Integrated process for simultaneously preparing alkali metal methoxides

Abstract

In a first aspect, the present invention relates to an integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide and methanol, comprising preparing one or more alkali metal methoxides in n reactive distillation columns K(i) under reactive distillation conditions from n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) comprising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; wherein at least a first stream W(1) and a second stream W(2) are at least partially fed into the rectification column D in that at least a part of the stream W(1) is fed into the lower part of the rectification column D at a position 1(1); and at least a part of the stream W(2) is fed into the lower part of the rectification column D at a position I(2), wherein the position l(2) is located below the position 1(1) and wherein between the positions 1(1) and l(2), the rectification column D is equipped with internals. A second aspect of the invention relates to a chemical production unit for carrying out the process according to the first aspect; and a third aspect of the invention is directed to the use of a chemical production unit according to the second aspect or of a process according to the first aspect for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol.

Description

[0001]Integrated process for simultaneously preparing alkali metal methoxides In a first aspect, the present invention relates to an integrated process for simultaneously pre- paring n mixtures P(i) comprising alkali metal methoxide and methanol, with a rectification col- umn D comprising at least one reboiler V(1a); the process comprising preparing one or more al- kali metal methoxides in n reactive distillation columns K(i) under reactive distillation conditions from n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streamsW(i) comprising methanol and water; and obtaining n bottoms streams P(i) comprising alkalimetal methoxide A(i)OMe and methanol; wherein at least a first stream W(1) and a second stream W(2) are at least partially fed into the rectification column D in that at least a part of the stream W(1) is fed into the lower part of the rectification column D at a position I(1); and at least a part of the stream W(2) is fed into the lower part of the rectification column D at a position I(2), wherein the position I(2) is located below the position I(1) and wherein between the positions I(1) and I(2), the rectification column D is equipped with internals. A second aspect of the inven- tion relates to a chemical production unit for carrying out the process according to the first as-pect; and a third aspect of the invention is directed to the use of a chemical production unit ac-cording to the second aspect or of a process according to the first aspect for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol. State of the art In the prior art, processes are described wherein a mixture comprising an alkali metal alkoxide and methanol is prepared in a reactive distillation column from a methanol stream and an aque- ous stream which comprises a dissolved alkali metal hydroxide. According to these processes, the methanol stream fed into the reactive distillation column is prepared by separating methanol from water in a distillation column upstream of the reactive distillation column and using the re-spectively obtained methanol to the reactive distillation column. In this respect, reference ismade, for example, to US 2002 / 0183566 A1, US 2008 / 0296786 A1, or WO 2013 / 168113 A1. However, according to the teaching of these prior art documents, only one specific mixture com- prising alkali metal methoxide and methanol could be produced. WO 2021 / 148174 A1 refers to a process for simultaneously preparing two mixtures comprising sodium metal alkoxide and potassium metal alkoxide as well as methanol, wherein a single rec-tification column is employed for generating a methanol stream which is then used as a metha-nol source for two parallel downstream reactive distillation columns in which the two different mixtures comprising alkali metal alkoxide and methanol are simultaneously prepared. Methanolcontaining streams from the two reactive distillation columns in vapor form are then combinedand fed into the rectification column. WO 2022 / 263032 A1 also discloses a process for simultaneously preparing two mixtures com- prising alkali metal alkoxide and methanol in separate reactive distillation columns with one rec-tification column for methanol. Vaporous methanol containing streams from the two reactive dis-tillation columns are combined and introduced into the rectification column. WO 2022 / 117803 A1 discloses a process for simultaneously preparing two or more mixturescomprising alkali metal hydroxide and methanol, wherein a single rectification column D is em-ployed for generating a methanol stream which is then used, after a suitable dividing into two or more substreams, as a methanol source for two or more parallel downstream reactive distillation columns in which two or more different mixtures comprising alkali metal methoxide and metha- nol are simultaneously prepared. Therein, a part stream of a vapor phase comprising methanol and taken at the top of the rectification column D, is compressed and used as heating mediumfor an intermediate reboiler of the rectification column D, thus covering the energy demand ofsaid intermediate reboiler. Top streams from the reactive distillation columns containing metha-nol are combined and re-introduced into the single rectification column D for methanol recovery.However, there is still a need for improvement, both in terms of energy demand and in terms ofapparatus costs, but also in terms of product purity. For example, re-introduction of the metha-nol containing streams from the reactive distillation columns into the single distillation column D bears the problem of bringing water into said column D, this in turn having a negative impact on the purity and water content of the products intended to be obtained from the reactive distillation columns.Therefore, it was an object of the present invention to provide an economically advantageousprocess for simultaneously preparing two or more mixtures comprising alkali metal hydroxide and methanol. It was a further object of the present invention to provide a process for preparingtwo or more mixtures comprising alkali metal hydroxide and methanol, which allows an im-proved purity of the desired products. Surprisingly, it was found that these objects can be solved by a process according to which asingle rectification column is used, wherein at least a first top stream W(1) comprising methanoland water and a second top stream W(2) comprising methanol and water from the reactive dis-tillation columns are at least partially fed into the single rectification column D in that at least apart of the stream W(1) is fed into the lower part of the rectification column D at a position I(1); and at least a part of the stream W(2) is fed into the lower part of the rectification column D at a position I(2), wherein the position I(2) is located below the position I(1) and wherein between the positions I(1) and I(2), the rectification column D is equipped with internals. It was found that this arrangement results in a significantly smaller water concentration at the top of the rectificationcolumn D and also in in a better product quality of the bottoms streams P(i) comprising alkalimetal methoxide A(i)OMe and methanol obtained from the reactive distillation columns, espe-cially the methanolic sodium methylate solution, especially a decreased water content of said methanolic sodium methylate solution.Thus, the invention relates in a first aspect to an integrated process for simultaneously prepar-ing n mixtures P(i) comprising alkali metal methoxide and methanol, comprising providing n reactive distillation columns K(i); providing n aqueous liquid streams H(i), a given stream H(i) comprising a dissolved alkali metal hydroxide A(i)OH, wherein n is an integer with n ≥ 2 and i = 1…n; and providing a rectification column D comprising at least one reboiler V(1a); wherein the process comprises preparing the one or more alkali metal methoxides in the n reac- tive distillation column K(i) under reactive distillation conditions from the n streams H(i) and nstreams G(i) comprising methanol, thereby obtaining n top streams W(i) comprising methanoland water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising(a) obtaining a vapor phase V comprising methanol at the top of the rectification column D,said vapor phase V having a pressure pVand a temperature TV; (b) preparing at least two streams from the vapor phase V, comprising a vapor stream G hav- ing a pressure pG and a temperature TG with 0.95 ≤ pG / pV ≤ 1.00, and further comprising a stream T(1a), said stream T(1a) having a pressure pT(1a) and a temperature TT(1a) with pT(1a) > pV and TT(1a) > TV;(c) preparing the n streams G(i) from the vapor stream G, each of the streams G(i) having apressure pG(i) and a temperature TG(i) with pG(i) > pG for each stream G(i); and feeding each stream G(i) into the respective reactive distillation column K(i);(d) passing at least a part of the stream T(1a) as a heating medium through the reboiler V(1a)of the rectification column D, obtaining a, preferably at least partially condensed, stream TC(1a) having a temperature TTc(1a) with TTc(1a) < TT(1a);(e) feeding at least a part of the stream TC(1a) into the rectification column D;(f) feeding at least a first stream W(1) and a second stream W(2) at least partially into therectification column D, comprising (f.1) feeding at least a part of the stream W(1) into the lower part of the rectification col-umn D at a position I(1);(f.2) feeding at least a part of the stream W(2) into the lower part of the rectification col-umn D at a position I(2), wherein the position I(2) is located below the position I(1); wherein between the positions I(1) and I(2), the rectification column D is equipped with in- ternals.Feeding of at least a part of the stream TC(1a) into the rectification column D according to (e) ispreferably done as explained in more detail herein below.In some preferred embodiments of the process, the rectification column D is equipped below theposition I(2) with internals. In some preferred embodiments of the process, the rectification column D’s internals are se- lected from tray, unstructured (random) packing, structured packing and mixtures of two or more thereof. Preferably, rectification column D comprises one or more internals, preferably selected from the group consisting of tray, unstructured (random) packing, structured packing and mix- tures of two or more thereof. A tray is preferably selected from the group consisting of bubbletray, sieve tray, valve tray, tunnel tray, slot tray and mixtures of two or more thereof. An unstruc-tured packing is preferably selected from the group consisting of Raschig rings, Pall rings, Berlsaddles, lntalox saddles and mixtures of two or more thereof. Structured packings are sold, forexample, under the trade name Mellapack® from Sulzer. In addition to the internals mentioned, other suitable internals are known to those skilled in the art and can also be used. If structured packings or unstructured packings are contained in the rectification column, these can be di-vided or there can be one continuous packing.In some preferred embodiments of the process, the rectification column D has in the range offrom 20 to 100, more preferably in the range of from 30 to 80, more preferably in the range offrom 40 to 60 theoretical trays. In some preferred embodiments of the process, position I(2) islocated in the lower half of rectification column D, preferably in the lower third of rectification col- umn D, wherein more preferably I(2) is located between the 4thand the 20ththeoretical stage, more preferably between the 5thand the 15ththeoretical stage, more preferably between the 5thand the 12th theoretical stage of the rectification column D, counted from the bottom. In somepreferred embodiments of the process, position I(1) is located in the lower half of rectificationcolumn D, preferably in the lower third of rectification column D, wherein more preferably in the range of from 1 to 15 preferably of from 2 to 10, more preferably of from 3 to 5, theoretical trays are present between the position I(2) and I(1). