Preparation method and application of high-purity hydrated rare earth halide

Abstract

The invention discloses a preparation method and application of a high-purity hydrated rare earth halide, the general formula of the hydrated rare earth halide in the method is REX3.xH2O, RE is a rare earth element, X is halogen, x is the number of crystal water, and x is 6, 7, 8, 9 or 10, the method comprises the following steps: heating rare earth oxide RE2O3 and excessive HX acid to react until the solution is clear and transparent, removing insoluble substances, filtering, washing, and drying to obtain the high-purity hydrated rare earth halide. A first mixed solution is obtained; evaporating and concentrating the first mixed solution, and filtering to obtain a hydrated rare earth halide crude product; dissolving the hydrated rare earth halide crude product in ethanol and heating to obtain a second mixed solution; and placing the second mixed solution in a reduced-pressure vacuum drying device, and removing ethanol and free water under reduced-pressure vacuum heating conditions to obtain a final product. By adopting the preparation method disclosed by the invention, the hydrated rare earth halide with high purity and fixed crystal water content can be obtained, the consumed time is short, and batch production is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of rare earth material preparation, and in particular to a preparation method and application of high-purity hydrated rare earth halide. Background Art

[0002] Rare earth elements have excellent magnetic, optical and electrical properties and have become important strategic elements. Hydrated rare earth halides are used in the liquid phase preparation of rare earth-doped laser fibers, organic synthesis catalyst precursors, organic rare earth complexes and other application fields, and have received widespread attention. For doping applications, the amount of rare earth ions is often trace doping, and slight differences in doping concentrations will have a significant impact on the product effects of downstream applications; for the application of complex precursors, the amount of rare earth ions needs to have a fixed molar ratio with the ligand, which is beneficial to improve the yield and purity. Therefore, it is necessary to accurately weigh the hydrated rare earth halides of a fixed ratio or weight. If the crystal water content of the hydrated rare earth halide is not fixed, it is difficult to accurately quantify the amount of hydrated rare earth halide by weight, which will result in poor batch consistency in the performance of downstream application products. Therefore, hydrated rare earth halides with a fixed crystal water content are the key to their downstream applications. The most common method for preparing hydrated rare earth halides is to directly dissolve rare earth oxides in hydrohalic acid. To remove free water on the surface, two methods are mainly used: heating and drying under inert gas and vacuum heating and drying. The following two methods have their own disadvantages as follows:

[0003] (1) Inert gas heating and drying: refers to heating and drying the supersaturated hydrated rare earth halide slurry under the protection of nitrogen or argon to remove excess free water. This method is simple to operate. If it is dried at a low temperature, it will take a long time, and the crystal water content of the obtained product will be unstable. Insufficient heating time will easily lead to incomplete removal of free water, and heating for too long will easily lead to the loss of some crystal water. If it is dried at a higher temperature, in addition to the loss of some crystal water, some hydrated rare earth halides will be easily hydrolyzed and oxidized to halogen oxides, reducing the purity of the product. In addition, if the single processing volume of this method is large, the slurry will easily harden during the inert gas heating and drying process, resulting in inconsistency between the amount of crystal water contained in the surface and internal hydrated rare earth halides.

[0004] (2) Vacuum heating and drying: refers to the process of heating and drying the supersaturated hydrated rare earth halide slurry at low temperature under negative pressure to remove excess free water. This method is simple to operate and usually needs to be carried out in a vacuum heating drying oven. However, due to the generation of acidic gas, it will seriously corrode and damage the experimental equipment, and introduce Fe impurities. This method is difficult to obtain high-purity hydrated rare earth halide. In addition, during the vacuuming process of this process, the slurry is prone to explosive boiling, causing the slurry to splash, pollute the vacuum heating drying oven, and seriously reduce the yield. Therefore, the cost of this process is relatively high. Summary of the invention

[0005] (I) Purpose of the invention

[0006] The purpose of the present invention is to provide a preparation method and application of high-purity hydrated rare earth halide. By adopting the preparation method of the present invention, hydrated rare earth halide with fixed crystalline water content can be obtained, and the time consumption is short, and the process is simpler and the cost is lower. It is easier to obtain hydrated rare earth halide with high purity and fixed crystalline water content, which is conducive to mass production.

