The present invention relates to a process for preparing epichlorohydrin from dichlorohydrin comprising a step wherein the formed epichlorohydrin is recovered from the initial reaction mixture.

Processes for the preparation of epichlorohydrin from dichlorohydrin and a base are for example known from Organic Synthesis, Coll. Vol. 2, p. 256, Vol. 16, p. 30; Organic Synthesis, Coll. Col. 1, p. 233, Vol. 3, p. 47. These publications disclose process embodiments for the preparation of epichlorohydrin from dichlorohydrin by reaction with an inorganic base such as NaOH or Ca(OH) ₂ , after which the formed epichlorohydrin is recovered from the initial reaction mixture by distillation.

GB 2173496 describes a process for the production of epichlorohydrin by the epoxidation of a mixture composed of 70% 1 ,2-dichloropropanol and 30% 1 ,3-dichloropropanol in an aqueous solution. Said process is performed in a plate column and the epoxidation reaction is conducted simultaneously by rectifying distillation of the formed epichlorohydrin, using steam.

US 2008/0015369, US 2008/0015370, and US 2008/0045728 disclose processes for the preparation of epichlorohydrin using dichlorohydrin and caustic. The reaction is performed in a reactive distillation apparatus.

EP 1 059 278 A2 discloses the production of epichlorohydrin by supplying dichloropropanol and an aqueous alkali solution or suspension from the top of a plate distillation column, blowing steam from the bottom, and stripping epichlorohydrin produced by the reaction, while causing azeotropic distillation with water (boiling point 88°C), or by allowing the reaction of dichloropropanol and alkali to proceed in the presence of an inert solvent which was substantially insoluble in water while extracting epichlorohydrin in the solvent.

A disadvantage of recovering epichlorohydrin from the reaction mixture by distillation is that several undesired byproducts are formed, making for a poorer yield of epichlorohydrin and causing additional purification costs. In addition, epichlorohydrin and water form an azeotrope and consequently epichlorohydrin evaporation also requires evaporation of water, making distillation an energy-consuming operation. The use of an extractant to remove epichlorohydrin from the reaction mixture is undesired as either additional purification steps will be required or an epichlorohydrin product will be obtained which is contaminated with extractant. Furthermore, additional waste is generated. WO 2008/101866 and WO 2008/15245 disclose a process wherein epichlorohydrin is recovered from a reaction mixture obtained by reacting a mixture of dichloropropanol containing 1 ,3-dichloro-2-propanol and 2,3- dichloro-1 -propanol with at least one basic compound in order to form epichlorohydrin and a salt, by subjecting said reaction mixture to a settling operation. In this settling operation a first fraction containing most of the epichlorohydrin is obtained as well as a second aqueous fraction containing most of the salt. However, small density differences between the phases to be separated and the emulsifying behaviour of the phases will lead to poor separation efficiency via a settling operation (see data on densities of liquids present during epichlorohydrin production obtained from CRC Handbook of Chemistry and Physics, 79 ^th Edition 1998, David R. Lide, Editor-in-Chief). Thus long residence times are required, leading to additional by-product formation and thus requiring substantial capital investments. This problem is even more apparent when producing epichlorohydrin on pilot plant scale or larger, as it was observed that on such large scale more by-products (int. al. glycidol) are formed compared to lab scale reactions. In order to keep the amount of by-products as low as possible, it is important to mix the reactants as best as possible by stirring vigorously. However, more vigorous stirring will result in poorer separation and increases the risks of formation of an emulsion, which cannot by separated by the method according to WO 2008/101866 and WO 2008/15245. Furthermore, the operation at high dichlorohydrin conversion in the conventional process aggravates the emulsifying behaviour of the reaction mixture as well as further reducing the density difference between the phases. This can be remedied by the addition of solvent, but this will create new separation problems and environmental issues. Finally, the fraction containing most of the epichlorohydrin is contaminated with the salt which is formed upon reaction of dichloropropanol with the basic compound.

Therefore, it would be desirable to have an improved process for recovering epichlorohydrin from a reaction mixture obtained by reacting a mixture of dichloropropanol containing 1 ,3-dichloro-2-propanol and 2,3- dichloro-1 -propanol with at least one basic compound, which process does not have the above-mentioned disadvantages. It is an objective of the present invention to provide such a process.

