Thermal decomposition of magnesium chloride

Patent metadata

Field	Value
Publication number	US-11261467-B2
Application number	US-201515129431-A
Country	US
Kind code	B2
Filing date	Mar 30, 2015
Priority date	Apr 1, 2014
Publication date	Mar 1, 2022
Grant date	Mar 1, 2022

Abstract

A method for conversion of magnesium chloride into magnesium oxide and HCl, comprising the steps of
providing a magnesium chloride compound to a thermohydrolysis reactor, the reactor being at a temperature of at least 300° C., withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream from the thermohydrolysis reactor, wherein the magnesium chloride compound provided to the thermohydrolysis reactor is a solid magnesium chloride compound which comprises at least 50 wt. % of MgCl 2 .4H 2 O. The process accordingly is fast and can be operated in a manner which is efficient both as regards apparatus and energy. It can also be integrated in a process for converting a magnesium chloride solution.

First claim

The invention claimed is:

1. Method for conversion of magnesium chloride into magnesium oxide and HCl, comprising the steps of
subjecting a magnesium chloride solution to a drying step at a temperature of 100-160° C., which drying step forms a magnesium chloride compound comprising at least 50 wt. % of MgCl 2 .4H 2 O and comprising less than 40 wt. % of the total of magnesium chloride anhydrate, magnesium chloride monohydrate, and magnesium chloride dihydrate,
providing the magnesium chloride compound to a thermohydrolysis reactor, the reactor being at a temperature of at least 300° C., and
withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream from the thermohydrolysis reactor.

2. Method according to claim 1 , wherein at least 60 wt. % of the magnesium chloride compound is MgCl 2 .4H 2 O.

3. Method according to claim 1 , wherein the magnesium chloride compound comprises less than 30 wt. % of magnesium chloride hexahydrate.

4. Method according to claim 1 , wherein the thermohydrolysis reactor is at a temperature of at least 350° C. and/or at a temperature below 1000° C.

5. Method according to claim 1 , wherein the thermohydrolysis is carried out in the presence of a gas stream.

6. Method according to claim 1 , wherein the thermohydrolysis reactor is a tube reactor wherein the magnesium chloride compound enters the reactor at or near one end of the reactor, further indicated as the feed end, and product magnesium oxide is withdrawn at or near the other end of the reactor, further indicated as the product end, while a gas stream enters the reactor at or near the product end, and a gas stream comprising HCl is withdrawn at or near the feed end.

7. Method according to claim 1 , wherein the drying step is carried out at a temperature of 110-160° C.

8. Method according to claim 1 , wherein the drying step is carried out in the presence of HCl.

9. Method according to claim 8 , wherein the HCl present in the drying step is provided by providing the HCl-containing gas stream derived from the thermohydrolysis reactor to the drying step.

10. Method according to claim 1 further comprising, prior to the step of subjecting the magnesium chloride solution to the drying step, the steps of
subjecting a carbon source to a fermentation step to form a carboxylic acid, which fermentation step comprises the steps of fermenting a carbon source by means of a micro-organism in a fermentation broth to form carboxylic acid and neutralizing at least part of the carboxylic acid by adding a magnesium base selected from magnesium oxide and magnesium hydroxide, thereby obtaining a magnesium carboxylate,
subjecting the magnesium carboxylate to an acidification step wherein the magnesium carboxylate is contacted with HCl in an aqueous environment to form an aqueous mixture comprising carboxylic acid and magnesium chloride, and
subjecting the aqueous mixture comprising carboxylic acid and magnesium chloride to a separation step, to form a magnesium chloride solution and a product stream being an effluent comprising carboxylic acid.

11. Method according to claim 10 , comprising the step of recycling the magnesium oxide withdrawn from the thermohydrolysis reactor at least in part to the fermentation step.

12. Method according to claim 10 , wherein the HCl-containing gas stream derived from the thermohydrolysis reactor is provided to the drying step.

13. Method according to claim 12 , comprising the step of recycling the HCl-containing gas stream derived from the drying step at least in part to the acidification step.

14. Method according to claim 1 , wherein at least 80 wt. % of the magnesium chloride compound is MgCl 2 .4H 2 O.

15. Method according to claim 1 , wherein at least 90 wt. % of the magnesium chloride compound is MgCl 2 .4H 2 O.

16. Method according to claim 3 , wherein the magnesium chloride compound comprises less than 30 wt. % of the total of magnesium chloride anhydrate, magnesium chloride monohydrate and magnesium chloride dihydrate.

17. Method according to claim 3 , wherein the magnesium chloride compound comprises less than 20 wt. % of the total of magnesium chloride anhydrate, magnesium chloride monohydrate and magnesium chloride dihydrate.

18. Method according to claim 4 , wherein the thermohydrolysis reactor is at a temperature of at least 400° C. but below 800° C.

19. Method according to claim 4 , wherein the thermohydrolysis reactor is at a temperature of at least 400° C. but below 700° C.

20. Method for conversion of magnesium chloride into magnesium oxide and HCl, comprising the steps of:
providing a magnesium chloride compound to a thermohydrolysis reactor, the reactor being at a temperature of at least 300° C.; and,
withdrawing MgO from the thermohydrolysis reactor in solid form, and withdrawing a HCl containing gas stream from the thermohydrolysis reactor,
wherein the magnesium chloride compound provided to the thermohydrolysis reactor is a solid magnesium chloride compound which comprises at least 50 wt. % of MgCl 2 .4H 2 O and which comprises less than 40 wt. % of the total of magnesium chloride anhydrate, magnesium chloride monohydrate, and magnesium chloride dihydrate, and
wherein the method is conducted with a residence time, calculated from the provision of the magnesium chloride compound to the thermohydrolysis reactor to the removal of the corresponding magnesium oxide from the reactor, of at most 30 minutes.

21. The method according to claim 20 , wherein the thermohydrolysis reactor is at a temperature below 1000° C.

22. The method according to claim 20 , wherein the thermohydrolysis reactor is at a temperature below 800° C.

23. A method according to claim 10 comprising collecting product stream being an effluent comprising carboxylic acid, thereby obtaining a carboxylic acid.

24. The method according to claim 23 , wherein the obtained carboxylic acid is selected from the group consisting of mono, di- and tricarboxylic acids having at least two but no more than 6 carbon atoms (C2-C6 carboxylic acid).

25. The method according to claim 23 , wherein the obtained carboxylic acid is selected from the group consisting of lactic acid, succinic acid, propionic acid, 3-hydroxypropionic acid, 2-, 3-, and 4-hydroxybutyric acid, citric acid, fumaric acid, itaconic acid, adipic acid, acrylic acid, levulinic acid, maleic acid, 2,5-furandicarboxylic acid, mandelic acid, malic acid and tartaric acid.

26. The method according to claim 5 , wherein the gas stream provides heat to the thermohydrolysis reactor and carries HCl from the thermohydrolysis reactor.

27. The method according to claim 1 , wherein the drying step is performed by spray-drying.

Assignees

• Purac Biochem Bv

Inventors

• De Haan André Banier
• Bokhove Jeroen
• Laksmana Fesia Lestari

Classifications

• C01F5/10 Primary

  by thermal decomposition of magnesium chloride with water vapour · CPC title

• B01J8/067

  Heating or cooling the reactor (B01J8/062 takes precedence) · CPC title

• C12P7/40 Primary

  containing a carboxyl group {including Peroxycarboxylic acids} · CPC title

• C01B7/035

  Preparation of hydrogen chloride from chlorides · CPC title

• Y02P20/582

  Recycling of unreacted starting or intermediate materials · CPC title