Deacidification adsorbent for phosphate fire-resistant oil as well as preparation method and application of deacidification adsorbent

Abstract

The invention belongs to the technical field of phosphate fire-resistant oil adsorption treatment, and relates to a deacidification adsorbent for phosphate fire-resistant oil as well as a preparation method and application of the deacidification adsorbent. The catalyst comprises the following components in percentage by mass: 50-80% of activated aluminum oxide, 10-30% of molecular sieve, 5-15% of metal oxide and 2-10% of binder. The adsorbent disclosed by the invention has high adsorption capacity, high selectivity, strong chemical neutralization capability and good physical stability, and an efficient, deep and stable deacidification effect on the phosphate fire-resistant oil is realized.

Description

Technical Field

[0001] This invention belongs to the field of phosphate ester fire-resistant oil adsorption treatment technology, and relates to a deacidification adsorbent for phosphate ester fire-resistant oil, its preparation method and application. Background Technology

[0002] Phosphate ester fire-resistant oils, due to their excellent fire resistance, high thermal conductivity, and good thermal oxidation stability, have become a widely used high-pressure fire-resistant hydraulic medium in large generator sets, especially in steam turbine speed control systems. This type of oil can maintain stable system operation under harsh conditions of high temperature and high pressure, effectively improving the safety and reliability of the equipment.

[0003] However, in actual operation, phosphate ester fire-resistant oil is subject to chemical degradation and hydrolysis reactions due to temperature, moisture, dissolved oxygen, and the catalytic effects of metals (such as iron and copper), generating low-molecular-weight acidic phosphate esters, phenolic compounds, and other organic acids. These acidic products not only catalyze further aging of the oil, creating a vicious cycle, but also corrode metal components in the hydraulic system, accelerate the aging of sealing materials, and promote the formation of sludge and deposits. The resulting oil contamination, component wear, and control system malfunctions seriously threaten the safe and stable operation of the unit and increase maintenance costs.

[0004] To maintain oil performance and extend its service life, it is essential to effectively remove acidic substances generated during use. Currently, industrial regeneration of acidic phosphate ester fire-resistant oils mainly relies on adsorption methods, with commonly used adsorbents including activated clay, diatomaceous earth, and activated alumina. Activated clay has a certain adsorption and deacidification capacity, but its adsorption capacity is limited, its selectivity for acidic substances is not high, and it may release impurity ions such as aluminum and silicon during adsorption, causing secondary pollution of the oil. In addition, the disposal of waste activated clay after use is difficult and poses environmental hazards. Although activated alumina possesses relatively good thermal stability and mechanical strength, when used alone, its adsorption rate and deacidification effect on specific acidic components in phosphate ester oils are still insufficient, making it difficult to meet the regeneration requirements of high efficiency and long-term operation. Summary of the Invention

[0005] To address the technical problems of existing adsorbents (such as activated clay and alumina) such as low adsorption capacity, incomplete deacidification, potential introduction of impurities, and difficulty in waste disposal, this invention provides a deacidification adsorbent for phosphate ester fire-resistant oil, its preparation method, and its application. The adsorbent of this invention has high adsorption capacity, high selectivity, strong chemical neutralization ability, and good physical stability, achieving efficient, deep, and stable deacidification of phosphate ester fire-resistant oil.

[0006] To achieve the above objectives, the present invention employs the following technical solution: In a first aspect, the present invention provides an acid removal adsorbent for phosphate ester fire-resistant oil, comprising, by mass percentage, 50% to 80% activated alumina, 10% to 30% molecular sieve, 5% to 15% metal oxide and 2% to 10% binder.

[0007] Preferably, the molecular sieve is a NaY type molecular sieve or a 13X type molecular sieve.

[0008] Preferably, the metal oxide is calcium oxide, magnesium oxide, or zinc oxide.

[0009] Preferably, the adhesive is silica sol or aluminum sol.

[0010] Preferably, the specific surface area of ​​the activated alumina is 200~400 m². 2 / g, with a pore volume of 0.3~0.6mL / g.

[0011] Preferably, the particle size of the molecular sieve is 100-300 mesh.

[0012] Preferably, the particle size of the metal oxide is 200-400 mesh.

[0013] Secondly, the present invention provides a method for preparing an acid-removing adsorbent for phosphate ester fire-resistant oil, comprising the following steps: Activated alumina, molecular sieves, and metal oxides are mixed to obtain a mixture; A binder is added to the mixture, kneaded until uniform, and then shaped to obtain an adsorbent precursor. The adsorbent precursor is dried and calcined to obtain the deacidification adsorbent.

