WO2019168420A1

WO2019168420A1 - Method for manufacturing of inorganic salts with monovalent cation and anion of transition metal acid, in particular in the form of micro- and nanocrystals

Info

Publication number: WO2019168420A1
Application number: PCT/PL2019/000009
Authority: WO
Inventors: Marta PRZESNIAK-WELENC; Kamila ZELECHOWSKA
Original assignee: Politechnika Gdanska
Priority date: 2018-03-01
Filing date: 2019-01-28
Publication date: 2019-09-06

Abstract

Invention relates to a method for manufactming of inorganic salt of general formula A_xM_yO_z, where A: NH₄ ⁺ or K⁺ or Rb⁺ or Cs⁺; M: Mo or V, O: oxygen, comprising precipitation of solids from molybdenum trioxide or vanadium pentoxide solution by potassium or rabidium or cesium or ammonium salt. According to the invention, the used salt is at least one organic salt of potassium or rabidium or cesium or ammonium. The salt is being dissolved in at least one solvent and the obtained solution is being mixed with molybdenum trioxide or vanadium pentoxide, keeping the weight ratio of potassium or rubidium or cesium or ammonium salt to molybdenum trioxide or vanadium pentoxide as at least 1:1.

Description

Method for manufacturing of inorganic salts with monovalent cation and anion of transition metal acid, in particular in the form of micro- and nanocrystals

The invention relates to a method of preparation of inorganic salts comprising monovalent cation and anion of transition metal acids such as vanadates and molybdates of general structure A_xM_yO_z, where A: NH₄ ⁺ or K⁺ or Rb⁺ or Cs⁺; M: V or Mo or O: oxygen, wherein the salts are in particular in the form of micro- and nanocrystals.

The invention relates to the method of manufacturing of compounds such ammonium molybdates or potassium molybdates or rubidium molybdates or cesium molybdates and ammonium vanadates or potassium or rubidium vanadates or cesium vanadates.

Vanadates are vanadic(V) acids salts. In particular, alkali metal and ammonium metavanadates are industrially used. Potassium metavanadate, KVO3 is used as a catalyst, coiTOsion inhibitor, anti-lime agent and in chemical synthesis, among others in crude oil processing.

RbVCb and CsVCb are studied as potential materials for optoelectronic devices, as for example LEDs. Ammonium metavanadate with formula of NH₄VO₃, is an inorganic compound well soluble in hot water and diluted ammonium hydroxide. It is a white or yellowish solid. Ammonium metavanadate plays an important role in vanadium oxides manufacturing (as V₂O₅) and some other chemical, e.g. luminescent materials. NH₄VO₃ calcined in 500-550°C gives V₂0₅ of the highest purity. It is also used in dye industry, in varnishes and indelible inks production, or as a moisture absorber for paints and inks. Recently, compounds as NH₄V₃O₈ (anhydrous and hydrates), (NH4)₂V30₈ and NH₄V₄O₁0 have gained much attention as they reveal desired properties for lithium-ion and sodium- ion batteries. In the production process of the compounds mentioned above, ammonium metavanadate is used as a precursor. The purity and size of the particles of NH₄VO₃ determine the properties of obtained materials.

Molybdates, the molybdic(VI) acid salts, with formula M₂Mo0₄ (where M - NH₄ ⁺ or alkali metals) are used in the pigments production and as fertilizer, being a source of molybdenum - one of the essential micronutrients. Ammonium molybdate is used in catalysts manufacturing, in analytical chemistry, and in phosphomolybdic acid production, which is used in the production of catalysts, as thin layer chromatography reagent and staining agent in histopathological tests. Molybdates are also used in the ceramics.

Therefore, methods of vanadates and molybdates production, in particular in the form of controllable size and shape of particles, are of great importance for the industrial usage and for the development of chemistry of such compounds.

Ammonium metavanadate is normally prepared in an elaborate chemical process, which generates high cost. In publication by G. Brauer "Ammonium Metavanadate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1272 the method of NH4VO3 preparation was disclosed, where treating NaV0₃ aqueous solution with ammonium chloride caused ammonium metavanadate precipitation. However, NaV03 is obtained in a complicated, multi-step process. Firstly, V2O5 and Na₂C03 solution is boiled until complete release of C0₂ occurs, followed by addition of KMn0₄. The formed, insoluble by-products (V₂0₅ and Mn0₂) are removed by suction filtration and H₂0₂ is added into the clear supernatant. Such mixture is heated up to 60°C and then it is poured into the boiling aqueous NH4CI. The solution is left for several hours for NH4VO3 precipitation. The white or nearly white solid is filtered and washed to obtain NH4VO3 contaminated with V₂0₅ and sodium and potassium cations. In order to obtain high purity material, the procedure described above is repeated several times. The yield of one sequence is 80%. The reaction between KM11O4 and H₂0₂ is vigorous and requires special security practices, which is a key disadvantage of the process.

US3063795 discloses a method of production of pure ammonium metavanadate directly from acidic solvent extraction strip solutions in a single precipitation step. In the method, vanadyl solution is formed containing impurities such as alumina oxide, phosphates, arsenates with addition of sodium chlorate at least sufficient to oxidize the vanadium. Then, the solution of sodium carbonate and ammonia is added. The solution is stirred at 80-85°C for impurities precipitation which is then filtered off. In the next step, sufficient ammonium chloride is added to precipitate the ammonium metavanadate. The described method requires the use of elevated temperature and an oxidant harmful to the health and the environment.

