METHOD FOR THE MANUFACTURE OF Fe(II)P/Fe(II)MetP COMPOUNDS

Abstract

A method for the manufacture of crystal water-free iron(II) orthophosphate of the general formula Fe.sub.3(PO.sub.4).sub.2 or crystal water-free iron(II) metal orthophosphate, iron(II) metal pyrophosphate or iron(II) metal metaphosphate of the general formula Fe.sub.aMet.sub.b(PO.sub.c).sub.d, where a is a number from 1 to 5, b is a number from >0 to 5, c is a number from 2.5 to 5, d is a number from 0.5 to 3 and Met represents one or more metals selected from the group consisting of K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d block), in particular Sc, Y, La, Ti, Zr, Hf, Nb, Ta, Cr, Mo, W, Mn, Cu, Zn and the metals and semimetals of the third, fourth and fifth main groups, in particular B, Al, Ga, In, Si, Sn, Sb, Bi and the lanthanoids.

Claims

1. A method for the manufacture of crystal water-free iron(II) orthophosphate of the general formula Fe.sub.3(PO.sub.4).sub.2 or crystal water-free iron(II) metal orthophosphate, iron(II) metal pyrophosphate or iron(II) metal metaphosphate of the general formula Fe.sub.aMet.sub.b(PO.sub.c).sub.d, where a is a number from 1 to 5, b is a number from >0 to 5, c is a number from 2.5 to 5, d is a number from 0.5 to 3 and Met represents one or more metals selected from the group consisting of K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d block), the metals and semimetals of the third, fourth and fifth main groups, and the lanthanoids or combinations of the above mentioned phosphates with the stages: a) manufacture of a mixture containing: i) iron compounds (A) selected from Fe(III) compounds, Fe(III)/Fe(II) compounds and mixtures of these in a percentage of 20% to 90% by weight of the mixture selected from the group consisting of oxides, hydroxides, oxide hydroxides, carbonates, carboxylates such as oxalates, formates, acetates, citrates, lactates, orthophosphates, phosphonates, metaphosphates, pyrophosphates, sulphates and mixtures of those mentioned above, ii) reduction agent (B) in a percentage of 5% to 50% by weight of the mixture selected from the group consisting of phosphonic acid [H.sub.3PO.sub.3], phosphorus trioxide [P.sub.2O.sub.3], phosphinic acid [H.sub.3PO.sub.2], phosphorus tetroxide [P.sub.2O.sub.4], hypodiphosphoric acid [H.sub.4P.sub.2O.sub.6], diphosphoric acid [H.sub.4P.sub.2O.sub.5], hypodiphosphonic acid [H.sub.4P.sub.2O.sub.4], Fe salts and Met salts of the above mentioned acids and mixtures of the above as solids, aqueous solutions or suspensions, iii) optional phosphate donor (C) in a percentage of 0% to 50% by weight of the mixture selected from phosphoric acid [H.sub.3PO.sub.4] as an aqueous solution, metal phosphate [Met.sub.x(PO.sub.4).sub.z] or acid metal phosphate [Met.sub.xH.sub.y(PO.sub.4).sub.z] with 1x4, 1y5 and 1z4 as a solid or aqueous solution or suspension, diphosphoric acid [H.sub.4P.sub.2O.sub.7], metaphosphoric acid [(HPO.sub.3).sub.n] with n3 or their salts, phosphorus pentoxide [P.sub.2O.sub.5] or mixtures of the above, where Met is defined as above, iv) optional metal (Met) donor (D) in a percentage of 0% to 50% by weight of the mixture selected from metal compounds of one or more metals from the group consisting of K, Rb, Cs, Mg, Ca, Sr, Ba, the transition metals (d block), and the metals and semimetals of the third, fourth and fifth main group, and the lanthanoids, and selected from the oxides, hydroxides, oxide hydroxides, carbonates, oxalates, formates, acetates, citrates, lactates, orthophosphates, pyrophosphates and sulphates of the above mentioned metals and mixtures of these, whereby the share of the weight of components (A) to (D) of the mixture is based on the percentage of the substances not including any solvent and/or suspension agent. b) the mixture obtained, where it contains aqueous and/or organic solvents, is dried at a temperature of less than 400 C., c) the dry or dried mixture is treated at a temperature in the range from 400 to 1200 C.

2. The method according to claim 1, wherein the drying in stage b) is carried out by convective drying at a temperature in the range from 100 to 400 C.

3. The method according to claim 1, wherein the temperature treatment in stage c) is carried out in an inert gas atmosphere or reducing gas atmosphere.

4. The method according to claim 1, wherein the temperature treatment in stage c) is carried out in a rotary kiln.

5. The method according to claim 1, wherein the temperature treatment in stage c) is carried out at a temperature in the range from 500 to 1100 C.

6. The method according to claim 1, wherein the iron(II) phosphate is crystal water-free iron(II) orthophosphate of the general formula Fe.sub.3(PO.sub.4).sub.2 and has the graftonite crystal structure.

