Improved process for production of alkali metal methoxides

Abstract

The present invention relates to a process for producing at least one alkali metal methoxide by reactive distillation in at least one reaction column. At the lower end of the reaction column(s), the respective alkali metal methoxide dissolved in methanol is withdrawn. The methanol / water mixture obtained at the top of the reaction column(s) is separated by distillation in a rectification column. The energy from the vapour obtained at the top of the rectification column is transferred to a liquid or gaseous heat transfer medium, and the gaseous heat transfer medium obtained as a result is compressed in at least two stages. The energy from the respectively compressed heat transfer medium is advantageously transferred to the bottom stream and sidestream from the rectification column. This enables particularly energy-efficient use of the energy from the vapour in the process of the invention. The energy from the compressed heat transfer medium may additionally be used for operation of the reaction column(s) or for operation of a reaction column in which a process for transalcoholization of alkali metal alkoxides is conducted.

Description

[0001] Improved process for the preparation of alkali metal methanolates

[0002] The present invention relates to a process for producing at least one alkali metal methoxide by reactive distillation in at least one reaction column. At the lower end of the reaction column(s), the respective alkali metal methoxide dissolved in methanol is withdrawn. The methanol / water mixture obtained at the top of the reaction column(s) is separated by distillation in a rectification column. The energy of the vapor obtained at the top of the rectification column is transferred to a liquid or gaseous heat transfer medium, and the resulting gaseous heat transfer medium is compressed in at least two stages. The energy of the compressed heat transfer medium is advantageously transferred to the bottom stream and side stream of the rectification column. This enables the particularly energy-efficient use of the vapor energy in the process according to the invention.

[0003] The energy of the compressed heat transfer medium can be used additionally for the operation of the reaction column(s) or for the operation of a reaction column in which a process for the transalcoholization of alkali metal alcoholates is carried out.

[0004] 1. Background of the invention

[0005] Alkali metal alkoxides are used as strong bases in the synthesis of numerous chemicals, for example, in the production of pharmaceutical or agricultural active ingredients. Furthermore, alkali metal alkoxides are used as catalysts in transesterification and amidation reactions.

[0006] Alkali metal alcoholates (MOR, where R is the alkyl radical of the respective alcohol, in particular R = Ci to Ce-alkyl, preferably methyl, ethyl, / so-propyl, n-propyl) are prepared by reactive distillation in a countercurrent distillation column from alkali metal hydroxides (MOH) and alcohols (ROH), wherein the product obtained according to the following reaction <1> The resulting reaction water is removed with the distillate.

[0007] MOH + ROH - MOR + H2O

[0008] Such a process principle is described, for example, in US Pat. No. 2,877,274 A, in which aqueous alkali metal hydroxide solution and gaseous methanol are run countercurrently in a reactive rectification column. This process is described again in essentially unchanged form in WO 01 / 42178 A1.

[0009] Similar processes, which additionally employ an entraining agent such as benzene, are described in GB 377,631 A and US 1,910,331 A. The entraining agent serves to separate water from the water-soluble alcohol. In both patents, the condensate undergoes phase separation to remove the water of reaction. Another similar process is the reaction of an alkali metal alkoxide with another alcohol in a reaction column ("transalcoholization") according to DE 2726 491 A1.

[0010] Accordingly, DE 96 89 03 C describes a process for the continuous production of alkali metal alkoxides in a reaction column, wherein the water-alcohol mixture withdrawn at the top is condensed and then subjected to phase separation. The aqueous phase is discarded, and the alcoholic phase is returned to the top of the column together with the fresh alcohol. EP 0 299 577 A2 describes a similar process, wherein the water is separated from the condensate using a membrane. The most industrially important alkali metal alkoxides are those of sodium and potassium, in particular the methylates and ethylates. Their synthesis has been described many times in the prior art, for example in EP 1 997 794 A1.

[0011] In the prior art syntheses of alkali metal alcoholates by reactive rectification, vapors are typically obtained that comprise the alcohol used and water. For economic reasons, it is sensible to reuse the alcohol contained in the vapors as a reactant in the reactive distillation. Therefore, the vapors are usually fed to a rectification column, and the alcohol contained therein is separated (described, for example, in GB 737453 A and US 4,566,947 A). The alcohol thus recovered is then fed, for example, as a reactant to the reactive distillation.

[0012] WO 2021 / 148174 A1 and WO 2021 / 148175 A1 describe the parallel production of various alkali metal alkoxides in separate reaction columns, whereby the vapors obtained from the respective reaction column are separated into the respective alcohol and water in a rectification column.

[0013] Alternatively or additionally, a portion of the alcohol vapor can be used to heat the rectification column (described in WO 2010 / 097318 A1). However, this requires the vapor to be compressed to reach the temperature level required to heat the rectification column. Multi-stage vapor compression is particularly thermodynamically advantageous. The vapor is cooled between compression stages. Furthermore, intercooling helps prevent the maximum permissible compressor temperature from being exceeded. The disadvantage of this cooling, as performed in conventional processes, is that the energy extracted is dissipated unused.

[0014] There is therefore a need for improved processes for processing an alcohol / water mixture in the context of a process for producing alkali metal alcoholates, where the alcohol is, in particular, methanol. This process should be characterized by a particularly efficient use of the energy contained in the vapor to operate the rectification column. 2. Brief Summary of the Invention

[0015] The present invention accordingly relates to a process for preparing at least one alkali metal methoxide of the formula MAOCH3, wherein MA is selected from sodium, potassium, lithium, in particular is selected from sodium, potassium, and is preferably sodium.

[0016] Optionally, simultaneously and spatially separated from the conversion to the alkali metal methoxide of the formula MAOCH3, in a second reaction column RR Banother alkali metal methoxide of the formula MBOCH3 is prepared, where MB is selected from sodium, potassium, lithium, in particular from sodium, potassium, and preferably potassium.

[0017] At the top of the reaction column RR A or the reaction columns RR A and RR B a vapor stream S AB or two vapor streams S AB and S BB , each comprising water and methanol. The stream S AB or the currents S AB and S BB are fed individually (i.e. not mixed together) or mixed together into a rectification column RD A and separated into water and methanol by distillation. Methanol is removed at the top of RD A as vapor stream S OA The energy of S OAis advantageously integrated into the process by means of a heat transfer medium W*i, which acts as a working medium. Energy is extracted from at least a portion of S OA transferred to the liquid or gaseous heat carrier W*i, whereby, if W*i is liquid, it at least partially evaporates. A gaseous heat carrier W*2 is thus obtained, both when W*i is gaseous and when W*i is liquid. The gaseous heat carrier W*2 is then at least partially compressed, resulting in a gaseous heat carrier W*3 that is more compressed than W*2. W*3 is divided into at least two parts W* 3i and W* 32 divided, and energy of W* 3i to a side stream SZÄ of the rectification column RD A transferred. W* 32 is further compressed, resulting in a higher density compared to W* 3i compressed gaseous heat carrier W*4 is obtained. Finally, energy from W*4 is transferred to a sump of RD A drawn current SUAi transferred and S UAi then in RD A returned.

[0018] In a further preferred aspect, the present invention relates to a process for the transalcoholization of alkali metal alkoxides. In this process, the alcohol residue of an alkali metal alkoxide M C OR' is replaced by another alcohol R"OH, where R' and R" are two different C1 to C2 hydrocarbon radicals, in particular R' = methyl and R" = C2 to C2 hydrocarbon radical, preferably R' = methyl and R" = ethyl, n-propyl, / so-propyl, more preferably R' = methyl and R" = ethyl.

[0019] M C OR' with R”OH in a reaction column to M C OR” and energy of W*3, especially W* 3i or W* 32 , or W*4 used in the process for alcohol conversion. 3. Figures

[0020] 3.1 Figure 1

[0021] Figure 1 shows a comparative process for the production of alkali metal methoxide in which the distillative separation of the methanol-water mixture is not carried out according to the invention.

[0022] Aqueous NaOH SAE2 <102> in a reaction column RR A <100> with methanol SAEI <103> converted to methanolic sodium methoxide solution. At the top of the reaction column RRA <100> an aqueous NaOH solution is used as reactant stream SAE2 <102> Alternatively, a methanolic NaOH solution can be used as reactant stream SAE2 <102> To produce the corresponding potassium methoxide, aqueous or methanolic KOH solution is used as reactant stream SAE2 <102> added. Above the bottom of the reaction column RRA <100> Methanol is used as a reactant stream SAEI <103> added in vapor form.

[0023] At the bottom of the reaction column RR A <100> a solution of the corresponding methanolate in methanol S Ap- <104> removed. With the sump evaporator V SA <105> and the optional evaporator V S A' <106> at the bottom of the column RR A <100> the concentration of the sodium methoxide solution S A p- <104> set to the desired value.

[0024] At the top of the reaction column RR A <100> becomes a vapor stream SAB <107> taken. In the capacitor K RRA <108> becomes part of the vapor stream SAB <107> condensed and liquid as reflux to the top of the reaction column RR A <100> abandoned. Capacitor K RRA <108> and the return setting are optional.

[0025] The preserved Brüden SAB <107> is transferred in whole or in part to a rectification column, the water / methanol column RD A <300> , fed into the rectification column RD A<300> contains fixtures <310> . In it, the water / methanol mixture is separated by distillation, and at its head methanol is released as vapors S OA <302> recovered by distillation.

[0026] At the rectification column RD A <300> A return flow is set. Part of the vapor SOA <302> is in a capacitor K RD <407> condensed. The condensation of the by K RD <407> conducted current can be stored in another capacitor behind K RD <407> with another cooling medium (water, air). The condensed part of the vapor SOA <302> is then returned to the rectification column RD A <300> The remaining part, ie not the capacitor K RD <407> supplied part of SOA <302> is carried out by means of compressor VD A B2 <303> compressed and to the reaction column RR A <100> recycled, where it is used as reactant stream SAEI <103> is used.

[0027] In capacitor KRD <407> Energy is provided by a part of SOA <302> to a liquid heat transfer medium W*i <701 >, which is preferably n-butane. W*i <701 > is thereby evaporated, and a gaseous heat transfer medium W*2 <702> received. W*2 <702> is fed to the compressor VDi <401>, where W*2 <702> if necessary, is additionally heated (not shown in Figure 1) before being fed to the compressor VDi <401>. In VDi <401>, W*2 <702> continue to the gaseous heat carrier flow W*3 <703> compressed, from which in the optional intercooler WT X <402> Energy can be dissipated.

[0028] W* 3 <703> is further compressed by means of compressor VD X <405> compressed and the resulting gaseous heat carrier flow W*4 <704> the evaporator V S RD <406> at the bottom of the rectification column RD A<300> for heating. The energy output is W*4 <704> again to W*i <701 >, in particular condensed W*4 <704> at least partially, whereby W*i <701 > is again obtained, which then goes through a new cycle as described above.

[0029] Fresh methanol <408> can be added to the process via the reflux into the rectification column RDA <300> be supplied.

[0030] At the bottom of the rectification column RD A <300> a water stream S UA <304> which is at least partially (current S UAi <320> ) back into the rectification column RD A <300> is returned, passing through the evaporator V S RD <406> and / or V S RD' <410> is conducted.

[0031] 3.2 Figure 2

[0032] Figure 2 shows another comparative process for the production of alkali metal methoxide in which the distillative separation of the methanol-water mixture is not carried out according to the invention.

[0033] This embodiment corresponds to the one described in Figure 1 with the following additional or different features: In addition to the evaporators V S RD' <406> and V S RD' <410> At the bottom, the rectification column RD A <300> an intermediate evaporator V Z RD <409> A side stream SZA <305> the rectification column RD A <300> taken and over

[0034] VZRD <409> then the rectification column RD A <300> fed back in. Part of the vapor stream S OA <302> is carried out by means of compressor VD A B2 <303> compressed and as reactant stream S A EGG <103> to the reaction column RR A <100> recycled.

[0035] The other part of the Brüden S OA <302> is in a capacitor K RD <407> condensed and then returned to the rectification column RD A <300> The condensation of the KRD <407> conducted current can be stored in another capacitor behind K RD <407> be completed with another cooling medium (water, air).

[0036] In capacitor K RD <407> energy is taken from a part of S OA <302> to a liquid heat transfer medium W*i <701 >, which is preferably n-butane. W*i <701 > is thereby evaporated, and a gaseous heat transfer medium W*2 <702> received. W*2 <702> is fed to the compressor VDi <401>, where it is further converted to the gaseous heat transfer stream W* 3 <703> is compressed, from which in the optional intercooler WT X <402> Energy can be dissipated.

[0037] The gaseous heat carrier flow W*3 <703> is fed to the intermediate evaporator V ZRD <409> for heating. Heating in the evaporator V S RD <406> or in the evaporator V S RD' <410> by W*3 <703> does not occur. Due to the energy release, W*3 <703> again to W*i <701 >, in particular condensed W*3 <703> at least partially, whereby W*i <701 > is again obtained, which then goes through a new cycle as described above.

[0038] 3.3 Figure 3

[0039] Figure 3 shows an embodiment of the process according to the invention. The rectification column RD used therein A <300> has an intermediate evaporator V ZRD <409> and a sump evaporator VSRD <406> and optionally the sump evaporator V S RD' <410> on.

[0040] This embodiment of the invention has the following differences from the embodiments described in Figures 1 and 2:

[0041] 1. After compression of the gaseous heat carrier W*2 <702> In the compressor VDi <401> the gaseous heat carrier flow W*3 <703> into two parts W* 3i <7031 > and W* 32 <7032> divided.

[0042] 2. W*3i <7031 > is added to the intermediate evaporator V ZRD <409> for heating the current S ZA <305> supplied.

[0043] 3. W* 32 <7032> is further in the compressor VD X <405> to the current W*4 <704> In an optional embodiment, W* 32 <7032> in the optional intercooler WT X <402> Energy dissipated before W* 32 <7032> is compacted. W*4 <704> is added to the sump evaporator VSRD <406> for heating the current S UAi <320> supplied.

[0044] 4. After W* 3i <7031 > and W*4 <704> the respective evaporator V ZRD<409> or VSRD <406> have left, and in particular by releasing energy to the respective stream condense, they are united and can undergo a new cycle as W*i <701 >.

[0045] Due to the differences in the inventive procedure and the distribution of the compressed gaseous heat carrier flow W*3 <703> into two parts W* 3i <7031 > and W* 32 <7032> , of which only W* 32 <7032> is additionally compressed, the energy of the once compressed stream W* 3i <7031 > or twice compressed current W*4 <704> Compared to the embodiment shown in Figures 1 and 2, it is more efficient for heating the rectification column RD A <300> via the intermediate evaporator V ZRD <409> or the sump evaporator VSRD <406> be recycled. 3.4 Figure 4

[0046] Figure 4 shows an embodiment of the process according to the invention. This corresponds to the embodiment described in Figure 3 with the difference that in a second reaction column RR B <200> an aqueous KOH solution S B E2 <202> , with methanol S BEi <203> is converted to potassium methoxide.