US365381 discloses a method of preparation of pure ammonium metavanadate from contaminated NH4VO3 solution.. In the method contaminated NH4VO3 solution of pH 9 is kept at 90-95°C. The precipitation of pure ammonium metavanadate is accomplished by cooling down the mixture to 16°C. The disadvantage of the method is the need of energy consuming heating and cooling down the reaction mixture.

The method of ammonium metavanadate production described in CN 104973626 consists of mixing polyvinyl alcohol and soluble ammonium inorganic salts (as ammonium chloride, ammonium nitrate(V), ammonium carbonate) with sodium vanadate solution. Solids are separated at 40-60°C. The usage of expensive polyvinyl alcohol significantly increases costs of the production.

In CN 103420416 the method of ammonium metvanadate is disclosed. In method, ammonium metavanadate is precipitated from vanadium(V) solution by inorganic ammonium salt as ammonium sulphate(VI), ammonium chloride, ammonium nitrate(V), or the mixture of thereof. Described process is carried out at 60-90°C. The key disadvantage is requirement of heating the reaction mixture.

Many protocols for ammonium metavanadate precipitation using inorganic ammonium salts are known. In C 104058456 ammonium oxalate is used in NH₄VO₃ synthesis. Vanadium(V) solution of pH>7, kept at the temperature between 25-80°C is treated with ammonium oxalate. For ammonium metavanadate precipitation the usage of low-molecular mass alcohol, e.g. methanol, ethanol, propanol, butanol is required. The key disadvantage of the approach is requirement of heating, and pH controlling, and usage of alcohols for ammonium metavanadate precipitation.

Boiling of V2O5 with concentrated KOH solution is a known method of KVO3 preparation, described by McGraw-Hill in Inorganic synthesis, 1974. As a result, number of hydrates is formed (2KV0₃-3H₂0; KV0₃.2H₂0; 2KV0₃.5H₂0; KV0₃-3H₂0), which release water while heated, giving anhydrous KV0₃. Similarly, KV0₃ can be obtained by heating of K₂C0₃ and V₂05 solution for 2-3 h at 90°C. The key disadvantage of this approach is requirement of multiplicity of purification steps and intense foaming during heating. Alternate approach of method is disclosed in publication Trypuc, Ind. Eng. Chem. Res. 2001, 40, 1022-1025. It describes preparation of KV0₃ in the reaction of solid KC1 and V2O5 in the presence of steam or oxygen. HC1 and Cl₂ are formed as by-products, when steam or oxygen is used, respectively, which is the key disadvantage of the process. RbV0₃ and CsV0₃ can be obtained by grinding of Rb₂C0₃ or Cs₂C0₃ with V₂05, followed by calcination at 400-600°C for 12-24 h. High crystallinity of the material is obtained by re-grinding and further calcining for 24 h. [Muller, Journal of Solid State Chemistry 156, 379-389 (2001); Jin, Res Chem Intermed.] The key disadvantage of this approach is requirement of high temperature calcining.

The method of KV0₃ production also is disclosed in CN105236483. According to the method, aqueous solution of potassium carbonate, potassium bicarbonate or potassium hydroxide with ammonium metavanadate is heated in the microwave reactor for 15-30 min at temperature of 50-70°C. The advantage of this method is a short time and moderate temperature, however it requires specialized equipment and therefore, the possibility of the large scale production is limited.

Molybdic acid salts are obtained in similar reactions as described above. Materials and Technology, Longmans, Green and Co Ltd. J.H. de Bussy, 1968, Amsterdam oraz Comprehensive Inorganic Chemistry, Pergamon Press 1975, UK, Oxford. R.J.H. Clark (vanadium); C.L. Rollinson (Molibdenium) discloses the method of molybdates preparation. The compounds of general formula M2M0O4 or M₂Mo0₄ xH₂0, where M - alkali metals, can be obtained in the sintering process of Mo0₃ with adequate carbonate or oxide of alkali metals. The key disadvantage is requirements of high temperature required for melting of solid compounds. In the second approach, Mo0₃ is reacted with lye MOH, where M - alkali metals. The disadvantage is the usage of caustic alkali metal hydroxides. Sintering of CsCl and Ag₂Mo0₄ is also known as a method of Cs₂Mo0₄ manufacturing.

In publication H. Shigematsu Ferroelectrics 414 (2011) 195-200 the method of Rb₂Mo0₄ preparation is disclosed. Powdered Rb₂C0₃ and Mo0₃ are heated in air at 627°C for 24 h. In the second approach disclosed in this paper, the solution of Rb₂C0₃ and Mo0₃ in the concentrated ammonia is heated to solvent evaporation, followed by calcination for 4 h at 227°C. In both protocols, the key disadvantage is the need of calcining. New methods of vanadates and molybdates manufacturing are required that enable to eliminate disadvantages of known methodology, in particular method enables micro- or nanostructure in expected foi and structure to be obtained.

The invention provides an improved process for preparing compounds of general formula A_xM_yO_z, where A: NH₄ ⁺, K⁺, Rb⁺, Cs⁺; M: V or Mo and O: oxygen, preferably compounds in the form of micro- and nanocrystals.

Unexpectedly, it has been shown that addition of organic salt of the monovalent cations of the product eliminates the disadvantages of known approaches. It was surprisingly found out, that addition of organic salts of ammonium, potassium, rubidium or cesium, in particular formates or acetates, precipitates the respective vanadates or molybdates in a crystal form at room temperature, without requirements of stirring. Type of the organic salt and the solvent affects the vanadate or molybdate structure.

