CN101774562B - One pot method prepares the method for crystalline V-type ammonium polyphosphate - Google Patents

Abstract

In the invention, a crystal form V ammonium polyphosphate product is prepared by crystal form controllable high temperature polymerization technology with one or more than one of ammonium dihydrogen phosphate, diammonium hydrogen phosphate and ammonium phosphate as the main raw material and amine-containing substances as the condensing agent. The key of the crystal form controllable high temperature polymerization technology is ammonia atmosphere introduction and program temperature rising process control. Wet ammonia is introduced, and after the reaction system is totally neutralized by the wet ammonia atmosphere, controllable conversion toward crystal form V is realized by wet ammonia environment and program temperature control. The invention overcomes corrosivity of reactants on material in high temperature environment, all the reactions are completed once and for all in a kneader, and the production flow is simplified.

Description

One pot method prepares the method for crystalline V-type ammonium polyphosphate

【Technical field】

The invention relates to the technical field of ammonium polyphosphate preparation, in particular to a method for preparing crystalline V-type ammonium polyphosphate in one pot.

【Background technique】

The preparation methods of crystalline V-type ammonium polyphosphate mainly fall into two categories: one is to use type I and type II ammonium polyphosphate as raw materials to realize crystal transformation under certain conditions; the other is high-temperature polymerization of phosphoric acid or ammonium phosphate.

U.S. Patent US3687695 proposes that I-type, II-type ammonium polyphosphate and their mixtures are heated to 340-420°C, heat-treated in a high ammonia-containing atmosphere, and then rapidly cooled to obtain ammonium polyphosphate whose crystal form is V-type. The conversion condition is that the partial pressure of ammonia is at least 0.63MPa, and when the I-type structure is transformed into a V-type structure, it is cooled rapidly. The cooling rate is higher than 50°C/min, especially at 250-350°C. Up to 75°C/min, which can only be achieved with liquid nitrogen cooling. This method needs to be quenched at high temperature, the operating conditions are harsh, it is difficult to realize and the energy consumption is extremely high.

Japanese patent JP09235110 proposes that phosphate (such as ammonium phosphate) and condensing agent (such as urea) are heated and condensed at 300-380°C in the presence of wet ammonia to form V-type ammonium polyphosphate; this patent requires ammoniation The condition must be in a wet ammonia atmosphere, and the product purity is related to the water content of the atmosphere, otherwise the obtained product is type I APP by XRD analysis. The reaction temperature required by the ammonium phosphate thermal condensation method is relatively high, close to 400°C, which takes several hours, and the high-temperature melting stage in the early stage is very corrosive to the equipment, requiring anti-corrosion reaction equipment with special materials.

In the invention patent application 200910195527.3 proposed by Liu Gousheng et al., monoammonium phosphate and urea with a molar ratio of 0.8:1 to 1.5:1 were selected as raw materials, and the temperature was continuously raised to 360 to 400°C in the reactor for 1 to 2 hours. , dry ammonia gas is passed into the reactor, the partial pressure of ammonia gas is 0.02-0.04Mpa, the flow rate of ammonia gas is 1-1.5L/min, the temperature in the reactor is 360-400°C, the reaction time is maintained for 0.75-1.5 hours, and finally it is cured, Crushed and discharged to obtain crystalline V-type ammonium polyphosphate. The corrosion of the equipment in the early high-temperature melting stage of this method is relatively serious, and anti-corrosion reaction equipment with special materials is required.

The invention patent application 200910199096.8 proposed by Liu Gousheng et al. selects phosphoric acid and melamine with a molar ratio of 1:1/6 to 1:1/8 as raw materials. After dehydrating phosphoric acid (85%), a condensing agent is added to the reactor , continue to heat up to 280-330°C, maintain for 5-30min, pass dry ammonia gas into the reactor, ammonia gas partial pressure 0.02-0.04Mpa, ammonia gas flow rate 0.3-1.0L/min, maintain ammoniation time 15-60min, Finally, the crystalline V-type ammonium polyphosphate is obtained through solidification, crushing and discharging. Similarly, the corrosion of equipment in the early high temperature stage of this method is relatively serious, requiring anti-corrosion reaction equipment with special materials.

