Adsorption distillates

Membrane absorption Membrane distillation Adsorptive distillation... 

Chromatography including extraction, ion exchange, adsorption Distillation, volatilization Electrolysis, electrodeposition... 

One adsorber holds a charge of charcoal ranging from 500 to 2000 kg, depending on the dimensions of the charcoal grains. A complete adsorption cycle comprising adsorption, distillation, drying and cooling lasts 14-18 hr. 

Among hybrid separations not involving membranes, adsorptive distillation (87) offers interesting advantages over conventional methods. In this technique a selective adsorbent is added to a distillation mixture. This increases separation ability and may present an attractive option in the separation of azeotropes or close-boiling components. Adsorptive distillation can be used, for instance, for the removal of trace impurities in the manufacturing of fine chemicals (it may allow for switching some fine chemical processes from batchwise to continuous operation). 

Although considered by some authors a novel process, adsorptive distillation is a relatively old hybrid separation, originating in the early 1950s (196). It is a... 

Despite an almost 50-year history, no large-scale commercial processes using adsorptive distillation have been reported so far. Some potential application fields for this hybrid separation are listed in Table 7. 

Figure 7 Scheme of an adsorptive distillation system for the separation of azeotrope-forming components A and B (S-adsorbent). 

Figure 8 Simplified scheme of an adsorptive distillation-based separation of closely boiling hydrocarbon mixtures. (From Ref. 197.)... 

TABLE 7 Potential Application Fields of Adsorptive Distillation Reported in the Literature... 

HerbstWA. Adsorptive distillation. U.S. Patent 2,665,315, Standard Oil Development Company, 1954. 

Marple S, Jr, Foecking NJ. Adsorptive distillation process. U.S. Patent 2,768,942, Shell Development Company, 1956. 

Chemical/physical treatment processes are those in which a chemical reaction is used to alter or destroy a hazardous waste component. Chemical treatment techniques can be applied to both organic and inorganic wastes, and may be formulated to address specific target compounds in a mixed waste. Typical chemical treatment processes include oxidation-reduction reactions such as ozonation, alkaline chlorination, electrolytic oxidation and chemical dechlorination. Physical treatment processes separate waste component by either applying physical force or changing the physical form of the waste. Various physical processes include adsorption, distillation, or filtration. Physical treatment is applicable to a wide variety of waste streams but further treatment is usually required. 

Furfural 10-15 Adsorption, distillation Plastic and lacquer industries... 

The most common processes today are sedimentation, filtration, flocculation, adsorption, distillation, and solvent evaporation. These treatment methods are used for phase or component separation purposes. 

Extraction, Chromatographic Adsorption, Distillation and Mass Spectrography... 

Analyte Separation/Concentration Enrichment, separation, isolation, concentration, matrix or compound separation, physico-chemical separation, hydride generation, cold vapor generation (Hg), solvent extraction (complexation), precipitation/coprecipitation, chromatography (including extraction, ion exchange, adsorption), distillation, volatilization, electrolysis, electrodeposition... 

The above examples indicate that selective separating methods are of particular importance for complicated separations. Systematic experimental work will Undoubtedly open up further applications. The combination of the distillation process with adsorption effects led to the technique called adsorptive distillation. The influence of the nature of the packing material on the efficiency of the separation of the mixture water-acetic acid has been studied by Fuchs and Roth [93]. 

The measurement and supply of gases and vapours are required in low-temperature distillation (c/. section 5.3.1), in carrier vapour distillation (section 6.1) and in adsorptive distillation (section 6.3). A neutral atmosphere (usually nitrogen) is often necessary in the distillation of inflammable, oxidizahle or hygroscopic material, and here again gas volumes may have to be measured. 

A suitable combination of two separation techniques like distillation and adsorption leads to a desired separation of a mixture which is either infeasible or expensive with a single technique. This combination of the different separation techniques is called hybrid separation. The techniques of hybridization are viewed as the techniques of process integration. Stankiewicz [60] presented the examples of extractive distillation, adsorptive distillation, membrane distillation, membrane absorption/stripping, and adsorptive membranes. A detailed discussion on hybrid separation processes involving distillation and one of the separation processes, namely, absorption, desorption, extraction, adsorption and membrane processes is available [61]. 

Hybrid separators membrane absorbers, adsorptive distillation, membrane distillation... 

Knopf, F.C., and Rice, R.G., Adsorptive distillation Optimum solids profiles, Chem. Eng. Commun., 15(1), 109-124(1982). 

Adsorptive distillation is an integrated operation in, which adsorption is combined with distillation to separate the close boiling components or constant boiling liquid mixtures. It is a three-phase mass transfer operation in which the adsorbent, usually in the form of (fine) fluidized powder, is introduced into the eolumn along with an inert carrier gas. The adsorbent selectively adsorbs one of the eomponents and flows into the desorption column in, which the adsorbed eomponent is desorbed. Thus adsorptive distillation is successful in separation and in avoiding the formation of azeotropes. Most commonly used adsorbents in the industry are silica gel, activated carbon, zeolite and alumina. Though adsorptive distillation has been reported long back, its industrial and commercial applications are very limited. However, potential application fields for adsorptive distillation inelude separation of toluene/methyl eyclohexane, naphtha reformates, p-xylene/ m-xylene, etc. 

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