Integrated process for simultaneously preparing n mixtures comprising alkali metal methoxide and methanol and for preparing solid alkali metal methoxide

Abstract

In a first aspect, the invention relates to an integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide and methanol and for preparing solid alkali metal methoxide A(i)OMe, 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; 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) comprising methanol and water; and obtaining n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol; the process further comprising (a) subjecting at least a part of at least one of the n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol in a separation unit SU to a solid separation, obtaining a residue enriched in alkali metal methoxide A(i)OMe compared to P(i), preferably containing solid alkali metal methoxide A(i)OMe, and a stream MR(i) comprising methanol; and (b) feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to at least one reactive distillation column K(i) and / or feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to rectification column D. A second aspect of the invention is directed to a chemical production unit for carrying out the process according to the first aspect of the invention. In a third aspect, the invention relates to a use of the chemical production unit according to the second aspect of the invention or of a process according to the first aspect of the invention 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.

Description

[0001]Integrated process for simultaneously preparing n mixtures comprising alkali metal methoxide and methanol and for preparing solid alkali metal methoxide In a first aspect, the invention relates to an integrated process for simultaneously preparing n mixtures P(i) compris- ing alkali metal methoxide and methanol and for preparing solid alkali metal methoxide A(i)OMe, the process com- prising (a) subjecting at least a part of at least one of the n mixtures P(i) comprising alkali metal methoxide A(i)OMe and methanol (n bottoms streams P(i) in a separation unit SU to a solid separation, obtaining a residue enriched in alkali metal methoxide A(i)OMe compared to P(i), preferably containing solid alkali metal methoxide A(i)OMe, and a stream MR(i) comprising methanol; and (b) feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to at least one reactive distillation column K(i) and / or feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to rectification column D. A second aspect of the invention is directed to a chemical production unit for carrying out the process according to the first aspect of the invention. In a third aspect, the invention relates to a use of the chemical production unit according to the second aspect of the invention or of a process according to the first aspect of the invention 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. State of the art In the prior art, processes are described wherein a mixture comprising an alkali metal alkoxide and methanol is pre- pared in a reactive distillation column from a methanol stream and an aqueous stream which comprises a dissolved alkali metal hydroxide, for example, US 2002 / 0183566 A1. However, such a process enables only to produce one specific mixture comprising alkali metal methoxide and methanol. Processes for simultaneously preparing two mix- tures comprising sodium metal alkoxide and potassium metal alkoxide as well as methanol are also known, for exam- ple, from WO 2021 / 148174 A1, WO 2022 / 263032 A1, or WO 2022 / 117803 A1. Regarding the alkali metal alkoxides, it is usual to get them from the respective methanolic solutions by removal of methanol, for example, by crystalliza-tion. EP 1965879 A1 discloses a method of isolating alkoxides by crystallization from a solution in the correspond-ing alcohol. In the crystallization process, methanol is evaporated, which however is still contaminated by the respec- tive alkali metal alkoxide due to entrainment and therefore cannot be used for another purpose. Furthermore, this results in a considerable loss of crystallized alkali metal alkoxide, typically in the range of about 1 to 2 weight-% com- pared to the maximum possible crystallisation yield. The concentration of the alkali metal alkoxide in the top conden- sate of the evaporation can only be partially influenced by the installation of demisters, so that a reduction of the loss to a negligible level is difficult and would require complex purification respectively, which could be achieved, for ex- ample, by distillation. However, this would require an additional process step, which would also result in cost in- crease.Thus, there is still a need for improvement, both in terms of avoidance of loss of valuable product and in terms of effi-ciency and apparatus costs.Surprisingly, it was found that these objects can be solved by an integrated process as described below, in which amixture comprising an alkali metal alkoxide and methanol is prepared in a reactive distillation column from a metha- nol stream and an aqueous stream which comprises a dissolved alkali metal hydroxide, wherein at least a part of atleast one of the bottoms streams comprising alkali metal methoxide and methanol from such a reactive distillationcolumn is subjected in a separation unit to a solid separation, obtaining a residue enriched in alkali metal methoxideand a stream comprising methanol; and at least a part of the stream comprising methanol obtained is fed to at leastone reactive distillation column and / or to a connected rectification column, loss of the valuable product could be sig- nificantly reduced, and in some constellations also corrosion of the equipment used could be reduced or avoided.In a first aspect, the invention thus relates to an integrated process for simultaneously preparing n mixtures P(i) com-prising alkali metal methoxide and methanol and for preparing solid alkali metal methoxide A(i)OMe, 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; 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) comprising methanol and water; and obtaining n mixtures P(i) comprising alkali metalmethoxide A(i)OMe and methanol as bottoms streams (bottoms streams P(i));the process further comprising(a) subjecting at least a part of at least one of the n bottoms streams P(i) comprising alkali metal methoxideA(i)OMe and methanol in a separation unit SU to a solid separation, obtaining a residue enriched in alkali metal methoxide A(i)OMe compared to P(i), preferably containing solid alkali metal methoxide A(i)OMe, and a stream MR(i) comprising methanol;(b) feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to at least one reactive distilla-tion column K(i) and / or feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to recti- fication column D. MR(i) is preferably fed in (b) as a liquid stream.In some preferred embodiments of the integrated process, the obtained solid alkali metal methoxide A(i)OMe is atleast partially, more preferably completely, crystalline. Feeding at least a part of the stream comprising methanolMR(i) obtained in (a) to at least one reactive distillation column K(i), instead of, for example, feeding it to the rectifica- tion column D, allows in cases where the stream MR(i) comprises a certain amount of alkali metal methoxide to in- crease the alkali metal methoxide yield, especially in the residue enriched in alkali metal methoxide A(i)OMe ob-tained in (a), and avoids the drawback that residual amounts of alkali methylate contained in MR(i) react in the rectifi-cation column D back to alkali hydroxide. As a rectification column is normally made from steel, which is sensitive to corrosion, avoiding alkali hydroxide formation in turn helps to avoid corrosion of the rectification column D, thus im- proving the shelf life of the equipment used. In case of MR(i) being free of alkali metal methoxide, the recycling of MR(i) directly into D enables an efficient process.In some preferred embodiments of the integrated process, in (a), in the range of from 10 to 100 weight-% of at leastone of the n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol are subjected in the sep- aration unit SU to solid separation, based on the total weight of the at least one of the n bottom streams P(i) being 100 weight-%.In some preferred embodiments of the integrated process, in (b), at least 50 weight-%, preferably at least 60 weight-%, more preferably at least 70 weight-%, more preferably at least 80 weight-%, more preferably at least 90 weight-%, more preferably at least 95 weight-%, more preferably at least 98 weight-%, more preferably at least 99 weight-%, more preferably at least 99.5 weight-%, of the stream comprising methanol MR(i) obtained in (a) are fed to at least one reactive distillation column K(i) and / or to rectification column D.In some preferred embodiments of the integrated process, the solid separation in (a) is done by at least partial evap-oration, wherein the separation unit SU is preferably an evaporation unit or a partial evaporation unit. In some pre-ferred embodiments of the integrated process, the separation unit SU is an evaporation unit, which is preferably a unit, in which an evaporation of the at least a part of at least one of the n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol up to dryness takes place. From said evaporation (unit), a stream compris- ing methanol MR(i) and a solid comprising alkali metal methoxide A(i)OMe are obtained. The evaporation unit is pref- erably selected from kneader, paddle dryer, screw dryer, vacuum dryer and mixtures of two or more of these dryer types. A kneader is preferably a kneaderreactor, more preferably a single-shaft kneaderreactor or a twin-shaftkneaderreactor, commercially available from the company LIST Technology AG (Switzerland). More preferably, theseparation unit SU comprises at least a paddle dryer. As indicated above, MR(i) is preferably fed in (b) as a liquid stream, so that after evaporation, a condensation takes place to obtain MR(i) in liquid form, before feeding accordingto b) is done. Condensation is done in an apparatus, operated with a cooling medium, wherein condensation is pref-erably complete. Thus, preferably, the stream MR(i) is fed in (b) to at least one reactive distillation column K(i) and / orto rectification column D as a liquid stream, wherein preferably, the stream MR(i) comprising methanol obtained in (a)is subjected to condensation, thereby obtaining MR(i) in liquid form; wherein condensation is preferably done in anapparatus operated with a cooling medium, wherein condensation is more preferably complete. Feeding of MR(i) ingaseous or partially gaseous form is however possible. Solid alkali metal methoxide A(i)OMe is separated by filtra-tion, optionally followed by drying.In some preferred embodiments of the integrated process, the separation unit SU is a partial evaporation unit, whichis preferably a unit, in which a partial evaporation of the at least a part of at least one of the n bottoms streams P(i)comprising alkali metal methoxide A(i)OMe and methanol takes place. From said partial evaporation (unit), a streamcomprising methanol MR(i), a solid and a solution are obtained, wherein the solution still comprises a part of the alkalimetal methoxide A(i)OMe in dissolved form (saturated solution), a further part of the alkali metal methoxide A(i)OMebeing comprised in the solid. The temperature T of the obtained solution, which still comprises a part of the alkalimetal methoxide A(i)OMe in dissolved form, is optionally then reduced to a temperature Tred. with T > Tred., the tem-perature reduction optionally resulting in obtaining a further part of alkali metal methoxide A(i)OMe as solid and a so-lution still comprising a part of the alkali metal methoxide A(i)OMe in dissolved form (saturated solution). The remain-ing solution having temperature T or Tred., which still comprises a part of the alkali metal methoxide A(i)OMe, is thenpreferably at least partially or completely recycled back into the partial evaporation unit, wherein optionally a partthereof is recycled into K(i). The stream comprising methanol MR(i), obtained from the partial evaporation (unit), is fedin b) to at least one reactive distillation column K(i) and / or to rectification column D. As indicated above, MR(i) is pref- erably fed in (b) as a liquid stream, so that after evaporation, a condensation takes place to obtain MR(i) in liquidform, before feeding according to b) is done. Condensation is done in an apparatus, operated with a cooling medium,wherein condensation is preferably complete. Feeding of MR(i) in gaseous or partially gaseous form is however pos-sible. Solid alkali metal methoxide A(i)OMe is separated by filtration, optionally followed by drying.In some preferred embodiments of the integrated process, the solid separation in (a) is done at a pressure in therange of from 0.5 to 5 bar(abs), preferably in the range of from 0.6 to 4 bar(abs), more preferably in the range of from0.7 to 3 bar(abs), more preferably in the range of from 0.8 to 1.5 bar(abs). In some preferred embodiments of the in-tegrated process, the solid separation in (a) is done at a temperature in the range of from 50 to 200 °C, preferably inthe range of from 60 to 180°C, more preferably in the range of from 65 to 160°C. In some preferred embodiments of the integrated process, the residue enriched in alkali metal methoxide A(i)OMe compared to P(i) comprises at the outmost 10 weight-%, preferably at the outmost 5 weight-%, more preferably at theoutmost 1 weight-% of methanol, based on the total weight of the residue being 100 weight-%. As indicated above,the residue enriched in alkali metal methoxide A(i)OMe preferably contains solid alkali metal methoxide A(i)OMe, wherein “solid” comprises crystalline as well as amorphous state. Preferably, in the range of from 95 to 100 weight-% of the residue enriched in alkali metal methoxide A(i)OMe are solid based on the total weight of the residue being 100 weight-%, wherein the residual methanol is preferably comprised at least partially as crystal methanol.In some preferred embodiments of the integrated process, the stream MR(i) comprises less than 0.1 weight-%, morepreferably less than 0.01 weight-%, more preferably less than 0.001 weight-% of alkali metal methoxide A(i)OMe,based on the total weight of the stream MR(i) being 100 weight-%, wherein in (b), preferably at least a part of the stream comprising methanol MR(i) obtained in (a) is fed to rectification column D, more preferably the stream com-prising methanol MR(i) obtained in (a) is fed to rectification column D. Preferably, MR(i) has