Preparation method of a catalyst for producing propylene glycol and catalyst regeneration process

Abstract

The present invention discloses a preparation method of a catalyst for producing propylene glycol and a catalyst regeneration process. The preparation method of the catalyst comprises the following steps: (1) placing sponge iron in a solution containing a copper ion source and a magnesium ion source, standing, and then separating the sponge iron to obtain modified sponge iron; (2) placing the modified sponge in a reaction vessel filled with ammonia water, and placing it above the ammonia water, and then performing alkali steaming treatment on the modified sponge under closed and heating conditions, and obtaining a catalyst precursor after completion; (3) placing the catalyst precursor in a protective atmosphere for calcination treatment, and obtaining a catalyst after completion. The catalyst regeneration process comprises the step of placing the catalyst used in the process of preparing propylene glycol by transesterification in a carbon monoxide atmosphere for reduction reaction, and obtaining the catalyst after completion. The catalyst obtained by the above method of the present invention not only has high catalytic efficiency and good selectivity, but also is convenient for recovery and recycling.

Description

Technical Field

[0001] The present invention relates to the technical field of the preparation of propylene glycol, and particularly relates to a preparation method of a catalyst for producing propylene glycol and a catalyst regeneration process. Background Art

[0002] Propylene glycol is a colorless viscous and almost odorless liquid, with strong hygroscopicity and the characteristics of being miscible with various organic solvents such as water and ethanol. Propylene glycol is widely used in industries such as pharmaceuticals, food, daily chemicals, and tobacco. The production processes of propylene glycol include three categories: propylene oxide hydration method, 1,2-dichloropropane hydrolysis method, and transesterification method. Among them, the transesterification method is the main method currently used by enterprises. This method can not only produce propylene glycol, but also co-produce dimethyl carbonate, with the advantages of low cost and easy large-scale production. However, the chemical reaction for preparing propylene glycol by the transesterification method cannot proceed under conventional conditions and usually requires the catalysis of a catalyst. These catalysts include alkali metal oxides, carbonates, alcoholates, etc., but such catalysts are homogeneous catalysts, and there are difficulties in separating them from the products, which brings difficulties to reuse. For this reason, heterogeneous solid catalysts have emerged. Such catalysts load active catalytic components on carriers. However, such catalysts generally have problems such as low selectivity and poor reuse effect. Summary of the Invention

[0003] In view of the above problems, the present invention provides a preparation method of a catalyst for producing propylene glycol and a catalyst regeneration process, which not only has high catalytic efficiency and good selectivity, but also is convenient for recovery and recycling. To achieve the above object, the present invention discloses the following technical solutions.

[0004] First, the present invention discloses a preparation method of a catalyst for producing propylene glycol, including the steps of:

[0005] (1) Placing sponge iron in a solution containing a copper ion source and a magnesium ion source, standing, and then separating the sponge iron to obtain modified sponge iron for standby.

[0006] (2) Placing the modified sponge in a reaction container filled with ammonia water and above the ammonia water, and then performing alkali steaming treatment on the modified sponge under closed and heating conditions. After completion, a catalyst precursor is obtained for standby.

[0007] (3) Calcining the catalyst precursor in a protective atmosphere to obtain a catalyst.

[0008] Further, in step (1), the copper ion source includes at least one of copper chloride, copper sulfate, copper nitrate, copper acetate, etc. Optionally, the mass fraction of the copper ion source in the solution is 7-12%.

[0009] Furthermore, in step (1), the magnesium ion source includes at least one of magnesium chloride, magnesium sulfate, magnesium nitrate, magnesium acetate, etc. Optionally, the mass fraction of the magnesium ion source in the solution is 10-16%.

[0010] Furthermore, in step (1), the ratio of the sponge iron to the solution containing the copper ion source and the magnesium ion source is 1 g: 30-50 ml.

[0011] Furthermore, in step (1), the standing time is 20 to 30 minutes. During this process, the copper ions undergo a replacement reaction with the sponge iron, thereby converting the copper ions into copper elemental substance and loading it on the sponge iron. At the same time, the adsorption property of the sponge iron is utilized to achieve the loading of magnesium ions.

[0012] Furthermore, in step (2), the concentration of the ammonia water is 18-25%.

[0013] Furthermore, in step (2), the heating temperature is 60-70° C., and the alkali steaming treatment time is 15-25 min, thereby converting the magnesium ions adsorbed in the sponge iron into magnesium hydroxide.

[0014] Furthermore, in step (3), the calcination temperature is 700-820°C and the calcination time is 45-70 minutes. Optionally, the protective atmosphere includes any one of nitrogen, argon, etc.