[0047] At the top of the reaction column RR B <200> an aqueous KOH solution is used as reactant stream S BE 2 <202> Alternatively, a methanolic KOH solution can be used as reactant stream S B E2 <202> Above the bottom of the reaction column RR B <200> Methanol is used as reactant stream S BEi <203> added in vapor form.

[0048] At the bottom of the reaction column RR B <200> a mixture of the corresponding methanolate in methanol S BP - <204> removed. With the sump evaporator V SB <205> and the optional evaporator V SB' <206> at the bottom of the column RR B <200> the concentration of the potassium methoxide solution S BP « <204> set to the desired value.

[0049] At the top of the reaction column RR B <200> becomes a vapor stream S BB <207> taken. In the capacitor K RRB <208> part of the vapor stream S BB <207> condensed and liquid as reflux to the top of the reaction column RR B <200> abandoned. Capacitor K RRB <208> and the return setting are optional.

[0050] The preserved Brüden S BB <207> is mixed with the not in the capacitor K RRA <108> condensed part of the vapor SAB <107> the rectification column RD A <300> Alternatively, the vapors S AB <107> and S BB <207> the rectification column RD A<300> can also be fed separately, i.e. at two different inlet points. These two inlet points are preferably located in the lower half of RD A <300> , preferably below the fixtures <310> .

[0051] Another difference to the embodiment according to Figure 3 is that the compressor VD AB2 <303> compressed part of the vapor S OA <302> partly to the reaction column RR A <100> and RR B <200> recycled, where it is used as reactant stream S AEi <103> or S BEi <203> is used.

[0052] 3.5 Figure 5

[0053] Figure 5 shows a further embodiment of the method according to the invention. This corresponds to the embodiment described in Figure 4 with the difference that a part of W*4 <704> also for heating the evaporator V SA ' <106> at the bottom of the column RR A <100> and the evaporator V SB' <206> at the bottom of the column RR B <200> is used. 3.6 Figure 6

[0054] Figure 6 shows a further embodiment of the process according to the invention. This corresponds to the embodiment described in Figure 5 with the difference that the reaction columns RR A <100> and RR B <200> one intermediate evaporator VZA <110> or VZB <210> A side stream SZAA <111> is fed to the reaction column RR A <100> taken and via VZA <110> then the reaction column RR A <100> fed back in. A side stream SZBA <211> the reaction column RR B <200> taken and over V ZB <210> then the reaction column RR B <200> fed back in.

[0055] In contrast to Figure 5, part of W*4 <704> only for heating the evaporator V SA ' <106> at the bottom of the column RR A<100> , but not for heating the evaporator V SB ' <206> at the bottom of the column RR B <200> used. In contrast, part of W* 3i <7031 > for heating the evaporator V ZB <210> used.

[0056] 3.7 Figure 7

[0057] Figure 7 shows a further embodiment of the process according to the invention. This corresponds to the embodiment described in Figure 5 with the difference that the reaction column RR A <100> an intermediate evaporator VZA <110> A side stream SZAA <111 > is fed to the reaction column RR A <100> taken and via VZA <110> then the reaction column RR A <100> In contrast to Figure 5, part of W*4 <704> only for heating the evaporator V SB ' <206> at the bottom of the RRB column <200> , but not for heating the evaporator V SA' <106> at the swamp of the RRA column <100> , used. The intermediate evaporator VZA <110> is transported by a pump <501> via a heat transfer medium W* <502> , especially water, which heats up in the intercooler WT X <402> from W'32 <7032> and in the intermediate evaporator VZA <110> gives up.

[0058] 3.8 Figure 8

[0059] Figure 8 shows a further embodiment of the process according to the invention. This corresponds to the embodiment described in Figure 5 with the difference that the reaction columns RR A <100> and RR B <200> one intermediate evaporator VZA <110> or VZB <210> A side stream SZAA <111> is fed to the reaction column RR A <100> taken and via VZA <110> then the reaction column RR A <100> fed back in. A side stream SZBA <211> the reaction column RR B<200> taken and via VZB <210> then the reaction column RR B <200> fed back in.

[0060] In addition, Figure 8 shows a further preferred embodiment of the process according to the invention. It shows a reactive rectification column RR C <600> for the transalcoholization of sodium methoxide to sodium ethoxide, which is at least partly produced with energy from the stream W*32 <7032> operated. The column RR C <600> has the sump evaporator V S c <605> and Vsc <606> on.

[0061] Sodium methoxide solution S C EGG <602> in a reaction column RR C <600> in countercurrent with ethanol S C E2 <603> TO sodium ethanolate and this as ethanolic solution S C p <604> taken.

[0062] At the bottom of the reaction column RR C <600> a bottom product stream S C p <604> comprising sodium ethanolate.

[0063] At the top of the reaction column RR C <600> becomes a vapor stream S C B <607> Preferably, the capacitor K RRC <608> at least part of the vapor stream S C B <607> condensed and at least a part of it is returned in liquid form to the top of the reaction column RRc <600> abandoned. The vapor stream S C B <607> is partly either gaseous in front of the condenser K RRC <608> deducted (shown by dashed line) and / or partly as current <609> liquid behind the capacitor K RRC <608> .

[0064] A side stream Szc <610> the reaction column RR C <600> preferably removed, whereby this is fed via an intermediate evaporator Vzc <611> Energy is transferred and Szc <610> then back in RR C <600> can be redirected.

[0065] As sodium methoxide solution S CEGG <602> Preferably, at least part of the in the reaction column RR A <100> and RR B <200> extracted swamp streams S AP - <104> or S BP « <204> used.

[0066] The sump evaporator Vsc <606> is transported by a pump <501> via a heat transfer medium W* <502> , especially water, which heats up in the intercooler WTx <402> by W32 <7032> and in the sump evaporator Vsc <606> gives up.

[0067] Alternatively, energy can be supplied by another power source selected from W*4 <704> , W*3i <7031 >, W*3 <703> before separation into W* 3i <7031 > and W32 <7032> , on the sump evaporator Vsc <606> or the other sump evaporator Vsc <605> be transmitted. From at least one of the streams W*3 <703> , W31 <7031 >, W'32 <7032> , W*4 <704> can also transfer energy to the ethanol stream S C EGG <603> , the sodium methoxide solution S CEGG <602> or the side stream Szc <610> be transferred.

[0068] 3.9 Figure 9

[0069] Figure 9 shows an embodiment of the process according to the invention. This corresponds to the embodiment described in Figure 8 with the difference that the heating of the bottom evaporator Vsc <606> directly with a part of W*4 <704> 3.10 Figure 10

[0070] Figure 10 illustrates the energy savings in the process according to the invention according to Example 3 compared to the non-inventive process according to Examples 1 and 2. The x-axis denotes the respective example, the y-axis the power to be generated in MW.

[0071] The hatched part of the bars indicates the total compressor power. The white part of the bars represents the required heating power from low-pressure steam.

[0072] 4. Detailed description of the invention

[0073] The present invention relates to a process for preparing at least one alkali metal methoxide of the formula MAOCHS, wherein MA is selected from sodium, potassium, lithium, preferably sodium, potassium, and MA is most preferably sodium.

[0074] The process according to the invention is carried out in at least one reactive rectification column, and the vapor streams obtained in the at least one reactive rectification column, which comprise methanol and water, are then at least partially separated into water and methanol in a reaction column. This distillative separation efficiently integrates the energy of the vapors obtained.

[0075] 4.1 Step (a1)

[0076] In step (a1) of the process according to the invention, a reactant stream SAEI comprising methanol is reacted with a reactant stream SAE2 comprising MAOH in countercurrent in a reactive rectification column RRA to form a crude product RP Acomprising MAOCHS, water, methanol, MAOH.

[0077] According to the invention, a "reactive rectification column" is defined as a rectification column in which at least some of the reaction takes place according to step (a1) or step (a2) of the process according to the invention. It can also be abbreviated to "reaction column."

[0078] In step (a1) at the lower end of RR A a bottom product stream S A p containing methanol and MAOCHS. At the upper end of RR A a vapor stream SAB comprising water and methanol is withdrawn.

[0079] MA is selected from sodium, potassium, and lithium. MA is particularly selected from sodium and potassium. MA is preferably sodium.

[0080] The reactant stream SAEI comprises methanol. In a preferred embodiment, the mass fraction of methanol in SAEI is >95 wt. %, more preferably >99 wt. %, with SAEI otherwise comprising, in particular, water. The methanol used as reactant stream SAEI in step (a1) can also be commercially available methanol with a methanol mass fraction of more than 99.8 wt. % and a water mass fraction of up to 0.2 wt. %.

[0081] The reactant stream SAEI is preferably added in vapor form.

[0082] The reactant stream SAE2 comprises MAOH. In a preferred embodiment, SAE2 comprises, in addition to MAOH, at least one further compound selected from water and methanol. Even more preferably, SAE2 also comprises water in addition to MAOH, in which case SAE2 is an aqueous solution of MAOH.

[0083] When the reactant stream SAE2 comprises MAOH and water, the mass fraction of MAOH, based on the total weight of the aqueous solution forming SAE2, is in particular in the range from 10 to 75 wt.%, preferably from 15 to 54 wt.%, more preferably from 30 to 53 wt.% and particularly preferably from 40 to 52 wt.%.

[0084] When the reactant stream SAE2 comprises MAOH and methanol, the mass fraction of MAOH in methanol, based on the total weight of the solution forming SAE2, is in particular in the range from 10 to 75 wt.%, preferably from 15 to 54 wt.%, more preferably from 30 to 53 wt.%, and particularly preferably from 40 to 52 wt.%.

[0085] In the particular case in which the reactant stream SAE2 comprises both water and methanol in addition to MAOH, it is particularly preferred that the mass fraction of MAOH in methanol and water, based on the total weight of the solution forming SAE2, is in particular in the range from 10 to 75 wt.%, preferably from 15 to 54 wt.%, more preferably from 30 to 53 wt.%, and particularly preferably from 40 to 52 wt.%.

[0086] Step (a1) is carried out in a reactive rectification column (or “reaction column”) RR A carried out.

[0087] Step (a2), which is explained below, is carried out in a reactive rectification column (or “reaction column”) RR B carried out.

[0088] Preferably, the reaction column RR contains A or RR B Internals. Suitable internals include trays, structured packings, or unstructured packings. If the reaction column RR A or RR BIf the reaction column contains trays, bubble cap trays, valve trays, tunnel trays, Thormann trays, cross-slotted bubble cap trays or sieve trays are suitable. If the reaction column RR A or RR B If the reactor contains multiple trays, trays are preferably selected in which a maximum of 5% by weight, preferably less than 1% by weight, of the liquid permeates through the respective trays. The design measures required to minimize permeation of the liquid are familiar to those skilled in the art. For valve trays, for example, particularly tightly closing valve designs are selected. By reducing the number of valves, the vapor velocity in the tray openings can also be increased to twice the value that is usually set. When using sieve trays, it is particularly advantageous to reduce the diameter of the tray openings and maintain or even increase the number of openings.

[0089] When using structured or unstructured packings, structured packings are preferred with regard to the even distribution of the liquid.

[0090] For columns with unstructured packings, particularly with random packings, and for columns with structured packings, the desired liquid distribution characteristics can be achieved by reducing the liquid sprinkling density in the edge region of the column cross-section adjacent to the column shell, which corresponds to approximately 2 to 5% of the total column cross-section, by up to 100%, preferably by 5 to 15%, compared to the remaining cross-sectional areas. This can be achieved, for example, by the targeted distribution of the drip points of the liquid distributors or their bores using simple means.

[0091] The process according to the invention can be carried out both continuously and batchwise. It is preferably carried out continuously.

[0092] The “conversion of a reactant stream SAEI comprising methanol with a reactant stream SAE2 comprising M A OH in countercurrent” is ensured according to the invention in particular by the feed point of at least a part of the reactant stream SAEI comprising methanol in step (a1) at the reaction column RR A below the feed point of the reactant stream SAE2 comprising MAOH.

[0093] The reaction column RR A preferably comprises at least 2, in particular 15 to 40 theoretical stages between the feed point of the reactant stream SAEI and the feed point of the reactant stream S A E2.

[0094] The reaction column RR A can be operated as a pure stripping column. Then, in the lower section of the reaction column RR AThe reactant stream SAEI comprising methanol is fed in vapor form.

[0095] Step (a1) also includes the case where a part of the reactant stream SAEI comprising methanol is below the feed point of the reactant stream SAE2 comprising MAOH, but nevertheless at the upper end or in the region of the upper end of the reaction column RR A This allows the dimensions in the lower section of the reaction column RR A If a part of the reactant stream SAEI comprising methanol is at the top or in the region of the top of the reaction column RR A in particular in vaporous form, only a partial amount of 10 to 70 wt.%, preferably 30 to 50 wt.% (in each case based on the total amount of methanol used in step (a1)) is added at the lower end of the reaction column RR Afed in and the remaining portion is added in a single stream or distributed over several substreams, preferably 1 to 10 theoretical stages, particularly preferably 1 to 3 theoretical stages below the feed point of the reactant stream SAE2 comprising MAOH in vapor form.

[0096] In the reaction column RR A the reactant stream S AEi comprising methanol with the reactant stream S AE 2 comprising MAOH according to the reaction described above <1> to MAOCHS and H2O, whereby, since this is an equilibrium reaction, these products are present in a mixture with the reactants methanol and MAOH. Accordingly, in step (a1) a crude product RP A in the reaction column RR A which, in addition to the products MAOCHS and water, also includes methanol and MAOH.

[0097] At the lower end of RR A The bottom product stream S is then obtained and removed AP comprising methanol and MAOCHS.

[0098] At the top of RR A , preferably at the column head of RR A , the stream of methanol still containing water, referred to above as “vapor stream S AB comprising water and methanol”.

[0099] This vapor stream S AB comprising water and methanol is in step (a3) ​​at least partially introduced into a rectification column RD A and there distilled at least partially into a vapor stream S OA comprising methanol, which is at the upper end of RD A is taken, and at least one current S UA comprising water, which is at the lower end of RD A In the embodiments of the present invention in which step (a2) is carried out, additionally at least a portion of the vapor stream S BB , mixed with S AB or separately from S AB , into the rectification column RD A led.

[0100] Part of the product obtained during the distillation in step (a3) ​​in stream S OA The methanol obtained can be added to the reaction column RR A as reactant stream S AEi be supplied.

[0101] In a preferred embodiment of the process according to the invention, a part of S OA in step (a1) as reactant stream S AEi and, if step (a2) is carried out, alternatively or additionally in step (a2) as reactant stream S BEi used.

