Thin-film distillation

Pressure distillation Simple and fractional distillation Flash distillation Thin-fUm distillation Thin-film distillation Molecular distillation... 

Vacuum drying Vacuum distillation Thin film evaporation Molecular distillation Sublimation Vacuum crystallisation Degassing and mixing Filtration... 

It is often advisable to lubricate ground-glass joint surfaces with an extremely thin film of vaseline. This applies particularly to joints employed in assemblies for distillation under reduced pressure. For distillations under greatly reduced pressures or at very high temperatures it is essential to employ a special lubricant, e.g., silicone grease. 

In order to make a multipurpose plant even more versatile than module IV, equipment for unit operations such as soHd materials handling, high temperature/high pressure reaction, fractional distillation (qv), Hquid—Hquid extraction (see Extraction, liquid-liquid), soHd—Hquid separation, thin-film evaporation (qv), dryiag (qv), size reduction (qv) of soHds, and adsorption (qv) and absorption (qv), maybe iastalled. 

Similar to IFP s Dimersol process, the Alphabutol process uses a Ziegler-Natta type soluble catalyst based on a titanium complex, with triethyl aluminum as a co-catalyst. This soluble catalyst system avoids the isomerization of 1-butene to 2-butene and thus eliminates the need for removing the isomers from the 1-butene. The process is composed of four sections reaction, co-catalyst injection, catalyst removal, and distillation. Reaction takes place at 50—55°C and 2.4—2.8 MPa (350—400 psig) for 5—6 h. The catalyst is continuously fed to the reactor ethylene conversion is about 80—85% per pass with a selectivity to 1-butene of 93%. The catalyst is removed by vaporizing Hquid withdrawn from the reactor in two steps classical exchanger and thin-film evaporator. The purity of the butene produced with this technology is 99.90%. IFP has Hcensed this technology in areas where there is no local supply of 1-butene from other sources, such as Saudi Arabia and the Far East. 

C-21 dicarboxyhc acids are produced by Westvaco Corporation in Charleston, South Carolina in multimillion kg quantities. The process involves reaction of tall oil fatty acids (TOFA) (containing about 50% oleic acid and 50% hnoleic acid) with acryhc acid [79-10-7] and iodine at 220—250°C for about 2 hours (90). A yield of C-21 as high as 42% was reported. The function of the iodine is apparendy to conjugate the double bond in linoleic acid, after which the acryhc acid adds via a Diels-Alder type reaction to form the cycHc reaction product. Other catalysts have been described and include clay (91), palladium, and sulfur dioxide (92). After the reaction is complete, the unreacted oleic acid is removed by distillation, and the cmde C-21 diacid can be further purified by thin film distillation or molecular distillation. 

Low-inventory distillation equipment, such as the thin film evaporator, are also available and should be considered for hazardous materials. This equipment offers the additional advantage of short residence time and is particularly useful for reactive or unstable materials. 

The removal of a large volume of solvent prior to distillation or crystallization is frequently necessary. If the solvent and product have similar boiling points (within 75"), careful fractional distillation of the entire solution is required. In other cases, the solvent may be removed by boiling on a steam bath, by rapid distillation at atmospheric pressure, or on a rotary evaporator. The rotary evaporator, used under aspirator pressure in conjunction with a heated water bath, allows rapid removal of most solvents boiling up to about 12071 atm (Fig. A3.12a). The presence of a thin film of liquid on the... 

For high vacuum distillation, Eckles et al. [150] suggest using a thin film or conventional batch process for industrial type installations however, there are many tray and packed colunms operating as low as 4 mm Hg, abs Eckles... 

The hydrolysis is performed as a continuous countercurrent reaction in tall reaction towers (height 15-20 m, diameter 0.7 m). The reaction time amounts to 60-90 min. Reaction products are as well obtained an aqueous glycerin solution (about 15%) as on a mixture of raw fatty acids [50]. The free fatty acids are carefully distilled with the aid of a thin film evaporator (2-10 mbar, 260°C maximum) [51]. Crystallization and transwetting are additional methods for fractionation of fatty acid mixtures. 