The method according to the invention involves mixing of respective oxide M0O3 or V O with aqueous or non-aqueous solution of organic salt of ammonium, potassium, rubidium or cesium, preferably ammonium, potassium, rubidium or cesium formate or acetate.

The present invention provides a method for preparing molybdates of general formula A_xM_yO_z, where A: NH⁴⁺ or K⁺ or Rb⁺ or Cs⁺; M: Mo and O: oxygen. In one embodiment, as potassium or rubidium or cesium or ammonium salt at least one organic potassium or rubidium or cesium or ammonium salt is used, which is dissolved in at least one solvent. In an embodiment, the resulting solution is mixed with molybdenum trioxide, keeping the weight ratio of the potassium or rubidium or cesium or ammonium salt or the mixture of thereof to molybdenum trioxide at least 1: 1. Then the resulting solution is left to precipitate molybdate. Preferably, an excess of organic salt is used.

The present invention provides a method for preparing vanadates of general formula A_xM_yO_z, where A: NH⁴⁺ or K⁺ or Rb⁺ or Cs⁺; M: V and O: oxygen. In an embodiment, as potassium or rubidium or cesium or ammonium salt at least one organic potassium or rubidium or cesium or ammonium salt is used, which is dissolved in at least one solvent. In an embodiment, the resulting solution is mixed with vanadium pentoxide, keeping the weight ratio of the potassium or rubidium or cesium or ammonium salt or the mixture of thereof to vanadium pentoxide at least 1 : 1. Then the resulting solution is left to precipitate vanadate. Preferably, an excess of organic salt is used.

In preferred embodiment, water and/or organic solvent is used.

In preferred embodiment, the ratio of potassium, rubidium, cesium or ammonium salt to vanadium pentoxide or molybdenum trioxide is 1 : 1 to 200: 1 (w/w).

In preferred embodiment, the nanocrystal form of vanadium pentoxide or molybdenum trioxide is advantageously used.

In preferred embodiment, ammonium, potassium, rubidium or cesium formate or acetate is advantageously used.

In preferred embodiment, precipitation occurs at room temperature up to the boiling points of the solvents or the mixture of thereof.

In preferred embodiment, an excess of organic salt to vanadate pentoxide or molybdenum trioxide is used, whereas to the supernatant obtained after precipitation of vanadates or molybdates, containing the organic salt of ammonium, rubidium, potassium or cesium, vanadium pentoxide or molybdenum trioxide is added, keeping the ratio of salt to vanadium pentoxide or molybdenum oxide at least 1 :1.

The advantages of the method according to the invention are: a one-step course of the manufacturing; running the method at room temperature, in contrast to known methods, which consist of melting salts and oxides carried out at temperature of several hundred Celsius degrees; no requirements of stilling during the reaction; no need of pH control; the ability to control the morphology of the obtained structures by changing reaction parameters; the possibility of using the obtained supernatant in the next synthesis.

The following examples further and the accompanying drawing disclose the embodiments of the invention, , in which following are disclosed: fig.1 - diffractogram of CsV₃0₈ obtained as described in Example 1, fig.2 - diffractogram of Cs₂V₄0n obtained as described in Example 2, fig 3 - SEM image of CS₂V₄O₁₁ crystals obtained as described in Example 4, fig.4- SEM image of CS₂V₄O₁₁ crystals obtained as described in Example 6, fig. 5- diffractogram of CS₂V₄O₁₁ obtained as described in Example 7, fig. 6 - diffractogram of Cs₂Mo₃Oio H₂0 obtained as described in Example 13, fig. 7 - SEM image of CS₂M0₉O₂₈ crystals obtained as described in Example 16, fig.8 - diffractogram of RbV0₃ obtained as described in Example 19, fig. 9 - SEM image of RbV0₃ crystals obtained as described in Example 22, fig. 10 - SEM image of RbV₃0₈ crystals obtained as described in Example 23, fig. 11 - SEM image of RbV₃0₈ ciystals obtained as described in Example 25, fig. 12 - diffractogram of Rb₂Mo₃0io-H₂0 obtained as described in Example 27, fig. 13- diffractogram of KV0₃ obtained as described in Example 33, fig. 14 - diffractogram of K₂(MO₃O_IO)-(H₂0)₃ obtained as described in Example 43, fig. 15 - diffractogram of (NH₄)₆(MO₇0₂₄) (H20)₄ obtained as described in Example 51, fig. 16 - diffractogram of ammonium metavanadate obtained as described in Example 59, fig. 17 - SEM image of NH₄V0₃ microcrystals obtained as described in Example 59, fig. 18 - FTIR spectrum of NH₄V0₃ obtained as described in Example 62, fig. 19 - SEM image of NH₄V0₃ microcrystals obtained as described in Example 62, fig. 20 - SEM image of NH₄V0₃ nanocrystals obtained as described in Example 64, fig. 21 - confocal microscope image of NH₄V0₃ obtained as described in Example 67, fig. 22 - SEM image of NH₄V0₃ microcrystals obtained as described in Example 72, fig. 23 - SEM image of NH₄V0₃ microcrystals obtained as described in Example 73, fig. 24 - SEM image of NH₄V0₃ nanocrystals obtained as described in Example 74, fig. 25 - SEM image of NH₄V0₃ microcrystals obtained as described in Example 75

Example 1

Preparation of cesium vanadate

Cesium formate (0.5 g) is dissolved in 20 mL of water and 200 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added. The solution is mixed at room temperature for complete dissolution of vanadium pentoxide. Ultrasonication speeds up the process. The reaction is earned out at room temperature, up to the boiling point of the solvent. Yellowish precipitate of CsV₃0₈ is formed. Diffractogram presented in fig. 1 confirms its crystal structure.

