Decomposition hydrogen sulfide

Hydrogen chloride released dissolves in water during condensation in the crude oil distillation column overhead or in the condenser, which cause corrosion of materials at these locations. The action of hydrochloric acid is favored and accelerated by the presence of hydrogen sulfide which results in the decomposition of sulfur-containing hydrocarbons this forces the refiner to inject a basic material like ammonia at the point where water condenses in the atmospheric distillation column. 

Chemical Properties. Although hydrogen sulfide is thermodynamically stable, it can dissociate at very high temperatures. The decomposition thermodynamics and kinetics have been reviewed and the equihbrium constant for the reaction has been deterrnined (101,102) ... 

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). 

Decomposition of Thiols. Thiols decompose by two principal paths (i43— i45). These are the carbon—sulfur bond homolysis and the unimolecular decomposition to alkene and hydrogen sulfide. For methanethiol, the only available route is homolysis, as in reaction 29. For ethanethiol, the favored route is formation of ethylene and hydrogen sulfide via the unimolecular process, as in reaction 30. 

Further hydrolysis of the carbon disulfide and the trithiocarbonate produces hydrogen sulfide, etc (33). In another study of the decomposition of sodium ethyl xanthate [140-90-9] in flotation solutions, eleven components of breakdown were studied. The dependence of concentration of those components vs time was examined by solving a set of differential equations (34). 

At room temperature bismuthine rapidly decomposes into its elements. The rate of decomposition increases markedly at higher temperatures (8). Bismuthine decomposes when bubbled through silver nitrate or alkafl solutions but is unaffected by light, hydrogen sulfide, or 4 sulfuric acid solution. There is no evidence for the formation of BiH, though the phenyl derivative, (C H BU, is known. The existence of BiH would not be anticipated on the basis of the trend found with other Group 15 (V) "onium" ions. 

The decomposition of (536) with hydrogen sulfide yields pyrazole (76T1909). The 1-phosphorylpyrazoles (537) are suitable reagents for the phosphorylation of alcohols, amines, hydrazines and azides (76AG(E)378). 

Corrosion products and deposits. All sulfate reducers produce metal sulfides as corrosion products. Sulfide usually lines pits or is entrapped in material just above the pit surface. When freshly corroded surfaces are exposed to hydrochloric acid, the rotten-egg odor of hydrogen sulfide is easily detected. Rapid, spontaneous decomposition of metal sulfides occurs after sample removal, as water vapor in the air adsorbs onto metal surfaces and reacts with the metal sulfide. The metal sulfides are slowly converted to hydrogen sulfide gas, eventually removing all traces of sulfide (Fig. 6.11). Therefore, only freshly corroded surfaces contain appreciable sulfide. More sensitive spot tests using sodium azide are often successful at detecting metal sulfides at very low concentrations on surfaces. 

Hydrogen sulfide is a commonly occurring decomposition product of organic matter. It is relatively water soluble at higher pHs where it is predominantly dissociated as and S ions. As the pH is decreased below 7, undissociated gas HjS begins to predominate and is released. Since its vapor density is > 1.0, HjS gas tends to settle in low places and creates a toxicity hazard. H S is readily oxidizable by a number of means to less toxic SO3" or 804 forms. 

Since aluminum is not attacked by hydrogen sulfide (HjS) solutions, it is used widely as a material in refineries for the handling of hydrocarbons made from sour crudes. In the strongly oxidizing conditions of manufacturing hydrogen peroxide, aluminum is one of the few materials that does not undergo decomposition. 

Ammonia, hydrogen sulfide, and sulfur dioxide may result from the decomposition of chemical treatments (although in large boiler plants, ammonia is often deliberately added to raise the boiler, steam, or condensate system pH). 

Sulfur forms several oxides that in atmospheric chemistry are referred to collectively as SOx (read sox ). The most important oxides and oxoacids of sulfur are the dioxide and trioxide and the corresponding sulfurous and sulfuric acids. Sulfur burns in air to form sulfur dioxide, S02 (11), a colorless, choking, poisonous gas (recall Fig. C.1). About 7 X 1010 kg of sulfur dioxide is produced annually from the decomposition of vegetation and from volcanic emissions. In addition, approximately 1 X 1011 kg of naturally occurring hydrogen sulfide is oxidized each year to the dioxide by atmospheric oxygen ... 

Since hydrogen sulfide and elemental sulfur occur together in hot underground deposits of natural gas (so-called sour gas ) the formation of sulfur-rich polysulfanes under these high-pressure conditions is very likely. If the gas is produced and in this context the pressure and temperature lowered, the decomposition reaction (Eq. 1) takes place and the precipitated sol-... 

The decomposition of tri- and tetrasulfane in CCI4 solution (0.2 mol 1 ) at 70 °C and in the absence of oxygen has been studied by H NMR spectroscopy [64]. Initially, tetrasulfane decomposes to a mixture of tri- and pentasul-fane but slowly and after an induction period hydrogen sulfide and disulfane are formed in addition. These results have been interpreted in terms of a radical-chain reaction. The initial step is assumed to be the homolytic cleavage of the central SS bond which has by far the lowest dissociation enthalpy of the molecule ... 

Hydrogen Sulfide Adsorption and Decomposition on the Clean and S-Covered Ft(lll) Surface... 

Oudar and co-workers studied the dissociative chemisorption of hydrogen sulfide at Cu(110) surfaces between 1968 and 1971.3,14 As in the case of Ni(110) described below, a series of structures were identified, which in order of increasing sulfur coverage were described as c(2 x 2), p(5 x 2) and p(3 x 2). In contrast to nickel, the formation of the latter phase is kinetically very slow from the decomposition of H2S and could only be produced at high temperatures and pressures. The c(2 x 2) and p(5 x 2) structures were confirmed by LEED,15 17 but the p(3 x 2) phase has not been observed by H2S adsorption since Oudar and colleagues work. 

An extraordinarily explosive solid, of which the sodium salt also explodes on heating to 260°C [1], An attempt to prepare the acid by treating its silver salt with hydrogen sulfide caused explosive decomposition. Contact with solid potassium hydroxide caused ignition [2],... 

Contact of hydrogen sulfide with dry or moist lead dioxide causes attainment of red heat and ignition. Contact of hydrogen trisulfide with the dioxide causes violent decomposition and ignition. 

---