[0007] (II) Technical solution

[0008] To solve the above problems, the first aspect of the present invention provides a method for preparing a high-purity hydrated rare earth halide, wherein the general formula of the hydrated rare earth halide is REX3·xH2O, wherein RE is a rare earth element, X is a halogen, and x is the amount of crystal water, and x is 6, 7, 8, 9 or 10. The method comprises the following steps:

[0009] S1, heating rare earth oxide RE2O3 and excess HX acid to react until the solution is clear and transparent, removing insoluble matter, and obtaining a first mixed solution;

[0010] S2, evaporating and concentrating the first mixed solution and filtering it to obtain a crude hydrated rare earth halide;

[0011] S3, dissolving the crude hydrated rare earth halide in ethanol and heating to obtain a second mixed solution;

[0012] S4, placing the second mixed solution in a reduced pressure vacuum drying device, removing ethanol and free water under reduced pressure vacuum heating conditions to obtain a REX3·xH2O product.

[0013] Furthermore, RE is selected from any one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y, and X is selected from any one of Cl, Br and I.

[0014] Furthermore, the pH of the first mixed solution in S1 is less than 7.

[0015] Furthermore, the heating temperature in S1 and S2 is controlled to be 80-200°C.

[0016] Furthermore, the evaporation concentration time in S2 is 4 to 48 hours.

[0017] Furthermore, the heating temperature in S3 is 45-150°C.

[0018] Furthermore, in S3, the molar ratio of ethanol to the rare earth oxide RE2O3 added in step S1 is 20 to 100:1.

[0019] Furthermore, the step S4 further comprises: connecting the air inlet of the reduced pressure vacuum drying device to the dried inert gas, and filling the reduced pressure vacuum device with the inert gas after the reduced pressure drying process is completed to obtain the REX3·xH2O product.

[0020] Furthermore, in the step S4, the heating temperature during the reduced pressure vacuum drying process is 40 to 150°C, and the vacuum degree is 10 - 1 Pa~10 -6 Pa.

[0021] In addition, the second aspect of the present invention provides an application of a hydrated rare earth halide, which can be used to prepare fluorescent materials, laser doping materials or rare earth complex precursors, and the hydrated rare earth halide is obtained according to any one of the methods for preparing high-purity hydrated rare earth halides described above.

[0022] (III) Beneficial effects

[0023] The above-mentioned technical scheme of the present invention has the following beneficial technical effects: the present invention adopts anhydrous ethanol to dissolve the crude hydrated rare earth halide for the second time, and the preparation method of rotary evaporation drying under negative pressure is used to prepare the hydrated rare earth halide, which can fix the crystal water content of the hydrated rare earth halide and completely remove the surface free water; in the present invention, the general formula of the hydrated rare earth halide is REX3·xH2O, x is the amount of crystal water, and x is 6, 7, 8, 9 or 10. During the preparation process, the crude hydrated rare earth halide is dissolved in ethanol and heated to obtain a second mixed solution; the second mixed solution is then placed in a reduced pressure vacuum drying device, and the REX3·xH2O product is obtained after removing ethanol and free water under reduced pressure vacuum heating conditions. The process design principle is as follows: the present invention adopts anhydrous ethanol to dissolve the crude hydrated rare earth halide for a second time, and then uses a rotary evaporation drying method under negative pressure to prepare the hydrated rare earth halide, which can successfully solve the problems existing in the existing process. Ethanol and water are mutually dissolved to form an azeotrope, and the boiling point is reduced to 78.1°C. The drying temperature is further reduced under reduced pressure conditions to improve the drying efficiency. Therefore, the hydrolysis of the halide can be inhibited while ensuring that the surface free water is completely removed during drying, thereby obtaining a hydrated rare earth halide with high purity and a fixed crystal water content. The obtained hydrated rare earth halide has a purer physical phase and better product consistency. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention is a preparation flow chart of a method for preparing high-purity hydrated rare earth halide. DETAILED DESCRIPTION

[0025] In order to make the purpose, technical scheme and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, the description of well-known structures and technologies is omitted to avoid unnecessary confusion of the concept of the present invention.

