US2920939A - Method of producing phosphates - Google Patents
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- US2920939A US2920939A US640256A US64025657A US2920939A US 2920939 A US2920939 A US 2920939A US 640256 A US640256 A US 640256A US 64025657 A US64025657 A US 64025657A US 2920939 A US2920939 A US 2920939A
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- tripolyphosphate
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- orthophosphate
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- alkali metal
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- 229910019142 PO4 Inorganic materials 0.000 title claims description 29
- 238000000034 method Methods 0.000 title claims description 20
- 235000021317 phosphate Nutrition 0.000 title description 23
- 150000003013 phosphoric acid derivatives Chemical class 0.000 title description 7
- 235000019832 sodium triphosphate Nutrition 0.000 claims description 47
- 239000000203 mixture Substances 0.000 claims description 39
- NBIIXXVUZAFLBC-UHFFFAOYSA-K phosphate Chemical compound [O-]P([O-])([O-])=O NBIIXXVUZAFLBC-UHFFFAOYSA-K 0.000 claims description 29
- UNXRWKVEANCORM-UHFFFAOYSA-I triphosphate(5-) Chemical compound [O-]P([O-])(=O)OP([O-])(=O)OP([O-])([O-])=O UNXRWKVEANCORM-UHFFFAOYSA-I 0.000 claims description 21
- 239000010452 phosphate Substances 0.000 claims description 19
- 238000006243 chemical reaction Methods 0.000 claims description 17
- 229910052783 alkali metal Inorganic materials 0.000 claims description 10
- 229910000272 alkali metal oxide Inorganic materials 0.000 claims description 7
- 150000001340 alkali metals Chemical class 0.000 claims description 6
- DLYUQMMRRRQYAE-UHFFFAOYSA-N tetraphosphorus decaoxide Chemical compound O1P(O2)(=O)OP3(=O)OP1(=O)OP2(=O)O3 DLYUQMMRRRQYAE-UHFFFAOYSA-N 0.000 claims description 6
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 5
- 230000005494 condensation Effects 0.000 claims description 4
- 238000009833 condensation Methods 0.000 claims description 4
- 230000008018 melting Effects 0.000 claims description 4
- 238000002844 melting Methods 0.000 claims description 4
- 239000011734 sodium Substances 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- 239000000376 reactant Substances 0.000 description 6
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 5
- BNIILDVGGAEEIG-UHFFFAOYSA-L disodium hydrogen phosphate Chemical compound [Na+].[Na+].OP([O-])([O-])=O BNIILDVGGAEEIG-UHFFFAOYSA-L 0.000 description 5
- 238000004519 manufacturing process Methods 0.000 description 5
- -1 orthophosphate dihydrate Chemical class 0.000 description 5
- 239000011541 reaction mixture Substances 0.000 description 5
- 150000003839 salts Chemical class 0.000 description 5
- 229910052708 sodium Inorganic materials 0.000 description 5
- AJPJDKMHJJGVTQ-UHFFFAOYSA-M sodium dihydrogen phosphate Chemical compound [Na+].OP(O)([O-])=O AJPJDKMHJJGVTQ-UHFFFAOYSA-M 0.000 description 5
- 239000007787 solid Substances 0.000 description 4
- 239000000654 additive Substances 0.000 description 3
- 230000000996 additive effect Effects 0.000 description 3
- KDQPSPMLNJTZAL-UHFFFAOYSA-L disodium hydrogenphosphate dihydrate Chemical compound O.O.[Na+].[Na+].OP([O-])([O-])=O KDQPSPMLNJTZAL-UHFFFAOYSA-L 0.000 description 3
- 238000001704 evaporation Methods 0.000 description 3
- 239000012535 impurity Substances 0.000 description 3
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 2
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 2
- ZLMJMSJWJFRBEC-UHFFFAOYSA-N Potassium Chemical compound [K] ZLMJMSJWJFRBEC-UHFFFAOYSA-N 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 239000007795 chemical reaction product Substances 0.000 description 2
- 239000013068 control sample Substances 0.000 description 2
- 230000008020 evaporation Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 125000005341 metaphosphate group Chemical group 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 229910052698 phosphorus Inorganic materials 0.000 description 2
- 239000011574 phosphorus Substances 0.000 description 2
