Method for preparing phosphorus-chlorine compounds from phosphorus-oxygen compound-containing materials

Abstract

The invention relates to a method for producing phosphorus-chlorine compounds, characterized in that i. A material containing phosphorus oxides is reacted in the presence of tetrachloroethylene at a temperature of 500 DEG C to 1000 DEG C, and ii. The formed phosphorus-chlorine compounds, in particular phosphoryl chloride, are withdrawn and separated from an exhaust gas stream.

Description

[0001] This invention relates to a method for converting materials containing phosphorus oxides into at least one phosphorus chloride compound. These can then be sent for industrial use.

[0002] Phosphate digestion (primarily water-insoluble) plays a vital role in analysis and technology, aiming for industrially and economically viable utilization or quantification of phosphorus compounds. In analysis, it is used to determine phosphorus in rocks or ores. Calcium phosphate sources are industrially reacted in large quantities with sulfuric acid to obtain water-soluble phosphoric acid, which is primarily used as a fertilizer or detergent additive, and secondarily as an acidifying agent, for example, in the food industry.

[0003] Phosphate / phosphoric acid is industrially obtained by lowering the pH of an aqueous slurry of ground phosphate rock (preferably by means of an inorganic acid such as sulfuric acid or phosphoric acid), followed by filtration. The disadvantage of this method is that it requires very large quantities of acid, and the filtration step, with its corresponding byproducts that are difficult to control industrially, is absolutely necessary. This also generates a significant amount of waste.

[0004] However, these reactions do not produce the desired phosphorus and chloride compounds.

[0005] On an industrial scale, phosphorus-chloride compounds are prepared only through an energy-intensive and cumbersome circuitous route via the synthesis of elemental phosphorus and subsequent reaction with elemental chlorine.

[0006] On an industrial scale, phosphorus-chloride compounds are typically obtained through a route that produces elemental phosphorus in an electric arc furnace from phosphate rock, coal, and admixtures, followed by the combustion of phosphorus with chlorine to produce phosphorus-chloride compounds. The disadvantages here include very high energy consumption, high temperatures, handling of toxic white phosphorus, handling of arsenic compounds, handling of toxic chlorine, handling of extremely large quantities of slag, and a very large CO2 footprint.

[0007] However, only phosphorus chlorides such as PCl3 can be obtained in this way. Phosphoryl chloride POCl3 cannot be obtained in this way and must be produced only through oxidation from PCl3 in a further step.

[0008] A method for directly obtaining phosphorus chloride compounds as volatile compounds from phosphates uses carbon tetrachloride, partially combined with chlorine and / or with an inert gas such as carbon dioxide. This involves heating the sample to 700°C to 900°C and passing a gas stream over it. The gas stream is then directed into a scrubber, where the phosphate is studied. Quantitative conversions have been reported and this method has been tested on many metal phosphates (Jannasch, P., Jilke, W.; Journal für praktische Chemie , 21, 1908 and Jannasch P., Jilke, W.;Journal für praktische Chemie , 113, 1909).

[0009] The described long reaction time is a drawback of this method. However, most importantly, the use of carbon tetrachloride in industrial processes has been banned because this compound damages the ozone layer, making this reaction industrially impossible.

[0010] Purpose

[0011] Therefore, the object of the present invention is to find a method for preparing phosphorus chloride compounds that no longer suffers from the disadvantages of the prior art described herein. Surprisingly, a method for preparing phosphorus chloride compounds, particularly phosphoryl chlorides, has been discovered, characterized in that...

[0012] i. Reacting a phosphorus-containing oxide material in the presence of tetrachloroethylene at a temperature of 500°C to 1000°C, preferably 600°C to 900°C, and particularly 700°C to 850°C, and

[0013] ii. The resulting phosphorus and chloride compounds, especially phosphoryl chlorides, are extracted and separated from the waste gas stream.

[0014] Preferably, the phosphorus chloride compound phosphoryl chloride is prepared using the method according to the present invention.

[0015] Phosphorus oxides

[0016] Various phosphorus oxide-containing materials can be used. For example, the phosphorus oxide-containing material may contain at least one phosphorus oxide selected from the group consisting of: inorganic alkali metal and / or alkaline earth metal salts of phosphorus oxides, their phosphates, especially calcium phosphates, apatite, especially chloroapatite or hydroxyapatite, sodium phosphates, ferric phosphates, aluminophosphates, lithium iron phosphates, especially lithium iron phosphate or lithium iron manganese phosphate, or phosphonic acid, phosphoric acid, their respective polybasic acids or anhydrides, or mixtures thereof.