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the MeOH con- centration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2), so that W(1) is fed into rectification column D at a position I(1), wherein the MeOH concentration at that position I(1) within the rectification column D cMeOH(D1) is preferably about equal to cMeOH(1) with 0.95 ≤ cMeOH(1) / cMeOH(D1) ≤ 1.05. W(2) is preferably fed into rectification column D at a position I(2), wherein the MeOH concen- tration at that position I(2) within the rectification column D cMeOH(D2) is preferably about equal to cMeOH(2) with 0.95 ≤ cMeOH(2) / cMeOH(D2) ≤ 1.05. This preferred feeding manner enables a most efficient processing of rectification column D.In some preferred embodiments, the process comprises for n reactive distillation columns K(i),feeding the stream G(i) into the lower part of the reactive distillation column K(i) and feeding the aqueous liquid stream H(i) into the upper part of the reactive distillation column K(i).In some preferred embodiments of the process, prior to preparing the n streams G(i) from thevapor stream G according to (c), the stream G is passed through a compressor CG, thereby ob- taining a compressed stream Gchaving a pressure pGc> pG. In some preferred embodiments of the process, prior to be fed into the reactive distillation column K(i), each of the n streams G(i) is passed through a compressor C(i), thereby obtaining n compressed streams Gc(i) having a pressure pGc(i)with pGc(i)> pG.In some preferred embodiments of the process, n is 2 (n = 2). Preferably, the stream H(1) com-prises dissolved sodium hydroxide and the stream H(2) comprises dissolved potassium hydrox- ide, wherein sodium methoxide is prepared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is prepared in the reactive distillation col- umn K(2) from which the stream W(2) is obtained.In some preferred embodiments of the process, the stream W(1) comprises methanol and waterat a molar methanol-to-water ratio r(1) and wherein the stream W(2) comprises methanol andwater at a molar methanol-to-water ratio r(2) with r(2) < r(1). In other words, the water content ofstream W(1) is lower than the water content of the stream W(2).In some preferred embodiments, the process comprises feeding a stream M comprising metha-nol into the rectification column D at a position I(M). In these preferred embodiments of the pro-cess, the positions I(1) and I(2) are preferably located below the position I(M). I(M) is preferablyin the upper half of rectification column D, more preferably in the upper third of rectification col- umn D; and I(1) and I(2) are located in the lower half of rectification column D.As indicated above, a stream M comprising methanol is fed into the rectification column D. Thisstream M, also referred to as fresh methanol stream M, is fed into D in order provide sufficient methanol for the overall process, in particular to compensate the loss of methanol removed from the process via the mixtures P(i). Generally, there are no specific requirements as far as the methanol content of M is concerned, and the skilled person will be in the position to choose suit- able methanol streams M. Preferably, however, it is preferred that the stream M comprises only a low amount of water. Therefore, it is further preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream M consist of methanol and optionally water, wherein the amount of water comprised in the stream M is preferably at most 2000 weight-ppm, more preferably at most 1500 weight-ppm, more pref- erably at most 1000 weight-ppm, such as at most 750 weight-ppm or at most 500 weight-ppm or at most 250 weight-ppm. Generally, the stream M can be fed into the rectification column D at any suitable position. How- ever, as indicated above, I(M) is preferably in the upper half of rectification column D, more pref- erably in the upper third of rectification column D, more preferably at least 2, 3 or 4 theoretical stages from the top of D, more preferably at least 4 theoretical stages from the top of D, more preferably between the 4thand the 20ththeoretical stage from the top of D, more preferably be- tween the 6thand the 15ththeoretical stage from the top of D, such as between the 6thand the 10ththeoretical stage or between to 8thand the 12ththeoretical stage or between the 10thand the 14ththeoretical stage or between to 12thand the 15ththeoretical stage. Preferably, M with its methanol concentration cMeOH(M) is fed into rectification column D at a po- sition I(M), wherein the MeOH concentration at that position I(M) within the rectification columnD cMeOH(DM) is preferably about equal to cMeOH(M) with 0.95 ≤ cMeOH(M) / cMeOH(DM) ≤ 1.05. Thispreferred feeding manner enables a most efficient processing of rectification column D. As far as the temperature of the stream M is concerned at which the stream M is fed into D, it is preferred that the temperature is in the range of from ambient temperature up to the boiling point of methanol at the column pressure of D; more preferably the temperature is ambient tem- perature.In some preferred embodiments of the process, the rectification column D is operated at a pres-sure at the top of D in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs). In some preferred embodiments of the process, the rectification columnD is operated at a temperature at the top of D in the range of from 45 to 137 °C, preferably inthe range of 49 to 118, more preferably in the range of from 64 to 111 °C, more preferably in therange of from 64 to 95°C. Rectification column D without top vapor recompression In some embodiments of the process, the rectification column D is operated without top vapor recompression. Rectification column D with top vapor recompressionIn some preferred embodiments of the process, the rectification column D is operated at a refluxratio of at least 0.5:1, preferably in the range of from 0.55:1 to 1.4:1, ore preferably in the rangeof from 0.6:1 to 1.4:1. Preferably, the rectification column is operated with top vapor recompres-sion. In some preferred embodiments of the process, realizing the reflux ratio comprises prepar-ing from the vapor phase V a further vapor stream T(2), passing said stream T(2) through a condenser V(2), obtaining a liquid stream T(3) and a waste gas stream T(2w), and feeding theliquid stream T(3) into the top of the rectification column D. Preferably, the waste gas streamT(2w) essentially consists of oxygen, nitrogen, carbon dioxide and methanol, wherein the amount of methanol in T(2w) is preferably in the range of from 2 to 80 weight-%, preferably in the range of from 10 to 30 weight-% based on the total weight of T(2w). Recirculation of Tc(1a) into DIn some preferred embodiments of the process, at least a part of Tc(1a) is fed to a condensatedrum CD(1), wherein from said condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) together with T(2)and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depres-surized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. In “depressurized form” regarding the liquid streams T(1l), T(2l) and (T2gl) and the combined stream respectively means that these streams and respectively the combined liquid stream therefrom have a pressure pcs about equal to the pressure at the top of rectification column D as described above, i.e.0.95 ≤ pcs / ptD ≤ 1.05. In particular in view of overall energy consumption topics, the rectification column D is operated with top vapor recompression. Reference is made, for example, to the schematic overview in Figure 1 showing a process according to the present invention with reflux. When the rectificationcolumn is operated with top vapor recompression, it is also preferred that realizing the reflux ra-tio comprises using 2 condensers, V(2) and V(3), as described below in that(i) in addition to the at least two streams G and T(1a), which are prepared from the vaporphase V, preparing a further stream T(2) from the vapor phase V and passing said stream T(2) through the condenser V(2), obtaining a liquid stream T(2l) and a gas stream T(2g); passing the gas stream T(2g) through the condenser V(3), obtaining a liquid stream T(2gl) and a waste gas stream T(2w); and combining the liquid streams T(2l) and (T2gl) in de- pressurized form in a second condensate drum CD(2);(ii) feeding Tc(1a), at least partially, to a first condensate drum CD(1), wherein from said firstcondensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) together with T(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form in the second condensate drum CD(2), obtaining a combined liquid stream which isfed as the stream T(3) into the top of the rectification column D. Certainly, as far as step (i) above is concerned, the skilled person may also realize, if need be,said reflux ratio by using more than the 2 condensers V(2) and V(3) or by using only one con-denser V(2). Vapor phase VIn some preferred embodiments of the process, the vapor phase V has a pressure pV, in therange of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more prefer- ably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs). In some preferred embodiments of the process, the vapor phase V has a temperature TV in therange of from45 to 137 °C, preferably in the range of 49 to 118, more preferably in the range offrom 64 to 111 °C, more preferably in the range of from 64 to 95°C .Stream taken from rectification column D for heating purpose regarding reboiler V(1a)In some preferred embodiments of the process, a stream T(Di) having a temperature TT(Di) and apressure pT(Di) is taken from the rectification column D and passed for heating purpose through the reboiler V(1a) of the rectification column D, obtaining a heated stream Th(Di) having a tem-perature TTh(Di) with TTh(Di) > TT(Di), wherein heated stream Th(Di) is reintroduced into rectificationcolumn D. Heated stream Th(Di) preferably comprises two phases, i.e. a gaseous and a liquidpart. In some preferred embodiments of the process, V(1a) is an intermediate reboiler of therectification column D and the stream T(Di) is preferably taken at an intermediate position from rectification column D. Stream T(1)In some preferred embodiments of the process, preparing the at least two streams according to(b) comprises(b.1) splitting the vapor phase V into at least two vapor streams comprising the stream G and avapor stream T(1) having a pressure pT(1) and a temperature TT(1) with 0.95 ≤ pT(1) / pV ≤ 1.00;(b.2) preparing at least stream T(1a) from the vapor stream T(1), wherein for preparing thestream T(1a) a first compression unit CT(1) is employed. Stream T(1a)In some preferred embodiments of the process, stream T(1a) has a pressure pT(1a), which is ad-justed so that TcondT(1a) is ≥ TboilT(Di) + 3 K, wherein TcondT(1a) is the condensation temperature ofstream T(1a) at a pressure pT(1a) and TboilT(Di) is the boiling temperature of stream T(Di) at a pres-sure pT(Di).In some preferred embodiments of the process, stream T(1a) has a condensationtemperature TcondT(1a) which is in the range of from 3 to 30 K, preferably in the range of from 4and 