Process for the regeneration of deactivated alumina and its use

Abstract

This invention relates to the field of deactivated alumina regeneration technology, and discloses a method for regenerating deactivated alumina and its application: (1) cleaning deactivated alumina by contacting it with a cleaning solvent to obtain purified alumina I; (2) purging the purified alumina I by contacting it with water vapor to obtain purified alumina II; (3) soaking the purified alumina II in an alkaline solution to obtain regenerated alumina. The method for regenerating deactivated alumina provided in this invention yields regenerated alumina with high activity and low production cost, effectively reducing environmental pollution problems caused by the treatment of deactivated activated alumina, and has good social benefits, making it suitable for industrial promotion.

Description

Technical Field

[0001] This invention relates to the field of deactivated alumina regeneration technology, specifically to a method for regenerating deactivated alumina and its application. Background Technology

[0002] Hydrogen peroxide is an ideal green oxidant, widely used in textiles, food, medical, electronics, aerospace, and environmental protection. In recent years, hydrogen peroxide has been extensively used in the production of bulk chemicals such as propylene oxide and caprolactam, with its production and usage growing rapidly.

[0003] The anthraquinone process is the primary method for industrial hydrogen peroxide production, accounting for over 95% of total capacity. This method uses anthraquinone as a carrier for cyclic hydrogenation, producing hydrogen peroxide through hydrogenation, oxidation, extraction, and post-treatment steps. Ideally, anthraquinone is not consumed during the cyclic production process, serving only as a hydrogen carrier. However, in actual production, various factors influence the process, resulting in the generation of many anthraquinone derivatives that cannot produce hydrogen peroxide or whose production capacity is negligible. These anthraquinone derivatives are collectively referred to in the industry as degradation products.

[0004] The formation of anthraquinone degradation products not only increases the consumption of expensive anthraquinone, but also causes changes in the physical and chemical properties of the hydrogen peroxide production working fluid, such as increased viscosity, increased resistance, increased density, and decreased surface tension. This affects the normal operation of the equipment, reduces the H2O2 production capacity of the working fluid, and affects the quality of the finished hydrogen peroxide. Therefore, it is necessary to regenerate the anthraquinone degradation products in the working fluid after a period of operation.

[0005] There are two main methods for regenerating anthraquinone degradation products: activated alumina regeneration and alkali regeneration. Domestic hydrogen peroxide manufacturers commonly use activated alumina regeneration to regenerate the degradation products generated during the recycling process. Activated alumina is for single use only; if deactivated activated alumina cannot be regenerated, it must be treated as hazardous waste.

[0006] Numerous studies have been conducted on the regeneration of deactivated alumina. For example, Qiu Fuguo et al. from Xi'an University of Architecture and Technology used aluminum sulfate of different concentrations to soak deactivated activated alumina for regeneration, but the regeneration effect was poor. The activated alumina obtained by Daqing Petrochemical Plant using acid activation and water washing also had relatively low activity.

[0007] Xu Zhibing and colleagues from the School of Chemistry and Materials Science at Anhui Normal University mixed crushed waste alumina with sodium carbonate and calcined it at high temperature, introducing carbon dioxide during the calcination process. While this method can yield activated alumina, it is complex and costly. Shenyang Catalyst Plant and Nanjing Refinery reacted waste alumina with acid, then neutralized it with ammonia water before calcining it to obtain activated alumina; this method is also complex and costly.

[0008] Therefore, there is an urgent need to provide a method for regenerating deactivated alumina that has good regeneration effect, simple process and low cost. Summary of the Invention

[0009] The purpose of this invention is to solve the problems of poor regeneration effect, complex process and high cost of deactivated alumina in the prior art, and to provide a method for regenerating deactivated alumina and its application. This method has the advantages of good regeneration effect, simple process and low cost.

[0010] To achieve the above objectives, a first aspect of the present invention provides a method for regenerating activated alumina, wherein the method includes the following steps:

[0011] (1) Clean the deactivated alumina by contacting it with a cleaning solvent to obtain purified alumina I;

[0012] (2) The purified alumina I is purged by contacting water vapor to obtain purified alumina II;

[0013] (3) The purified alumina II is soaked in alkaline solution to obtain recycled alumina.