[0017] Preferably, the phosphorus-containing material contains calcium phosphates, particularly their corresponding orthophosphates, metaphosphates, or polyphosphates, or mixtures thereof. Particularly preferred calcium phosphates are calcium phosphates, particularly calcium orthophosphate or metaphosphate, calcium hydroxyapatite, or mixtures thereof.

[0018] Preferably, the phosphorus-containing oxide material contains at least one inorganic phosphate, particularly the corresponding orthophosphate, metaphosphate, or polyphosphate, or a mixture thereof. Particularly preferably, it contains calcium phosphate, especially calcium orthophosphate or calcium hydroxyapatite.

[0019] The phosphorus-containing oxide material preferably contains at least one phosphorus oxide, the content of which, calculated by elemental phosphorus, is 1% to 44% by weight, preferably 1% to 30% by weight, and particularly 5% to 28% by weight.

[0020] Another preferred method is one in which the phosphorus-containing oxide material is sludge ash or a black substance containing iron phosphate.

[0021] Sludge ash is preferably understood to refer to the solid residues produced during sludge combustion and sludge gasification for the production of fuel gases. Sludge ash may contain various components, such as preferably aluminosilicates, ferric phosphates like calcium ferric phosphate (e.g., Ca9Fe(PO4)7 or white calcium phosphate Ca3(PO4)2), gypsum, calcium hydroxides, calcium oxides and calcium carbonates, iron oxides such as hematite (Fe2O3), quartz (SiO2), and indialites (Mg2Al4Si5O3). 18 (This is just a list of a few.)

[0022] The sludge ash preferably contains a certain proportion of phosphorus oxides, particularly phosphates, with a phosphorus content of 1.5% to 13.1% by weight based on the phosphorus-containing material, preferably 1% to 21% by weight (based on elemental iron) of iron compounds, and 0.7% to 20.2% by weight (based on elemental aluminum) of aluminum compounds, in each case also based on the phosphorus-containing material. Preferably, the total amount of iron and aluminum compounds is 1.7% to 41.2% by weight based on the corresponding elemental metal.

[0023] Sludge ash may typically contain other typical elements, and preferably, based on the corresponding elements, the following:

[0024] Calcium content ranges from 4% to 38% by weight.

[0025] Potassium content of 0% to 2% by weight,

[0026] Magnesium, by weight, from 0.1% to 4%.

[0027] Sodium content of 0.1% to 4% by weight.

[0028] Sulfur content of 0% to 7% by weight.

[0029] Silicon and by weight 0% to 24%

[0030] 0% to 2% titanium by weight.

[0031] These elements, calculated as oxides, preferably account for more than 70% by weight of sludge ash.

[0032] The corresponding components may preferably be in the form of oxides, phosphates, or sulfates. Iron compounds are preferably in the form of 50%-100% by weight of iron(III) compounds. Preferably, 80% or more by weight of phosphates are in the form of aluminum, calcium, or iron metal phosphates. In addition, sludge ash may also contain trace amounts of many other elements, particularly copper, zinc, lead, barium, and manganese. The aforementioned silicon is essentially in the form of sand, primarily derived from conventional filtration processes in wastewater treatment plants.

[0033] The phosphorus-containing oxide material may preferably consist of 100% iron phosphate compound, or may contain only a portion of such iron phosphate compound. Preferably, the material used contains an iron phosphate compound whose total content, calculated on an elemental phosphorus basis, is 1% to 22% by weight, preferably 10% to 21% by weight, based on the phosphorus-containing oxide material. Preferably, the material used contains at least one iron phosphate compound selected from the group consisting of: iron phosphates, particularly iron(II), iron(III), and iron(III) pyrophosphate, lithium iron phosphate (LFP), lithium iron manganese phosphate (LFMP), and particularly those having the general formula LiFe. (1-x) Mn x LFP and / or LFMP of PO4, where 0 ≤ x < 0.9, particularly 0 ≤ x < 0.6, or mixtures thereof.

[0034] Preferably, the material contains LFP and / or LFMP, and more preferably contains LiFe (as shown in the formula above). 1-x Mn x PO4. Therefore, the method according to the invention particularly uses materials containing 2% to 100% by weight, preferably 40% to 99% by weight, particularly 50% to 99% by weight, and especially preferably 70% to 99% by weight of LFP and / or LFMP. Preferably, the composition of the material used can also be described by determining the weight fraction of certain elements in the preferred LFP and / or LFMP-containing material used, in each case based on the amount of material, wherein the material used preferably contains:

[0035] Fe content ranging from 1% to 36% by weight,

[0036] The preferred amount of elemental phosphorus, calculated by weight, is 0.4% to 20%, based on materials containing LFP and / or LFMP.