- 229910052700 potassium Inorganic materials 0.000 description 2
- 239000011591 potassium Substances 0.000 description 2
- GNSKLFRGEWLPPA-UHFFFAOYSA-M potassium dihydrogen phosphate Chemical compound [K+].OP(O)([O-])=O GNSKLFRGEWLPPA-UHFFFAOYSA-M 0.000 description 2
- KKCBUQHMOMHUOY-UHFFFAOYSA-N sodium oxide Chemical compound [O-2].[Na+].[Na+] KKCBUQHMOMHUOY-UHFFFAOYSA-N 0.000 description 2
- 229910001948 sodium oxide Inorganic materials 0.000 description 2
- VZWGHDYJGOMEKT-UHFFFAOYSA-J sodium pyrophosphate decahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.[Na+].[Na+].[Na+].[Na+].[O-]P([O-])(=O)OP([O-])([O-])=O VZWGHDYJGOMEKT-UHFFFAOYSA-J 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- XOFFIPPBMPVZBY-UHFFFAOYSA-K trisodium;[hydroxy(oxido)phosphoryl] phosphate;hydrate Chemical compound O.[Na+].[Na+].[Na+].OP([O-])(=O)OP([O-])([O-])=O XOFFIPPBMPVZBY-UHFFFAOYSA-K 0.000 description 2
- LEAHFJQFYSDGGP-UHFFFAOYSA-K trisodium;dihydrogen phosphate;hydrogen phosphate Chemical compound [Na+].[Na+].[Na+].OP(O)([O-])=O.OP([O-])([O-])=O LEAHFJQFYSDGGP-UHFFFAOYSA-K 0.000 description 2
- MOMKYJPSVWEWPM-UHFFFAOYSA-N 4-(chloromethyl)-2-(4-methylphenyl)-1,3-thiazole Chemical compound C1=CC(C)=CC=C1C1=NC(CCl)=CS1 MOMKYJPSVWEWPM-UHFFFAOYSA-N 0.000 description 1
- 241000331231 Amorphocerini gen. n. 1 DAD-2008 Species 0.000 description 1
- QXNVGIXVLWOKEQ-UHFFFAOYSA-N Disodium Chemical compound [Na][Na] QXNVGIXVLWOKEQ-UHFFFAOYSA-N 0.000 description 1
- KEAYESYHFKHZAL-UHFFFAOYSA-N Sodium Chemical compound [Na] KEAYESYHFKHZAL-UHFFFAOYSA-N 0.000 description 1
- 239000002253 acid Substances 0.000 description 1
- 239000003513 alkali Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 238000011109 contamination Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- ZPWVASYFFYYZEW-UHFFFAOYSA-L dipotassium hydrogen phosphate Chemical compound [K+].[K+].OP([O-])([O-])=O ZPWVASYFFYYZEW-UHFFFAOYSA-L 0.000 description 1
- XQGPKZUNMMFTAL-UHFFFAOYSA-L dipotassium;hydrogen phosphate;trihydrate Chemical compound O.O.O.[K+].[K+].OP([O-])([O-])=O XQGPKZUNMMFTAL-UHFFFAOYSA-L 0.000 description 1
- 235000019820 disodium diphosphate Nutrition 0.000 description 1
- GYQBBRRVRKFJRG-UHFFFAOYSA-L disodium pyrophosphate Chemical compound [Na+].[Na+].OP([O-])(=O)OP(O)([O-])=O GYQBBRRVRKFJRG-UHFFFAOYSA-L 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 150000004687 hexahydrates Chemical class 0.000 description 1
- 230000036571 hydration Effects 0.000 description 1
- 238000006703 hydration reaction Methods 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- BTRXYXNWHKNMAB-UHFFFAOYSA-N phosphoric acid;dodecahydrate Chemical compound O.O.O.O.O.O.O.O.O.O.O.O.OP(O)(O)=O BTRXYXNWHKNMAB-UHFFFAOYSA-N 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 235000019983 sodium metaphosphate Nutrition 0.000 description 1
- 239000001488 sodium phosphate Substances 0.000 description 1
- 235000011008 sodium phosphates Nutrition 0.000 description 1
- 239000007790 solid phase Substances 0.000 description 1
- TWQULNDIKKJZPH-UHFFFAOYSA-K trilithium;phosphate Chemical compound [Li+].[Li+].[Li+].[O-]P([O-])([O-])=O TWQULNDIKKJZPH-UHFFFAOYSA-K 0.000 description 1
- LSKHZZSZLMMIMU-UHFFFAOYSA-K tripotassium;hydron;phosphonato phosphate Chemical compound [K+].[K+].[K+].OP([O-])(=O)OP([O-])([O-])=O LSKHZZSZLMMIMU-UHFFFAOYSA-K 0.000 description 1
- RYFMWSXOAZQYPI-UHFFFAOYSA-K trisodium phosphate Chemical class [Na+].[Na+].[Na+].[O-]P([O-])([O-])=O RYFMWSXOAZQYPI-UHFFFAOYSA-K 0.000 description 1
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Classifications
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
- C01B25/00—Phosphorus; Compounds thereof
- C01B25/16—Oxyacids of phosphorus; Salts thereof
- C01B25/26—Phosphates
- C01B25/38—Condensed phosphates
- C01B25/40—Polyphosphates
- C01B25/41—Polyphosphates of alkali metals
- C01B25/412—Preparation from alkali metal orthophosphates
Definitions
- This invention relates to novel improvements in methods for producing alkali metal tripolyphosphates, such as the sodium, potassium, lithium, etc., tripolyphosphates.