[0102] In a more preferred embodiment of the process according to the invention, 5 to

[0103] 95 wt.%, preferably 10 to 90 wt.%, more preferably 20 to 80 wt.%, even more preferably 30 to

[0104] 70 wt.%, more preferably 50 to 60 wt.%, more preferably 56.7 wt.% of the vapor stream S OAas reactant stream SAEI or, if step (a2) is carried out, alternatively or additionally in step (a2) as reactant stream SBEI.

[0105] In this preferred embodiment, it is advantageous to use the part of the current S OA , which is used as reactant stream S AEi or to compress the reactant stream SBEI.

[0106] The amount of reactant stream S AEi The methanol contained in the bottom product stream S AP obtained alkali metal methanolate MAOCHS. Preferably, the amount of methanol in the reactant stream S AEi selected so that the desired concentration of the alkali metal methoxide solution is present in the bottom of the reaction column, which is available as bottom product stream S AP comprising methanol and MAOCHS.

[0107] In a preferred embodiment of the method according to the invention, and in particular in cases where S AE2 in addition to MAOH also includes water, the ratio of the total weight (mass; unit: kg) of in step (a1) as reactant stream S AEi methanol used to the total weight (mass; unit: kg) in step (a1) as reactant stream S AE2 used MAOH 4 : 1 to 50 : 1 , more preferably 8 : 1 to 48 : 1 , even more preferably 10 : 1 to 45 : 1 , even more preferably 20 : 1 to 40 : 1 , even more preferably 22 : 1 .

[0108] The reaction column RR A is operated with or without, preferably with return.

[0109] “With reflux” means that the reflux at the top of the respective column, in step (a1) of the reaction column RR A , in the optional step (a2) of the reaction column RR B , extracted vapor stream S AB or S BBcomprising water and methanol is not completely removed. In step (a3), the vapor stream S in question is AB or S BB therefore not completely into a rectification column RD A but at least partly, preferably partly, again as reflux of the respective column, in step (a1) of the reaction column RR A , in the optional step (a2) of the reaction column RR B , is supplied. In cases where such a reflux is established, the reflux ratio is preferably 0.01 to 1, more preferably 0.02 to 0.9, even more preferably 0.03 to 0.34, even more preferably 0.04 to 0.27, even more preferably 0.05 to 0.24, even more preferably 0.06 to 0.10, even more preferably 0.07 to 0.08.

[0110] A reflux can be established by attaching a condenser to the top of the respective column. In step (a1), this is done in particular at the reaction column RR A a capacitor KRRA In step (a2) the reaction column RR B a capacitor K RRB In the respective condenser, the respective vapor stream S AB or S BB at least partially condensed and the respective column, in step (a 1 ) of the reaction column RR A or in step (a2) of the reaction column RR B is fed back in. In the embodiment in which the reaction column RR A a return flow is established, the MAOH used in step (a1) as reactant stream SAE2 can also be at least partially mixed with the return flow and the resulting mixture can thus be fed to step (a1).

[0111] Step (a1) is carried out in particular at a temperature in the range from 45 °C to 150 °C, preferably 47 °C to 120 °C, more preferably 60 °C to 110 °C, and at a pressure of 0.5 bar abs. to 40 bar abs., preferably in the range from 0.7 bar abs. to 5 bar abs., more preferably in the range from 0.8 bar abs. to 4 bar abs., more preferably in the range from 0.9 bar abs. to 3.5 bar abs., even more preferably at 1.0 bar abs. to 3 bar abs., even more preferably 1.25 bar abs.

[0112] The reaction column RR A In a preferred embodiment, comprises at least one evaporator, which in particular consists of intermediate evaporators VZA and bottom evaporators V SA is selected. The reaction column RR A particularly preferably comprises at least one bottom evaporator V SA .

[0113] As an “intermediate evaporator” V zAccording to the invention, evaporators are referred to which are located above the bottom of the respective column, in particular above the bottom of the reaction column RR A or RR B (then as “VZA” or “V ZB “) or above the bottom of the rectification column RD A (then as “V Z RD”). In the case of RR A or RR B In particular, raw product RP A or RP B evaporated, which is fed to the column as side stream S ZAA or S ZBA is taken.

[0114] As a “sump evaporator” V s According to the invention, evaporators are referred to which the bottom of the respective column, in particular the bottom of the reaction column RR A or RR B or the RR used in the preferred embodiment and described in more detail below C (then as “V SA ' or 'V SA '“ or “V S B" or "V SB'" or "V S c" or "V S c'") or the bottom of the rectification column RD A (then as “V S RD" or "V S RD'”). In the case of RR A or RRB, in particular at least a part of the bottom product stream S AP or S B p evaporates. In the case of RR C In particular, bottom product stream S C p evaporates. In the case of RD A In particular, bottom product stream S UA or part of S UA , S UA i, evaporates.

[0115] An evaporator is usually located outside the respective reaction column or rectification column. Since energy, especially heat, is transferred from one stream to another in evaporators, they are heat transfer devices (WT). The mixture to be evaporated is withdrawn from the column via an outlet and fed to at least one evaporator. In the case of the reaction column (RR), A or RR B is used during the intermediate evaporation of the raw product RP A or RP B , this is withdrawn and fed to at least one intermediate evaporator VZA or VZB.

[0116] In the case of the rectification column RD A During the intermediate evaporation at least one side stream SZÄ from RD A removed (“withdrawn”) and fed to at least one intermediate evaporator VZRD.

[0117] In the case of the rectification column RD A During the bottom evaporation at least one stream S UA from RD Aremoved (“withdrawn”) and at least one part, preferably a part, to which at least one bottom evaporator V S RD supplied.

[0118] The evaporated mixture, possibly with a residual liquid portion, is returned to the respective column via at least one inlet. If the evaporator is an intermediate evaporator, in particular an intermediate evaporator of the FTE or V ZB or VZRD, the outlet through which the respective mixture is withdrawn and fed to the evaporator is a side outlet, and the inlet through which the evaporated mixture is fed back to the respective column is a side inlet. If the evaporator is a bottom evaporator, i.e., it heats the column bottom, in particular a bottom evaporator V SA or V SB or VSRD, at least part of the bottoms effluent stream, in particular S AP or S BP, fed to the bottom evaporator, evaporated, and returned to the respective column in the bottom area. Alternatively, it is also possible, for example, to form tubes on a suitable tray when using an intermediate evaporator or in the bottom of the respective column, which are fed by the heat transfer medium, e.g. the respective compressed heat transfer medium W* 3i or W*4(if V s or V z at the rectification column RD A located) or a heat transfer medium Wi. In this case, evaporation takes place at the bottom or bottom of the column. However, it is preferable to locate the evaporator outside the respective column.

[0119] Suitable evaporators that can be used as intermediate evaporators and bottom evaporators include natural circulation evaporators, forced circulation evaporators, forced circulation evaporators with expansion, boiler evaporators, falling-film evaporators, or thin-film evaporators. A tube bundle or plate apparatus is typically used as the heat exchanger for the evaporator in natural circulation evaporators and forced circulation evaporators. When using a tube bundle exchanger, the heat transfer medium, e.g., the compressed heat transfer medium W*, can be used. 3i or W*4in VZRD or V S RD at the rectification column RD A or the heat transfer medium Wi either flows through the pipes and the mixture to be evaporated flows around the pipes or the heat transfer medium, e.g. the compressed heat transfer medium W* 3i or W*4in VZRD or VSRD at the rectification column RD AThe heat transfer medium Wi flows around the tubes, and the mixture to be evaporated flows through them. In a falling-film evaporator, the mixture to be evaporated is usually added as a thin film on the inside of a tube, and the tube is heated from the outside. In contrast to a falling-film evaporator, a thin-film evaporator also features a rotor with wipers, which distributes the liquid to be evaporated into a thin film on the inside wall of the tube.

[0120] In addition to those mentioned, any other type of evaporator known to the person skilled in the art that is suitable for use in a rectification column can also be used.

[0121] If the evaporator, which is e.g. connected to the compressed heat carrier W* 3i or the heat transfer medium Wi is operated as heating steam, it is preferred if the intermediate evaporator in the stripping section of the rectification column RD Ain the area between the inlet point(s) of the vapor stream SAB or the vapor stream SBB and above the column bottom or, in the case of the reaction columns RR A or RR B below the inlet point of the reactant stream S AE 2 or S B E2. This allows a predominant portion of the heating energy to be introduced through the intermediate evaporator. For example, it is possible to introduce more than 80% of the energy via the intermediate evaporator. According to the invention, the intermediate evaporator is preferably arranged and / or designed such that it introduces more than 10%, in particular more than 20%, of the total energy required for distillation.

[0122] When using an intermediate evaporator, it is particularly advantageous if the intermediate evaporator is arranged such that the respective rectification column or reaction column has 1 to 50 theoretical plates below the intermediate evaporator and 1 to 200 theoretical plates above the intermediate evaporator. It is particularly preferred if the rectification column or reaction column has 2 to 10 theoretical plates below the intermediate evaporator and 20 to 80 theoretical plates above the intermediate evaporator.

[0123] The side draw stream through which the mixture from the rectification column or reaction column is fed to the intermediate evaporator V z and the side inlet, through which the evaporated mixture from the intermediate evaporator V zThe side draw and side inlet can be positioned between the same trays of the column and fed back into the respective rectification or reaction column. However, it is also possible for the side draw and side inlet to be at different heights.

[0124] In such an intermediate evaporator V ZA can be used in the reaction column RR A liquid raw product RP A comprising MAOCHS, water, methanol, MAOH into the gaseous state, thus improving the efficiency of the reaction according to step (a1) of the process according to the invention. In such an intermediate evaporator VZB, in the reaction column RR B liquid raw product RP B comprising MBOCH3, water, methanol, MBOH are converted into the gaseous state, and thus the efficiency of the reaction according to step (a2) of the process according to the invention is improved.

[0125] By arranging one or more intermediate evaporators VZÄ in the upper section of the reaction column RR A the dimensions in the lower part of the reaction column RR A In the embodiment with at least one, preferably several, intermediate evaporators VZÄ it is also possible to use partial streams of methanol in liquid form in the upper region of the reaction column RR A to supply.

[0126] In a further preferred embodiment, energy, preferably heat, is extracted from at least a portion of a heat carrier, wherein the heat carrier is selected from W*2, W*3, W*4, preferably from W*3, W*4, more preferably from W*3, W* 32 is selected, even more preferably W* 32 is, on the raw product RP A and, if step (a2) is carried out, alternatively or additionally to the crude product RP Btransferred. At least one part of W*3 is in particular from W*3i, W* 32 selected.

[0127] “Transfer of energy, preferably heat, from at least a part of a heat carrier, wherein the heat carrier is selected from W*2, W*3, W*4, to the crude product RPA and, if step (a2) is carried out, alternatively or additionally to the crude product RPB” therefore also includes the transfer of energy, preferably heat, from at least one heat carrier selected from W*3i, W* 32 , or from the heat carrier W*3 before its separation into W*3i, W* 32 , on the raw product RP A and, if step (a2) is carried out, alternatively or additionally to the crude product RP B . It also includes the transfer of energy from a part of W*3i, W* 32 on the raw product RP A and, if step (a2) is carried out, alternatively or additionally to the crude product RP B .

[0128] For this purpose, a part of the heat transfer medium in question is selected from W*2, W*3, W*4, at least partially via an intermediate evaporator VZÄ or V ZB and the energy from the respective heat carrier selected from W*2, W*3, W*4 to the side discharge from RR A or RR B withdrawn raw product stream, in particular in which the heat transfer medium in question is selected from W*2, W*3, W*4 for heating the evaporator VZÄ or V ZB is used. Optionally, in this embodiment, a heat carrier W* different from W*2, W*3, W*4 is "interposed". This means that first, energy, in particular heat, is transferred from at least one heat carrier selected from W*2, W*3, W*4 to W*, and then the energy from W* is transferred to the side discharge from RR A or RR B withdrawn raw product stream, in particular in the W* for heating the evaporator VZÄ or V ZBis used. Any heat transfer medium known to the person skilled in the art can be used as heat transfer medium W*; preferably, W* is selected from the group consisting of air, water; alcohol-water solutions; salt-water solutions, which also include ionic liquids, such as LiBr solutions, dialkylimidazolium salts, such as in particular dialkylimidazolium dialkylphosphates;

[0129] Mineral oils, such as diesel oils; thermal oils, such as silicone oils; biological oils, such as limonene; aromatic hydrocarbons, such as dibenzyltoluene. Water or air is most preferred as the heat transfer medium, with water being particularly preferred.

[0130] According to the invention, bottom evaporators are arranged at the bottom of the respective rectification column RD A or reaction column RR A or RR B or RR C arranged and are then referred to as “V S RD" or "V S RD'" or "V SA ' or 'V SA'“ or “V S B" or "V S B'" or "V S c" or "V S c'“. In such a bottom evaporator, a column (especially reaction column RR) A or RRB) bottom product stream (especially S AP or S B p) and, for example, methanol is at least partially removed from it. In the case of S AP or S BP This allows a bottom product stream S AP - with an opposite S AP increased mass fraction of MAOCH3 or a bottom product stream S BP « with an opposite S BP increased mass fraction of MBOCH3 can be obtained.

[0131] In step (a1) of the process according to the invention, at the lower end of the reaction column RR A a bottom product stream S AP comprising methanol and MAOCH3.

[0132] It is preferred that the reaction column RR Aat least one sump evaporator V SA through which the bottom product stream S AP is then partially passed through and methanol is partially removed therefrom, resulting in a bottom product stream S AP - with an opposite S AP increased mass fraction of MAOCH3 is obtained.

[0133] In another preferred embodiment, therefore, for the transfer of energy, preferably heat, from at least a part of a heat carrier, wherein the heat carrier is selected from W*2, W*3, W*4, preferably from W*3, W*4, more preferably W*4, to the crude product RP A and, if step (a2) is carried out, alternatively or additionally on the crude product RPB, proceed as follows:

[0134] In particular, a part of the heat transfer medium in question is then selected from W*2, W*3, W*4, at least partially via a sump evaporator V SA or V SB and the energy from the respective heat carrier selected from W*2, W*3, W*4 to the bottom product stream S AP or S BP transferred, in particular in which the heat transfer medium in question is selected from W*2, W*3, W*4 for heating the evaporator V SA or V S B. The mass fraction of MAOCHS in the bottom product stream S AP - is particularly important compared to the mass fraction of MAOCHS in the bottom product stream S AP increased by at least 0.5%, preferably by > 1%, more preferably by > 2%, even more preferably by > 5%,

[0135] Preferably, S AP or, if at least one sump evaporator V SA is used, through which the bottom product stream S AP is at least partially passed through and methanol is at least partially removed therefrom, S AP«, a mass fraction of MAOCHS in methanol in the range of 1 to 50 wt.%, preferably 5 to 35 wt.%, more preferably 15 to 35 wt.%, most preferably 20 to 35 wt.%, in each case based on the total mass of S AP or S AP «.

