A method can be used for producing alkali metal alcoholates in counter flow by reactive rectification. The alkali metal is selected from sodium and potassium. In a first part of the method, the alcohol is converted in counter flow with the respective alkali metal hydroxide. In a second part of the method, the mixture of alcohol and water obtained is separated in a rectification column, and the alcoholic vapour arising is condensed, as a result of which the temperature thereof increases. The energy dissipated during cooling of the condensed vapour is then used in the first part of the method. This permits an energy-efficient production of the alkali metal alcoholates concerned.

A process can be used for preparing sodium and potassium alkoxides. The process is characterized by two simultaneously implemented but spatially separated reactions of an alcohol ROH with NaOH, and ROH with KOH, to give sodium alkoxide and potassium alkoxide, respectively. The vapours formed in this case contain the alcohol used and water. The vapours are combined, and the resulting mixed vapour is fed to a common distillation with recovery of the alcohol.

Process for preparing metal alkoxides by means of transalcoholization, wherein a lower metal alkoxide is fed via a side feed into a reactive distillation column comprising a rectifying section situated above the feed and a stripping section situated below the feed; a higher alcohol is fed into the stripping section, the bottom and/or a bottoms circuit of the column; a solution of a higher metal alkoxide in the higher alcohol is taken off at the bottom of the column and/or from the bottoms circuit; and a vapor comprising lower alcohol is taken off at the top of the column, the vapor is at least partially condensed and a substream of the condensate is recycled to the top of the column as reflux. The process enables the preparation of metal alkoxides with a reduced energy requirement.

Process for preparing metal alkoxides by means of transalcoholization, wherein a lower metal alkoxide is fed via a side feed into a reactive distillation column comprising a rectifying section situated above the feed and a stripping section situated below the feed; a higher alcohol is fed into the stripping section, the bottom and/or a bottoms circuit of the column; a solution of a higher metal alkoxide in the higher alcohol is taken off at the bottom of the column and/or from the bottoms circuit; and a vapor comprising lower alcohol is taken off at the top of the column, the vapor is at least partially condensed and a substream of the condensate is recycled to the top of the column as reflux. The process enables the preparation of metal alkoxides with a reduced energy requirement.

A method can be used for producing alkali metal alcoholates in counter flow by reactive rectification. The alkali metal is selected from sodium and potassium. In a first part of the method, the alcohol is converted in counter flow with the respective alkali metal hydroxide. In a second part of the method, the mixture of alcohol and water obtained is separated in a rectification column, and the alcoholic vapour arising is condensed, as a result of which the temperature thereof increases. The energy dissipated during cooling of the condensed vapour is then used in the first part of the method. This permits an energy-efficient production of the alkali metal alcoholates concerned.

A process can be used for preparing sodium and potassium alkoxides. The process is characterized by two simultaneously implemented but spatially separated reactions of an alcohol ROH with NaOH, and ROH with KOH, to give sodium alkoxide and potassium alkoxide, respectively. The vapours formed in this case contain the alcohol used and water. The vapours are combined, and the resulting mixed vapour is fed to a common distillation with recovery of the alcohol.

A process for preparing metal alkoxides by transalcoholisation, comprising: feeding a lower metal alkoxide and a higher alcohol into a reactive distillation column; removing a solution of a higher metal alkoxide in the higher alcohol from the bottom of the column or from a recycle stream taken from the bottom of the column; and removing a gaseous lower alcohol from the top of the column, at least partially condensing the gaseous lower alcohol, and recirculating a part of the condensate to the top of the column; wherein an auxiliary alcohol is provided in the reactive distillation column, the boiling point of the auxiliary alcohol being between the boiling point of the lower alcohol and the boiling point of the higher alcohol at the pressure prevailing in the reactive distillation column. The process allows for high conversion of a lower metal alkoxide to a higher metal alkoxide while limiting the formation of solid deposits in the column, while having low energy requirements.

A method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme A: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the feed amount of the reactant alcohol; Scheme B: establishing a signal S1 which is responsive to a temperature in the rectifying section disposed above the feed of the metal methoxide; and manipulating in response to the signal S1 the heat supplied to the bottom of the reactive distillation column. The invention also relates to a method for controlling a reactive distillation column for effecting a transalcoholisation reaction, comprising feeding a metal methoxide into the reactive distillation column via a side feed; feeding a reactant alcohol into a lower part of the reactive distillation column; causing an auxiliary alcohol to be present in the reactive distillation column; and optionally replenishing the auxiliary alcohol via a side feed located above the feed of the reactant alcohol and below the top of the column; withdrawing methanol from the top of the reactive distillation column; and withdrawing a solution of a product metal alkoxide in the reactant alcohol from the bottom of the reactive distillation column; wherein the method comprises a process control scheme selected from: Scheme C: establishing a signal S2 which is responsive to a temperature at a point located between the feed of the metal methoxide and the bottom of the reactive distillation column; and manipulating in response to the signal S2 the feed amount of the reactant alcohol; Scheme D: establishing a signal S2 which is responsive to a temperature at a point located between the feed of the metal methoxide and the bottom of the reactive distillation column; and manipulating in response to the signal S2 the heat supplied to the bottom of the reactive distillation column. The methods of the invention allow for improved controlling of a reactive distillation column for effecting a transalcoholisation reaction.

Process for preparing metal alkoxides by means of transalcoholization, wherein a lower metal alkoxide is fed via a side feed into a reactive distillation column comprising a rectifying section situated above the feed and a stripping section situated below the feed; a higher alcohol is fed into the stripping section, the bottom and/or a bottoms circuit of the column; a solution of a higher metal alkoxide in the higher alcohol is taken off at the bottom of the column and/or from the bottoms circuit; and a vapor comprising lower alcohol is taken off at the top of the column, the vapor is at least partially condensed and a substream of the condensate is recycled to the top of the column as reflux. The process enables the preparation of metal alkoxides with a reduced energy requirement.

The present invention relates to a process for workup of a methanol/water mixture which is employed in the production of alkali metal methoxides in a reaction column. The mixture is distillatively separated in a rectification column. The vapours obtained at the upper end of the rectification column are compressed in at least two stages and the energy of the vapours compressed in each case is advantageously transferred to bottoms and side streams of the rectification column. This allows particularly energy-efficient use of the energy of the compressed vapours in the process according to the invention.

The process for workup of a methanol/water mixture is employed in the production of alkali metal methoxides in a reaction column, wherein methanol and alkali metal hydroxide solution are reacted with one another in countercurrent in a reaction column. Alkali metal methoxide dissolved in methanol is withdrawn at the lower end and a methanol/water mixture which is worked up with the workup process according to the invention is withdrawn at the upper end. The energy of the compressed vapours may additionally be used for operating the reaction column or for operating a reaction column in which a process for transalcoholization of alkali metal alkoxides is performed.