Ammonia separation

The removal of ammonia product is accomplished via mechanical refrigeration or absorption / distillation. The choice is made by examining the fixed and operating costs. Typically, refrigeration is more economical at synthesis pressures of 100 atmospheres (1470 psia) or greater. At lower pressures, absorption/distillation is usually favored. The two methods are compared in Table 6.5212. 

High Energy Costs at Lower Loop Pressures (Below 100 Atmospheres) 

Higher Fixed Costs at Pressures Below 100 Atmospheres 

Almost constant energy costs that are independent of pressure. Less condensation separation below a pressure of 100 atmosphere. 

Almost constant fixed costs at a range of pressures. Less condensation separation at pressures below 100 atmospheres. 

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Iron, cobalt, and nickel catalyze this reaction. The rate depends on temperature and sodium concentration. At —33.5°C, 0.251 kg sodium is soluble in 1 kg ammonia. Concentrated solutions of sodium in ammonia separate into two Hquid phases when cooled below the consolute temperature of —41.6°C. The compositions of the phases depend on the temperature. At the peak of the conjugate solutions curve, the composition is 4.15 atom % sodium. The density decreases with increasing concentration of sodium. Thus, in the two-phase region the dilute bottom phase, low in sodium concentration, has a deep-blue color the light top phase, high in sodium concentration, has a metallic bronze appearance (9—13). 

Krishnamurty and Wahl tried a number of separation methods and eventually used a modified dipyridyl-ammonia separation to obtain kinetic data for this exchange. The zero-time exchange lay between 25 and 50 %, depending on the conditions the activity of the V(dipy)3 ion was measured. The rate law obtained for perchlorate media was... 

An explosion rupturing an ammonia separator (still) in an ammonia production unit, probably because mercury vapour from geological sources entered with hydrogen syngas originating from natural gas and reacted to give explosive nitride deposits. The separator remains crackled when scraped [1]. For a more academic study of the effects of mercury on ammonia plants, including embrittlement and corrosion, as well as explosive deposits [2],... 

A large amount of trimethylacetic acid and a small amount of at least one C9-acid and one Ci3-acid are formed from the /-butyl alcohol. The treatment with ammonia separates 1-ada-mantanecarboxylic acid from these acids, the ammonium salts of which remain in solution. 

According to M. Ascoli,9 liquid ammonia shows the phenomenon of electrosmose. When a difference of potential is established between two portions of liquid ammonia separated by a porous septum of calcined alumina, and kept at a temp, of —60° by immersion in a bath of acetone cooled with solid carbon dioxide, there is usually a slight displacement of the liquid in the opposite direction to the current but if the liquid is coloured blue by the formation of a small quantity of sodammoniuin in soln. there is a marked displacement of the liquid in the same direction as the current, showing that the introduction of the sodium has caused the liquid to become positively and the alumina negatively electrified. 

Suspend, in a reactor, 10 kg of 2-ethoxycarbonylindoline obtained previously in 110 liters of hydrochloric ethanol. Next, add 20 kg of granulated tin. Keep stirring for approximately 2 days at room temperature. Evaporate off the ethanol, take up the residue with water and add 110 liters of toluene. Stir for approximately 20 min. Alkalify with aqueous ammonia. Separate off the aqueous phase and extract once again with 150 liters of toluene. Combine the toluene phases and wash them with water. Separate off the toluene phases, filter. Remove the water by distilling the water-toluene azeotrope. Cool and pass through a stream of anhydrous HCI gas. Cool. Evaporate down and wash with pure toluene. Weight obtained of (R,S)-2-ethoxycarbonylindoline 10.11 kg. Yield 84%. 

In the absence of ammonia, separation of the mixture of hydrocarbons was negligible. Table IV summarizes the data for pure solvents and shows a comparison with some selected data for ammonia /pure gas mixtures. Ammonia/ethylene mixtures appear to be more effective as solvent mixtures, with a marked separation of butene achieved. 2,3-Butadiene is concentrated in the heavy phase, in agreement with the findings reported for liquid ammonia (1). 

