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Preparation method of potassium dihydrogen phosphate

A technology of potassium dihydrogen phosphate and potassium hydroxide, which is applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., and can solve problems such as increased cost, impact on yield, and high operational risk

Inactive Publication Date: 2014-06-04
TIANJIN KERMEL CHEM REAGENT
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] Potassium hydroxide is a strong alkaline substance, which is strongly corrosive to various filter materials. It is highly risky to filter it directly, and after it is prepared into a solution with phosphoric acid, due to the high solubility of potassium dihydrogen phosphate, it needs Concentrate to a certain concentration and then crystallize to obtain a satisfactory yield, which increases energy consumption
[0014] However, directly reacting solid potassium hydroxide with phosphoric acid is too violent and dangerous due to the reaction of strong acid and strong base at high concentration. At the same time, a large amount of product is precipitated, and mechanical impurities cannot be effectively removed. For example, the product is filtered and crystallized after adding pure water. , it will inevitably increase the amount of mother liquor, which not only affects the yield, but also increases the production process, resulting in increased costs

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0039] Inject 600ml of pure water into a 5000ml beaker, stir and dissolve 1100g of solid potassium hydroxide; pour the potassium hydroxide solution into a 3000ml three-necked flask, start stirring; pour 1250g of phosphoric acid 85% by mass into a separatory funnel, and Connect with the three-necked flask, open the cut-off gate at the bottom of the separatory funnel after completion, and add phosphoric acid at a rate of 20g / min; after stirring for about 10 minutes, pour 850g of phosphoric acid with a mass percentage of 85% into the separatory funnel, open the cut-off gate to let the phosphoric acid Add at a speed of 15g / min; stir for 10 minutes, and fine-tune the pH value with dipotassium hydrogen phosphate mother liquor to make the pH=4.0; stir and cool to 50°C, take out the precipitated crystals, and filter them in a Buchner funnel; The final crystallization is poured into a centrifuge for solid-liquid separation. If there is no flow of mother liquor at the outlet of the mothe...

Embodiment 2

[0041] Inject 800ml of pure water into a 5000ml beaker, stir and dissolve 1100g of potassium hydroxide; pour the potassium hydroxide solution into a 3000ml three-neck flask, start stirring; pour 1250g of phosphoric acid 85% by mass into a separatory funnel, and mix with The three-necked flasks are connected. After completion, open the cut-off gate at the bottom of the separating funnel to add phosphoric acid at a rate of 20g / min; Add at a speed of 15g / min; stir for 10 minutes, fine-tune the pH value with dipotassium hydrogen phosphate mother liquor to make the pH=4.0; stir and cool to 50°C, take out the precipitated crystals, and filter them in a Buchner funnel; The final crystallization is poured into a centrifuge for solid-liquid separation. If there is no flow of mother liquor at the outlet of the mother liquor in the centrifuge, the separation is considered complete; the solid crystal is poured into a desiccator and dried at 80°C to obtain dihydrogen phosphate potassium. ...

Embodiment 3

[0043]Pump 300kg of pure water into a 1000L enamel kettle by a vacuum pump, start the agitator; put 425kg of solid potassium hydroxide into the enamel kettle at a speed of 4.25kg / min; stir for 10 minutes to completely dissolve the solid potassium hydroxide to form Homogeneous potassium hydroxide solution; along with stirring, open the phosphoric acid head tank cut-off door, join 455kg mass percent of 85% phosphoric acid in the solution of potassium hydroxide with the speed of kg / min; Stir for 20 minutes, make it fully Complete reaction, forms the dipotassium hydrogen phosphate solution of uniform clarification; Open the discharge valve valve at the bottom of the kettle, the clarified solution of potassium hydrogen phosphate flows into filter and filters; When the dipotassium hydrogen phosphate solution of filtration is pumped to After the enamel kettle, start stirring; along with stirring, open the phosphoric acid head tank cut-off door, add 350 kg of phosphoric acid with a mas...

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PUM

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Abstract

The invention discloses a preparation method of potassium dihydrogen phosphate. According to the preparation method, two-step reaction is adopted. The preparation method comprises following steps: phosphoric acid is reacted with potassium hydroxide so as to obtain dipotassium phosphate with extremely high solubility firstly, and a solution which can be filtered and possesses a pH value close to 7 is prepared with a small amount of water; and an obtained filtrate is neutralized using a phosphoric acid solution so as to obtain pure potassium dihydrogen phosphate. The preparation method is capable of removing insoluble substances and mechanical impurities in raw materials; no special filtration is needed; reaction conditions are mild; equipment is simple; mother liquor amount is less; condensation is avoided; energy consumption and labor intensity are reduced; yield is increased; and cost is reduced greatly.

Description

technical field [0001] The invention relates to the field of chemical synthesis, in particular to a preparation method of potassium dihydrogen phosphate. Background technique [0002] Potassium dihydrogen phosphate (KH 2 PO 4 ), colorless tetragonal crystal or white crystalline powder, relative density 2.338, melting point 252.6°C, easily soluble in water, at 100°C, solubility is 83.5g / 100ml water, aqueous solution is acidic, mass percentage is 1% potassium dihydrogen phosphate The pH value of the solution is 4.0, insoluble in alcohol, deliquescent, it melts into a transparent liquid when heated to 400°C, and solidifies into opaque glassy potassium metaphosphate after cooling. [0003] There are many production methods of potassium dihydrogen phosphate, which are roughly summarized as neutralization method, extraction method, ion exchange method, double decomposition method, direct method, crystallization method and electrolysis method. [0004] The neutralization method ...

Claims

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Application Information

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IPC IPC(8): C01B25/30
Inventor 苏学松陈曙李刚林立成秦汉超
Owner TIANJIN KERMEL CHEM REAGENT
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