a methanol concentrationcMeOH(MR(i)) and is fed to rectification column D at a position P(1), where the MeOH concentration at that positionP(1) within the rectification column D cMeOH(P1) is preferably about equal to cMeOH(MR(i)) with 0.95 ≤ cMeOH(MR(i)) / cMeOH(P1) ≤ 1.05.In some preferred embodiments of the integrated process, the stream MR(i) comprises in the range of from 0.001 to10 weight-%, preferably in the range of from 0.005 to 5 weight-%, more preferably in the range of from 0.01 to 2 weight-% of alkali metal methoxide A(i)OMe, based on the total weight of the stream MR(i) being 100 weight-%,wherein in (b), preferably at least a part of the stream comprising methanol MR(i) obtained in (a) is fed to at least onereactive distillation column K(i), more preferably the stream comprising methanol MR(i) obtained in (a) is fed to the same reactive distillation column K(i) from which the bottoms stream P(i) comprising alkali metal methoxide A(i)OMeand methanol, subjected to separation in a) is taken. In some embodiments, in (b), at least a part of the stream com-prising methanol MR(i) obtained in (a), preferably the stream comprising methanol MR(i) obtained in (a), is fed to a different reactive distillation column K(i) as that from which the bottoms stream P(i) comprising alkali metal methoxide A(i)OMe and methanol, subjected to separation in a), is taken. Whether MR(i) is free of alkali metal methoxide or does comprise a certain amount thereof depends, as the alkali metal methoxides themselves have no vapor pressure, on droplet entrainment. If and / or how much droplet entrain- ment occurs depends on the process design, e.g. whether droplet separators are included, and the operating mode of the separation unit. The amount of alkali metal methoxide in MR(i) can be determined by conventional means known to the skilled person. As indicated above, the stream comprising methanol MR(i) obtained in (a) is preferably fed to the same reactive distillation column K(i) from which the bottoms stream P(i) comprising alkali metal methoxide A(i)OMe and methanol, subjected to separation in (a) is taken. This set-up is favorable as detrimental cross-contami- nation can be avoided.In some preferred embodiments of the integrated process, feeding at least a part of the stream comprising methanolMR(i) obtained in (a) in (b) is done into the upper part, preferably the top, of the at least one, preferably same, reac- tive distillation column K(i).In some preferred embodiments of the integrated process, (b) comprises(b.1) splitting the stream comprising methanol MR(i) obtained in (a), optionally the stream MR(i) in liquid form, into atleast two sub-streams MR(ia) and MR(ib);(b.2) feeding sub-stream MR(ia) into at least one reactive, preferably the same, distillation column K(i);(b.3) feeding sub-stream MR(ib) into the same reactive distillation column K(i) as sub-stream MR(ia) but at a differ-ent position than sub-stream MR(ia), preferably at a position in the upper part, preferably at the top, of thesame reactive distillation column K(i). In some embodiments, feeding sub-stream MR(ia) according to (b.2) is done into the lower part of at least one reac- tive, preferably the same, distillation column K(i).In some embodiments, the top of at least one, more preferably of each reactive distillation column K(i) is equippedwith a droplet separating device DSD(i), more preferably a demister, said demister of the same reactive distillation column K(i) more preferably comprising an inlet means for feeding a stream MR(i) or MR(ib) comprising methanol into said demister. Preferably, enough of MR(i) is feed to said demister of the same reactive distillation column K(i) to en-sure a complete rinsing thereof, i.e. MR(ib) is preferably dimensioned so that a complete rinsing of the demister isensured. Splitting of the stream comprising methanol MR(i) obtained in (a) into at least two sub-streams MR(ia) andMR(ib) is preferably only done if a stream MR(i) is more than what is required to ensure a complete rinsing of the de-mister. In some preferred embodiments of the integrated process, the ratio of the mass flow rate of sub-stream MR(ia)to the mass flow rate of sub-stream MR(ib) is in the range of from 1:10 to 10:1, preferably in the range of from 0.2:1 to0.95:1, more preferably in the range of from 0.3:1 to 0.9:1¸ more preferably in the range of from 0.4:1 to 0.8:1 more preferably in the range of from 0.5:1 to 0.6:1. Generally, a stream M comprising methanol is fed into the rectification column D. This stream 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 suitable 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 preferably 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 preferably 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. Preferably, the stream Mis fed to the upper part of D, more preferably at least 2, 3 or 4 theoretical stages from the top of D, more preferably atleast 4 theoretical stages from the top of D, more preferably between the 4thand the 20ththeoretical stage from the top of D, more preferably between 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 14ththeoret- ical stage or between to 12thand the 15ththeoretical stage. As far as the temperature of the stream M is concerned atwhich the stream M is fed into D, it is preferred that the temperature is in the range of from ambient temperature upto the boiling point of methanol at the column pressure of D; more preferably the temperature is ambient tempera- ture. In some preferred embodiments of the integrated process, the n reactive columns K(i) have each a reboiler, prefera-bly bottom reboiler, VK(i). Preferably, at least parts of the bottom streams P(i) from the reactive columns K(i) arepassed through the respective bottom reboilers VK(i). Said at least parts of the streams P(i) are, after passagethrough the bottom reboilers VK(i), at least partially returned into K(i), wherein the returned parts of one or more streams P(i) preferably have, due to the passage through the one or more bottom reboilers VK(i) a higher tempera- ture compared to the bottoms streams P(i) before passage through the bottom reboilers VK(i). Preferably, the parts ofthe bottom streams P(i), which are passed through the bottom reboilers VK(i) are different from the part of at leastone of the n bottoms streams P(i), which is subjected in the separation unit SU to a solid separation. n = 2In some preferred embodiments of the integrated process, n is 2. In these embodiments, preferably a stream H(1)comprises dissolved sodium hydroxide and a stream H(2) comprises dissolved potassium hydroxide, wherein sodium methoxide is prepared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassiummethoxide is prepared in the reactive distillation column K(2) from which the stream W(2) is obtained. Preferably, thepart of the bottoms streams P(1) from reactive distillation column K(1) comprising sodium methoxide NaOMe andmethanol is subjected in the separation unit SU(1) to the solid separation in (a), obtaining a residue enriched in Na-OMe compared to P(1), preferably containing solid sodium methoxide NaOMe, and a stream MR(1) comprising meth-anol; and in (b), at least a part of the stream comprising methanol MR(1) obtained in (a) is fed to the reactive distilla-tion column K(1).In some embodiments, a part of the bottoms streams P(2) from reactive distillation column K(2) comprising potas-sium methoxide KOMe and methanol is subjected in a separation unit SU(2) to the solid separation in (a), obtaining aresidue enriched in KOMe compared to P(2), preferably containing solid potassium methoxide KOMe, and a stream MR(2) comprising methanol; and in (b), at least a part of the stream comprising methanol MR(2) obtained in (a) is fed to the reactive distillation column K(2).In some further embodiments, the part of the bottoms streams P(1) from reactive distillation column K(1) comprisingsodium methoxide NaOMe and methanol is subjected in a first separation unit SU(1) to the solid separation in (a), obtaining a residue enriched in NaOMe compared to P(1), preferably containing solid sodium methoxide NaOMe, and a stream MR(1) comprising methanol; and in (b), at least a part of the stream comprising methanol MR(1) ob- tained in (a) is fed to the reactive distillation column K(1) and the part of the bottoms streams P(2) from reactive distil-lation column K(2) comprising potassium methoxide KOMe and methanol is subjected in a second separation unitSU(2) to the solid separation in (a), obtaining a residue enriched in KOMe compared to P(2), preferably containing solid potassium methoxide KOMe, and a stream MR(2) comprising methanol; and in (b), at least a part of the streamcomprising methanol MR(2) obtained in (a) is fed to the reactive distillation column K(2).The separation unit SU(1) and / or the separation unit SU(2) is / are preferably an evaporation unit or a partial evapora-tion unit as described above. In some embodiments, the separation unit SU(1) and / or SU(2) (each) comprise(s) atleast a paddle dryer. In some preferred embodiments of the integrated process, feeding at least a part of the stream comprising methanol MR(1) obtained in (a) is done in (b) into the upper part, preferably the top, of the at least one,preferably same, reactive distillation column K(1) and / or feeding at least a part of the stream comprising methanolMR(2) obtained in (a) in (b) is done into the upper part, preferably the top, of the at least one, preferably same, reac-tive distillation column K(2). As indicated above, the n reactive columns K(i) have each a reboiler, preferably bottomreboiler, VK(i). Preferably, K(1) has a reboiler, preferably bottom reboiler, VK(1) and K(2) has a reboiler, preferablybottom reboiler, VK(2). Preferably, at least a part of the bottom stream P(1) from the reactive columns K(1) and at least a part of the bottom stream P(2) from the reactive columns K(2) are passed through the respective bottom re- boiler VK(1), VK(2). Said at least parts of the streams P(1), P(2) are, after passage through the bottom reboilers VK(1), VK(2), at least partially returned into K(1), K(2), wherein the returned parts of the streams P(1), P(2) preferably have, due to the passage through the bottom reboilers VK(1),VK(2) a higher temperature compared to the bottoms streams P(1), P(2) before passage through the bottom reboilers VK(1),VK(2). Preferably, the parts of the bottom streams P(1),P(2) which are passed through the bottom reboilers VK(1),VK(2)are different from the part of the bottoms streams P(1)and / or P(2), which is / are subjected in the separation unit SU(1) and / or SU(2) to a solid separation.In some preferred embodiments of the integrated process, (b) comprises(b.1) splitting the stream comprising methanol MR(1) obtained in (a), optionally MR(1) in liquid form, into at least twosub-streams MR(1a) and MR(1b);(b.2) feeding subs-stream MR(1a) into reactive distillation column K(1);(b.3) feeding subs-stream MR(1b) into reactive distillation column K(1) at a different position than MR(1a), preferablyat a position in the upper part, preferably at the top, of the same reactive distillation column K(1). In some embodiments, feeding sub-stream MR(ia) according to (b.2) is done into the lower part of reactive distillation column K(1). The same applies as disclosed above generally regarding MR(i), MR(ia), MR(ib) as well as that in some embodi- ments, the top of the reactive distillation column K(1) is equipped with a droplet separating device DSD(1), more pref- erably a demister, said demister more preferably comprising an inlet means for feeding a stream MR(1) or MR(1b) comprising methanol into said demister. Preferably, enough of MR(1) is feed to said demister of the same reactivedistillation column K(1) to ensure a complete rinsing thereof, i.e. MR(1b) is preferably dimensioned so that a completerinsing of the demister is ensured. Furthermore, it applies for MR(1) that splitting of the stream comprising methanolMR(1) obtained in (a) into at least two sub-streams MR(1a) and MR(1b) is preferably only done if the stream MR(1) ismore than what is required to ensure a complete rinsing of the respective demister; for further details, the same ap- plies as indicated above.The same applies for MR(2), when a part of the bottoms streams P(2) from reactive distillation column K(2) compris-ing potassium methoxide KOMe and methanol is subjected in a separation unit SU(2) to the solid separation in (a),obtaining a residue enriched in KOMe compared to P(2), preferably containing solid potassium methoxide KOMe,and a stream MR(2) comprising methanol, i.e. for MR(2), (b.1), (b.2) and (b.3). What is described above regardingdroplet separating device, demister and splitting of stream MR(2) applies equally.In some preferred embodiments, the integrated process further comprises(c) obtaining a vapor phase V comprising methanol at the top of the rectification column D, said vapor phase Vhaving a pressure pV and a temperature TV;(d) preparing at least two streams from the vapor phase V, comprising a vapor stream G having a pressure pGand a temperature TGwith 0.95 ≤ pG / pV≤ 1.00, and further comprising a vapor stream T(1), said vapor stream T(1) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pV;(e) passing at least a part of the stream T(1) as a heating medium through a reboiler V(1) of the rectification col-umn D, preferably through an intermediate reboiler V(1a) of the rectification column, obtaining a, preferably at least partially condensed, stream TC(1) having a temperature TTc(1a) with TTc(1a) < TT(1a);(f) feeding at least a part of the stream TC(1) into the rectification column D.In some preferred embodiments, the integrated process further comprises(g) preparing the n streams G(i) from the vapor stream G, each of the streams G(i) having a pressure pG(i) and atemperature 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). In some preferred embodiments, the process further comprises for at least one reactive distillation column K(i), pref- erably for n reactive distillation columns K(i), feeding the stream G(i) into the lower part of the reactive distillation col- umn K(i) and feeding the aqueous liquid stream H(i) into the upper part of the reactive distillation column K(i). With respect to the stream G, it is preferred that said stream G comprises methanol and water, wherein more prefer- ably from 99.95 to 100 weight-% of G consist of methanol and water, and wherein 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 pre- pared from the vapor stream G, each of the streams G(i) having a pressure pG(i) and a temperature TG(i) with pG(i) > pG and TG(i) > TG for each