It has surprisingly been found that this objective is met if the reaction mixture, obtained by reacting a mixture of dichlorohydrins (also generally denoted as dichloropropanol) containing 1 ,3-dichloro-2-propanol and 2,3- dichloro-1 -propanol with a base, is subjected to a membrane separation process. In more detail, the present invention relates to a process for preparing a product rich in epichlorohydrin comprising the steps of:

a) reacting a mixture of dichlorohydrins and a base at a temperature in the range from 0-65°C and during a period of time in the range from 1 second to 180 minutes to obtain an epichlorohydrin- containing reaction mixture comprising two liquid phases; and b) subjecting at least part of the reaction mixture as obtained in step a) to a membrane separation process wherein the mixture is separated into a first liquid stream which is rich in epichlorohydrin and a second liquid stream which is lean in epichlorohydrin.

Thus, a fast and efficient process for the preparation of a product rich in epichlorohydrin is obtained. The two-phase reaction mixture, obtained by reacting a mixture of dichlorohydrins (also denoted as DCH throughout the description) containing 1 ,3-dichloro-2-propanol and 2,3-dichloro-1 -propanol, is separated into 2 streams which both are practically homogeneous liquids and of which one is rich in epichlorohydrin and the other one is lean in epichlorohydrin. Surprisingly, this result is achieved even when the molecular weight of all components present in the two-phase reaction mixture is below the molecular weight cut-off of the membrane.

The first stream, i.e. the stream obtained in step (b) according to the process of the present invention which is rich in epichlorohydrin, can either be a permeate or a concentrate. Accordingly, the second stream, i.e. the stream obtained in step (b) according to the process of the present invention which is lean in epichlorohydrin, can also either be a permeate or a concentrate. As the skilled person will understand, this is dependent on the properties of the at least one membrane or membrane module used in the membrane separation step.

Throughout the description, when a stream as obtained from step (b) according to the process of the present invention, being either the permeate or the concentrate (also sometimes denoted as retentate), comprises at least 75% by weight of epichlorohydrin, preferably at least 85% by weight of epichlorohydrin, and most preferably at least 95% by weight of epichlorohydrin (based on the total weight of said stream), said stream is denoted as being "rich in epichlorohydrin". In other words, if a stream comprises at least 0.75 kg of epichlorohydrin per kg of said stream, and preferably at least 0.85 kg of epichlorohydrin per kg of said stream and most preferably at least 0.95 kg of epichlorohydrin per kg of said stream, it is denoted as being "rich in epichlorohydrin". Throughout the description, when a stream obtained from step (b) of the process of the present invention, being either the permeate or the concentrate, comprises less than 25% by weight of epichlorohydrin, preferably less than 15% by weight of epichlorohydrin, and most preferably less than 10% by weight of epichlorohydrin (based on the total weight of said stream) said stream is denoted as being "lean in epichlorohydrin". In other words, if a stream comprises less than 0.25 kg of epichlorohydrin per kg of said stream, and preferably less than 0.15 kg of epichlorohydrin per kg of said stream and most preferably less than 0.10 kg of epichlorohydrin per kg of said stream, it is denoted as being "lean in epichlorohydrin".

The wording "membrane separation process" is meant to denote a process step wherein a reaction mixture comprising two liquid phases as obtained in step a) of the process according to the present invention is separated into a permeate and a concentrate (also sometimes denoted as retentate) by means of at least one membrane or membrane module, whereby a liquid phase is present at both the concentrate and the permeate side of the membrane or membrane module and whereby the pressure at the feed side of the membrane or membrane module is higher than the pressure at the permeate side of the membrane or membrane module. This technology is often denoted as pressure driven membrane separation. The membrane or membrane module is preferably placed in a pressure vessel. As the skilled person will understand, it is often preferred to use two or more pressure vessels placed in parallel or in series in order to optimize the separation process (i.e. the process will have several stages). Said pressure vessels comprise one or more membranes or membrane modules.

The mixture of dichlorohydrins used in step a) of the present process can be obtained from several processes such as, for example, a conventional allyl chloride hypochlorination process, a conventional allyl alcohol chlorination process or a glycerol hydrochlorination process. Preferably, it is obtained from a glycerol hydrochlori nation process such as for example disclosed in DE 197308, WO 2005/021476, WO 2005/054167, WO 2006/020234, or Organic Synthesis, Coll. Vol. 1, p. 294 (1941 ); Vol. 2, p. 33 (1922).