- tripolyphosphates now produced commercially are manufactured by a so-called solid phase process which involves heating a mixture of phosphates other than tripolyphosphates (e.g., a mixture of rnonosodium orthophosphate and disodium orthophosphate) at a temperature below the melting point of the tripolyphosphate until the mixture has been converted to the desired tripolyphosphate.
- a mixture of phosphates other than tripolyphosphates e.g., a mixture of rnonosodium orthophosphate and disodium orthophosphate
- the time required for conversion to tripolyphosphate in such a process will vary somewhat depending upon such factors as temperature, particular phosphate reactants selected, etc. It has now been found that these processes can be carried out much more effectively if an appreciable amount of crystalline tripolyphosphate is initially introduced into the reaction mixture.
- the phosphate mixtures which are useful for conversion according to the present process are those in which the overall molecular ratio of alkali metal oxide to phosphorus pentoxide is between about/1.5 and about "1.8, and preferably between about 1.6 and about 1.7, and in which the overall molecular proportion of alkali rnetal oxide to water of constitution (as distinguished from Waterof hydration) is less than about IQ, and preferably less than about 5.
- the phosphate mixtures can be made up of ortho., pyro-,, meta-, or intermediate glassy phosphates, or combinations thereof, can beeit'her hydrated or anhydrous, and may include .normal'salts as Well acid salts. While it' is generally more convenient to use a mixture of only two different phosphate salts, mixtures of more thantwo can 'belutilized equally well. 1
- Suitable phosphate mixtures for conversion to tripolyphosphates according to the present invention are as follows:
- the propor tion of the particular phosphate reactants chosen should be adjusted so that the alkali metal oxides and-phosphorus ,pentoxide present in the mixture have a mole ratio of 5 :3 (the ratio of oxides in pure tripolyphosphate).
- the use of mixtures havinga mole ratio of alkali metal oxides to phosphor-us pentoxide other than 5: 3 will result in products containing non-tripolyphospha'teimpurities, the proportion of impurities increasing as the oxide'ratio of the reaction mixture departs ffarther from 5:3.
- the pres ent invention is applicable not only to phosphate mixtures containing a mole ratio of oxides of 5:3, but also to phosphate mixtures in which the ratio varies somearr m.
- Na P O --II sodium tripolyphosphate
- rea detai h r ina n e produced pr ctica ly completely free from impurities (such as insoluble metaphosphates) by making up reaction mixtures containing several times (e.g.', as much as -8 or 10 times). as much crystalline Na P O II as non-tripolyphosphate reactants.
- the temperatures utilized will be somewhat above 175 C., and preferably above about 200 C.
- the advantages of the present invention may be manifested in one or more of several ways, such as by greater yields of desired product, accelerated rates of reaction, greater degrees of freedom in selection of reaction conditions, etc.
- While the present invention is generally applicable to any of the alkali metal tripolyphosphates, it is particularly advantageously utilized in the production of sodium tripolyphosphatesand especially in the production of the so-called low-temperature sodium tripolyphosphate, Na P O -II.
- sodium tripolyphosphate, Na P O is known to be a polymorphic material, of which at least two separate and distinct solid crystalline modifications have been identified. These modifications are commonly referred to as Form I and Form II, and are designated by the formulae, Na P O -I and Na P O II, respectively. See Partridge et al., Journal of the American Chemical Society, vol. 63, page 454 et seq.).