stream G(i), and feeding each stream G(i) into the respective reactive distillation column K(i), wherein for preparing the n streams G(i), at least one compression unit CG is employed. As indicated above, in some preferred embodiments of the integrated process, a stream H(1) comprises dissolved sodium hydroxide and a stream H(2) comprises dissolved potassium hydroxide, wherein sodium methoxide is pre-pared in the reactive distillation column K(1) from which the stream W(1) is obtained and potassium methoxide is pre-pared in the reactive distillation column K(2) from which the stream W(2) is obtained. In some preferred embodiments of the process n is 2 (n = 2). Preferably, the stream G is divided into the two streams G(1) and G(2), wherein the stream G has 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 divided by any conceivable method. Preferably (c) comprises passing the stream G into a stream dividing device S, said device more preferably compris- ing a pipe junction. In context, it is noted that the term “the stream is divided into two streams” refers to a method ac- cording to which the streams obtained from said dividing have the same chemical composition as the stream G. Asfar as the ratios f(G(1)) / f(G) and f(G(2)) / f(G) are concerned, the present invention allows for a flexible adjusting ofsaid 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 relative to the desired amount of A(2)OMe, preferably potas-sium methoxide, to be obtained.As indicated above, for preparing the n streams G(i), preferably at least one compression unit CG is employed. Thestream G can be passed through the at least one compression unit CG, thereby realizing a pressure increase of G. Preferably, the pressure is suitably increased so that the pressure of the streams after dividing is adapted to the de- sired 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, preferably wherein n is 2, it is preferred that the dividing according to (c) comprises passing the compressed stream G into a stream dividing device S, said device preferably comprising a pipe junction and at least one control device allowing 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 thestream G(2) or in both streams G(1) and G(2), and it is preferred that the at least one control device preferably is acontrol valve. Afterwards, the compressed stream G is fed into the dividing device S and subsequently, the resulting streams G(1) and G(2) are fed into the reactive distillation columns K(1) and K(2) respectively. Alternatively, the pres- sure increase mentioned above is realized not by compressing the stream G prior to, but after dividing. In this alter- native 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 0.6bar, more preferably in the 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 distillation column K(2), the stream G(2) is passed through a compres- sor CG(2), thereby realizing a pressure 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 preferred 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 preferably 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 reactive 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, 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 theo- retical stages. Generally, the stream G(1) can be fed at any suitable position into K(1); preferably, G(1) is fed into thereactive distillation column K(1) at a position between the bottoms and the 5th theoretical stage, more preferably be-tween the bottoms 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 inthe range of from 1 to 5 bar(abs). Suitable preferred ranges are, for example, from 1 to 3 bar(abs) or from 2 to 4bar(abs) of from 3 to 5 bar(abs). While it is generally possible to operate the reactive distillation column K(1) with re- flux, 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 100weight-%, 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 preferably 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 prefer- ably, 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 include, for example, 750 weight-ppm or 500 weight-ppm or 250 weight-ppm; water content is determined based on a Karl-Fischer-titration and calculatedbased on the titration result. Water is predominantly present in the mixture P(1) as A(1)OHaq, i.e. the mixture P(1)optionally comprises residual amounts of A(1)OH. Preferably, the concentration 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.As indicated above, in some embodiments, the top of at least one, more preferably of each reactive distillation col-umn K(i) is equipped with a droplet separating device DSD(i), more preferably a demister, said demister of the same reactive distillation column K(i) more preferably comprising an inlet means for feeding a stream MR(ib) comprising methanol into said demister. Preferably, enough of MR(i) is feed to said demister of the same reactive distillation col- umn K(i) to ensure a complete rinsing thereof, i.e. MR(ib) is preferably dimensioned so that a complete rinsing of thedemister is ensured. The ratio of the mass flow rate of sub-stream MR(ia) to the mass flow rate of sub-stream MR(ib)is as indicated above. According to the present invention, it is preferred that the top of the reactive distillation column K(1) is equipped with a suitable droplet separating device DSD(1), preferably a demister. Thus, the process prefera- bly comprises separating droplets comprising A(1)OH, preferably sodium hydroxide, from the vapor stream in the topof K(1). Regarding the ratio of the mass flow rate of sub-stream MR(1a) to the mass flow rate of sub-stream MR(1b),reference is made to the description above with respect to the streams MR(ia) and MR(ib).As far as the stream H(2) is concerned, 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 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 exchanger. It is preferred that the stream H(2) is fed into the top of the reactive distil- lation 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 10to 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 theo- retical 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 be- tween the bottoms 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 preferred 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 re- flux, it is preferred that the reactive distillation column K(2) is operated at a reflux ratio of 0:1. As indicated above, in some embodiments, the top of at least one, more preferably of each reactive distillation col- umn K(i) is equipped with a droplet separating device DSD(i), more preferably a demister, said demister of the same reactive distillation column K(i) more preferably comprising an inlet means for feeding a stream MR(ib) comprising methanol into said demister. Preferably, enough of MR(i) is feed to said demister of the same reactive distillation col- umn K(i) to ensure a complete rinsing thereof, i.e. MR(ib) is preferably dimensioned so that a complete rinsing of thedemister is ensured. The ratio of the mass flow rate of sub-stream MR(ia) to the mass flow rate of sub-stream MR(ib)is as indicated above. According to the present invention, it is preferred in some embodiments that the top of the re- active distillation column K(2) is equipped with a suitable droplet separating device DSD(2), preferably a demister. Thus, the process preferably comprises separating droplets comprising A(2)OH, preferably potassium hydroxide,from the vapor stream in the top of K(2). Regarding the ratio of the mass flow rate of sub-stream MR(2a) to the massflow rate of sub-stream MR(2b), reference is made to the description above with respect to the streams MR(ia) and MR(ib). 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 preferably 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 potas- sium 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; water content is determined based on a Karl-Fischer-titration and calculated based on the titration result. Water is predominantly present in the mixture P(2) as A(2)OHaq, i.e. the mix- ture P(2) optionally comprises residual amounts of A(2)OH. Preferably, the concentration of A(2)OMe, preferably po- tassium 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 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 compressor C(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 rectification column D, the stream W(2) is passed through a compressor C(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 embodiment of the present in- vention, it is also possible to suitably combine the streams W(1) and W(2), prior to being passed through a compres- sor, 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 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. 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 simultaneously preparing, inaddition to the 2 mixtures P(1) and P(2) as described above in detail, a 3rd mixture P(3) etc. can be obtained, theskilled person, based on his general knowledge, will be 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 conceiva- ble 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 crystalline sodium methoxide and solid, preferably crystalline potassium methoxide, can be obtained. Recycling of W(i) into D In some preferred embodiments, the integrated process further comprises(h) feeding at least a part of one or more of the top streams W(i) into the rectificationcolumn D.- Concept AGenerally, it is preferred according to the integrated process of the present invention that at least a part of one or more of the top streams W(i) is fed into rectification column D (feature (h)). In some preferred embodiments of the process, feeding of the stream W(i) into the rectification column D according to (h) comprises feeding at least a first stream W(1) and a second stream W(2) at least partially into the rectification column D, wherein (h) preferably comprises(h.1) feeding at least a part of the stream W(1) into the lower part of the rectificationcolumn D at a position I(1);(h.2) feeding at least a part of the 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); wherein between the positions I(1) and I(2), the rectification column D is equipped with internals.Preferably, below the position I(2) the rectification column D is equipped with internals.The rectification column D’s internals are selected from tray, unstructured (random) packing, structured packing and mixtures of two or more thereof. Preferably, rectification column D comprises one or more internals, preferably se- lected from the group consisting of tray, unstructured (random) packing, structured packing and mixtures of two or more thereof. A tray is preferably selected from the group consisting of bubble tray, sieve tray, valve tray, tunnel tray, slot tray and mixtures of two or more thereof. An unstructured packing is preferably selected from the group consist- ing of Raschig rings, Pall rings, Berl saddles, lntalox saddles and mixtures of two or more thereof. Structured pack- ings are sold, for example, 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 unstruc- tured packings are contained in the rectification column, these can be divided or there can be one continuous pack- ing. Positon I(2) is preferably located in the lower third of rectification column D and positon I(1) is also located in the lower third of rectification column D, wherein 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 concentration 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) with0.95 ≤ cMeOH(1) / cMeOH(D1) ≤ 1.05. W(2) is preferably fed into rectification column D at a position I(2), wherein theMeOH concentration 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 of the process, stream W(1) comprises methanol and water at a molar methanol-to- water ratio r(1) and wherein the stream W(2) comprises methanol and water at a molar methanol-to-water ratio r(2) with r(2) < r(1). Preferably, the process comprises(i) feeding a stream M comprising methanol into the rectification column D at a position I(M);wherein the positions I(1) and I(2) are located below the position I(M).- Concept BCDGenerally, as indicated above, it is preferred according to the integrated process of the present invention that at leasta part of one or more of the top streams W(i) is fed into rectification column D. In some preferred embodiments, (h)comprises(h.1’) feeding at least a part of the top stream W(1) into the lower part of the rectification column D at a position I(1);(h.2’) at least partially condensing at least a part of the top stream W(2), obtaining an at least partially condensedstream WC(2), and feeding at least a part of the stream WC(2) into the rectification column at a position I(2).In some preferred embodiments, the integrated process further comprises(i) feeding a stream M comprising methanol into the rectification column D at a position I(M).Feeding of the stream M into the rectification column D according to (i) is preferably done as explained in more detailherein. ^Alternative(s) BAs indicated above, at least a part of a second vapor stream W(2) is at least partially condensed in (h.2’), thereby obtaining an at least partially condensed stream WC(2), and at least a part of the stream WC(2) is fed into the rectifi- cation column at a position I(2). Here regarding the alternative B and herein below also regarding alternatives C, D,“at least partially condensed” regarding vapor stream W(2) means that at least 2 weight-% of stream W(2) are con-densed and form Wc(2). Furthermore, in (i) a stream M comprising methanol is fed into the rectification column D at a position I(M); wherein (h.2’) comprises passing the top stream W(2) having a temperature TW(2)through at least one heat exchanger E, obtaining an at least partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2), and feeding at least a part of the at least partially condensed stream WC(2) into the rectification column D at the position I(2); and wherein (i) comprises passing the stream M having a temperature TM1through one or more of said at least one of heat exchangers E, obtaining a stream M having a temperature TM2with TM2> TM1, and feeding the stream M having the temperature TM2into the rectification column D at the position I(M). Preferably, at least partially condensing at least a part of the top stream W(2), obtaining an at least partially con-densed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification column at a position I(2)comprises passing the top stream W(2) having a temperature TW(2) through a heat exchanger E(1a), obtaining a par- tially condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2); feeding at least a part of the at least partially condensed stream WC(2) into the rectification column D