25 K, more preferably in the range of from 5 and 20 K, higher than TboilT(Di). Stream G, streams G(i) With respect to the stream G, it is preferred that said stream G comprises methanol and water, wherein more preferably from 99.95 to 100 weight-% of G consist of methanol and water, andwherein the water content of G is at most 200 weight-ppm, more preferably at most 150 weight-ppm, more preferably at most 100 weight-ppm, wherein more preferably, said water content is in the range of from 5 to 100 weight-ppm, more preferably in the range of from 10 to 100 weight- ppm, more preferably in the range of from 15 to 100 weight-ppm. According to (c), n streams G(i) are prepared from the vapor stream G, each of the streams G(i) having a pressure pG(i) anda temperature TG(i) with pG(i) > pG and TG(i) > TG for each stream G(i), and feeding each streamG(i) into the respective reactive distillation column K(i), wherein for preparing the n streams G(i), the at least one compression unit CG is employed.Preferably, the stream G is divided into the two streams G(1) and G(2), wherein the stream Ghas a mass flow rate f(G), the stream G(1) has a mass flow rate f(G(1)) and the stream G(2) has a mass flow rate f(G(2)), wherein f(G) = f(G(1)) + f(G(2)). Generally, the stream G can be di- vided by any conceivable method. Preferably (c) comprises passing the stream G into a stream dividing device S, said device more preferably comprising a pipe junction. In context, it is noted that the term “the stream is divided into two streams” refers to a method according to which the streams obtained from said dividing have the same chemical composition as the stream G. As far as the ratios f(G(1)) / f(G) and f(G(2)) / f(G) are concerned, the present invention allows for a flexible adjusting of said ratios in that the individual flow rates f(G(1)) and f(G(2)) can be chosen depending on the desired amount of A(1)OMe, preferably sodium methoxide, to be obtained rel- ative to the desired amount of A(2)OMe, preferably potassium methoxide, to be obtained. Prior to dividing according to (c), the stream G can be passed through the at least one compres- sion unit CG, thereby realizing a pressure increase of G. Preferably, the pressure is suitably in- creased so that the pressure of the streams after dividing is adapted to the desired pressure when the streams are fed into the reactive distillation columns K(i) and ultimately, via the streams W(i), back into D. Preferably, said pressure increase is in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. According to this embodiment of the present invention, it is preferred that the di- viding according to (c) comprises passing the compressed stream G into a stream dividing de- vice S, said device preferably comprising a pipe junction and at least one control device allow- ing for adjusting the ratio f(G(1)) / f(G(2)), wherein said at least one control device is located downstream of said pipe junction. At least one of these control devices is located either in the stream G(1) or in the stream G(2) or in both streams G(1) and G(2), and it is preferred that the at least one control device preferably is a control valve. Afterwards, the compressed stream G is fed into the dividing device S and consequently, the resulting streams G(1) and G(2) are fed into the reactive distillation columns K(1) and K(2) respectively. Alternatively, the pressure increase mentioned above is realized not by compressing the stream G prior to, but after dividing. In this alternative embodiment, stream G is fed to a dividing device S and divided in a stream G(1) and a stream G(2). Prior to be fed into the reactive distillation column K(1), the stream G(1) is passed through a compression unit CG(1), thereby realizing a pressure increase of G(1) in the range of from 0.1 to 0.8 bar, preferably in the range of from 0.15 to 0.6 bar, more preferably inthe range of from 0.2 to 0.4 bar. Certainly, said compression of G(1) can be combined with apre-compression of the stream G prior to dividing; however, it is preferred that this compressing of G(1) is performed with no compression of G being performed prior to dividing. Consequently,in this alternative embodiment, it is also preferred that prior to be fed into the reactive distillationcolumn K(2), the stream G(2) is passed through a compressor CG(2), thereby realizing a pres- sure increase of G(2) in the range of from 0.1 to 0.8 bar, preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. Certainly, said compression of G(2) can be combined with a pre-compression of the stream G prior to dividing; however, it is pre- ferred that this compressing of G(2) is performed with no compression of G being performed prior to dividing. As far as the stream H(1) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream H(1) consist of A(1)OH and water, wherein more preferably from 37.5 to 58 weight-%, more preferably from 40 to 55 weight-%, more preferably from 42.5 to 52 weight-% of the stream H(1) consist of A(1)OH, preferably sodium hydroxide. Preferably the stream H(1) is fed into the reac- tive distillation column K(1) at a temperature of H(1) in the range of from ambient temperature to its boiling temperature, more preferably in the range of from 50 to 80 °C such as from 50 to 60 °C or from 60 to 70 °C or from 70 to 80 °C. Heating of the stream H(1) to this temperature may be accomplished with any suitable means such as a heat exchanger. It is preferred that the stream H(1) is fed into the top of the reactive distillation column K(1), more preferably to the first theoretical stage from the top. As to the reactive distillation column K(1), it is preferred that said column has from 5 to 50, morepreferably from 10 to 40, more preferably from 15 to 30 theoretical stages, such as from 15 to20 or from 20 to 25 or from 25 to 30 theoretical stages. Generally, the stream G(1) can be fed at any suitable position into K(1); preferably, G(1) is fed into the reactive distillation column K(1) at a position between the bottoms and the 5ththeoretical stage, more preferably between the bot- toms and the 3rdtheoretical stage, more preferably between the bottoms and the 2ndtheoretical stage of the reactive distillation column K(1). Preferably, the reactive distillation column K(1) is operated at a pressure at the top in the range of from 0.5 to 10 bar(abs), more preferably in the range of from 1 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs). Suitable pre- ferred ranges are, for example, from 1 to 3 bar(abs) or from 2 to 4 bar(abs) of from 3 to 5 bar(abs). While it is generally possible to operate the reactive distillation column K(1) with reflux, it is preferred that the reactive distillation column K(1) is operated at a reflux ratio of 0:1. As far as the stream W(1) is concerned which is obtained from the top of K(1), it is preferred that from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of W(1) consist of methanol and water. More preferably, from 1 to 10 weight-%, more preferably from 2 to 8 weight-%, more preferably from 4 to 7 weight-%, more preferably from 5 to 6 weight-% of the stream W(1) consist of water.As far as the mixture P(1) is concerned, it is preferred that from 99 to 100 weight-%, more pref-erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream P(1) consist of A(1)OMe, preferably sodium methoxide, and methanol. More preferably, from 10 to 50 weight-%, more preferably from 20 to 40 weight-%, more preferably from 25 to 35 weight-% of the stream P(1) consist of A(1)OMe, preferably sodium methoxide. More preferably, at most 5000 weight-ppm, more preferably at most 2000 weight-ppm, more preferably at most 1000 weight-ppm of the stream P(1) consist of water. Conceivable maximum water contents may in- clude, for example, 750 weight-ppm or 500 weight-ppm or 250 weight-ppm. Preferably, the con- centration of A(1)OMe, preferably sodium methoxide in the stream P(1) are realized by the skilled person by operating the reactive distillation column K(1) at a respective reboiler duty. According to the present invention, it is preferred that the top of the reactive distillation columnK(1) is equipped with a suitable droplet separating device D(1), preferably a demister. Thus, theprocess preferably comprises separating droplets comprising A(1)OH, preferably sodium hy- droxide, from the vapor stream in the top of K(1). It is further preferred that, in particular for cleaning purposes, said demister is suitably treated with a suitable stream M(1). A preferred treating may comprise, preferably consist of at least temporarily spraying the demister with the stream M(1). Regarding the chemical composition of M(1), it is especially preferred that M(1) comprises methanol, wherein it is more preferred that M(1) is branched from a condensed top stream removed from the rectification column D, for example one of the streams described above, or being a fresh methanol stream, for example a stream branched from the stream M de- scribed above. As far as the stream H(2) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream H(2) consist of A(2)OH, preferably potassium hydroxide, and water, wherein more preferably 30 to 55 weight-%, more preferably from 40 to 52.5 weight-%, more preferably from 45 to 50 weight-% of the stream H(2) consist of A(2)OH, preferably potassium hydroxide. Preferably the stream H(2) is fed into the reactive distillation column K(2) at a temperature of H(2) in the range of from ambient temperature to its boiling temperature, more preferably in the range of from 50 to 80 °C such as from 50 to 60 °C or from 60 to 70 °C or from 70 to 80 °C. Heating of the stream H(2) to this temperature may be accomplished with any suitable means such as a heat ex- changer. It is preferred that the stream H(2) is fed into the top of the reactive distillation column K(2), more preferably to the first theoretical stage from the top. As to the reactive distillation column K(2), it is preferred that said column has from 5 to 50, more preferably from 10 to 40, more preferably from 15 to 30 theoretical stages, such as from 15 to 20 or from 20 to 25 or from 25 to 30 theoretical stages. Generally, the stream G(2) can be fed at any suitable position into K(2); preferably, G(2) is fed into the reactive distillation column K(2) at a position between the bottoms and the 5ththeoretical stage, more preferably between the bot- toms and the 3rdtheoretical stage, more preferably between the bottoms and the 2ndtheoretical stage of the reactive distillation column K(2). Preferably, the reactive distillation column K(2) is operated at a pressure at the top in the range of from 0.5 to 10 bar(abs), more preferably in the range of from 1 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs). Suitable pre- ferred ranges are, for example, from 1 to 3 bar(abs) or from 2 to 4 bar(abs) of from 3 to 5 bar(abs). While it is generally possible to operate the reactive distillation column K(2) with reflux, it is preferred that the reactive distillation column K(2) is operated at a reflux ratio of 0:1. As far as the stream W(2) is concerned which is obtained from the top of K(2), it is preferred that from 99 to 100 weight-%, more preferably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of W(2) consist of methanol and water. More preferably, from 1 to 15 weight-%, more preferably from 2 to 12 weight-%, more preferably from 6 to 10 weight-% of the stream W(2) consist of water. As far as the mixture P(2) is concerned, it is preferred that from 99 to 100 weight-%, more pref- erably from 99.5 to 100 weight-%, more preferably from 99.9 to 100 weight-% of the stream P(2) consist of A(2)OMe, preferably potassium methoxide, and methanol. More preferably, from 10 to 50 weight-%, more preferably from 20 to 40 weight-%, more preferably from 