A preparation method of boric acid-10

Abstract

The present invention discloses a process for preparing boric acid 10, relating to the technical field of boric acid 10 preparation. The present invention involves reacting boron trifluoride 10 gas with lithium carbonate and ammonium carbonate. By adjusting the operating steps of the reaction process, the reaction proceeds smoothly, thereby increasing the purity of the boric acid 10 and reducing the boric acid preparation cycle.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of boric acid-10. Background Art

[0002] Boron-10 acid is the boron-10 isotope, chemical formula 10 Boron-10 acid is a white powdery crystal or scaly shiny crystal with a natural purity of 19.4%. It has strong neutron absorption and radiation protection functions. Boron-10 acid usually exists in the form of boron trifluoride ether complex or in solid form. 10 B, H3 10 Exists in BO3 form.

[0003] Currently, the preparation processes of boric acid-10 mainly include the following:

[0004] (1) Wu Changmei et al. used boron trifluoride-ether complex and calcium chloride as raw materials to react in methanol medium to generate trimethyl borate-10, and then simply distilled and collected the fraction at 58-60°C. Deionized water was added to the fraction to hydrolyze the obtained trimethyl borate-10 to generate boric acid-10, which was then separated to obtain the boric acid-10 product. The specific reaction mechanism is as follows:

[0005] (C2H5)2O·BF3+CaCl2→B(CH3O)3+CaF2+(C2H5)2O+HCl

[0006] B(CH3O)3+H2O→H3BO3+CH3OH

[0007] This method easily causes hydrolysis of trimethyl borate during the reaction and distillation process, thereby resulting in a low reaction yield of boronic acid-10 (H3BO3).

[0008] (2) Jin Hailing et al. reacted boron trifluoride 10-ether complex with sodium methoxide in a methanol medium to prepare trimethyl borate-10. After the reaction, the mixture was centrifuged to remove sodium fluoride. The supernatant was simply distilled and the fraction at 54-56°C was collected. Lithium chloride was added to the fraction for salting out. The supernatant obtained was trimethyl borate-10. After adding water, trimethyl borate-10 was hydrolyzed to generate boric acid-10. The boric acid product was obtained after concentration and drying. The specific reaction mechanism is as follows:

[0009] (C2H5)2O·BF3+3NaOCH3+CH3OH→[B(OCH3)3+CH3OH]+3NaF+(C2H5)2O

[0010] [B(OCH3)3+CH3OH]+LiCl→B(OCH3)3+[CH3OH+LiCl]

[0011] B(CH3O)3+H2O→H3BO3+CH3OH

[0012] This method easily causes hydrolysis of trimethyl borate during the reaction and distillation process, and consumes a large amount of lithium chloride during the salting-out process.

[0013] (3) Zhang Weijiang et al. heated the solid-liquid mixture of lithium carbonate and water to 40-80°C, then introduced boron trifluoride-10 gas into the solid-liquid mixture of lithium carbonate and water, stirred it until the boron trifluoride-10 was evenly dispersed in the solid-liquid mixture, and stopped aeration when the molar ratio of boron trifluoride-10 to lithium carbonate reached 1:1.5-1.6; the reaction was allowed to proceed for 10-25 hours to generate boric acid-10; the boric acid-10 solid was separated through separation, ion exchange, and crystallization. The reaction mechanism is as follows:

[0014] 2 10 BF3+3Li2CO3+3H2O→6LiF+2H3BO3+3CO2↑

[0015] This method is carried out in an aqueous system, avoiding the hydrolysis loss of the generated trimethyl borate due to the water content of the system. However, this method has the problems of long reaction cycle and difficult purification of the product. Therefore, how to further shorten the synthesis time and reduce the difficulty of purification is a hot topic of current research. Summary of the Invention

[0016] In view of the shortcomings of the prior art, the present invention provides a method for preparing boric acid-10, the reaction mechanism of which is as follows:

[0017] 2 10 BF3+(NH4)2CO3+3Li2CO3+2H2O→6LiF↓+2H3 10 BO3+4CO2↑+2NH3↑

[0018] The present invention is achieved by adopting the following technical solutions:

[0019] A process for preparing boric acid-10 comprises the following steps:

[0020] S1. Mix lithium carbonate and ammonium carbonate in a mass ratio of 1:3-5, pour into water, and stir evenly to obtain a carbonate aqueous solution;

[0021] S2, adding the carbonate aqueous solution into the reactor and heating it to 75-80°C;

[0022] S3, preheating boron trifluoride-10 gas and introducing it from the bottom of the reactor in step S2, at a rate such that the residence time of the boron trifluoride-10 gas in the carbonate aqueous solution is not less than 30 minutes; stopping the ventilation when the molar ratio of boron trifluoride-10 to lithium carbonate reaches 1:1.2-1.3;

[0023] S4. After the ventilation is completed, the reactor is kept at 75-80° C. for 2-3 hours;

[0024] S5. After the insulation is completed, the filtrate is filtered and collected, and the filtrate is a boric acid aqueous solution;

[0025] S6, distilling the filtrate under reduced pressure to obtain a concentrated solution;

[0026] S7. Adding boric acid-10 seed crystals to the concentrated solution, standing the solution for crystallization at low temperature, and filtering to obtain a boric acid-10 solid.

[0027] Preferably, in step S3, the boron trifluoride-10 gas is preheated to 40° C. to 55° C.

[0028] Preferably, the temperature of the static crystallization in step S7 is below 4°C.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] The present invention provides a preparation process of boron-10 acid. The process comprises reacting boron trifluoride-10 gas with lithium carbonate and ammonium carbonate. By adjusting the operating steps of the reaction process, the reaction can proceed smoothly, the purity of the boron-10 acid is improved, and the preparation cycle is reduced. DETAILED DESCRIPTION

[0031] The present invention will be further described below with reference to specific embodiments.