[0037] Mn, by weight, from 0% to 35%

[0038] 1% to 8% by weight of Li and

[0039] Carbon, by weight, from 1% to 55%, preferably from 1% to 40%, and particularly from 1% to 30%. These amounts of the element may be derived from LFP or LFMP, but may also be derived from other components of the material used, such as residues from metallic components.

[0040] The elemental content is preferably determined using conventional elemental analysis methods. The type and amount of present iron phosphate compounds are preferably determined by X-ray scattering XRD on Cu-K atoms. α The method of reflecting the powder under radiation is used to determine the phase. The obtained reflection is compared with, for example, data from ICDD (International Center for Diffraction Data), and assigned to the obtained iron phosphate phase.

[0041] For lithium iron phosphate, the reflectance of JCPDS (International Center for Powder Diffraction Data) card #83-2092 is used for comparison. Preferably, the material used further contains 1% to 55% by weight, preferably 1% to 40% by weight, and particularly 1% to 30% by weight of carbon, especially graphite and / or carbon black. Preferably, in the material used which preferably contains LFP and / or LFMP, the total amount of LFP and / or LFMP with carbon is greater than 70% by weight, preferably greater than 80% by weight, and particularly preferably greater than 90% by weight. Battery cells containing LFP and / or LFMP are generally mechanically crushed as much as possible, and the remainder containing cathode and anode materials, any binders, and other components is pulverized to form a black substance, which is referred to as "black substance" because LFP / LFMP and graphite-containing anode materials are dark in color. Due to technical incomplete separation, the black substance may also contain residues of other battery components, such as metals.

[0042] Therefore, phosphorus-containing oxide materials can also be so-called black substances, with the proportion of phosphate compounds calculated by elemental phosphorus ranging from 0.4% to 21% by weight based on phosphorus-containing oxide materials.

[0043] The materials used may also contain preferably 0% to 15% by weight, preferably 0% to 5% by weight of metals; in particular, Al, Cu, Co and Ni may be present.

[0044] The aluminum content of the materials used is preferably less than 10% by weight, and particularly less than 5% by weight, as determined by elemental aluminum.

[0045] The preferred materials used contain less than 10% by weight, particularly less than 1% by weight, especially less than 0.1% by weight of polymer particles, particularly plastics such as polyethylene and / or polypropylene.

[0046] The materials used, which contain LFP and / or LFMP, are preferably black substances derived from battery pulverization.

[0047] The materials or phosphorus oxides used preferably have an average particle size of 0.1 μm to 50 mm, more preferably 0.5 to 10 mm. Depending on the size, the particle size can be readily determined by sieving, or for smaller particles, by laser diffraction or laser scattering. The best method to be used in each case is known to those skilled in the art. The materials used, preferably containing LFP and / or LFMP, can also be coated materials. The coating materials preferably include carbon, especially graphite and metal oxides.

[0048] The moisture content of the phosphorus oxides or materials used is preferably less than 5% by weight, and in particular less than 1% by weight.

[0049] method

[0050] This reacts materials containing phosphorus oxides in the presence of tetrachloroethylene. It can be used as is or as its precursor chloroform, which eliminates HCl and converts to tetrachloroethylene at temperatures of 500°C and above, or as a mixture containing tetrachloroethylene and chloroform.

[0051] Since the thermal conversion of chloroform to tetrachloroethylene is accompanied by the formation of HCl, and HCl is useless for further reactions with phosphorus oxides, tetrachloroethylene is preferred as a reactant, provided that it is available.

[0052] The reaction may optionally be carried out in the presence of an inert gas. Suitable inert gases include, for example, nitrogen, carbon dioxide, and / or argon. Based on the total amount of gas streams containing these components, tetrachloroethylene, optionally used with chloroform and optionally with a carrier gas, preferably contains an oxygen content of less than 0.1%, particularly less than 0.05% by volume. Preferred inert gases used are nitrogen, carbon dioxide, or argon.

[0053] Preferably, the weight ratio of the total amount of tetrachloroethylene and / or chloroform to the inert gas is between 1:0 and 1:6, more preferably between 1:0 and 1:4.

