Preparation method of a supported solid base catalyst for producing propylene glycol by ester exchange method

Abstract

The present invention discloses a method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method, comprising the following steps: (1) uniformly mixing steel slag, glass powder, calcium carbonate and a binder, granulating the mixture, and then sintering the mixture in an air atmosphere at a temperature higher than the melting temperature of the glass powder; cooling the mixture to room temperature, and then placing the obtained porous sintered body in an acid solution for modification, thereby obtaining a catalyst precursor for standby use. (2) placing the catalyst precursor in an anhydrous ethanol solution containing a silane coupling agent, keeping the solution warm, and drying the solution after completion, thereby obtaining the supported solid base catalyst. The above method of the present invention not only helps to improve the water resistance of the supported solid base catalyst, but also improves the binding ability of the solid base catalyst component on the inert carrier, thereby increasing the service life of the catalyst.

Description

Technical Field

[0001] The invention relates to the technical field of propylene glycol preparation, in particular to a method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method. Background Art

[0002] Propylene glycol is a colorless, viscous liquid that is nearly odorless, with a slightly sweet smell and strong hygroscopicity. It is miscible with water, ethanol, and various organic solvents. It is an important organic chemical intermediate used primarily in the pharmaceutical, food, and cosmetic industries. Currently, most domestic manufacturers produce propylene glycol using the transesterification method, which uses propylene carbonate and anhydrous methanol as raw materials. Propylene glycol undergoes a transesterification reaction under the presence of a catalyst and heating. The traditional catalyst, sodium methoxide, is a homogeneous catalyst. After propylene glycol production, it is difficult to separate from the product, resulting in catalyst loss and difficulty in recycling. Therefore, heterogeneous solid catalysts have emerged. Supported solid base catalysts are a common type of heterogeneous solid catalyst. For example, solid base catalytic components (such as calcium oxide and potassium oxide) are supported on an inert support. However, these solid base catalytic components are sensitive to H2O and are easily poisoned and deactivated by H2O, resulting in the catalyst's inability to fully exert its catalytic effect. In addition, the solid base catalytic component on the inert carrier is easily lost during use, resulting in a short service life of the catalyst, the need for frequent catalyst replacement, and an increase in production costs. Summary of the Invention

[0003] To address the above-mentioned issues, the present invention provides a method for preparing a supported solid base catalyst for producing propylene glycol via the transesterification process. This method not only helps improve the water resistance of the supported solid base catalyst, but also enhances the binding capacity of the solid base catalyst component on the inert carrier, thereby increasing the service life of the catalyst. To achieve the above-mentioned objectives, the present invention discloses the following scheme.

[0004] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0005] (1) Steel slag powder is treated with acid to obtain modified steel slag powder. The modified steel slag powder, glass powder, calcium carbonate, and a binder are uniformly mixed and granulated. The granulated powder is then sintered in an air atmosphere at a temperature higher than the melting point of the glass powder. After cooling to room temperature, a catalyst precursor is obtained.

[0006] (2) The catalyst precursor is placed in an anhydrous ethanol solution containing a silane coupling agent and kept warm. After completion, the solution is dried to obtain the supported solid base catalyst.

[0007] Furthermore, in step (1), the ratio of the steel slag powder to the acid solution is 1g:30-50ml. Optionally, the mass fraction of the acid solution is 20-35%. Optionally, the acid solution includes any one of hydrochloric acid, sulfuric acid, etc.

[0008] Furthermore, in step (1), the acid treatment time is 1 to 1.5 hours to remove soluble components in the porous sintered body.

[0009] Furthermore, in step (1), the ratio of the modified steel slag powder, glass powder, calcium carbonate, and binder is 30-40 parts by weight: 5-7 parts by weight: 8-13 parts by weight: 14-17 parts by weight.

[0010] Furthermore, in step (1), the binder includes any one of starch, glue, cyclodextrin, shellac, water glass, etc.

[0011] Furthermore, in step (1), the sintering treatment temperature is 900-980° C., and the sintering time is 40-60 min.

