Sulphur compounds treatment

The collection of representative reservoir fluid samples is important in order to establish the PVT properties - phase envelope, bubble point, Rg, B, and the physical properties - composition, density, viscosity. These values are used to determine the initial volumes of fluid in place in stock tank volumes, the flow properties of the fluid both in the reservoir and through the surface facilities, and to identify any components which may require special treatment, such as sulphur compounds. 

By treatment with anhydrous aluminium chloride (Holmes and Beeman, 1934). Ordinary commercial, water-white benzene contains about 0 05 per cent, of thiophene. It is first dried with anhydrous calcium chloride. One litre of the dry crude benzene is shaken vigorously (preferably in a mechanical shaking machine) with 12 g. of anhydrous aluminium chloride for half an hour the temperature should preferably be 25-35°. The benzene is then decanted from the red liquid formed, washed with 10 per cent, sodium hydroxide solution (to remove soluble sulphur compounds), then with water, and finally dried over anhydrous calcium chloride. It is then distilled and the fraction, b.p. 79-5-80-5°, is collected. The latter is again vigorously shaken with 24 g. of anhydrous aluminium chloride for 30 minutes, decanted from the red liquid, washed with 10 per cent, sodium hydroxide solution, water, dried, and distilled. The resulting benzene is free from thiophene. 

Anaerobic treatment. Anaerobic processes can convert organic sulphur compounds and sulphate into sulphides... 

LNG is simple to re-gasify in order to deliver almost pure methane at the end users. In contrast to natural gas that contains typically around 90% methane, and some ethane, propane and heavier hydrocarbons, the liquefaction process involves pre-treatment of the gas in order to remove carbon dioxide, sulphur compounds, water, and petroleum gases with carbon number higher than one (butane, propane etc.). This is done in order to avoid formation of solids in the cold heat exchangers. The presence of nitrogen is usually limited at about 1% (refer Table 2 on page 81). 

Sulphur compounds are reduced to sulphide by this treatment the residue may be moistened with water and placed in contact with a silver coin when a brown to black stain of silver sulphide is obtained (Hepar reaction), or it may be extracted with a little water and filtered into a freshly prepared sodium nitroprusside solution, when an unstable purple colouration will indicate the presence of sulphur (see Section IV.6, reaction 5) (Table V.5). 

Fig. 10.6 Influence of treatments with copper sulphate on the amount of sulphur compounds found...

In addition, in most methane-containing emissions (emissions from coke ovens, composting plants, etc.), sulphur compounds (SO2, H2S or organosulphur compounds) are present. The presence of these compounds hinders most the treatments. So, in the case of... 

Depending on the purity of the gas feedstock, there may be pre-treatment of natural gas to remove impurities such as sulphur compounds that will poison catalysts used in subsequent processes. There are three common technologies in use to convert natural gas into syngas steam methane reforming (SMR), partial oxidation (POX) and auto-thermal reforming (ATR). 

Phosphorus Compounds.—Treatment of the dioxaphospholen (635) with sulphur yields a mixture of the oxathiole (636) and fran -dibenzoylstilbene, PhCOCPh=CPhCOPh." 2-Phenyl-l,3,2-dioxaphospholan (637 R = Ph) dimerizes in solution to a ten-membered-ring compound, which was isolated as (638) by sulphurization." The cyclic thiophosphorous acid (639) exists in equilibrium with the betaine (640) in aqueous ethanol/ The spiro-compound (641), which contains a phosphorus-hydrogen bond, is formed by the action of (637 R = Cl) on diethyl tartrate. The phosphazene (642) spontaneously cyclizes to the spiro-compound (643). " Stable derivatives (645) and (646 R = Br) of five-co-ordinate phosphorus have been obtained by the action of bromine on the o-phenylene phosphite (644)/ The chlorine analogue (646 R Cl) reacts with 3,5-dimethylpyrazole to give the corresponding pyrazole derivative (646 R = 3,5-dimethylpyrazol-l-yl), which reversibly dimerizes to the zwitterion (647). ... 

Sulphur-containing constituents of hop oil [85], although only present in trace amounts, are potent flavouring agents (Table 13.7). They can be distinguished by gas chromatography using a flame photometric detector. Many hops are treated in the field with elemental sulphur to control mildew and the level of such treatment can affect the level of sulphur compounds in the oil... 

Hop oil contains a series of thioesters (Table 13.7) the combined amount of which in steam-distilled hop oil usually exceeds 1000 ppm. The level of thioesters in the oil does not appear to be affected either by treatment of hops with elemental sulphur on the bine or by sulphur dioxide kilning [50]. Thioesters are formed in hops largely by the action of heat, so low levels will be introduced into beer by dry hopping. Few sulphur volatiles survive 60 min of wort boiling but after late addition of hops to the copper most of the sulphur compounds discussed above are present in the wort including the thioesters. During fermentation dimethyl trisulphide and some of the thioesters disappear but some sulphur volatiles survive into the finished beer S-methyl 2-methylbutanethiolate is the principal thioester to survive. This last ester and 5-methyl hexanethiolate, the thioester with the lowest taste threshold, are the major thioesters introduced into beer by dry hopping [50]. 

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