In a preferred embodiment of the present invention, step a) and step b) are integrated, in order to allow reaction and separation to take place in one system. Step a) and step b) are preferably integrated by feeding a mixture of dichlorohydrins and a base to a so-called integrated reactor-membrane unit or membrane reactor. Mixing of the mixture of dichlorohydrins and the base and the conversion into epichlorohydrin take place inside the integrated reactor-membrane unit or membrane reactor, as does the membrane separation process providing a first stream which is rich in epichlorohydrin and a second stream which is lean in epichlorohydrin.

The reaction in step a) is generally carried out at a pH in the range of 7- 16. According to a preferred embodiment of this invention, the reaction (a) in the process is carried out at a pH of at most 15.5, more preferably at most 15. Preferably, the pH during said process step (a) is at least 8, and more preferably at least 1 1 . The pH during said process step (a) preferably is in the range of 8-16, more preferably in the range of 8-15.5, and most preferably in the range of 8-15.

The temperature in process step (a) of the present invention is at most 65°C, a preferred suitable temperature is at most 60°C, more preferably at most 55°C, even more preferably at most 45°C, and most preferably at most 35°C. On the other hand, the temperature in process step (a) is suitably at least 0°C, preferably at least 10°C, and more preferably at least 20°C. According to a preferred embodiment, the temperature due in process step (a) is in the range of 10-55°C, more preferably in the range of 20-45 °C, and most preferably in the range of 20-35°C. In process step (a) of the present invention the period of time for reacting the dichlorohydrin or the residence time may vary from 1 second to 180 minutes. Preferably, this residence time is at least 5 seconds and most preferably at least 15 seconds. On the other hand, the residence time in process step (a) preferably is at most 60 minutes, and more preferably at most 15 minutes. According to a preferred embodiment of the present invention, the residence time is in the range of 5 seconds to 60 minutes, and more preferably in the range of 15 seconds to 15 minutes. Preferably, in the process according to the present invention, the conversion of the mixture of dichlorohydrins into epichlorohydrin is at least 75%, based on the total amount of dichlorohydrin starting material. More preferably, at least 85%, more preferably at least 95%, most preferably at least 98% conversion of dichlorohydrin into epichlorohydrin (based on the total amount of dichlorohydrin starting material) is obtained in the overall process.

According to a preferred embodiment, reaction step (a) is carried out under mixing conditions and more preferably those caused by mechanical mixing, e.g. by using static mixers, because such conditions will lead to faster overall kinetics. In prior art processes wherein epichlorohydrin is recovered from the reaction mixture by a settling step such conditions cannot be applied, since they will aggravate the tendency of the reaction mixture to form an emulsion, which will subsequently lead to settling problems. In the process according to the present invention, it makes no difference whether or not an emulsion is formed in reaction step (a), since this does not have any detrimental effect on step (b).

The process of the present invention can be carried out in batch, semi- batch, and continuous mode. However, it is preferably carried out in a semi-batch or a continuous mode of operation in steps (a) - (b). More preferably, the process is carried out in a continuous mode of operation. In process step (a) of the present invention the applied base can be selected from a variety of inorganic or organic bases. Preferably, said base will be selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides. More preferably, sodium hydroxide or calcium hydroxide will be used in process step (a). Said base is preferably used in a molar ratio between base and dichlorohydrin in the mixture in process step (a) of at most 1 .2, preferably at most 1 .1 , and most preferably at most 1 .0.

Preferably, the base used in step a) is dissolved or suspended in an aqueous medium.