[0014] The second aspect of the present invention provides the application of the method described in the first aspect of the present invention in the regeneration of hydrogen peroxide-deactivated alumina produced by the anthraquinone process.

[0015] The beneficial technical effects achieved by the present invention through the above technical solution are as follows:

[0016] 1) The regeneration method for deactivated alumina provided in this invention can basically restore the pore structure, specific surface area and alkaline centers of activated alumina, thereby improving the activity of the regenerated catalyst;

[0017] 2) The method for regenerating deactivated alumina provided in this invention can effectively utilize the existing conditions of hydrogen peroxide equipment for online regeneration, which can simplify the process and reduce production costs;

[0018] 3) The method for regenerating deactivated alumina provided in this invention has low production cost, can effectively reduce the environmental pollution caused by the treatment of deactivated alumina, has good social benefits, and is suitable for industrial promotion. Detailed Implementation

[0019] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0020] A first aspect of the present invention provides a method for regenerating activated alumina, wherein the method includes the following steps:

[0021] (1) Clean the deactivated alumina by contacting it with a cleaning solvent to obtain purified alumina I;

[0022] (2) The purified alumina I is purged by contacting water vapor to obtain purified alumina II;

[0023] (3) The purified alumina II is soaked in alkaline solution to obtain recycled alumina.

[0024] In this invention, the inventors discovered through research that the combined action of cleaning solvent, water vapor, and alkaline solution can regenerate deactivated alumina, especially deactivated alumina from the anthraquinone process for producing hydrogen peroxide, resulting in highly active regenerated alumina.

[0025] In step (1):

[0026] In a preferred embodiment, the activated alumina is derived from the anthraquinone process for producing hydrogen peroxide, and is deactivated alumina obtained by treating the anthraquinone degradation products in the working solution with activated alumina. The impurities contained in the deactivated alumina mainly include components of the hydrogen peroxide working solution, such as heavy aromatics, trioctyl phosphate, and anthraquinones.

[0027] In one embodiment of the present invention, the cleaning solvent is a heavy aromatic hydrocarbon, preferably selected from one or more of benzene, toluene, xylene, trimethylbenzene, and ethylbenzene. The present invention does not specifically limit xylene and trimethylbenzene, which can be o-xylene, m-xylene, p-xylene, or any mixture thereof. The trimethylbenzene can be 1,2,3-trimethylbenzene, 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, or any mixture thereof.

[0028] In one embodiment of the present invention, the ratio of the deactivated alumina to the cleaning solvent is 100g:400-1200mL, preferably 100g:600-1000mL.

[0029] In one embodiment of the present invention, the cleaning operation conditions include: a cleaning temperature of 40-120°C, preferably 60-120°C; and a cleaning time of 2-12 hours, preferably 4-6 hours.

[0030] In this invention, the cleaning temperature is not higher than the boiling point of the cleaning solvent at room temperature and pressure. The specific cleaning temperature can be adjusted according to the cleaning solvent, and this invention does not impose any special limitations.

[0031] In step (2):

[0032] In one embodiment of the present invention, the temperature of the water vapor is 100-180°C, preferably 100-150°C, and the pressure is 0.1-1 MPa, preferably 0.1-0.5 MPa.

[0033] In one embodiment of the present invention, the purging operating conditions include: a purging volumetric space velocity of 1-10 h⁻¹. -1 Preferably 2-6h -1 The purging time is 5-48 hours, preferably 20-28 hours.

[0034] In this invention, the purge volumetric space velocity refers to the volume ratio of the purge gas to the activated alumina per unit time. The inventors of this invention have discovered that by selecting low-pressure steam and controlling the purge conditions, the activity of the regenerated activated alumina can be improved while avoiding the damage caused to the activated alumina by the interaction of high-temperature steam with the alumina, thereby obtaining highly active regenerated alumina.

[0035] In step (3):

[0036] In one embodiment of the present invention, the purified alumina II is dried and then contacted with an alkaline solution to obtain regenerated alumina.

[0037] In one embodiment of the present invention, the alkaline solution is selected from sodium hydroxide solution and / or potassium hydroxide solution, preferably sodium hydroxide solution.

[0038] In one embodiment of the present invention, the concentration of alkali in the alkaline solution is 0.1-5 wt%, preferably 1-4 wt%.

