Method for preparing stannous octoate at room temperature

Abstract

The method for preparing stannous octoate at room temperature comprises the following steps: putting isooctanoic acid, refined tin and a catalyst into a reaction container in proportion, slowly adding hydrogen peroxide to promote the reaction between isooctanoic acid and refined tin, and synthesizing stannous octoate in one step; then performing liquid-solid separation to obtain a stannous octoate intermediate; then washing the stannous octoate intermediate with water and performing reduced pressure distillation to obtain a stannous octoate product. The production process of the invention is short, the reaction process does not require heating, the utilization rate of hydrogen peroxide is high, and the production cost is low. Residual acid and washing water can be recycled, which is energy-saving and environmentally friendly. No other impurities are added during the reaction process, and the stannous octoate product produced by the reaction has high purity and good product quality.

Description

Technical Field

[0001] The invention relates to the technical field of hydrometallurgy and chemical engineering, and in particular to a method for preparing stannous octoate. Background Art

[0002] Stannous octoate is chemically known as stannous 2-ethylhexanoate, and is a chemical product of tin. Stannous octoate is easily hydrolyzed in both acidic and alkaline aqueous solutions, has a small pH range in which it can exist stably, and is easily oxidized and decomposed by oxygen in the air and other oxidants. Therefore, its preparation is difficult. Currently, the two methods that are more mature and have been put into large-scale production at home and abroad are saponification synthesis and electrolysis.

[0003] The saponification synthesis method is to first react isooctanoic acid with sodium hydroxide (or sodium carbonate) to obtain sodium octanoate, and then add stannous chloride solution to react with sodium octanoate to obtain stannous octanoate. The saponification synthesis method is easier to achieve large-scale production, has a wide adaptability to raw materials, and can use tin-containing materials with low impurity content as initial raw materials. However, this method uses stannous chloride as a raw material, and it is necessary to first prepare tin salts such as stannous chloride. The saponification process requires full neutralization of isooctanoic acid, and the alkali consumption is large. The stability of the synthesis process is poor, and the control of the feeding speed, the pH value of the system, and the composition of various raw materials are relatively strict. Improper control of conditions or changes in the composition of raw materials can easily cause unqualified products. At the same time, due to the use of a large amount of deionized water to wash the sodium chloride in stannous octanoate during the production process, a large amount of high-sodium salt wastewater that is difficult to treat is generated, and the pressure of wastewater treatment is high.

[0004] The electrolysis method uses metallic tin as the anode plate and a stainless steel bar as the cathode, which are placed in a circular electrolytic cell. Sodium chloride is used as the electrolyte. Isooctanoic acid and additives are added to the electrolyte. The pH is controlled to be around 4 for electrolysis. The tin anode dissolves and reacts with the hydroxide and isooctanoic acid produced at the cathode to form stannous octanoate. Stannous octanoate has a large density and sinks to the bottom of the electrolytic cell. After being taken out, it is filtered to remove solid impurities and dehydrated by vacuum distillation to obtain the stannous octanoate product. The electrolyte can be reused. The electrolysis method uses metallic tin and isooctanoic acid as raw materials to synthesize stannous octanoate in one step. There is no need to prepare stannous chloride. During the electrolysis process, a large amount of hydrogen is released at the cathode, and the alkali consumption for neutralizing isooctanoic acid is small. Compared with the saponification method, the electrolysis process and product have good stability. However, sponge tin is easily precipitated at the cathode, the DC power consumption is high, metallic tin is required as a raw material, and the control requirements for the electrolyte temperature and pH value are relatively strict. The problem is that a small amount of sponge tin is precipitated at the cathode during the electrolysis process, resulting in a low direct tin recovery rate (about 89%). After a period of electrolysis, the electrolyte temperature is too high and the DC power consumption is high. At the same time, due to the need to control the rapid mixing process of divalent tin and isooctanoic acid, the electrolysis process is difficult to achieve large-scale automation, resulting in a relatively high total production cost.

[0005] Other reported methods for preparing stannous octoate include: (1) Stannous oxide method: stannous oxide and isooctanoic acid are mixed, synthesized at a temperature above 150°C, and distilled and dehydrated. The solid impurities are filtered out to obtain the stannous octoate product. This method has high product purity and simple process, but requires expensive stannous oxide as raw material; (2) Methanol method: Anhydrous stannous chloride is first reacted with triethylamine and methanol to obtain dimethoxy stannous acid, which is then reacted with isooctanoic acid at 70-80°C to obtain stannous octoate. This method is a non-aqueous solution synthesis with high product purity, but there are problems with the regeneration of triethylamine and the recycling of methanol, as well as the preparation of anhydrous stannous chloride. The cost is high and it is difficult to apply on a large scale. (3) Pressurization method: Tin, isooctanoic acid and water are mixed in a closed container under high temperature and pressure to synthesize stannous octoate. After liquid-solid separation, the mixture is allowed to stand and the layers are separated. The lower layer is distilled and dehydrated to obtain the stannous octoate product. This method has a short production process and low production cost, but a large amount of hydrogen is generated during the high-temperature and high-pressure reaction, which poses certain safety risks. Currently, there is no report on the industrialization of this method. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the prior art and provide a method for producing stannous octoate which has the advantages of short production process, low production cost, energy saving and environmental protection, and can ensure the purity of the final product and good product quality.

