Distillation high pressure

Acid Color 1963 Gardtwr, Short-Path Methyl Ester Distillation High Pressure Liquid Chromatography ... 

Separation of low-molecular-weight materials. Low-molecular-weight materials are distilled at high pressure to increase their condensing temperature and to allow, if possible, the use of cooling water or air cooling in the column condenser. Very low... 

The necessity of carrying out injection at high pressure and the atomization into fine droplets using an injector imposes very precise volatility characteristics for the diesel fuel. French and European specifications have established two criteria for minimum and maximum volatility therefore, the distilled fraction in volume % should be ... 

Reppe s work also resulted in the high pressure route which was estabUshed by BASF at Ludwigshafen in 1956. In this process, acetylene, carbon monoxide, water, and a nickel catalyst react at about 200°C and 13.9 MPa (2016 psi) to give acryUc acid. Safety problems caused by handling of acetylene are alleviated by the use of tetrahydrofuran as an inert solvent. In this process, the catalyst is a mixture of nickel bromide with a cupric bromide promotor. The hquid reactor effluent is degassed and extracted. The acryUc acid is obtained by distillation of the extract and subsequendy esterified to the desked acryhc ester. The BASF process gives acryhc acid, whereas the Rohm and Haas process provides the esters dkecdy. 

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. 

Concentration of Rare Gas Crudes. The distillation of air is classically carried out in the double-column and auxihary equipment of Figure 5. Dry, C02-free air, chilled to partial liquefaction by heat exchange, is introduced into the lower nitrogen or high pressure column. This unit is typically... 

Ma.nufa.cture. Nickel carbonyl can be prepared by the direct combination of carbon monoxide and metallic nickel (77). The presence of sulfur, the surface area, and the surface activity of the nickel affect the formation of nickel carbonyl (78). The thermodynamics of formation and reaction are documented (79). Two commercial processes are used for large-scale production (80). An atmospheric method, whereby carbon monoxide is passed over nickel sulfide and freshly reduced nickel metal, is used in the United Kingdom to produce pure nickel carbonyl (81). The second method, used in Canada, involves high pressure CO in the formation of iron and nickel carbonyls the two are separated by distillation (81). Very high pressure CO is required for the formation of cobalt carbonyl and a method has been described where the mixed carbonyls are scmbbed with ammonia or an amine and the cobalt is extracted as the ammine carbonyl (82). A discontinued commercial process in the United States involved the reaction of carbon monoxide with nickel sulfate solution. 

Semiconductors. Phosphine is commonly used in the electronics industry as an -type dopant for siUcon semiconductors (6), and to a lesser extent for the preparation of gaUium—indium—phosphide devices (7). For these end uses, high purity, electronic-grade phosphine is required normally >99.999% pure. The main impurities that occur in phosphine manufactured by the acid process are nitrogen [7727-37-9] hydrogen [1333-74-0] arsine [7784-42-17, carbon dioxide [124-38-9], oxygen [7782-44-7], methane [74-82-8], carbon monoxide [630-08-0], and water [7732-42-1]. Phosphine is purified by distillation under pressure to reduce the level of these compounds to <1 ppm by volume. The final product is sold as CYPURE (Cytec Canada Inc.) phosphine. 

Analytical Techniques. Sorbic acid and potassium sorbate are assayed titrimetricaHy (51). The quantitative analysis of sorbic acid in food or beverages, which may require solvent extraction or steam distillation (52,53), employs various techniques. The two classical methods are both spectrophotometric (54—56). In the ultraviolet method, the prepared sample is acidified and the sorbic acid is measured at 250 260 nm. In the colorimetric method, the sorbic acid in the prepared sample is oxidized and then reacts with thiobarbituric acid the complex is measured at - 530 nm. Chromatographic techniques are also used for the analysis of sorbic acid. High pressure Hquid chromatography with ultraviolet detection is used to separate and quantify sorbic acid from other ultraviolet-absorbing species (57—59). Sorbic acid in food extracts is deterrnined by gas chromatography with flame ionization detection (60—62). 

Tar. Before the development of gas chromatography (gc) and high pressure Hquid chromatography (hplc), the quantitative analyses of tar distillate oils involved tedious high efficiency fractionation and refractionation, followed by identification or estimation of individual components by ir or uv spectroscopy. In the 1990s, the main components of the distillate fractions of coal tars are deterrnined by gc and hplc (54). The analytical procedures included in the specifications for tar bulk products are given in the relevant Standardi2ation of Tar Products Tests Committee (STPTC) (33), ISO (55), and ASTM (35) standards. 

