Nitrous oxide adsorption

The energy of nitrous oxide adsorption is defined as the energy difference between (a) and (b)... 

Ramis, G., Busca, G. and Bregani, F. (1992). Nitrous oxide adsorption on vanadia-titania and tungsta-titania catalysts for the reduction of nitrogen oxides, Gazzetta Chim. Ital., 122, pp. 79-84. 

A. Rajendran, T. Hocker, O. Di Giovanni, M. Mazzotti, Experimental observation of critical depletion Nitrous oxide adsorption on silica gel, Langmuir 18 (2002) 9726-9734. 

Since nitrous oxide was cut off from the feed stream, the sum of evolved nitrous oxide and nitrogen is equal to the adsorbed amount of nitrous oxide on the catalyst in stationary state of the reaction. This amount is extremely small compared to that on CuO and this fact also implys that the adsorption of nitrous oxide could be the slowest step in the overall reaction of nitrous oxide decomposition on MgO. 

These kinetic relationships suggest the following reaction mechanism including the adsorption of nitrous oxide as the slowest step. 

The faster desorption of nitrous oxide than oxygen as shown in Figure 1 may also be explained by this interpretation because the adsorption of nitrous oxide through its nitrogen end would be weaker than adsorption through its oxygen end as had been pointed out by Zecchina, Cerruti and Borello for adsorption of N2O on Chromia (10). 

The desorption of oxygen which was suggested as the slowest step on CuO catalyst is the rupture of a M-0 bond in its nature and the adsorption of nitrous oxide through oxygen end which was suggested as the slowest step on MgO catalyst is the formation of a M-0 bond. Therefore, the results we have obtained in the present study appears to be consistent to the conclusion proposed by Vijh. 

In the metal-catalyzed decomposition of nitrous oxide—corresponding to this conception—not the liberated 0 atom [C. Wagner (10)], but the N2O molecule receives electrons on adsorption (8,9,58). As the metal surface thereby loses electrons, it is to be expected that an increase of the work function will occur upon adsorption of N2O molecules, e.g., on platinum, even at such low temperatures that the thermal decomposition of N2O does not occur. 

Fig. 24. Adsorption of nitrous oxide on a platinum surface. Ordinate photoelectric yield I in electrons per light quantum. = 265.5 mg T = 83°K. (a) smashing of the N2O capsule (6) complete removal of the liquid air from N2O [according to (58)].

Fig. 25. Resistance increase of a transparent nickel film (90 X 10 atoms/sq. cm.) on the adsorption of nitrous oxide at T = 90.3°K. [according to (18)].

L. B. Richardson and J. C. Woodhouse studied the absorption of mixtures of carbon dioxide and nitrous oxide by charcoal S. J. Gregg, the heat of adsorption D. H. Bangham and F. P. Burt, the adsorption of nitrous oxide by glass and W. A. Patrick and co-workers, by silica gel near the critical temp, of the gas. 

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. 

Sanderson (1940) observed up to six-fold differences in the ability of soils to adsorb hydrocarbons in his laboratory. He also noted that the adsorptive characteristics of the colloidal soil systems would vary slowly with moisture content, time and season. Of particular significance was his observation that the adsorptive capacity for hydrocarbons on wet soil was only a small fraction of that for dry soil. A further complication is created by near-surface biological activity that creates wide variations in the content of carbon dioxide, nitrous oxide and other biological gases. Overcoming all these problems is probably impossible however, it will suffice if the gases are liberated in proportion to the amounts present so that the analytical results bear some relationship to one another, and allow identification of potentially prospective areas. 

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