[0026] 1. Technical solution

[0027] like Figure 1 As shown, on the one hand, the present invention provides a method for preparing a high-purity hydrated rare earth halide, wherein the general formula of the hydrated rare earth halide is REX3·xH2O, wherein RE is a rare earth element, X is a halogen, and x is the amount of crystal water, and x is 6, 7, 8, 9 or 10, that is, the crystal water content is fixed to REX3·6H2O or REX3·7H2O, REX3·8H2O, REX3·9H2O or REX3·10H2O, and the purity of the prepared hydrated rare earth halide is ≥99.9%. To achieve the above purpose, the method for preparing a high-purity hydrated rare earth halide of the present invention includes the preparation of a hydrated rare earth halide crude product (including steps S1 and S2) and the drying of the hydrated rare earth halide (including steps S3 and S4), and the relevant reaction formula of step S1 is as follows:

[0028] 2RE2O3+6HX+(x-3)H2O=2REX3·xH2O; (1)

[0029] The preparation method of the present invention is specifically as follows:

[0030] S1, heating rare earth oxide RE2O3 and excess HX acid to react until the solution is clear and transparent, filtering to remove insoluble matter, and obtaining a first mixed solution; the reason for adding excess HX acid here is that rare earth halides have a large solubility and tend to be supersaturated when evaporated, and it is not suitable to precipitate pure hydrated rare earth halides by direct evaporation. Therefore, it is necessary to add excess HX acid to prepare a saturated solution to prevent hydrolysis;

[0031] S2, evaporating and concentrating the first mixed solution and filtering it to obtain a crude hydrated rare earth halide;

[0032] S3, dissolving the crude hydrated rare earth halide in ethanol and heating to obtain a second mixed solution;

[0033] S4, placing the second mixed solution in a reduced pressure vacuum drying device, removing ethanol and free water under reduced pressure vacuum heating conditions to obtain a REX3·xH2O product.

[0034] Furthermore, RE is selected from any one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y, and X is selected from any one of Cl, Br and I.

[0035] Furthermore, the pH of the first mixed solution in S1 is less than 7, and the prepared first mixed solution is an acidic solution, and the pH of the first mixed solution is still controlled to be less than 7 until the reaction is complete. The reaction heating temperature is 80 to 200° C., and more preferably 80 to 150° C. The filtering device uses filter paper or filter membrane, preferably slow filtration filter paper or polytetrafluoroethylene filter membrane.

[0036] Furthermore, step S2 specifically includes: heating the first mixed solution to evaporate and concentrate, stopping heating when solids precipitate on the surface of the liquid, and filtering to obtain a crude REX3 hydrate after cooling to room temperature. The reaction heating temperature is 80 to 200°C, more preferably 80 to 150°C. The heating evaporation concentration time is 4 to 48 hours, more preferably 4 to 36 hours. The filtering device uses filter paper or filter membrane, preferably slow filtration filter paper or polytetrafluoroethylene filter membrane.

[0037] Further, the step S3 specifically comprises: dissolving the crude hydrated rare earth halide obtained in step S2 (the crude hydrated rare earth halide is a wet solid crude product) in ethanol, and heating the solution to dissolve it to obtain a clear solution (i.e., the second mixed solution). The heating and dissolving temperature is 45 to 150° C., preferably 45 to 100° C., and more preferably 45 to 80° C. The molar ratio of ethanol to the rare earth oxide RE2O3 added in step S1 is 20 to 100:1, preferably 20 to 80:1; anhydrous ethanol (M = 46.07; ρ = 0.79 g / ml) can be used here to convert it into a volume amount; anhydrous ethanol is used here mainly to dissolve with the free water on the surface of the hydrated rare earth halide crude product to form a low-boiling azeotrope. The specific principle is: when the molar ratio of ethanol to the rare earth oxide RE2O3 added in step S1 is 20 to 100:1, the weight composition of ethanol and the residual free water on the surface of the crude product reaches about 95.6%wt, and the boiling point of the azeotrope formed at this time can be reduced to 78.1°C, so the drying temperature and drying time can be effectively reduced, and the probability of hydrolysis reaction during the drying process can be reduced, which is conducive to obtaining high-purity hydrated rare earth halides with a fixed crystal water content.

[0038] The S4 specifically includes: transferring the second mixed solution obtained in step S3 to a reduced pressure vacuum drying device, and removing free water and ethanol in the crude product by low-temperature heating under reduced pressure vacuum heating conditions to obtain a REX3·xH2O product. The air inlet in the reduced pressure vacuum drying device is connected to the dried inert gas, and after the hydrated rare earth halide drying process is completed, the reduced pressure vacuum drying device is filled with inert gas, and the inert atmosphere includes but is not limited to high-purity dry Ar gas or N2 gas. The reduced pressure vacuum drying device includes a vacuum heating drying oven coated with Teflon coating and a rotary evaporation device, preferably a rotary evaporation device. The heating temperature during the drying process is 40 to 150°C, preferably 40 to 100°C, and more preferably 45 to 80°C. The numerical range of the vacuum degree is 10 -1 Pa~10 -6 Pa; preferably 10 -1 Pa~10 -5 Pa, more preferably 10 -1 Pa~10 -3 Pa.