[0054] The reaction of phosphorus-containing oxide materials is preferably carried out in fluidized bed, packed bed, or moving bed reactors, in vertical furnaces or furnaces (such as those conceived in their simplest form as indirect heating tube furnaces or rotary tube furnaces). Each reactor is preferably airtight. The material may also optionally be shaped, for example by briquetting, extrusion, or granulation, before being introduced into the furnace. For this purpose, additives such as layered silicates, particularly bentonite, as well as lignosulfonates, methylcellulose, water glass, starch, or other additives can be used.

[0055] Preferably, the phosphorus-containing oxide material to be used according to the method of the invention is introduced into the reactor, which is preferably provided with a layer resistant to the reaction conditions to be established. Preferred reactor materials are nickel- or graphite-coated reactors. Particularly preferred are reactors that allow material movement during the reaction to allow for the most efficient contact and heat distribution of the reactants possible. Fluidized bed equipment and rotating tubular reactors are preferred, or the reaction may take place in an extruder with screw propulsion.

[0056] In the case of a tubular reactor, the reactor length is preferably 0.2 to 40 m. The residence time in the reactor during the reaction is generally determined by the temperature and the likelihood of contact between the reactants. The method according to the invention can be carried out in batches or continuously.

[0057] A gas stream of tetrachloroethylene and / or chloroform (optionally diluted with an inert carrier gas stream) is preferably directed through the reactor and over the phosphorus oxides or over the material containing them, while the reaction temperature is maintained at 500°C to 1000°C, preferably 600°C to 900°C, and particularly 700°C to 850°C. The reaction time can range from a few minutes to 10 hours, preferably between 20 minutes and 5 hours.

[0058] For each mole of phosphorus-containing oxide material, the phosphorus is preferably 0.75 to 4 mol of tetrachloroethylene or 1 to 4.5 mol of chloroform.

[0059] Products formed during the reaction and which may be volatile at the reaction temperature, in particular phosphoryl chloride, ferric chloride, and also aluminum chloride and optional other heavy metal chlorides such as zinc chloride or rare earth chlorides, are preferably sublimated from the exhaust stream at different cooling sites and collected separately.

[0060] The preferred deposition temperature of FeCl2 is below 701°C, particularly below 700°C to 307°C; the preferred deposition temperature of FeCl3 is below or equal to 307°C, particularly 150°C to 300°C; and the preferred deposition temperature of AlCl3 is below or equal to 150°C, particularly 110°C to 149°C.

[0061] Phosphoryl chloride is preferably collected in a condenser at a temperature preferably below 110°C.

[0062] Sublimes and residues are both substantially water-soluble and can preferably be further separated and isolated from their aqueous solutions, for example, after their possible presence has been determined by conventional H2S separation procedures, they can be separated and isolated from each other in the form of their sulfides, chlorides, phosphates, fluorides or other precipitated compounds.

[0063] Examples

[0064] analyze

[0065] After dissolving the calcium phosphate sample in a suitable acid, calibrating it with the corresponding elemental calibration standard solutions, and then analyzing it in ICP-OES.

[0066] Example 1

[0067] 10 g of industrial-grade calcium phosphate (obtained from sludge ash treatment) containing (by weight %) Ca: 35%, PO4: 52%, Fe: 0.14%, Al: 0.48% as determined by ICP-OES, was introduced into a quartz reactor (120 mm diameter) placed in a tubular furnace. The reactor was heated to 150°C.

[0068] Tetrachloroethylene at a flow rate of 0.2 ml / min was evaporated in a total evaporator and mixed with a nitrogen stream of 1 l / min at 150°C. The tetrachloroethylene and nitrogen mixture entered a quartz reactor and passed over calcium phosphate, which was heated to 150°C to prevent reactant condensation. The gaseous reaction products exited the reactor as a waste gas stream, which was cooled to 100°C and guided through a gas chamber with an optical window through which the infrared spectrum of the gas phase was recorded. Heating in this stage of the reaction was specifically designed to prevent condensation of both reactants and products.

[0069] Therefore, the solid was heated to 780°C in the reactor and gas flow over a period of 2 hours, while the exhaust gas flow was continuously observed by recording IR spectra.

[0070] The sample can also be heated to 780°C before adding tetrachloroethylene.

[0071] At temperatures of 750°C and above, the reaction to form POCl3 becomes rapid, as evidenced by the band observed in the IR spectrum (592 cm⁻¹). -1 (P-Cl), 1322 cm -1 (P=O), Reference: 590 cm -1 and 1322 cm -1 (± 6 cm -1), Shimanouchi, T., Tables of Molecular Vibrational Frequencies Consolidated Volume II, J. Phys. Chem. Ref. Data, 1972, 6, 3, 993-1102.