Pure zirconium tetrachloride is obtained by the fractional distillation of the anhydrous tetrachlorides in a high pressure system (58). Commercial operation of the fractional distillation process in a batch mode was proposed by Ishizuka Research Institute (59). The mixed tetrachlorides are heated above 437°C, the triple point of zirconium tetrachloride. AH of the hafnium tetrachloride and some of the zirconium tetrachloride are distiUed, leaving pure zirconium tetrachloride. The innovative aspect of this operation is the use of a double-sheU reactor. The autogenous pressure of 3—4.5 MPa (30—45 atm) inside the heated reactor is balanced by the nitrogen pressure contained in the cold outer reactor (60). However, previous evaluation in the former USSR of the binary distiUation process (61) has cast doubt on the feasibHity of also producing zirconium-free hafnium tetrachloride by this method because of the limited range of operating temperature imposed by the smaH difference in temperature between the triple point, 433°C, and critical temperature, 453°C, a hafnium tetrachloride. 

Reverse Osmosis. A reverse osmosis (RO) process has been developed to remove alcohol from distilled spirits without affecting the sensory properties (14). It consists of passing barrel-strength whiskey through a permeable membrane at high pressure, causing the alcohol to permeate the membrane and concentrating the flavor components in the retentate. 

The analysis of individual chemical constituents in distilled spirits currently is performed using gas chromatography (gc) and high pressure Hquid chromatography (hplc). Although other types of instmmental analyses have yielded much information regarding the chemical constituency of distilled spirits, the combination of gc and hplc has allowed hundreds of different chemical components of distilled spirits to be individually identified and accurately quantified. 

There are essentially four steps or unit operations in the manufacture of fatty acids from natural fats and oils (/) batch alkaline hydrolysis or continuous high pressure hydrolysis (2) separation of the fatty acids usually by a continuous solvent crystallisation process or by the hydrophilisation process (J) hydrogenation, which converts unsaturated fatty acids to saturated fatty acids and (4) distillation, which separates components by their boiling points or vapor pressures. A good review of the production of fatty acids has been given (1). 

Perhydrodlpyrldlno(l,2-a][l, 2 -c]-pyrlmldlne (2). (a) To an ice-cooled solution of 2-(2-(pipendyl)ethyll pipendine 1 (3.2 g, 10 2 mmol) in EtaO (200 mL) was added N-chlorosuccinimlde (NCS) (1.7 g, 12 7 mmol) Under stirring, the reaction mixture was inadated with a 300 W high pressure mercury lamp under N2 for 5 h. The precipitate was filtered, dryed and extracted with n-pentane Evaporation of the solvent and distillation gave 1.0 g of 2 (50%). bp 140 C (20 torr)... 

If the pump is a filter pump off a high-pressure water supply, its performance will be limited by the temperature of the water because the vapour pressure of water at 10°, 15°, 20° and 25° is 9.2, 12.8, 17.5 and 23.8 mm Hg respectively. The pressure can be measured with an ordinary manometer. For vacuums in the range lO" mm Hg to 10 mm Hg, rotary mechanical pumps (oil pumps) are used and the pressure can be measured with a Vacustat McLeod type gauge. If still higher vacuums are required, for example for high vacuum sublimations, a mercury diffusion pump is suitable. Such a pump can provide a vacuum up to 10" mm Hg. For better efficiencies, the pump can be backed up by a mechanical pump. In all cases, the mercury pump is connected to the distillation apparatus through several traps to remove mercury vapours. These traps may operate by chemical action, for example the use of sodium hydroxide pellets to react with acids, or by condensation, in which case empty tubes cooled in solid carbon dioxide-ethanol or liquid nitrogen (contained in wide-mouthed Dewar flasks) are used. 

Polymerization of raw feedstock. Aliphatic hydrocarbon resins. Raw feedstock contains straight-chain and cyclic molecules and mono- and diolefins. The most common initiator in the polymerization reaction is AICI3/HCI in xylene. The resinification consists of a two-stage polymerization in a reactor at 45°C and high pressure (10 MPa) for several hours. The resulting solution is treated with water and passed to distillation to obtain the aliphatic hydrocarbon resins. Several aliphatic hydrocarbon resins with different softening points can be adjusted. 

The Ryan-Holmes distillation process uses cryogenic distillation to remove acid gases from a gas stream. This process is applied to remove COi for LPG separation or where it is desired to produce COt at high pressure for reservoir injection. This complicated process is beyond the scope of this book. 

---