25 to 35 weight- % of the stream P(2) consist of A(2)OMe, preferably potassium methoxide. More preferably, at most 5000 weight-ppm, more preferably at most 2000 weight-ppm, more preferably at most 1000 weight-ppm of the stream P(2) consist of water. Conceivable maximum water contents may include, for example, 750 weight-ppm or 500 weight-ppm or 250 weight-ppm. Preferably, the concentration of A(2)OM, preferably potassium methoxide in the stream P(2) are realized by the skilled person by operating the reactive distillation column K(2) at a respective reboiler duty. According to the present invention, it is preferred that the top of the reactive distillation column K(2) is equipped with a suitable droplet separating device D(2), preferably a demister. Thus, the process preferably comprises separating droplets comprising A(2)OH, preferably potassium hy- droxide, from the vapor stream in the top of K(2). It is further preferred that, in particular for cleaning purposes, said demister is suitably treated with a suitable stream M(2). A preferred treating may comprise, preferably consist of at least temporarily spraying the demister with the stream M(2). Regarding the chemical composition of M(2), it is especially preferred that M(2) comprises methanol, wherein it is more preferred that M(2) is branched from a condensed top stream removed from the rectification column D, for example one of the streams described above, or being a fresh methanol stream, for example a stream branched from the stream M de- scribed above. In the above, it was described that according to the present invention, the stream G, prior to di- viding, is preferably passed through a compression unit CG. According to the present invention, it is also possible that either in addition to at least one of the above alternatives or, preferably as the sole respective compression, prior to being fed into the rectification column D, the stream W(1) is passed through a compression unit CG(1), thereby realizing a pressure increase of W(1) preferably in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar, and prior to being fed into the rectifica- tion column D, the stream W(2) is passed through a compression unit CG(2), thereby realizing a pressure increase of W(2) in the range of from 0.1 to 0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range of from 0.2 to 0.4 bar. According to this em- bodiment of the present invention, it is also possible to suitably combine the streams W(1) and W(2), prior to being passed through a compressor, in a combining device to obtain a respective combined stream W, and pass said combined stream W, prior to being fed into D, through a compressor, thereby realizing a pressure increase of W(1) preferably in the range of from 0.1 to0.8 bar, more preferably in the range of from 0.15 to 0.6 bar, more preferably in the range offrom 0.2 to 0.4 bar. Said combining device preferably comprises a pipe junction and at least one control device, preferably a control valve. As far as the integrated process of the present invention is concerned, it is noted that for simul- taneously preparing, in addition to the 2 mixtures P(1) and P(2) as described above in detail, a3rd mixture P(3) etc. can be obtained, the skilled person, based on his general knowledge, willbe in the position to derive from said details above in a straight-forward manner also any detail adjusting the overall process. According to the present invention, it is also conceivable that from at least one of the streams P(i), A(i)OMe is at least partially separated from methanol, more preferably obtaining solid, more preferably crystalline A(i)OMe. Thus, solid, preferably crystallinesodium methoxide and solid, preferably crystalline potassium methoxide, can be obtained.Parallel compression of T(1a), T(1b)In some preferred embodiments of the process, the rectification column D comprises at leastone reboiler V(1a) and at least one reboiler V(1b) and wherein the at least one reboiler V(1a) is an intermediate reboiler and the at least one reboiler V(1b) is a bottom reboiler; wherein (b) comprises preparing at least three streams from the vapor phase V, comprising the vapor stream G having a pressure pG and a temperature TG with 0.95 ≤ pG / pV ≤ 1.00, and further comprising two streams T(1a) and T(1b), said stream T(1a) having a pressure pT(1a) and a tem- perature TT(1a) with pT(1a) > pV and TT(1a) > TV and said stream T(1b) having a pressure pT(1b) and a temperature TT(1b) with with pT(1b) > pV and TT(1b) > TV; wherein (d) comprises(d.1) passing at least a part of the stream T(1a) as a heating medium through a reboiler V(1a),preferably an intermediate reboiler V(1a), of the rectification column D, obtaining a streamTC(1a) having a temperature TTc(1a) with TTc(1a) < TT(1a);(d.2) passing at least a part of the stream T(1b) as a heating medium through a reboiler V(1b),preferably a bottom reboiler V(1b), of the distillation column D, obtaining a stream TC(1b)having a temperature TTc(1b) with TTc(1b) < TT(1b); and wherein (e) comprises(e.1) feeding at least a part of the stream TC(1a) into the rectification column D;(e.2) feeding at least a part of the stream TC(1b) into the rectification column D. Feeding of at least a part of the stream TC(1a) into the rectification column D according to (e.1)is preferably done as explained in more detail herein, and also feeding at least a part of thestream TC(1b) into the rectification column D according to (e.2) is preferably done as explained in more detail herein. In some preferred embodiments of the process, preparing the at least three streams according to (b) comprises(b.1) splitting the vapor phase V into at least two vapor streams comprising the stream G and avapor stream T(1) having a pressure pT(1)and a temperature TT(1)with 0.95 ≤ pT(1) / pV≤ 1.00;(b.2) preparing at least the two streams T(1a) and T(1b) from the vapor stream T(1).Streams taken from rectification column D for heating purpose regarding intermediate reboiler(V1a) and bottom reboiler V(1b)In some preferred embodiments of the process, a stream T(Di) is taken from the rectificationcolumn D at an intermediate position and passed for heating purpose through an intermediate reboiler V(1a) of the rectification column D, obtaining a heated stream Th(Di) having a tempera-ture TTh(Di) with TTh(Di) > TT(Di), wherein heated stream Th(Di) is reintroduced into rectification col-umn D; and a stream T(Db) is taken from the rectification column D at a bottom position and passed forheating purpose through the bottom reboiler V(1b) of the rectification column D, obtaining astream Th(Db) having a temperature TTh(Db) with TTh(Db) > TT(Db), wherein heated stream Th(Db) isreintroduced into rectification column D. As described above, heated stream Th(Di) preferably comprises two phases, i.e. a gaseous anda liquid part. Analogously, heated stream Th(Db) preferably comprises two phases, i.e. a gase-ous and a liquid part. Stream T(1b) In some preferred embodiments of the process, stream T(1b) has a pressure pT(1b) ,which is ad-justed so that TcondT(1b) is ≥ TboilT(Db) + 3 K, wherein TcondT(1b) is the condensation temperature ofstream T(1b) at a pressure pT(1b) and TboilT(Db) is the boiling temperature of stream T(Db) at apressure pT(Db). In some preferred embodiments of the process, T(1b) has a condensation tem-perature TcondT(1b) which is in the range of from 3 to 30 K, preferably in the range of from 4 and25 K, more preferably in the range of from 5 and 20 K, higher than TboilT(Db.2nd aspect - Chemical production unitA second aspect of the present invention is directed to a chemical production unit for carrying out the process according to the second aspect of the invention, comprising- a rectification column D comprising-- in its lower part, inlet means for feeding streams W(i) or one or more combinedstream thereof into D; -- in its upper part, outlet means for removing a vapor stream V or divided streamsthereof, comprising at least a gaseous stream G and at a stream T(1a), from the top of D; -- at least one reboiler V(1a);- optionally a stream dividing device So for dividing V or substreams of V into (further) substreams thereof;- a first compressor CT(1) for compressing T(1a) or a part thereof;- means for passing compressed sub streams of T(1) from CT(1) as heating mediumthrough reboiler V(1a);- a stream dividing device S for dividing the stream G into n streams G(i);- means for passing the stream G to said stream dividing device S;- n reactive distillation columns K(i), n≥2 and i=1…n; said reactive distillation columns K(i)being arranged in parallel, each reactive distillation column K(i) comprising -- in its upper part, preferably in its top, inlet means for feeding a stream H(i) into K(i);-- in its lower part, inlet means for feeding a stream G(i) into K(i);-- outlet means for removing a stream W(i) from the top of K(i);-- a bottom reboiler;-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms stream re-moved from K(i);- means for passing the streams G(i) to the reactive distillation columns K(i);- preferably spatially separated means for passing at least one of the streams W(i) and atleast another one of the streams W(i) at different positions to the rectification column D;- one or more compressors C(i) for compressing either the stream G and / or the streamsG(i) and / or the streams W(i). Spatially separated means for passing at least one of the streams W(i) and at least another oneof the streams W(i) at different positions to the rectification column D are preferably spatiallyseparated in that they are located at different heights of the rectification column D. In some preferred embodiments, the chemical production unit comprises means for feeding a stream W(1) into the lower part of the rectification column D at a position I(1) and further means for feeding a stream W(2) into the lower part of the rectification column D at a position I(2), wherein the position I(2) is located below the position I(1). Preferably, the rectification column D of the chemical production unit is equipped with internals between the positions I(1) and I(2). All details, embodiments and preferred embodiments described above in the section related to the first aspect of the invention also apply for the second aspect of the invention.In some preferred embodiments, the chemical product unit comprises an intermediate reboilerV(1a) and a bottom reboiler V(1b) and further a second compressor CT(2) for compressing T(1b)or a part thereof, and means for passing compressed sub streams of T(1) from CT(2) as heating medium through bottom reboiler V(1b).In some preferred embodiments, the chemical product unit comprises means for passing con-densed sub streams of T(1a) and optionally of T(1b) after passage through intermediate reboiler V(1a) and optionally through bottom reboiler V(1b) into D, the means preferably comprising- at least one condenser, preferably a condenser V(2) and optionally a further condenserV(3) arranged downstream of V(2), having inlet means for receiving condensed stream of T(1a) after passage through intermediate reboiler V(1a) and optionally condensed stream T(1b) after passage through bottom reboiler V(1b), and having outlet means for removing a condensed stream T(3) and for removing a waste gas stream;- inlet means for feeding the stream T(3) to the top of D.In some preferred embodiments, the chemical product unit comprises inlet means for feeding amethanol stream M into D. Preferably, the top of at least one, more preferably of each reactive distillation column K(i) is equipped with a droplet separating device D(i), more preferably a demister, said demister more preferably comprising an inlet means for feeding a stream M(i) comprising methanol into said demister. Preferably each of the reactive