de - Beste verfügbare Techniken (BVT) - Umweltbundesamt
de - Beste verfügbare Techniken (BVT) - Umweltbundesamt de - Beste verfügbare Techniken (BVT) - Umweltbundesamt
Chapter 2 Clarifying may be necessary on completion of the reaction (by filtration over SiO2, Al2O3 or charcoal) to remove unreacted amine and salty, resin-like or oily by-products, followed by precipitation of the product (usually by salting out or pH change), filtration, washing, dissolving and, e.g. spray drying to yield the standardised dyestuff. Alternatively, the reaction mixture is immediately passed through a pressure permeation (see also Section 4.2.26), followed by, e.g. belt, spin flash, spray or oven drying. Coupling component Alkali, H 2O Primary amine NaNO 2, HCl, H 2 O, Ice Alkali, buffer Ice Salt H 2 O H 2O Diazotisation Dissolving Filtration Filtration Precipitation Filtration Washing Dissolving Azo Coupling Drying Spray drying Product Permeation Mother liquor Permeate Wash-water Figure 2.13: Typical sequence of operations for diazotisation and azo coupling Possible input materials (on the left) and the associated waste streams (grey background) 44 Dezember 2005 OFC_BREF HCl
2.5.5 Esterification [6, Ullmann, 2001] Chapter 2 Organic esters are of considerable economic importance. Because of their highly lipophilic and hydrophobic nature and low polarity, esters are widely used as solvents, extractants, and diluents. Ethyl acetate is the most common technical solvent. Large quantities of esters, especially phthalates, adipates, and fatty acid esters, are used as plasticisers. Esters with a pleasant odour are used in fragrances, flavours, cosmetics, and soaps. Esters can be converted into various derivatives and are useful intermediates in the synthesis, e.g. of vitamins or pharmaceuticals. Chemical reaction A great variety of production methods for carboxylic acid esters are known, but the simplest and most common method of esterification is the reaction of an alcohol with a carboxylic acid with the elimination of water: R 1 C O OH Figure 2.14: Common esterification H + + R 2 OH R 1 C OFC_BREF Dezember 2005 45 O OR 2 + H 2O Esterification is the reverse of hydrolysis and leads to an equilibrium reaction, which is the reason that quantitative esterification is possible only by continuous removal of one of the products, i.e. ester or water. In the case of transesterification, an alcohol is released instead of water. Suitable catalysts are sulphuric acid, hydrogen chloride, arylsulphonic acids such as p-toluenesulphonic acid, and chlorosulphuric acid. Phosphoric acid, polyphosphoric acids, and mixtures of acids are also recommended. If the acids are adsorbed on a solid support, esterification can be carried out as a continuous process. Removal of water usually involves the addition of entrainers, which form azeotropes with relatively low boiling points and high water contents (usually toluene, xylene, cyclohexane, seldom also benzene or CCl4). Operations The reaction is generally carried out by refluxing the reaction mixture until all the water has been split off. The water or the ester is removed from the equilibrium by distillation. Water is usually removed by distillation of the azeotrope with the alcohol or an entrainer. After condensation, the azeotrope separates into an aqueous phase and an organic phase, and the entrainer or alcohol is recycled into the reaction mixture. In particular cases, a co-solvent such as benzene or toluene is added to the condensate to achieve separation of the organic phase. Many esters are produced continuously in pipes, distillation columns or plate columns. Ionexchange resins are especially suitable as catalysts in continuous processes. The reactants pass through or over the solid catalyst, and no separation or neutralisation of the catalyst is necessary.
- Seite 26 und 27: Abbildung 4.1: : Behandlungsschritt
- Seite 28 und 29: Verzeichnis der Tables bzw. Tabelle
- Seite 30 und 31: Tabelle 4.71: Weitere Beispiele fü
- Seite 33 und 34: 1 GENERAL INFORMATION 1.1 The secto
- Seite 35 und 36: Chapter 1 It is a feature of the se
- Seite 37 und 38: 1.3 Some products 1.3.1 Organic dye
- Seite 39 und 40: 1.3.1.3 Economics Chapter 1 The sca
- Seite 41 und 42: 1.3.2.3 Economics Chapter 1 The pha
- Seite 43 und 44: Pesticide group Pest group Insectic
- Seite 45 und 46: Real growth in % per year 8 3 -2 -7
- Seite 47 und 48: 1.3.7 Flame-retardants [6, Ullmann,
- Seite 49: 1.3.9 Explosives [46, Ministerio de
- Seite 52 und 53: Chapter 2 2.1.1 Intermediates [6, U
- Seite 54 und 55: Chapter 2 2.2 Multipurpose plants M
- Seite 56 und 57: Chapter 2 2.3 Equipment and unit op
- Seite 58 und 59: Chapter 2 2.3.2.2 Liquid-solid sepa
- Seite 60 und 61: Chapter 2 2.3.5 Energy supply [43,
