Adsorption rectangular

A unit referred to as the Higgins Loop has been popular ia water treatmeat, as well as other appHcatioas. Resia is pulsed at regular iatervals arouad a rectangularly shaped loop. The diameter of the adsorption section is larger than that of the regeneration section. 

The ACR Process. The first step in the SCR reaction is the adsorption of the ammonia on the catalyst. SCR catalysts can adsorb considerable amounts of ammonia (45). However, the adsorption must be selective and high enough to yield reasonable cycle times for typical industrial catalyst loadings, ie, uptakes in excess of 0.1% by weight. The rate of adsorption must be comparable to the rate of reaction to ensure that suitable fronts are formed. The rate of desorption must be slow. Ideally the adsorption isotherm is rectangular. For optimum performance, the reaction must be irreversible and free of side reactions. 

The solution to this model for a deep bed indicates an increase in velocity of the fluid-phase concentration wave during breakthrough. This is most dramatic for the rectangular isotherm—the instant the bed becomes saturated, the fluid-phase profile Jumps in velocity from that of the adsorption transition to that of the fluid, and a near shocklike breakthrough curve is obseived [Coppola and LeVan, Chem. Eng. Sci.,36, 967(1981)]. 

Centered rectangular lattice gases a model for the adsorption... 

Fig. 1. Interaction energies (f> between adsorbate atoms on (a) the square lattice, and (b) the centered rectangular lattice. These figures are for the purpose of qualitative illustration only and no assumptions are made about the actual geometry of adsorption sites on the substrate surface.

Fig. IS. Phase diagram of the H/Fe(110) system, as detenniiied from LEED intensities. Fuli dots represent experimentally determined data points shaded areas correspond to incommensurate or antiphase domain regions. A possible interpretation for the ordered (2 x 1) and (3 x 1) phases is indicated in Fig. 16, assuming that the adsorption sites form a centered rectangular lattice as shown in Fig. lb. (From Imbihl et...

Lietti and co-workers studied the kinetics of ammonia adsorption-desorption over V-Ti-O and V-W-Ti-O model catalysts in powder form by transient response methods [37, 52, 53[. Perturbations both in the ammonia concentration at constant temperature in the range 220-400 °C and in the catalyst temperature were imposed. A typical result obtained at 280 °C with a rectangular step feed of ammonia in flowing He over a V2O5-WO3/TiO2 model catalyst followed by its shut off is presented in Figure 13.5. Eventually the catalyst temperature was increased according to a linear schedule in order to complete the desorption of ammonia. 

According to their analysis, if is zero (practically much lower than 1), then the liquid-film diffusion controls the process rate, while if tfis infinite (practically much higher than 1), then the solid diffusion controls the process rate. Essentially, the so-called mechanical parameter represents the ratio of the diffusion resistances (solid and liquid film). The authors did not refer to any assumption concerning the type of isotherm for the derivation of the above-mentioned criterion it is sufficient to be favorable (not only rectangular). They noted that for >1.6, the particle diffusion is more significant, whereas if < 0.14, the external mass transfer controls the adsorption rate. 

Figure 1.6. Plan and side views of the structure of the Cu(410)-O surface phase. The full and dashed lines show respectively the primitive and centred rectangular surface unit meshes (that are unchanged from those of the clean surface by the adsorption).

Figure 4.9 Adsorption of surface-active molecules as an orientated monolayer at air-water and oil-water interfaces. The circular part of the molecules represents the hydrophilic polar head group and the rectangular part represents the non-polar hydrocarbon tail. At the air-water interface, the hydrocarbon chains will tend to lie horizontally on top of the water surface at low coverage, but will tend to assume more upright configurations at high coverage (see page 103)...

When the equilibrium constant b is large (highly favorable adsorption) the Langmuir isotherm approaches irreversible or rectangular form,... 

Mathematical analysis of the diffusion problem in this case for a rectangular parallelepiped adsorbent leads to an equation for the total moles of adsorptive that have entered the adsorbent pores by the elapsed time t (the time integral of the right side of Eq. 4.72) 39... 

H20 and Cl2 adsorption on cleaved CuInX2 (X=S, Se) surfaces have been investigated. The cleaved CuInX2 surfaces show the rectangular LEED pattern expected for the (Oil) face. Electrochemical investigations clearly indicate a reactive transformation of the surface during electrochemical treatment (Bachmann, 1984). 

The zeolite crystal is modeled here as a finite, two-dimensional rectangular grid of intersecting channels. The adsorption and the desorption of molecules take place at border sites only according to the characteristics of zeolites, and the diffusion of the sorbed molecules in the channels is modeled as a random walk process. The reaction occurB in sorbed phase. The simulation technique was described elsewhere [2, 3], and the simulation results are calculated as the follows ... 

Sharp LEED patterns consistent with a c(4 x 2)CO superstructure could be readily obtained by exposing clean Ni(l 11) to 30 L CO in UHV at room temperature as reported in the literature [45-51], Also in accordance with information published elsewhere [52] was the increase in the background intensity of the rectangular Ni(110) LEED pattern following dosing, attributed to the presence of an amorphous CO overlayer. No AES spectra or LEED patterns were recorded after CO adsorption prior to the electrochemical experiments, to avoid electron-induced decomposition [53],... 

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