[0014] Preferably, the drying conditions are: drying at 100~120℃ for 2~4 hours; the calcination conditions are: calcination at 400~600℃ for 3~5 hours.

[0015] Thirdly, the present invention provides an application of a deacidifying adsorbent in the deacidification treatment of phosphate ester fire-resistant oil, wherein the deacidification treatment conditions are as follows: the amount of the deacidifying adsorbent added is 1% to 5% of the weight of the phosphate ester fire-resistant oil, the treatment temperature is 40 to 60°C, and the treatment time is 2 to 4 hours.

[0016] Compared with the prior art, the present invention has the following beneficial effects: Activated alumina forms the main framework of the adsorbent, providing a large specific surface area and physical adsorption capacity, ensuring a basic deacidification effect. Molecular sieves, utilizing their regular pore structure and surface characteristics, achieve selective adsorption and deep purification of specific acidic small molecules, compensating for the shortcomings of alumina's wide pore size distribution. Metal oxides, through irreversible chemical neutralization reactions with acidic substances, significantly enhance the adsorbent's acid load capacity and the thorough removal of acidic substances. The binder, while ensuring a firm bond between the components and forming a molded body with sufficient mechanical strength, avoids excessive clogging of effective pores, ensuring the mass transfer efficiency of acidic substances within the adsorbent. The adsorbent of this invention combines high adsorption capacity, high selectivity, strong chemical neutralization ability, and good physical stability, achieving a highly efficient, deep, and stable deacidification effect on phosphate ester fire-resistant oils. Detailed Implementation

[0017] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0018] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0019] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0020] In this article, unless otherwise specified, the terms “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of”. For example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a”.

[0021] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0022] The first objective of this invention is to provide an acid removal adsorbent for phosphate ester fire-resistant oil, comprising, by mass percentage, 50% to 80% activated alumina, 10% to 30% molecular sieve, 5% to 15% metal oxide, and 2% to 10% binder.

[0023] Activated alumina, serving as the main framework, relies primarily on its large specific surface area and abundant pore structure to physically adsorb acidic substances, forming the foundation for deacidification. Molecular sieves, utilizing their regular crystalline pore structure, achieve selective adsorption and sieving of acidic small molecules of specific sizes and polarities, enhancing the selectivity and depth of deacidification. The core function of metal oxides lies in chemical neutralization; their alkaline surfaces can undergo irreversible chemical reactions with acidic substances to generate stable salts, thereby thoroughly removing acidic components and breaking the autocatalytic cycle of oil aging. The key function of the binder is to integrate the above active components into a stable whole with sufficient mechanical strength through molding and curing, ensuring structural durability while maintaining a pore structure conducive to mass transfer. The adsorbent of this invention possesses high adsorption capacity, high selectivity, strong chemical neutralization ability, and good physical stability, achieving efficient, deep, and stable deacidification of phosphate ester fire-resistant oils.

[0024] The molecular sieve is either a NaY-type molecular sieve or a 13X-type molecular sieve. NaY-type molecular sieves have a large pore diameter and a three-dimensional cross-channel system, while 13X-type molecular sieves possess even larger pore sizes and strong ion exchange capabilities. Both types of molecular sieves can effectively accommodate and selectively adsorb small-molecule organic acids and polar acidic substances produced by the degradation of phosphate ester fire-resistant oils. Their regular channels act like "molecular sieves," achieving size- and polarity-based sieving and adsorption of target acidic components. Simultaneously, the abundant sodium ions on their surfaces can exchange with other cations (such as hydrogen ions), thereby further enhancing the fixation and removal of acidic substances through chemical action. This synergy between physical sieving and chemical adsorption significantly improves the selective adsorption capacity and deep purification efficiency of the composite adsorbent for specific acidic impurities in complex oils, avoiding the shortcomings of poor selectivity and incomplete deacidification found in ordinary adsorbents.