7. The method according to claim 1, wherein the iron(II) phosphate is a mixed metal crystal water-free iron(II) metal orthophosphate of the general formula Fe.sub.aMet.sub.b(PO.sub.c).sub.d, where Met represents one or a combination of the metals potassium (K), magnesium (Mg) and zinc (Zn).

8. The method according to claim 1, wherein the iron(II) phosphate is a mixed metal crystal water-free iron(II) metal pyrophosphate of the general formula Fe.sub.aMet.sub.b(P.sub.2O.sub.7).sub.d, where Met represents one or a combination of the metals calcium (Ca), strontium (Sr) and barium (Ba).

9. The method according to claim 1, wherein the Fe(II) and/or Fe(III)/Fe(II) compounds used as iron compound (A) are selected from oxides, oxide hydroxides, hydroxides, orthophosphates, pyrophosphates, metaphosphates and sulphates.

10. The method according to claim 1, wherein the product obtained in stage c) after temperature treatment is adjusted in terms of particle size.

11. The method according to claim 7, wherein the iron(II) metal orthophosphate is KFePO.sub.4, K(Fe.sub.0.90Zn.sub.0.10)PO.sub.4, K(Fe.sub.0.75Mn.sub.0.25)PO.sub.4, K(Fe.sub.0.75Zn.sub.0.25)PO.sub.4 or K(Fe.sub.0.75Mg.sub.0.25)PO.sub.4.

12. The method according to claim 8, wherein the iron(II) metal pyrophosphate is CaFeP.sub.2O.sub.7, SrFeP.sub.2O.sub.7 or BaFeP.sub.2O.sub.7.

Description

[0076] The invention will now be described in greater detail through embodiments and the attached figures.

[0077] FIG. 1 shows the x-ray diffractogram of crystal water-free Fe.sub.2P.sub.2O.sub.7 manufactured according to the invention in line with manufacturing example 1.

[0078] FIG. 2 shows the x-ray diffractogram of crystal water-free Mg.sub.1.5Fe.sub.1.5(PO.sub.4).sub.2 and Fe.sub.3(PO.sub.4).sub.2 manufactured according to the invention in line with manufacturing example 2.

[0079] FIG. 3 shows the x-ray diffractogram of crystal water-free Fe.sub.3(PO.sub.4).sub.2 manufactured according to the invention in line with manufacturing example 3.

[0080] FIG. 4 shows the x-ray diffractogram of crystal water-free KFe(PO.sub.4) manufactured according to the invention in line with manufacturing example 4.

[0081] FIG. 5 shows the x-ray diffractogram of crystal water-free KFe.sub.0.90Zn.sub.0.10(PO.sub.4) manufactured according to the invention in line with manufacturing example 5.

[0082] FIG. 6 shows the x-ray diffractogram of crystal water-free KFe.sub.0.75Zn.sub.0.25(PO.sub.4) manufactured according to the invention in line with manufacturing example 6.

[0083] FIG. 7 shows the x-ray diffractogram of crystal water-free KFe.sub.0.75Mn.sub.0.25(PO.sub.4) manufactured according to the invention in line with manufacturing example 7.

[0084] FIG. 8 shows the x-ray diffractogram of crystal water-free BaFeP2O7 manufactured according to the invention in line with manufacturing example 8.

[0085] FIG. 9 shows the particle size distribution of crystal water-free Fe.sub.3(PO.sub.4).sub.2 manufactured according to the invention in line with manufacturing example 3.

EXAMPLES

X-Ray Diffractometry (XRD)

[0086] Of the products manufactured according to the examples below, x-ray diffraction measurements (XRD) are taken using a D8 Advance A25-type diffractometer (Bruker) and CuK radiation.

[0087] The products and their crystal structures were identified on the basis of corresponding reference diffractograms (Powder Diffraction Files; PDF) from the ICDD (International Centre for Diffraction Data), previously JCPDS (Joint Committee on Powder Diffraction Standards) database. If no PDF cards were available for the products manufactured, PDF cards for isotype compounds were used (=compounds of the same structural type).

Elementary Analysis

[0088] Elementary analyses were carried out by means of x-ray fluorescence analysis (XRF) using an Axios FAST spectrometer (PANalytical) in order to determine and confirm the stoichiometries of the products manufactured.

Particle Size Determination

[0089] The person skilled in the art can use common methods such as light scattering and microscopic methods to determine the average particle size. The average particle sizes indicated here were determined used a laser particle size measuring device (model LA-950V2 by Horiba; software version 7.2).

Manufacturing Example 1Crystal Water-Free Fe.SUB.2.P.SUB.2.O.SUB.7

[0090] A suspension of

[0091] i) 35.5 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0092] ii) 16.5 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0093] iii) 26.5 kg 75% phosphoric acid [H.sub.3PO.sub.4] and

[0094] LA: 220 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 4 h in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 700 C. An almost colourless to slightly pink product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 1. The product was identified using PDF card 01-072-1516.