The raw product thus obtained is freed from solvent and water by vacuum distillation (7). The separation of the paraffin is performed under vacuum at temperatures above 220°C in a thin film evaporator (8) in the presence of overheated steam. The paraffin-containing solvent and the paraffin are recirculated to the process without further purification. 

Figure 1 shows the effects of the volume of decalin on the conversion of decalin on 3.9 wt. % Pt/C (0.3g) (a), 1 wt. % Pt/AlaOa (1.0 g) (b) and 1.46 wt. % Pt/A1(0H)0 (1.0 g) (C) at 483 K. Under those conditions, 0.0117, 0.010 and 0.0146 g of Pt were contained in the systems with Pt/C, Pt/AlaOs and Pt/A1(0H)0, respectively. The conversion of decalin on Pt/C showed to be a maximum at 1 ml of decalin (Fig.l (a)). This point is generally accepted as the liquid film state under reactive distillation conditions, at which the catalyst was just wet but not suspended at all through the dehydrogenation and covered with a thin film of liquid substrate. If such reactive distillation conditions are attained, the dehydrogenation proceeds more efficiently than liquid- and gas-phases [1]. 

Environmental tests have been combined with conventional electrochemical measurements by Smallen et al. [131] and by Novotny and Staud [132], The first electrochemical tests on CoCr thin-film alloys were published by Wang et al. [133]. Kobayashi et al. [134] reported electrochemical data coupled with surface analysis of anodically oxidized amorphous CoX alloys, with X = Ta, Nb, Ti or Zr. Brusic et al. [125] presented potentiodynamic polarization curves obtained on electroless CoP and sputtered Co, CoNi, CoTi, and CoCr in distilled water. The results indicate that the thin-film alloys behave similarly to the bulk materials [133], The protective film is less than 5 nm thick [127] and rich in a passivating metal oxide, such as chromium oxide [133, 134], Such an oxide forms preferentially if the Cr content in the alloy is, depending on the author, above 10% [130], 14% [131], 16% [127], or 17% [133], It is thought to stabilize the non-passivating cobalt oxides [123], Once covered by stable oxide, the alloy surface shows much higher corrosion potential and lower corrosion rate than Co, i.e. it shows more noble behavior [125]. 

If long distillation time is a problem, one can move to continuous distillation with conventional shell and tube heaters accompanied by a typical column bottom (often called a sump) which is a high temperature holdup, or better yet a short path evaporator (falling film, thin film, or wiped film) with usually a smaller receiver (called an accumulator in this case). The most chemical damage is in the thin liquid film at the heat transfer surface, so the short path evaporators do the least thermal damage. 

The third technique we used was a measurement of changes in the sorption behavior of a compound in the presence of humic materials. A thin film of OV-1, a methyl silicone gum used as a chromatographic stationary phase, was plated on the bottom of a 60 ml Hypo-Vial (Pierce Chemical Co., Rockford, 11.). A solution of radiolabeled pollutant was added to the vial in either buffered distilled water in a solution of humic materials. Again, it is assumed that the pollutant is solution consists of two fraction free and bound. It is also assumed... 

For Fourier transform infrared (FT-IR) measurement, thin films of polymers were cast from 0.5 wt% distilled-deionized water onto CaF2 plates at room temperature. Most of the water in the films was removed by evaporation at 50°C in a vacuum oven for 24 h. FT-IR spectra of the dried film were... 

A number of special vacuum distillation processes have been developed, whereby thermal decomposition of the oil is kept to a minimum. One of these employs thin film vaporization, in which mercury vapor is employed as an indirect heating medium (89, 71). Another employs a carrier other than steam—for example, kerosene—in the vaporization of the heavy lubricating oil fractions (16). These processes are being operated on a commercial scale, but apparently because of their special nature they have not been widely adopted by the petroleum industry. 

There are two useful tests for mercury purity which are easy to carry out. If base metals are present, the mercury will leave a thin film on a glass vessel. Secondly, if a small quantity of mercury is shaken in a stoppered flask with about three times its volume of pure distilled water, foaming will occur lasting for 5—15 s if it is pure. 

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