As already mentioned, the membrane separation process according to the present invention is a pressure driven membrane separation process. Preferably, it is a nanofiltration (NF) or an ultrafiltration membrane separation process. More particularly, in the membrane separation process according to the present invention preferably at least one nanofiltration membrane or membrane module is used or at least one ultrafiltration membrane or membrane module is used. Although less common, it is also possible to use at least one nanofiltration membrane or membrane module and at least one ultrafiltration membrane or membrane module. The nanofiltration or ultrafiltration membrane or membrane module used according to the invention is a conventional nanofiltration or ultrafiltration membrane or membrane module as specified in Figure 1 of Girard and Fukumoto, "Membrane Processing of Fruit Juices and Beverages: A Review", Critical Reviews in Food Science and Nutrition, 40 (2): 91 -157 (2000). In literature several definitions can be found for minimum and maximum molecular weight cut-offs for nanofiltration membranes and ultrafiltration membranes. A nanofiltration membrane or membrane module according to the present invention, however, has a molecular weight cut-off of at least 150 Dalton (Da), with the molecular weight cut-off being at most 1 ,000 Da. The nanofiltration system preferably utilizes semipermeable membranes of the nanofiltration type such as those sold as NF270 (FilmTec, The Dow Chemical Company), DESAL-5DK, DESAL-5DL, and DESAL-5HL (all GE/Osmonics), NTR7250 (Nitto Denko Industrial Membranes), AFC-30 (PCI Membrane Systems LTD), MPS-34 (Koch Membrane Systems), NP-030 (Nadir), SolSep-010306, SolSep-030306, and SolSep 030705 (all three SolSep BV) and Starmem 122 and Starmem 240 (both Grace/Davison). An ultrafiltration membrane or membrane module according to the present invention has a molecular weight cut-off of at least 1 ,000 Dalton (Da), with the molecular weight cut-off being at most 1 ,000,000 Da, preferably at most 250,000 Da, more preferably at most 25,000 Da, and most preferably at most 10,000 Da. The ultrafiltration system preferably utilizes semipermeable membranes of the ultrafiltration type such as those sold as DESAL G5/GE, DESAL G20/GK, DESAL G80/GN (all GE/Osmonics), NTR-7410 (Nitto Denko Industrial Membranes), HFK-131 (Koch Membrane Systems), NP010 (Nadir), SolSep 010104 (SolSep BV).

In order to determine whether or not a particular conventional nanofiltration or ultrafiltration membrane or membrane module is suitable for use in the process according to the present invention, the following simple test can be used.

A feed batch consisting of a 1 :1 (on a weight basis) mixture of epichlorohydrin and water is subjected to a separation step using a separation unit comprising a nanofiltration or an ultrafiltration membrane or membrane module at 20°C. The operating pressure during the test is set to create a membrane flux between 15 and 25 l.m ^"2 .h ^"1 for a nanofiltration membrane and between 30 and 50 l.m ^"2 .h ^"1 for an ultrafiltration membrane. If a pressure higher than 40 bar for nanofiltration or 10 bar for ultrafiltration is required to reach these membrane fluxes, the test will be conducted at 40 bar for the nanofiltration membrane and at 10 bar for the ultrafiltration membrane. In this test the separation unit is operated in total recycle mode, meaning that the produced permeate and concentrate are completely recycled to the feed supply vessel, apart from samples taken for analysis, which are withdrawn from the system. The weight fraction of the concentrate and permeate samples taken for analysis should be lower than 5% of the total feed supplied to the system. If the permeate comprises either 75% on weight basis or more of epichlorohydrin (i.e. at least 0.75 kg of epichlorohydrin per kg of permeate), or 75% on weight basis or more of water (i.e. at least 0.75 kg of water per kg of permeate), the membrane used in this test is suitable for use in the process according to the present invention.

This test can also be used to determine whether the suitable membrane produces a permeate rich in epichlorohydrin or a concentrate rich in epichlorohydrin.

Particularly good results are obtained in the process according to the invention with membranes which in the above-described test method provide a permeate comprising either 85% on weight basis or more of epichlorohydrin, or 85% on weight basis or more of water. Even better results are obtained in the process according to the invention with membranes which in the above-described test method provide a permeate comprising either 95% on weight basis or more of epichlorohydrin or 90% on weight basis or more of water.

In a particularly preferred embodiment of the present invention, a membrane is used which in the above-described test method provides a permeate comprising either 97% on weight basis or more of epichlorohydrin or 93% on weight basis or more of water. The specifications of the selected membrane as usually provided by the membrane supplier together with the information on process conditions given in this specification will provide the skilled person with all information required to be able to select the optimum conditions for performing the process according to the present invention with the selected membrane.