[0039] In one embodiment of the present invention, the soaking conditions include: soaking at room temperature for 2-20 hours, preferably 4-10 hours.

[0040] In one embodiment of the present invention, after the soaking is completed, the mixture is filtered and dried in sequence to obtain recycled alumina.

[0041] In this invention, unless otherwise specified, drying is performed by nitrogen purging. The nitrogen purging operating conditions include: a nitrogen purging temperature of 60-140°C, preferably 100-120°C; and a nitrogen purging volume hourly space velocity of 50-400 h⁻¹. -1 Preferably 150-300h -1 The nitrogen purging time is 10-60 hours, preferably 24-48 hours.

[0042] The second aspect of the present invention provides the application of the method described in the first aspect of the present invention in the regeneration of hydrogen peroxide-deactivated alumina produced by the anthraquinone process.

[0043] The present invention will be described in detail below through embodiments.

[0044] The deactivated alumina in the examples and comparative examples came from the 150,000-ton / year 50wt% hydrogen peroxide production plant of Sinopec Changling Branch.

[0045] Example 1

[0046] (1) Place 100g of deactivated alumina in a reactor, and 800mL of cleaning agent toluene enters the reactor from bottom to top. The deactivated alumina and the cleaning solvent are contacted at 60℃ for 6h, and then separated to obtain purified alumina I.

[0047] (2) The above-mentioned purified alumina I is placed in a reactor, and water vapor (120°C, 0.2MPa) enters from top to bottom and contacts the purified alumina I for purging to obtain purified alumina II; wherein the water vapor purging volume hourly space velocity is 2h. -1 The purging time is 24 hours;

[0048] (3) The water vapor was replaced with nitrogen gas for the first nitrogen purging. The purified alumina II was dried and then soaked in a 2 wt% sodium hydroxide solution at room temperature for 6 hours. After soaking, the alumina II was filtered, and the filtered solid was subjected to a second nitrogen purging to obtain regenerated alumina. The temperature of the first nitrogen purging was 120°C and the nitrogen purging volume hourly space velocity was 150 h⁻¹. -1 The nitrogen purging time was 24 hours; the second nitrogen purging temperature was 120°C, and the nitrogen purging volume hourly space velocity was 300 h⁻¹. -1 The nitrogen purging time is 48 hours.

[0049] Example 2

[0050] (1) Place 100g of deactivated alumina in a reactor, and 600mL of cleaning agent toluene enters the reactor from bottom to top. The deactivated alumina and the cleaning solvent are contacted at 80℃ for 6h, and then separated to obtain purified alumina I.

[0051] (2) The above-mentioned purified alumina I is placed in a reactor, and water vapor (100℃, 0.1MPa) enters from top to bottom and contacts the purified alumina I for purging to obtain purified alumina II; wherein the water vapor purging volume hourly space velocity is 3h. -1 The purging time is 24 hours;

[0052] (3) The water vapor was replaced with nitrogen gas for the first nitrogen purging. The purified alumina II was dried and then soaked in a 1 wt% sodium hydroxide solution at room temperature for 6 hours. After soaking, the alumina II was filtered, and the filtered solid was subjected to a second nitrogen purging to obtain regenerated alumina. The temperature of the first nitrogen purging was 120°C and the nitrogen purging volume hourly space velocity was 150 h⁻¹. -1 The nitrogen purging time was 24 hours; the second nitrogen purging temperature was 120°C, and the nitrogen purging volume hourly space velocity was 300 h⁻¹. -1 The nitrogen purging time is 48 hours.

[0053] Example 3

[0054] (1) Place 100g of deactivated alumina in a reactor, and 1000mL of cleaning agent toluene enters the reactor from bottom to top. The deactivated alumina and the cleaning solvent are contacted at 100℃ for 4h, and then separated to obtain purified alumina I.

