET methods using an automated surface area analyzer (micro-track type 4200, Nikkiso, Japan). For mesopores whose diameter were less than SO nm, the surface areas and pore volumes were measured by carbon dioxide adsorption. The carbon dioxide adsorption at 298 K was measured with Bellsorp 28 (BEL Japan). The pore volume was determined using Dubinin-Radushkevich equation [4], and the surface area was determined by Medek s method [S]. 

A similar investigation of carbon dioxide adsorption on reduced nickel leads to the conclusion that the best agreement is obtained under the assumption that n is 3, i.e., that the CO2 molecule completely dissociates on adsorption (45). On the other hand, agreement is obtained for carbon dioxide adsorption on copper ferrite for w = 2. On ferric oxide the assumption of n = 1, tentatively suggested by the nearly direct proportionality... 

The marked discrepancy in the case of carbon dioxide adsorption on ferric oxide seems likely to be due not only to the existence of excited vibrational levels but perhaps also to rotational degrees of freedom in the adsorbed state. 

In their studies of carbon dioxide adsorption on copper oxide Garner and his associates (54) assume the formation of a carbonate ion held by forces of electrovalency to the oxide surface. A decision for or against this concept may be obtainable by a study of the exchange reaction, for... 

Surface properties of the samples were examined fi om nitrogen and carbon dioxide adsorption measurements. 

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