Example 2

Preparation of cesium vanadate

Cesium formate (0.5 g) is dissolved in 20 mL of formamide and 200 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of salt to oxide as 10:4. The solution is mixed at room temperature for several minutes. Ultrasonication speeds up the process. The reaction is carried out at room temperature, up to the boiling point of the solvent. Yellowish precipitate of CS₂V₄O₁₁ is formed. Diffractogram presented in fig. 2 confirms its crystal structure.

Example 3

The procedure is similar as in Example 2, with the exception that cesium formate to vanadium pentoxide ratio is 1 : 1 (w/w).

Example 4

Preparation of cesium vanadate

Cesium formate (1 g) is dissolved in 20 mL of water and 100 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added. The solution is mixed at room temperature for complete dissolution of vanadium pentoxide. After 24 h yellowish precipitate of CS₂V₄O₁₁ is collected by known methods. Fig. 3 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 4, Cs₂V₄0i ₁ microcrystals not bigger than 50 pm can be prepared. Example 5

The procedure is similar as in Example 4, with the exception that cesium formate to vanadium pentoxide ratio is 1 : 1 (w/w).

Example 6

Preparation of cesium vanadate

Cesium formate (1 g) is dissolved in 20 mL of formamide and 100 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the cesium formate to vanadium pentoxide ratio as 10:1. The solution is stirred at room temperature for several minutes and left for 24 h. Yellowish precipitate of CS₂V₄O₁₁ is collected by known methods. Fig. 4 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 6, CS₂V₄O₁₁ microcfystals not bigger than 3 pm can be prepared.

Example 7

Preparation of cesium vanadate

Cesium formate (2.7 g) is dissolved in 20 mL of form amide and 1 g of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the cesium formate to vanadium pentoxide ratio as 27: 10. The solution is stirred at room temperature for several minutes. Ultrasonication speeds up the process. Yellowish precipitate of CS₂V₄O₁₁ is collected by known methods. Fig. 5 presents ciystal structure of obtained material.

Example 8

Preparation of cesium vanadate

To 50 mg of commercially available vanadium pentoxide 20 mL of supernatant obtained in the procedure descibed in Example 6 is added, keeping the weight ratio of cesium formate to vanadium pentoxide as at least 1 :1. The solution is left to precipitate solid CS₂V₄O₁₁. The collected product is dried overnight at vacuum dryer at RT. Example 9

Preparation of cesium vanadate

To 20 mL of 3% mol. solution of cesium formate 1 g of commercially available vanadium pentoxide is added, keeping the weight ratio of cesium formate to vanadium pentoxide as 60:1. The solution is stirred for several minutes. The precipitated CS₂V₄O₁₁ is collected and dried.

Example 10

The procedure is similar as in Example 6, with the exception that 1 g of nanostmctural V2O5 is used, which can be obtained by known procedure. Nanostmctural V2O5 is obtained in sol-gel method by mixing 1.5 mL of vanadium(V) oxytripropoxide and 10 mL of anhydrous ethanol and 0.5 pL of acetyl acetone. The obtained sol is dried at 50°C to obtain xerogel. The xerogel is calcined at 600-650°C in oxidative atmosphere, giving 1 g of nanostmctural V2O5.

Example 11

Preparation of cesium vanadate

In 50 mL of formamide and deionized water in volume ratio as 4:1, 2.7 g of cesium formate is dissolved and 1 g of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of cesium formate to vanadium pentoxide as 27:10. The solutionis stirred for several minutes. Ultrasonication speeds up the process. Yellowish solid of CS₂V₄O₁₁ is obtained, which is dried in vacuum dryer overnight at rt.

Example 12

The procedure is similar as in Example 11, with the exception that 1 g of nanostmctural V2O5 is used, which can be obtained by known procedure.

Example 13

Preparation of cesium molybdate

1 g of cesium formate is dissolved in 20 mL of deionized water and 100 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of cesium formate to molybdenum trioxide as 10: 1. Solution is stirred for several minutes at RT. Ultrasonication speeds up the reaction. The yellowish solid CS₂MO₃O_IO-H₂0 is obtained. Diffractogram presented in fig. 6 confirms its ciystal structure.

Example 14

The procedure is similar as in Example 13, with the exception that cesium formate to molybdenum trioxide ratio is 1 : 1 (w/w).

Example 15

Preparation of cesium molybdate

To 50 mg of commercially available molybdenum trioxide 20 mL of supernatant obtained in the procedure descibed in Example 13 is added, keeping the weight ratio of cesium formate to molybdenum trioxide at least 1 :1. The solution is left to precipitate solid CS₂M0₃O₁₀ H₂O. The collected product is dried overnight at vacuum dryer at RT.

Example 16

Preparation of cesium molybdate

1.16 g of cesium formate is dissolved in 50 mL of 2-propanol and 100 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of cesium formate to molybdenum trioxide as 1 16:10. Solution is stirred for several minutes at RT. Ultrasonication speeds up the reaction. The reaction is carried out at room temperature, up to the boiling point of the solvent. The yellowish solid CS₂M0₉O₂₈ is obtained. SEM image presented in fig. 7 confirms, that by method described in Example 16 elongated CS₂M0₉O₂₈ microcrystals are obtained.