[0032] Example 1

[0033] A preparation process of boric acid-10, comprising the following steps:

[0034] S1. Mix 1 g of lithium carbonate and 3 g of ammonium carbonate, pour into 50 mL of water, and stir evenly to obtain a carbonate aqueous solution;

[0035] S2, adding the carbonate aqueous solution into the reactor and heating it to 80°C;

[0036] S3, preheating boron trifluoride-10 gas to 50° C. and then introducing the gas from the bottom of the reactor in step S2, wherein the boron trifluoride-10 gas is introduced at a rate such that the residence time of the boron trifluoride-10 gas in the carbonate aqueous solution is not less than 30 min; stopping the ventilation when the molar ratio of boron trifluoride-10 to lithium carbonate reaches 1:1.2;

[0037] S4. After the ventilation is completed, the reactor is kept at 80° C. for 2 h;

[0038] S5. After the insulation is completed, the filtrate is filtered and collected, and the filtrate is a boric acid aqueous solution;

[0039] S6, distilling the filtrate under reduced pressure to obtain a concentrated solution;

[0040] S7. Adding boric acid-10 seed crystals to the concentrated solution, standing the solution at 0° C. for crystallization, and filtering to obtain a boric acid-10 solid.

[0041] Example 2

[0042] A preparation process of boric acid-10, comprising the following steps:

[0043] S1. Mix 1 g of lithium carbonate and 4 g of ammonium carbonate, pour into 50 mL of water, and stir evenly to obtain a carbonate aqueous solution;

[0044] S2, adding the carbonate aqueous solution into the reactor and heating it to 80°C;

[0045] S3, preheating boron trifluoride-10 gas to 40° C. and then introducing the gas from the bottom of the reactor in step S2, wherein the boron trifluoride-10 gas is introduced at a rate such that the residence time of the boron trifluoride-10 gas in the carbonate aqueous solution is not less than 30 min; stopping the ventilation when the molar ratio of boron trifluoride-10 to lithium carbonate reaches 1:1.2;

[0046] S4. After the ventilation is completed, the reactor is kept at 80° C. for 3 h;

[0047] S5. After the insulation is completed, the filtrate is filtered and collected, and the filtrate is a boric acid aqueous solution;

[0048] S6, distilling the filtrate under reduced pressure to obtain a concentrated solution;

[0049] S7. Add boric acid-10 seed crystals to the concentrated solution, let it stand at 0° C. for crystallization, and obtain boric acid-10 solid after filtering.

[0050] Example 3

[0051] A preparation process of boric acid-10, comprising the following steps:

[0052] S1. Mix 1 g of lithium carbonate and 5 g of ammonium carbonate, pour into 50 mL of water, and stir evenly to obtain a carbonate aqueous solution;

[0053] S2, adding the carbonate aqueous solution into the reactor and heating it to 80°C;

[0054] S3, preheating boron trifluoride-10 gas to 55° C. and then introducing the boron trifluoride-10 gas from the bottom of the reactor in step S2, wherein the boron trifluoride-10 gas is introduced at a rate such that the residence time of the boron trifluoride-10 gas in the carbonate aqueous solution is not less than 30 min; stopping the ventilation when the molar ratio of boron trifluoride-10 to lithium carbonate reaches 1:1.3;

[0055] S4. After the ventilation is completed, the reactor is kept at 75° C. for 3 h;

[0056] S5. After the insulation is completed, the filtrate is filtered and collected, and the filtrate is a boric acid aqueous solution;

[0057] S6, distilling the filtrate under reduced pressure to obtain a concentrated solution;

[0058] S7. Adding boric acid-10 seed crystals to the concentrated solution, standing the solution at 0° C. for crystallization, and filtering to obtain a boric acid-10 solid.

[0059] After testing, the boric acid-10 solids prepared in Examples 1-3 of the present invention had a purity greater than 99.0%, and the boric acid-10 yield was above 95%.

[0060] It should be noted that the above examples are only some specific embodiments of the present invention. Obviously, the present invention is not limited to the above examples and may have other variations. All variations directly or indirectly derived from the present disclosure by those skilled in the art should be considered to be within the scope of protection of the present invention.

Claims

1. A process for preparing boric acid-10, characterized in that: The following steps are involved: S1. Mix lithium carbonate and ammonium carbonate in a mass ratio of 1:3-5, pour into water, and stir evenly to obtain a carbonate aqueous solution; S2, adding the carbonate aqueous solution into the reactor and heating it to 75-80°C; S3, preheating boron trifluoride-10 gas and introducing it from the bottom of the reactor in step S2, at a rate such that the residence time of the boron trifluoride-10 gas in the carbonate aqueous solution is not less than 30 minutes; stopping the ventilation when the molar ratio of boron trifluoride-10 to lithium carbonate reaches 1:1.2-1.3; S4. After the ventilation is completed, the reactor is kept at 75-80° C. for 2-3 hours; S5. After the insulation is completed, the filtrate is filtered and collected, and the filtrate is a boric acid aqueous solution; S6, distilling the filtrate under reduced pressure to obtain a concentrated solution; S7, adding boron-10 acid seed crystals to the concentrate, allowing to stand at low temperature for crystallization, and filtering to obtain boron-10 acid solid; Step S3: preheating the boron trifluoride-10 gas to 40°C to 55°C.

2. The process for preparing boric acid-10 according to claim 1, wherein: The temperature of the crystallization during standing in step S7 is below 4°C.