[0136] The mass fraction of residual water in S AP or S AP - is preferably < 1 wt.%, preferably < 0.8 wt.%, more preferably < 0.5 wt.%, based on the total mass of S AP or S A p«.

[0137] The mass fraction of reactant MAOH in S AP or S AP - is preferably < 1 wt.%, preferably < 0.8 wt.%, more preferably < 0.5 wt.%, based on the total mass of S A p or S A p«.

[0138] 4.2 Step (a2) (optional)

[0139] Step (a2) is an optional embodiment of the method according to the invention. This means that, within the scope of the preferred embodiment of the method according to the invention, step (a2) is carried out or not.

[0140] In the optional step (a2), simultaneously with and spatially separated from step (a1), a reactant stream SBEI comprising methanol is reacted with a reactant stream S B E2 comprising MBOH in countercurrent in a reactive rectification column RR B to a raw product RP B comprising MBOCHS, water, methanol, MBOH.

[0141] In optional step (a2) of the process according to the invention, at the lower end of RR B a bottom product stream S BP comprising methanol and MBOCHS. At the upper end of RR B becomes a vapor stream S BB comprising water and methanol.

[0142] MB is selected from sodium, potassium, and lithium. MB is particularly selected from sodium and potassium. Preferably, MB = potassium.

[0143] The reactant stream S BEi comprises methanol. In a preferred embodiment, the mass fraction of methanol in S BEi at > 95 wt.%, more preferably at > 99 wt.%, where S BEi otherwise, in particular, water. The methanol used as reactant stream SBEI in optional step (a2) of the process according to the invention can also be commercially available methanol with a methanol mass fraction of more than 99.8 wt. % and a water mass fraction of up to 0.2 wt. %.

[0144] The reactant stream SBEI is preferably added in vapor form.

[0145] The reactant stream S BE 2 comprises MBOH. In a preferred embodiment, S comprises BE 2 in addition to MBOH, at least one further compound selected from water, methanol. More preferably, S comprises BE2besides MBOH also water, then S BE2 an aqueous solution of MBOH.

[0146] If the reactant stream S BE2 MBOH and water, the mass fraction of MBOH, based on the total weight of the aqueous solution, which S BE2 forms, in particular in the range from 10 to 75 wt.%, preferably from 15 to 54 wt.%, more preferably from 30 to 53 wt.% and particularly preferably from 40 to 52 wt.%.

[0147] If the reactant stream S BE2 MBOH and methanol, the mass fraction of MBOH in methanol, based on the total weight of the solution, which S BE2 forms, in particular in the range from 10 to 75 wt%, preferably from 15 to 54 wt%, more preferably from 30 to 53 wt%, and particularly preferably from 40 to 52 wt%.

[0148] In the special case where the reactant stream S BE2in addition to MBOH, it is particularly preferred that the mass fraction of MBOH in methanol and water, based on the total weight of the solution, which S BE2 forms, in particular in the range from 10 to 75 wt.%, preferably from 15 to 54 wt.%, more preferably from 30 to 53 wt.%, and particularly preferably from 40 to 52 wt.%.

[0149] The optional step (a2) of the process according to the invention is carried out in a reactive rectification column (or “reaction column”) RR B Preferred embodiments of the reaction column RR B are described in section 4.1.

[0150] The “conversion of a reactant stream SBEI comprising methanol with a reactant stream SBE2 comprising M B OH in countercurrent” is ensured according to the invention in particular by the fact that the feed point of at least part of the reactant stream S BEicomprising methanol in the optional step (a2) at the reaction column RR B below the inlet point of the reactant stream S BE2 encompassing MBOH.

[0151] The reaction column RR B preferably comprises at least 2, in particular 15 to 40 theoretical stages between the feed point of the reactant stream S BEi and the feed point of the reactant stream S BE2 . The reaction column RR B can be operated as a pure stripping column. Then, in the lower section of the reaction column RR B vaporous reactant stream S BEi extensively supplied with methanol.

[0152] The optional step (a2) also includes the case that part of the reactant stream S BEi comprising methanol below the feed point of the reactant stream S BE2 comprising MBOH, but still at the top or in the region of the top of the reaction column RR BThis allows the dimensions in the lower section of the reaction column RR B If part of the reactant stream S BEi comprising methanol at the top or in the region of the top of the reaction column RR B in particular in vaporous form, only a partial amount of 10 to 70 wt.%, preferably 30 to 50 wt.% (in each case based on the total amount of methanol used in step (a2)) is added at the lower end of the reaction column RR B and the remaining portion is distributed in a single stream or over several partial streams, preferably 1 to 10 theoretical stages, particularly preferably 1 to 3 theoretical stages below the feed point of the reactant stream S BE2 comprising MBOH was added in vapor form.

[0153] In the reaction column RR B the reactant stream S BEi comprising methanol with the reactant stream S BE2comprising MBOH according to the reaction described above <1> to MBOCHS and H2O, whereby, since this is an equilibrium reaction, these products are present in a mixture with the reactants methanol and MBOH. Accordingly, in the optional step (a2) of the process according to the invention, in the reaction column RR B a raw product RP B which, in addition to the products MBOCHS and water, also includes methanol and MBOH.

[0154] At the lower end of RR B The bottom product stream S is then obtained and removed BP comprising methanol and MBOCHS.

[0155] At the top of RR B , preferably at the column head of RR B , the stream of methanol still containing water, referred to above as “vapor stream S BB comprising water and methanol”.

[0156] This vapor stream S BBcomprising water and methanol is in step (a3) ​​at least partially introduced into a rectification column RD A and there distilled at least partially into a vapor stream S OA comprising methanol, which is at the upper end of RD A is taken, and at least one current S UA comprising water, which is at the lower end of RD A Part of the product obtained during the distillation in step (a3) ​​in stream S OA The methanol obtained can be added to the reaction column RR B as reactant stream S BEi In step (a3) ​​of the process according to the invention, when step (a2) is carried out, at least a portion of the vapor stream SBB, mixed with SAB or not (then separated from SAB), is fed into the rectification column RD A Preferably, in step (a3) ​​of the process according to the invention, the vapor streams SBB and SAB are mixed and then the mixture is fed into the rectification column RDA led.

[0157] The amount of methanol comprised in the reactant stream SBEI is preferably selected so that it simultaneously serves as a solvent for the methanol contained in the bottom product stream S B p obtained alkali metal methoxide MBOCHS is used. Preferably, the amount of methanol in the reactant stream SBEI SO is selected so that the desired concentration of the alkali metal methoxide solution is present in the bottom of the reaction column, which is the bottom product stream S B p comprising methanol and MBOCHS.

[0158] In a preferred embodiment of the method according to the invention, and in particular in cases where S B E2 comprises water in addition to MBOH, the ratio of the total weight (mass; unit: kg) of methanol used in optional step (a2) as reactant stream SBEI to the total weight (mass; unit: kg) of methanol used in optional step (a2) as reactant stream S BE2 used MBOH 4 : 1 to 50 : 1 , more preferably 8 : 1 to 48 : 1 , even more preferably 10 : 1 to 45 : 1 , even more preferably 20 : 1 to 40 : 1 , most preferably 22 : 1 .

[0159] The reaction column RR B is operated with or without, preferably with return.

[0160] In the embodiment in which the reaction column RR B a return flow is set, the reactant stream S in the optional step (a2) B E2, the MBOH used can also be at least partially mixed with the recycle stream and the resulting mixture can thus be fed to the optional step (a2).

[0161] The optional step (a2) is carried out in particular at a temperature in the range from 45 °C to 150 °C, preferably 47 °C to 120 °C, more preferably 60 °C to 110 °C, and at a pressure of 0.5 bar abs. to 40 bar abs., preferably in the range from 0.7 bar abs. to 5 bar abs., more preferably in the range from 0.8 bar abs. to 4 bar abs., more preferably in the range from 0.9 bar abs. to 3.5 bar abs., even more preferably at 1.0 bar abs. to 3 bar abs., most preferably at 1.25 bar abs.

[0162] The reaction column RR B In a preferred embodiment, comprises at least one evaporator, which in particular consists of intermediate evaporators VZB and bottom evaporators V S B is selected. The reaction column RR B particularly preferably comprises at least one bottom evaporator V S B.

[0163] In such an intermediate evaporator VZB, in the reaction column RR B liquid raw product RP Bcomprising MBOCHS, water, methanol, MBOH are converted into the gaseous state, and thus the efficiency of the reaction in the optional step (a2) of the process according to the invention is improved.

[0164] By arranging one or more intermediate evaporators VZB in the upper part of the reaction column RR B the dimensions in the lower part of the reaction column RR B In the embodiment with at least one, preferably several, intermediate evaporators V ZB it is also possible to use partial streams of methanol in liquid form in the upper part of the reaction column RR B to supply.

[0165] In the optional step (a2) of the process according to the invention, at the lower end of the reaction column RR B a bottom product stream S BP comprising methanol and MBOCHS.

[0166] It is preferred that the reaction column RR Bat least one sump evaporator V SB through which the bottom product stream S BP is then at least partially passed and methanol is at least partially removed therefrom, whereby a bottom product stream S BP « with an opposite S BP increased mass fraction of MBOCHS is obtained.

[0167] The mass fraction of MBOCHS of the bottom product stream S BP - is particularly important compared to the mass fraction of MBOCHS in the bottom product stream S BP increased by at least 0.5%, preferably by > 1%, more preferably by > 2%, even more preferably by > 5%.

[0168] Preferably, S BP or, if at least one sump evaporator V SB is used, through which the bottom product stream S BP is at least partially passed through and methanol is at least partially removed therefrom, S BP«, a mass fraction of MBOCHS in methanol in the range of 1 to 50 wt.%, preferably 5 to 35 wt.%, more preferably 15 to 35 wt.%, most preferably 20 to 35 wt.%, in each case based on the total mass of S BP or S BP «.

[0169] The mass fraction of residual water in S BP or S BP « is preferably < 1 wt.%, preferably < 0.8 wt.%, more preferably < 0.5 wt.%, based on the total mass of S BP or S BP «.

[0170] The mass fraction of reactant MBOH in S BP or S BP « is preferably < 1 wt.%, preferably < 0.8 wt.%, more preferably < 0.5 wt.%, based on the total mass of S BP or S BP «.

[0171] In the embodiments of the present process in which step (a2) is also carried out, the bottom product stream S APat least partially passed through a bottom evaporator VSA and methanol from S AP at least partially removed, resulting in a bottom product stream S AP - with an opposite S AP increased mass fraction of MAOCHS is obtained and / or, preferably and, the bottom product stream S B p at least partially passed through a bottom evaporator VSB and methanol from S B p at least partially removed, resulting in a bottom product stream S BP « with an opposite S BP increased mass fraction of MBOCHS is obtained.

[0172] In the embodiments of the present invention in which it is carried out, step (a2) of the process according to the invention is carried out simultaneously with and spatially separated from step (a1). The spatial separation is achieved by carrying out steps (a1) and (a2) in the two reaction columns RR A and RR B guaranteed.

[0173] In an advantageous embodiment of the invention, the reaction columns RR A and RR B accommodated in a column shell, the column being at least partially divided by at least one dividing wall. Such a column having at least one dividing wall is referred to as a "TRD." Such dividing wall columns are known to the person skilled in the art and are described, for example, in US 2,295,256, EP 0 122 367 A2, EP 0 126 288 A2,

[0174] WO 2010 / 097318 A1 and by I. Dejanovic, Lj. Matijasevic, Z. Olujic, Chemical Engineering and Processing 2010, 49, 559-580. CN 105218315 A also describes dividing wall columns used in the rectification of methanol.

[0175] In the dividing-wall columns suitable for the process according to the invention, the dividing walls preferably extend all the way to the bottom and particularly preferably span at least a quarter, more preferably at least a third, even more preferably at least half, even more preferably at least two-thirds, and even more preferably at least three-quarters of the column lengthwise. They divide the column into at least two reaction spaces in which spatially separate reactions can take place. The reaction spaces created by the at least one dividing wall can be of the same or different sizes.

[0176] In this embodiment, the bottom product streams S AP and S BP be removed separately and preferably via the bottom evaporator V attached to each reaction chamber formed by the at least one reaction wall SA or V SBin which methanol from S AP or S BP is at least partially removed, whereby S AP - or S BP « can be obtained.

[0177] In a preferred embodiment of the process according to the invention, at least two, more preferably exactly two, of the columns are selected from rectification column RD A , reaction column RR A and, if step (a2) is carried out, the reaction column RR B housed in a column shell, with the columns at least partially separated from each other by a dividing wall extending to the bottom of the column. In a combination of reaction column RR A [or in the embodiments in which step (a2) is carried out, reaction column RR A and reaction column RR B ] with rectification column RD A In the process according to the invention, the rectification column RD Apreferably operated at a pressure chosen so that the pressure gradient between the columns is small.

[0178] In the process according to the invention, the methanol is consumed and, particularly in the case of continuous operation, it must therefore be replaced by fresh methanol.

[0179] The fresh methanol is supplied directly as reactant stream S AEi comprising methanol into the reaction column RR A or in the embodiments in which step (a2) is carried out, into the reaction columns RR A and RR B .

[0180] In the process according to the invention, it is further preferred to process the vapor stream S comprising methanol OA partly as reactant stream S AEi in step (a1) and, if step (a2) is carried out, alternatively or additionally as reactant stream S BEiin step (a2). In this preferred embodiment, it is even more preferred if the fresh methanol of the rectification column RD A is added.

[0181] When the fresh methanol from the rectification column RD A is added, it is preferably added either in the rectification section of the rectification column RD A or directly at the top of the rectification column RD A The optimal feed point depends on the water content of the fresh methanol used and on the desired residual water content in the vapor stream S OA The higher the water content in the methanol used and the higher the purity requirement in the vapor stream S OA is, the more favorable is an inflow a few theoretical stages below the top of the rectification column RD A . Up to 20 theoretical stages below the top of the rectification column RD are preferred Aand in particular 1 to 5 theoretical levels.

[0182] When the fresh methanol from the rectification column RD A is added, it is heated at temperatures up to the boiling point, preferably at room temperature, at the top of the rectification column RD A A separate feed can be provided for the fresh methanol or fresh methanol can be added after condensation and recycling of a portion of the methanol at the top of the rectification column RD A methanol extracted and mixed with it and together fed into the rectification column RD A In this case, it is particularly preferred if the fresh methanol is fed into a condensate tank in which the methanol from the vapor stream S OA condensed methanol is collected.