[0039] The following takes the preparation of hydrated ytterbium chloride (YbCl3·6H2O) commonly used in laser fiber doping as an example to illustrate the technical solution design of the present invention.

[0040] In the prior art, ytterbium chloride hydrate containing a large amount of free water is usually dried for a long time under inert gas to remove the surface free water to prepare ytterbium chloride hydrate with fixed crystal water. Although this method is simple to operate, it takes a long time if dried at low temperature, and the crystal water content of the obtained product is unstable. Insufficient heating time may cause incomplete removal of free water, and excessive heating may cause partial loss of crystal water. If dried at a higher temperature, in addition to the easy loss of some crystal water, some hydrated rare earth halides are easily hydrolyzed and oxidized to halogen oxides, reducing the purity of the product. In addition, if the single processing volume is large, the slurry is easy to harden during the inert gas heating and drying process, resulting in inconsistency in the amount of crystal water contained in the surface and internal hydrated rare earth halides.

[0041] In view of the problems existing in the inert gas heating and drying method, some studies have further adopted the vacuum heating and drying method. However, due to the generation of acidic gas, it will seriously corrode and damage the experimental equipment, and introduce Fe impurities, so it is difficult to obtain high-purity hydrated rare earth halides by this process. In addition, during the vacuuming process of this process, the slurry is prone to explosive boiling, causing the slurry to splash, pollute the vacuum heating drying box, and seriously reduce the yield. Therefore, the cost of this process is relatively high.

[0042] In view of the above shortcomings, the present application further studied and found that by using anhydrous ethanol to dissolve the crude ytterbium chloride hydrate twice, and then using a rotary evaporation drying method under negative pressure to prepare hydrated rare earth halides, the problems existing in the existing process can be successfully solved. Ethanol and water are mutually dissolved to form an azeotrope, and the boiling point is reduced to 78.1°C. The drying temperature is further reduced under reduced pressure to improve the drying efficiency. Therefore, it can inhibit the hydrolysis of the halide while ensuring that the surface free water is removed cleanly during drying, thereby obtaining a hydrated rare earth halide with high purity and a fixed crystal water content. In addition, the experimental equipment used in this method is made of quartz products and high borosilicate glass, which has good corrosion resistance, is easier to handle after the acidic tail gas is condensed, and has better environmental friendliness. This method is extended to the preparation of other similar hydrated rare earth halides that are prone to hydrolysis and oxidation, and they also have very similar beneficial effects.

[0043] In addition, another aspect of the present invention provides an application of a hydrated rare earth halide, which can be used to prepare a fluorescent material, a laser doping material or a rare earth complex precursor, and the hydrated rare earth halide is obtained according to any one of the methods for preparing a high-purity hydrated rare earth halide described in the above description. The hydrated rare earth halide can be used in fluorescent materials, laser doping materials or rare earth complex precursor materials. 2. Specific embodiments

[0045] Embodiment 1:

[0046] Preparation of hydrated lanthanum bromide: 50 g of 99.99% pure rare earth metal lanthanum oxide powder is dissolved in 142 ml of 47% HBr acid, stirred evenly, and placed on a heating plate, the heating temperature is set to 100° C., the heating time is 3 hours, after complete dissolution and the solution becomes clear, insoluble impurities are removed by filtering with slow filter paper, and the solution is continued to be placed on a heating plate for heating and concentration, the heating temperature is set to 150° C., the time is 12 hours, when solids are precipitated on the surface of the liquid, the heating is stopped, and after cooling to room temperature, it is filtered and the filtrate is discarded to obtain a crude hydrated lanthanum bromide. The crude lanthanum bromide hydrate (wet solid) was dissolved in 225 ml of anhydrous ethanol (the molar ratio of ethanol to rare earth oxide La2O3 was (100%×225×0.79 / 46.07):(50 / 325.809)≈25:1; the molecular weight of ethanol was 46.07, the density of anhydrous ethanol was 0.79 g / ml, and the molecular weight of lanthanum oxide was 325.809), and the mixed solution (the second mixed solution, the same for the subsequent embodiments) was set to a heating temperature of 70°C and heated until it was completely dissolved. At 8.3×10 -2Pa, 65 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain a LaBr3·7H2O product with a purity of 99.99%. This drying process takes 2 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0047] Embodiment 2:

[0048] Preparation of hydrated cerium bromide: Dissolve 50g of 99.99% pure rare earth metal cerium trioxide powder (cerium trioxide molecular weight is 328.24) in 141ml of 47% HBr acid, stir evenly, and place on a heating plate, set the heating temperature to 120°C, and heat for 6 hours. After the solution is completely dissolved and becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 150°C, and heat for 20 hours. When solid precipitates on the surface of the liquid, stop heating, and filter it after it cools to room temperature, discard the filtrate, and obtain hydrated cerium bromide crude product. Dissolve the wet solid (hydrated cerium bromide crude product) in 483ml of anhydrous ethanol (ethanol to rare earth oxide Ce2O3 molar ratio ≈ 55:1), set the mixed solution to a heating temperature of 60°C, and heat until it is completely dissolved. At 6.5×10 -2 Pa, 50 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain CeBr3·7H2O product with a purity of 99.99%. This drying process takes 3 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0049] Embodiment three:

[0050] Preparation of hydrated gadolinium bromide: Dissolve 50g of 99.99% pure rare earth metal gadolinium oxide powder (gadolinium oxide molecular weight is 362.50) in 128ml of 47% HBr acid, stir evenly, and place on a heating plate, set the heating temperature to 200°C, and heat for 4 hours. After the solution is completely dissolved and becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 200°C, and heat for 6 hours. When solid precipitates on the surface of the liquid, stop heating, and filter it after it cools to room temperature, discard the filtrate, and obtain crude hydrated gadolinium bromide. Dissolve the wet solid (crude hydrated gadolinium bromide) in 482ml of anhydrous ethanol (ethanol to rare earth oxide Gd2O3 molar ratio ≈ 60:1), set the mixed solution to a heating temperature of 80°C, and heat until it is completely dissolved. At 8.5×10 -2Pa, 55 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain a GdBr3·6H2O product with a purity of 99.99%. This drying process takes 2.5 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0051] Embodiment 4:

[0052] Preparation of lutetium bromide hydrate: Dissolve 50g of 99.99% pure rare earth metal lutetium oxide powder (molecular weight of lutetium oxide is 397.93) in 117ml of 47% HBr acid, stir evenly, and place on a heating plate. Set the heating temperature to 180°C for 6 hours. After the solution is completely dissolved and becomes clear, use slow filter paper to filter out insoluble impurities. Continue to place on a heating plate to heat and concentrate. Set the heating temperature to 150°C for 30 hours. When solid precipitates on the surface of the liquid, stop heating. After cooling to room temperature, filter it and discard the filtrate to obtain crude lutetium bromide hydrate. Dissolve the wet solid (crude lutetium bromide hydrate) in 560ml of anhydrous ethanol (molar ratio of ethanol to rare earth oxide Lu2O3 ≈ 70:1), set the mixed solution to a heating temperature of 68°C, and heat until it is completely dissolved. At 9.0×10 -2 Pa, 60 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain LuBr3·6H2O product with a purity of 99.99%, and this drying process takes 2 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0053] Embodiment five:

[0054] Preparation of hydrated scandium bromide: Dissolve 50g of rare earth metal scandium oxide powder with a purity of 99.95% (scandium oxide molecular weight is 137.91) in 335ml of 47% HBr acid, stir evenly, and place on a heating plate, set the heating temperature to 120°C, and heat for 4 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter out insoluble impurities, continue to place it on a heating plate for heating and concentration, set the heating temperature to 120°C, and the time is 18 hours. When solids precipitate on the surface of the liquid, stop heating, wait until it cools to room temperature, filter it, discard the filtrate, and obtain hydrated scandium bromide crude. Dissolve the wet solid (hydrated scandium bromide crude) in 530ml of anhydrous ethanol (ethanol to rare earth oxide Sc2O3 molar ratio ≈ 25:1), set the mixed solution to a heating temperature of 80°C, and heat until it is completely dissolved. At 7.5×10 -2Pa, 50 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain ScBr3·7H2O product with a purity of 99.95%. This drying process takes 3.5 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0055] Embodiment six:

[0056] Preparation of hydrated yttrium bromide: Dissolve 50g of 99.99% pure rare earth metal yttrium oxide powder (molecular weight of yttrium oxide is 225.81) in 205ml of 47% HBr acid, stir evenly, and place on a heating plate, set the heating temperature to 80°C, and heat for 6 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 150°C, and the time is 18 hours. When solid precipitates on the surface of the liquid, stop heating, and filter it after it cools to room temperature, discard the filtrate, and obtain hydrated yttrium bromide crude product. Dissolve the wet solid (hydrated yttrium bromide crude product) in 390ml of anhydrous ethanol (ethanol to rare earth oxide Y2O3 molar ratio ≈ 30:1), set the mixed solution to a heating temperature of 75°C, and heat until it is completely dissolved. At 3.5×10 -2 Pa, 45 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain a YBr3·8H2O product with a purity of 99.99%. This drying process takes 2.5 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0057] Embodiment seven:

[0058] Preparation of erbium chloride hydrate: Dissolve 50g of 99.99% pure rare earth metal erbium oxide powder (molecular weight of erbium oxide is 382.52) in 90ml 36% HCl acid, stir evenly, and place on a heating plate, set the heating temperature to 110°C, and heat for 5 hours. After the solution is completely dissolved and becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 120°C, and heat for 12 hours. When solid precipitates on the surface of the liquid, stop heating, and filter it after it cools to room temperature, discard the filtrate, and obtain crude erbium chloride hydrate. Dissolve the wet solid (crude erbium chloride hydrate) in 380ml anhydrous ethanol (ethanol to rare earth oxide Er2O3 molar ratio ≈ 50:1), set the mixed solution to a heating temperature of 73°C, and heat until it is completely dissolved. At 6.8×10 -2Pa, 50 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain ErCl3·6H2O product with a purity of 99.99%, and this drying process takes 3 hours. The dried inert gas is introduced into the rotary evaporator, and it is quickly transferred to an inert gas glove box, and the product is sealed and stored.

[0059] Embodiment eight:

[0060] Preparation of hydrated ytterbium chloride: Dissolve 50g of 99.99% pure rare earth metal ytterbium oxide powder (molecular weight of ytterbium oxide is 394.08) in 88ml 36% HCl acid, stir evenly, and place on a heating plate, set the heating temperature to 100°C, and heat for 4 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 120°C, and the time is 12 hours. When solid precipitates on the surface of the liquid, stop heating, wait until it cools to room temperature, filter it, discard the filtrate, and obtain hydrated ytterbium chloride crude. Dissolve the wet solid (hydrated ytterbium chloride crude) in 355ml anhydrous ethanol (ethanol to rare earth oxide Yb2O3 molar ratio ≈ 48:1), set the mixed solution to a heating temperature of 73°C, and heat until it is completely dissolved. At 8.6×10 -2 Pa, 58 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain a YbCl3·6H2O product with a purity of ≥99.9%. This drying process takes 3.5 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0061] Embodiment nine:

[0062] Preparation of gadolinium chloride hydrate: Dissolve 50g of 99.99% pure rare earth metal gadolinium oxide powder (gadolinium oxide molecular weight is 362.50) in 95ml 36% HCl acid, stir evenly, and place on a heating plate, set the heating temperature to 100°C, and heat for 3 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 100°C, and the time is 16 hours. When solid precipitates on the surface of the liquid, stop heating, wait until it cools to room temperature, filter, discard the filtrate, and obtain crude gadolinium chloride hydrate. Dissolve the wet solid (crude gadolinium chloride hydrate) in 320ml anhydrous ethanol (ethanol to rare earth oxide Gd2O3 molar ratio ≈ 40:1), set the mixed solution to 80°C, and heat until it is completely dissolved. At 9.8×10 -2Pa, 65 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain a GdCl3·6H2O product with a purity of 99.99%. This drying process takes 3 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0063] Embodiment ten:

[0064] Preparation of lutetium chloride hydrate: Dissolve 50g of 99.99% pure rare earth metal lutetium oxide powder (molecular weight of lutetium oxide is 397.93) in 87ml 36% HCl acid, stir evenly, and place on a heating plate, set the heating temperature to 100°C, and heat for 3 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter out insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 180°C, and heat for 12 hours. When solid precipitates on the surface of the liquid, stop heating, and filter it after it cools to room temperature, discard the filtrate, and obtain crude lutetium chloride hydrate. Dissolve the wet solid (crude lutetium chloride hydrate) in 330ml anhydrous ethanol (molar ratio of ethanol to rare earth oxide Lu2O3 ≈ 45:1), set the mixed solution to a heating temperature of 68°C, and heat until it is completely dissolved. At 7.4×10 -2 Pa, 55 ° C water bath heating, rotary evaporation to remove anhydrous ethanol and surface free water to obtain LuCl3·6H2O product with a purity of 99.99%, and this drying process takes 2.5 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0065] Embodiment eleven:

