Conventional adsorption system

The application of adsorbents can be classified according to the adsorbents themselves, the chemicals to be cleaned up, the type of spill (i.e. large or small scale) and whether the spill liquid can be pumped to containers for conventional treatment or the type of chemical/water interaction (Robinson, 1979). Chemicals that mix with water can be treated in conventional adsorption systems, or adsorbents can be spread onto the spill and mixing achieved by agitation. For chemicals that float, booms, blankets, fibers, or powders are available. Applying sorbents to chemicals that sink is the most difficult application. Weighted sorbent bags and sacks have been developed. For this purpose, in addition, the use of dense adsorbents... 

Helium gas purification systems. Where the concentration of moisture and atmospheric contaminants in the helium stream are very low, e.g., about 500 parts per million or less and where the system is operating at low pressure, the helium stream may be cooled to low temperatures inside the Norelco circulating cold gas head, and thence purified in a conventional adsorption system as illustrated by the process diagram, Figure 10. Calculations show that a refrigerator of this type has the capacity to purify about 4000 SCFH of helium of the aforenoted specifications. 

Applications of carbon adsorption go far beyond conventional water treatment applications which we will discuss in a general sense shortly. Table 8 provides a summary of the key applications of carbon adsorption systems for liquid phase applications. 

The most active formulation (ZSNbPt) was tested in a conventional reactor using as feedstream a mixture of light n-alkanes [n-pentane (20 wt%), n-hexane (60 wt.%) and n-heptane (20 wt%)] to simulate an industrial stream. Experiments were carried out in a conventional reaction system using a fixed-bed continuous -flow reactor. Reaction was carried out under the same conditions as the poisoning resistance experiments. The activity and selectivity of this catalyst (Fig. 5.13) have been compared with those obtained with sulfated zirconia impregnated with platinum (ZS). Fig. 5.13 represents the evolution of the conversion with reaction temperature. Clearly, the reactivity of the n-paraffm follows the order n-heptane > n-hexane > n-pentane for both catalysts, as expected when taking into account the adsorption heats of the different hydrocarbons [34]. 

Experimental results by means of the volumetric method using a conventional BET system were observed to be Henry type in the temperature range 233-313 K and the pressure range P= 5-30 kPa, achieving the condition of small coverage. An example adsorption isotherm, for H-mordenite, is shown in Figure 17.3. 

Although differences in the adsorption capacities are apparent, no correlation between them and the surface areas of the carbons can be established. We can therefore conclude that the extent of the adsorption at the zero surface coverage should be more directly related to the adsorbate and pore size and shape than to the total surface area (or volume of pores) of the adsorbent. In connection with this, the adsorption of CO2 on activated carbons from diluted ambient environments, measured in a conventional gravimetric system, has recently been shown to be more closely related with micropore size distribution rather than with the surface area or volume of micropores [17]. 

The critical analysis of the numerical results placed in Tables 5-8 instructs that for a given adsorption system, one can obtain a comparably accurate descriptions (measured by the q values) of the experimental isotherms on the basis of different theoretical relationships. Since different adsorption equations relate to different paires of Bq and A values, thus it must be emphazised that the adsorbent structural heterogeneity description based on the method presented above has a conventional character and is, similarly as an adsorbent specific surface area, connected with the applied theoretical model. 

Much of the literature information concerning the influence of solvent on polymorph crystallization is derived from the conventional crystallization system. The effect of solvent appears to be dictated by kinetics rather than by thermodynamics (30). The solvent may act by selective adsorption to certain crystallographic faces of the polymorphs, thereby inhibiting their nucleation or retarding their growth to the advantage of others. Similar solvent behavior... 

Adsorption of NH3, C02 and H2 on the carriers and the supported Pd catalysts was carried out 1n conventional static system. The supported Pd catalysts were reduced by 13.3 kPa of H2 at 773 K for 1 h and evacuated under 10-2 Pa just before the adsorption experiments in the apparatus. The amounts of adsorbed gases were measured at 13.3 kPa for NH3 and CO2, and 1.33 kPa for H2 at r.t. The IR spectra of adsorbed pyridine on the carriers and the supported Pd catalysts were measured with an Analect fx-6200 spectrometer. The ESR spectra of adsorbed phenothiazine (TDPA) on several Pt catalysts were... 

Hexacarbonyl molybdenum Mo(CO)6 was successfully used to prepare intrazeolite molybdenum sulfide clusters in the cavities of NaY (CVD technique) [4,5,7,8]. The decomposition and sulfidation of Mo(CO)e encaged in NaY were extensively studied by Okamoto et al. [7-11] by means of temperature programmed decomposition (TPDE), XPS, and XAFS techniques. It has been claimed that the structure of molybdenum sulfides is described as molybdenum dinuclear sulfide clusters M02S4. de Bont et al. [12] supported the formation of molybdenum sulfide dimer species. The extremely high dispersion of molybdenum sulfide clusters prepared fi"om Mo(CO)6 was also suggested by an NO adsorption capacity much hi er than those of other conventional catalyst systems such as M0S2/AI2O3 [9]. 

Comparative investigations between the conventional adsorption/desorption method and PFG NMR have been carried out with aromatics in zeolite NaX. It was pointed out in Table 2 that there is still some divergence between the data obtained by both methods on intracrystalline diffusion. Table 3 compares the values for Tjnira and Tjn,ra determined by the NMR methods [143,175,176]. H PFG NMR measurements of these systems are complicated by the rather short transverse nuclear magnetic relaxation times, which range over milliseconds and lead to mean errors up to 50%. However, as with the n-paraffins in NaX, there is no indication of a significant enhancement of Tjn,ra 0 comparison with Tin,ra° " as... 

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