Several module types can be used for the membrane separation process according to the present invention (step (b)), e.g. spiral-wound modules, capillary systems, tubular systems, and hollow fibre systems. Preferably, spiral-wound modules or capillary modules are used. More preferably, spiral-wound modules are used. Step (b) according to the present invention is preferably carried out at a temperature of at most 65°C, more preferably at most 55°C, even more preferably at most 45°C, and most preferably at most 35°C. On the other hand, step (b) is preferably carried out at a temperature of at least 0°C, more preferably at least 10°C, and most preferably at least 20°C. In a preferred embodiment of step (b) the temperature is in the range of 0- 65°C, more preferably in the range of 10-55°C, even more preferably in the range of 20-45°C, and most preferably in the range of 20-35°C.

When step (b) is a nanofiltration membrane separation process, the separation is preferably carried out at a pressure of at most 80 bar, more preferably at most 60 bar, and most preferably at most 40 bar. However, when step (b) is an ultrafiltration membrane separation process, the separation is preferably carried out at a pressure of at most 20 bar, more preferably at most 15 bar, and most preferably at most 10 bar. As the skilled person will understand, step (b) is carried out with at least a positive pressure difference between concentrate and permeate.

It will be appreciated that an advantage of the process of the present invention and more in particular the process step (b) is that the obtained epichlorohydrin (the final product) comprises only a very small amount of alkali metal chloride or even none at all. Typically, the amount of alkali metal chloride or alkaline earth metal chloride in the final product is below 5% by weight, based on the total weight of the final product. More preferably, the amount of alkali metal chloride or alkaline earth metal chloride in the final product is below 2.5% by weight, even more preferably below 0.1 % by weight, even more preferably still below 0.05% by weight, and most preferably below 5 ppm. As mentioned above, the alkali metal chloride or alkaline earth metal chloride is produced upon reaction of dichloropropanol with a base, which preferably is a base selected from the group consisting of alkali metal hydroxides and alkaline earth metal hydroxides. Said alkali metal chloride or alkaline earth metal chloride will end up in the second stream, which is lean in epichlorohydrin.

In a preferred embodiment of the present invention, the reactor and the membrane separator are integrated, so that by-product formation is kept as low as possible. This means that the reactants (dichloropropanol and a base) are provided as feed to the membrane unit and the products (alkali metal chloride, epichlorohydrin (also denoted as ECH throughout the specification), by-products formed or non-reacted reactants) are removed from the membrane unit. An example of such an apparatus is presented in Fig.2. Persons skilled in the art will understand that many variations on the presented apparatus lay-out can be used to obtain the same advantage. A further advantage of integrating the reactor and the membrane separator is that operation at a high dichlorohydrin conversion is now feasible, even without the addition of a solvent (it is known that in conventional processes addition of a solvent is often necessary in order to effectuate an acceptable liquid-liquid separation). Optionally, the mixing of all the components in the membrane unit may be enhanced by the presence of in-line or static mixers in the unit. These static mixers may be used in different parts of the membrane unit such as, but not limited to, the suction or discharge side of the high-pressure pump or the recirculation pump(s). Persons skilled in the art will understand that several other locations of mixing-enhancing devices in the membrane unit may be used to enhance the mixing of the different liquid streams as well. If desired, epichlorohydrin from the first stream which is rich in epichlorohydrin as obtained from step b) may be recovered in a step c). In such a step c), water, dichlorohydrin, and/or impurities, or any mixture thereof can be removed from epichlorohydrin, and the water, dichlorohydrin, and/or impurities, or any mixture thereof may optionally be recirculated to step (a), and/or if applicable, another process step. Such a step c) can for instance be carried out by using known techniques such as distillation, centrifugation, adsorption, liquid-liquid separation, extraction, crystallization, filtration, another membrane separation step, and/or a series of one or more types of these techniques.

According to still another preferred embodiment of the present invention, one or more additional purification steps (d) may be applied to the stream lean in epichlorohydrin as obtained in process step (b) in order to recover various useful components, such as epichlorohydrin, dichlorohydrin, water, and/or impurities. Such a step d) can for instance be carried out by using known techniques such as distillation, centrifugation, adsorption, liquid-liquid separation, extraction, crystallization, filtration, another membrane separation step, and/or a series of one or more types of these techniques. These components can be obtained as separate product streams and/or as mixtures. In addition, these streams can be recirculated to appropriate steps of the present process, such as, for instance, step (a).