Example 17

The procedure is similar as in Example 16, with the exception that cesium formate to molybdenum trioxide ratio is 1 : 1 (w/w). Example 18

Preparation of cesium molybdate

0.5 g of cesium formate is dissolved in 20 mL of 1 -propanol and 100 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of cesium formate to molybdenum trioxide as 10:4. Solution is stirred for several minutes at RT. Ultrasonication speeds up the reaction. The reaction is carried out at room temperature, up to the boiling point of the solvent. The yellowish solid CS2M09O28 is obtained, which is dried overnight in the vacuum diyer at RT.

Example 19

Preparation of rubidium vanadate

2 g of rubidium formate is dissolved in 20 mL of formamide and 500 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the rubidium formate to vanadium pentoxide ratio as 4: 1. The solution is mixed at room temperature for several minutes, and solid RbV0₃ is collected by known methods. Diffractogram presented at fig. 8 confirms the crystal structure of the obtained material.

Example 20

The procedure is similar as in Example 19, with the exception that rubidium formate to vanadium pentoxide ratio is 1: 1 (w/w).

Example 21

The procedure is similar as in Example 19, with the exception that 500 mg of

nanostmctural V2O5 is used, which can be obtained by known procedure.

Example 22

Preparation o rubidium vanadate

To 200 mg of commercially available vanadium pentoxide 20 mL of supernatant obtained in the procedure described in Example 19 is added, keeping the weight ratio of rubidium formate to vanadium pentoxide at least 1 : 1. The solution is left to precipitate solid RbV0₃. The collected product is dried overnight at vacuum dryer at RT. The SEM image, presented in fig. 9 conforms, that by method described in Example 22, RbV0 nanoplateles are obtained.

Example 23

Preparation o rubidium vanadate

To 20 mL of 1.5% mol. aqueous solution of rubidium formate 500 mg of commercially available vanadium pentoxide is added, keeping the weight ratio of rubidium formate to vanadium pentoxide as 4:1. The solution is stirred for several minutes. The precipitated RbV 0 is collected and dried. Diffractogram presented in fig. 10 confirms the ciystal structure of obtained material.

Example 24

The procedure is similar as in Example 23, with the exception that rubidium formate to vanadium pentoxide ratio is (w/w).

Example 25

The procedure is similar as in Example 23, with the exception that 500 mg of nano structural V O is used, which can be obtained by known procedure, keeping the mass ratio of rubidium fomiate to vanadium pentoxide as 4: 1. SEM image presented in fig. 11 confirms, that by method described in Example 25, nanosheets of RbV₃0₈ are obtained.

Example 26

Prepartion of rubidium vanadate

In 50 mL of formamide and deionized water in volume ratio as 3:2, 3 g of rubidium formate is dissolved and 1 g of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of rubidium formate to vanadium pentoxide as 3:1. The solution is stirred for several minutes at RT. The solid RbV₃Og is obtained, which is dried in vacuum dryer overnight at rt. Example 27

Preparation of rubidium molybdate

To 20 mL of 1.5% mol. aqueous solution of rubidium formate 500 mg of commercially available molybdenum trioxide is added, keeping the weight ratio of rubidium fonnate to molybdenum trioxide as 4: 1. The solution is stiixed for several minutes. The precipitated Rb₂Mo₃Oi₀-H₂O is collected and dried. Diffractogram presented in fig. 12 confirms the crystal structure of the obtained material.

Example 28

The procedure is similar as in Example 27, with the exception that rubidium formate to molybdenum trioxde ratio is 1 :1 (w/w).

Example 29

Preparation of rubidium molybdate

To 100 mg of commercially available molybdenum tioxide 20 mL of supernatant obtained in the procedure described in Example 27 is added, keeping the weight ratio of rubidium formate to molybdenum trioxide at least 1 : 1. The solution is left at RT to precipitate solid RbiMoaOio fEO. The collected product is dried overnight at vacuum dryer at RT.

Example 30

Preparation of rubidium molybdate

0.5 g of rubidium formate is dissolved in 50 mL of 2-propanol and 0.5 g of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of rubidium formate to molybdenum trioxide as 1 : 1 Solution is stirred for several minutes at RT. The reaction is carried out at room temperature, up to the boiling point of the solvent. The yellowish solid Rb₂Mo₃Oio is obtained, which is dried overnight at RT in a vacuum dryer.

Example 31

The procedure is similar as in Example 30, with the exception that rubidium formate to molybdenum trioxde ratio is 1 : 1 (w/w). Example 32

Preparation of rubidium molybdate

1 g of rubidium formate is dissolved in 20 mL of 1 -propanol and 200 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of cesium formate to molybdenum trioxide as 10:2. Solution is stirred for several minutes at RT. The reaction is carried out at room temperature, up to the boiling point of the solvent. The yellowish solid Rb₂Mo₃Oi₀ is obtained, which is dried overnight in the vacuum dryer at RT.

Example 33

Preparation of potassium vanadate

To 20 mL of 3% mol. aqueous solution of potassium acetate 200 mg of commercially available vanadium pentoxide is added, keeping the weight ratio of potassium acetate to vanadium pentoxide as 15:1. The solution is stirred for several minutes. The reaction is earned out at room temperature, up to the boiling point of the solvent. The white solid KVO3 is collected and dried overnight at RT in vacuum dryer. Diffractogram presented in fig. 13 confirms the crystal structure of obtained material.