[0183] As described above, in an advantageous embodiment of the invention, at least two of the columns are selected from rectification column RD A, reaction column RR A and, if step (a2) is carried out, the reaction column RR B accommodated in a column shell, wherein the columns are at least partially separated from one another by a dividing wall extending to the bottom of the column. In the preferred embodiment described above, in which step (a2) is carried out, these are accordingly separated from one another by two dividing walls, wherein the two dividing walls extend to the bottom of the column.

[0184] In this preferred embodiment, in particular in a part of the TRD, the reaction to the crude product RP A according to step (a1) or the raw products RP A and RP B according to steps (a1) and (a2), wherein the reactant stream S AE 2 and optionally the reactant stream S B E2 is added below, but approximately at the level of the upper end of the dividing wall and the reactant stream S AEiand optionally the reactant stream S BEi in vapor form at the lower end. The methanol / water mixture formed above the feed point of the reactant stream is then distributed above the dividing wall over the entire column section, which serves as the rectification section of the rectification column RD A The second or third lower part of the column, separated by the dividing wall, is the stripping section of the rectification column RD A . The energy required for distillation is then supplied via an evaporator at the lower end of the second part of the column separated by the dividing wall, whereby this evaporator can be heated conventionally or with a part of the compressed vapor stream S OA2 If the evaporator is heated conventionally, an intermediate evaporator can be provided, which is heated with a part of the compressed heat transfer medium, e.g. W* 3i orW*4, is heated.

[0185] In the embodiments in which a part of S OA as reactant stream S AEi and / or reactant stream S BEi is used, S OA especially with a compressor VD AB2 compressed, whereby the difference in pressures within the reaction columns RR A and RR B compared to the pressure in RD A can be taken into account.

[0186] Alternatively or additionally, in this preferred embodiment, instead of the compressor VD AB2 , of the rectification column RD A is connected downstream and in the S OA is compressed, a rectification column RD A upstream compressor VD ABi be used, with which S AB , S BB , or the mixture of S AB and S BB before the respective current in RD A is directed, is compressed.

[0187] 4.3 Step (a3)

[0188] In step (a3) ​​of the process according to the invention, at least a part of the vapor stream S AB , and, when step (a2) is carried out, at least a part of the vapor stream S BB , mixed with S AB or separately from S AB , into a rectification column RD A managed and in RD A into at least one vapor stream S OA comprising methanol, which is at the upper end of RD A is taken, and at least one current S UA comprising water, which is at the lower end of RD A In the embodiments of the invention in which step (a2) is carried out, it is preferred if in step (a3) ​​the at least part of the vapor stream SAB and the at least part of the vapor stream SBB are mixed and then fed into a rectification column RD A Alternatively, SAB and SBB can also be fed into the rectification column RD at two different feed pointsA be directed.

[0189] In step (a3) ​​of the process according to the invention, at least a portion of the vapor stream SAB and, when step (a2) is carried out, at least a portion of the vapor stream SBB, mixed with SAB or separated from SAB, is introduced into a rectification column RD A managed and in RD A into at least one vapor stream S OA comprising methanol, which is at the upper end of RD A and at least one stream SUA comprising water, which is taken at the lower end of RD A is taken, separated.

[0190] “At least one vapour stream SOA comprising methanol taken off at the top of RDA” means that the vapour taken off at the top of RD A obtained, can be withdrawn there as one or more vapor streams. If it is withdrawn there in more than one vapor stream, the m vapor streams are referred to as "vapor stream SOAI", "vapor stream SOAII", [...], "vapor stream SO Am”, where “m” is the number of the upper end of RD A extracted vapor streams (in Roman numerals).

[0191] “At least one stream SUA comprising water taken at the lower end of RDA” means that water taken at the lower end of RD A obtained, can be taken there as one or more streams. If it is taken there in more than one stream, the n streams are referred to as "Stream SUAI", "Stream SUAII", [...], "Stream SuAn", where "n" is the number of streams at the lower end of RD A currents drawn (in Roman numerals).

[0192] The at least one part of the vapor stream SAB, and, if step (a2) is carried out, the at least one part of the vapor stream SBB can be fed via one or more feed points into the rectification column RD AThey are passed through several feed points, for example in the embodiments in which step (a2) is carried out in the process according to the preferred aspect of the invention and in step (a3) ​​at least a portion of the vapor stream SBB is used separately from SAB. In this embodiment, the at least a portion of the vapor stream SAB and the at least a portion of the vapor stream SBB are accordingly fed as two separate streams into the rectification column RD A led.

[0193] In the embodiments of the present invention in which the at least part of the

[0194] vapor stream SAB, and, when step (a2) is carried out, at least part of the

[0195] If the vapor stream SBB is or are fed into the rectification column RDA as two or more separate streams, it is advantageous if the feed points of the individual streams are essentially at the same height on the rectification column RD A lay.

[0196] In a preferred embodiment of step (a3) ​​of the process according to the invention, at least one part of the vapor stream SAB and, when step (a2) is carried out, at least one part of the vapor stream SBB are rectified in the rectification column RD A into a vapor stream S OA comprising methanol, which is at the upper end of RD A and a stream SUA comprising water, which is taken from the lower end of RD A is taken, separated.

[0197] Another term for “top of a rectification column” is “head”.

[0198] Another term for “lower end of a rectification column” is “sump” or “foot”.

[0199] The pressure of at least one vapor stream S OA is designated as "POA" and its temperature as "TOA". This refers in particular to the pressure and temperature of at least one vapor stream S OA , if it is in step (a3) ​​of the rectification column RD A is taken.

[0200] The pressure p OA is in particular in the range from 0.5 bar abs. to 8 bar abs., more preferably in the range from 0.6 bar abs. to 7 bar abs., more preferably in the range from 0.7 bar abs. to 6 bar abs., even more preferably in the range from 1 bar abs. to 5 bar abs., even more preferably in the range from 1 bar abs. to 4 bar abs., even more preferably in the range from 1.0 to 2.0 bar abs., and is most preferably 1.1 bar abs.

[0201] The temperature TOA is in particular in the range of 45 °C to 150 °C, more preferably in the range of 48 °C to 140 °C, more preferably in the range of 50 °C to 130 °C, even more preferably in the range of 60 °C to 120 °C, even more preferably in the range of 60 °C to 110 °C, even more preferably in the range of 65 °C to 80 °C, most preferably 67 °C.

[0202] As rectification column RD AIn step (a3) ​​of the process, any rectification column known to the person skilled in the art can be used. The rectification column preferably contains RDA internals. Suitable internals include, for example, trays, unstructured packings, or structured packings. Trays typically used are bubble-cap trays, sieve trays, valve trays, tunnel trays, or slotted trays. Unstructured packings are generally random packings. Raschig rings, Pall rings, Berl saddles, or Intalox® saddles are typically used as packings. Structured packings are marketed, for example, under the trade name Mellapack® by Sulzer. In addition to the internals mentioned, other suitable internals are known to the person skilled in the art and can also be used.

[0203] Preferred internals exhibit a low specific pressure drop per theoretical plate. Structured packings and random packings, for example, have a significantly lower pressure drop per theoretical plate than trays. This has the advantage that the pressure drop in the rectification column RD A remains as low as possible and thus the mechanical power of the compressor and the temperature of the methanol / water mixture to be evaporated remain low.

[0204] If in the rectification column RD A If structured or unstructured packages are included, these may be divided or there may be a continuous package. However, at least two packages are usually provided:

[0205] 1) If step (a2) is not carried out, it is preferred that: a packing above the inlet point of S AB ; if step (a2) is executed and S AB and S BBmixed and then in RD A be routed: one packing above the inlet point of the mixture of S AB and S BB ; if step (a2) is executed and S AB and S BB separated into RD A be routed: a packing above the inlet points of S AB and S BB .

[0206] 2) It is also preferred: if step (a2) is not carried out: a packing below the inlet point of S AB ; if step (a2) is executed and S AB and S BB mixed and then in RD A be routed: one packing below the inlet point of the mixture of S AB and S BB ; if step (a2) is executed and S AB and S BB separated into RD A be routed: one packing below the inlet points of S AB and S BB .

[0207] A pack can also be installed above the inlet point of SAB or S AB and S BB and several floors below the inlet point of S AB or S AB and S BB If an unstructured packing is used, for example a random packing, the packing elements are usually supported on a suitable support grid (e.g. sieve or grid).

[0208] It is preferred in the respective embodiment that the feed point of S AB or S AB and S BB in the lower half of the column RD A is, that is, S AB or S AB and S BB into the lower half of the column RD A be directed.

[0209] In step (a3) ​​of the process according to the invention, the at least one vapor stream S OA comprising methanol at the top of the rectification column RD A The preferred mass fraction of methanol in this vapor stream S OAis > 99 wt%, more preferably > 99.6 wt%, even more preferably > 99.9 wt%, the remainder being water.

[0210] At the lower end of RD A at least one current S UA comprising water, which may preferably contain < 1 wt.%, more preferably < 5000 wt. ppm, even more preferably < 2000 wt. ppm of methanol.

[0211] The withdrawal of at least one vapor stream S OA comprising methanol at the top of the

[0212] Rectification column RD A In the context of the present invention, means in particular that the at least one vapor stream S OA as top stream or as side draw above the internals in the rectification column RD A is taken.

[0213] The withdrawal of at least one current S UA comprising water at the bottom of the rectification column RD AIn the context of the present invention, means in particular that the at least one stream S UA as bottom stream or at the bottom of the rectification column RD A is taken.

[0214] The rectification column RD A is operated with or without, preferably with return.

[0215] “With reflux” means that the reflux at the top of the rectification column RD A extracted vapor stream S OA is not completely discharged, but partially condensed and returned to the respective rectification column RD A In cases where such a reflux is established, the reflux ratio is preferably 0.0001 to 10, more preferably 0.1 to 5, even more preferably 0.5 to 2, even more preferably 0.7 to 1, even more preferably 0.76.

[0216] A reflux can be set by placing at the top of the rectification column RD A a capacitor K RDis attached. In the capacitor K RD the vapor stream S OA partially condensed and the rectification column RD A fed back in. A reflux ratio is generally understood, and within the meaning of this invention, to be the ratio of the proportion of the mass flow (kg / h) withdrawn from the column that is returned to the column in liquid form (reflux) to the proportion of this mass flow (kg / h) that is discharged from the respective column in liquid or gaseous form.

[0217] 4.4 Step (b) of the process according to the invention

[0218] In step (b) of the process according to the invention, at least one side stream SZÄ from RD A removed and returned to RD A returned.

[0219] In a preferred embodiment of step (b) of the process according to the invention, a side stream SZÄ from RD A removed and returned to RD Areturned.

[0220] “Side stream SZÄ from RD A “ means according to the invention that the flow at a withdrawal point EZÄ is below the head and above the sump of RD A and in particular additionally at a feed point ZZÄ (this is the point at which the respective side stream SZÄ is fed back into the rectification column RD A is returned) below the head and above the sump of RD A back in RD A is returned.

[0221] This means in particular that the withdrawal point EZÄ, and preferably also the feed point ZZÄ of the respective side stream SZÄ at the rectification column RD A below the EOA sampling points of all from RD A extracted vapor streams S OA is preferably at least 1, more preferably at least 5, more preferably at least 10 theoretical stages below the withdrawal point E OA that from RD Aextracted vapor stream S OA , whose sampling point E OA furthest down the rectification column RD A lies, lies.

[0222] This also means in particular that the withdrawal point EZA, and preferably also the feed point ZZA of the respective side stream SZA at the rectification column RD A above the extraction points E UA all from RD A withdrawn currents S UA is preferably at least 1, more preferably at least 2, more preferably at least 4 theoretical stages above the withdrawal point E UA of the current S UA , whose sampling point E UA at the top of the rectification column RD A lies, lies.

[0223] In cases where at least one vapor stream S OA at least partially back into the rectification column RD Ais recycled (which is the case, for example, if a reflux at the rectification column RD A is set), in particular the inlet point Z OA (this is the point where at least one vapor stream S OA at least partially back into the rectification column RD A is recycled) of at least one vapor stream S OA above the EZA withdrawal points and especially above the ZZA inlet points of all RD A withdrawn side streams SZA, preferably at least 1, more preferably at least 5, even more preferably at least 10 theoretical stages above the highest point of all withdrawal and feed points of all from RD A taken side streams SZA.

[0224] In cases where at least one current S UA at least partially back into the rectification column RD A is returned, in particular the inlet point Z UA(this is the point where at least one current S UA at least partially back into the rectification column RD A is returned) of at least one current S UA below the EZA withdrawal points and especially below the ZZA inlet points of all RD A withdrawn side streams SZA, preferably at least 1, more preferably at least 2, even more preferably at least 4 theoretical stages below the lowest point of all withdrawal and feed points of all from RD A taken side streams SZA.

[0225] The withdrawal point EZA of the side stream SZA and the feed point ZZA of the side stream SZA at the rectification column RD A can be used between the same floors of RD A positioned. However, it is also possible that they are at different heights.

[0226] In a preferred embodiment of the process according to the invention, the withdrawal point EZA and preferably also the feed point ZZA of the at least one side stream SZA are located on the rectification column RD A below the inlet point Z SA B, and above the swamp of RD A . Even more preferably, the withdrawal point EZA and preferably also the feed point ZZA of the at least one side stream SZA are located on the rectification column RD A also below the amplifier part of RD A .

[0227] The inlet point Z SA B denotes the lowest inlet point of all inlet points of S AB in RD A , all SBB access points in RD A , and all inlet points of the mixture of S AB and SBB in RD A .

[0228] In a particularly preferred embodiment of the process according to the invention, the withdrawal point EZA and more preferably also the feed point ZZA of the at least one side stream SZA are located on the rectification column RD A in the upper 4 / 5, preferably upper 3 / 4, preferably upper 7 / 10, more preferably upper 2 / 3, more preferably upper 1 / 2 of the area on the rectification column RD A , which is below the inlet point Z SA B, and above the highest of all withdrawal and inlet points of all from RD A withdrawn currents S UA lies.

[0229] Even more preferably, the withdrawal point EZA and preferably also the feed point ZZA of the at least one side stream SZA are located on the rectification column RD A then also below the amplifier part of RD A .

[0230] In a further particularly preferred embodiment of the process according to the invention, the rectification column RD Aan amplifier section, and the withdrawal point EZA and preferably also the feed point ZZA of at least one side stream SZA is located on the rectification column RD A in the upper 4 / 5, preferably upper 3 / 4, preferably upper 7 / 10, more preferably upper 2 / 3, more preferably upper 1 / 2 of the area on the rectification column RD A , which is located below the amplifier section and above the top of all the withdrawal and inlet points of all from RD A withdrawn currents S UA lies.

[0231] 4.5 Step (c) of the process according to the invention

[0232] In step (c) of the process according to the invention, energy, preferably heat, is extracted from at least a portion of S OA transferred to a liquid or gaseous, preferably liquid, heat carrier W*i, whereby a gaseous heat carrier W*2 is obtained.