at the position I(2).In these preferred embodiments (h.2’) preferably comprises(h.2’.1) passing the vapor stream W(2) having a temperature TW(2) through at least one heat exchanger E, ob-taining an at least partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2), and(h.2’.2) feeding at least a part of the at least partially condensed stream WC(2) into the rectification column D atthe position I(2). In some preferred embodiments, at least partially condensing at least a part of the top stream W(2), obtaining an atleast partially condensed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification columnat a position I(2) comprises passing the top stream W(2) having a temperature TW(2) through a heat exchanger E(1a),obtaining a partially condensed stream WC1(2) having a temperature TWC1(2) with TWC1(2) < TW(2); passing the stream WC(2) having the temperature TWC1(2) through a heat exchanger E(1b), obtaining a stream WC2(2) having a tempera- ture TWC2(2) with TWC2(2) < TWC1(2); feeding at least a part of the stream WC2(2) into the rectification column D at the po- sition I(3). Preferably, I(M) is above I(2) and I(2) is above I(1).In these preferred embodiments, (i) comprises(i.1) passing the stream M having a temperature TM1 through one or more of said at least one of heat exchangersE, obtaining a stream M having a temperature TM2with TM2> TM1, and(i.2) feeding the stream M having the temperature TM2 into the upper part of the rectification column D at the posi-tion I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1).In some preferred embodiment of the integrated process, (h.2’) comprises(h.2’.1’) passing the vapor stream W(2) having a temperature TW(2) through a heat exchanger E(1a), obtaining apartially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2);(h.2’.2’) feeding at least a part of the at least partially condensed stream WC(2) into the lower part of the rectifica-tion column D at the position I(2); and (i) comprises(i.1’) passing the stream M having the temperature TM1 through the heat exchanger E(1a), obtaining the streamM having the temperature TM2;(i.2’) feeding the stream M having the temperature TM2 into the upper part of the rectification column D at theposition I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1).In these preferred embodiments, (h.2’) comprises(h.2’.1’’) passing the vapor stream W(2) having a temperature TW(2) through a heat exchanger E(1a), obtaining apartially condensed stream WC1(2) having a temperature TWC1(2)with TWC1(2)< TW(2);(h.2’.2’’) passing the stream WC1(2) having the temperature TWC1(2) through a heat exchanger E(1b), obtaining a,preferably completely condensed, stream WC2(2) having a temperature TWC2(2)with TWC2(2)< TWC1(2);(h.2’.3’’) feeding at least a part of the stream WC2(2) into the lower part of the rectification column D at the posi-tion I(2); and (i) comprises(i.1’’) passing the stream M having the temperature TM1 through the heat exchanger E(1a), obtaining the stream Mhaving the temperature TM2;(i.2’’) feeding at least a part of the stream M having the temperature TM2 into the upper part of the rectification col-umn D at the position I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the MeOH concentration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2). W(1) is fed into rectification column D at a position I(1), wherein the MeOH concen-tration 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. At least partially condensed stream WC(2) has a methanol concentration cMeOH(2’) equal to the methanol concentra- tion in W(2) and lower than the methanol concentration in W(1). WC(2) is preferably fed into rectification column D at a position I(2), wherein the MeOH concentration 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 amost efficient processing of rectification column D. The same applies with respect to WC2(2). Heat emitted fromstream WC1(2) in heat exchanger E(1b) is taken up by a cooling medium such as water or ambient air. I(M) is in the upper half of rectification column D, preferably in its upper third. Preferably, there is at least one, more preferably there are at least 2, theoretical stages between I(M) and the head of the rectification column D. I(2), which is above I(1), and I(1) are both in the lower half of rectification column D, preferably both in its lower third, wherein more preferably I(2) is preferably at least one, more preferably at least 5, theoretical stages above I(1). ^Alternative CIn some preferred embodiments of the integrated process,(h) and (i) comprise passing the vapor stream W(2) having a temperature TW(2) through at least one heat exchanger E(2), obtaining an at least partially, preferably essentiallycompletely, condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2); and admixing the stream M,prior to feeding it into the rectification column D at the position I(M), with at least a part of the stream WC(2), wherein I(M) = I(2), wherein preferably, I(M) is above I(1). The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the MeOH concentration in W(2) cMeOH(2) with cMeOH(1) > cMeOH(2). W(1) is fed into rectification column D at a position I(1), wherein the MeOH concen- tration 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. At least partially condensed stream WC(2) has a methanol concentration cMeOH(2’) equal to the methanol concentra-tion in W(2) and lower than the methanol concentration in W(1). The mixture of WC(2) and M having a methanol con-centration cMeOH(mixture) is preferably fed into rectification column D at a position I(M) , wherein the MeOH concen- tration at that position I(M) within the rectification column D cMeOH(DM) is preferably about equal to cMeOH(mixture) with 0.95 ≤ cMeOH(mixture) / cMeOH(D2) ≤ 1.05. This preferred feeding manner enables a most efficient processing of rectifi- cation column D. Heat emitted from stream W(2) in heat exchanger E(2) is taken up by a cooling medium such as water or ambient air. I(M), where the mixture of stream M and at least a part of the stream WC(2) is fed into the rectification column D is in its lower half. Preferably, there is at least one, more preferably there are at least 2, theoretical stages between I(1) and I(M). I(1) is in the lower half of rectification column D, preferably in its lower third. ^Alternative DIn some preferred embodiments of the integrated process, (h) and (i) comprise admixing the vapor stream W(2) hav-ing a temperature TW(2) with the stream M having a temperature TM1 with TW(2) > TM1, thereby at least partially con- densing the stream W(2), and feeding the stream obtained from mixing into the rectification column D at the position I(M), wherein I(M) = I(2), wherein preferably, I(M) is above I(1).The methanol concentration in stream W(1) cMeOH(1) is preferably higher than the MeOH concentration in W(2)cMeOH(2) with cMeOH(1) > cMeOH(2). W(1) is fed into rectification column D at a position I(1), wherein the MeOH concen- tration 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. The mixture of W(2) and M having a methanol concentration cMeOH(mixture) is preferably fed into rectification columnD at a position I(M) , wherein the MeOH concentration at that position I(M) within the rectification column DcMeOH(DM) is preferably about equal to cMeOH(mixture) with 0.95 ≤ cMeOH(mixture) / cMeOH(DM) ≤ 1.05. This preferred feeding manner enables a most efficient processing of rectification column D. I(M), where the mixture of stream M and stream W(2) is fed into the rectification column D is in its lower half. Prefera- bly, there is at least one, more preferably there are at least 2, theoretical stages between I(1) and I(M). I(1) is in the lower half of rectification column D, preferably in its lower third.In some preferred embodiments, the integrated process is an integrated process for simultaneously preparing twomixtures P(1) and P(2), P(1) comprising sodium methoxide and methanol and P(2) comprising potassium methoxideand methanol, and for preparing solid sodium methoxide and solid potassium methoxide, wherein the process com-prises providing 2 reactive distillation columns K(1) and K(2); providing 2 aqueous liquid streams H(1) and H(2), H(1) comprising dissolved sodium hydroxide and H(2) comprising dissolved potassium hydroxide; and providing a rectification column D;wherein the process comprises preparing the two metal methoxides in the two reactive distillation column K(1), K(2)under reactive distillation conditions from the 2 streams H(1) and H(2) and 2 streams G(1), G(2) comprising metha- nol, thereby obtaining 2 top streams W(1), W(2) comprising methanol and water; and obtaining 2 bottoms streams P(1), P(2), P(1) comprising sodium methoxide NaOMe and methanol and P(2) comprising potassium methoxide KOMe and methanol; the integrated process further comprising(a) subjecting at least a part of at least one of the 2 bottoms streams P(1), P(2) comprising the respective al-kali metal methoxide and methanol in a separation unit SU to a solid separation, obtaining a residue en-riched in the respective alkali metal methoxide compared to the respective P(1) or (P(2), preferably con- taining the respective alkali metal methoxide in solid form, and a stream MR(1) or MR(2) comprising metha- nol;(b) feeding at least a part of the stream comprising methanol MR(1) or MR(2)obtained in (a) to at least one re-active distillation column K(1) or K(2) and / or feeding at least a part of the stream comprising methanol MR(1) or MR(2) obtained in (a) to rectification column D;(c) obtaining a vapor phase V comprising methanol at the top of the rectification column D, said vapor phaseV having a pressure pV and a temperature TV;(d) preparing at least two streams from the vapor phase V, comprising a vapor stream G having a pressure pGand a temperature TGwith 0.95 ≤ pG / pV≤ 1.00, and further comprising a vapor stream T(1), said vapor stream T(1) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pV;(e) passing at least a part of the stream T(1) as a heating medium through a reboiler V(1) of the rectificationcolumn D, preferably through an intermediate reboiler V(1a) of the rectification column, obtaining a, prefer- ably at least partially condensed, stream TC(1) having a temperature TTc(1a) with TTc(1a) < TT(1a);(f) feeding at least a part of the stream TC(1) into the rectification column D;(g) preparing the 2 streams G(1), G(2) from the vapor stream G, each of the streams G(1), G(2) having apressure pG(1 or 2) and a temperature TG(1 or 2) with pG(1 or 2) > pG for each stream G(1), G(2); and feeding each stream G(1), G(2) into the respective reactive distillation column K(1), K(2); and(h)+(i) admixing the vapor stream W(2) having a temperature TW(2) with a stream M comprising methanol having atemperature TM1 with TW(2) > TM1, thereby at least partially condensing the stream W(2), and feeding the stream obtained from mixing into the rectification column D at the position I(M), wherein I(M) = I(2), wherein preferably, I(M) is above I(1). Details, embodiments and preferred embodiments of the steps (a) to (h) + (i) are as defined above. Preferably, the stream MR(1) is fed to the to the reactive distillation column K(1) as a liquid stream or the streamMR(2) is fed to the reactive distillation column K(2) as a liquid stream.Preferably, the stream MR(1) comprising methanol obtained in a) is subjected to condensation, thereby obtainingMR(1) in liquid form, or the stream MR(2) comprising methanol obtained in a) is subjected to condensation, therebyobtaining MR(2) in liquid form; wherein condensation is done is preferably done in an apparatus operated with a cool- ing medium, wherein condensation is more preferably complete. Rectification column D with top vapor recompression In some preferred embodiments of the integrated process, rectification column D is operated with top vapor recom- pression, wherein preferably realizing a 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. Preferably, the waste gas stream T(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). With compression unit(s)- With a first compression unit CT(1)In some preferred embodiments of the integrated process, (e) comprises passing stream T(1) through a first com-pression unit CT(1), obtaining a compressed stream T(1a), and passing the compressed stream T(1a) through a re- boiler V(1), preferably an intermediate reboiler V(1a) of rectification column D, obtaining a condensed stream Tc(1a).Preferably, Tc(1a), at least partially, is fed to a first condensate drum CD(1), wherein from said first condensate drumCD(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 depressurized form, ob- taining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. In some preferred embodiments of the process, a stream T(Di) having a temperature TT(Di)is taken from the rectifica- tion column D at an intermediate position and passed for heating purpose through the intermediate reboiler V(1a) of the rectification column 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. Heated stream Th(Di) preferably comprises two phases, i.e. a gaseous and a liquid part.- With first and second compression units CT(1), CT(2)In some preferred embodiments of the integrated process, (e) comprises(e.1) splitting vapor stream T(1) into at least two streams; passing a first part stream of T(1) through the first com-pression unit CT(1), obtaining a compressed stream T(1a), and passing a second part stream of T(1) through a second compression unit CT(2), obtaining a compressed stream T(1b);(e.2) passing the compressed stream T(1a) through an intermediate reboiler V(1a) of rectification column D, obtain-ing a condensed stream Tc(1a), and passing the compressed stream T(1b) through a bottoms reboiler V(1b) of rectification column D, obtaining a condensed stream Tc(1b).The ratio of the heat flow rate of T(1a) to the heat flow rate of T(1b) f((T1a)) / f(T(1b)) is in the range of from 0 to 12,preferably in the range of from 2 to 8, more preferably in the range of from 3 to 6. In some preferred embodiments of the process, a stream T(Di) having a temperature TT(Di) is taken from the rectifica- tion column D at an intermediate position and passed for heating purpose through the intermediate reboiler V(1a) of the rectification column 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; and a stream T(Db) having a temperature TT(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 column D, obtaining a stream Th(Db) havinga temperature TTh(Db) with TTh(Db) > TT(Db), wherein heated stream Th(Db) is reintroduced into rectification column D. Heated stream Th(Di) preferably comprises two phases, i.e. a gaseous and a liquid part. Analogously, heated streamTh(Db) preferably comprises two phases, i.e. a gaseous and a liquid part.Preferably, Tc(1a) and / or Tc(1b), preferably Tc(1a) and Tc(1b), each at least partially, is / are fed to a first condensatedrum CD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are re-moved, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combined with theliquid streams T(2l) and (T2gl) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification column D. 