[0015] Secondly, the present invention discloses a catalyst regeneration process, comprising the steps of placing the catalyst used in the process of preparing propylene glycol by ester exchange in a carbon monoxide atmosphere for a reduction reaction, and obtaining the catalyst after completion.

[0016] Furthermore, the reduction reaction temperature is 750-850° C., and the time is 1-1.5 hours.

[0017] Furthermore, the regeneration process further comprises the step of collecting the product carbon dioxide. Preferably, the carbon dioxide is used as a raw material for preparing propylene glycol from methanol and carbon dioxide.

[0018] Compared with the prior art, the present invention has achieved the following beneficial technical effects: the catalyst of the present invention uses sponge iron as a carrier, which is then placed in a solution containing a copper ion source and a magnesium ion source, thereby utilizing the sponge iron to undergo a replacement reaction with the copper ions, thereby loading copper elemental matter on the surface of the sponge iron, and at the same time, the present invention utilizes the adsorption property of the sponge iron to achieve the loading of magnesium ions. The present invention then further carries out an alkali steam treatment on the loaded copper elemental matter and magnesium ions, during which ammonia and water vapor form an alkali solution that converts the magnesium ions on the sponge iron into magnesium hydroxide, while the copper elemental matter does not react with ammonia and is thus retained. After further calcination, the magnesium hydroxide decomposes into magnesium oxide, and at the same time, the copper elemental matter further solid-dissolves with the sponge iron, increasing the binding force between the copper elemental matter, magnesium oxide and the sponge iron carrier, making it difficult to fall off. The catalyst prepared by the present invention not only contains a metal catalytic center provided by copper, but also contains an alkaline catalytic center provided by magnesium oxide, and the iron provided by the sponge iron itself forms a Lewis acid catalytic center, which makes the catalyst of the present invention have good catalytic efficiency. In addition, since the catalyst of the present invention uses sponge iron as the main carrier, magnetic recovery can be conveniently performed. After the catalyst is used, the elemental iron in the sponge iron carrier may react with water and oxygen in the raw materials to form iron oxide, thereby affecting the catalyst's catalytic efficiency. However, due to the unique characteristics of the catalyst prepared by the pump invention, the present invention can use carbon monoxide to reduce the iron oxide back to elemental iron, while the copper and magnesium oxide do not react with the carbon monoxide and are retained, thereby achieving catalyst regeneration. Furthermore, the carbon dioxide converted from the carbon monoxide can be used as a feedstock for the production of propylene glycol from methanol and carbon dioxide. DETAILED DESCRIPTION

[0019] 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.

[0020] 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

[0021] A method for preparing a catalyst for producing propylene glycol comprises the following steps:

[0022] (1) Place sponge iron particles in an aqueous solution containing copper chloride and magnesium chloride at a ratio of 1 g:45 ml, where the mass fraction of copper chloride is 10% and the mass fraction of magnesium chloride is 15%. Allow the reaction to stand for 25 minutes. After completion, filter and separate the sponge iron to obtain the modified sponge iron, which is then set aside.

[0023] (2) The modified sponge is placed in a reactor filled with 20% ammonia water by mass and placed above the ammonia water. The reactor is then sealed and heated to 70°C in a water bath for 20 minutes to perform alkaline steam treatment on the modified sponge. After completion, a catalyst precursor is obtained and set aside.

[0024] (3) The catalyst precursor is placed in nitrogen, heated to 780°C at a rate of 10°C / min and kept warm for 60 minutes, and the catalyst is obtained after completion. Example 2

[0025] A method for preparing a catalyst for producing propylene glycol comprises the following steps:

[0026] (1) Place sponge iron particles in an aqueous solution containing copper sulfate and magnesium sulfate at a ratio of 1 g to 50 ml, where the mass fraction of copper sulfate is 7% and the mass fraction of magnesium sulfate is 16%. Allow the reaction to stand for 20 minutes. After completion, filter and separate the sponge iron to obtain the modified sponge iron, which is then set aside.

[0027] (2) The modified sponge is placed in a reactor filled with 18% ammonia water by mass and placed above the ammonia water. The reactor is then sealed and heated to 65°C in a water bath for 15 minutes to perform alkaline steam treatment on the modified sponge. After completion, a catalyst precursor is obtained and set aside.

[0028] (3) The catalyst precursor is placed in nitrogen, heated to 820°C at a rate of 10°C / min and kept warm for 45 minutes, and the catalyst is obtained after completion. Example 3

[0029] A method for preparing a catalyst for producing propylene glycol comprises the following steps:

[0030] (1) Place sponge iron particles in an aqueous solution containing copper nitrate and magnesium nitrate at a ratio of 1 g to 30 ml, where the mass fraction of copper nitrate is 12% and the mass fraction of magnesium nitrate is 10%. Allow the reaction to stand for 25 minutes. After completion, filter and separate the sponge iron to obtain the modified sponge iron, which is then set aside.