[0233] Any working medium familiar to the person skilled in the art can be used as the heat transfer medium W*i. The heat transfer medium W*i is in particular selected from the group consisting of water, optionally fluorinated alkanes, ammonia, and alcohols. W*i is preferably selected from n-hexane, n-pentane, n-butane, n-propane, methanol, ethanol, and propanol. W*i is most preferably n-butane.

[0234] By step (c) of the process according to the invention, energy, preferably heat, is extracted from at least a part of S OA transferred to the liquid or gaseous, preferably liquid, heat carrier W*i, thereby obtaining the gaseous heat carrier W*2. This means that if the heat carrier W*i is used in liquid form in step (c), energy, preferably heat, is supplied to it in step (c) so that the liquid heat carrier W*i at least partially evaporates, thereby obtaining a gaseous heat carrier W*2.

[0235] “Liquid heat transfer medium W*i” means in particular that > ​​10 wt.% of the heat transfer medium W*i used in step (c) is in the liquid state, based on the total weight of the heat transfer medium W*i used in step (c). Preferably, it means that

[0236] > 25 wt.%, more preferably > 50 wt.%, more preferably > 55 wt.%, more preferably > 75 wt.%, more preferably e 90 wt.%, more preferably e 99 wt.% of the heat transfer medium W*i used in step (c) is in the liquid state, based on the total weight of the heat transfer medium W*i used in step (c).

[0237] If a liquid heat transfer medium W*i is used in step (c) of the process according to the invention, in a preferred embodiment, so much energy, preferably heat, is transferred from at least a part of SOA to the liquid heat transfer medium W*i in step (c) of the process according to the invention that during step (c) > 10 wt.%, preferably

[0238] > 20 wt.%, preferably > 30 wt.%, preferably > 40 wt.%, preferably > 50 wt.%, preferably

[0239] > 60 wt.%, preferably > 70 wt.%, preferably > 80 wt.%, preferably > 90 wt.%, preferably

[0240] > 99 wt.% of the heat transfer medium W*i used in the liquid state is converted into the gaseous state, particularly preferably that during step (c) the liquid heat transfer medium W*i is completely converted into the gaseous state.

[0241] Alternatively, the heat transfer medium W*i can be used in gaseous form in step (c). Since energy, preferably heat, is added to it in step (c), a gaseous heat transfer medium W*2 is then obtained again following step (c).

[0242] “Gaseous heat transfer medium W means in particular that the heat transfer medium W*i used in step (c) is entirely in the gaseous state.

[0243] According to the invention, “transfer of energy” means in particular “heating”, i.e. transfer of energy in the form of heat.

[0244] "Transfer of energy, preferably heat, from at least a part of SOA to a liquid or gaseous, preferably liquid, heat carrier W*T also includes the embodiments of step (c) in which SOA is first divided, for example into a part SOAI which, optionally after compression of this part S O AI , as methanol stream SAEI and / or SBEI is used, and a part S O A2, which serves as return to the column RD A is returned, whereby only S O A2 Energy, especially heat, is transferred to W*i. W*2 has a higher energy content than W*i. In contrast, the energy content of SOA decreases during step (c).

[0245] The transfer of energy, in particular heat, from at least a portion of the SOA to the liquid or gaseous, preferably liquid, heat transfer medium W*i preferably occurs directly or indirectly, more preferably directly. Another term for "heat transfer" is "heating."

[0246] “Direct” means in particular that SOA is contacted with W*i without SOA and W*i mixing, so that energy, especially heat, is transferred from SOA to W*I.

[0247] This can be done using methods known to those skilled in the art.

[0248] In particular, SOA and W*i can be passed through a heat exchanger in which energy, preferably heat, is transferred from SOA to W*I.

[0249] Heat exchangers (another term for “heat exchanger”) can be those familiar to the person skilled in the art, in particular evaporators, in particular boiler evaporators, as described above (under point 4.1).

[0250] A boiler evaporator is preferably used in which W*i is expanded and then or during this time absorbs energy from SOA.

[0251] As described above, in a preferred embodiment of the present invention, at the rectification column RD A a reflux is set, whereby in particular at the top of the rectification column RD A a capacitor K RD in which the vapor stream SOA is partially condensed and the rectification column RD A is fed back in.

[0252] In this preferred embodiment, the direct transfer of energy, preferably heat, from SOA to W*I is achieved, particularly in the capacitor K RD This has the advantage that the capacitor K RD at the same time as heat transfer it can be used and no additional evaporator / condenser needs to be installed.

[0253] “Indirect” means in particular that SOA is heated with a heat carrier Wi* different from W*i, preferably via at least one heat exchanger WT X, is contacted, whereby the heat carrier Wi* is not W*i, i.e. Wi* is different from W*i, so that energy, preferably heat, is transferred from SOA to WI without the two streams mixing, and the heat then transfers from Wi to W, in which the heat carrier Wi* contacts the heat carrier W*i, whereby W*i and Wi* mix or do not mix, but preferably do not mix. If Wi* and W*i do not mix, the transfer of energy, preferably heat, takes place, in particular in a further heat transfer WT Y . In a further embodiment of the method according to the invention, indirect energy transfer from S OA on W*i, in particular heating of W*i by S OA , also initially energy, preferably heat from S OA to Wi*, preferably by contacting via at least one heat exchanger WT Xand then from Wi* to another heat carrier W2* different from W*i, preferably by contacting via at least one heat exchanger WT Y , are transferred. In the last step, the heat is transferred from W2* to W*i, whereby W*i and W2* mix or do not mix, but preferably do not mix. If W2* and W*i do not mix, the energy is transferred, preferably heat, in particular in another heat exchanger WT Z .

[0254] It goes without saying that in further embodiments of the present invention, further heat transfer media W3*, W4*, W5* etc. can be used accordingly.

[0255] Any heat transfer medium known to the person skilled in the art can be used as heat transfer medium Wi* or as additional heat transfer mediums W2*, W3*, W4*, W5*. They are preferably selected from the group consisting of air; water; alcohol-water solutions; salt-water solutions, including ionic liquids such as LiBr solutions, dialkylimidazolium salts such as, in particular, dialkylimidazolium dialkylphosphates; mineral oils such as, for example, diesel oils; thermal oils such as, for example, silicone oils; biological oils such as, for example, limonene; aromatic hydrocarbons such as, for example, dibenzyltoluene. The most preferred heat transfer medium Wi* is water or air, most preferably water.

[0256] As described above, in a preferred embodiment of the present invention, at the rectification column RD A a reflux is set, whereby in particular at the top of the rectification column RD A a capacitor K RDis installed in which the vapor stream S OA partially condensed and the rectification column RD A is fed back in.

[0257] In this preferred embodiment, the direct or indirect transfer of energy, preferably heat, from S OA on W*i or S OA on Wi* especially in capacitor K RD This has the advantage that the capacitor K RD can be used as a heat exchanger at the same time and no additional evaporator / condenser needs to be installed.

[0258] Following step (c) of the process according to the invention, a gaseous heat transfer medium W*2 is obtained.

[0259] The pressure exerted by W*2 is denoted by “pw*2” and its temperature by “Tw*2”.

[0260] The pressure at W*i is denoted by "pw*i" and its temperature by "Tw*i". In a preferred embodiment of the present invention, W*i has a temperature T w *i in the range from 50 °C to 170 °C, more preferably 90 °C, and, especially when W*i is gaseous, a pressure pw*i of 1 bar to 35 bar, more preferably 1.5 bar to 20 bar.

[0261] In a preferred embodiment of the present invention, W*2 has a temperature T w *2 in the range from 25 °C to 150 °C, more preferably 70 °C, and a pressure pw*2 of 1 bar to 35 bar, more preferably 5 bar to 8 bar, even more preferably 6.4 to 6.7 bar.

[0262] It goes without saying that the heat carrier W*2 is the same as the heat carrier W*i and that W*2 and W*i differ only in their respective pressures pw*2 and p w *i and / or its temperature T w *2 or T w*i and, if applicable, when W*i was used as a liquid, differ in their state of aggregation.

[0263] 4.6 Step (d) of the process according to the invention

[0264] In step (d) of the process according to the invention, at least a portion of the gaseous heat transfer medium W*2 is compressed. This results in a gaseous heat transfer medium W*3 that is more compressed than W*2.

[0265] The pressure exerted by W*2 is denoted by “pw*2” and its temperature by “Tw*2”.

[0266] The pressure exerted by W*3 is denoted by “pw*3” and its temperature by “Tw*3”.

[0267] The pressure p w *3 is higher than pw*2. The exact value of pw*3 can be set by the person skilled in the art depending on the requirements in step (d), as long as the condition pw*3> Pw*2 is met. The quotient of p w*3 / Pw*2 (pressures in bar abs.) is preferably in the range from 1.1 to 10, more preferably 1.2 to 8, more preferably 1.25 to 7, more preferably 1.3 to 6, even more preferably 1.5 to 2, even more preferably 1.6 to 1.8, most preferably 1.7.

[0268] The temperature T W *3 is in particular higher than the temperature Tw*2, and the quotient of Tw*3 / Tw*2 (temperature in each case in °C) is preferably in the range from 1.03 to 10, more preferably 1.04 to 9, more preferably 1.05 to 8, more preferably 1.06 to 7, more preferably 1.07 to 6, most preferably 1.08 to 5.

[0269] The preferred values ​​of pw*3 and Tw*3 also apply accordingly to the preferred pressure and temperature of W* 3i and W* 32 .

[0270] The compression of at least a portion of the gaseous heat transfer medium W*2 in step (d) can be carried out in any manner known to the person skilled in the art. For example, the compression can be carried out mechanically and in a single stage or in multiple stages, preferably in multiple stages. In multi-stage compression, several compressors of the same design or compressors of different designs can be used. Multi-stage compression can be carried out with one or more compressor machines. The use of single-stage compression or multi-stage compression depends on the compression ratio and thus on the pressure to which the gaseous heat transfer medium W*2 is to be compressed.

[0271] As a compressor in the process according to the invention, in particular for compressing the gaseous heat carrier W*2to W*3or W* 32To achieve W*4, any compressor known to those skilled in the art, preferably mechanical compressors, with which gas streams can be compressed is suitable. Suitable compressors include single- or multi-stage turbines, piston compressors, screw compressors, centrifugal compressors, or axial compressors.

[0272] In multi-stage compression, suitable compressors are used for each pressure stage to be overcome.

[0273] 4.7 Step (e) of the process according to the invention

[0274] In step (e) of the method according to the invention, energy, in particular heat, is extracted from a first part W* 3i of the gaseous heat carrier W*3 to SZA before SZA in RD A is returned.

[0275] The gaseous heat carrier W*3 is first divided into at least two parts W* 3i and W* 32 The ratio of the mass flows (in kg / h) of W* 3i to W*32 is preferably in the range of 1:99 to 99:1, more preferably in the range of 1:50 to 50:1, even more preferably in the range of 1:20 to 30:1, even more preferably in the range of 5:20 to 15:1, more preferably 2:1 to 5:1, even more preferably 4:1 to 4.5:1, most preferably 4.4:1.

[0276] In step (e) of the process according to the invention, energy is extracted from the first part W* 3i transferred to SZA. Through step (e) the energy of W*3i decreases, so that in particular W* 3i at least partially condensed.

[0277] According to the invention, “transfer of energy” means in particular “heating”, i.e. transfer of energy in the form of heat.

[0278] “Transfer of energy from a first part W*3i of the compressed vapor stream W*3 to SZA” also includes the cases in which a part of W* 3iis separated and only this part of the energy is transferred to SZA. This is the case, for example, in those embodiments of the invention in which additional energy of W* 3i on the raw product RP A and, if step (a2) is carried out, alternatively or additionally to the crude product RP B (described in Section 4.1). The transfer of energy from W* 3i on SZA, prefers heating of SZA by W* 3i is preferably done directly or indirectly.

[0279] “Direct” means that * 3i with SZA without the two currents mixing, so that energy, especially heat, is transferred from * 3i to SZA.

[0280] This can be done by W* 3i and SZA through an intermediate evaporator V Z RD at the rectification column RD A be directed and W* 3i heated the SZA.

[0281] As heat exchangers (another term for “heat exchanger”), in particular as the heat exchangers WT mentioned below X , WT Y , WT Z , heat exchangers familiar to the person skilled in the art, in particular evaporators, can be used. In step (e) of the process according to the invention, the energy, preferably heat, is transferred from * 3i on SZA in an intermediate evaporator V Z RD.

[0282] “Indirect” means in particular that W* 3i with a heat transfer medium W%, preferably via at least one heat transfer medium WT X , where the heat carrier W*i is not SZA, W*i is different from SZA, so that energy, preferably heat, from W* 3ito W*i without the two streams mixing, and the heat then transfers from W*i to SZA, in which W*i contacts the stream SZA, whereby SZA and W*i mix or do not mix, but preferably do not mix. If W*i and SZA do not mix, the transfer of energy, preferably heat, takes place in particular in another heat exchanger WT Y .

[0283] In a further embodiment of the process according to the invention, indirect energy transfer of W* 3i on SZA, especially heating of SZA by W*3i, also initially energy, preferably heat of W* 3i to W*i, preferably by contacting via at least one heat exchanger WT X and then from W*i to another heat carrier W*2, different from SZA, preferably by contacting via at least one heat exchanger WT Y, are transferred. In the last step, the heat is transferred from W*2 to SZA, whereby SZA and W*2 mix or do not mix, but preferably do not mix. If W*2 and SZA do not mix, the energy is transferred, preferably heat, in particular in another heat exchanger WT Z .

[0284] It goes without saying that in further embodiments of the present invention, further heat transfer media W*3, W*4, W*5 etc. can be used accordingly.

[0285] Any heat transfer medium known to the person skilled in the art can be used as heat transfer medium W*i or as additional heat transfer mediums W*2, W*3, W, W*5. They are preferably selected from the group consisting of air, water; alcohol-water solutions; salt-water solutions, which also include ionic liquids, such as LiBr solutions, dialkylimidazolium salts such as, in particular, dialkylimidazolium dialkylphosphates; mineral oils, such as, for example, diesel oils; thermal oils such as, for example, silicone oils; biological oils such as, for example, limonene; aromatic hydrocarbons such as, for example, dibenzyltoluene. The most preferred heat transfer medium W*i is water or air, even more preferably water.

[0286] Salt-water solutions that can be used are also described, for example, in DE 10 2005 028 451 A1 and WO 2006 / 134015 A1.

[0287] In a preferred embodiment, further energy is transferred from W*3i, in particular after the transfer of energy to SZA.