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 3 showing a process according to the present invention with reflux. When the rectification column is operated with top vapor recompression, it is alsopreferred that realizing the reflux ratio comprises using 2 condensers, V(2) and V(3), as described below in that(i) in addition to the at least three streams G, T(1a) and / or T(1b), which are prepared from the vapor phase 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 con- denser 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 a second condensate drum CD(2) in depressurized form;(ii) feeding Tc(1a) and / or Tc(1b), each at least partially, to the 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 stream 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 from said second condensate drum CD(2) 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 pcsabout equal to the pressure at the top of rectification column D as described above, i.e.0.95 ≤ pcs / ptD≤ 1.05. With a third compression unit CT(3) In some preferred embodiments of the integrated process, a providing a third compression unit CT(3) is provided, wherein (e) comprises preparing at least four streams from the vapor phase V, said at least four streams comprising vapor stream G, stream T(1a), stream T(1b), and a further stream T(1c), said stream T(1c) having a pressure pT(1c) and a temperature TT(1c) with pT(1c) > pV and TT(1c) > TV, wherein for preparing the stream T(1c), the third compression unit CT(3) is employed. In some preferred embodiments, preparing the at least four streams according to (e) comprises splitting the vapor phase V into at least two vapor streams comprising the stream 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; and preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1). Said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises in some preferred embodiments a splitting of T(1) into at least two streams; passing a first part stream of T(1) through CT(1), obtaining T(1a), and passing a second part stream of T(1) through the second com- pression unit CT(2), obtaining T(1b), and splitting T(1a) into at least two streams and passing a part stream of T(1a) through the third compression unit CT(3), obtaining T(1c). In some alternatively preferred embodiments, said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises splitting T(1) into at least two streams; passing a first part stream of T(1) through CT(1), obtaining T(1a), and passing a second part stream of T(1) through the third compression unit CT(3), obtaining T(1c); and splitting T(1a) into at least two streams and passing a part stream of T(1a) through the second compres- sion unit CT(2), obtaining T(1b). In some other alternative preferred embodiments, said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises splitting vapor stream T(1) into at least three streams; passing a first part stream of T(1) through the first compression unit CT(1), obtaining T(1a), passing a sec- ond part stream of T(1) through the second compression unit CT(2), obtaining T(1b), and passing a third part stream of T(1) through the third compression unit CT(3), obtaining T(1c). In some other alternative preferred embodiments,said preparing at least the three streams T(1a), T(1b) and T(1c) from the vapor stream T(1) comprises passing T(1)through the first compression unit CT(1), obtaining T(1a); splitting T(1a) into at least three part streams, passing a part stream of T(1a) through the second compression unit CT(2), obtaining T(1b), and passing a part stream of T(1a) through the third compression unit CT(3), obtaining T(1c). In some preferred embodiments of the integrated process, the n reactive columns K(i) have each a reboiler, prefera- bly bottom reboiler, VK(i) and at least a part of T(1c) is passed as heating medium through at least one bottom re- boiler VK(i) of one of the n reactive distillation column K(i), obtaining a stream TC(1c) having a temperature TTc(1c) with TTc(1c)< TT(1c).In some preferred embodiments, at least a first part of T(1c) (T(1c.1) is passed to a bottom reboiler VK(1) of a reac- tive distillation column K(1) and a second part of T(1c) (T(1c.2)) is passed to a bottom reboiler VK(2) of a reactive dis-tillation column K(2). Passing at least a part of stream T(1c) as a heating medium through all bottom reboilers VK(i),enables a process wherein no heating medium especially no hot water steam, from other sources is required for op- erating D and K(i), since all thermal energy needed is generated by the process itself. Only input of compression en- ergy (electrical energy) is required. When green electricity is used, the integrated process for simultaneously prepar- ing n mixtures P(i) comprising alkali metal methoxide and methanol can thus be carried out CO2-neutral. In some pre- ferred embodiments with two reactive distillation columns K(1), K(2), at least a first part of T(1c) (T(1c.1) is passed toa bottom reboiler VK(1) of a reactive distillation column K(1) and a second part of T(1c) (T(1c.2)) is passed to a bot-tom reboiler VK(2) of a reactive distillation column K(2). Preferably, from VK(1) a stream TC(1c.1) and from VK(2) astream TC(1c.2) is / are obtained, which are then, either separately or at least partially combined as TC(1c), fed into thesame (first) condensate drum CD(1), into which also Tc(1a) and / or Tc(1b) are fed. 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 overviews in Figure 3 showing a process accord- ing to the present invention with reflux. When the rectification column is operated with top vapor recompression, it isalso preferred that realizing the reflux ratio comprises using 2 condensers, V(2) and V(3), as described below in that(i) in addition to the at least three streams G, T(1a) and T(1b), which are prepared from the vapor phase V, pre-paring 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 con- denser 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 a second condensate drum CD(2) in depressurized form;(ii) feeding TC(1c), preferably with Tc(1a) and Tc(1b), each at least partially, to the first condensate drum CD(1),wherein from said first 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 stream 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 from said second condensate drum CD(2), which is fed as thestream 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).]2nd aspect - Chemical production unitA second aspect of the present invention relates to a chemical production unit for carrying out the process according to the first aspect of the invention, the chemical production unit comprising- a rectification column D comprising-- inlet means, preferably in D’s lower part, for feeding streams W(i) or one or more combined streamthereof into D; -- outlet means, preferably in D’s upper part, for removing a vapor stream V or divided streams thereof,comprising at least a gaseous stream G and at a stream T(1), from the top of D;- optionally a stream dividing device So for dividing T(1) into sub streams thereof;- optionally 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 inparallel, 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);-- bottom reboilers VK(i);-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms stream removed from K(i);- means for passing the streams G(i) to the reactive distillation columns K(i);- means for passing the streams W(i) to the rectification column D;- one or more compressors CG(i) for compressing either the stream G and / or the streams G(i) and / or thestreams W(i);- a separation unit SU with inlet means for feeding at least a part of a stream P(i) into SU, outlet means for re-moving at least a part of a residue enriched in alkali metal methoxide A(i)OMe compared to P(i), preferably a residue containing solid alkali metal methoxide A(i)OMe, obtained in SU from SU, and outlet means for re-moving a methanol comprising stream MR(i) from SU; and- means for passing the stream MR(i), optionally splitted into at least two parts MR(ia) and MR(ib), into K(i),and / or for passing the stream MR(i) into D. All details, embodiments and preferred embodiments described above in the section related to the first aspect of the invention also apply to the chemical production unit of the second aspect of the invention.In some preferred embodiments of the chemical production unit, D further comprises- an intermediate reboiler V(1a);- a bottom reboiler V(1b).Preferably, the chemical production unit further comprises- a first compressor CT(1) for compressing T(1) or a part thereof;- a second compressor CT(2) for compressing a part stream of T(1) and / or for compressing a compressed substream of T(1) or a part thereof;- means for passing compressed sub streams of T(1) from CT(1) and / or CT(2) as heating medium through inter-mediate reboiler V(1a) and bottom reboiler V(1b) of D.In some preferred embodiments, the chemical production unit comprises a third compressor CT(3) for compressingsub streams of T(1) or for compressing compressed sub streams of T(1).In some preferred embodiments of the chemical production unit, the reactive distillation columns K(i) comprise bot-tom reboilers VK(i) and the chemical production unit comprises means for passing compressed sub streams of T(1) as heating medium through one or more bottom reboilers VK(i), wherein preferably at least parts of one or morestreams P(i) are also passed through the one or more bottom reboilers VK(i). Said at least parts of one or morestreams P(i) are, after passage through the one or more bottom reboilers VK(i), returned into K(i), wherein the re-turned at least parts of one or more streams P(i) have, due to the passage through the one or more bottom reboilers VK(i) a higher temperature compared to the bottoms streams P(i) before passage through the one or more bottomreboilers VK(i). Preferably, said at least parts of one or more streams P(i), which are passed through the one or morebottom reboilers VK(i) are different from the part of a stream P(i) fed into SU. The division is done or doable by the stream dividing means for separating a stream P(i) from the bottoms stream removed from K(i).In some preferred embodiments, the chemical production unit comprises means for passing condensed sub streamsof T(1) after passage through intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i) into D, the means preferably comprising- at least one condenser, preferably a condenser V(2) and optionally a further condenser V(3) arranged down-stream of V(2), having inlet means for receiving condensed sub streams of T(1) after passage through inter- mediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i), 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 production unit comprises inlet means for feeding a methanol streamM into D. Preferably, the separation unit SU is an evaporation unit or a partial evaporation unit. Preferably the chemical production unit comprises at least one condensation unit CU and means for passing the stream MR(i) into said condensation unit CU and means for obtaining from CU the stream MR(i) in liquid form, and forpassing the stream MR(i) in liquid form, optionally splitted into at least two liquid parts MR(ia) and MR(ib), into K(i)and / or into D.3rd aspect - UseA third aspect of the invention relates to a use of a chemical production unit according to the second aspect of theinvention or of a process according to the first aspect of the invention 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.All details, embodiments and preferred embodiments described above in the section related to the first aspect of the invention as well as in the section related to the second aspect of the invention also apply to the use of the third as- pect of the invention. The present invention is further illustrated by the following set of embodiments and combinations of embodiments resulting from the dependencies and back-references as indicated. In particular, it is noted that in each instancewhere a range of embodiments is mentioned, for example in the context of a term such as "The integrated process of any one of embodiments 1 to 4", every embodiment 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 inte-grated process of any 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 thedescription directed to general and preferred aspects of the present invention.1. An integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide andmethanol and for preparing solid alkali metal methoxide A(i)OMe, comprisingproviding 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; 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 metha- nol, thereby obtaining n top streams W(i) comprising methanol and water; and obtaining n mixtures P(i) com- prising alkali metal methoxide A(i)OMe and methanol as bottom streams (n bottoms streams P(i));the process further comprising (a) subjecting at least a part of at least one of the n bottoms streams P(i) comprising alkali metal methoxideA(i)OMe and methanol in a separation unit SU to a solid separation, obtaining a residue enriched in alkalimetal methoxide A(i)OMe compared to P(i), preferably containing solid alkali metal methoxide A(i)OMe, and a stream MR(i) comprising methanol;(b) feeding at least a part of the stream comprising methanol MR(i) obtained in (a) to at least one reactivedistillation column K(i) and / or feeding at least a part of the stream comprising methanol MR(i) obtained in(a) to rectification column D.2. The integrated process of embodiment 1, wherein in (a), in the range of from 10 to 100 weight-%, of at leastone of the n bottoms streams P(i) comprising alkali metal methoxide A(i)OMe and methanol are subjected in the separation unit SU to solid separation, based on the total weight of the at least one of the n bottomstreams P(i) being 100 weight-%.3. The integrated process of embodiment 1or 2, wherein in (b), at least 50 weight-%, preferably at least 60weight-%, more preferably at least 70 weight-%, more preferably at least 80 weight-%, more preferably at least 90 weight-%, more preferably at least 95 weight-%, more preferably at least 98 weight-%, more prefera-bly at least 99 weight-%, more preferably at least 99.5 weight-%, of the stream comprising methanol