[0055] (2) The above-mentioned purified alumina I is placed in a reactor, and water vapor (150°C, 0.5MPa) enters from top to bottom and contacts the purified alumina I for purging to obtain purified alumina II; wherein the water vapor purging volume hourly space velocity is 3h. -1 The purging time is 24 hours;

[0056] (3) The water vapor was replaced with nitrogen gas for the first nitrogen purging. The purified alumina II was dried and then soaked in a 2 wt% sodium hydroxide solution at room temperature for 6 hours. After soaking, the alumina II was filtered, and the filtered solid was subjected to a second nitrogen purging to obtain regenerated alumina. The temperature of the first nitrogen purging was 120°C and the nitrogen purging volume hourly space velocity was 150 h⁻¹. -1 The nitrogen purging time was 24 hours; the second nitrogen purging temperature was 120°C, and the nitrogen purging volume hourly space velocity was 300 h⁻¹. -1 The nitrogen purging time is 48 hours.

[0057] Example 4

[0058] (1) Place 100g of deactivated alumina in a reactor, and 1000mL of cleaning agent ethylbenzene enters the reactor from bottom to top. The deactivated alumina and the cleaning solvent are contacted at 120℃ for 4h, and then separated to obtain purified alumina I.

[0059] (2) The above-mentioned purified alumina I is placed in a reactor, and water vapor (150°C, 0.5MPa) enters from top to bottom and contacts the purified alumina I for purging to obtain purified alumina II; wherein the water vapor purging volume hourly space velocity is 4h. -1 The purging time is 24 hours;

[0060] (3) The water vapor was replaced with nitrogen gas for the first nitrogen purging. The purified alumina II was dried and then soaked in a 4 wt% sodium hydroxide solution at room temperature for 6 hours. After soaking, the alumina II was filtered, and the filtered solid was subjected to a second nitrogen purging to obtain regenerated alumina. The temperature of the first nitrogen purging was 120°C and the nitrogen purging volume hourly space velocity was 150 h⁻¹. -1 The nitrogen purging time was 24 hours; the second nitrogen purging temperature was 120°C, and the nitrogen purging volume hourly space velocity was 300 h⁻¹. -1 The nitrogen purging time is 48 hours.

[0061] Example 5

[0062] (1) Place 100g of deactivated alumina in a reactor, and 600mL of cleaning agent ethylbenzene enters the reactor from bottom to top. The deactivated alumina and the cleaning solvent are contacted at 120℃ for 4h, and then separated to obtain purified alumina I.

[0063] (2) The above-mentioned purified alumina I is placed in a reactor, and water vapor (100℃, 0.1MPa) enters from top to bottom and contacts the purified alumina I for purging to obtain purified alumina II; wherein the water vapor purging volume hourly space velocity is 3h. -1 The purging time is 24 hours;

[0064] (3) The water vapor was replaced with nitrogen gas for the first nitrogen purging. The purified alumina II was dried and then soaked in a 3 wt% sodium hydroxide solution at room temperature for 6 hours. After soaking, the alumina II was filtered, and the filtered solid was subjected to a second nitrogen purging to obtain regenerated alumina. The temperature of the first nitrogen purging was 120°C and the nitrogen purging volume hourly space velocity was 150 h⁻¹. -1 The nitrogen purging time was 24 hours; the second nitrogen purging temperature was 120°C, and the nitrogen purging volume hourly space velocity was 300 h⁻¹. -1 The nitrogen purging time is 48 hours.

[0065] Comparative Example 1

[0066] Similar to Example 2, except that the water vapor purging in step (2) is different.

[0067] (2) The above-mentioned purified alumina I was placed in a reactor, and water vapor (235°C, 3.0 MPa) entered from top to bottom and contacted the purified alumina I for purging to obtain purified alumina II; the water vapor purging volume hourly space velocity was 3 h⁻¹. -1 The purging time is 24 hours.

[0068] Comparative Example 2

[0069] Similar to Example 3, except that the sodium hydroxide solution soaking and the second nitrogen purging in step (3) are omitted, that is, water vapor is replaced with nitrogen for the first nitrogen purging, and the above-mentioned purified alumina II is dried to obtain regenerated alumina.

[0070] The operating conditions in the examples and comparative examples are summarized in Table 1:

[0071] Table 1

[0072]

[0073] Test case

[0074] The physicochemical properties and activity evaluations of fresh alumina (from the 150,000 tons / year 50wt% hydrogen peroxide production unit of Sinopec Changling Branch), recycled alumina obtained in the examples and comparative examples were conducted, and the results are shown in Table 2:

[0075] Specific surface area and pore volume were tested using N2 physical adsorption-desorption characterization, particle strength was tested using a strength tester, and sodium oxide content was tested using X-ray fluorescence semi-quantitative full analysis.