Generally, the enamel reaction kettle is in the high-temperature polyphosphate medium, and is affected by the strong acid medium formed by the release of ammonia from the phosphate at high temperature. Higher concentration of phosphoric acid and polyphosphoric acid medium, but due to the great difference in thermal expansion coefficient between the polytetrafluoroethylene material and the outer wall steel, the maximum operating temperature of the reactor lined with polytetrafluoroethylene material cannot exceed 250 °C, if the temperature is too high, the inner The lining PTFE and the outer wall steel are bubbling and falling off. Ordinary 304 stainless steel, SUS316L stainless steel, and Hastelloy B, C, and G series have all been corroded after testing. Therefore, although the production process of the above-mentioned invention is feasible, industrialization is all faced with the restriction of equipment materials. In order to meet the requirements of large-scale industrial production, it is necessary to improve the production method of crystalline V-type ammonium polyphosphate in terms of production technology.

【Content of invention】

The purpose of the present invention is to overcome the deficiencies in the prior art, and a kind of one-pot method is provided to prepare the method for crystalline V-type ammonium polyphosphate.

The implementation method of the present invention is, in the kneader of ordinary 304 stainless steel or better 316L stainless steel as material, add one, any two or three mixtures of ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate , and add amine-containing condensing agent at the same time. The amine-containing condensing agent is one or more of urea, biuret, methylurea, amidinourea, biuret, ammonium carbonate, cyanuric acid, and melamine. mixture. First, the material is melted and pre-polymerized at a lower reaction temperature, and a certain amount of wet ammonia gas is continuously introduced during the process. After a period of reaction, the wet ammonia is continued to ensure that the reaction material is completely neutralized by the wet ammonia gas. , heat up to a higher temperature, and the wet ammonia environment is conducive to high temperature conditions to achieve a controllable transformation to crystal V-type, and then continue to heat and mature for a period of time in a wet ammonia environment, cool and discharge, and pulverize to obtain crystal V-type ammonium polyphosphate .

The present invention is realized through the following technical solutions, and its concrete steps are:

(1) In a kneader made of ordinary 304 stainless steel or better 316L stainless steel, add one, any two or three mixtures of ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate, and add the mixture containing Amine condensing agent, heating to 160-240°C to melt the material, during which wet ammonia gas containing a certain amount of water is introduced into the system, the flow rate of wet ammonia gas is 0.05-3.0L/min/kg, and the temperature is maintained at 180-240°C. And keep it warm for 5-60 minutes; the temperature for adding the condensing agent is between room temperature and 280°C.

(2) Rapidly raise the temperature to 250-350°C, and continuously feed wet ammonia gas containing a certain amount of water during this process, the flow rate of wet ammonia gas is 0.05-3.0L/min/kg, and keep the material in a state of agitation all the time to maintain the temperature 250-350°C, and keep warm for 20-60 minutes;

(3) Continue to feed wet ammonia gas, the flow rate of wet ammonia gas is 0.05-3.0L/min/kg, maintain the temperature at 200-320°C, and keep it for 30-120 minutes, cool and discharge, crush, and you can get crystal V type ammonium polyphosphate;

The amine-containing condensing agent is one or a mixture of urea, biuret, methylurea, guanylurea, biuret, ammonium carbonate, cyanuric acid, and melamine. The weight of ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate is 100kg, and the weight of the amine-containing condensing agent is 0.5-50kg. The wet ammonia atmosphere is made by passing ammonia gas into 0%-29% ammonia solution, and the water vapor content in the prepared wet ammonia gas is 0%-30%.

The present invention uses a D/MAX 2550 VB/PC polycrystalline X-ray diffractometer to characterize the structure of the prepared product, at a scanning speed of 2-4° per minute, and collects diffraction data within a scanning range of 10-80°.

Compared with prior art, positive effect of the present invention is:

(1) The present invention uses one or more of ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and ammonium orthophosphate as the main raw material, with amine-containing substances as the mixed condensation agent, and through the high-temperature polymerization technology with controllable crystal form, The obtained crystalline V-type ammonium polyphosphate product belongs to the non-phosphorus pentoxide raw material route, which meets the needs of enterprises for energy saving and emission reduction and industrial structure adjustment of the phosphorus chemical industry.