It will be appreciated that the starting mixture of dichlorohydrins for the reaction in process step (a) typically contains 1 ,2-dichlorohydrin and 1 ,3- dichlorohydrin. The skilled person will understand that it is also possible to use either 1 ,2-dichlorohydrin or 1 ,3-dichlorohydrin. Preferably, use is made of 1 ,3-dichlorohydrin. In Figure 1 two processes according to the present invention are schematically shown. Stream 1 represents a single stream or multiple streams containing the reactants required for the process. A base and dichlorohydrin should be present in this stream or in one of the separate streams fed to reactor a. This reactor can be a batch reactor, a semi- batch reactor, or a continuous reactor (see Figure 1 a). After the reaction, the crude reaction mixture 2 containing epichlorohydnn is separated in a membrane separation unit (b in Figure 1 a). The product which is rich in epichlorohydnn, stream 3 (a single stream or multiple streams), is subsequently purified in section c, leading to the epichlorohydrin- containing product (stream 4) and at least one stream 5. Depending on the composition of a stream 5, it can be re-used or it should be treated as waste. Unit operations that can be used to purify stream 3 may be state- of-the-art techniques such as distillation, centrifugation, adsorption, liquid- liquid separation, extraction, crystallization, filtration, another membrane separation, or a combination of several identical or different unit operations. The product which is lean in epichlorohydnn, stream 6 (a single stream or multiple streams), can be treated further in section (d) to remove, for example, any epichlorohydnn still present. Purification can be carried out with state-of-the-art techniques such as distillation, centrifugation, adsorption, liquid-liquid separation, extraction, crystallization, filtration, another membrane separation, or a combination of several identical or different unit operations. Stream 7 (a single stream or multiple streams) contains materials (e.g. epichlorohydnn and water) that can be used in other sections of the process. Stream 8 (a single stream or multiple streams) is a waste stream.

In a preferred embodiment of the present invention, the reactor (a) and the membrane separation unit (b) are combined in a single unit, a so- called integrated reactor-membrane unit or membrane reactor (see Figure 1 b). This operation mode has the advantage that less equipment and/or fewer unit operations are used. Figure 2 is a schematic depiction of a preferred flow chart for the above- disclosed process and represents the integrated reactor-membrane unit (a and b). A feed of a base and a mixture of dichlorohydrins is fed via inlet pipes 9 and 10, respectively, and via a first pump 1 1 and a second pump 12 to a pressure vessel 15 comprising one or more membrane modules. Several pressure vessels may be placed in parallel or in series, as is known to people skilled in the art. The concentrate is removed from the pressure vessel 15 via an outlet 14. Preferably, at least part of the concentrate is recycled via a pipe 20 and combined with the feed between pump 1 1 and pump 12. Static mixers 16, 17, 18, and 19 are optional. They may be present to increase mixing. However, often the use of the pumps is sufficient to effectuate mixing.

As the skilled person will understand, it is often preferred to use two or more pressure vessels 15 in series in order to optimize the separation process (i.e. the process will have several stages). Each stage may have its own recirculation pump, which means that the stream 14 will be fed to a second pump 12 and subsequently to a second pressure vessel 15.

In Figure 3 an apparatus suitable for the process of the present invention is depicted. In said apparatus, step (a) is performed inside the membrane separation unit. This apparatus comprises a pressure vessel (27) comprising at least one membrane or membrane module (28), said pressure vessel having at least two inlets (21 and 22) at the feed entrance side of the membrane module, one for feeding a mixture of dichlorohydrins and the other for feeding a base, and further comprising at least one outlet (23) to remove the concentrate from the pressure vessel, and at least one outlet (24) to remove the permeate from the pressure vessel. Preferably, the outlet to remove the concentrate from the pressure vessel (23) communicates with at least one of the inlets at the feed entrance side of the membrane module (21 and 22) via a first pump (26) for transporting part of the concentrate to said inlets. Said first pump (26) can be located upstream of the communication point of the outlet to remove the concentrate from the pressure vessel (23) and one of the at least two inlets at the feed entrance side of the membrane module (either inlet 21 or 22 as shown in Fig.3) or downstream of the communication point of the outlet to remove the concentrate from the pressure vessel (23) and the at least two inlets at the feed entrance side of the membrane module (either inlet 21 or 22). The membrane or membrane module (28) is a nanofiltration membrane or membrane module or an ultrafiltration membrane or membrane module. The process according to the present invention is further illustrated by the following non-limiting examples.