[0288] In a preferred embodiment of the method according to the invention, energy, preferably heat, is extracted from W*3i after W* 3i Energy transferred to SZA in accordance with step (e), to SOA or part of S OA transferred, in particular to the part of S OA , S O AI , which is then subjected to compression, which may be a pre-compression of the part of SOA. This allows a part of the data still available from W* 3i to use the stored residual energy or residual heat in the process, in this case to heat SOA or a part of SOA, SOAT

[0289] “Pre-compaction” refers in particular to the first compaction stage in a multi-stage compaction process.

[0290] Other preferred additional sinks for the energy, preferably heat in W*3i, are described below (see paragraph 4.10).

[0291] Step (e) of the process according to the invention reflects one aspect of the unexpected effect of the present invention. The excess energy obtained during the compression of the gaseous heat carrier W*2 to the compressed gaseous heat carrier W*3 is not dissipated unused, but is used in the rectification. This is done by first compressing \N*2 to W*3, which allows adjustment to the value required for energy transfer from W* 3i on SZA is optimal, and then a function of W* 3i various part W* 32 can be further compressed to W*4. The condensation heat that is released during the further compression of W* 32The resulting W*4 is fed into the column in the bottom evaporator. The required additional compressor power is less than the resulting saved heating steam power. The process according to the invention requires less energy than those of the prior art, as shown in Examples 1 and 2. With the compression to W*4, the pressure and temperature of W*4 can be adjusted so that optimal energy transfer from W*4 to SUAI or SUA can occur. 4.8 Step (f) of the process according to the invention

[0292] In step (f) of the process of the invention, a part of the gaseous heat carrier W*3, W* 32 , is further compressed, resulting in a 3i compressed vapor stream W*4 is obtained.

[0293] It goes without saying that after performing step (f) W*4 also has a value of 0.001 compared to W* 32 and W*3 is compressed.

[0294] The pressure of the vapor stream W*4 is designated as “pw*4” and its temperature as “TW”.

[0295] The pressure p w *4 is higher than p w *3, and the quotient of pw*4 / pw*3 (pressures in each case in bar abs.) is preferably in the range from 1.1 to 10, more preferably 1.2 to 8, more preferably 1.25 to 7, more preferably 1.3 to 6, more preferably 1.4 to 5, more preferably 1.5 to 2, more preferably 1.5 to 1.8, most preferably 1.61.

[0296] The temperature T w *4 is particularly higher than the temperature T w *3and the quotient of Tw*4 / Tw*3 (temperature in each case in °C) is preferably in the range from 1.03 to 10, more preferably 1.04 to 9, more preferably 1.05 to 8, more preferably 1.06 to 7, more preferably 1.07 to 6, most preferably 1.08 to 5.

[0297] The compression of W* 32in step (f) can be carried out using methods familiar to those skilled in the art. For example, the compression can be carried out mechanically in a single-stage or multi-stage manner, preferably in a multi-stage manner. In multi-stage compression, several compressors of the same type or compressors of different types can be used. The use of single-stage compression or multi-stage compression depends on the pressure to which the vapor W* is to be reduced. 32 is to be compressed. The embodiments of compression described in the context of step (d) for W*2 and also the preferred types of compressors can also be used for the compression of W* 32 to W*4, but in particular in step (f) the compression in one stage is sufficient, ie using a compressor VD X .

[0298] 4.9 Step (g) of the process according to the invention

[0299] In step (g) of the process according to the invention, energy is transferred from at least a part of W* 4 to at least a part SUAI of the at least one stream SUA before SUAI is recycled to RDA.

[0300] Preferably, in step (g), energy is transferred from at least a part of W*4 to a part SUAI of the at least one stream SUA before SUAI is converted into RD A is returned.

[0301] Through step (g), the energy of W*4 decreases, so that in particular W*4 is at least partially condensed. Step (g) of the process according to the invention is preferably carried out according to the following

[0302] Embodiments (g1), (g2), (g3) carried out:

[0303] (g1) Energy is transferred from at least a part of W*4 to a part SUAI of at least one stream SUA, and SUAI is then transferred into RD A returned;

[0304] (g2) Energy is transferred from at least a part of W*4 to a part SuAr of at least one current SUA, and from SUAI* a part SUAI is then transferred into RD A returned;

[0305] (g3) Energy is transferred from at least a part of W*4 to the entire stream SUA and then the entire stream SUA or only a part SUAI of the stream SUA, preferably only a part SUAI of the stream SUA, is converted into RD A returned.

[0306] The transfer of energy from at least a part of W*4 to the at least one part SUAI of the at least one stream SUA, preferably the heating of the at least one part SUAI of the at least one stream SUA by at least a part of W*4, preferably takes place directly or indirectly.

[0307] "Direct" means that at least a part of W*4 is contacted with the at least one part SUAI of the at least one stream SUA without the two streams mixing, so that energy, in particular heat, is transferred from at least a part of W*4 to the at least one part SUAI of the at least one stream SUA.

[0308] This can be done by passing the at least one part of W*4 and the at least one part SUAI of the at least one stream SUA through a bottom evaporator V S RD at the rectification column RD A and W*4heats at least a part SUAI of at least one stream SUA.

[0309] As heat exchangers, in particular as the following heat exchangers WT X , WT Y , WT Z, heat exchangers familiar to the person skilled in the art, in particular evaporators, can be used. In step (g) of the process according to the invention, the energy, preferably heat, is transferred from at least a portion of W*4 to at least a portion SUAI of the at least one stream SUA in a bottom evaporator V S RD.

[0310] “Indirect” means in particular that at least one part of W*4 is supplied with at least one heat carrier W'i, preferably via at least one heat exchanger WT X, wherein the heat transfer medium is not the at least one part SUAI of the at least one stream SUA, W'i is therefore different therefrom, so that energy, preferably heat, is transferred from the at least one part of W*4 to the at least one heat transfer medium W'i without the two streams mixing, and the heat is then transferred from W'i to the at least one part SUAI of the at least one stream SUA, in which W'i contacts the stream SUAI, wherein the at least one part SUAI of the at least one stream SUA and W'i mix or do not mix, but preferably do not mix.

[0311] In a further embodiment of the process according to the invention, in the case of indirect energy transfer from at least one part of W*4 to the at least one part SUAI of the at least one stream SUA, in particular heating of the at least one part SUAI of the at least one stream SUA by the at least one part of W*4, energy, preferably heat, can also first be transferred from W*4 to W'i, preferably by contacting via at least one heat exchanger WTx, and then from W'i to a further heat carrier W'2, different from the at least one part SUAI of the at least one stream SUA, preferably by contacting via at least one heat exchanger WT Y , are transferred. In the last step, the heat is then transferred from W"2 to the at least one part SUAI of the at least one stream SUA, wherein the at least one part SUAI of the at least one stream SUA and W"2 may or may not mix, but preferably do not mix.

[0312] It goes without saying that in further embodiments of the present invention, further heat transfer media W'3, W'4, W'5 etc. can be used accordingly.

[0313] Any heat transfer medium known to the person skilled in the art can be used as heat transfer medium W'i or as additional heat transfer mediums W"2, W'3, W'4, W'5. They are preferably selected from the group consisting of air, water; alcohol-water solutions; salt-water solutions, which also include ionic liquids, such as LiBr solutions, dialkylimidazolium salts, such as dialkylimidazolium dialkylphosphates in particular; mineral oils, such as diesel oils; thermal oils such as silicone oils; biological oils such as limonene; aromatic hydrocarbons such as dibenzyltoluene. The most preferred heat transfer medium W'i is water or air, even more preferably water.

[0314] Salt-water solutions that can be used are also described, for example, in DE 10 2005 028 451 A1 and WO 2006 / 134015 A1.

[0315] In a preferred embodiment, following step (g) of at least a part of W*4, in particular after the transfer of the energy to the at least a part SUAI of SUA, further energy is transferred.

[0316] In a preferred embodiment of the method according to the invention, energy, preferably heat, from at least a part of W*4, after W*4 energy has been transferred to the at least a part SUAI of SUA according to step (g), is transferred to S OA or transfer part of SOA, in particular to the part of S OA , S OAI , which is then subjected to compression, which may involve pre-compression of the part of SOA. This allows a portion of the residual energy or residual heat stored by at least one part W*4 to be used in the process, in this case for heating SOA or a portion of SOA, SOAI -

[0317] Following step (g), at least a portion of W*4 can then be re-injected with the heat transfer medium W*3, W*3i, W* obtained after carrying out step (d) or (e) 32 and fed as liquid or gaseous heat transfer medium W*i to a new cycle of the process in step (c). Optionally, W*4 is combined with one of the streams W*3, W* 3i , W* 32 relaxed.

[0318] In a preferred embodiment of the invention, a portion of the heat transfer fluid W*4 obtained after step (g) is also depressurized to a lower pressure via a valve before being fed to a new cycle as W*i. This allows the pressure of W*4 to be reduced to the preferred range of W*i.

[0319] Alternatively or in addition to a valve, energy, in particular heat, can be transferred from at least a part of the heat carrier W*4 obtained after step (g) to \N*2 before W*2 is compressed in step (d).

[0320] Alternatively or additionally, a part of the heat transfer medium W*4 obtained after step (g) can also be expanded through a valve or into a condensate container, and the thus expanded part can then be mixed with W*3, in particular one of the parts W* 3i or W*32 of the gaseous heat carrier W*3.

[0321] Other preferred additional sinks for the energy, preferably heat, in at least a part of W*4 are described below (see paragraph 4.10).

[0322] In a further preferred embodiment, energy is extracted from the bottom product stream S A p and, if step (a2) is carried out, alternatively or additionally from the bottom product stream S B p transferred to SOA or a part of SOA, in particular to the part of SOA, SOAI , which is subjected to compaction, which may be a pre-compaction of the part of SOA.

[0323] In a further preferred embodiment, energy is extracted from the bottom product stream S A p and, if step (a2) is carried out, alternatively or additionally from the bottom product stream S B p is transferred to at least a portion of W*i before W*i is used in step (c). 4.10 Preferred aspect: Process for the transalcoholization of an alkali metal alcoholate

[0324] In an advantageous embodiment of the present invention, the energy contained in at least one of the currents W*3, W*3i, W* 32 , W*4, is used to operate other industrial processes. This is particularly advantageous in integrated sites (chemical parks, technology parks) where there is a constant demand for heating. This energy can be used advantageously, especially in complexes with several plants for alkali metal alkoxide production. Such complexes typically also include processes for transalcoholization, as described in DE 27 26 491 A1. US 3,418,383 A, WO 2021 / 122702 A1 describe processes for transalcoholation from methanolates to propylates.

[0325] In a preferred aspect of the present invention, in the process according to the present invention, in a reactive rectification column RR C a reactant stream S CEI comprising McOR' and optionally R'OH with a reactant stream S C E2 comprising R”OH in countercurrent to a crude product RP C comprising McOR” and R'OH, whereby at the lower end of RR C a bottom product stream S C p comprising McOR” and at the upper end of RR C a vapor stream S C B comprising R'OH, and wherein R' and R" are two different Ci to Ce hydrocarbon radicals, and Mc is a metal selected from lithium, sodium, potassium, preferably sodium, potassium, more preferably sodium, and wherein energy from at least a portion of a stream selected from W*3, W*4 is applied to the crude product RP C is transferred.

[0326] The process according to the preferred aspect of the invention is one for transalcoholization of a given alkali metal alcoholate McOR' to another alkali metal alcoholate McOR”, as described, for example, in DE 27 26 491 A1 or WO 2021 / 122702 A1.

[0327] R' and R" are two different Ci to Ce hydrocarbon radicals, preferably two different Ci to C4 hydrocarbon radicals.

[0328] More preferably, R' is methyl and R” is a C2 to C4 hydrocarbon radical.

[0329] Even more preferably, R' is methyl and R" is selected from ethyl, n-propyl, iso-propyl, sec-butyl, 2-methyl-2-butyl, tert-butyl, 2-methyl-2-pentyl, 3-methyl-3-pentyl, 3-ethyl-3-pentyl, 2-methyl-2-hexyl, 3-methyl-3-hexyl, in particular selected from ethyl, iso-propyl, 2-methyl-2-butyl, 3-methyl-3-pentyl, 3-ethyl-3-pentyl. Even more preferably, R' = methyl and R" = ethyl.

[0330] The process according to the preferred aspect of the invention (hereinafter also referred to as “transalcoholization”) is carried out in a reactive rectification column RR C Suitable reactive rectification columns are those described in section 4.1 in the context of step (a1) for RR A are described.

[0331] The reaction column RR C is operated with or without, preferably with a return flow. If a return flow is used, the vapor S C B partially or completely via a capacitor K RRC and the condensed vapor can then be fed back to the reaction column RRc or, if R' = methyl, as reactant stream SAEI or S B Ei can be used. If R' = methyl, it can also be used as fresh alcohol stream in RD A be used.

[0332] During the alcohol conversion process, at the lower end of RR C a bottom product stream S Cp comprising McOR”. At the upper end of RR C becomes a vapor stream S C B comprising R'OH.

[0333] In a preferred embodiment, when R' = methyl, the reactant stream S C EI comprising McOR' and optionally R'OH at least a part of S AP used and when step (a2) is carried out, alternatively (when MA and MB are different alkali metals or when MA and MB are the same alkali metal, in particular when MA and MB are different alkali metals) or additionally (in particular when MA and MB are the same alkali metal) at least a part of S B p is used. Particularly preferred is then R" = ethyl. Accordingly, a transalcoholization of alkali metal methoxide to the corresponding alkali metal ethoxide takes place.

[0334] If S BP and S APcomprise the same alkali metal methoxide, these two streams can also be used separately or mixed as S C EI are used, that is to say first mixed and then added to the column RR C as reactant stream S C EI or separately to the column RR C as two reactant streams S C EI.

[0335] The reactant stream S C E2 comprises R”OH. In a preferred embodiment, the mass fraction of R”OH in S C E2 at > 85 wt.%, more preferably at > 90 wt.%, where S C E2 otherwise in particular contains McOR” or another denaturant. The reactant stream S C The alcohol R”OH used in E2 can also be commercially available alcohol with an alcohol mass fraction of more than 99.8 wt% and a water mass fraction of up to 0.2 wt%.

[0336] “Conversion of a reactant stream S CEI comprising McOR' and optionally R'OH with a reactant stream S C E2 comprising R”OH in countercurrent” is ensured according to the invention in particular by the feed point of at least part of the reactant stream S C EI comprising McOR' at the reaction column RR C above the feed point of the reactant stream S C E2 comprising R”OH.

[0337] The reaction column RR C is operated with or without, preferably with return.

[0338] The reaction column RR C In a preferred embodiment, comprises at least one evaporator, which in particular consists of intermediate evaporators Vzc and bottom evaporators V S c is selected. The reaction column RR C particularly preferably comprises at least one bottom evaporator V S c.

[0339] In the case of the reaction column RR C During the intermediate evaporation at least one side stream Szc from RR Cremoved (“withdrawn”) and fed to at least one intermediate evaporator Vzc.