[0072] POCl3 is collected in the condenser.

[0073] After the reaction was complete, 13.2 g of a black solid, composed primarily of CaCl2 and partially melted, was obtained. This solid reaction product can be dissolved in water and sent for further uses, such as phosphate precipitation in wastewater treatment plants.

[0074] Example 2

[0075] 50 g of industrial-grade calcium phosphate (obtained from sludge ash treatment) containing (by weight %) Ca: 35%, PO4: 52%, Fe: 0.14%, Al: 0.48% as determined by ICP-OES, was introduced into a quartz reactor (120 mm diameter) placed in a tubular furnace. The reactor was heated to 150°C.

[0076] 0.2 ml / min of chloroform was evaporated in a total evaporator and mixed with a nitrogen stream of 1 l / min at 100°C. The chloroform and nitrogen mixture entered a quartz reactor and passed over calcium phosphate, which was heated to 150°C to prevent condensation of the reactants. The gaseous reaction products exited the reactor, were cooled to 100°C, and guided through a gas chamber with an optical window through which the infrared spectrum of the gas phase was recorded. Heating in this stage of the reaction was specifically designed to prevent condensation of both reactants and products.

[0077] Therefore, the solid was heated to 780°C in the reactor and gas flow over a period of 2 hours, while the exhaust gas flow was continuously observed by recording IR spectra.

[0078] The sample can also be heated to 780°C before adding chloroform.

[0079] At temperatures of 500°C and above, chloroform decomposes into HCl and tetrachloroethylene.

[0080] At temperatures of 600°C and above, the formed tetrachloroethylene reacts increasingly rapidly with the initially added calcium phosphate, producing calcium chloride and phosphoryl chloride. POCl3 is collected in a condenser. The latter can be identified by characteristic bands in the infrared spectrum. At 750°C and above, the reaction reaches a rate at which significant conversion can be achieved. The reaction is terminated 20 minutes after reaching the target temperature of 780°C.

Claims

1. A method for preparing phosphorus-chloride compounds, characterized in that, i. Reacting a phosphorus-containing oxide material in the presence of tetrachloroethylene at a temperature of 500°C to 1000°C, and ii. The resulting phosphorus and chloride compounds, especially phosphoryl chloride, are extracted and separated from the waste gas stream.

2. The method for preparing phosphorus chloride compounds according to claim 1, characterized in that, The reaction is carried out at temperatures between 600°C and 900°C, particularly between 700°C and 850°C.

3. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 2, characterized in that, The phosphorus-chlorine compound is phosphoryl chloride.

4. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 3, characterized in that, The phosphorus-containing material contains at least one phosphorus-containing compound selected from the group consisting of: phosphates, especially calcium phosphates, apatite, especially chloroapatite or hydroxyapatite, sodium phosphates, ferric phosphates, aluminophosphates, lithium iron phosphates, especially lithium iron phosphate or lithium iron manganese phosphate, or phosphonic acid, phosphoric acid, their respective polyacids or anhydrides, or mixtures thereof.

5. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 4, characterized in that, The phosphorus-containing oxide material contains at least one inorganic phosphate, particularly the corresponding orthophosphate, metaphosphate, or polyphosphate, or a mixture thereof.

6. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 5, characterized in that, The phosphorus-containing oxide material contains calcium phosphate, with calcium orthophosphate, calcium metaphosphate and / or calcium hydroxyapatite being particularly preferred.

7. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 6, characterized in that, The phosphorus-containing oxide material contains at least one phosphorus oxide, the content of which, calculated by elemental phosphorus, is 1% to 44% by weight, preferably 1% to 30% by weight, and particularly 5% to 28% by weight.

8. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 7, characterized in that, The material containing phosphorus oxides is sludge ash or a black substance containing iron phosphate.

9. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 8, characterized in that, The phosphorus-containing oxide material has an average particle size of 0.1 μm to 50 mm, preferably 0.5 to 10 mm.

10. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 9, characterized in that, Tetrachloroethylene and / or chloroform may optionally be used together with an inert gas in the reaction of the phosphorus oxide-containing material.

11. The method for preparing phosphorus chloride compounds according to at least one of claims 1 to 10, characterized in that, Phosphoryl chloride is drawn from the waste gas and separated by condensation—preferably at a temperature below 110°C.