[0012] Furthermore, in step (1), the melting temperature of the glass powder is lower than 890° C., so that the steel slag can be bonded together to form an inert catalyst carrier after melting during the sintering process.

[0013] Furthermore, in step (2), the mass fraction of the silane coupling agent in the anhydrous ethanol solution is 15-22%.

[0014] Furthermore, in step (2), the ratio of the catalyst precursor to the anhydrous ethanol solution containing the silane coupling agent is 1 g: 15-25 ml. Optionally, the silane coupling agent includes any one of silane coupling agents KH550, KH560, KH570, etc.

[0015] Furthermore, in step (2), the holding temperature is 50-70° C. and the holding time is 30-45 min, so as to graft the silane coupling agent onto the catalyst precursor and improve its water resistance.

[0016] Furthermore, in step (2), the drying temperature is 80-90° C. and the drying time is 5-10 min to remove the residual ethanol in the catalyst precursor.

[0017] Compared with the prior art, the present invention has achieved the following beneficial technical effects: In response to the problems existing in the current supported solid base catalyst mentioned in the above background technology, the present invention first uses steel slag, glass powder, calcium carbonate and a binder as raw materials, and calcines them at a high temperature under conditions higher than the melting temperature of the glass powder. During this process, the steel slag is bonded together under the action of molten glass to form an inert carrier. The solid base catalytic component formed after the decomposition of the calcium carbonate - calcium oxide is loaded on the inert carrier. At the same time, these calcium oxides are bonded to the inert carrier under the action of the molten glass. When cooled to room temperature, the molten glass powder solidifies and hardens again, thereby firmly fixing the calcium oxide on the inert carrier to prevent it from falling off during use. In addition, the binder is decomposed into gaseous products during the sintering process and then discharged from the inert carrier, thereby forming a porous inert carrier, which is convenient for increasing the exposed calcium oxide on the one hand and facilitating the contact area between the reaction raw materials and the catalyst during the catalytic reaction on the other hand, thereby improving the catalytic effect. Finally, the present invention performs a hydrophobic modification on the catalyst to reduce the entry of moisture into the catalyst and prevent the calcium oxide from being poisoned and inactivated. DETAILED DESCRIPTION

[0018] It should be noted that the following detailed descriptions are illustrative and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs.

[0019] It should be noted that the terms used herein are intended only to describe specific embodiments and are not intended to limit exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular is intended to include the plural. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they specify the presence of features, steps, operations, devices, components, and / or combinations thereof. The present invention will now be further described through specific implementations. Example 1

[0020] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0021] (1) 200-mesh steel slag powder and 30% hydrochloric acid were mixed in a ratio of 1 g:40 ml, stirred evenly, and allowed to stand for 1.5 hours to obtain modified steel slag powder.

[0022] (2) The modified steel slag powder, glass powder (melting temperature between 870°C and 890°C), calcium carbonate, and water glass binder are mixed in a ratio of 35 parts by weight: 6 parts by weight: 11 parts by weight: 15 parts by weight, and stirred uniformly. The mixture is then wet granulated. The resulting pellets are then sintered in an air atmosphere (temperature 950°C, time 50 minutes). After sintering, the pellets are cooled to room temperature to obtain a catalyst precursor.

[0023] (3) The catalyst precursor was mixed evenly with an anhydrous ethanol solution containing 20% ​​of the silane coupling agent KH560 in a ratio of 1 g:20 ml, and then kept warm at 60°C for 40 minutes. After completion, the solid product was separated and dried at 90°C for 5 minutes to obtain the supported solid base catalyst. Example 2

[0024] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0025] (1) 220-mesh steel slag powder and 20% sulfuric acid were mixed in a ratio of 1 g:50 ml, stirred evenly, and allowed to stand for 1 hour to obtain modified steel slag powder.