(2) The core of the crystal form controllable technology of the present invention is the ammonia atmosphere and the temperature programming process control. After using wet ammonia and ensuring that the reaction system is completely neutralized by the wet ammonia atmosphere, the wet ammonia environment and program temperature control can realize the controllable transformation from amorphous to crystalline V-type. The invention overcomes the corrosivity of the reaction material to the material under the high-temperature environment, can use ordinary 304 stainless steel or better 316L stainless steel as the material, and completes all reactions in a kneader once, which simplifies the production process.

【Description of drawings】

The XRD collection of illustrative plates of Fig. 1 preparation product of the present invention;

【Detailed ways】

The specific implementation of the method for preparing crystalline V-type ammonium polyphosphate by one-pot method of the present invention is provided below.

Example 1

In a kneader made of ordinary 304 stainless steel, add 100 kg of ammonium dihydrogen phosphate, and at the same time add 12 kg of urea and 5 kg of ammonium carbonate as a mixed condensing agent, and the temperature of adding the condensing agent is room temperature. Heat to 180°C to melt the material, during which wet ammonia gas containing 20% water is introduced into the system, the flow rate of wet ammonia gas is 40L/min, keep the temperature at 190°C, and keep it warm for 30 minutes; quickly raise the temperature to 290°C, at this During the process, continuously feed wet ammonia gas containing 8% moisture, the flow rate of wet ammonia gas is 100L/min, and keep the material in a stirring state, keep the temperature at 310°C, and keep it warm for 40 minutes; continue to feed wet ammonia gas containing 10% moisture Ammonia gas, wet ammonia gas flow rate 20L/min, maintain the temperature at 260°C for 60 minutes, cool and discharge, crush to obtain crystalline V-type ammonium polyphosphate.

Example 2

In a kneader made of 316L stainless steel, add 100kg of diammonium hydrogen phosphate, 3kg of urea and 5kg of biuret at the same time, heat to 180°C to melt the material, and add the condensing agent at a temperature of 180°C. During this period, wet ammonia gas containing 15% moisture was fed into the system, the flow rate of wet ammonia gas was 40L/min, and the temperature of the object was rapidly raised to 290°C. During this process, wet ammonia gas containing 25% moisture was continuously fed into the system. The air flow rate is 100L/min, and the material is always in a stirring state, keeping the temperature at 310°C, and keeping it warm for 40 minutes; continue to feed wet ammonia gas containing 10% water, the flow rate of wet ammonia gas is 20L/min, and maintain the temperature at 290°C. And keep it for 60 minutes, cool and discharge, and pulverize to get crystalline V-type ammonium polyphosphate.

Example 3

In a kneader made of ordinary 304 stainless steel, add 100kg of ammonium phosphate, 1.5kg of biuret, and 0.3kg of cyanuric acid at the same time. Wet ammonia gas containing 10% moisture is fed into the system, the flow rate of wet ammonia gas is 40L/min, and the temperature is rapidly raised to 320°C. During this process, wet ammonia gas containing 18% moisture is continuously fed, and the flow rate of wet ammonia gas is 120L /min, and keep the material in a state of agitation all the time, keep the temperature at 320°C, and keep it warm for 40 minutes; continue to feed wet ammonia gas containing 5% water, the flow rate of wet ammonia gas is 20L/min, maintain the temperature at 280°C, and keep it at 40 Minutes, cooling and discharging, crushing, and then crystal V-type ammonium polyphosphate can be obtained.

Example 4

In a kneader made of ordinary 304 stainless steel, add 100kg of diammonium hydrogen phosphate, and at the same time add 1.8kg of ammonium carbonate, 2kg of biuret, and 1.8kg of melamine as a mixed condensing agent. ℃ to melt the material, during which wet ammonia gas containing 25% water is fed into the system, the flow rate of wet ammonia gas is 40L/min, the system is rapidly heated to 320 ℃, and the wet ammonia gas containing 20% water is continuously fed in the process. Ammonia gas, wet ammonia gas flow rate 120L/min, and keep the material in a stirring state, keep the temperature at 320°C, and keep warm for 40 minutes; continue to feed wet ammonia gas containing 5% water, wet ammonia gas flow rate 20L/min, maintain The temperature is kept at 280°C for 60 minutes, cooled and discharged, and pulverized to obtain crystalline V-type ammonium polyphosphate.

