Acetone, adsorption

The performance of various solvents can be explained with the help of the role of these solvents in the reaction. These solvents help in keeping teth benzene and hydrogen peroxide in one phase. This helps in the easy transport of both the reactants to the active sites of the catalyst. The acetonitrile, and acetone adsorption data on these catalysts (Fig. 6), suggests that acetonitrile has a greater affinity to the catalytic surface than acetone. There by acetonitrile is more effective in transporting the reactants to the catalyst active sites. At the same time, they also help the products in desorbing and vacating the active sites. 

The AG° values of acetone adsorption decrease slightly in the sequence H2O,Me0H, NM. They are indicative of a weak physical adsorption at the Hg/solution interface. It is also evident that the Gibbs energy of adsorption is enhanced by the electric field, particularly at the point of adsorption maximum. Small values of AG , similar to those determined at the solution/air interface, attest to the absence of specific interactions cf acetone with the mercury surface (which is opposite to the TU adsorption case). Hence, the solute-solvent interaction in the solution is an important factor in the adsorption of acetone, as shown for the zero charge on the Hg electrode in Fig. 11. 

Although experimental methods for estimation of this parameter for ketones are lacking in the documented literature, an estimated value of -0.588 was reported by Ellington et al. (1993). Its miscibility in water and low Koc and Kow values suggest that acetone adsorption to soil will be nominal (Lyman et al, 1982). 

The formation of methane has been proved by Fink (245, 246) and Deo et at. (247) by mass spectrometry to occur on acetone adsorption on alumina. This surface reaction thus lends some support to the assumption of basic OH" ions on the surface of alumina and titanium dioxide (see Sections IV.D.l and 2). 

With Cr203, neither sulphiding nor sulphur-containing gas phase additives, which also sulphided the surface, inhibited acetone deposition. This reflected the different mechanism involved in carbon deposition on this oxide such that whether the surface anion was either oxygen or sulphur, did not affect either acetone adsorption or the subsequent decomposition of the adsorbed molecules. 

Radha and Swamy (1985) studied the reaction of 2-propanol to acetone and hydrogen over La2MnM06 (M = Co, Ni, Cu). By monitoring the change in conductivity of the oxides upon acetone adsorption, they concluded that the surface is predominantly covered with acetone under their reaction conditions. In turn, the desorption of acetone is the ratedetermining step involving electron transfer from the surface to the adsorbed species. 

The aldol condensation of acetone to form diacetone alcohol is a well known reaction catalyzed by basic catalysts. This is also regarded as one important reason for the deactivation of MBOH reaction over alkali-exchanged X and Y zeolites ° Thus the pure acetone vapour was introduced into the infrared cell which contains fresh zeolite samples. It is found that the spectra after acetone adsorption are nearly completely the same as those obtained after MBOH reactions ° except for the region around 3400 cm where the spectra after MBOH reaction at 180°C still showed some bands belonging to the residual adsorbed MBOH. Figure 2 shows the IR spectra of alkali exchanged X zeolites and other Na exchanged zeolites... 

The DRIFT spectra of adsorb metal acetyl acetonates show different band intensities indicative for diffisient metal acetyl acetonate loadings, while different band positions and relative intensities are indicative for difi ent metal acetyl acetonate adsorption states on both supports. Furthermore, the spectra show a band at ca. 1635-1640 cm which is due to water physically adsorbed on the support surfiice at room temperature. 

The differential heats of adsorption of acetone adsorbed on H-ZSM-5 (at 360 K) and silicahte (at 350 K) over a wide range of surface coverage were reported by Sepa et al. [76]. The results were compared with ab-initio calculations of the reaction of acetone with model zeolite structures to form a stoichiometric hydrogen-bonded cluster-molecule complex [76]. The differential heats of acetone adsorption on H-ZSM-5 were approximatively constant around 130 kJ mol up to a coverage of one molecule per Al, after which the heats dropped to ca. 105kjmol [71], while on silicalite the heats of adsorption were constant over the entire range examined and equal to ca. 67 kJ mor. ... 

Fractional solution Acetone Adsorption on to activated arbon 2170... 