distillations columns K(i) comprises, independently from one another, from 5 to 50, more preferably from 10 to 40, more preferably from 15 to 30 theoretical stages. It is preferred that the means for passing the streams G(i) to the reactive dis- tillation columns K(i) are located, independently from one another, at a position between the bottoms and the fifth theoretical stage, more preferably between the bottoms and the third theo- retical stage, more preferably between the bottoms and the second theoretical stage of K(i). Preferably, the means for passing the streams H(i) into the reactive distillation columns K(i) are located at the top of K(i), preferably at the uppermost theoretical stage. Preferably at least one, more preferably each reactive distillation columns K(i) does not comprise means for being oper- ated at a reflux ratio of greater than 0:1. Preferably each reactive distillation column K(i) is equipped with trays. It is preferred that the chemical production unit of the present invention comprises at least one compression unit CGarranged upstream of K(i) for compressing the stream G before passage into the stream dividing device S. Alternatively, it is preferred that the unit of the present inven- tion comprises n compressors C(i) arranged downstream of K(i) and upstream of D for com- pressing the streams W(i). It is preferred that the unit of the present invention further comprises at least one condensate drum (second condensate drum CD(2)) for a liquid stream removed from V(2) and optionally from V(3) and further comprising means for passing at least part of the liquid contained in said drum as the stream T(3) to the top of D. According to the present invention, it is preferred that the unit further comprises at least one (first) condensate drum CD(1) for the condensed stream removed from intermediate reboiler V(1a) and bottom reboiler V(1b), the unit more preferably further comprising means for passing at least part of a gas phase obtained in said first conden- sate drum CD(2) to V(2) and means for passing at least part of a liquid phase obtained in said first condensate drum CD(1) to a second condensate drum CD(2) as defined in the foregoing. In the context of the present invention, it is also conceivable that suitable reactive distillation col- umns K(i) are essentially bubble cap tray, valve tray and sieve tray columns. Specifically in the case of valve trays and sieve trays, the trays should be configured so that the raining-through of the liquid is minimized. A person skilled in the art will be familiar with the constructional measures required for this. It is also conceivable that the columns are provided with random packing elements or structured packings, with structured packings being preferred over random packing elements with a view to uniform distribution of the liquid. Further, it may be preferred that the unit further comprises means for separating an alkali metal methoxide A(i)OMe from at least one of the streams P(i). Preferably, the number of reactive dis- tillation columns K(i), n, is in the range of from 2 to 10, more preferably in the range of from 2 to 5, more preferably 2 or 3, more preferably 2.3rd aspect – Use In a third aspect, the invention relates to the use of a chemical production unit according to thesecond aspect of the invention described above or of a process according to the first aspect ofthe invention described above for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol, n being an integer with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methoxides A(i)OMe, and / or at least 2 of the mixtures P(i) comprise the same alkali metal alkoxide A(i)OMe at differ- ent concentrations. All details, embodiments and preferred embodiments described above in the section related to the first aspect of the invention or in the section related to the second aspect of the invention also apply for the third aspect of the invention. The present invention is further illustrated by the following set of embodiments and combina- tions of embodiments resulting from the dependencies and back-references as indicated. In par- ticular, it is noted that in each instance where a range of embodiments is mentioned, for exam- ple in the context of a term such as "The process of any one of embodiments 1 to 4", every em- bodiment in this range is meant to be explicitly disclosed for the skilled person, i.e. the wording of this term is to be understood by the skilled person as being synonymous to "The process ofany one of embodiments 1, 2, 3 and 4". Further, it is explicitly noted that the following set of em-bodiments is not the set of claims determining the extent of protection, but represents a suitably structured part of the description directed to general and preferred aspects of the present inven- tion.1. An integrated process for simultaneously preparing n mixtures P(i) comprising alkali metalmethoxide and methanol, comprising providing n reactive distillation columns K(i); providing n aqueous liquid streams H(i), a given stream H(i) comprising a dissolved alkali metal hydroxide A(i)OH, wherein n is an integer with n ≥ 2 and i = 1…n; andproviding a rectification column D comprising at least one reboiler V(1a); wherein the process comprises preparing the one or more alkali metal methoxides in the n reactive distillation column K(i) under reactive distillation conditions from the n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) com- prising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising (a) obtaining a vapor phase V comprising methanol at the top of the rectification columnD, said vapor phase V having a pressure pV and a temperature TV;(b) preparing at least two streams from the vapor phase V, comprising a vapor streamG having a pressure pG and a temperature TG with 0.95 ≤ pG / pV ≤ 1.00, and further comprising a stream T(1a), said stream T(1a) having a pressure pT(1a) and a temper-ature TT(1a) with pT(1a) > pV and TT(1a) > TV;(c) preparing the n streams G(i) from the vapor stream G, each of the streams G(i) hav-ing a pressure pG(i) and a temperature TG(i) with pG(i) > pG for each stream G(i); and feeding each stream G(i) into the respective reactive distillation column K(i); (d) passing at least a part of the stream T(1a) as a heating medium through the reboilerV(1a) of the rectification column D, obtaining a, preferably at least partially con-densed, stream TC(1a) having a temperature TTc(1a) with TTc(1a) < TT(1a);(e) feeding at least a part of the stream TC(1a) into the rectification column D;(f) feeding at least a first stream W(1) and a second stream W(2) at least partially intothe rectification column D, comprising (f.1) feeding at least a part of the stream W(1) into the lower part of the rectificationcolumn D at a position I(1); (f.2) feeding at least a part of the stream W(2) into the lower part of the rectificationcolumn D at a position I(2), wherein the position I(2) is located below the posi- tion I(1); wherein between the positions I(1) and I(2), the rectification column D is equipped with internals.2. The process of any one of embodiment 1, wherein below the position I(2) the rectificationcolumn D is equipped with internals.3. The process of any one of embodiments 1 or 2, wherein the rectification column D’s inter-nals are selected from tray, unstructured (random) packing, structured packing and mix- tures of two or more thereof.4. The process of any one of embodiments 1 to 3, wherein the rectification column D has inthe range of from 20 to 100, preferably in the range of from 30 to 80, more preferably in the range of from 40 to 60 theoretical trays.5. The process of embodiment 4, wherein position I(2) is located in the lower half of rectifica-tion column D, preferably third of rectification column D, wherein more preferably I(2) is located between the 4th and the 20th theoretical stage, more preferably between the 5thand the 15ththeoretical stage, more preferably between the 5thand the 12ththeoretical stage of the rectification column D, counted from the bottom.6. The process of embodiment 4 or 5, wherein position I(1) is located in the lower half of rec-tification column D, preferably in the lower third of rectification column D, wherein more preferably in the range of from 1 to 15 preferably of from 2 to 10, more preferably of from3 to 5, theoretical trays are present between the position I(2) and I(1).7. The process of any one of embodiments 1 to 6, further comprising for n reactive distillationcolumns K(i), feeding the stream G(i) into the lower part of the reactive distillation column K(i) and feeding the aqueous liquid stream H(i) into the upper part of the reactive distilla- tion column K(i).8. The process of any one of embodiments 1 to 7, wherein prior to preparing the n streamsG(i) from the vapor stream G according to (c), the stream G is passed through a compres- sor CG, thereby obtaining a compressed stream Gchaving a pressure pGc> pG9. The process of any one of embodiments 1 to 7, wherein prior to be fed into the reactivedistillation column K(i), each of the n streams G(i) is passed through a compressor C(i), thereby obtaining n compressed streams Gc(i) having a pressure pGc(i)with pGc(i)> pG.10. The process of any one of embodiments 1 to 9, wherein n = 2.11. The process of embodiment 10, wherein the stream H(1) comprises dissolved sodium hy-droxide and the stream H(2) comprises dissolved potassium hydroxide, wherein sodiummethoxide is prepared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is prepared in the reactive distillation column K(2) from which the stream W(2) is obtained.12. The process of embodiment 11, wherein the stream W(1) comprises methanol and waterat a molar methanol-to-water ratio r(1) and wherein the stream W(2) comprises methanoland water at a molar methanol-to-water ratio r(2) with r(2) < r(1).13. The process of any one of embodiments 1 to 12, further comprising feeding a stream Mcomprising methanol into the rectification column D at a position I(M).14. The process of embodiment 13, wherein the positions I(1) and I(2) are located below theposition I(M).15. The process of embodiment 14, wherein I(M) is in the upper half of rectification column D,preferably in the upper third of rectification column D; and I(1) and I(2) are located in the lower half of rectification column D.16. The process of any one of embodiments 1 to 15, wherein the rectification column D is op-erated at a pressure at the top of D in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs).17. The process of any one of embodiments 1 to 16, wherein the rectification column D is op-erated at a temperature at the top of D in the range of from 45 to 137 °C, preferably in therange of 49 to 118, more preferably in the range of from 64 to 111 °C, more preferably inthe range of from 64 to 95°C.18. The process of any one of embodiments 1 to 17, wherein the rectification column D is op-erated without top vapor recompression.19. The process of any one of embodiments 1 to 17, wherein the rectification column D is op-erated at a reflux ratio of at least 0.5:1, preferably in the range of from 0.55:1 to 1.4:1, ore preferably in the range of from 0.6:1 to 1.4:1.20. The process of embodiment 19, wherein the rectification column is operated with top va-por recompression.21. The process of embodiment 20, wherein realizing the reflux ratio comprises preparingfrom the vapor phase V a further vapor stream T(2), passing said stream T(2) through a condenser V(2), obtaining a liquid stream T(3) and a waste gas stream T(2w), and feeding the liquid stream T(3) into the top of the rectification column D.22. The process of embodiment 21, wherein the waste gas stream T(2w) essentially consistsof oxygen, nitrogen, carbon dioxide and methanol, wherein the amount of