[0025] The metal oxides mentioned are calcium oxide, magnesium oxide, or zinc oxide, all of which are alkaline metal oxides capable of powerful and irreversible chemical neutralization of acidic substances. Specifically, these metal oxides can chemically react with various organic acids (such as acidic phosphate esters) produced by the degradation of phosphate ester fire-resistant oil to generate corresponding metal salts and water. This process not only rapidly and thoroughly consumes the acidic components in the oil, significantly reducing the acid value, but also ensures that the reaction products remain stably within the pores of the adsorbent and are not released back into the oil, thus achieving deep chemical purification. Compared to simple physical adsorption, this chemical neutralization mechanism greatly enhances the acid capacity and deacidification thoroughness of the adsorbent, effectively breaking the autocatalytic degradation cycle caused by the increase in the acid value of the oil, which is crucial for maintaining the long-term stability of the oil and extending its service life.

[0026] The binder is either silica sol or alumina sol. These two sols are themselves nanoscale active colloidal particles. After calcination, they form a robust inorganic network framework that firmly binds active components such as activated alumina, molecular sieves, and metal oxides together. This endows the adsorbent with good mechanical strength and wear resistance, preventing it from pulverizing during stirring and use. More importantly, unlike traditional binders that may clog pores, silica sol or alumina sol forms a porous structure after curing. This not only does not significantly sacrifice the total specific surface area and pore volume of the adsorbent, but also helps to construct more developed and stable interconnected channels, ensuring efficient diffusion and mass transfer of acidic substances within the adsorbent and achieving an ideal balance between strength and adsorption performance.

[0027] The specific surface area of ​​the activated alumina is 200~400m². 2 The specific physical properties of activated alumina ensure that it provides an extremely high specific surface area, creating sufficient reaction sites for the physical adsorption of acidic substances, thus laying the foundation for high-efficiency deacidification capacity. At the same time, it possesses a sufficiently large and suitable pore space, which not only facilitates the smooth diffusion of larger acid molecules in the oil to the internal active sites, improving the adsorption rate, but also provides a good dispersion environment for the loaded molecular sieves and metal oxide particles, avoiding pore blockage and ensuring the effective synergistic effect of each component. Ultimately, it achieves an ideal balance between the overall adsorption capacity and mass transfer efficiency of the adsorbent.

[0028] The molecular sieve has a particle size of 100-300 mesh. This particle size range ensures that the molecular sieve particles have sufficient specific surface area to fully expose their regular pore structure and active sites, thereby achieving efficient and selective adsorption of small molecule acidic substances. At the same time, it can achieve good particle size distribution and uniform dispersion with other components such as activated alumina and metal oxides during the mixing and molding process, avoiding stratification or aggregation caused by excessive particle size differences. This ensures that the synergistic effect of each active component is fully exerted in the final adsorbent product and is conducive to the formation of a stable and unobstructed macroscopic pore structure, thus optimizing mass transfer efficiency.

[0029] The metal oxide particles have a size of 200-400 mesh. This particle size range ensures that the metal oxide particles have an extremely high specific surface area, allowing their basic active sites to fully and rapidly contact and undergo irreversible chemical reactions with acidic substances in the oil, thereby achieving deep and rapid deacidification. Simultaneously, the fine particle size facilitates uniform dispersion within the activated alumina-based matrix, avoiding the waste of active sites and increased mass transfer resistance caused by localized agglomeration. This ensures that the chemical neutralization capacity is efficiently and consistently utilized throughout the adsorbent, perfectly complementing its physical and selective adsorption functions.

[0030] A second objective of this invention is to provide a method for preparing a deacidifying adsorbent for phosphate ester fire-resistant oil, comprising the following steps: Activated alumina, molecular sieves, and metal oxides are mixed to obtain a mixture; A binder is added to the mixture, kneaded until uniform, and then shaped to obtain an adsorbent precursor. The adsorbent precursor is dried at 100-120°C for 2-4 hours and calcined at 400-600°C for 3-5 hours to obtain the deacidification adsorbent.

[0031] This invention achieves uniform dispersion of activated alumina, molecular sieves, and metal oxides through dry mixing; subsequently, a binder is introduced for thorough kneading, forming a uniformly encapsulated plastic body between particles, thus constructing a stable microstructure. The drying process effectively removes free moisture from the molded body, avoiding structural damage caused by rapid dehydration; the subsequent high-temperature calcination process promotes the gelation transformation of the binder, forming a robust skeletal structure, while simultaneously activating the surface properties of the material and optimizing pore characteristics. Ultimately, a stable product with ideal mechanical strength, well-developed pore structure, and excellent adsorption activity is obtained, ensuring its sustained purification performance under complex working conditions.