Example 5

In a kneader made of ordinary 304 stainless steel, add 60kg of diammonium hydrogen phosphate, 40kg of ammonium dihydrogen phosphate, and at the same time add 9kg of urea, 3kg of methylurea and 18kg of melamine as a mixed condensation agent, heat to 180°C to melt the material, add The temperature of the condensing agent was 180°C. During this period, wet ammonia gas containing 5% moisture is introduced into the system, the flow rate of wet ammonia gas is 40L/min, and the temperature is rapidly raised to 320°C. During this process, wet ammonia gas containing 16% moisture is continuously fed into the system. The flow rate is 120L/min, and the material is always in a stirring state, keeping the temperature at 320°C, and keeping it warm for 40 minutes; continue to pass in wet ammonia gas containing 8% water, the flow rate of wet ammonia gas is 20L/min, maintain the temperature at 280°C, and Hold for 60 minutes, cool and discharge the material, and pulverize to obtain crystal V-type ammonium polyphosphate.

The five strong peaks of the ammonium polyphosphate XRD spectrum prepared by the present invention and the literature [C Y Shen. Preparation and characterization of crystalline long-chain ammonium polyphosphate, Journal of the American Chemical Society, 1969, 91 (1): 62-67.] proposed The comparison of d values of crystalline V-type ammonium polyphosphate is listed in the table below:

Comparison of the d values of five strong XRD peaks of crystalline V-type ammonium polyphosphate

d(nm) 1 2 3 4 5 Literature value 0.559 0.341 0.682 0.367 0.280 Invention value 0.560 0.342 0.685 0.367 0.281

As can be seen from the table, the ammonium polyphosphate prepared by the present invention is completely consistent with the literature value, indicating that the ammonium polyphosphate prepared by the present invention is crystal V type.

The above is only a preferred embodiment of the present invention, it should be pointed out that for those of ordinary skill in the art, without departing from the concept of the present invention, some improvements and modifications can also be made, and these improvements and modifications should also be considered Within the protection scope of the present invention.

Claims (6)

1. One pot method prepares the method for crystalline V-type ammonium polyphosphate, is characterized in that, concrete steps are: (1) In the kneader, add one, any two or three of ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate, add an amine-containing condensing agent, heat to 160-240°C, and pour into the system Introduce wet ammonia gas containing a certain amount of water, the flow rate of wet ammonia gas is 0.05-3.0L/min/kg, keep the temperature at 180-240°C, and keep warm for 5-60 minutes; (2) Rapidly raise the temperature to 250-320°C, continuously feed wet ammonia gas containing a certain amount of water during this process, keep the flow rate of wet ammonia gas at 0.05-3.0L/min/kg, and keep the material in a state of agitation all the time, Keep the temperature at 250-320°C and keep it warm for 20-60 minutes; (3) Continue to feed wet ammonia gas, the flow rate of wet ammonia gas is 0.05-3.0L/min/kg, maintain the temperature at 280-350°C, and keep it for 30-120 minutes, cool and discharge, crush, and you can get crystalline V-type polymer ammonium phosphate. 2. one pot method as claimed in claim 1 prepares the method for crystallization V type ammonium polyphosphate, it is characterized in that, in described step (1), kneader material is common 304 stainless steel or better 316L stainless steel . 3. one pot method as claimed in claim 1 prepares the method for crystalline V-type ammonium polyphosphate, it is characterized in that, in described step (1), containing amine condensation agent is urea, biuret, formazan One or a mixture of urea, guanyl urea, biuret, ammonium carbonate, cyanuric acid, and melamine. 4. the method for preparing crystalline V-type ammonium polyphosphate by one-pot method as claimed in claim 1, is characterized in that, in described step (1), the temperature that adds condensing agent is between room temperature to 280 ℃. 5. one pot method as claimed in claim 1 prepares the method for crystalline V-type ammonium polyphosphate, it is characterized in that, in described step (1), ammonium dihydrogen phosphate, diammonium hydrogen phosphate or ammonium phosphate weight The portion is 100kg, and the portion by weight of the amine-containing condensing agent is 0.5-50kg. 6. one pot method as claimed in claim 1 prepares the method for crystalline V-type ammonium polyphosphate, is characterized in that, in described step (1), wet ammonia is that ammonia gas feeds 0%-29% In the aqueous ammonia solution, the water vapor content in the wet ammonia gas is 0%-30%.

Images