MR(i) ob-tained in (a) are fed to at least one reactive distillation column K(i) and / or to rectification column D.4. The integrated process of any one of embodiments 1 to 3, wherein the solid separation in (a) is done by atleast partial evaporation, wherein the separation unit SU is preferably an evaporation unit or a partial evapora-tion unit.5. The integrated process of any one of embodiments 1 to 4, wherein the solid separation in (a) is done at apressure in the range of from 0.5 to 5 bar(abs), preferably in the range of from 0.6 to 4 bar(abs), more prefera- bly in the range of from 0.7 to 3 bar(abs), more preferably in the range of from 0.8 to 1.5 bar(abs).6. The integrated process of any one of embodiments 1 to 5, wherein the solid separation in (a) is done at a tem-perature in the range of from 50 to 200 °C, preferably in the range of from 60 to 180°C, more preferably in therange of from 65 to 160°C.7. The integrated process of any one of embodiments 1 to 6, wherein the residue enriched in alkali metal meth-oxide A(i)OMe compared to P(i) comprises at the outmost 10 weight-%, preferably at the outmost 5 weight-%, more preferably at the outmost 1 weight-% of methanol, based on the total weight of the residue being 100 weight-%.8. The integrated process of any one of embodiments 1 to 7, wherein the stream MR(i) comprises less than 0.1weight-%, preferably less than 0.01 weight-%, more preferably less than 0.001 weight-%, of alkali metal meth-oxide A(i)OMe, based on the total weight of the stream MR(i) being 100 weight-%, wherein in (b), preferably at least a part of the stream comprising methanol MR(i) obtained in (a) is fed to rectification column D, more pref- erably the stream comprising methanol MR(i) obtained in (a) is fed to rectification column D.9. The integrated process of embodiment 8, wherein MR(i) has a methanol concentration cMeOH(MR(i)) and is fedto rectification column D at a position P(1), where the MeOH concentration at that position P(1) within the rec-tification column D cMeOH(P1) is preferably about equal to cMeOH(MR(i)) with 0.95 ≤ cMeOH(MR(i)) / cMeOH(P1) ≤ 1.05.10. The integrated process of any one of embodiments 1 to 8, wherein the stream MR(i) comprises in the range offrom 0.001 to 10 weight-%, preferably in the range of from 0.005 to 5 weight-%, more preferably in the range of from 0.01 to 2 weight-% of alkali metal methoxide A(i)OMe, based on the total weight of the stream MR(i)being 100 weight-%, wherein in (b), preferably at least a part of the stream comprising methanol MR(i) ob- tained in (a) is fed to at least one reactive distillation column K(i), more preferably the stream comprising methanol MR(i) obtained in (a) is fed to the same reactive distillation column K(i) from which the bottomsstream P(i) comprising alkali metal methoxide A(i)OMe and methanol, subjected to separation in a) is taken.11. The integrated process of embodiment 10, wherein feeding at least a part of the stream comprising methanolMR(i) obtained in (a) in (b) is done into the upper part, preferably the top, of the at least one, preferably same, reactive distillation column K(i).12. The integrated process of any one of embodiments 1 to 11, wherein the stream MR(i) is fed in b) to at leastone reactive distillation column K(i) and / or to rectification column D as a liquid stream.13. The integrated process of embodiment 12, wherein the stream MR(i) comprising methanol obtained in a) issubjected to condensation, thereby obtaining MR(i) in liquid form; wherein condensation is done is preferably done in an apparatus operated with a cooling medium, wherein condensation is more preferably complete.14. The integrated process of any one of embodiments 1 to 13, wherein (b) comprises(b.1) splitting the stream comprising methanol MR(i) obtained in (a), optionally the stream MR(i) in liquid form,into at least two sub-streams MR(ia) and MR(ib); (b.2) feeding sub-stream MR(ia) into at least one reactive, preferably the same, distillation column K(i);(b.3) feeding sub-stream MR(ib) into the same reactive distillation column K(i) as sub-stream MR(ia) but at adifferent position than sub-stream MR(ia), preferably at a position in the upper part, preferably at the top, of the same reactive distillation column K(i).15. The integrated process of embodiment 14, wherein the ratio of the mass flow rateof sub-stream MR(ia) to the mass flow rate of sub-stream MR(ib) is in the range of from 1:10 to 10:1, preferably in the range of from 0.2:1 to 0.95:1, more preferably in the range of from 0.3:1 to 0.9:1¸ more preferably in the range of from 0.4:1 to 0.8:1 more preferably in the range of from 0.5:1 to 0.6:1.16. The integrated process of any one of embodiments 1 to 15, wherein n is 2.17. The integrated process of embodiment 16, wherein a stream H(1) comprises dissolved sodium hydroxide anda stream H(2) comprises dissolved potassium hydroxide, wherein sodium methoxide is prepared in the reac- tive 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.18. The integrated process of embodiment 17, wherein the part of the bottoms streams P(1) from reactive distilla-tion column K(1) comprising sodium methoxide NaOMe and methanol is subjected in a separation unit SU(1)to the solid separation in (a), obtaining a residue enriched in NaOMe compared to P(1), preferably containingsolid sodium methoxide NaOMe, and a stream MR(1) comprising methanol; and in (b), at least a part of the stream comprising methanol MR(1) obtained in (a) is fed to the reactive distillation column K(1) and / or the partof the bottoms streams P(2) from reactive distillation column K(2) comprising potassium methoxide KOMe andmethanol is subjected in a separation unit SU(2) to the solid separation in (a), obtaining a residue enriched in KOMe compared to P(2), preferably containing solid potassium methoxide KOMe, and a stream MR(2) com- prising methanol; and in (b), at least a part of the stream comprising methanol MR(2) obtained in (a) is fed to the reactive distillation column K(2).19. The integrated process of embodiment 17 or 18, wherein the stream MR(1) is fed to the to the reactive distilla-tion column K(1) as a liquid stream and / or the stream MR(2) is fed to the reactive distillation column K(2) as aliquid stream.20. The integrated process of any one of embodiments 17 to 19, wherein the stream MR(1) comprising methanolobtained in a) is subjected to condensation, thereby obtaining MR(1) in liquid form, and / or the stream MR(2) comprising methanol obtained in a) is subjected to condensation, thereby obtaining MR(2) in liquid form;wherein condensation is done is preferably done in an apparatus operated with a cooling medium, wherein condensation is more preferably complete.21. The integrated process of any one of embodiments 17 to 20, wherein (b) comprises(b.1) splitting the stream comprising methanol MR(1), optionally MR(1) in liquid form, obtained in (a) into atleast two sub-streams MR(1a) and MR(1b); (b.2) feeding subs-stream MR(1a) into reactive distillation column K(1);(b.3) feeding subs-stream MR(1b) into reactive distillation column K(1) at a different position than MR(1a),preferably at a position in the upper part, preferably at the top, of the same reactive distillation columnK(1).22. The integrated process of any one of embodiments 1 to 121 further comprising(c) obtaining a vapor phase V comprising methanol at the top of the rectification column D, said vaporphase V having a pressure pV and a temperature TV; (d) preparing at least two streams from the vapor phase V, comprising a vapor stream G having a pres-sure pGand a temperature TGwith 0.95 ≤ pG / pV≤ 1.00, and further comprising a vapor stream T(1), said vapor stream T(1) having a pressure pT(1a) and a temperature TT(1a) with pT(1a) > pV;(e) passing at least a part of the stream T(1) as a heating medium through a reboiler V(1) of the rectifica-tion column D, preferably through an intermediate reboiler V(1a) of the rectification column, obtaining a, preferably at least partially condensed, stream TC(1) having a temperature TTc(1a)with TTc(1a)< TT(1a); (f) feeding at least a part of the stream TC(1) into the rectification column D.23. The integrated process of embodiment 22 further comprising(g) preparing the n streams G(i) from the vapor stream G, each of the streams G(i) having 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 re- spective reactive distillation column K(i).The integrated process of embodiment 22 or 23 further comprising(h) feeding at least a part of one or more of the top streams W(i) into the rectification column D.The integrated process of embodiment 24, wherein (h) comprisesfeeding at least a first stream W(1) and a second stream W(2) at least partially into the rectification column D, comprising(h.1) feeding at least a part of the stream W(1) into the lower part of the rectificationcolumn D at a position I(1);(h.2) feeding at least a part of the stream W(2) into the lower part of the rectification column D at a positionI(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 internals.The integrated process of embodiment 25, wherein below the position I(2) the rectification column D isequipped with internals.The integrated process of embodiment 26, wherein feeding at least a part of one or more of the top streamsW(i) into the rectification column D according to (h) comprises(h.1’) feeding at least a part of the top stream W(1) into the lower part of the rectification column D at a posi-tion I(1);(h.2’) at least partially condensing at least a part of the top stream W(2), obtaining an at least partially con-densed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification column D at a position I(2).The integrated process of embodiment 27, further comprising(i) feeding a stream M comprising methanol into the rectification column D at a position I(M).The integrated process of embodiment 28, wherein (h.2’) comprises(h.2’.1) passing the vapor stream W(2) having a temperature TW(2) through at least one heat exchangerE, obtaining an at least partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2), and(h.2’2) feeding at least a part of the at least partially condensed stream WC(2) into the rectification col-umn D at the position I(2); and wherein (i) comprises(i.1) passing the stream M having a temperature TM1 through one or more of said at least one of heatexchangers E, obtaining a stream M having a temperature TM2 with TM2 > TM1, and(i.2) feeding the stream M having the temperature TM2 into the upper part of the rectification columnD at the position I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1).30. The integrated process of embodiment 28, wherein (h.2’) comprises(h.2’.1’) passing the vapor stream W(2) having a temperature TW(2) through a heat exchanger E(1a), ob-taining a partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2); (h.2’.2’) feeding at least a part of the at least partially condensed stream WC(2) into the lower part of therectification column D at the position I(2); and wherein (i) comprises (i.1’) passing the stream M having the temperature TM1 through the heat exchanger E(1a), obtaining thestream M having the temperature TM2; (i.2’) feeding the stream M having the temperature TM2 into the upper part of the rectification column D at theposition I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1).31. The integrated process of embodiment 28, wherein (h.2’) comprises(h.2’.1’’) passing the vapor stream W(2) having a temperature TW(2) through a heat exchanger E(1a), ob-taining a partially condensed stream WC1(2) having a temperature TWC1(2)with TWC1(2)< TW(2); (h.2’.2’’) passing the stream WC1(2) having the temperature TWC1(2) through a heat exchanger E(1b), ob-taining a, preferably completely condensed, stream WC2(2) having a temperature TWC2(2)with TWC2(2) < TWC1(2); (h.2’.3’’’) feeding at least a part of the stream WC2(2) into the lower part of the rectification column D atthe position I(2); and wherein (i) comprises (i.1’’) passing the stream M having the temperature TM1 through the heat exchanger E(1a), obtaining thestream M having the temperature TM2; (i.2’’) feeding at least a part of the stream M having the temperature TM2 into the upper part of the rectifica-tion column D at the position I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1).32. The integrated process of embodiment 28, wherein (h) and (i) comprise passing the vapor stream W(2) havinga temperature TW(2)through at least one heat exchanger E(2), obtaining an at least partially, preferably essen- tially completely, condensed stream WC(2) having a temperature TWC(2) with TWC(2) < TW(2); and admixing thestream M, prior to feeding it into the rectification column D at the position I(M), with at least a part of the stream WC(2), wherein I(M) = I(2), wherein preferably, I(M) is above I(1).33. The integrated process of embodiment 28, wherein (h) and (i) comprise admixing the vapor stream W(2) hav-ing a temperature TW(2) with the stream M having a temperature TM1 with TW(2) > TM1, thereby at least partially condensing the stream W(2), and feeding the stream obtained from mixing into the rectification column D at the position I(M), wherein I(M) = I(2), wherein preferably, I(M) is above I(1).The integrated process of any one of embodiments 22 to 33, wherein rectification column D is operated withtop vapor recompression, wherein preferably realizing a 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.The integrated process of any one of embodiments 22 to 34, wherein (e) comprises passing stream T(1)through a first compression unit CT(1), obtaining a compressed stream T(1a), and passing the compressed stream T(1a) through a reboiler V(1), preferably an intermediate reboiler V(1a) of rectification column D, ob- taining a condensed stream Tc(1a).The integrated process of embodiment 35, wherein Tc(1a), at least partially, is fed to a first condensate drumCD(1), wherein from said first condensate drum CD(1), a gas stream T(1g) and a liquid stream T(1l) are re- moved, said gas stream T(1g) being fed into the condenser V(2) and said liquid stream T(1l) being combinedwith the liquid streams T(2l) and (T2gl) in depressurized form, obtaining a combined liquid stream which is fedas the stream T(3) into the top of the rectification column D.The integrated process of any one of embodiments 22 to 36, wherein (e) comprises(e.1) splitting vapor stream T(1) into at least two streams; passing a first part stream of T(1) through the firstcompression unit CT(1), obtaining a compressed stream T(1a), and passing a second part stream of T(1) through a second compression unit CT(2), obtaining a compressed stream T(1b);(e.2) passing the compressed stream