Example 1

Firstly, the reactor is filled with 349 g 1 ,3-dichloro-2-propanol (2.7 mol). A batch reactor is used that consists of a single-wall vessel of 1 liter (ID of 100 mm) equipped with four baffles, a Klopper bottom, an outlet valve at the bottom, and a glass stirrer. The position of the blades of the stirrer results in an upward fluid movement. Subsequently, 604 g 18% wt. sodium hydroxide (2.7 mol) is added, which is sufficient to convert all 1 ,3-dichloro-2-propanol. After the addition of sodium hydroxide, the stirrer is started (800 rpm) and the pH, temperature, and stirrer speed are monitored during the reaction that is continued for 60 minutes. The reaction is performed at atmospheric pressure and a temperature of 20°C.

Subsequently, the liquid mixture, consisting of a dispersed organic/brine phase (a liquid-liquid two-phase system) is pumped to a DSS LabStak M20 unit containing newly installed flat sheet SolSep 010306 (ex SolSep BV) and NF-90 (FilmTec™ ex The DOW Chemical Company) nanofiltration membranes. Both membranes have molecular weight cut-offs in excess of the molecular weights of all the components present in the feed. In total 0.072 m ² membrane surface area is installed. The trans-membrane pressure, the feed temperature, and the feed rate are 25 bar, 20°C, and 600 L/h, respectively. The membrane unit produces a single concentrate stream and permeates from the individual membranes. These are recycled to the reactor vessel to maintain full-recycle operation and unchanged feed conditions. The produced permeates are rich in ECH and each contain less than 0.4% wt. salt. As the skilled person will understand, a concentrate which is lean in ECH is eventually obtained if this process is continued with sufficient removal of permeate.

Example 2

Firstly, the reactor is filled with 349 g 1 ,3-dichloro-2-propanol (2.7 mol). A batch reactor is used that consists of a single-wall vessel of 1 liter (ID of 100 mm) equipped with four baffles, a Klopper bottom, an outlet valve at the bottom, and a glass stirrer. The position of the blades of the stirrer results in an upward fluid movement. Subsequently, 604 g 18% wt. sodium hydroxide (2.7 mol) is added, which is sufficient to convert all 1 ,3-dichloro-2-propanol. After the addition of sodium hydroxide, the stirrer is started (800 rpm) and the pH, temperature, and stirrer speed are monitored during the reaction that is continued for 60 minutes. The reaction is performed at atmospheric pressure and a temperature of 20°C.

Subsequently, the liquid mixture, consisting of a dispersed organic/brine phase (a liquid-liquid two-phase system) is pumped to a DSS LabStak M20 unit containing a newly installed flat sheet NTR 7250 (Nitto Denko obtained via Somicon) nanofiltration membrane. The membranes have a molecular weight cut-off in excess of the molecular weights of all the components present in the feed. In total 0.036 m ² membrane surface area is installed. The transmembrane pressure, the feed temperature, and the feed rate are 25 bar, 20°C, and 600 L/h, respectively. The membrane unit produces a single concentrate stream and permeates from the individual membranes. These are recycled to the supply vessel to maintain full-recycle operation and unchanged feed conditions. The produced permeate contained less than 3% wt. of ECH. The permeate, lean in ECH, contains 97% wt. brine of 22% wt. NaCI in water. As the skilled person will understand, a concentrate which is rich in ECH is eventually obtained if this process is continued with sufficient removal of permeate. Comparative Example A

Firstly, the reactor is filled with 349 g 1 ,3-dichloro-2-propanol (2.7 mol). A batch reactor is used that consists of a single-wall vessel of 1 liter (ID of 100 mm) equipped with four baffles, a Klopper bottom, an outlet valve at the bottom, and a glass stirrer. The position of the blades of the stirrer results in an upward fluid movement. Subsequently, 604 g 18% wt. sodium hydroxide (2.7 mol) is added, which is sufficient to convert all 1 ,3-dichloro-2-propanol. After the addition of sodium hydroxide, the stirrer is started (800 rpm) and the pH, temperature, and stirrer speed are monitored during the reaction that is continued for 60 minutes. The reaction is performed at atmospheric pressure and a temperature of 20°C.