- Na P O II is generally formed at temperatures below about 470 C., and preferably below about 400 C., whereas Na P O -I is generally formed at temperatures inexcess of about 500? C. Probably because of the lower conversion temperatures utilized, the conversion to Na P O II is somewhat slower than the conversion to Na P O -I, and is also more prone to production of a product having noticeably higher contamination with insoluble impuritiessuch as insoluble metaphosphates. By using the improved process of the present invention, it is possible to effectmarked improvements in both the conversion rate and product purity of Na P O II.
- any of the crystalline forms of sodium tripolyphosphate (for example, Na P O I, Na P O -lLor Na P O -6H O) can be used to improve the production Df N35P3010II, the Na P O 6-I and N35P3010'6H20 are found to be somewhat more effective than N215P3O10II.
- Na P O I, Na P O -lLor Na P O -6H O can be used to improve the production Df N35P3010II
- the Na P O 6-I and N35P3010'6H20 are found to be somewhat more effective than N215P3O10II.
- Example I One-tenth gram of powdered Na P O II and 1.9 grams of an equimolar mixture of Na HP,O and NaH P -Na HPO were thoroughly mixed together and heated in an open c'rucible for two hours in a muflle furnace at 200 C. At the same time, 2.0 grams of the equimolar mixture of Na HPOpwith NaI-I PO -Na HPO (but with no-Na P O added) was heated in the same furnace under the same conditions.
- the crystalline tripolyphosphate additive was introduced as a solid directly into the solid phosphate mixture which was to be converted to tripolyphosphate product.
- the tripolyphosphate additive can be introduced at earlier stages of the processsuch as during the prepartion of the phosphate mixture which is to be converted.
- the phosphate mixture utilized in Example 1 can be prepared by evaporating the water from a solution of two mole proportions of disodium orthophosphate and one mole proportion of monosodium'orthophosphate. If the desired amount of crystalline sodium tripolyphosphate additive is dissolved inthis solution prior to evaporation, the solids resulting from the evaporation will contain the necessary crystalline tripolyphosphate for carrying out the process of the present invention.
- alkali metal tripolyphosphates by condensation of a mixture of phosphates other than tripolyphosphates at a temperature below the melting point of said tripolyphosphate, said phosphate mixture having an overall molecular ratio of alkali metal oxide to phosphorus pentoxidebetween about 1.5 and about 1.8 and an overall molecular ratio of alkali metal oxide to water of constitution less than about 10, the improvement which comprises adding at least 1 percent by weight of crystalline alkali metal tripolyphosphate to said mixture of phosphates, thereby accelerating the rate of conversion of said mixture of phosphates to said alkali metal tripolyphosphate.
- alkali metal tripolyphosphate is sodium tripolyphosphate
- V 3 The method of claim 1, wherein the alkali metal tripolyphosphate is potassium tripolyphosphate.
- the method of producing sodium tripolyphosphate- II which comprises adding at least 1 percent by weight of a compound selected from the group consisting of sodium tripolyphosphate hexahydrate and sodium tripolyphosphate-I to a mixture of sodium phosphates other than sodium tripolyphosphate containing at least 10 percent by weight of orthophosphate and having an overall molecular ratio of Na O:P O between about 1.5 and about 1.8 and an overall molecular ratio of Na Ozwater of consti- References Cited in the file of this patent UNITED STATES PATENTS 2,419,148 King Apr. 15, 1947 2,493,809 Garrison Jan. 10, 1950 2,737,443 Wright Mar. 6, 1956 2,776,187 Pfengle Jan. 1, 1957
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Description
J. W. EDWARDS METHOD OF PRODUCING PHOSPHATES Filed Feb. 14, 1957 Jan. 12, 1960 0 O O 8 w 4 #55:: z h o l z kzwo Em 5 INVENTOR.
JAMES W. EDWARDS Bid/ f HIS AGENT TIME, IN MINUTES United States Patent 2,920,939 METHOD OF PRODUCING PHOSPHATES James W. Edwards, Dayton, Ohio, assignor to'Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware Application February 14, 1957, Serial No. 640,256
6 Claims. (Cl. 23-106) This invention relates to novel improvements in methods for producing alkali metal tripolyphosphates, such as the sodium, potassium, lithium, etc., tripolyphosphates.