T(1a) through an intermediate reboiler V(1a) of rectification column D,obtaining a condensed stream Tc(1a), and passing the compressed stream T(1b) through a bottoms reboiler V(1b) of rectification column D, obtaining a condensed stream Tc(1b).The integrated process of embodiment 37, wherein Tc(1a) and / or Tc(1b), preferably Tc(1a) and Tc(1b), each atleast partially, is / are fed to a first condensate drum CD(1), wherein from said first condensate drum CD(1), agas stream T(1g) and a liquid stream T(1l) are removed, said gas stream T(1g) being fed into the condenserV(2) and said liquid stream T(1l) being combined with the liquid streams T(2l) and (T2gl) in depressurized form, obtaining a combined liquid stream which is fed as the stream T(3) into the top of the rectification col- umn D.A chemical production unit for carrying out the process according to any one of embodiments 1 to 38, com-prising- a rectification column D comprising-- inlet means, preferably in D’s lower part, for feeding streams W(i) or one or more combinedstream thereof into D;-- outlet means, preferably in D’s upper part, for removing a vapor stream V or divided streamsthereof, comprising at least a gaseous stream G and at a stream T(1), from the top of D; -optionally a stream dividing device So for dividing T(1) into sub streams thereof;- optionally 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 ar-ranged 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);-- bottom reboilers VK(i);-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms stream removed fromK(i); -means for passing the streams G(i) to the reactive distillation columns K(i);- means for passing the streams W(i) to the rectification column D;- one or more compressors CG(i) for compressing either the stream G and / or the streams G(i) and / or thestreams W(i); -a separation unit SU with inlet means for feeding at least a part of a stream P(i) into SU, outlet meansfor removing at least a part of a residue enriched in alkali metal methoxide A(i)OMe compared to P(i), preferably a residue containing solid alkali metal methoxide A(i)OMe, obtained in SU from SU, and out-let means for removing a methanol comprising stream MR(i) from SU; -means for passing the stream MR(i), optionally splitted into at least two parts MR(ia) and MR(ib), intoK(i), and / or for passing the stream MR(i) into D.40. The chemical production unit of embodiment 39, wherein D further comprises- an intermediate reboiler V(1a);- a bottom reboiler V(1b).41. The chemical production unit of embodiment 40 further comprising -a first compressor CT(1) for compressing T(1) or a part thereof;- a second compressor CT(2) for compressing a part stream of T(1) and / or for compressing a com-pressed sub stream of T(1) or a part thereof; -means for passing compressed sub streams of T(1) from CT(1) and / or CT(2) as heating mediumthrough intermediate reboiler V(1a) and bottom reboiler V(1b) of D;42. The chemical production unit of embodiment 41 comprising a third compressor CT(3) for compressing substreams of T(1) or for compressing compressed sub streams of T(1).43. The chemical production unit of embodiment 41 or 42, wherein the reactive distillation columns K(i) comprisebottom reboilers VK(i) and the chemical production unit comprises means for passing compressed sub streams of T(1) as heating medium through one or more bottom reboilers VK(i), wherein preferably at least parts of one or more streams P(i) are also passed through the one or more bottom reboilers VK(i).44. The chemical production unit of any one of embodiment 40 to 43 comprising means for passing condensedsub streams of T(1) after passage through intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i) into D, the means preferably comprising -at least one condenser, preferably a condenser V(2) and optionally a further condenser V(3) arrangeddownstream of V(2), having inlet means for receiving condensed sub streams of T(1) after passage through intermediate reboiler V(1a) and / or bottom reboiler V(1b) and / or bottom reboilers VK(i), and hav- ing 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.45. The chemical production unit of any one of embodiment 39 to 44 comprising inlet means for feeding a metha-nol stream M into D.46. The chemical production unit of any one of embodiment 39 to 45 wherein the separation unit SU is an evapo-ration unit or a partial evaporation unit.47. The chemical production unit of any one of embodiment 39 to 46 comprising at least one condensation unitCU and means for passing the stream MR(i) into said condensation unit CU and means for obtaining from CU the stream MR(i) in liquid form, and for passing the stream MR(i) in liquid form, optionally splitted into at least two liquid parts MR(ia) and MR(ib), into K(i) and / or into D.48. Use of a chemical production unit according to any one of embodiments 39 to 47 or of a process according toany one of embodiments 1 to 38 for simultaneously producing n mixtures P(i) comprising alkali metal methox- ide 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 concentra- tions. The present invention is further illustrated by the following reference examples, comparative examples, and exam- ples. Examples1. Reference Example 1: Simultaneous production of sodium methoxide andpotassium methoxide without top vapor recompression in rectification col- umn DFig.1 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) com-prising KOMe and MeOH according to Reference Example 1. Regarding the operating 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 1b 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 waterf(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), was calculated. In this calculation, the water contents of P(1) and P(2), both beingless than 1000 weight-ppm, were neglected. According to this calculation, fMeOH(P(1)) was the mass flow rate ofMeOH 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 flowrate 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), was calculated. In this calculation, the water contents of P(1) and P(2), both being lessthan 1000 weight-ppm, were neglected.1.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) was the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) was the mass flowrate of water contained in the stream H(2) and fH2O(M) was the mass flow rate of water contained in thestream 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 potassium methoxide with top vapor recompression (first compression unit) for intermediate reboiler in rectification column DFig.2 shows a process scheme for preparing a mixture P(1) comprising NaOMe and MeOH and a mixture P(2) com-prising KOMe and MeOH according to Reference Example 2. Regarding the operating 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, reference is made to Table 2b below.The use of vapor recompression reduced 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 demanddecreased to 20 %. But about 10 % (depending on the pressure) of the energy which was transferred in V(1a) wasneeded as power for the compressor CT(1). All in all, there was already some energy saving by using vapor recom-pression. 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) 2.2320 Temperature at the bottom / °C 124Column D Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8th25 Mfed to theoretical stage from bottom 42thPressure at outlet of CT(1) / bar(abs) 530 Pressure at the top / bar(abs) 2.15Temperature at the top / °C 8935 Column K(1)Pressure at the bottom / bar(abs) 2.3Temperature at the bottom / °C 117Number of trays 4040 Pressure at the top / bar(abs) 2.15Temperature at the top / °C 8945 Column 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 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 water contents of P(1) and P(2), both beingless than 1000 weight-ppm, were neglected. According to this calculation, fMeOH(P(1)) was the mass flow rate ofMeOH 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)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), were calculated. In this calculation, the water contents of P(1) and P(2), both beingless than 1000 weight-ppm, were neglected.2.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) was the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) was the mass flow rate of water contained in the stream H(2) and fH2O(M) was 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: Production of solid Na methylate and recycling of methanol into K(1)Sodium methoxide and potassium methoxide with top vapor recompression (first compression unit) for intermediatereboiler in rectification column D were prepared as in Reference Example 2. Contrary to Reference Example 2, andas shown in Fig.3, the stream comprising Na methylate from reactive column K(1) was directly subjected to evapora-tion, i.e. crystallization, in a separation unit SU, wherein the obtained methanol containing stream MR(1) in liquid formafter condensation was recycled back in to K(1) after separation into two sub-streams, wherein a sub-stream MR(1a)was fed into K(1) in the bottom and another sub-stream MR(1b) was fed into K(1) at the top. The crystalline, Na meth-ylate containing solid obtained from crystallization contained 1 weight-% of MeOH, and the methanol containingstream recycled back in to K(1) contained 1 weight-% of Na methylate and was free of water.Regarding the operating conditions of the rectification 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 D Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of C(3) / 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 CD(2) streams H(1): NaOH 50 weight-% in water H(2): KOH 48 weight-% in water f(G(1)) / f(H(1)) 13.6f(G(2)) / f(H(2)) 9.03f(MR(1)) / f(H(1)) 1.62f(MR(1b)) / f(MR(1a)) 1.85Ratios of f(M(2)) / f(H(2)) 0.40mass flow rates f(T(3)) / f(G) *) 1.1of streams f(P(1)) / f(H(1)) 2.3f(P(2)) / f(H(2)) 1.86f(waste gas) / f(G) *) < 0.0015f(T(1)) / f(T(2)) 2.87*) 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 water contents of P(1) and P(2), both beingless than 1000 weight-ppm, were neglected. According to this calculation, fMeOH(P(1)) was the mass flow rate ofMeOH 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) - fMeOH(MR(1))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 lessthan 1000 weight-ppm, were neglected.3.5 f(water) = fH2O(H(1)) + fH2O(H(2)) + fH2O(M) - fH2O(waste gas)fH2O(H(1)) was the mass flow rate of water contained in the stream H(1) and fH2O(H(2)) was the mass flow rate of water contained in the stream H(2) and fH2O(M) was 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)4. Example 2: Production of solid Na methylate and recycling ofmethanol in D Sodium methoxide and potassium methoxide with top vapor recompression (first compression unit) for intermediate reboiler in rectification column D were prepared as in Reference Example 2. Contrary to Reference Example 2, andas shown in Fig.4, the stream comprising Na methylate from reactive column K(1) was directly subjected to evapora-tion, i.e. crystallization. A crystalline Na methylate was obtained, which contained 1 weight-% of MeOH, and a metha-nol containing stream MR(1), which contained 1 weight-% of Na methylate and was free of water. Said methanol con-taining stream MR(1) in liquid form after condensation was transferred into rectification column D. Regarding the operating conditions of the rectification column D and of the reactive distillation columns K(1) and K(2), reference is made to Table 4a below. Regarding the relative mass flow rates, reference is made to Table 4b below.Comparing Example 1 and Reference Example 3, it was noted that when the methanol containing stream MR(1) wastransferred into rectification column D, the remaining 1 weight-% of Na methylate contained therein reacted in columnD back to NaOH, which left the column D together with the bottoms streams, resulting in a loss of 2.4 weight% Namethylate based on the total weight of Na methylate produced being 100 weight-%. Furthermore, the waste waterstream contained 1.3 weight-% of NaOH. Table 4a Operating conditions of the columns D, K(1) and K(2) Column D Pressure at the top / bar(abs) 2.1Temperature at the top / °C 84Pressure at the bottom / bar(abs) 2.23Temperature at the bottom / °C 124Theoretical stages 50W(1), W(2) to theoretical stage from bottom 8thM fed to theoretical stage from bottom 42thPressure at outlet of C(3) / 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 4bRelationships between the mass flow rates f of the different streamsSpecified: H(1), H(2) Definition of M(1), M(2): part of condensate from CD(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) *) 0.95of 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)) 3.95*) 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 MeOHcontained in the stream P(1), fMeOH(P(2)) is the mass flow rate of MeOH contained in the stream P(2), fMeOH(water) isthe mass flow rate of MeOH contained in the water stream, and fMeOH(waste gas) is the mass flow rate of MeOH con- tained in the waste gas stream:fMeOH(M) = fMeOH(P(1)) + fMeOH(P(2)) + fMeOH(water) + fMeOH(waste gas) - fMeOH(MR(1))4.1 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 / kg4.2 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 / kg4.3 fMeOH(water) = 0.001 * f(water) (maximum value)4.4 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.4.5 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:4.5.1 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 / kg4.5.2 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 / kg4.5.3 fH2O(M) = 0.001 * f(M)4.5.4 fH2O(waste gas) = 0 (neglected)Short description of the FiguresFig.1 shows a schematic overview of a comparative process as used in Reference Example 1.Fig.2 shows a schematic overview of a comparative process with a first compression unit CT(1) as used inReference Example 2.Fig.3 shows a schematic overview of an inventive process as in Example 1 – based on Fig.2 - includingseparation unit SU downstream to reactive distillation column K(1), from which solid A(1)OMe (i.e. Na- OMe) are obtained and a methanol containing stream MR(1), the latter being subsequently fed as stream MR(1) into K(1), wherein it is shown that MR(1) is divided into two streams MR(1a) and MR(1b),which are fed to K(1) at different positions of K(1).Fig.4 shows a schematic overview of a comparative process as in Reference Example 3 – based on Fig.2 -including separation unit SU downstream to reactive distillation column K(1) and subsequent recycling of a methanol containing stream MR(1) from SU into rectification column D.Cited Literature- US 2002 / 0183566 A1- WO 2021 / 148174 A1- WO 2022 / 263032 A1- WO 2022 / 117803 A1- EP 1965879 A1