The developer is generally a solvent in which the components of the mixture are not too soluble and is usually a solvent of low molecular weight. The adsorbent is selected so that the solvent is adsorbed somewhat but not too strongly if the solvent is adsorbed to some extent, it helps to ensure that the components of the mixture to be adsorbed will not be too firmly bound. Usually an adsorbate adheres to any one adsorbent more firmly in a less polar solvent, consequently when, as frequently occurs, a single dense adsorption zone is obtained with light petroleum and develops only slowly when washed with this solvent, the development may be accelerated by passing to a more polar solvent. Numerous adsorbat are broken up by methyl alcohol, ethyl alcohol or acetone. It is not generally necessary to employ the pure alcohol the addition from 0 5 to 2 per cent, to the solvent actually used suffices in most cases. 

The solvent used to form the dope is evaporated during the extrusion process and must be recovered. This is usually done by adsorption on activated carbon or condensation by refrigeration. For final purification, the solvent is distilled. Approximately 3 kg of acetone, over 99%, is recovered per kg of acetate yam produced. Recovery of solvent from triacetate extmsion is similar, but ca 4 kg of methylene chloride solvent is needed per kg of triacetate yam extmded. 

Adsorption of lA of POMs with CV and Malachite Green (MG) on the polyurethane foams (PF) and some other adsorbents is investigated. While lA is fully adsorbed on the PF in wide pH range (0,4 M H SO - pH 4) extent of dye adsoi ption does not exceed 0,4%. lA are adsorbed faster then POMs. Extent of sorption of lA is 60-70% at 5 minutes and is complete after 15 minutes. lA can be eluted from PF most effectively by methylbutylketone, acetone or alcohols can be used too. 

Fig. 6. Breakthrough curves for aqueous acetone (10 mg 1" in feed) flowing through exnutshell granular active carbon, GAC, and PAN-based active carbon fibers, ACF, in a continuous flow reactor (see Fig. 5) at 10 ml min" and 293 K [64]. C/Cq is the outlet concentration relative to the feed concentration. Reprinted from Ind. Eng. Chem. Res., Volume 34, Lin, S. H. and Hsu, F. M., Liquid phase adsorption of organic compounds by granular activated carbon and activated carbon fibers, pp. 2110-2116, Copyright 1995, with permission from the American Chemical Society.

SO as to end the air mixture to adsorber No. 2. The system is then fully automatic. Solvents which have been successfully recovered by the activated carbon adsorption method include methanol, ethanol, butanol, chlorinated hydrocarbons including perchlorethylene, which boils at 121 C (250 °F), ethyl ether, isopropyl ether, the acetates up to amyl acetate, benzene, toluene, xylene, mineral spirits, naphtha, gasoline, acetone, methyl ethyl ketone, hexane, carbon disulfide, and others. 

Adsorption column chromatography has been employed to separate the constituents of pyrethrum. Florisil and aluminum oxide have been used as adsorption columns to retain much of the pigmented materials. The pyrethroids may be caused to elute with several solvents. In our experience mixtures of hexane with ethyl acetate, methanol, ethyl ether, dichloromethane, or acetone have provided different elution patterns. 

Co-adsorption experiments show a complex role of the nature and concentration of chemisorbed ammonia species. Ammonia is not only one of the reactants for the synthesis of acrylonitrile, but also reaction with Br()>nsted sites inhibits their reactivity. In particular, IR experiments show that two pathways of reaction are possible from chemisorbed propylene (i) to acetone via isopropoxylate intermediate or (ii) to acrolein via allyl alcoholate intermediate. The first reaction occurs preferentially at lower temperatures and in the presence of hydroxyl groups. When their reactivity is blocked by the faster reaction with ammonia, the second pathway of reaction becomes preferential. The first pathway of reaction is responsible for a degradative pathway, because acetone further transform to an acetate species with carbon chain breakage. Ammonia as NH4 reacts faster with acrylate species (formed by transformation of the acrolein intermediate) to give an acrylamide intermediate. At higher temperatures the amide may be transformed to acrylonitrile, but when Brreform ammonia and free, weakly bonded, acrylic acid. The latter easily decarboxylate forming carbon oxides. 

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