Most of the tripolyphosphates now produced commercially are manufactured by a so-called solid phase process which involves heating a mixture of phosphates other than tripolyphosphates (e.g., a mixture of rnonosodium orthophosphate and disodium orthophosphate) at a temperature below the melting point of the tripolyphosphate until the mixture has been converted to the desired tripolyphosphate. The time required for conversion to tripolyphosphate in such a process will vary somewhat depending upon such factors as temperature, particular phosphate reactants selected, etc. It has now been found that these processes can be carried out much more effectively if an appreciable amount of crystalline tripolyphosphate is initially introduced into the reaction mixture.
The phosphate mixtures which are useful for conversion according to the present process are those in which the overall molecular ratio of alkali metal oxide to phosphorus pentoxide is between about/1.5 and about "1.8, and preferably between about 1.6 and about 1.7, and in which the overall molecular proportion of alkali rnetal oxide to water of constitution (as distinguished from Waterof hydration) is less than about IQ, and preferably less than about 5. .The phosphate mixtures can be made up of ortho., pyro-,, meta-, or intermediate glassy phosphates, or combinations thereof, can beeit'her hydrated or anhydrous, and may include .normal'salts as Well acid salts. While it' is generally more convenient to use a mixture of only two different phosphate salts, mixtures of more thantwo can 'belutilized equally well. 1
Examples of suitable phosphate mixtures for conversion to tripolyphosphates according to the present invention are as follows:
(l) 65 weight percent trisodium hydrogen pyrophosphate monohydrate and 35 weight percent disodium orthophosphate.
(2) 65 weight percent monosodium orthophosphate-disodium orthophosphate double salt and 35 weightpercent disodium orthophosphate. V r
(3) 60 weight percent monosodium orthophosphate-disodium orthophosphate double salt and 40 weight -percent disodium orthophosphate dihydrate. 1
(4) 60 Weight percent trisodium hydrogen pyrophosphate monohydrate and 40, Weight percent gdisodium orthophosphate dihydrate. I
('5) 22 weight percent monosodium orthophosphate and .78 weight percent disodium'orthophosphate.,
(6) 25 weight percent monosodium orthophosphate and "75 weight percent disodium orthophosphate dihydrate.
(7) 20 weight percent monosodiurn orthoph'osphate and 1 80 weight percent tetrasodium pyrophosphate decahydrate. H
. 2,920,939 ,Fatentecl Jan. 12, 196.0
(8) 39 percent .rnonosodium orthophosphate and 61 weight percent trisodium orthophosphate dodecahydrate.
(9) '9 weight percent sodium acid pyrophosphate, 85
weight percent tetrasodium pyrophosphate decahydrate and 6 weight percent monosodium orthophosphate.
(1Q) 15 weight percent sodium metaphosphate, 18 Weight percent .monosodium orthophosphate and 6'] weight percent disodium orthophosphate dihydrate.
( 11) 28 weight percent monopotassium orthophosphate and 72 Weight percent dipotassium orthophosphate.
(12) 5'6 weightpercent monopotassium orthophosphate and 44 weight percent tr-ipotassium orthophosphate.
(13) The double salt hydrate, KH PO .2K HPO .H O.
(14) 44 weight percent dipotassium orthophosphate trihydrate and 56 weight percent tripotassium monohydrogen pyrophosphate.
(l5) 64 weight percent monolithium orthophosphate-and 36 weight percent trilithium orthophosphate.
In order to produce t-ripolyphosphates having a mini? mum of other phosphate impurities therein, the propor tion of the particular phosphate reactants chosen should be adjusted so that the alkali metal oxides and-phosphorus ,pentoxide present in the mixture have a mole ratio of 5 :3 (the ratio of oxides in pure tripolyphosphate). The use of mixtures havinga mole ratio of alkali metal oxides to phosphor-us pentoxide other than 5: 3 will result in products containing non-tripolyphospha'teimpurities, the proportion of impurities increasing as the oxide'ratio of the reaction mixture departs ffarther from 5:3. As indicated before, "however, the pres ent invention is applicable not only to phosphate mixtures containing a mole ratio of oxides of 5:3, but also to phosphate mixtures in which the ratio varies somearr m.