Example 34

Preparation of potassium vanadate

To 200 mg of commercially available vanadium pentoxide 20 mL of supernatant obtained in the procedure described in Example 33 is added, keeping the weight ratio of potassium acetate to vanadium pentoxide at least 1: 1. The solution is left to precipitate solid KV0₃. The collected product is dried overnight at vacuum dryer at RT.

Example 35

The procedure is similar as in Example 33, with the exception that potassium acetate to vanadium pentoxide ratio is 1 : 1 (w/w). Example 36

The procedure is similar as in Example 33, with the exception that 200 mg of

nanostmctural V O is used, which can be obtained by known procedure, keeping the weight ratio of potassium acetate to vanadium pentoxide as 15:1.

Example 37

Preparation of potassium vanadate

To 50 mL of 5% mol. aqueous solution of potassium formate 1 g of commercially available vanadium pentoxide is added, keeping the weight ratio of potassium formate to vanadium pentoxide as 12:1. The solution is stirred for several minutes. The reaction is earned out at room temperature, up to the boiling point of the solvent. The white solid KVO₃ is collected and dried overnight at RT in vacuum dryer.

Example 38

The procedure is similar as in Example 37, with the exception that potassium formate to vanadium pentoxide ratio is (w/w).

Example 39

Preparation of potassium vanadate

2 g of potassium acetate and 1 g of potassium formate is dissolved in 25 mL of water, then 500 mg of commercially available vanadium pentoxide is added, keeping the weight ratio of potassium acetate and potassium formate to vanadium pentoxide as 6: 1. The solution is stirred, and left overnight at 40-65°C to precipitate KV0₃. The collected solid is dried at RT.

Example 40

Preparation of potassium vanadate

3 g of potassium acetate is dissolved in 50 mL of formamide and 1 g of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the potassium acetate to vanadium pentoxide ratio as 3: 1. The solution is mixed at room temperature for several minutes, and white solid KVO3 is collected by known methods. Ultrasonication speeds up the process.

Example 41

Preparation of potassium vanadate

To 500 mg of commercially available vanadium pentoxide 50 mL of supernatant obtained in the procedure descibed in Example 40 is added, keeping the weight ratio of potassium acetate to vanadium pentoxide at least 1 : 1. The solution is left to precipitate solid KV0₃. The collected product is dried overnight at vacuum dryer at RT.

Example 42

The procedure is similar as in Example 40, with the exception that potassium acetate to

Example 43

Preparation of potassium molybdate

To 50 mL of 5% mol. aqueous solution of potassium formate 1 g of commercially available molybdenum trioxide is added, keeping the weight ratio of potassium formate to molybdenum trioxide as 12: 1. The solution is stirred for several minutes at RT. The white solid K₂(MO₃O_IO)-(H₂0)₃ is collected and dried overnight at RT in vacuum dryer. Diffractogram presented in fig. 14 confirms the crystal structure of the material.

Example 44

The procedure is similar as in Example 43, with the exception that potassium formate to molybdenum trioxide ratio is 1 : 1 (w/w).

Example 45

Preparation of potassium molybdate

To 500 mg of commercially available molybdenum trioxide 20 mL of supernatant obtained in the procedure descibed in Example 43 is added, keeping the weight ratio of potassium formate to molybdenum trioxide at least 1:1. The solution is left to precipitate solid K₂(Mq₃qio)·(H₂0)₃ The collected product is dried overnight at vacuum dryer at RT.

Example 46

Preparation of potassium molybdate

1 g of potassium formate is dissolved in 50 mL of 2-propanol and 100 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of potassium formate to molybdenum trioxide as 10: 1. Solution is stirred for several minutes at RT. The reaction is earned out at room temperature, up to the boiling point of the solvent. The yellowish solid K₂M0₃O₁₀ is obtained, which is dried overnight at RT in a vacuum dryer.

Example 47

The procedure is similar as in Example 46, with the exception that potassium formate to molybdenum trioxide ratio is 1 :1 (w/w).

Example 48

Preparation of potassium molybdate

To 20 mL of 3% mol. aqueous solution of potassium acetate 500 mg of commercially available molybdenum trioxide is added, keeping the weight ratio of potassium formate to molybdenum trioxide as 16: 1. The solution is stirred for several minutes at RT. The white solid K₂(Mq₃qio)·(H₂0)₃ is collected and dried overnight at RT in vacuum dryer.

Example 49

The procedure is similar as in Example 48, with the exception that potassium acetate to molybdenum trioxide ratio is 1 : 1 (w/w).

Example 50

Preparation of potassium molybdate

2 g of potassium acetate and 1 g of potassium formate is dissolved in 25 mL of water, then 200 mg of commercially available molybdenum trioxide is added, keeping the weight ratio of potassium acetate and potassium formate to molybdenum trioxide as 15: 1. The solution is stirred, and left overnight at 40-65°C to precipitate K₂(Mq₃qio)·(H₂0)₃. The collected solid is dried at RT.

Example 51

Preparation of ammonium molybdate

4 g of ammonium acetate is dissolved in 50 mL of water and 200 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of ammonium acetate to molybdenum trioxide as 20: 1. Solution is stirred for several minutes at RT. The reaction is earned out at room temperature, up to the boiling point of the solvent. The solid (NH₄)₆(Mq₇q₂₄)·(H₂0)₄ is obtained, which is dried overnight at 40°C in a vacuum dryer. Diffractogram presented in fig. 15 confirms the crystal structure of the material.

Example 52

The procedure is similar as in Example 51 , with the exception that ammonium acetate to molybdenum trioxide ratio is 1 :1 (w/w).