[0066] Preparation of hydrated europium iodide: Dissolve 50g of 99.95% pure rare earth metal europium oxide powder (molecular weight of lutetium oxide is 351.93) in 216ml 45% HI acid, stir evenly, and place on a heating plate, set the heating temperature to 130°C, and heat for 6 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 150°C, and heat for 12 hours. When solid precipitates on the surface of the liquid, stop heating, and filter it after it cools to room temperature, discard the filtrate, and obtain hydrated europium iodide crude product. Dissolve the wet solid (hydrated europium iodide crude product) in 207ml anhydrous ethanol (ethanol to rare earth oxide Eu2O3 molar ratio ≈ 25:1), set the mixed solution to a heating temperature of 65°C, and heat until it is completely dissolved. At 1.1×10 -1Pa, 75 ° C water bath heating by rotary evaporation to remove anhydrous ethanol and surface free water to obtain EuI3 · 9H2O product with a purity of 99.95%, this drying process takes 3 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to the inert gas glove box, and the product is sealed and stored.

[0067] Embodiment 12:

[0068] Preparation of lutetium iodide hydrate: Dissolve 50g of 99.95% pure rare earth metal lutetium oxide powder (molecular weight of lutetium oxide is 397.93) in 190ml 45% HI acid, stir evenly, and place on a heating plate, set the heating temperature to 100°C, and heat for 4 hours. After it is completely dissolved and the solution becomes clear, use slow filter paper to filter to remove insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 120°C, and heat for 30 hours. When solid precipitates on the surface of the liquid, stop heating, and filter the crude product after it cools to room temperature, discard the filtrate, and obtain lutetium iodide hydrate crude product. Dissolve the wet solid (lutetium iodide hydrate crude product) in 256ml anhydrous ethanol (ethanol to rare earth oxide Lu2O3 molar ratio ≈ 35:1), set the mixed solution to 75°C, and heat until it is completely dissolved. At 2.5×10 -1 Pa, 80 ° C water bath heating by rotary evaporation to remove anhydrous ethanol and surface free water to obtain LuI3 · 10H2O product with a purity of 99.95%, this drying process takes 3 hours. The dried inert gas is introduced into the rotary evaporator and quickly transferred to an inert gas glove box to seal and store the product.

[0069] Comparative Example 1:

[0070] Preparation of hydrated ytterbium chloride by inert gas heating and drying method: 50 g of rare earth metal ytterbium oxide powder with a purity of 99.99% was dissolved in 88 ml of 36% HCl acid, stirred evenly, and placed on a heating plate. The heating temperature was set to 100°C for 4 hours. After complete dissolution and the solution became clear, insoluble impurities were removed by filtering with slow filter paper. The solution was continued to be placed on a heating plate for heating and concentration. The heating temperature was set to 120°C for 12 hours. When solids precipitated on the surface of the liquid, the heating was stopped. After cooling to room temperature, the crude hydrated ytterbium chloride was filtered and the filtrate was discarded. The wet solid was placed in argon gas and heated and dried. The heating temperature was set to 100°C for 24 hours. After testing, the water content of the product was 30.26%, which was higher than the theoretical water content of 27.88% of the YbCl3·6H2O product; the heating temperature was set to 120°C for 24 hours. After testing, the water content of the product was 27.67%, which was close to the theoretical water content of 27.88% of the YbCl3·6H2O product; the heating temperature was set to 150°C for 24 hours. After testing, the water content of the product was 24.40%, which was lower than the theoretical water content of 27.88% of the YbCl3·6H2O product. Therefore, the inert gas heating and drying method takes a long time, and the hydrated ytterbium chloride obtained has an unstable crystalline water content, and is easy to lose some crystalline water during the heating process, making it difficult to obtain hydrated ytterbium chloride with a fixed crystalline water content.