[0076] The activity evaluation method for recycled alumina: The working fluid used in the evaluation test is the working fluid after hydrogenation and oxidation from the 150,000 tons / year 50wt% hydrogen peroxide production unit of Sinopec Changling Branch.

[0077] The regenerated alumina was placed in a fixed-bed reactor. At 60°C, the working fluid flowed upward through the regenerated alumina bed, with a volume hourly space velocity (VHSV) of 1.0 h⁻¹. -1 The regenerated working solution was obtained. The regenerated amount of effective anthraquinones (2-ethylanthraquinone and tetrahydro-2-ethylanthraquinone) was calculated by measuring the content of effective anthraquinones (2-ethylanthraquinone and tetrahydro-2-ethylanthraquinone) in the working solution and the regenerated working solution. The regenerated amount of effective anthraquinones is equal to the content of effective anthraquinones in 1L of regenerated working solution minus the content of effective anthraquinones in 1L of working solution.

[0078] Table 2

[0079] sample <![CDATA[Specific surface area, m 2 / g]]> Pore ​​volume, ml / g Strength, N / piece Sodium oxide content, % Effective anthraquinone regeneration capacity, g / L Fresh alumina 238 0.47 131 2.0 3.98 Deactivated alumina 92 0.23 121 0.8 Example 1 204 0.40 127 2.7 3.17 Example 2 196 0.37 130 1.8 2.98 Example 3 212 0.43 128 2.7 3.49 Example 4 229 0.46 129 4.5 3.63 Example 5 210 0.42 127 3.6 3.28 Comparative Example 1 150 0.31 124 1.8 0.81 Comparative Example 2 163 0.33 125 0.8 0.57

[0080] As shown in Table 2, most of the indicators of the regenerated activated alumina were restored. It can regenerate the degradation products in the working solution into effective anthraquinones, and the amount of effective anthraquinones regenerated is close to the level of fresh agents, which can meet the requirements of industrial use.

[0081] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for regenerating activated alumina, wherein, The method includes the following steps: (1) Clean the deactivated alumina by contacting it with a cleaning solvent to obtain purified alumina I; (2) The purified alumina I is purged by contacting water vapor to obtain purified alumina II; (3) After the purified alumina II is dried, it is soaked in alkaline solution. After the soaking is completed, it is filtered and dried in sequence to obtain recycled alumina. In step (1), the cleaning solvent is toluene and / or ethylbenzene; In step (1), the ratio of the amount of deactivated alumina to the amount of cleaning solvent is 100g: 800-1200mL; In step (1), the cleaning operation conditions include: a cleaning temperature of 80-120℃ and a cleaning time of 4-12h; In step (2), the temperature of the water vapor is 100-180℃ and the pressure is 0.1-1MPa; In step (3), the alkaline solution is a sodium hydroxide solution, and the concentration of the alkali in the alkaline solution is 0.1-5 wt%. In step (3), the drying process involves nitrogen purging. The operating conditions for nitrogen purging include: a nitrogen purging temperature of 100-120°C and a nitrogen purging volume hourly space velocity of 150-300 h⁻¹. -1 Nitrogen purging time is 24-48 hours.

2. The method according to claim 1, wherein, The temperature of the water vapor is 100-150℃ and the pressure is 0.1-0.5MPa.

3. The method according to claim 1 or 2, wherein, In step (2), the purging operating conditions include: a purging volumetric space velocity of 1-10 h⁻¹. -1 The purging time is 5-48 hours.

4. The method according to claim 3, wherein, In step (2), the purging operating conditions include: a purging volumetric space velocity of 2-6 h⁻¹. -1 The purging time is 20-28 hours.

5. The method according to claim 1 or 2, wherein, The soaking conditions include: soaking time of 2-20 hours at room temperature.

6. The method according to claim 1 or 2, wherein, The soaking conditions include: soaking time of 4-10 hours at room temperature.

7. The application of the method according to any one of claims 1-6 in the regeneration of deactivated alumina produced by the anthraquinone process.

Images