Example 53

Preparation of ammonium molybdate

To 500 mg of commercially available molybdenum trioxide 50 mL of supernatant obtained in the procedure descibed in Example 51 is added, keeping the weight ratio of ammonium formate to molybdenum trioxide at least 1 :1. The solution is left to precipitate solid (NH₄)₆(MO₇0₂₄)·(H20)₄. The collected product is dried overnight at vacuum dryer at RT.

Example 54

Preparation of ammonium molybdate

1 g of ammonium acetate is dissolved in 50 mL of 2-propanol and 100 mg of commercially available molybdenum trioxide (e.g. Alfa Aesar) is added, keeping the mass ratio of ammonium acetate to molybdenum trioxide as 10: 1 Solution is stirred for several minutes at RT. The reaction is carried out at room temperature, up to the boiling point of the solvent. The yellowish solid (NH₄)₆(Mo₇0₂₄) is obtained, which is dried overnight at RT in a vacuum dryer.

Example 55

The procedure is similar as in Example 54, with the exception that ammonium acetate to molybdenum trioxide ratio is 1 :1 (w/w).

Example 56

Preparation of ammonium molybdate

To 20 mL of 3% mol. aqueous solution of ammonium formate 500 mg of commercially available molybdenum trioxide is added, keeping the weight ratio of ammonium acetate to molybdenum trioxide as 4: 1. The solution is stirred for several minutes at RT. The white solid (NH4)6(MO₇0₂4)·(H₂0)4 is collected and dried overnight at 40°C in vacuum dryer.

Example 57

The procedure is similar as in Example 56, with the exception that ammonium fonnate to molybdenum trioxide ratio is 1:1 (w/w).

Example 58

Preparation of ammonium molybdate

1.8 g of ammonium acetate and 1.7 g of ammonium formate is dissolved in 25 mL of water, then 500 mg of commercially available molybdenum trioxide is added, keeping the weight ratio of ammonium acetate and ammonium formate to molybdenum trioxide as 7:1. The solution is stirred, and left overnight at 40-65°C to precipitate (NH₄)₆(Mo₇0₂₄) •(H₂0)₄. The collected solid is dried at RT.

In analogous way as described in the examples, mixture of organic salt of ammonium or potassium or cesium or rubidium can be used in a preparation method of other inorganic salts, disclosed in the invention. Example 59

Preparation of ammonium metavanadate

3.9 g of ammonium formate is dissolved in 50 mL of water and 50 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of ammonium formate to vanadium pentoxide as 78:1. The solution is mixed at room temperature for complete dissolution of vanadium pentoxide. The reaction is earned out at room temperature, up to the boiling point of the solvent. In the next step, the volume of the solution is reduced by evaporation of the solvent and the ammonium metavanadate crystals precipitates. Diffractogram presented in fig. 16 confirms the crystal structure of ammonium metavanadte. Fig. 17 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 59 NH₄VO₃ microcrystals not bigger than 50 pm can be prepared.

Example 60

The procedure is similar as in Example 59, with the exception that 50 mg of nanostructural vanadium pentoxide, obtained by known method is used. Nanostructural V₂O₅ is obtained in sol-gel method by mixing 1.5 mL of vanadium(V) oxytripropoxide and 10 mL of anhydrous ethanol and 0.5 pL of acetyl acetone. The obtained sol is dried at 50°C to obtain xerogel. The xerogel is calcined at 600-650°C in oxidizing atmosphere, giving 1 g of nanostructural V2O5.

Example 61

The procedure is similar as in Example 59, with the exception that ammonium formate to vanadium pentoxide ratio is 1: 1 (w/w).

Example 62

Preparation of ammonium metavanadate

4 g of ammonium formate is dissolved in 50 mL of formamide and 50 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of ammonium formate to vanadium pentoxide as 80: 1. The solution is stirred at room temperature for complete dissolution of vanadium pentoxide. The reaction is carried out at room temperature. The white solid is collected and dried overnight at RT in vacuum dryer. Fig. 18 presents FTIR spectrum of ammonium metavanadate obtained by procedure described in Example 62. The presented spectmm is identical with the reference spectrum in NIST database. Fig. 19 shows SEM image of obtained material. Presented image reveals, that by method disclosed in Example 62, urchin-like nanostructural NH₄VO₃ can be prepared.

Example 63

The procedure is similar as in Example 62, with the exception that ammonium formate to vanadium pentoxide ratio is 1: 1 (w/w).

Example 64

The procedure is similar as in Example 62, with the exception that nanostructural vanadium pentoxide is used. Fig. 20 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 64, NH₄VO₃ nanocrystals of average dimension 100-300 nm are obtained.

Example 65

Preparation of ammonium metavanadate

50 mg of ammonium formate is dissolved in 50 mL of N-methylpirrolidone and 50 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of ammonium formate to vanadium pentoxide as 1: 1. The solution is mixed at room temperature for complete dissolution of vanadium pentoxide. The reaction is carried out at room temperature. The white solid is collected and dried overnight at RT in vacuum dryer.

Example 66

The procedure is similar as in Example 65, with the exception that ammonium formate to vanadium pentoxide ratio is 2: 1 (w/w). Example 67

Preparation of ammonium metavanadate

10 g of ammonium acetate is dissolved in 50 mL of water and 50 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the actetate to vanadium pentoxide ratio as 200: 1. The solution is mixed at room temperature for complete dissolution of vanadium pentoxide. The precipitated solid is collected and dried overnight at RT. Fig. 21 presents confocal microscope image of obtained material. Presented image reveals, that by method disclosed in Example 67, the flower-like NH₄VO₃ microcrystals can be prepared.