Claims

Claims1. An integrated process for simultaneously preparing n mixtures P(i) comprising alkali metal methoxide andmethanol and for preparing solid alkali metal methoxide A(i)OMe, 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; 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 metha- nol, thereby obtaining n top streams W(i) comprising methanol and water; and obtaining n mixtures P(i) com-prising alkali metal methoxide A(i)OMe and methanol as bottom streams (n bottoms streams P(i));the process further comprising (a) subjecting at least a part of at least one of the n bottoms streams P(i) comprising alkali metal methoxideA(i)OMe and methanol in a separation unit SU to a solid separation, obtaining a residue containing solid alkali metal methoxide A(i)OMe, and a stream MR(i) comprising methanol; (b) feeding at least a part of the stream comprising methanol MR(i) obtained in (a) as a liquid stream to atleast one reactive distillation column K(i) and / or feeding at least a part of the stream comprising methanol MR(i) obtained in (a) as a liquid stream to rectification column D.

2. The integrated process of claim 1, wherein the solid separation in (a) is done by at least partial evaporation,wherein the separation unit SU is preferably an evaporation unit or a partial evaporation unit.

3. The integrated process of claim 1 or 2, wherein the residue enriched in alkali metal methoxide A(i)OMe com-pared to P(i) comprises at the outmost 10 weight-%, preferably at the outmost 5 weight-%, more preferably at the outmost 1 weight-% of methanol, based on the total weight of the residue being 100 weight-%.

4. The integrated process of any one of claims 1 to 3, wherein the stream MR(i) comprises less than 0.1 weight-%, preferably less than 0.01 weight-%, more preferably less than 0.1 weight-%, of alkali metal methoxideA(i)OMe, based on the total weight of the stream MR(i) being 100 weight-%, wherein in (b), preferably at least a part of the stream comprising methanol MR(i) obtained in (a) is fed to rectification column D, more preferably the stream comprising methanol MR(i) obtained in (a) is fed to rectification column D.

5. The integrated process of claim 4, wherein MR(i) has a methanol concentration cMeOH(MR(i)) and is fed to recti-fication column D at a position P(1), where the MeOH concentration at that position P(1) within the rectificationcolumn D cMeOH(P1) is preferably about equal to cMeOH(MR(i)) with 0.95 ≤ cMeOH(MR(i)) / cMeOH(P1) ≤ 1.05.

6. The integrated process of any one of claims 1 to 3, wherein the stream MR(i) comprises in the range of from0.001 to 10 weight-%, preferably in the range of from 0.005 to 5 weight-%, more preferably in the range offrom 0.01 to 2 weight-% of alkali metal methoxide A(i)OMe, based on the total weight of the stream MR(i) be- ing 100 weight-%, wherein in (b), preferably at least a part of the stream comprising methanol MR(i) obtained in (a) is fed to at least one reactive distillation column K(i), more preferably the stream comprising methanol MR(i) obtained in (a) is fed to the same reactive distillation column K(i) from which the bottoms stream P(i) comprising alkali metal methoxide A(i)OMe and methanol, subjected to separation in a) is taken.

7. The integrated process of claim 6, wherein feeding at least a part of the stream comprising methanol MR(i)obtained in (a) in (b) is done into the upper part, preferably the top, of the at least one, preferably same, reac- tive distillation column K(i).

8. The integrated process of any one of claims 1 to 5, wherein (b) comprises(b.1) splitting the stream comprising methanol MR(i) obtained in (a) into at least two sub-streams MR(ia) andMR(ib); (b.2) feeding sub-stream MR(ia) into at least one reactive, preferably the same, distillation column K(i);(b.3) feeding sub-stream MR(ib) into the same reactive distillation column K(i) as sub-stream MR(ia) but at adifferent position than sub-stream MR(ia), preferably at a position in the upper part, preferably at the top, of the same reactive distillation column K(i).

9. The integrated process of any one of claims 1 to 8, wherein n is 2, wherein preferably a stream H(1) com-prises dissolved sodium hydroxide and a stream H(2) comprises dissolved potassium hydroxide, wherein more preferably, 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 column K(2) from which the stream W(2) is obtained.

10. The integrated process of any one of claims 1 to 9 further comprising(c) obtaining a vapor phase V comprising methanol at the top of the rectification column D, said vaporphase V having a pressure pVand a temperature TV; (d) preparing at least two streams from the vapor phase V, comprising a vapor stream G having a pres-sure pGand a temperature TGwith 0.95 ≤ pG / pV≤ 1.00, and further comprising a vapor stream T(1), said vapor stream T(1) having a pressure pT(1a)and a temperature TT(1a)with pT(1a)> pV; (e) passing at least a part of the stream T(1) as a heating medium through a reboiler V(1) of the rectifica-tion column D, preferably through an intermediate reboiler V(1a) of the rectification column, obtaining a, preferably at least partially condensed, stream TC(1) having a temperature TTc(1a) with TTc(1a) < TT(1a); (f) feeding at least a part of the stream TC(1) into the rectification column D;the integrated process preferably further comprising(g) preparing the n streams G(i) from the vapor stream G, each of the streams G(i) having 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 re- spective reactive distillation column K(i);the integrated process more preferably further comprising (h) feeding at least a part of one or more of the top streams W(i) into the rectification column D.

11. The integrated process of claim 10, wherein (h) comprisesfeeding at least a first stream W(1) and a second stream W(2) at least partially into the rectification column D, comprising (h.1) feeding at least a part of the stream W(1) into the lower part of the rectificationcolumn D at a position I(1); (h.2) feeding at least a part of the stream W(2) into the lower part of the rectification column D at a positionI(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 internals; or wherein feeding at least a part of one or more of the top streams W(i) into the rectification column D according to (h) comprises (h.1’) feeding at least a part of the top stream W(1) into the lower part of the rectification column D at a posi-tion I(1); (h.2’) at least partially condensing at least a part of the top stream W(2), obtaining an at least partially con-densed stream WC(2), and feeding at least a part of the stream WC(2) into the rectification column at a position I(2); and preferably further comprising (i) feeding a stream M comprising methanol into the rectification column D at a position I(M).

12. The integrated process of claim 11,wherein (h.2’) comprises (h.2’.1) passing the vapor stream W(2) having a temperature TW(2) through at least one heat exchangerE, obtaining an at least partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2), and (h.2’2) feeding at least a part of the at least partially condensed stream WC(2) into the rectification col-umn D at the position I(2); and wherein (i) comprises (i.1) passing the stream M having a temperature TM1 through one or more of said at least one of heatexchangers E, obtaining a stream M having a temperature TM2 with TM2 > TM1, and (i.2) feeding the stream M having the temperature TM2 into the upper part of the rectification columnD at the position I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1);or wherein (h.2’) comprises(h.2’.1’) passing the vapor stream W(2) having a temperature TW(2) through a heat exchanger E(1a), ob-taining a partially condensed stream WC(2) having a temperature TWC(2)with TWC(2)< TW(2);(h.2’.2’) feeding at least a part of the at least partially condensed stream WC(2) into the lower part of therectification column D at the position I(2); and wherein (i) comprises(i.1’) passing the stream M having the temperature TM1 through the heat exchanger E(1a), obtaining thestream M having the temperature TM2;(i.2’) feeding the stream M having the temperature TM2 into the upper part of the rectification column D at theposition I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1); or wherein (h.2’) comprises(h.2’.1’’) passing the vapor stream W(2) having a temperature TW(2) through a heat exchanger E(1a), ob-taining a partially condensed stream WC1(2) having a temperature TWC1(2)with TWC1(2)< TW(2);(h.2’.2’’) passing the stream WC1(2) having the temperature TWC1(2) through a heat exchanger E(1b), ob-taining a, preferably completely condensed, stream WC2(2) having a temperature TWC2(2)with TWC2(2) < TWC1(2);(h.2’.3’’’) feeding at least a part of the stream WC2(2) into the lower part of the rectification column D atthe position I(2); and wherein (i) comprises(i.1’’) passing the stream M having the temperature TM1 through the heat exchanger E(1a), obtaining thestream M having the temperature TM2;(i.2’’) feeding at least a part of the stream M having the temperature TM2 into the upper part of the rectifica-tion column D at the position I(M), wherein preferably, I(M) is above I(2) and I(2) is above I(1); or wherein (h) and (i) comprise passing the vapor stream W(2) having a temperature TW(2)through at least oneheat exchanger E(2), obtaining an at least partially, preferably essentially completely, condensed streamWC(2) having a temperature TWC(2)with TWC(2)< TW(2); and admixing the stream M, prior to feeding it into the rectification column D at the position I(M), with at least a part of the stream WC(2), wherein I(M) = I(2), wherein preferably, I(M) is above I(1); or wherein (h) and (i) comprise admixing the vapor stream W(2) having a temperature TW(2) with the stream M having a temperature TM1 with TW(2) > TM1, thereby at least partially condensing the stream W(2), and feeding the stream obtained from mixing into the rectification column D at the position I(M), wherein I(M) = I(2), wherein preferably, I(M) is above I(1).

13. A chemical production unit for carrying out the process according to any one of claims 1 to 12, comprising- a rectification column D comprising-- inlet means, preferably in D’s lower part, for feeding streams W(i) or one or more combinedstream thereof into D; -- outlet means, preferably in D’s upper part, for removing a vapor stream V or divided streamsthereof, comprising at least a gaseous stream G and at a stream T(1), from the top of D; -optionally a stream dividing device So for dividing T(1) into sub streams thereof;- optionally 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 ar-ranged 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);-- bottom reboilers VK(i);-- outlet means for removing a bottoms stream from K(i);-- a stream dividing means for separating a stream P(i) from the bottoms stream removed fromK(i); -means for passing the streams G(i) to the reactive distillation columns K(i);- means for passing the streams W(i) to the rectification column D;- one or more compressors CG(i) for compressing either the stream G and / or the streams G(i) and / or thestreams W(i); -a separation unit SU with inlet means for feeding at least a part of a stream P(i) into SU, outlet meansfor removing at least a part of a residue enriched in alkali metal methoxide A(i)OMe compared to P(i)obtained in SU from SU, and outlet means for removing a methanol comprising stream MR(i) fromSU; -means for passing the stream MR(i), optionally splitted into at least two parts MR(ia) and MR(ib), intoK(i), and / or for passing the stream MR(i) into D.

14. Use of a chemical production unit according to claim 13 or of a process according to any one of claims 1 to 12for simultaneously producing n mixtures P(i) comprising alkali metal methoxide and methanol, n being an inte- ger with n≥2 and i=1…n, wherein either at least 2 of the mixtures P(i) comprise different alkali metal methox- ides 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.

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