[0007] The purpose of the present invention is achieved through the following technical solutions:

[0008] The method for preparing stannous octoate at room temperature comprises the following steps: putting isooctanoic acid, refined tin and a catalyst into a reaction container in proportion, slowly adding hydrogen peroxide to promote the reaction between isooctanoic acid and refined tin, and synthesizing stannous octoate in one step; then performing liquid-solid separation, standing and stratifying by using specific gravity difference, wherein the upper layer is isooctanoic acid returned to the synthesis reaction, and the lower layer is a stannous octoate intermediate; the liquid-solid mass ratio of isooctanoic acid to refined tin is 3-10:1, and the amount of hydrogen peroxide used is 1-4 times of the theoretical amount; then washing the stannous octoate intermediate with water, standing and stratifying, the upper layer is water returned to the washing process, and the lower layer is stannous octoate, and the stannous octoate is subjected to reduced pressure distillation to obtain a stannous octoate product.

[0009] Furthermore, the catalyst is a water-soluble ammonium salt, and the amount of the catalyst used is 1% to 5% of the amount of refined tin.

[0010] Furthermore, the water-soluble ammonium salt is one or both of ammonium nitrite and ammonium bicarbonate.

[0011] Furthermore, the purity of the hydrogen peroxide is 30-38%.

[0012] Furthermore, the distillation solution obtained by the reduced-pressure distillation of stannous octoate is returned to the washing step.

[0013] Furthermore, the refined tin is tin powder or tin flowers with a particle size of 2 to 5 mm.

[0014] Compared with the prior art, the present invention has at least the following advantages:

[0015] (1) Whether it is the electrolysis method or the saponification method, Cl- is involved. The present invention effectively avoids inorganic anions such as Cl- and ensures the purity of the final product;

[0016] (2) The raw material of the saponification method is a chemical product synthesized from refined tin. The present invention reduces the cost of synthesizing other chemical products, and the production cost is significantly reduced;

[0017] (3) The raw material of the present invention is refined tin, which brings in less impurities. The residual acid in the reaction process can be returned to the synthesis process, and the water in the washing process is returned to the washing process, which brings in less impurities and produces a good product quality.

[0018] (4) The oxidation synthesis of stannous octoate in the present invention has a short process and a relatively simple preparation method, and does not require a complicated preparation process. The synthesis is carried out at room temperature and pressure, and the process is flexible, and large-scale controllable production is easy to achieve.

[0019] In summary, the production process of the present invention is short, the reaction process does not require heating, the utilization rate of hydrogen peroxide is high, and the production cost is low. Residual acid and washing water can be recycled, which is energy-saving and environmentally friendly. No other impurities are added during the reaction process, and the stannous octoate product produced by the reaction has high purity and good product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0021] The method for preparing stannous octoate at room temperature, such as Figure 1 As shown, the steps are as follows:

[0022] (1) Put isooctanoic acid, refined tin and catalyst into a reactor in proportion, slowly add hydrogen peroxide to promote the reaction between isooctanoic acid and refined tin, and synthesize stannous octoate in one step. The liquid-solid mass ratio of isooctanoic acid to refined tin is 3-10:1, and the amount of hydrogen peroxide is 1-4 times the theoretical amount. The refined tin is tin powder or tin flower with a particle size of 2-5 mm. The added catalyst is a water-soluble ammonium salt such as ammonium nitrite and ammonium bicarbonate, and the amount of the catalyst is 1%-5% of the amount of refined tin. The purity of hydrogen peroxide is 30-38%. The reaction formula is as follows:

[0023] Sn+2C7H 15 COOH + H2O2 = Sn(C7H 15 COO)2+2H2O.

[0024] (2) Liquid-solid separation is carried out by static stratification using the difference in specific gravity. The upper layer is the residual acid (isooctanoic acid), which is returned to the synthesis reaction, and the lower layer is the stannous octoate intermediate.