- Seite 62 und 63: Chapter 2 2.3.7 Recovery/abatement
- Seite 64 und 65: Chapter 2 2.3.9 Groundwater protect
- Seite 66 und 67: Chapter 2 2.4 Site management and m
- Seite 68 und 69: Chapter 2 2.4.2.2 Solvents and vola
- Seite 70 und 71: Chapter 2 2.4.2.4 Biodegradability
- Seite 72 und 73: Chapter 2 2.5 Unit processes and co
- Seite 74 und 75: Chapter 2 2.5.3 Condensation [6, Ul
- Seite 78 und 79: Chapter 2 Co-solvent Acid, alcohol,
- Seite 80 und 81: Chapter 2 2.5.6 Halogenation [6, Ul
- Seite 82 und 83: Chapter 2 Operations Figure 2.18 sh
- Seite 84 und 85: Chapter 2 Organic feed, H 2 SO 4 ,
- Seite 86 und 87: Chapter 2 2.5.9 Oxidation with inor
- Seite 88 und 89: Chapter 2 2.5.11 Reduction of aroma
- Seite 90 und 91: Chapter 2 2.5.11.3 Alkali sulphide
- Seite 92 und 93: Chapter 2 Aromate, H 2SO 4 or oleum
- Seite 94 und 95: Chapter 2 Organic feed solvent SO 3
- Seite 96 und 97: Chapter 2 The product is isolated b
- Seite 98 und 99: Chapter 2 2.5.16 Processes involvin
- Seite 100 und 101: Chapter 2 2.6 Fermentation [2, Onke
- Seite 102 und 103: Chapter 2 Further steps can also be
- Seite 104 und 105: Chapter 2 2.7 Associated activities
- Seite 107 und 108: 3 CURRENT EMISSION AND CONSUMPTION
- Seite 109 und 110: Reference HCl HBr Cl2 Br2 SO2 NOx N
- Seite 111 und 112: 3.1.3 Mass flows Table 3.2 shows ma
- Seite 113 und 114: Reference 063E 082A,I(1) HCl 0.03 -
- Seite 115 und 116: Plant Before treatment COD BOD5 Aft
- Seite 117 und 118: 3.2.2 Reported emissions for inorga
- Seite 119 und 120: 3.2.3 Reported emission values for
- Seite 121 und 122: 4 TECHNIKEN, DIE BEI DER BESTIMMUNG
- Seite 123 und 124: Kapitel 4 Dies stellt für die Umge
- Seite 125 und 126: Medienübergreifende Effekte Wahrsc
2.5.5 Esterification<br />
[6, Ullmann, 2001]<br />
Chapter 2<br />
Organic esters are of consi<strong>de</strong>rable economic importance. Because of their highly lipophilic and<br />
hydrophobic nature and low polarity, esters are wi<strong>de</strong>ly used as solvents, extractants, and<br />
diluents. Ethyl acetate is the most common technical solvent. Large quantities of esters,<br />
especially phthalates, adipates, and fatty acid esters, are used as plasticisers. Esters with a<br />
pleasant odour are used in fragrances, flavours, cosmetics, and soaps. Esters can be converted<br />
into various <strong>de</strong>rivatives and are useful intermediates in the synthesis, e.g. of vitamins or<br />
pharmaceuticals.<br />
Chemical reaction<br />
A great variety of production methods for carboxylic acid esters are known, but the simplest and<br />
most common method of esterification is the reaction of an alcohol with a carboxylic acid with<br />
the elimination of water:<br />
R 1<br />
C<br />
O<br />
OH<br />
Figure 2.14: Common esterification<br />
H +<br />
+ R 2 OH R 1 C<br />
OFC_BREF Dezember 2005 45<br />
O<br />
OR 2<br />
+ H 2O<br />
Esterification is the reverse of hydrolysis and leads to an equilibrium reaction, which is the<br />
reason that quantitative esterification is possible only by continuous removal of one of the<br />
products, i.e. ester or water. In the case of transesterification, an alcohol is released instead of<br />
water.<br />
Suitable catalysts are sulphuric acid, hydrogen chlori<strong>de</strong>, arylsulphonic acids such as<br />
p-toluenesulphonic acid, and chlorosulphuric acid. Phosphoric acid, polyphosphoric acids, and<br />
mixtures of acids are also recommen<strong>de</strong>d. If the acids are adsorbed on a solid support,<br />
esterification can be carried out as a continuous process.<br />
Removal of water usually involves the addition of entrainers, which form azeotropes with<br />
relatively low boiling points and high water contents (usually toluene, xylene, cyclohexane,<br />
seldom also benzene or CCl4).<br />
Operations<br />
The reaction is generally carried out by refluxing the reaction mixture until all the water has<br />
been split off. The water or the ester is removed from the equilibrium by distillation. Water is<br />
usually removed by distillation of the azeotrope with the alcohol or an entrainer. After<br />
con<strong>de</strong>nsation, the azeotrope separates into an aqueous phase and an organic phase, and the<br />
entrainer or alcohol is recycled into the reaction mixture. In particular cases, a co-solvent such<br />
as benzene or toluene is ad<strong>de</strong>d to the con<strong>de</strong>nsate to achieve separation of the organic phase.<br />
Many esters are produced continuously in pipes, distillation columns or plate columns. Ionexchange<br />
resins are especially suitable as catalysts in continuous processes. The reactants pass<br />
through or over the solid catalyst, and no separation or neutralisation of the catalyst is<br />
necessary.