Distillation/adsorption

Propane-propylene Close-hoihng Acrylonitrile Alternative to simple distillation, adsorption... 

Membrane absorption Membrane distillation Adsorptive distillation... 

The asphaltenes are nonvolatile and remain in the residue when the crude is subjected to distillation. The resins are partially volatile and therefore may be present in the lubricating oil fractions of higher boiling point as well as in the residue. Among the many methods employed for the separation of these materials from the oil fractions are distillation, adsorption, chemical treatment, and precipitation by special solvents. 

Figure 1. Apparatus for simultaneous distillation/adsorption. (Reprinted with permission from ref. 11. Copyright 1984 de Gruyter.)...

Catalytic distillation Adsorption Olefinic alkylation Extractive mass... 

Vinyl acetate-ethyl acetate Propane-propylene Ethanol-isopropanol Hydrochloric acid-water Nitric acid-water Close-boiling Close-boihng Close-boihng Maximum-boiling azeotrope Maximum-boiling azeotrope Phenol, aromatics Acrylonitrile Methyl benzoate Sulfuric acid, calcium chloride for salt process Sulfuric acid, magnesium nitrate for salt process Alternative to simple distillation Alternative to simple distillation, adsorption Alternative to simple distillation Sulfuric acid process rehes heavily on boundary curvature Sulfuric acid process rehes heavily on boundary curvature... 

Estimate the cost of the proposed extraction operation relative to alternative separation technologies, such as extractive distillation, adsorption, and crystallization. Explore other options if they appear less expensive or offer other advantages. 

Figure 12. Simultaneous steam-distillation adsorption (SDA) head. (Reproduced with permission from Ref. 30. Copyright 1981, Walter de Gruyter Co.).

Membrane adsorption Membrane distillation Adsorptive distiiiation... 

Another possibility for the deactivation may be derived from the water from which electrolytic solutions are prepared. Very tiny amount of organic substances, such as surface active reagent, is recently contained in water These organic substances are sometimes very hard to remove by distillation. Adsorption of surface active reagents may deteriorate electrocatalytic activity of any electrode. 

Solvent extraction Extractive distillation Azeotropic distillation Adsorption... 

Catalyst separation from the reaction mixture is of primary importance for efficient product purification and catalyst recycling. This has usually been carried out through extraction, distillation, adsorption, and binding to an insoluble support [74]. 

The removal of either C or D as it forms can drive the reaction to completion. Several methods like distillation, adsorption, stripping and another chemical reaction are available for the removal one of the components. Several esterification reactions can be driven to completion by stripping of the water as it forms. If the relative volatility of water is high, as the in production of dibutyl phthalate from phthalic anhydride and n-butanol, the water can be removed by simple distillation.The water could be preferentially adsorbed (taking advantage of the smaller size of water using a molecular sieve like 3A or 5A zeolite) or by extraction using a suitable solvent. 

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]. 

In the vinyl-chloride process, because of the significant differences in the volatilities of the three principal chemical species, distillation, absorption, and stripping are prime candidates for the separators, especially at the high production rates specified. For other processes, liquid-liquid extraction, enhanced distillation, adsorption, and membrane separators might become more attractive, in which case the design team would need to assemble data that describe the effect of solvents on species phase equilibrium, species adsorption isotherms, and the permeabilities of the species through various membranes. 

In addition to heterogeneous azeotropic distillation, several alternative methods are available for ethanol dehydration such as extractive distillation, adsorption, and pervapo-ration. A comprehensive review of the subject, including 302 references, has been presented by Vane. A recent paper by Kiss and Paul claims that the heterogeneous azeotropic distillation process is more economical than adsorptive drying because of the large amount of energy required to regenerate the adsorbent. 

As opposed to distillation, adsorption processes come in many different physical embodiments and cycles. Below, four basic cycles and two combinations are describe in their simplest forms. Then recent uses and modifications of these cycles, as well as other new process cycles, are described. 

The reduction of the bioethanol cost and the increase of its competitiveness depend greatly on the production technology. Bioethanol technology consists of two phases the prodirction of raw ethanol and its further del dration. Azeotropic distillation, adsorption on molecular sieves and evaporation through the membrane are rrsed for ethanol delydration of [8]. 

Figure 2.11 Comparison of the primary energy usage for ethanol/water separation using traditionai distillation/adsorption process (Fig. 2.9) and hybrid membrane-assisted vapor stripping (MAVS Fig. 2.10) process. Minimum energy (from minimum work calculation) shown as reference. Assumptions 37% and 85% efficient conversion of primary energy to electrical energy and thermal energy, respectively, 0.02 wt% ethanol in stripping column bottoms, and 99.5 wt% ethanol product (0.5 wt% water).

The low Second Law efficiency of distillation/adsorption is apparent from the difference between the primary energy usage curves in Fig. 2.11. According to the values in the figure, for a 10 wt% feed, the traditional process has a Second Law efficiency of only 7.0%. That value is exactly in the middle of the range cited earlier for distillation/ adsorption for the same separation [10]. That efficiency falls to 6.4% and 3.3% as the feed concentration is reduced to 5 wt% and 1 wt%, respectively. By comparison, the Second Law efficiency of the MAVS process is over three times that of distillation/adsorption, 24.3% efficient for a 10wt% ethanol feed, faffing to 21.4% and 10.8% for 5 wt% and... 

Fermentation-derived lactic acid can be separated by several recoveiy processes, which include calcium precipitation, solvent extraction and electrodialysis.Other recovery techniques have also been reported such as direct distillation, adsorption, liquid surfactant membrane extraction, chromatographic approaches, ultrafiltration, reverse osmosis, drying, conventional electrodialysis as well as bipolar membrane electrodialysis. ... 

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