[0025] (3) The intermediate stannous octoate is washed with water, and after standing for stratification, the upper layer is water and returned to the washing process, and the lower layer is stannous octoate, and the stannous octoate is distilled under reduced pressure to obtain the stannous octoate product. The distilled solution from the reduced pressure distillation can be returned to the washing process multiple times.

[0026] (4) Pack the stannous octoate products and store them in warehouse.

[0027] Example 1

[0028] The method for preparing stannous octoate at room temperature is as follows: in a 3L reactor, 1.5kg of isooctanoic acid and 25g of ammonium nitrite are added, stirring is turned on and 0.5kg of tin flowers are added. 300ml of hydrogen peroxide with a purity of 35% is slowly dripped, and the dripping is completed within 2 hours. The overall reaction time is 8 hours. After the reaction is completed, the upper layer is isooctanoic acid that is not completely reacted, and the lower layer is the intermediate stannous octoate. Liquid-solid separation is performed to separate the intermediate stannous octoate. The intermediate stannous octoate is washed with water, left to stand and cleared, the supernatant is drawn off, and the washed stannous octoate is added to a distillation kettle to distill and remove moisture to obtain 1689g of stannous octoate product, which meets the following quality standards.

[0029] Qualified stannous octoate products can be sold after being measured and packaged.

[0030] Example 2

[0031] The method for preparing stannous octoate at room temperature is as follows: in a 3L reactor, 2kg of isooctanoic acid and 2g of ammonium bicarbonate are added, stirring is turned on and 0.2kg of tin flowers are added. 50ml of hydrogen peroxide with a purity of 30% is slowly added dropwise, and the addition is completed within 1 hour. The overall reaction time is 5 hours. After the reaction is completed, the stratification is allowed to stand, and the upper layer is the isooctanoic acid that is not completely reacted, and the lower layer is the intermediate stannous octoate. Liquid-solid separation is performed to separate the intermediate stannous octoate. The intermediate stannous octoate is washed with water, allowed to stand and settle, and the supernatant is drawn off. The washed stannous octoate is added to a distillation kettle and distilled to remove moisture to obtain 682g of stannous octoate product, and the product meets the following quality standards.

[0032]

[0033] Qualified stannous octoate products can be sold after being measured and packaged.

[0034] Example 3

[0035] The method for preparing stannous octoate at room temperature is as follows: in a 3L reactor, 1.8kg isooctanoic acid, 7g ammonium nitrite and 2g ammonium bicarbonate are added, stirring is turned on and 300g tin flowers are added. 150ml of hydrogen peroxide with a purity of 38% is slowly dripped, and the dripping is completed within 2 hours. The overall reaction time is 6 hours. After the reaction is completed, the stratification is allowed to stand, and the upper layer is the isooctanoic acid that is not completely reacted, and the lower layer is the intermediate stannous octoate. Liquid-solid separation obtains the intermediate stannous octoate. Add water to wash the intermediate stannous octoate, let it stand and settle, and the supernatant is drawn away. The washed stannous octoate is added to a distillation kettle to distill and remove moisture to obtain 1028g of stannous octoate product, and the product meets the following quality standards.

[0036]

[0037] Qualified stannous octoate products can be sold after being measured and packaged.

[0038] Unless otherwise specified, all percentages described in the present invention are by mass percentages.

Claims

1. A method for preparing stannous octoate at room temperature, characterized in that: Put isooctanoic acid, refined tin and a catalyst into a reaction container in proportion, slowly add hydrogen peroxide to promote the reaction between isooctanoic acid and refined tin, and synthesize stannous octoate in one step; then carry out liquid-solid separation, stand and separate by gravity difference, the upper layer is isooctanoic acid returned to the synthesis reaction, and the lower layer is the stannous octoate intermediate; the liquid-solid mass ratio of isooctanoic acid to refined tin is 3-10:1, and the amount of hydrogen peroxide used is 1-4 times of the theoretical amount; then wash the stannous octoate intermediate with water, stand and separate, the upper layer is water returned to the washing process, and the lower layer is stannous octoate, and the stannous octoate is distilled under reduced pressure to obtain a stannous octoate product; the catalyst is one or both of ammonium nitrite and ammonium carbonate.

2. The method for preparing stannous octoate at room temperature according to claim 1, wherein The amount of catalyst used is 1%~5% of the refined tin amount.

3. The method for preparing stannous octoate at room temperature according to claim 1 or 2, characterized in that, The purity of the hydrogen peroxide is 30-38%.

4. The method for preparing stannous octoate at room temperature according to claim 1 or 2, characterized in that, The distillate solution obtained by distilling stannous octoate under reduced pressure is returned to the washing step.

5. The method for preparing stannous octoate at room temperature according to claim 1 or 2, characterized in that, The refined tin is tin powder or tin flower with a particle size of 2-5 mm.

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