Manufacturing Example 2Phase Mixture of Crystal Water-Free Mg.SUB.1.5.Fe.SUB.1.5.(PO.SUB.4.).SUB.2 .and Fe.SUB.3.(PO.SUB.4.).SUB.2

[0095] A suspension of

[0096] i) 8.45 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0097] ii) 7.95 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0098] iii) 19.6 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O],

[0099] iv) 8.43 kg magnesium carbonate [MgCO.sub.3] and

[0100] LA: 160 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 3 h in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 750 C. An almost colourless product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 2. The product was identified using the PDF cards as a phase mixture of a main phase Mg.sub.1.5Fe.sub.1.5(PO.sub.4).sub.2 (PDF card 01-071-6793) and a subsidiary phase Fe3(PO4)2 (PDF card 00-49-1087).

Manufacturing Example 3Crystal Water-Free Fe.SUB.3.(PO.SUB.4.).SUB.2

[0101] A suspension of

[0102] i) 21.75 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.31H.sub.2O],

[0103] ii) 12.15 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0104] iii) 10.3 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O] and

[0105] LA: 140 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 90 minutes in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 750 C. An almost colourless product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 3. The product crystallises in the graftonite structure and was identified using PDF card 00-49-1087. The product was ground such that 50% by weight of the product had a particle size of less than 3 m. The particle size distribution of the ground product is shown in FIG. 9.

Manufacturing Example 4Manufacture of Crystal Water-Free KFe(PO.SUB.4.)

[0106] A suspension of

[0107] i) 11.80 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0108] ii) 10.70 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0109] iii) 24.8 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O]

[0110] IV) 29.8 kg 50% lye [KOH]

[0111] V) 1.0 kg 75% phosphoric acid [H.sub.3PO.sub.4] and

[0112] LA: 110 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 3 h in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 650 C. A pale light green product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 4. The product was identified using PDF card 01-076-4615.

Manufacturing Example 5Crystal Water-Free KFe.SUB.0.90.Zn.SUB.0.10.(PO.SUB.4.)

[0113] A suspension of

[0114] i) 10.60 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0115] ii) 9.65 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0116] iii) 22.30 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O]

[0117] IV) 2.15 kg zinc oxide [ZnO]

[0118] IV) 29.8 kg 50% lye [KOH]

[0119] V) 4.15 kg 75% phosphoric acid [H.sub.3PO.sub.4] and

[0120] LA: 120 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 2 h in a form gas atmosphere (5% by volume H2 in N2) at 600 C. An light grey product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 5. The product is a new structure type which appears to be closely linked to the KFe(PO.sub.4) structure according to PDF card 01-076-4615.

Manufacturing Example 6Crystal Water-Free KFe.SUB.0.75.Zn.SUB.0.25.(PO.SUB.4.)

[0121] A suspension of

[0122] i) 8.85 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0123] ii) 8.05 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0124] iii) 18.60 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O]

[0125] IV) 5.40 kg zinc oxide [ZnO]

[0126] IV) 29.8 kg 50% lye [KOH]

[0127] V) 9.30 kg 75% phosphoric acid [H.sub.3PO.sub.4] and

[0128] LA: 120 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 2 h in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 600 C. A light grey product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 6. The product is not known from the literature. It crystallises in an isotype manner to form KZn(PO.sub.4) according to PDF card 01-081-1034.

Manufacturing Example 7Crystal Water-Free KFe.SUB.0.75.Mn.SUB.0.25.(PO.SUB.4.)

[0129] A suspension of

[0130] i) 8.85 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0131] ii) 8.05 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0132] iii) 18.60 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O]

[0133] IV) 8.85 kg manganese carbonate hydrate [MnCO.sub.3 H.sub.2O]

[0134] IV) 29.8 kg 50% lye [KOH]

[0135] V) 9.30 kg 75% phosphoric acid [H.sub.3PO.sub.4] and

[0136] LA: 140 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 2 h in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 600 C. An light grey product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 7. The product is not known from the literature. It crystallises in an isotype manner to form KFe(PO.sub.4) according to PDF card 01-076-4615.

Manufacturing Example 8Crystal Water-Free BaFeP.SUB.2.O.SUB.7

[0137] A suspension of

[0138] i) 8.70 kg iron(III) oxide-hydroxide [FeO(OH) or Fe.sub.2O.sub.3 1H.sub.2O],

[0139] ii) 8.20 kg 98% phosphonic acid [H.sub.3PO.sub.3],

[0140] iii) 19.05 kg iron(III) phosphate dihydrate [FePO.sub.4 2H.sub.2O]

[0141] IV) 63.09 kg barium hydroxide octahydrate [Ba(OH).sub.2 8H.sub.2O]

[0142] V) 26.15 kg 75% phosphoric acid [H.sub.3PO.sub.4] and

[0143] LA: 250 kg water

was spray granulated. The granulate obtained in this way was temperature treated in a rotary kiln for an average residence time of 4 h in a form gas atmosphere (5% by volume H.sub.2 in N.sub.2) at 800 C. A light grey product is obtained. The x-ray diffractogram (XRD) of the product is shown in FIG. 8. The product crystallises in an isotype manner to form BaCoP.sub.2O.sub.7 according to PDF card 01-084-1833.