[0026] (2) The modified steel slag powder, glass powder (melting temperature between 850 and 860°C), calcium carbonate, and corn starch binder are mixed in a ratio of 40 parts by weight: 7 parts by weight: 13 parts by weight: 17 parts by weight, stirred evenly, and granulated according to a wet method. The resulting pellets are then sintered in an air atmosphere (temperature 900°C, time 60 minutes). After completion, the pellets are cooled to room temperature to obtain a catalyst precursor.

[0027] (3) The catalyst precursor was mixed evenly with an anhydrous ethanol solution containing 15% of the silane coupling agent KH550 in a ratio of 1 g:25 ml, and then kept warm at 50°C for 45 minutes. After completion, the solid product was separated and dried at 85°C for 10 minutes to obtain the supported solid base catalyst. Example 3

[0028] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0029] (1) 250-mesh steel slag powder and 35% hydrochloric acid were mixed in a ratio of 1 g:30 ml, stirred evenly, and allowed to stand for 1.5 hours to obtain modified steel slag powder.

[0030] (2) The modified steel slag powder, glass powder (melting temperature between 750 and 780°C), calcium carbonate, and cyclodextrin binder are mixed in a ratio of 30 parts by weight: 5 parts by weight: 8 parts by weight: 14 parts by weight, stirred evenly, and granulated according to a wet method. The resulting pellets are then sintered in an air atmosphere (temperature 980°C, time 40 minutes). After completion, the pellets are cooled to room temperature to obtain a catalyst precursor.

[0031] (3) The catalyst precursor was mixed evenly with an anhydrous ethanol solution containing 22% of the silane coupling agent KH570 in a ratio of 1 g:15 ml, and then kept warm at 70°C for 30 minutes. After completion, the solid product was separated and dried at 80°C for 10 minutes to obtain the supported solid base catalyst. Example 4

[0032] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0033] (1) 200-mesh steel slag powder and 30% hydrochloric acid were mixed in a ratio of 1 g:40 ml, stirred evenly, and allowed to stand for 1.5 hours to obtain modified steel slag powder.

[0034] (2) The modified steel slag powder, glass powder (melting temperature between 870°C and 890°C), calcium carbonate, and water glass binder are mixed in a ratio of 35 parts by weight: 6 parts by weight: 11 parts by weight: 15 parts by weight, and stirred uniformly, and granulated according to a wet method. The resulting granules are then sintered in an air atmosphere (temperature 950°C, time 50 minutes). After completion, the granules are cooled to room temperature to obtain the supported solid base catalyst. Example 5

[0035] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0036] (1) 250-mesh steel slag powder, glass powder (melting temperature between 750 and 780°C), calcium carbonate, and cyclodextrin binder were mixed in a ratio of 30 parts by weight: 5 parts by weight: 8 parts by weight: 14 parts by weight, stirred evenly, and granulated according to a wet method. The resulting pellets were then sintered in an air atmosphere (temperature 980°C, time 40 minutes). After completion, the pellets were cooled to room temperature to obtain a catalyst precursor.

[0037] (2) The catalyst precursor was mixed evenly with an anhydrous ethanol solution containing 22% of the silane coupling agent KH570 in a ratio of 1 g:15 ml, and then kept warm at 70°C for 30 minutes. After completion, the solid product was separated and dried at 80°C for 10 minutes to obtain the supported solid base catalyst. Example 6

[0038] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0039] (1) 220-mesh steel slag powder and 20% sulfuric acid were mixed in a ratio of 1 g:50 ml, stirred evenly, and allowed to stand for 1 hour to obtain modified steel slag powder.

[0040] (2) The modified steel slag powder, calcium carbonate, and corn starch binder were mixed in a ratio of 40 parts by weight: 13 parts by weight: 17 parts by weight, stirred evenly, and granulated according to a wet method. The resulting pellets were then sintered in an air atmosphere (temperature 900°C, time 60 minutes). After completion, the pellets were cooled to room temperature to obtain a catalyst precursor.