[0032] The third objective of this invention is to provide an application of a deacidifying adsorbent in the deacidification treatment of phosphate ester fire-resistant oil. The deacidification treatment conditions are as follows: the amount of deacidifying adsorbent added is 1% to 5% of the weight of the phosphate ester fire-resistant oil. This dosage range ensures sufficient acid capacity and purification effect while also considering economic efficiency. The treatment temperature is controlled between 40 and 60°C. This mild temperature condition significantly reduces oil viscosity, promotes mass transfer and diffusion of acidic substances to the active sites of the adsorbent, and avoids accelerated oil oxidation or adsorbent performance degradation caused by excessively high temperatures. The treatment time is set to 2 to 4 hours, which is sufficient to ensure that the adsorption-neutralization reaction reaches equilibrium, achieving the goal of deep deacidification. Through the above synergistically optimized process conditions, the adsorbent of this invention can achieve efficient and stable removal of acidic substances from phosphate ester fire-resistant oil under mild operating conditions, providing a reliable and practical technical solution for oil maintenance and regeneration in industrial settings.

[0033] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0034] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0035] Example 1 Weigh out 500g of activated alumina powder, 250g of NaY molecular sieve powder (100 mesh), 150g of calcium oxide powder (200 mesh), and 100g of aluminum sol.

[0036] The weighed activated alumina powder, NaY molecular sieve powder, and calcium oxide powder are added together into a double cone mixer. The mixer is started and stirred until all components are fully mixed and homogeneous to obtain a mixture.

[0037] Transfer the well-mixed mixture to a twin-shaft mixer. While mixing, use a sprayer to slowly and evenly spray aluminum sol into the mixed powder, and continue kneading until the material forms a uniformly moist and well-plasticized adsorbent precursor.

[0038] The adsorbent precursor was dried at 100℃ for 4 hours to completely remove free moisture. The dried precursor was then transferred to a temperature-controlled muffle furnace and heated to 400℃ at a rate of 5℃ / min under air atmosphere. The furnace was then held at this temperature for 5 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain the deacidifying adsorbent.

[0039] Example 2 Weigh out 800g of activated alumina powder, 100g of NaY molecular sieve powder (150 mesh), 50g of calcium oxide powder (250 mesh), and 50g of aluminum sol.

[0040] The weighed activated alumina powder, NaY molecular sieve powder, and calcium oxide powder are added together into a double cone mixer. The mixer is started and stirred until all components are fully mixed and homogeneous to obtain a mixture.

[0041] Transfer the well-mixed mixture to a twin-shaft mixer. While mixing, use a sprayer to slowly and evenly spray aluminum sol into the mixed powder, and continue kneading until the material forms a uniformly moist and well-plasticized adsorbent precursor.

[0042] The adsorbent precursor was dried at 120℃ for 4 hours to completely remove free moisture. The dried precursor was then transferred to a temperature-controlled muffle furnace and heated to 400℃ at a rate of 5℃ / min under air atmosphere. The furnace was then held at this temperature for 5 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain the deacidifying adsorbent.

[0043] Example 3 Weigh out 600g of activated alumina powder, 300g of NaY molecular sieve powder (particle size 200 mesh), 50g of magnesium oxide powder (particle size 300 mesh), and 50g of silica sol.

[0044] The weighed activated alumina powder, NaY molecular sieve powder, and magnesium oxide powder are added together into a double cone mixer. The mixer is started and stirred until all components are fully mixed and homogeneous to obtain a mixture.

[0045] Transfer the well-mixed mixture to a twin-shaft mixer. While mixing, use a sprayer to slowly and evenly spray the silica sol into the mixed powder, and continue kneading until the material forms an adsorbent precursor with uniform moisture and good plasticity.

[0046] The adsorbent precursor was dried at 110℃ for 3 hours to completely remove free moisture. The dried precursor was then transferred to a temperature-controlled muffle furnace and heated to 500℃ at a rate of 8℃ / min under air atmosphere, and calcined at this temperature for 4 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain the deacidifying adsorbent.

[0047] Example 4 Weigh out 750g of activated alumina powder, 150g of 13X type molecular sieve powder (particle size 250 mesh), 150g of zinc oxide powder (particle size 350 mesh), and 20g of silica sol.

[0048] The weighed activated alumina powder, 13X molecular sieve powder, and zinc oxide were added together into a double cone mixer. The mixer was started and stirred until all components were fully mixed and homogeneous to obtain a mixture.