methanol inT(2w) is preferably in the range of from 2 to 80 weight-%, preferably in the range of from 10 to 30 weight-% based on the total weight of T(2w).23. The process of embodiment 21 or 22, wherein at least a part of Tc(1a) is fed to a conden-sate drum CD(1), wherein from said condensate drum CD(1), a gas stream T(1g) and aliquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) together with T(2) and said liquid stream T(1l) being combined with the liquid streamsT(2l) and (T2gl) in depressurized form, obtaining a combined liquid stream which is fed asthe stream T(3) into the top of the rectification column D.The process of any one of embodiments 1 to 23, wherein vapor phase V has a pressurepV, in the range of from 0.5 to 10 bar(abs), preferably in the range of from 0.75 to 6 bar(abs), more preferably in the range of from 1 to 5 bar(abs), more preferably in the range of from 1 to 3 bar(abs).The process of any one of embodiments 1 to 24, wherein vapor phase V has a tempera-ture TV in the range of from45 to 137 °C, preferably in the range of 49 to 118, more prefer-ably in the range of from 64 to 111 °C, more preferably in the range of from 64 to 95°C .The process of any one of embodiments 1 to 25, wherein a stream T(Di) having a temper-ature TT(Di)and a pressure pT(Di)is taken from the rectification column D and passed for heating purpose through the reboiler V(1a) of the rectification column D, obtaining aheated stream Th(Di) having a temperature TTh(Di) with TTh(Di) > TT(Di), wherein heatedstream Th(Di) is reintroduced into rectification column D.The process of embodiment 26, wherein V(1a) is an intermediate reboiler of the rectifica-tion column D and the stream T(Di) is preferably taken at an intermediate position from rectification column D.The process of any one of embodiments 1 to 27, wherein preparing the at least twostreams according to (b) comprises(b.1) splitting the vapor phase V into at least two vapor streams comprising thestream G and a vapor stream T(1) having a pressure pT(1) and a temperatureTT(1) with 0.95 ≤ pT(1) / pV ≤ 1.00;(b.2) preparing at least stream T(1a) from the vapor stream T(1), wherein for pre-paring the stream T(1a) a first compression unit CT(1) is employed.The process of embodiment 27 or 28, wherein stream T(1a) has a pressure pT(1a), which isadjusted so that TcondT(1a) is ≥ TboilT(Di) + 3 K, wherein TcondT(1a) is the condensation tempera-ture of stream T(1a) at a pressure pT(1a) and TboilT(Di) is the boiling temperature of streamT(Di) at a pressure pT(Di).The process of any one of embodiments 27 to 29, wherein stream T(1a) has a condensa-tion temperature TcondT(1a) which is in the range of from 3 to 30 K, preferably in the range offrom 4 and 25 K, more preferably in the range of from 5 and 20 K, higher than TboilT(Di).The process of any one of embodiments 1 to 30, wherein the rectification column D com-prises at least one reboiler V(1a) and at least one reboiler V(1b) and wherein the at leastone reboiler V(1a) is an intermediate reboiler and the at least one reboiler V(1b) is a bot- tom reboiler; wherein (b) comprises preparing at least three streams from the vapor phase V, compris- ing the vapor stream G having a pressure pGand a temperature TGwith 0.95 ≤ pG / pV≤ 1.00, and further comprising two streams T(1a) and T(1b), said stream T(1a) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pVand TT(1a)> TVand said stream T(1b) having a pressure pT(1b)and a temperature TT(1b)with with pT(1b)> pVand TT(1b)> TV; wherein (d) comprises(d.1) passing at least a part of the stream T(1a) as a heating medium through a reboilerV(1a), preferably an intermediate reboiler V(1a), of the rectification column D, ob-taining a stream TC(1a) having a temperature TTc(1a)with TTc(1a)< TT(1a);(d.2) passing at least a part of the stream T(1b) as a heating medium through a reboilerV(1b), preferably a bottom reboiler V(1a), of the distillation column D, obtaining astream TC(1b) having a temperature TTc(1b)with TTc(1b)< TT(1b); and wherein (e) comprises(e.1) feeding at least a part of the stream TC(1a) into the rectification column D;(e.2) feeding at least a part of the stream TC(1b) into the rectification column D.The process of embodiment 31, wherein preparing the at least three streams according to(b) comprises(b.1) splitting the vapor phase V into at least two vapor streams comprising the stream Gand a vapor stream T(1) having a pressure pT(1) and a temperature TT(1) with 0.95 ≤ pT(1) / pV ≤ 1.00;(b.2) preparing at least the two streams T(1a) and T(1b) from the vapor stream T(1).The process of embodiment 31 or 32,wherein a stream T(Di) is taken from the rectification column D at an intermediate position and passed for heating purpose through an intermediate reboiler V(1a) of the rectificationcolumn D, obtaining a heated stream Th(Di) having a temperature TTh(Di) with TTh(Di) > TT(Di),wherein heated stream Th(Di) is reintroduced into rectification column D; andwherein a stream T(Db) is taken from the rectification column D at a bottom position and passed for heating purpose through the bottom reboiler V(1b) of the rectification columnD, obtaining a stream Th(Db) having a temperature TTh(Db) with TTh(Db) > TT(Db), whereinheated stream Th(Db) is reintroduced into rectification column D.34. The process of any one of embodiments 31 to 33, wherein stream T(1b) has a pressurepT(1b) ,which is adjusted so that TcondT(1b) is ≥ TboilT(Db) + 3 K, wherein TcondT(1b) is the conden-sation temperature of stream T(1b) at a pressure pT(1b) and TboilT(Db) is the boiling tempera-ture of stream T(Db) at a pressure pT(Db).35. The process of any one of embodiments 31 to 34, wherein T(1b) has a condensation tem-perature TcondT(1b) which is in the range of from 3 to 30 K, preferably in the range of from 4and 25 K, more preferably in the range of from 5 and 20 K, higher than TboilT(Db.36. A chemical production unit for carrying out the process according to any one of embodi-ments 1 to 35, comprising -a rectification column D comprising-- in its lower part, inlet means for feeding streams W(i) or one or more com-bined stream thereof into D; -- in its upper part, outlet means for removing a vapor stream V or dividedstreams thereof, comprising at least a gaseous stream G and at a stream T(1a), from the top of D; -- at least one reboiler V(1a);- optionally a stream dividing device So for dividing V or substreams of V into (further)sub streams thereof; -a first compressor CT(1) for compressing T(1a) or a part thereof;- means for passing compressed sub streams of T(1) from CT(1) as heating mediumthrough reboiler V(1a); -a stream dividing device S for dividing the stream G into n streams G(i);- means for passing the stream G to said stream dividing device S;- n reactive distillation columns K(i), n≥2 and i=1…n; said reactive distillation columnsK(i) being arranged in parallel, each reactive distillation column K(i) comprising -- in its upper part, preferably in its top, inlet means for feeding a stream H(i) intoK(i); -- in its lower part, inlet means for feeding a stream G(i) into K(i);-- outlet means for removing a stream W(i) from the top of K(i);-- a bottom reboiler;-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms streamremoved from K(i); -means for passing the streams G(i) to the reactive distillation columns K(i);- spatially separated means for passing at least one of the streams W(i) and at leastanother one of the streams W(i) at different positions to the rectification column D; -one or more compressors C(i) for compressing either the stream G and / or thestreams G(i) and / or the streams W(i).37. The chemical production unit of embodiment 36, comprising an intermediate reboilerV(1a) and a bottom reboiler V(1b), further comprising a second compressor CT(2) for com-pressing T(1b); means for passing compressed sub streams of T(1) from CT(2) as heatingmedium through bottom reboiler V(1b).38. The chemical production unit of embodiment 36 or 37 comprising means for passing con-densed sub streams of T(1a) and optionally of T(1b) after passage through intermediate reboiler V(1a) and optionally through bottom reboiler V(1b) into D, the means preferablycomprising -at least one condenser, preferably a condenser V(2) and optionally a furthercondenser V(3) arranged downstream of V(2), having inlet means for receiving condensed stream of T(1a) after passage through intermediate reboiler V(1a)and optionally condensed stream T(1b) after passage through bottom reboilerV(1b), and having outlet means for removing a condensed stream T(3) and for removing a waste gas stream; -inlet means for feeding the stream T(3) to the top of D.39. The chemical production unit of any one of embodiments 36 to 38 comprising inlet meansfor feeding a methanol stream M into D.40. Use of a chemical production unit according to any one of embodiments 36 to 39 or of aprocess according to any one of embodiments 1 to 35 for simultaneously producing n mix- tures P(i) comprising alkali metal methoxide and methanol, n being an integer with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methoxides A(i)OMe, and / or at least 2 of the mixtures P(i) comprise the same alkali metal alkoxide A(i)OMe at different concentrations. The present invention is further illustrated by the following reference examples, comparative ex- amples, and examples. Examples1. Reference Example 1: Simultaneous production of sodium methoxide and potas-sium methoxide without top vapor recompression in rectification column D Fig.2 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH anda mixture P(2) comprising KOMe and MeOH according to Reference Example 1. Regarding theoperating conditions of the distillation column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 1a below. Regarding the relative mass flow rates, reference is made to Table 1b below. Table 1a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Column DTemperature at the bottom / °C 124Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 1bRelationships between the mass flow rates f of the different streamsDefinition of Specified: H(1), H(2) streams M(1), M(2): part of condensate from V(2) H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55Ratios of f(M(2)) / f(H(2)) 0.40mass flow rates f(T(3)) / f(G) *) 0.92of streams f(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According tothis calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1),fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)1.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg1.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg1.3 fMeOH(water) = 0.001 * f(water) (maximum value)1.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water(bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the watercontents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.1.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:1.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg1.