[0071] Comparative Example 2:

[0072] Preparation of hydrated ytterbium chloride by vacuum heating and drying method: Dissolve 50g of 99.99% pure rare earth metal ytterbium oxide powder in 88ml 36% HCl acid, stir evenly, and place on a heating plate, set the heating temperature to 100°C, and heat for 4 hours. After the solution is completely dissolved and becomes clear, use slow filter paper to filter out insoluble impurities, continue to place on a heating plate to heat and concentrate, set the heating temperature to 120°C, and the time is 12 hours. When solids precipitate on the surface of the liquid, stop heating, wait until it cools to room temperature, filter the hydrated ytterbium chloride crude product, and discard the filtrate. Place the wet solid in a vacuum drying oven, and set the vacuum degree to 5.5×10 -2 Pa, the heating temperature was set to 100 ° C, the time was 24 hours, and the water content of the product was 32.30%, which was slightly higher than the theoretical water content of 27.88% of the YbCl3·6H2O product; the Fe impurity content in the obtained product was 2.53%, and obvious corrosion marks were visible on the surface of the vacuum oven. Therefore, the vacuum heating drying method will cause serious corrosion damage to the experimental device due to the generation of acidic gas, and introduce Fe impurities. This method is difficult to obtain high-purity hydrated ytterbium chloride, and the process cost is relatively high.

[0073] The product purity and crystal water content of the hydrated rare earth halides of Examples 1 to 12, Comparative Example 1 and Comparative Example 2 are shown in Table 1:

[0074] Table 1 Product purity and crystal water content information of hydrated rare earth halides

[0075]

[0076]

[0077] In summary, the above-mentioned embodiments of the present invention achieve the following technical effects: compared with the inert gas heating and drying method for preparing hydrated rare earth halides, the present invention can obtain hydrated rare earth halides with a fixed crystalline water content, and it takes less time, is easier to mass produce, and has good industrial application prospects; compared with the vacuum heating and drying method for preparing hydrated rare earth halides, the process of the present invention is simpler, the process cost is lower, and it is easier to obtain high-purity hydrated rare earth halides with a fixed crystalline water content, which is conducive to mass production.

[0078] The method for preparing high-purity hydrated rare earth halide provided by the present invention is simple and quick, and is a new method for preparing hydrated rare earth halide with high purity and fixed crystal water content. The purity of the prepared hydrated rare earth halide is ≥99.9%. The preparation method is simple to operate, low in cost, and has better environmental friendliness. The product prepared by the method of the present invention has the following advantages:

[0079] (1) Higher purity and significantly lower oxide impurity content;

[0080] (2) The crystal water content is more fixed, the crystal water content of batch-prepared products is more uniform, and the product consistency is significantly improved;

[0081] (3) The physical phase is purer, being a single-phase hydrated rare earth halide;

[0082] (4) It has greater cost advantages, is easier to mass-produce, and has good prospects for industrial application.

Claims

1. A method for preparing high-purity hydrated rare earth halide, characterized in that: The general formula of the hydrated rare earth halide is REX3·xH2O, wherein RE is a rare earth element, X is a halogen, x is the amount of crystal water, and x is 6, 7, 8, 9 or 10. The method comprises the following steps: S1, heating rare earth oxide RE2O3 and excess HX acid to react until the solution is clear and transparent, removing insoluble matter, and obtaining a first mixed solution; S2, evaporating and concentrating the first mixed solution and filtering it to obtain a crude hydrated rare earth halide; S3, dissolving the crude hydrated rare earth halide in ethanol and heating to obtain a second mixed solution; S4, placing the second mixed solution in a reduced pressure vacuum drying device, removing ethanol and free water under reduced pressure vacuum heating conditions to obtain a REX3·xH2O product.

2. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: The RE is selected from any one of La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Sc and Y, and the X is selected from any one of Cl, Br and I.

3. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: The pH of the first mixed solution in S1 is less than 7.

4. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: The heating temperature in S1 and S2 is controlled to be 80-200°C.

5. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: The evaporation concentration time in S2 is 4 to 48 hours.

6. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: The heating temperature in S3 is 45-150°C.

7. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: In the step S3, the molar ratio of ethanol to the rare earth oxide RE2O3 added in the step S1 is 20 to 100:

1.

8. The method for preparing high-purity hydrated rare earth halide according to claim 1, characterized in that: The step S4 further comprises: connecting the air inlet of the reduced pressure vacuum drying device to the dried inert gas, and filling the reduced pressure vacuum device with the inert gas after the reduced pressure drying process is completed to obtain the REX3·xH2O product.

9. The method for preparing high-purity hydrated rare earth halide according to claim 8, characterized in that: In the step S4, the heating temperature during the reduced pressure vacuum drying process is 40 to 150°C, and the vacuum degree is 10 -1 Pa~10 -6 Pa.

10. An application of a hydrated rare earth halide, characterized in that: The hydrated rare earth halide can be used to prepare fluorescent materials, laser doping materials or rare earth complex precursors, and the hydrated rare earth halide is obtained according to the method for preparing high-purity hydrated rare earth halide according to any one of claims 1-9.

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