US 11,629,415 B2Granted

Process for preparing sodium alkoxides

AssigneeEvonik Functional Solutions GmbH

InventorsMichael Horn, Felix Gärtner, Philip Heinrich Reinsberg, Rüdiger Teufert

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Abstract

A process for electrochemical preparation of sodium alkoxide is performed in an electrolysis cell having three chambers, wherein the middle chamber is separated from the cathode chamber by a solid-state electrolyte permeable to sodium ions, and from the anode chamber by a diffusion barrier. The geometry of the electrolysis cell protects the solid-state electrolyte permeable to sodium ions from acidic destruction by the pH of the anolyte that falls in the course of electrolysis. The anolyte used in the process is a brine also comprising carbonates and/or hydrogencarbonates, as well as NaCl. The process solves the problem that CO2 from these carbonates and/or hydrogencarbonates forms in the electrolysis cell during the electrolysis of this brine obtained from pretreatment. The process prevents the formation of a gas bubble in the electrolysis cell that disrupts electrolysis and reduces the contamination of the chlorine with CO2.

A process for preparing a solution Li of a sodium alkoxide NaOR in an alcohol ROI-1, in an electrolysis cell E, wherein E comprises at least one anode chamber KA, at least one cathode chamber KK, and at least one interposed middle chamber KM, the process comprising:

(a) routing a solution L2 comprising the alcohol ROH through the at least one cathode chamber KK,
(b) routing a neutral or alkaline, aqueous solution L3 comprising NaCl and at least one salt S selected from the group consisting of hydrogencarbonate and carbonate, through the at least one interposed middle chamber KM, then via a connection VAM, through the at least one anode chamber KA, and
(c) applying voltage between an anodic electrode EA and a cathodic electrode EK,
wherein (a), (b), and (c) are performed simultaneously,
wherein the at least one anode chamber KA comprises the anodic electrode EA and an outlet AKA,
wherein the at least one cathode chamber KK comprises the cathodic electrode EK, an inlet ZKK and an outlet AKK,
wherein the at least one interposed middle chamber KM comprises an inlet ZKM and a gas outlet G, wherein the at least one interposed middle chamber KM is separated from the at least one anode chamber KA by a diffusion barrier D and is separated from the at least one cathode chamber KK by a sodium cation-conducting solid-state electrolyte FK,
wherein the at least one anode chamber KA and the at least one interposed middle chamber KM are connected to one another by the connection VAM through which liquid can be routed from the at least one interposed middle chamber KM into the at least one anode chamber KA,
wherein the process affords the solution L1 at the outlet AKK, wherein the concentration of NaOR in the solution L1 is higher than in the solution L2,
wherein the process affords an aqueous solution L4 of NaCl at the outlet AKA, wherein the concentration of NaCl in the solution L4 is lower than in the solution L3, and wherein the total concentration of all salts S in the solution L1 is lower than in the solution L3,
wherein the process forms CO2 in the at least one interposed middle chamber KM, which is removed from the at least one interposed middle chamber KM via the gas outlet G, and
wherein R is an alkyl radical having 1 to 4 carbon atoms.

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Abstract

Claims14