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg1.5.3 fH2O(M) = 0.001 * f(M)1.5.4 fH2O(waste gas) = 0 (neglected)2. Reference Example 2: Simultaneous production of sodium methoxide and potas-sium methoxide with top vapor recompression (first compression unit) for intermediate reboiler in rectification column D Fig.3 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH anda mixture P(2) comprising KOMe and MeOH according to Reference Example 2. Regarding theoperating conditions of the rectification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 2a below. Regarding the relative mass flow rates, refer- ence is made to Table 2b below. The use of vapor recompression reduces the energy demand of the distillation in rectification column D considerably. It is possible to have a ratio of the heat streams to V(1b) and V(1a) of about 1:4. That means, the energy demand decreases to 20 %. But about 10 % (depending on the pressure) of the energy which is transferred in V(1a) is needed as power for the compressor CT(1). All in all, there is already some energy saving by using vapor recompression. Table 2a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Column D Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 2b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from V(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.3f(G(2)) / f(H(2)) 9.03f(M(1)) / f(H(1)) 0.55Ratios off(M(2)) / f(H(2)) 0.40mass flow ratesf(T(3)) / f(G) *) 1.0of streamsf(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 3.97*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water.P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water.In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected. According to this calculation, fMeOH(P(1)) is the mass flow rate of MeOH contained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) is the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)2.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg2.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg2.3 fMeOH(water) = 0.001 * f(water) (maximum value)2.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water(bottom stream of D, waste water stream), f(water), is calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, are neglected.2.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:2.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg2.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg2.5.3 fH2O(M) = 0.001 * f(M)2.5.4 fH2O(waste gas) = 0 (neglected)3. Example 1: (f.1) Feeding W(1) into rectification column D at a position I(1) combinedwith feeding the stream W(2) into rectification column D at a position I(2) As shown in Fig.4, the stream W(1) was fed into the lower part of the rectification column D at a position I(1) and the stream W(2) was fed into the lower part of the rectification column D at a position I(2), wherein the position I(2) was located below the position I(1) and the rectification column D was equipped with internals between the positions I(1) and I(2). The use of vapor recompression reduces the energy demand of the distillation in rectification column D considerably. It was possible to have a ratio of the heat streams to V(1b) and V(1a) of about 1:4. That means, the energy demand decreased to 20 %. But about 10 % (depending on the pressure) of the energy which was transferred in V(1a) was needed as power for the com- pressor CT(1). All in all, there was a large energy saving by using vapor recompression. The advantage in comparison to Reference Example 2 was a smaller water concentration (mi- nus 11%) at the top of the rectification column D and this resulted in a better product quality of the sodium methylate solution (water concentration in sodium methylate solution decreased by4.44% in relation to Reference Example 2) and also an at least equal product quality of the po-tassium methylate solution in that the water content is not elevated but rather at least main-tained about unchanged in relation to Reference Example 2. Fig.4 shows the process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) comprising KOMe and MeOH. Regarding the operating conditions of the rec- tification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 3a below. Regarding the relative mass flow rates, reference is made to Table 3b below. Table 3a Operating conditions of the columns D, K(1) and K(2) Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Column DTheoretical stages 50W(1) to theoretical stage from bottom 11th W(2) to theoretical stage from bottom 8th Mfed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 5Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 40Pressure at the top / bar(abs) 2.15Temperature at the top / °C 89Column K(2)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 116Number of trays 40Table 3b Relationships between the mass flow rates f of the different streams Specified: H(1), H(2) Definition of M(1), M(2): part of condensate from V(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water Ratios of f(G(1)) / f(H(1)) 13.3 mass flow ratesf(G(2)) / f(H(2)) 9.03of streamsf(M(1)) / f(H(1)) 0.55f(M(2)) / f(H(2)) 0.40f(T(3)) / f(G) *) 1.0f(P(1)) / f(H(1)) 2.25f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 3.97*) f(G) = f(G(1)) + f(G(2)) P(1): 30 weight-% of sodium methoxide in methanol, < 1000 ppm of water. P(2): 32 weight-% of potassium methoxide in methanol, < 1000 ppm of water. In the following, it is indicated how the mass flow rate of the methanol contained in the stream M (methanol balance, fresh methanol stream), fMeOH(M), was calculated. In this calculation, the wa- ter contents of P(1) and P(2), both being less than 1000 weight-ppm, were neglected. Accordingto this calculation, fMeOH(P(1)) was the mass flow rate of MeOH contained in the stream P(1),fMeOH(P(2)) was the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) was the mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) was the mass flow rate of MeOH contained in the waste gas stream: fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas)3.1 fMeOH(P(1)) = [(1-cNaOME) * f(P(1))] + [(MMeOH / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kgcNaOMe in P(1) 0.3 kg / kg3.2 fMeOH(P(2)) = [(1-cKOMe) * f(P(2))] + [(MMeOH / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMMeOH 32 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kgcKOMe in P(2) 0.32 kg / kg3.3 fMeOH(water) = 0.001 * f(water) (maximum value)3.4 fMeOH(waste gas) = 0 (neglected)In the following, it is indicated how the mass flow rate of the water contained in the stream water (bottom stream of D, waste water stream), f(water), was calculated. In this calculation, the water contents of P(1) and P(2), both being less than 1000 weight-ppm, were neglected.3.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) is the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) is the mass flow rate of water contained in the stream H(2) and fH2O(M) is the mass flow rate of water contained in the stream M:3.5.1 fH2O(H(1)) = [(1-cNaOH) * f(H(1))] + [(MH2O / MNaOH * cNaOH) * f(H(1))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMNaOH 40 kg / kmolcNaOH in H(1) 0.5 kg / kg3.5.2 fH2O(H(2)) = [(1-cKOH) * f(H(2))] + [(MH2O / MKOH * cKOH) * f(H(2))]Molecular mass M / concentration c values unitsMH2O 18 kg / kmolMKOH 56 kg / kmolcKOH in H(2) 0.48 kg / kg3.5.3 fH2O(M) = 0.001 * f(M)3.5.4 fH2O(waste gas) = 0 (neglected) Short description of the FiguresFig.1 shows a schematic overview of a process according to the present inventionwherein a vapor phase V comprising methanol is obtained at the top of the rectification column D. From said vapor phase V, at least two streams are prepared, comprising a vapor stream G and further comprising a stream T(1a). The gas stream G, exhibiting a flow rate f(G), is passed through a compressor CG, and the thus compressed stream is then divided into two compressed streams G(1) and G(2), both having the same composition as G. The stream G(1) exhibits a flow rate f(G(1)), the stream G(2) exhibits a flow rate f(G(2)), wherein f(G(1))+f((G2))=f(G). The compressed stream G(1) is fed into the lower part of reactive distillation column K(1), wherein into the upper part of K(1), a liquid aqueous stream H(1) comprising a dissolved alkali metal hy- droxide A(1)OH is fed. K(1) is equipped with a bottom reboiler VK(1). The bottoms stream re- moved from the column K(1) is the mixture P(1) comprising alkali metal methoxide A(1)OMe and methanol. From the top of the column K(1), which is operated without reflux, a gas stream W(1) essentially consisting of methanol and water is removed, wherein W(1) is fed into a lower part of the rectification column D. The compressed stream G(2) is then fed into the lower part of reactive distillation column K(2), wherein into the upper part of K(2), a liquid aqueous stream H(2) comprising a dissolved alkali metal hydroxide A(2)OH is fed. K(2) is equipped with a bot- tom reboiler VK(2).The bottoms stream from K(2) is the mixture P(2) comprising alkali metal methoxide A(2)OMe and methanol. From the top of the column K(2), which is operated withoutreflux, a gas stream W(2) essentially consisting of methanol and water is removed, whereinW(2) is fed, separated from W(1), into a lower part of the rectification column D. W(1) is fed into the lower part of the rectification column D at a position I(1) and stream W(2) is fed into the lower part of the rectification column D at a position I(2), wherein the position I(2) is located be- low the position I(1). The rectification column D is equipped with internals between the positions I(1) and I(2).The stream T(1a) having a temperature TT(1a) is passed as a heating medium through an inter-mediate reboiler V(1a) of the rectification column D, thereby obtaining a condensed streamTC(1a) having a temperature TTc(1a) with TTc(1a) < TT(1a) and stream TC(1a) is passed into the recti-fication column D as outlined in detail below and shown in the Figure. Intermediate reboilerV(1a) is supplemented by sump reboiler V(1b) at the bottom of rectification column D.The realization of the reflux ratio for rectification column D is shown in the upper part of Fig. 1,wherein realizing the reflux ratio comprises preparing from the vapor phase V a further vapor stream T(2), passing said stream T(2) through a condenser V(2), obtaining a liquid stream T(3) and a waste gas stream T(2w), and feeding the liquid stream T(3) into the top of the rectification column D. Stream Tc(1a) is fed to a first condensate drum CD(1), wherein from said first con- densate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in a second condensate drum CD(2) in depressurizedform, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the recti-fication column D.Fig.2 shows a schematic overview of a comparative process, without compressionunits as used in Reference Example 1.Fig.3 shows a schematic overview of a comparative process, with only a first com-pression unit CT(1) as used in Reference Example 2. Everything is identical as described above in detail for Fig.1, with the difference that the gas stream G, exhibiting a flow rate f(G), is first divided into two streams G(1) and G(2), which are then each passed through a compressorCG(1) and CG(2) respectively, and the thus compressed streams GC(1) and GC(2), both havingthe same composition as G are fed into the lower part of reactive distillation column K(1) andK(2) respectively. The further difference compared to Fig. 1 is that streams W(2) and W(1) arefeed into a lower part of the rectification column D, wherein the feeding is done separately but atabout the same height of D1, without any physical separation between the feeding points. Theremaining process is as described in Fig. 1 above.Fig.4 shows a schematic overview of the process of Example 1 as in Fig.1, whereinthe stream W(1) is fed into the lower part of the rectification column D at a position I(1) and the stream W(2) is fed into the lower part of the rectification column D at a position I(2), wherein the position I(2) is located below the position I(1) and the rectification column D is equipped with in-ternals between the positions I(1) and I(2). Contrary to Fig.1 (but identical to Fig.3), the streamG is not compressed in a compressor CG but rather separated into two streams G(1) and G(2), wherein each of G(1), G(2) is passed through a compressor CG(1), CG(2) before being passed into the respective reactive distillation column K(1), K(2). The remaining process is as described in Fig.1 above. Cited Literature -US 2002 / 0183566 A1- US 2008 / 0296786 A1- WO 2013 / 168113 A1- WO 2021 / 148174 A1- WO 2022 / 117803 A1- WO 2022 / 263032 A1