The discovery upon which the present invention is predicated is that the conversion of the above-described phosphate mixtures to tripolyphosphategor to mixtures containing predominantly tripolyphosphates, can be carried out much more eiiectively and economically if some crystalline tripolyphosphate is initially present in the reaction mixture. .The exact amount of crystalline tripolyphosphate to be used will ;be largely dependentupon the economics. applicable to the particular process; but in general greater than 1 weightpercent, and preferably greater than about 2 weight percent will be most feasible. There is no upper limit to the amounts that can be used, but theeifectiveness per unit weight of added tripolyphosphate decreases somewhat with increasing amounts added, so that it will often be uneconomical to use undulylarge quantifies. On the other hand, there will be some occasions when it will be both economical and necessary to utilize unusually large proportions ofcrystall-ine tripolyphosphate in the initial phosphate reaction mixtures-such as in the production of very pure products. For example, the so -called,low-temperature form of sodium tripolyphosphate (Na P O --II, discussed in rea detai h r ina n e produced pr ctica ly completely free from impurities (such as insoluble metaphosphates) by making up reaction mixtures containing several times (e.g.', as much as -8 or 10 times). as much crystalline Na P O II as non-tripolyphosphate reactants. I
The times .and temperatures required to convert the various phosphate reaction mixtures described above to tripolyphosphates according to the present invention will depend (somewhat upon the particular tripolyphosphate to be produced and the particular reactantsutilized, as well as upon the proportions and physical -l-state's (-i-.e.,
reactants. In general, the temperatures utilized will be somewhat above 175 C., and preferably above about 200 C.
As already indicated above, the advantages of the present invention may be manifested in one or more of several ways, such as by greater yields of desired product, accelerated rates of reaction, greater degrees of freedom in selection of reaction conditions, etc.
While the present invention is generally applicable to any of the alkali metal tripolyphosphates, it is particularly advantageously utilized in the production of sodium tripolyphosphatesand especially in the production of the so-called low-temperature sodium tripolyphosphate, Na P O -II. (Sodium tripolyphosphate, Na P O is known to be a polymorphic material, of which at least two separate and distinct solid crystalline modifications have been identified. These modifications are commonly referred to as Form I and Form II, and are designated by the formulae, Na P O -I and Na P O II, respectively. See Partridge et al., Journal of the American Chemical Society, vol. 63, page 454 et seq.). Na P O II is generally formed at temperatures below about 470 C., and preferably below about 400 C., whereas Na P O -I is generally formed at temperatures inexcess of about 500? C. Probably because of the lower conversion temperatures utilized, the conversion to Na P O II is somewhat slower than the conversion to Na P O -I, and is also more prone to production of a product having noticeably higher contamination with insoluble impuritiessuch as insoluble metaphosphates. By using the improved process of the present invention, it is possible to effectmarked improvements in both the conversion rate and product purity of Na P O II. Although any of the crystalline forms of sodium tripolyphosphate (for example, Na P O I, Na P O -lLor Na P O -6H O) can be used to improve the production Df N35P3010II, the Na P O 6-I and N35P3010'6H20 are found to be somewhat more effective than N215P3O10II. I I
The following examples are presented as illustrative of various preferred embodiments of the present invention, and as indications of the markedly improved results which can be obtained thereby.
Example I One-tenth gram of powdered Na P O II and 1.9 grams of an equimolar mixture of Na HP,O and NaH P -Na HPO were thoroughly mixed together and heated in an open c'rucible for two hours in a muflle furnace at 200 C. At the same time, 2.0 grams of the equimolar mixture of Na HPOpwith NaI-I PO -Na HPO (but with no-Na P O added) was heated in the same furnace under the same conditions. Subsequent analyses of the reaction products showed that the reaction mass to which five percent of Na P Q II had been added, had been converted to about 45 percent by weight of Na P O whereas the control sample (no Na P O added to reactants) contained only 22 weight percent of S S IO- T i 7 Example 2 Three-tenths gram of powdered K -P O and 2.7 grams of a mixture containing two molesof K HPO with one mole of KH lO were thoroughly mixed together and heated in an open crucible for 30'minutes in a muffle furnace at 300? At the same time, 3.0 grams of the 2:1 K HPO -KH PO mixture was heated in the same furnace under the same conditions. Subsequent analysis of the reaction products showed that the mixture to which K P O had been added had been converted to about 87% by weight of K P 0 whereas the control sample (no K PgO added to the reactants) had been converted to only 66% weight percent K P O I 4 Example 3 Six-tenths grams of Na P O I, was ground to smaller than ZOO-mesh and intimately admixed with 11.4 grams of unground flakes of equimolar proportions of NaH PO 'Na HPO and Na HPO '2H O. This mixture was then divided into 6 equal proportions of 2 grams each and placed in an oven at 250 C. Each sample was left in the oven for a different length time, then withdrawn and analyzed for Na P O II. In this way it was possible to determine the rate of conversion of the phosphate mixtures to sodium tripolyphosphate-II.
