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de - Beste verfügbare Techniken (BVT) - Umweltbundesamt

de - Beste verfügbare Techniken (BVT) - Umweltbundesamt de - Beste verfügbare Techniken (BVT) - Umweltbundesamt

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von bvt.umweltbundesamt.de Mehr von diesem Publisher
05.01.2013 Aufrufe

Chapter 2 Aromate, H 2SO 4 or oleum, SOCl 2 Salt, water, NaOH, chalk or lime, Na 2 CO 3 Water Water, filter auxiliaries Salt Sulphonation Precipitation Filtration Product washing Dissolving and filtration Recrystallisation Filtration Product SO 2 , SO 3 , VOC, HCl Gypsum/Na 2 SO 4 , CaCO 3 Mother liquor Wash-water Filter auxiliaries Second filtrate Figure 2.26: Typical sequence of operations for a sulphonation Possible input materials (on the left) and the associated waste streams (grey background) In the reactive extraction process, the unconverted sulphuric acid is recovered by converting the arylsulphonic acid into its ammonium salt with a long-chain aliphatic amine. This salt is separated from the sulphuric acid as a liquid phase and then converted with sodium hydroxide solution into sodium sulphonate solution and the amine; the latter can be separated as a liquid phase and can be re-used. Sulphonates practically free from inorganic salts are obtained in this way. Other isolation methods are based on the neutralisation of the excess sulphuric acid by adding calcium carbonate or sodium hydroxide. This leads to a large amount of gypsum (“liming” or “chalking”) or sodium sulphate, which is removed in the hot state. In liming, the dissolved calcium arylsulphonate is then treated with soda and the precipitated calcium carbonate is removed by filtration. The filtrate contains the sodium arylsulphonate. 60 Dezember 2005 OFC_BREF

2.5.13 Sulphonation with SO3 [15, Köppke, 2000] For environmental issues and the treatment of waste streams, see Section 4.3.2.9. Chapter 2 Sulphonation with SO3 is applied in the manufacture of a smaller number of aromatic sulphonic acids produced in higher volumes. Chemical reaction Sulphonation with SO3 is illustrated in Figure 2.27. The reaction does not lead to the formation of reaction water and shows higher selectivity if carried out at lower temperatures. Figure 2.27: Sulphonation with SO3 Side reactions: • formation of sulphones • formation of isomers • formation of oxidation by-products. R H SO 3H + SO 3 If carried out as a liquid phase reaction, halogenated compounds serve as solvents (e.g. methylene chloride or dichloroethane). Operations Figure 2.28 and Figure 2.29 show typical sequences of operations, possible input and related waste streams from the reaction in liquid phase and the gas-liquid reaction. Liquid phase reaction Both, the organic feed and SO3 are dissolved in organic solvents (e.g. methylene chloride or dichloroethane) and continuously added to the reactor. On completion, the reaction mixture is transferred into water and cooled. The organic phase is segregated and the product is precipitated from the aqueous phase by cooling and addition of sulphuric acid with subsequent filtration. OFC_BREF Dezember 2005 61 R Gas-liquid reaction Depending on the local conditions, SO3 gas is derived directly from a sulphuric acid facility or generated by combustion of sulphur. The reaction is usually carried out in falling film reactors. In many cases, it is not necessary to perform further work-up steps.

Chapter 2<br />

Aromate, H 2SO 4<br />

or oleum, SOCl 2<br />

Salt, water,<br />

NaOH, chalk or lime,<br />

Na 2 CO 3<br />

Water<br />

Water, filter auxiliaries<br />

Salt<br />

Sulphonation<br />

Precipitation<br />

Filtration<br />

Product washing<br />

Dissolving and filtration<br />

Recrystallisation<br />

Filtration<br />

Product<br />

SO 2 , SO 3 , VOC, HCl<br />

Gypsum/Na 2 SO 4 ,<br />

CaCO 3<br />

Mother liquor<br />

Wash-water<br />

Filter auxiliaries<br />

Second filtrate<br />

Figure 2.26: Typical sequence of operations for a sulphonation<br />

Possible input materials (on the left) and the associated waste streams (grey background)<br />

In the reactive extraction process, the unconverted sulphuric acid is recovered by converting the<br />

arylsulphonic acid into its ammonium salt with a long-chain aliphatic amine. This salt is<br />

separated from the sulphuric acid as a liquid phase and then converted with sodium hydroxi<strong>de</strong><br />

solution into sodium sulphonate solution and the amine; the latter can be separated as a liquid<br />

phase and can be re-used. Sulphonates practically free from inorganic salts are obtained in this<br />

way.<br />

Other isolation methods are based on the neutralisation of the excess sulphuric acid by adding<br />

calcium carbonate or sodium hydroxi<strong>de</strong>. This leads to a large amount of gypsum (“liming” or<br />

“chalking”) or sodium sulphate, which is removed in the hot state. In liming, the dissolved<br />

calcium arylsulphonate is then treated with soda and the precipitated calcium carbonate is<br />

removed by filtration. The filtrate contains the sodium arylsulphonate.<br />

60 Dezember 2005 OFC_BREF

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