Claims

Claims1. An integrated process for simultaneously preparing n mixtures P(i) comprising alkali metalmethoxide and methanol, comprising providing n reactive distillation columns K(i); providing n aqueous liquid streams H(i), a given stream H(i) comprising a dissolved alkali metal hydroxide A(i)OH, wherein n is an integer with n ≥ 2 and i = 1…n; and providing a rectification column D comprising at least one reboiler V(1a); wherein the process comprises preparing the one or more alkali metal methoxides in the nreactive distillation column K(i) under reactive distillation conditions from the n streams H(i) and n streams G(i) comprising methanol, thereby obtaining n top streams W(i) com- prising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising (a) obtaining a vapor phase V comprising methanol at the top of the rectification columnD, said vapor phase V having a pressure pVand a temperature TV; (b) preparing at least two streams from the vapor phase V, comprising a vapor stream G having a pressure pG and a temperature TG with 0.95 ≤ pG / pV ≤ 1.00, and further comprising a stream T(1a), said stream T(1a) having a pressure pT(1a) and a temper- ature TT(1a)with pT(1a)> pVand TT(1a)> TV; (c) preparing the n streams G(i) from the vapor stream G, each of the streams G(i) hav-ing a pressure pG(i)and a temperature TG(i)with pG(i)> pGfor each stream G(i); and feeding each stream G(i) into the respective reactive distillation column K(i); (d) passing at least a part of the stream T(1a) as a heating medium through the reboilerV(1a) of the rectification column D, obtaining a, preferably at least partially con- densed, stream TC(1a) having a temperature TTc(1a) with TTc(1a) < TT(1a); (e) feeding at least a part of the stream TC(1a) into the rectification column D;(f) feeding at least a first stream W(1) and a second stream W(2) at least partially intothe rectification column D, comprising (f.1) feeding at least a part of the stream W(1) into the lower part of the rectificationcolumn D at a position I(1); (f.2) feeding at least a part of the stream W(2) into the lower part of the rectificationcolumn D at a position I(2), wherein the position I(2) is located below the posi- tion I(1); wherein between the positions I(1) and I(2), the rectification column D is equipped with internals.

2. The process of any one of claim 1, wherein below the position I(2) the rectification columnD is equipped with internals.

3. The process of claim 1or 2, wherein the rectification column D has in the range of from 20to 100, preferably in the range of from 30 to 80, more preferably in the range of from 40 to 60 theoretical trays.

4. The process of claim 3, wherein position I(2) is located in the lower half of rectification col-umn D, preferably in the lower third of rectification column D, wherein more preferably I(2) is located between the 4thand the 20ththeoretical stage, more preferably between the 5thand the 15ththeoretical stage, more preferably between the 5thand the 12ththeoretical stage of the rectification column D, counted from the bottom.

5. The process of claim 3 or 4, wherein position I(1) is located in the lower half of rectificationcolumn D, preferably in the lower third of rectification column D, wherein more preferably in the range of from 1 to 15 preferably of from 2 to 10, more preferably of from 3 to 5, the- oretical trays are present between the position I(2) and I(1).

6. The process of any one of claims 1 to 5, further comprising for n reactive distillation col-umns K(i), feeding the stream G(i) into the lower part of the reactive distillation column K(i) and feeding the aqueous liquid stream H(i) into the upper part of the reactive distillation column K(i).

7. The process of any one of claims 1 to 6, wherein a stream H(1) comprises dissolved so-dium hydroxide and a stream H(2) comprises dissolved potassium hydroxide, wherein so- dium methoxide is prepared in a reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is prepared in a reactive distillation column K(2) from which the stream W(2) is obtained.

8. The process of claim 7, wherein the stream W(1) comprises methanol and water at a mo-lar methanol-to-water ratio r(1) and wherein the stream W(2) comprises methanol and wa- ter at a molar methanol-to-water ratio r(2) with r(2) < r(1).

9. The process of any one of claims 1 to 8, further comprising feeding a stream M compris-ing methanol into the rectification column D at a position I(M).

10. The process of claim 9, wherein the positions I(1) and I(2) are located below the positionI(M).

11. The process of claim 9 or 10, wherein I(M) is in the upper half of rectification column D,preferably in the upper third of rectification column D; and I(1) and I(2) are located in the lower half of rectification column D.

12. The process of any one of claims 1 to 11, wherein preparing the at least two streams ac-cording to (b) comprises (b.1) splitting the vapor phase V into at least two vapor streams comprising thestream G and a vapor stream T(1) having a pressure pT(1)and a temperature TT(1)with 0.95 ≤ pT(1) / pV≤ 1.00; (b.2) preparing at least stream T(1a) from the vapor stream T(1), wherein for pre-paring the stream T(1a) a first compression unit CT(1) is employed.

13. The process of any one of claims 1 to 12, wherein the rectification column D comprises atleast one reboiler V(1a) and at least one reboiler V(1b) and wherein the at least one re- boiler V(1a) is an intermediate reboiler and the at least one reboiler V(1b) is a bottom re- boiler; wherein (b) comprises preparing at least three streams from the vapor phase V, compris- ing the vapor stream G having a pressure pG and a temperature TG with 0.95 ≤ pG / pV ≤ 1.00, and further comprising two streams T(1a) and T(1b), said stream T(1a) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pVand TT(1a)> TVand said stream T(1b) having a pressure pT(1b)and a temperature TT(1b)with with pT(1b)> pVand TT(1b)> TV; wherein (d) comprises (d.1) passing at least a part of the stream T(1a) as a heating medium through a reboilerV(1a) of the rectification column D, obtaining a stream TC(1a) having a temperature TTc(1a) with TTc(1a) < TT(1a); (d.2) passing at least a part of the stream T(1b) as a heating medium through a reboilerV(1b) of the distillation column D, obtaining a stream TC(1b) having a temperature TTc(1b) with TTc(1b) < TT(1b); and wherein (e) comprises (e.1) feeding at least a part of the stream TC(1a) into the rectification column D;(e.2) feeding at least a part of the stream TC(1b) into the rectification column D.

14. A chemical production unit for carrying out the process according to any one of claims 1 to13, comprising -a rectification column D comprising-- in its lower part, inlet means for feeding streams W(i) or one or more com-bined stream thereof into D;-- in its upper part, outlet means for removing a vapor stream V or dividedstreams thereof, comprising at least a gaseous stream G and at a stream T(1a), from the top of D; -- at least one reboiler V(1a);- optionally a stream dividing device So for dividing V or substreams of V into (further)sub streams thereof; -a first compressor CT(1) for compressing T(1a) or a part thereof;- means for passing compressed sub streams of T(1) from CT(1) as heating mediumthrough intermediate reboiler V(1a); -a stream dividing device S for dividing the stream G into n streams G(i);- means for passing the stream G to said stream dividing device S;- n reactive distillation columns K(i), n≥2 and i=1…n; said reactive distillation columnsK(i) being arranged in parallel, each reactive distillation column K(i) comprising -- in its upper part, preferably in its top, inlet means for feeding a stream H(i) intoK(i); -- in its lower part, inlet means for feeding a stream G(i) into K(i);-- outlet means for removing a stream W(i) from the top of K(i);-- a bottom reboiler;-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms streamremoved from K(i); -means for passing the streams G(i) to the reactive distillation columns K(i);- spatially separated means for passing at least one of the streams W(i) and at leastanother one of the streams W(i) at different positions to the rectification column D; -one or more compressors C(i) for compressing either the stream G and / or thestreams G(i) and / or the streams W(i).

15. Use of a chemical production unit according to claim 14 or of a process according to anyone of claims 1 to 13 for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol, n being an integer with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methoxides A(i)OMe, and / or at least 2 of the mixtures P(i) comprise the same alkali metal alkoxide A(i)OMe at different concentrations.

Images