Carbon dioxide crystallization

Analysis of an incident (Van Wees 1989) involving a carbon dioxide storage vessel suggests that carbon dioxide can evaporate explosively even when its temperature is below T. This may occur because carbon dioxide crystallizes at ambient pressure, thus presenting enough nucleation sites for liquid to flash. 

Figures 6.30 and 6.31 present the same information for saturated hydrocarbons. In Figure 6.30, the saturated liquid state is on the lower part of the curve and in Figure 6.31 it is on the upper part of the curve. Below T y, the line width changes, indicating that the liquid probably does not flash below that level. Note that a line has been drawn only to show the relationship between the points a curve reflecting an actual event would be smooth. Note that a liquid has much more energy per unit of volume than a vapor, especially carbon dioxide. Note It is likely that carbon dioxide can flash explosively at a temperature below the superheat limit temperature. This may result from the fact that carbon dioxide crystallizes at ambient pressure and thus provides the required number of nucleation sites to permit explosive vaporization.

Carbon dioxide (Dry Ice) consists of CO molecules. I hese molecules are linear, with the carbon atom in the center. Make three drawings, repre sen ting your concepts of carbon dioxide gas, carbon dioxide liquid, and carbon dioxide crystal. 

Fast local-MP2 method with density-fitting for crystals. II. Test calculations and application to the carbon dioxide crystal " ... 

The carbon atoms in a carbon dioxide crystal form a face-centered cubic lattice, which is composed of four simple cubic lattices. On each simple cubic lattice the COg molecules extend in the same direction towards the body diagonals, the direction being different on different simple lattices (cf. Fig. 10). The distance between nearest-neighbor carbon atoms will again be denoted by d. 

This process, which was described by Hise et al. in 1982, has apparently not been applied commercially. It is mentioned here because of the unusual concepts incorporated into the flow scheme. These include the use of crystallization of one component (carbon dioxide) as a means of stripping another component (hydrogen sulfide) from solution, and the use of a slurry of carbon dioxide crystals in an organic solvent to condense and absorb additional carbon dioxide. The process was a joint development of CNG Research Corporation, the U.S. Elepartment of Energy, and Helipump Corporation. It was proposed for use in the removal of acid gas from coal-derived gas streams at pressures above 300 psig. 

Prepare a mixture of 30 ml, of aniline, 8 g. of o-chloro-benzoic acid, 8 g. of anhydrous potassium carbonate and 0 4 g. of copper oxide in a 500 ml. round-bottomed flask fitted with an air-condenser, and then boil the mixture under reflux for 1 5 hours the mixture tends to foam during the earlier part of the heating owing to the evolution of carbon dioxide, and hence the large flask is used. When the heating has been completed, fit the flask with a steam-distillation head, and stcam-distil the crude product until all the excess of aniline has been removed. The residual solution now contains the potassium. V-phenylanthrani-late add ca. 2 g. of animal charcoal to this solution, boil for about 5 minutes, and filter hot. Add dilute hydrochloric acid (1 1 by volume) to the filtrate until no further precipitation occurs, and then cool in ice-water with stirring. Filter otT the. V-phcnylanthranilic acid at the pump, wash with water, drain and dry. Yield, 9-9 5 g. I he acid may be recrystallised from aqueous ethanol, or methylated spirit, with addition of charcoal if necessary, and is obtained as colourless crystals, m.p. 185-186°. 

By cooling the solution in a freezing mixture (ice and salt, ice and calcium chloride, or solid carbon dioxide and ether). It must be borne in mind that the rate of crystal formation is inversely proportional to the temperature cooling to very low temperatures may render the mass... 

By adding a few lumps of solid carbon dioxide this produces a number of cold spots here and there, and assists the formation of crystals. 

Dissolve 57 g. of dry malonic acid in 92 5 ml. of dry P3rridine contained in a 500 ml. round-bottomed flask, cool the solution in ice, and add 57 g. (70 ml.) of freshly distilled n-heptaldehyde (oenanthol) with stirring or vigorous shaking. After a part of the aldehyde has been added, the mixture rapidly seta to a mass of crystals. Insert a cotton wool (or calcium chloride) tube into the mouth of the flask and allow the mixture to stand at room temperature for 60 hours with frequent shaking. Finally, warm the mixture on a water bath until the evolution of carbon dioxide ceases (about 8 hours) and then pour into an equal volume of water. Separate the oily layer and shake it with 150 ml. of 25 per cent hydrochloric acid to remove pyridine. Dissolve the product in benzene, wash with water, dry with anhydrous magnesium sulphate, and distil under reduced pressure. Collect the ap-nonenoic acid at 130-13272 mm. The yield is 62 g. 

Sodium salt of eosin. Grind together in a mortar 12 g. of eosin with 2 g. of anhydrous sodium carbonate. Transfer the mixture to a 250 ml. conical flask, moisten it with 10 ml. of rectified spirit, add 10 ml. of water and warm on a water bath, with stirring, until the evolution of carbon dioxide ceases. Add 50 ml. of ethyl alcohol, heat to boiling, and filter the hot solution through a fluted filter paper (supported in a short-stemmed funnel) into a beaker, and allow to stand overnight. Filter ofiF the browiiish-red crystals of sodium eosin, wash with a little alcohol, and dry. The yield is 10 g. 

Indane-1 3-dione (1 3-diketohydrindene). Method A. To a solution of sodium methoxide, prepared from 6 1 g. of sodium and 200 ml. of anhydrous methanol, add 15 g. of phthalylacetic acid and allow to stand for 1 hour at room temperature collect the yellow precipitate by suction filtration. Mix the yellow solid with 150 ml. of 10 per cent, sulphuric acid, heat on a steam bath until no more carbon dioxide is evolved (15-20 minutes), filter the hot solution and allow to cool. Collect the yellow crystals by filtration at the pump, wash with a httle water and dry at 100°. The yield of crude 1 3-indanedione, m.p. 125-126°, is 7 g. RecrystaUise from hght petroleum, b.p. 80-100°, and thus obtain the pure product, m.p. 129-130°. 

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