[0340] In the case of the reaction column RR C During bottom evaporation, at least one stream, for example S C p from RR C taken (“subtracted”) and at least one part, in the case of S C p preferably a part to which at least one bottom evaporator V S c supplied.

[0341] Suitable evaporators that can be used as intermediate evaporators and bottom evaporators are described in section 4.1.

[0342] In the transalcoholization, energy, preferably heat, from at least a part of a stream selected from W*3, W*4 is transferred to the crude product RP C This is preferably done by transferring energy from at least a portion of a current selected from W*3, W*4 to S C EI or S C E2 before entering RR C are transmitted, and then from SC EI or S C E2 on the in RR C raw product RP C with which they mix.

[0343] Accordingly, energy, preferably heat, is extracted from at least a part of a heat carrier selected from W*3, W*4, in particular from at least one heat carrier selected from W* 3i , W* 32 , W*4, preferably from at least one heat carrier selected from W* 32 , W*4on the raw product RP C transmitted.

[0344] “Transfer of energy, preferably heat, from at least a part of W*3 to the raw product RP C “ also includes the transfer of energy, preferably heat, from at least one heat carrier selected from W*3i, W* 32 , W*3before its separation into W*3i, W* 32 , on the raw product RP C .

[0345] In addition, raw product RP C via an intermediate evaporator Vzc or a

[0346] sump evaporator Vsc and into Vzc or V S c Energy, preferably heat, from at least a part of a heat carrier selected from W*3, W*4 to the raw product RP C be transferred.

[0347] In addition, the bottom product stream S C p partly via a sump evaporator V S c and then partly back into RR C be returned, whereby in V S c Energy, preferably heat, from at least a part of a heat carrier selected from W*3, W*4 to the recycled part of S C p is transferred and then, in the column RR C , by S C p on crude product RP in the column C The transfer of energy from at least a portion of a heat transfer medium selected from W*3, W*4 to the aforementioned streams occurs directly or indirectly, i.e., with or without heat transfer medium W*i, as described in Section 4.7.

[0348] The preferred embodiment of the method according to the invention makes it possible to extract the energy from W*3, W*4, in particular from W*4, W*3i, W* 32 efficiently. This reduces the

[0349] Total energy demand.

[0350] 5. Examples

[0351] 5.1 Example 1 (not according to the invention), corresponds to Figure 1

[0352] The example not according to the invention corresponds to Figure 1 , except that the intercooler WT shown in Figure 1 (or Figure 2 or Figure 3) X <402> is not used. This also applies to non-inventive example 2 and inventive example 3.

[0353] A stream of aqueous NaOH (50 wt%) SAE2 <102> of 5000 kg / h is heated to 30 °C at the top of a reaction column RR A <100> In countercurrent, a vaporous methanol stream SAEI <103> of 56700 kg / h at the bottom of the reaction column RR A<100> The reaction column RR A <100> is operated at a head pressure of 1 .25 bar abs. At the bottom of the column RR A <100> a nearly water-free product stream S A p- <104> of 1,1000 kg / h (30 wt.% sodium methoxide in methanol). At evaporator V SA <105> the reaction column RR A <100> Approximately 1200 kW of heating power is fed in using low-pressure steam. A vaporous methanol-water stream SAB <107> is at the top of the reaction column RR A <100> of which 4000 kg / h are taken in the condenser K RRA <108> condensed and returned to the reaction column RR A <100> reduced, the remaining flow of 50800 kg / h is fed to a rectification column RD A <300> supplied.

[0354] The rectification column RD A <300> is operated at a head pressure of 1.1 bar abs. At the bottom of the rectification column RD A<300> a liquid water stream SUA <304> of 3500 kg / h (500 ppm wt. methanol). The bottom temperature of the RD A <300> is 105 °C at 1 .2 bar abs. At the top of the rectification column RD A <300> a vaporous methanol stream S OA <302> (1.1 bar, 67 °C; 200 ppm by weight water) of 100,000 kg / h, of which 43,300 kg / h are used as return and are discharged via a condenser K RD <407> in which the majority of the condensation heat (9.4 MW) is used to convert the working medium W*i <701 > n-butane at 61.8 °C and 6.7 bar abs. to the stream W*2 <702> to evaporate. The remaining vapor stream of the RD A <300> of 56700 kg / h is supplied to a compressor VD A B2 <303> , compressed to 1 .7 bar abs. and fed to the reaction column RR A <100> returned.

[0355] The gaseous n-butane stream W*2 <702> is fed to a compressor VDi <401 >, and preferably heated beforehand by a superheater (AT = 20 K). The resulting current W*3 <703> the compressor VD X <405> so that a multi-stage compression of the stream W*2 <702> to the current W*4 <704> A total of 169 t / h of W*2 <702> to the current W*4 <704> (18.6 bar abs.). This corresponds to a condensation temperature of 110.5 °C. In the heat exchanger V SR D <406> a temperature difference of 5 K is set and the heat of W*4 <704> on a part of SUAI <320> of the vapor stream SUA <304> transferred, so that a current W*i <701 > is again generated, which is again transferred to the capacitor K RD <407> Before the current W*i <701 > is fed back to the capacitor K RD<407> is supplied, any residual heat present in the condensed stream W*i <701 > can be used to superheat the n-butane stream upstream of the compressor VDi <401 >.

[0356] A total electrical compressor power of 2.7 MW is required, while no external heating media (e.g. steam) were needed.

[0357] 5.2 Example 2 (not according to the invention), corresponds to Figure 2:

[0358] The arrangement in non-inventive Example 2 corresponds to that according to Example 1 with the following differences:

[0359] The rectification column RD A <300> has an intermediate evaporator V ZRD <409> The rectification column RD A <300> a liquid flow SZÄ <305> at 80 °C and then in the intermediate evaporator V ZRD <409> around 10500 kW of heat are transferred, whereby the electricity is partially evaporated and then returned to the rectification column RDA <300> is supplied.

[0360] At the top of the rectification column RD A <300> a vaporous methanol stream S OA <302> (1.1 bar, 67 °C; 200 ppm water by weight) of 100,000 kg / h, of which 43,300 kg / h are used as return and are discharged via a condenser K RD <407> in which the majority of the condensation heat (9.5 MW) is used to convert the working medium W*i <701 > n-butane at 61.8 °C and 6.7 bar abs. to the stream W*2 <702> The remaining vapor flow of 56700 kg / h is fed to a compressor VD AB 2 <303> and compressed there to 1 .7 bar abs. and fed to the reaction column RR A <100> returned.

[0361] The gaseous n-butane stream \N*2 <702> is fed to a compressor VDi <401 > and preferably heated beforehand by a superheater (AT = 13 K). The current W*3 <703> A total of 127 t / h of W*2 <702> to the current W*3 <703> (11.5 bar abs.) compressed.

[0362] Compared to Example 1, the pressure level of the working fluid n-butane does not need to be selected as high, since the temperature in the intermediate evaporator V ZRD <409> 80 °C (and not 105 °C as in the sump of the RD A <300> ). Consequently, the electrical power of the compressor VDi <401 > is reduced compared to Example 1. Due to the lower temperature lift, the compressor power is 1 MW. A thermal power for the V ZRD <409> of 10.5 MW. Nevertheless, the use of a heat pump in the form described cannot achieve complete electrification of the RD A<300> The bottom evaporator <406> is operated with low-pressure steam (alternatively: another waste heat source), whereby 2.04 MW must be used.

[0363] A total of 1.0 MW of electrical power and 2.04 MW of heating steam are used. 5.3 Example 3 (according to the invention) corresponds to Figure 3:

[0364] The arrangement in Example 3 according to the invention corresponds to that according to Examples 1 and 2 with the following differences:

[0365] At the top of the rectification column RD A <300> a vaporous methanol stream S OA <302> (1.1 bar, 67 °C; 200 ppm water by weight) of 100,000 kg / h, of which 43,300 kg / h are used as return and are discharged via a condenser K RD <407> led.

[0366] 11.14 MW of condensation heat are generated in the condenser K RD<407> used to convert the working medium W*i <701 > n-butane at 61.8 °C and 6.7 bar abs. to the stream W*2 <702> to evaporate. The remaining vapor stream of the RD A <300> of 56700 kg / h is supplied to a compressor VD AB 2 <303> and compressed there to 1 .7 bar abs. and fed to the reaction column RR A <100> returned.

[0367] The gaseous n-butane stream \N*2 <702> is fed to a compressor VDi <401 >, and preferably heated beforehand by a superheater (AT = 20 K). The resulting current W*3 <703> (11.5 bar, 110.5 °C).

[0368] 127 t / h n-butane of stream W*3 <703> , (= current W* 3i <7031 >) are fed to the side evaporator V at 11 .5 bar abs. ZR D <409> to transmit 10.5 MW here.

[0369] The remaining part of the current W*3 <703> , so W* 32 <7032> , 29 t / h, is fed to the compressor VD X<405> supplied, and from 11.5 bar abs. to 18.6 bar abs. to the stream W*4 <704> compressed. Power W* 4 <704> is then at the sump evaporator V SR D <406> condensed (2.04 MW).

[0370] A total of 1 .4 MW of electrical power is required for the compressor stages VDi <401 > and VD2 <405> necessary.

[0371] Compared to Examples 1 and 2, the total energy requirement is reduced under the same boundary conditions and at the same power output. Furthermore, compared to Example 2, no additional heating medium is used. This column is therefore completely converted to electricity. Using green electricity, CO2-free separation can be guaranteed.

[0372] The total energy required is minimized by the process according to Example 3.

[0373] The required proportion of heating power from low-pressure steam and compressor power is shown in Figure 10.

[0374] Result: The inventive procedure of compressing the heat medium step by step and thus operating the intermediate evaporator and bottom evaporator with the differently compressed heat medium can surprisingly save energy.

Claims

Patent claims 1 . A process for preparing at least one alkali metal methoxide of the formula MAOCH3, wherein MA is selected from sodium, potassium, lithium, wherein: (a1) a reactant stream SAEI comprising methanol with a reactant stream SAE2 comprising MAOH in countercurrent in a reactive rectification column RR A to a raw product RP A comprising MAOCHS, water, methanol, MAOH, whereby at the lower end of RR A a bottom product stream S A p comprising methanol and MAOCH3 and is taken at the upper end of RR A a vapor stream SAB comprising water and methanol is taken, (a2) and optionally, simultaneously with and spatially separated from step (a1), a reactant stream SBEI comprising methanol with a reactant stream S B E2 comprising MBOH in countercurrent in a reactive rectification column RR B to a raw product RP Bcomprising MBOCH3, water, methanol, MBOH, wherein MB is selected from sodium, potassium, lithium, wherein at the lower end of RR B a bottom product stream S BP comprising methanol and MBOCH3 and is taken at the upper end of RR B a vapor stream S BB comprising water and methanol, (a3) at least a portion of the vapor stream SAB, and, if step (a2) is carried out, at least a portion of the vapor stream S BB , mixed with SAB or separated from SAB, into a rectification column RD A is managed and in RD A into at least one vapor stream S OA comprising methanol, which is at the upper end of RD A and at least one stream SUA comprising water, which is taken at the lower end of RD A is taken, separated, (b) at least one side stream SZA from RD A is removed and returned to RD A is returned, (c) Energy of at least a part of S OA is transferred to a liquid or gaseous heat carrier W*i, whereby a gaseous heat carrier W*2 is obtained, (d) at least a portion of the gaseous heat carrier W*2 is compressed, thereby obtaining a gaseous heat carrier W*3 that is more compressed than W*2, (e) Energy of a first part W* 3i of the gaseous heat carrier W*3 is transferred to SZA before SZA in RD A is returned, (f) one of W* 3i different part of the gaseous heat carrier W*3, W* 32 , is further compressed, resulting in a 3i compressed gaseous heat carrier W*4 is obtained, (g) Energy of at least a part of W*4 is transferred to at least a part SUAI of SUA before SUAI is transferred to RD A is returned.

2. The method according to claim 1, wherein in step (e) energy of W* 3iis transferred to SZA in an intermediate evaporator VZRD.

3. A process according to claim 1 or 2, wherein in step (g) energy of at least a portion of W*4 is applied to the at least a portion SUAI of SUA in a bottom evaporator V S RD is transferred.

4. A method according to any one of claims 1 to 3, wherein energy from at least a part of W*3i, after energy from W* 3i transferred to SZA in accordance with step (e), to S OA is transferred, and / or energy from at least a part of W*4, after energy has been transferred from it to the at least a part SUAI of SUA according to step (g), to S OA is transferred.

5. Process according to one of claims 1 to 4, wherein at least two of the columns are selected from rectification column RD A , reaction column RR A and, if step (a2) is carried out, reaction column RR Bare housed in a column shell, the columns being at least partially separated from one another by a partition wall extending to the bottom of the column.

6. The method according to any one of claims 1 to 5, wherein a part of S OA in step (a1) as reactant stream SAEI and, if step (a2) is carried out, alternatively or additionally in step (a2) as reactant stream SBEI.

7. A process according to any one of claims 1 to 6, wherein energy from at least a portion of a stream selected from W*3, W*4 is applied to the crude product RP A and, if step (a2) is carried out, alternatively or additionally to the crude product RP B is transferred.

8. The process according to any one of claims 1 to 7, wherein MA is selected from sodium, potassium and, when step (a2) is carried out, MB is selected from sodium, potassium.

9. The process of claim 8, wherein MA is selected from sodium and, when step (a2) is performed, MB is selected from potassium.

10. Process according to one of claims 1 to 9, wherein in a reactive rectification column RR C a reactant stream S C EI comprehensive M C OR' with a reactant stream S C E2 comprising R”OH in countercurrent to a crude product RP C comprising McOR” and R'OH, whereby at the lower end of RR C a bottom product stream S C p comprising McOR” and at the upper end of RR C a vapor stream S C B comprising R'OH, and wherein R' and R" are two different Ci to Ce hydrocarbon radicals, and Mc is a metal selected from lithium, sodium, potassium, and wherein energy from at least a portion of a stream selected from W*3, W*4 is applied to the crude product RP C is transferred.

11. The process according to claim 10, wherein R' = methyl.

12. The method according to claim 11, wherein S AP obtained by the process according to claims 1 to 9, and wherein at least part of S AP as S C EI is used.

13. The method according to claim 11, wherein S B p is obtained by the process according to claims 1 to 9 by carrying out step (a2), and wherein at least a part of S B p as S C EI is used.

14. A process according to any one of claims 11 to 13, wherein R" is selected from ethyl, n-propyl, iso-propyl, sec-butyl, 2-methyl-2-butyl, n-butyl, 2-methyl-2-pentyl, 3-methyl-3-pentyl, 3-ethyl-3-pentyl, 2-methyl-2-hexyl, 3-methyl-3-hexyl.

15. The process of claim 14, wherein R" = ethyl.

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