The initial synthetic approach to conivaptan HCl (1) employed by the Yamanouchi discovery group26 commenced with commercially available benzazepinone 10. Acylation of 10 with p-nitrobenzoyl chloride provided benzamide 11. Subsequent hydrogenation of 11 over palladium on carbon yielded aniline 12, which was in turn condensed with biphenyl-2-carbonyl chloride to provide bis(amide) 13. Bis(amide) 13 was subsequently heated with copper(II) bromide in boiling chloroform/ethyl acetate to furnish a-bromoketone 14. It is interesting that condensation of a-bromoketone 14 with acetamidine hydrochloride in the presence of potassium carbonate in boiling acetonitrile afforded not only the desired imidazobenzazepine product (1 53% yield, 2 steps) but also the related oxazolobenzazepine 15 (7% yield, 2 steps), which presumably resulted from nucleophilic attack of the benzazepinone oxygen on the amidine moiety followed by loss of ammonia. Separation of oxazolobenzazepine byproduct 15 from imidazobenzazepine 1 by silica gel chromatography followed by treatment of the purified imidazobenzazepine free-base with hydrochloric acid then provided conivaptan HCl (1). 

In all commercial plants ammonia is recovered from the synthesis loop by cooling the synthesis gas to condense the ammonia under synthesis pressure. The liquid ammonia product is separated from the gas, which is recycled. Arrangement and location of the ammonia separator(s), recirculation compression, addition of makeup gas and extraction of purge gas are discussed in Section 4.5.1 (see also Figure 77). 

Separator temperature together with pressure and location of make-up gas addition, the temperature of the ammonia separator determines the ammonia concentration at the converter inlet. A lower temperature means lower ammonia concentration, which translates into either a lower catalyst volume or a higher conversion. 

Methanator m) C02 removal solvent boiler n) Process condensate separator o) C02 absorber p) Synthesis gas compressor q) Process air compressor r) Ammonia converter s) High-pressure ammonia separator 1) Ammonia and hydrogen recovery from purge and flash gas... 

The separation of the ammonia formed from the circulating gas is mainly carried out by condensation at low temperatures, water cooling being augmented by the evaporation of liquid ammonia. The evaporated ammonia is either utilized as an intermediate or is liquefied by compression and subsequent cooling. In the case of low synthesis pressures and a demand for aqueous ammonia, separation of ammonia formed in the synthesis gas is carried out by absorption in water. Water vapor which thereby enters the cycling gas is removed by scrubbing with liquid ammonia, to avoid deterioration of the catalyst by water vapor. 

The fresh feed composed of 75.16% H2, 24.57% N2, and 0.27% Ar is mixed with the recycled gas and enters the reactor with a composition of 79.52% H2. The gas leaving the ammonia separator contains 80.01% H2 and no ammonia. The product ammonia contains no dissolved gases. Per 100 moles of fresh feed ... 

A.N. Volkova, A.A. Malygin, S.I. Koltsov, V.B. Aleskovskii, Method of Ammonia Separating from Gaseous Mixtures, USSR Patent No. 356242 (1972). 

Castor-oil Oleum ncini (6 6., Br.)—is usually obtained by expression of the seeds, although in some countries it is prepared by decoction or by extraction with alcohol. It is a thick, viscid, yellowish oil, has a faint odor and a nauseous taste. It is more soluble in alcohol than any other fixed vegetable oU, and ia also very soluble in ether. It saponifies very readily. Ammonia separates from it a ciystalline solid, fusible at 6fl (158 8 F.) rictso/aim de. Hot HNO, attacks it energetic y, and finally converts it into suberic ctcid. 

SO2 from the sulfuric acid plant Double contact acid plant, Ammonia-separator, High-speed catalyst Valuable byproduct (add). Ammonium sulfate as byproduct... 

Dissolve the sulphate of iron and the carbonate of ammonia separately in half a gallon of the water, and mix the two solutions with brisk stirring in a deep cylindrical vessel, which is then to be covered as accurately as possible. Set the mixture by for twenty-four hours, and from the precipitate (carbonate of iron) which has subsided separate the supernatant liquid by a siphon. Pour on the remainder of the water, stir well, and after subsidence again remove the clear liquid. Collect the resulting carbonate on a calico filter, and, having first subjected it to expression, rub it with the sugar in a porcelain mortar. Finally, dry the mixture at a temperature not exceeding 212 F. 

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