[0041] (3) The catalyst precursor was mixed evenly with an anhydrous ethanol solution containing 15% of the silane coupling agent KH550 in a ratio of 1 g:25 ml, and then kept warm at 50°C for 45 minutes. After completion, the solid product was separated and dried at 85°C for 10 minutes to obtain the supported solid base catalyst. Example 7

[0042] A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method comprises the following steps:

[0043] (1) 200-mesh steel slag powder and 30% hydrochloric acid were mixed in a ratio of 1 g:40 ml, stirred evenly, and allowed to stand for 1.5 hours to obtain modified steel slag powder.

[0044] (2) The modified steel slag powder, glass powder (melting temperature between 870 and 890°C), and calcium carbonate were mixed in a ratio of 35 parts by weight: 6 parts by weight: 11 parts by weight, stirred evenly, and granulated according to a wet method. The resulting pellets were then sintered in an air atmosphere (temperature 950°C, time 50 minutes). After completion, the pellets were cooled to room temperature to obtain a catalyst precursor.

[0045] (3) The catalyst precursor was mixed evenly with an anhydrous ethanol solution containing 20% ​​of the silane coupling agent KH560 in a ratio of 1 g:20 ml, and then kept warm at 60°C for 40 minutes. After completion, the solid product was separated and dried at 90°C for 5 minutes to obtain the supported solid base catalyst.

[0046] The supported solid base catalysts prepared in Examples 1-7 were used in a process for preparing dimethyl carbonate and co-producing propylene glycol using propylene carbonate and anhydrous methanol as raw materials. The conversion rate of propylene carbonate was calculated. The test results are based on the results of three consecutive reuses of the catalysts in the corresponding examples, as shown in the table below. It can be seen that the supported solid base catalysts prepared by the processes of Examples 1-3 maintained good catalytic performance after repeated reuse. However, the supported solid base catalysts prepared by the processes of Examples 4-7 showed a significant decrease in catalytic performance after repeated reuse.

[0047]

[0048] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. A method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange process, characterized in that: Including steps: (1) treating steel slag powder with an acid solution to obtain modified steel slag powder, uniformly mixing the modified steel slag powder, glass powder, calcium carbonate and a binder, and then granulating the mixture, and then sintering the mixture in an air atmosphere at a temperature higher than the melting temperature of the glass powder; cooling the mixture to room temperature to obtain a catalyst precursor; the acid solution is hydrochloric acid; (2) The catalyst precursor is placed in an anhydrous ethanol solution containing a silane coupling agent and kept warm. After completion, the solution is dried to obtain the supported solid base catalyst.

2. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (1), the ratio of the steel slag powder to the acid solution is 1g:30~50ml.

3. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (1), the mass fraction of the acid solution is 20-35%.

4. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (1), the ratio of the steel slag, glass powder, calcium carbonate and binder is 30-40 parts by weight: 5-7 parts by weight: 8-13 parts by weight: 14-17 parts by weight.

5. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (1), the binder is selected from any one of starch, glue, cyclodextrin, shellac, and water glass.

6. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (1), the sintering temperature is 900-980°C and the sintering time is 40-60 minutes.

7. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 6, characterized in that: In step (1), the melting temperature of the glass powder is lower than 890°C.

8. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (1), the modification treatment time is 1 to 1.5 hours.

9. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 1, wherein: In step (2), the mass fraction of the silane coupling agent in the anhydrous ethanol solution is 15-22%.

10. The method for preparing a supported solid base catalyst for producing propylene glycol by the transesterification method according to claim 9, characterized in that: In step (2), the ratio of the catalyst precursor to the anhydrous ethanol solution containing the silane coupling agent is 1 g: 15-25 ml.

11. The method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method according to claim 1, characterized in that: In step (2), the silane coupling agent is selected from any one of silane coupling agents KH550, KH560, and KH570.

12. The method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method according to any one of claims 1 to 11, characterized in that: In step (2), the insulation temperature is 50-70°C and the time is 30-45 minutes.

13. The method for preparing a supported solid base catalyst for producing propylene glycol by an ester exchange method according to any one of claims 1 to 11, characterized in that: In step (2), the drying temperature is 80-90°C and the drying time is 5-10 minutes.

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