Hydrogen sulfide pressure

Manufacture. Small cylinders of hydrogen sulfide are readily available for laboratory purposes, but the gas can also be easily synthesized by action of dilute sulfuric or hydrochloric acid on iron sulfide, calcium sulfide [20548-54-3], zinc sulfide [1314-98-3], or sodium hydrosulfide [16721 -80-5]. The reaction usually is mn in a Kipp generator, which regulates the addition of the acid to maintain a steady hydrogen sulfide pressure. Small laboratory quantities of hydrogen sulfide can be easily formed by heating at 280—320°C a mixture of sulfur and a hydrogen-rich, nonvolatile aUphatic substance, eg, paraffin. Gas evolution proceeds more smoothly if asbestos or diatomaceous earth is also present. 

Figure I also shows the hydrogen sulfide pressure profile in the case of countercurrent operation. It can be seen that the main part of the bed where high catalyst activity is needed now operates under H2S-lean conditions. Only a relatively small part of the bed operates under H2S-rich conditions, and in this part suppression of catalytic activity is less serious, since here the conversion of relatively reactive compounds takes place. Therefore, the countercurrent mode of operation will be clearly superior, and this is the more true the deeper the desulfurization target.

Iron ui. iy he removed hy the hydrogen sulfide pressure bottle, precipitation, httl a nureli more, convenient method is to oxidize the iron In die ferric condition, thou pour the solution into a hoi 10 per rent sxluluin of sodium hydroxide. Boil for u time, cool, filter, and wash the ferric hydroxide thoroughly. If much iron is prcsenl the precipitate should he dissolved II acid and the precipitation repeated. Iron may he successfully removed hy I wo or more precipitations with ammonia. 

In the acid-leaching process, the oxide ore is leached with sulfuric acid at elevated temperature and pressure, which causes nickel, but not iron, to enter into solution. The leach solution is purified, foHowed by reaction with hydrogen sulfide and subsequent precipitation of nickel and cobalt sulfides. 

Gas purification processes fall into three categories the removal of gaseous impurities, the removal of particulate impurities, and ultrafine cleaning. The extra expense of the last process is only justified by the nature of the subsequent operations or the need to produce a pure gas stream. Because there are many variables in gas treating, several factors must be considered (/) the types and concentrations of contaminants in the gas (2) the degree of contaminant removal desired (J) the selectivity of acid gas removal required (4) the temperature, pressure, volume, and composition of the gas to be processed (5) the carbon dioxide-to-hydrogen sulfide ratio in the gas and (6) the desirabiUty of sulfur recovery on account of process economics or environmental issues. 

Reactions with Sulfur Compounds. Thiosuccinic anhydride [3194-60-3] is obtained by reaction of diethyl or diphenyl succinate [621-14-7] with potassium hydrogen sulfide followed by acidification (eq. 10). Thiosuccinic anhydride is also obtained from succinic anhydride and hydrogen sulfide under pressure (121). 

Because of its low dielectric constant, Hquid hydrogen sulfide is a poor solvent for ionic salts, eg, NaCl, but it does dissolve appreciable quantities of anhydrous AlCl, ZnCl2, FeCl, PCl, SiCl, and SO2. Liquid hydrogen sulfide or hydrogen sulfide-containing gases under pressure dissolve sulfur. At equihbrium H2S pressure, the solubihty of sulfur in Hquid H2S at —45, 0, and 40°C is 0.261, 0.566, and 0.920 wt %, respectively (98). The equiHbria among H2S, H2S, and sulfur have been studied (99,100). 

The practical importance of the higher sulfanes relates to their formation in sour-gas wells from sulfur and hydrogen sulfide under pressure and their subsequent decomposition which causes well plugging (134). The formation of high sulfanes in the recovery of sulfur by the Claus process also may lead to persistance of traces of hydrogen sulfide in the sulfur thus produced (100). Quantitative deteanination of H2S and H2S in Claus process sulfur requires the use of a catalyst, eg, PbS, to accelerate the breakdown of H2S (135). 

Sulfurization of unsaturated compounds and meicaptans is normally carried out at atmospheric pressure, in a mild or stainless steel, batch-reaction vessel equipped with an overhead condenser, nitrogen atmosphere, an agitator, heating media capable of 120—215°C temperatures and a scmbber (typically caustic bleach or diethanolamine) capable of handling hydrogen sulfide. If the reaction iavolves the use of H2S as a reactant or the olefin or mercaptan is a low boiling material, a stainless steel pressurized vessel is recommended. 

Molecular sieves are typically regenerated using a sHp stream of the treated gas at elevated temperature and reduced pressure. This regeneration step creates an enriched hydrogen sulfide stream which must then be further treated if the sulfur is to be recovered. A typical molecular sieve adsorption unit is shown schematically in Figure 2. 

Cold methanol has proven to be an effective solvent for acid gas removal. Cold methanol is nonselective in terms of hydrogen sulfide and carbon dioxide. The carbon dioxide is released from solution easily by reduction in pressure. Steam heating is required to release the hydrogen sulfide. A cold methanol process is Hcensed by Lurgi as Rectisol and by the Institute Francaise du Petrole (IFP) as IFPEXOL. 

SolubiHty of carbon dioxide in ethanolamines is affected by temperature, amine solution strength, and carbon dioxide partial pressure. Information on the performance of amines is available in the Hterature and from amine manufacturers. Values for the solubiHty of carbon dioxide and hydrogen sulfide mixtures in monoethanolamine and for the solubiHty of carbon dioxide in diethanolamine are given (36,37). SolubiHty of carbon dioxide in monoethanolamine is provided (38). The effects of catalysts have been studied to improve the activity of amines and provide absorption data for carbon dioxide in both mono- and diethanolamine solutions with and without sodium arsenite as a catalyst (39). Absorption kinetics over a range of contact times for carbon dioxide in monoethanolamine have also been investigated (40). 

In the dual-temperature H2O/H2S process (61,62), exchange of deuterium between H20(l) and H2S(g) is carried out at pressures of ca 2 MPa (20 atm). At elevated temperatures deuterium tends to displace hydrogen in the hydrogen sulfide and thus concentrates in the gas. At lower temperatures the driving force is reversed and the deuterium concentrates in H2S in contact with water on the tiquid phase. 

Figure 14-12 illustrates the influence of system composition and degree of reaetant eonversion upon the numerical values of for the absorption of CO9 into sodium hydroxide solutions at constant conditions of temperature, pressure, and type of packing. An excellent experimental study of the influence of operating variables upon overall values is that of Field et al. (Pilot-Plant Studie.s of the Hot Carbonate Proce.s.s for Removing Carbon Dioxide and Hydrogen Sulfide, U.S. Bureau of Mines Bulletin 597, 1962). 

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