Subsequently, the stirrer is stopped and liquid-liquid separation is performed in the same vessel at the same temperature and pressure. Liquid-liquid separation is stopped after 60 min, upon which 235 g of a product rich in epichlorohydrin are obtained and 716 g of a product lean in epichlorohydrin (2.1 g of material remain in the reactor after withdrawal of these phases). The obtained ECH-rich phase comprises 5.6% wt. of NaCI.

Example 3

A stream of 1 ,3-dichloro-2-propanol at a flow rate of 1 10 g/min (0.85 mmol/min DCH) and a stream of 18% wt. sodium hydroxide at a flow rate of 190 g/min (0.85 mmol/min NaOH), which is sufficient to convert all 1 ,3-dichloro-2- propanol, are pumped into a static mixer using two membrane pumps (DELTA 1608, Prominent Verder BV, the Netherlands). A kenics static mixer with helical elements is used (internal diameter 3.4 mm, length 191 mm, 27 elements). The static mixer is kept at a temperature of 20°C.

Subsequently, the liquid mixture produced, consisting of a dispersed organic/brine phase (a liquid-liquid two-phase system), is pumped via a stirred supply vessel to a DSS LabStak M20 unit containing newly installed flat sheet SolSep 010306 (ex SolSep BV) and NF-90 (FilmTec™ ex The DOW Chemical Company) nanofiltration membranes. Both membranes have molecular weight cut-offs in excess of the molecular weights of all the components present in the feed. In total 0.072 m ² membrane surface area is installed. The transmembrane pressure, the feed temperature, and the feed rate are 25 bar, 20°C, and 600 L/h, respectively. The membrane unit produces a single concentrate stream and permeates from the individual membranes. These are recycled to the reactor vessel to maintain full-recycle operation and unchanged feed conditions. The produced permeates are rich in ECH and each contain less than 0.4% wt. salt. As the skilled person will understand, a concentrate which is lean in ECH is eventually obtained if this process is continued with sufficient removal of permeate.

Example 4

A stream of 1 ,3-dichloro-2-propanol at a flow rate of 1 10 g/min (0.85 mmol/min DCH) and a stream of 18% wt. sodium hydroxide at a flow rate of 190 g/min (0.85 mmol/min NaOH), which is sufficient to convert all 1 ,3-dichloro-2- propanol, are pumped into a static mixer using two membrane pumps (DELTA 1608, Prominent Verder BV, the Netherlands). A kenics static mixer with helical elements is used (internal diameter 3.4 mm, length 191 mm, 27 elements). The static mixer is kept at a temperature of 20°C.

Subsequently, the liquid mixture produced, consisting of a dispersed organic/brine phase (a liquid-liquid two-phase system), is pumped via a stirred supply vessel to a DSS LabStak M20 unit containing a newly installed flat sheet NTR 7250 (Nitto Denko obtained via Somicon) nanofiltration membrane. The membranes have a molecular weight cut-off in excess of the molecular weights of all the components present in the feed. In total 0.036 m ² membrane surface area is installed. The trans-membrane pressure, the feed temperature, and the feed rate are 25 bar, 20°C, and 600 L/h, respectively. The membrane unit produces a single concentrate stream and permeates from the individual membranes. These are recycled to the supply vessel to maintain full-recycle operation and unchanged feed conditions. The produced permeate contained less than 3% wt. of ECH. The permeate, lean in ECH, contains 97% wt. brine of 22% wt. NaCI in water. As the skilled person will understand, a concentrate which is rich in ECH is eventually obtained if this process is continued with sufficient removal of permeate. Comparative Example B

A stream of 1 ,3-dichloro-2-propanol at a flow rate of 1 10 g/min (0.85 mmol/min DCH) and a stream of 18% wt. sodium hydroxide at a flow rate of 190 g/min (0.85 mmol/min NaOH), which is sufficient to convert all 1 ,3-dichloro-2- propanol, are pumped into a static mixer using two membrane pumps (DELTA 1608, Prominent Verder BV, the Netherlands). A kenics static mixer with helical elements is used (internal diameter 3.4 mm, length 191 mm, 27 elements). The static mixer is kept at a temperature of 20°C. After the static mixer, samples are taken. The samples are submitted to a liquid-liquid separation in a separation funnel. The separation is stopped after 60 min, upon which a product rich in epichlorohydrin is obtained and a product lean in epichlorohydrin is obtained. The obtained ECH-rich phase comprises 6.5 wt.% of NaCI.