The foregoing procedure was repeated except that 0.6 grams of Na P O -6H O was used in place of the 0.6 gram of Na P O -I. The procedure Was also repeated using just the flakes of NaH PO -Na HPO and Na HPO -2H O, without any additional materials.
The results of the foregoing are plotted as the curves of the drawing, and illustrate the marked effect which as little as 5 percent of Na P O I or Na P O -6H O has upon the conversion of phosphate mixtures to Na5P3O o-II.
In the preceding examples the crystalline tripolyphosphate additive was introduced as a solid directly into the solid phosphate mixture which was to be converted to tripolyphosphate product. However, the tripolyphosphate additive can be introduced at earlier stages of the processsuch as during the prepartion of the phosphate mixture which is to be converted. For example, the phosphate mixture utilized in Example 1 can be prepared by evaporating the water from a solution of two mole proportions of disodium orthophosphate and one mole proportion of monosodium'orthophosphate. If the desired amount of crystalline sodium tripolyphosphate additive is dissolved inthis solution prior to evaporation, the solids resulting from the evaporation will contain the necessary crystalline tripolyphosphate for carrying out the process of the present invention.
This application is a continuation-in-part of my earlier copending applications Serial No. 398,725, filed December 17, 1953, now abandoned, and Serial No. 487,221, filed February 9, 1955, now abandoned.
I claim:
1. In the method of producing alkali metal tripolyphosphates by condensation of a mixture of phosphates other than tripolyphosphates at a temperature below the melting point of said tripolyphosphate, said phosphate mixture having an overall molecular ratio of alkali metal oxide to phosphorus pentoxidebetween about 1.5 and about 1.8 and an overall molecular ratio of alkali metal oxide to water of constitution less than about 10, the improvement which comprises adding at least 1 percent by weight of crystalline alkali metal tripolyphosphate to said mixture of phosphates, thereby accelerating the rate of conversion of said mixture of phosphates to said alkali metal tripolyphosphate.
2. The method of claim 1, wherein the alkali metal tripolyphosphate is sodium tripolyphosphate.
V 3. The method of claim 1, wherein the alkali metal tripolyphosphate is potassium tripolyphosphate.
4. In the method of producing sodium tripolyphosphate by condensation of an approximately 2:1 molar mixture 'of disodium orthophosphate and monosodium orthophosphate, said mixture of orthophosphates having an over-all molecular ratio of sodium oxide to phosphorus pentoxide between about 1.5 and about 1.8 and an overall molecular ratio of sodium oxide to water of constitution less than about 10, said condensation being carried outat a temperature below the melting point of said tripolyphosphate,'the improvement'which comprises adding at least 1 percent by weight of crystalline sodium tripolyphosphate to said mixture of orthophosphates, thereby accelerating the rate of conversion of said mixture of orthophosphates tosaid sodium tripolyphosphate.
5. The process of claim 4, wherein the amount of crystalline sodium tripolyphosphate added to said mixture of orthophosphates is at least about 2 percent by weight.
6. The method of producing sodium tripolyphosphate- II, which comprises adding at least 1 percent by weight ofa compound selected from the group consisting of sodium tripolyphosphate hexahydrate and sodium tripolyphosphate-I to a mixture of sodium phosphates other than sodium tripolyphosphate containing at least 10 percent by weight of orthophosphate and having an overall molecular ratio of Na O:P O between about 1.5 and about 1.8 and an overall molecular ratio of Na Ozwater of consti- References Cited in the file of this patent UNITED STATES PATENTS 2,419,148 King Apr. 15, 1947 2,493,809 Garrison Jan. 10, 1950 2,737,443 Wright Mar. 6, 1956 2,776,187 Pfengle Jan. 1, 1957
Claims (1)
1. IN THE METHOD OF PRODUCING ALKALI METAL TRIPOLYPHOSPHATES BY CONDENSATION OF A MIXTURE OF PHOSPHATES OTHER THAN TRIPOLYPHOSPHATES AT A TEMPERATURE BELOW THE MELTING POINT OF SAID TRIPOLYPHOSPHATE, SAID PHOSPHATE MIXTURE HAVING AN OVERALL MOLECULAR RATIO OF ALKALI METAL OXIDE TO PHOSPHORUS PENTOXIDE BETWEEN ABOUT 1.5 AND ABOUT 1.8 AND AN OVERALL MOLECULAR RATIO OF ALKALI METAL OXIDE TO WATER OF CONSTITUTION LESS THAN ABOUT 10, THE IMPROVEMENT WHICH COMPRISES ADDING AT LEAST 1 PERCENT BY WEIGHT OF CRYSTALLINE ALKALI METAL TRIPOLYPHOSPHATE TO SAID MIXTURE OF PHOSPHATE, THEREBY ACCELERATING THE RATE OF CONVERSION OF SAID MIXTURE OF PHOSPHATES TO SAID ALKALI METAL TRIPOLYPHOSPHATE.