[0049] Transfer the well-mixed mixture to a twin-shaft mixer. While mixing, use a sprayer to slowly and evenly spray the silica sol into the mixed powder, and continue kneading until the material forms an adsorbent precursor with uniform moisture and good plasticity.

[0050] The adsorbent precursor was dried at 120℃ for 2 hours to completely remove free moisture. The dried precursor was then transferred to a temperature-controlled muffle furnace and heated to 600℃ at a rate of 10℃ / min under air atmosphere. The furnace was then held at this temperature for 3 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain the deacidifying adsorbent.

[0051] Example 5 Weigh out 700g of activated alumina powder, 200g of 13X type molecular sieve powder (300 mesh), 80g of zinc oxide powder (400 mesh), and 100g of silica sol.

[0052] The weighed activated alumina powder, 13X molecular sieve powder, and zinc oxide powder are added together into a double cone mixer. The mixer is started and stirred until all components are fully mixed and homogeneous to obtain a mixture.

[0053] Transfer the well-mixed mixture to a twin-shaft mixer. While mixing, use a sprayer to slowly and evenly spray the silica sol into the mixed powder, and continue kneading until the material forms an adsorbent precursor with uniform moisture and good plasticity.

[0054] The adsorbent precursor was dried at 120℃ for 2 hours to completely remove free moisture. The dried precursor was then transferred to a temperature-controlled muffle furnace and heated to 600℃ at a rate of 10℃ / min under air atmosphere. The furnace was then held at this temperature for 3 hours. After calcination, the furnace was allowed to cool naturally to room temperature to obtain the deacidifying adsorbent.

[0055] Performance testing: One kilogram of phosphate ester fire-resistant oil sample from a power plant, which had been in service for many years and had an acid value that had increased to 0.48 mg KOH / g, was placed in a stoppered conical flask. 30 grams of the deacidifying adsorbent prepared in Example 1 were weighed and added to the oil sample. The conical flask was placed in a constant-temperature water bath shaker, the treatment temperature was set to 50°C, and the sample was shaken at a frequency of 150 times / minute for 3 hours. The acid value of the oil sample before and after the adsorption treatment was measured (according to the GB / T264 standard method). The results showed that after treatment with the adsorbent prepared in Example 1, the acid value of the oil sample decreased from 0.48 mg KOH / g to 0.09 mg KOH / g, with an acid value reduction rate of 81.3%. The deacidifying adsorbent prepared in this invention can achieve efficient and deep deacidification and purification of deteriorated phosphate ester fire-resistant oil, with significant effects and effectively restoring the acid index of the oil.

[0056] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A deacidifying adsorbent for phosphate ester fire-resistant oil, characterized in that, It comprises, by weight percentage, 50%–80% activated alumina, 10%–30% molecular sieve, 5%–15% metal oxides, and 2%–10% binder.

2. The deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 1, characterized in that, The molecular sieve is a NaY type molecular sieve or a 13X type molecular sieve.

3. The deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 1, characterized in that, The metal oxide is calcium oxide, magnesium oxide, or zinc oxide.

4. The deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 1, characterized in that, The binder is silica sol or aluminum sol.

5. The deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 1, characterized in that, The specific surface area of ​​the activated alumina is 200~400m². 2 / g, with a pore volume of 0.3~0.6mL / g.

6. The deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 1, characterized in that, The molecular sieve has a particle size of 100-300 mesh.

7. The deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 1, characterized in that, The particle size of the metal oxide is 200-400 mesh.

8. A method for preparing a deacidifying adsorbent for phosphate ester fire-resistant oil according to any one of claims 1 to 7, characterized in that, Includes the following steps: Activated alumina, molecular sieves, and metal oxides are mixed to obtain a mixture; A binder is added to the mixture, kneaded until uniform, and then shaped to obtain an adsorbent precursor. The adsorbent precursor is dried and calcined to obtain the deacidification adsorbent.

9. A method for preparing a deacidifying adsorbent for phosphate ester fire-resistant oil according to claim 8, characterized in that, The drying conditions are: drying at 100~120℃ for 2~4 hours; the calcination conditions are: calcination at 400~600℃ for 3~5 hours.

10. The application of a deacidifying adsorbent according to any one of claims 1 to 7 in the deacidification treatment of phosphate ester fire-resistant fuel, characterized in that, The conditions for the deacidification treatment are as follows: the amount of deacidification adsorbent added is 1% to 5% of the weight of phosphate ester fire-resistant oil, the treatment temperature is 40 to 60°C, and the treatment time is 2 to 4 hours.