Example 68

To 50 mg of commercially available vanadium pentoxide 50 mL of supernatant obtained in the procedure descibed in Example 67 is added, keeping the weight ratio of ammonium acetate to vanadium pentoxide at least 1 :1. The solution is left to precipitate solid ammonium metavanadte, which is dried in a vaccum dryer at RT.

Example 69

Preparation of ammonium metavanadate

2.5 g of ammonium acetate is dissolved in 50 mL of formamide and 50 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the ammonium acetate to vanadium pentoxide ratio as 50: 1. The solution is stirred at room temperature for several minutes and left to precipitate solid ammonium metavanadate. The precipitated solid is collected and dried overnight at RT.

Example 70

Preparation of ammonium metavanadate

To 50 mg of commercially available vanadium pentoxide 50 mL of supernatant obtained in the procedure descibed in Example 69 is added, keeping the weight ratio of ammonium acetate to vanadium pentoxide at least 1 : 1. The solution is left to precipitate solid ammonium metavanadte, which is dried in a vaccum dryer at RT. Example 71

The procedure is similar as in Example 69, with the exception that ammonium acetate to vanadium pentoxide ratio is 1 : 1 (w/w).

Example 72

Preparation of ammonium metavanadate

1.4 g of ammonium acetate and 1.6 g of ammonium formate is dissolved in 25 mL of formamide, then 300 mg of commercially available vanadium pentoxide is added, keeping the weight ratio of ammonium acetate and ammonium formate to vanadium pentoxide as 10: 1. The solution is stirred, and left overnight at 40-65°C to precipitate NFI4VO3. The collected solid is dried at RT. Fig. 22 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 72, elongated microcrystals of NH4VO3 can be prepared.

Example 73

Preparation of ammonium metavanadate

To 300 mg of nanostructural vanadium pentoxide 25 mL of supernatant obtained in the procedure described in Example 72 is added, keeping the weight ratio of ammonium acetate to vanadium pentoxide at least 1 : 1. The solution is left to precipitate solid ammonium metavanadte, which is dried in a vaccum dryer at RT. Fig. 23 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 73, urchin-like nanostructural NH4VO3 can be prepared.

Example 74

Preparation of ammonium metavanadate

1.6 g of ammonium acetate and 1.6 g of ammonium formate is dissolved in 25 mL of water, then 300 mg of commercially available vanadium pentoxide is added, keeping the weight ratio of ammonium acetate and ammonium formate to vanadium pentoxide as 10: 1. The solution is stirred, and left overnight to precipitate NH₄VO₃. The collected solid is dried at RT. Fig. 24 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 74, desert rose-like microcrystals of NH₄VO₃ can be prepared.

Example 75

Preparation of ammonium metavanadate

In 25 mL of formamide and deionized water in a volume ratio as 1 : 1, 3.2 g of ammonium formate is dissolved and 300 mg of commercially available vanadium pentoxide (e.g. Alfa Aesar) is added, keeping the weight ratio of ammonium formate to vanadium pentoxide as 10:1. The solution is stirred for several minutes at RT. The precipitated ammonium metavandate is dried in vacuum dryer overnight at rt. Fig. 25 presents SEM image of obtained material. Presented image reveals, that by method disclosed in Example 75, NH₄VO₃ microcrystals of polygon prism shape can be prepared.

Claims

1. Method for manufacturing of inorganic salt of general formula A_xM_yO_z, where A: .NH₄ ⁺ or K⁺ or Rb⁺ or Cs⁺; M: Mo or V, O: oxygen, comprising precipitation of solids from molybdenum trioxide or vanadium pentoxide solution by potassium or rubidium or cesium or ammonium salt, characterized in that, the salt is at least one organic salt of potassium or rubidium or cesium or ammonium, which is being dissolved in at least one solvent and the obtained solution is being mixed with molybdenum trioxide or vanadium pentoxide, keeping the weight ratio of potassium or rubidium or cesium or ammonium salt to molybdenum trioxide or vanadium pentoxide as at least 1 : 1, and then the obtained mixture is left until molybdates or vanadates is precipitated.

2. The method according to claim 1, wherein water and/or organic solvent is used.

3. The method according to claim 1, wherein weight ratio of organic salt of potassium or rubidium or cesium or ammonium to molybdenum trioxide or vanadium pentoxide is from 1 :1 to 200: 1.

4. The method according to claim 1, wherein molybdenum trioxide or vanadium pentoxide in nanocrystalline form is used.

5. The method according to claim 1 or 2 or 3 or 4, wherein potassium or rubidium or cesium or ammonium formate and/or acetate is used.

6. The method according to claim 1 or 2 or 3 or 4 or 5, wherein the precipitation is being earned out at room temperature up to the boiling point of the solvent or the mixture of thereof.

7. The according to claim 1 or 2 or 3 or 4 or 5 or 6, wherein an excess of organic salt to molybdenum trioxide or vanadium pentoxide is used, and the supernatant obtained after first precipitation of molybdates or vanadates, containing potassium or rubidium or cesium or ammonium salt is further used in the second precipitation of molybdates or vanadates by adding to the supernatant molybdenum trioxide or vanadium pentoxide, keeping the weight ratio of organic salt to molybdenum oxide or vanadium pentoxide at least 1 :1.