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US640256A US2920939A (en) | 1957-02-14 | 1957-02-14 | Method of producing phosphates |
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US640256A US2920939A (en) | 1957-02-14 | 1957-02-14 | Method of producing phosphates |
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Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3030180A (en) * | 1958-01-28 | 1962-04-17 | Saint Gobain | Manufacture of sodium tripolyphosphate |
US3056652A (en) * | 1957-11-26 | 1962-10-02 | Lever Brothers Ltd | Modification of the hydration characteristics of form ii sodium tripolyphosphate prior to detegent processing |
US3094382A (en) * | 1957-12-04 | 1963-06-18 | Saint Gobain | Preparation of sodium tripolyphosphate |
US3110559A (en) * | 1957-12-03 | 1963-11-12 | Saint Gobain | Preparation of sodium tripolyphosphate |
US3160472A (en) * | 1960-05-06 | 1964-12-08 | Monsanto Co | Agglomeration of powdered tripolyphosphates |
US3210154A (en) * | 1962-03-07 | 1965-10-05 | Stauffer Chemical Co | Molecularly dehydrated phosphates |
US3233968A (en) * | 1961-04-25 | 1966-02-08 | Marchon Products Ltd | Manufacture of condensed phosphates |
US3361523A (en) * | 1963-03-19 | 1968-01-02 | Monsanto Co | Method for producing phosphates |
US3423321A (en) * | 1964-07-17 | 1969-01-21 | Monsanto Co | Detergent processes |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2419148A (en) * | 1944-08-16 | 1947-04-15 | Blockson Chemical Co | Manufacture of sodium triphosphates |
US2493809A (en) * | 1946-01-18 | 1950-01-10 | Texaco Development Corp | Manufacture of polyphosphates |
US2737443A (en) * | 1952-06-17 | 1956-03-06 | Monsanto Chemicals | Process for the production of stabilized sodium acid pyrophosphate |
US2776187A (en) * | 1950-09-08 | 1957-01-01 | Chem Fab Budenheim Ag | Production of tripolyphosphates |
-
1957
- 1957-02-14 US US640256A patent/US2920939A/en not_active Expired - Lifetime
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2419148A (en) * | 1944-08-16 | 1947-04-15 | Blockson Chemical Co | Manufacture of sodium triphosphates |
US2493809A (en) * | 1946-01-18 | 1950-01-10 | Texaco Development Corp | Manufacture of polyphosphates |
US2776187A (en) * | 1950-09-08 | 1957-01-01 | Chem Fab Budenheim Ag | Production of tripolyphosphates |
US2737443A (en) * | 1952-06-17 | 1956-03-06 | Monsanto Chemicals | Process for the production of stabilized sodium acid pyrophosphate |
Cited By (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3056652A (en) * | 1957-11-26 | 1962-10-02 | Lever Brothers Ltd | Modification of the hydration characteristics of form ii sodium tripolyphosphate prior to detegent processing |
US3110559A (en) * | 1957-12-03 | 1963-11-12 | Saint Gobain | Preparation of sodium tripolyphosphate |
US3094382A (en) * | 1957-12-04 | 1963-06-18 | Saint Gobain | Preparation of sodium tripolyphosphate |
US3030180A (en) * | 1958-01-28 | 1962-04-17 | Saint Gobain | Manufacture of sodium tripolyphosphate |
US3160472A (en) * | 1960-05-06 | 1964-12-08 | Monsanto Co | Agglomeration of powdered tripolyphosphates |
US3233968A (en) * | 1961-04-25 | 1966-02-08 | Marchon Products Ltd | Manufacture of condensed phosphates |
US3210154A (en) * | 1962-03-07 | 1965-10-05 | Stauffer Chemical Co | Molecularly dehydrated phosphates |
US3361523A (en) * | 1963-03-19 | 1968-01-02 | Monsanto Co | Method for producing phosphates |
US3423321A (en) * | 1964-07-17 | 1969-01-21 | Monsanto Co | Detergent processes |
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