PRISM separators

A. Esterification of a-Cyano-0-Phenylacrylic Acid — In a 200-cc. round-bottom flask fitted with a reflux condenser, 50 g. of dry a-cyano-0-phenylacrylic acid (Org. Syn. 7, 20) is boiled for four and a half hours with 100 cc. of absolute alcohol containing 3-4 g. of anhydrous hydrogen chloride. The resulting solution is filtered rapidly while hot and allowed to stand overnight. Long, flat, colorless prisms separate which are filtered off with suction, washed with a little cold alcohol and dried in air. A further small quantity may be obtained by working up the mother liquor. The melting-point of the ethyl a-cyano-/3-phenylacrylate is 50° and the yield 46.5-53 g. (82-94 per cent of the theoretical amount). 

Monoterpenoid ketones, 24 536-541 Monoterpenoids, 24 468, 470, 472, 484-541 Monothiocarboxylic acids, 23 739 Monotropic phase transitions, 15 101 Monounsaturated fatty acids, 10 830 Monounsaturated olefins, hydrogenation of, 26 879-880 Monovinylacetylene, 1 230 Monsanto acetic acid process, 19 646 Monsanto adiponitrile process, 17 236 Monsanto aluminum chloride-based Alkylation process, 23 333 Monsanto Prism separator, 16 21 Monsanto process (Lummus-UOP Classic process), 16 74 23 339, 341 Monsanto-Washington University collaboration, 24 390, 400-401 Montanic acid... 

Figure 1. Analogy between total internal reflection and quantum tunneling (a) two glass prisms separated by an airgap (b) its quantum barrier analog. (From Nimtz and Heitmann [5].)...

Figure 7. The surface electromagnetic wave transmission between two prisms separated by 10 cm for (a) one monolayer of CugO on Cu and (b) five monolayers...

The vibrational spectrum of benzene around 1000 cnf has also been measured. IQ. Benzene was physisorbed on a cooled copper substrate in the vacuum chamber. Figure 19 shows the transmission for several thicknesses of benzene and a prism separation of 3 cm. The thickness was determined from the measured transmission in transparent regions using Eg. (7). The solid curves were calculated from Eqs. (5) and (6) using optical constants for benzene obtained from an ordinary transmission experiment.il The benzene film was assumed to be isotropic. Of the two absorption lines seen, one belongs to an in-plane vibrational mode, and one to an out-of-plane vibration. Since the electric field of the SEW is primarily perpendicular to the surface, the benzene molecules are clearly not all parallel or all perpendicular to the copper surface. Also it should be noted that the frequencies are the same (within the experimental resolution) as those of solid benzene22 and of nearly the same width. These features indicate that the benzene interacts only weakly with the copper surface, as would be expected for physisorbed molecules. 

In order for membranes to be used in a commercial separation system they must be packaged in a manner that supports the membrane and facilitates handling of the two product gas streams. These packages are generally referred to as elements or bundles. The most common types of membrane elements in use today include the spiral-wound, hollow fiber, tubular, and plate and frame configurations. The systems currently being marketed for gas separation are of the spiral-wound type, such as the SEPAREX and Delsep processes, and the hollow-fiber type such as the Prism separator and the Cynara Company process. 

Figure 4. A typical experimental configuration of surface electromagnetic wave propagation spectroscopy. A surface wave is launched along the surface of a metal using a coupling prism separated by an air gap. The light is coupled out to a detector through another prism.

In the Monsanto process (referred to as PRISM separators), the gas mixture flows around an array of hollow fibers, and only hydrogen and helium can diffuse into the fibers through the semi-permeable, polysulfone-coated walls. Separation from CH4, CO, O2 and N2 can be accomplished in this way46. The PRISM technology is now owned and marketed by Air Products. 

Monsanto and Ube (Japan) developed membrane processes for purification of hydrogen gas mixtures. This process is based on the selective diffusion of hydrogen through semi-permeable membranes in the form of hollow fibers. The Monsanto PRISM separator process (owned by Air Products as of 2004) uses a polysulfone fiber whereas Ube uses an aromatic polyimide fiber.46... 

Nickel Oithionate, NiS206.6H20, may be prepared by double decomposition of barium dithionate and nickel sulphate solutions.6 On concentration of the filtered solution, green triclinic prisms separate out. From its solution ammonia precipitates the hexammoniate, NiS206.6NH3. 

The purge gas is water scrubbed at 135 -145 bar, reducing the ammonia concentration to less than 200 ppm. The scrubbed purge gas is heated to 35 °C and sent directly to the Prism separators. Trace concentrations of ammonia and water vapor in the gas stream pose no problem to the membrane. Therefore, a dryer system is not required. 

The main advantages of the Prism separator system are simplicity, ease of operation, and low maintenance. Reference [962] compares membrane and cryogenic separation units for a large ammonia plant. 

I would like a preliminary estimate of the cost and performance of PriSm separators for the application described below... 

Lithium Tungstates.—The normal salt, solution when a suspension of tungstic anhydride in water is boiled with lithium carbonate, or when tungstic anhydride is added to fused lithium carbonate and the resulting mass extracted with water on evaporation, short, thick, oblique rhombic prisms separate, which readily dissolve in water yielding an alkaline solution. Lithium ditungstate is described by Anthon, but its existence is doubtfiil. 

Magnesium ditungstate, l g0.2 0g.SH20, was prepared by Lefort by heating a suspension of magnesium hydro.xide with excess of tungstic acid, and allowing the sohition formed to crystallise rhomboidal prisms separate, w hieli are readily soluble in water. 

Arsanthrene chloride in ten times its weight of warm nitric acid (density 1-38) is heated until no more nitrous fumes escape. An equal volume of water is then added and the product obtained recrystalliscd from hot dilute nitric acid (density 1 2). Large, ((olourless prisms separate (probably a dinitrate), which fall to a chalky imwdcr on washing with water. The acid does not melt at 3(i0 and is sparingly soluble in all solvents. 

Prisms and Gratings. Prisms and diffraction gratings are also widely used as monochromators. A prism separates... 

The KM hollow-fibers are employed in the PRISM separators of Monsanto (St. Louis, MO) which have been successfully tested since 1979 in more than 40 industrial plants in the chemical and refinery field. They are being used for the recovery of hydrogen from waste-gases and purge-streams that contain varying amounts of N, Ar, CO, CO2, to C paraffins, and C to Cg aromatics. 

FIGURE 20,2-3 Derailed flow, pressure, and composition diagram for the Prism separator system shown in Fig. 20.2-2. ... 

B. M. Bormaster. and D. C. Carter. "Increased Methanol Production Using Prism Separators,"... 

Monsalo Prism Separator Product Information Bullstsn, 1981. 

Between 1979 and 1985, forty-five PRISM separator recovery systems have been successfully implemented on ammonia purges around the world. As a result of hydrogen recovery, an incremental ammonia production of 3 to 5% can be achieved. Alternatively, at constant ammonia production energy savings amount to 0.6 to 0.9M BTU/ton ammonia. For a typical 1,150 ton/day plant, these improvements translate into 3M/year energy savings. 

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