[0031] (2) Place the modified sponge above the ammonia water in a reaction kettle filled with ammonia water with a mass fraction of 25%. Then, after sealing the reaction kettle, heat it in a water bath to 60 °C and keep it warm for 25 min to perform alkali steaming treatment on the modified sponge. After completion, obtain the catalyst precursor for standby.

[0032] (3) Place the catalyst precursor in nitrogen, heat it to 700 °C at a rate of 10 °C / min and keep it warm for 70 min. After completion, obtain the catalyst. Example 4

[0033] A regeneration process of a catalyst includes the following steps: Place the catalyst (prepared in the above Example 1) used in the process of preparing propylene glycol by transesterification in a carbon monoxide atmosphere, and heat it to 810 °C at a rate of 10 °C / min and keep it warm for 1 hour for a reduction reaction. After completion, cool it to room temperature to obtain the regenerated catalyst. Example 5

[0034] A regeneration process of a catalyst includes the following steps: Place the catalyst (prepared in the above Example 4) used in the process of preparing propylene glycol by transesterification in a carbon monoxide atmosphere, and heat it to 750 °C at a rate of 10 °C / min and keep it warm for 1.5 hours for a reduction reaction. After completion, cool it to room temperature to obtain the regenerated catalyst. Example 6

[0035] A regeneration process of a catalyst includes the following steps: Place the catalyst (prepared in the above Example 5) used in the process of preparing propylene glycol by transesterification in a carbon monoxide atmosphere, and heat it to 850 °C at a rate of 10 °C / min and keep it warm for 1 hour for a reduction reaction. After completion, cool it to room temperature to obtain the regenerated catalyst. Example 7

[0036] A preparation method of a catalyst for producing propylene glycol includes the following steps:

[0037] (1) According to the ratio of 1 g:30 ml, place sponge iron particles in an aqueous solution containing magnesium nitrate, where the mass fraction of magnesium nitrate is 10%. Then, let it stand and react for 25 min. After completion, filter and separate the sponge iron to obtain the modified sponge iron for standby.

[0038] (2) Place the modified sponge above the ammonia water in a reaction kettle filled with ammonia water with a mass fraction of 25%. Then, after sealing the reaction kettle, heat it in a water bath to 60 °C and keep it warm for 25 min to perform alkali steaming treatment on the modified sponge. After completion, obtain the catalyst precursor for standby.

[0039] (3) Place the catalyst precursor in nitrogen, heat it to 700 °C at a rate of 10 °C / min and hold for 70 min. After completion, the catalyst is obtained. Example 8

[0040] A method for preparing a catalyst for producing propylene glycol, comprising the following steps:

[0041] (1) Place sponge iron particles in an aqueous solution containing copper chloride at a ratio of 1 g:45 ml, where the mass fraction of copper chloride is 10%. Then let it stand and react for 25 min. After completion, filter and separate the sponge iron to obtain the modified sponge iron, which is reserved for later use.

[0042] (2) Place the modified sponge in a reaction kettle containing ammonia water with a mass fraction of 20%, and place it above the ammonia water. Then seal the reaction kettle and heat it in a water bath to 70 °C and hold for 20 min to perform alkali steaming treatment on the modified sponge. After completion, the catalyst precursor is obtained and reserved for later use.

[0043] (3) Place the catalyst precursor in nitrogen, heat it to 780 °C at a rate of 10 °C / min and hold for 60 min. After completion, the catalyst is obtained. Example 9

[0044] A method for preparing a catalyst for producing propylene glycol, comprising the following steps:

[0045] (1) Place sponge iron particles in an aqueous solution containing copper sulfate and magnesium sulfate at a ratio of 1 g:50 ml, where the mass fraction of copper sulfate is 7% and the mass fraction of magnesium sulfate is 16%. Then let it stand and react for 20 min. After completion, filter and separate the sponge iron to obtain the modified sponge iron, which is reserved for later use.

[0046] (2) Place the modified sponge in a reaction kettle containing ammonia water with a mass fraction of 18%, and place it above the ammonia water. Then seal the reaction kettle and heat it in a water bath to 65 °C and hold for 15 min to perform alkali steaming treatment on the modified sponge. After completion, the catalyst is obtained. Example 10

[0047] A method for preparing a catalyst for producing propylene glycol, comprising the following steps:

[0048] (1) Place sponge iron particles in an aqueous solution containing copper nitrate and magnesium nitrate at a ratio of 1 g:30 ml, where the mass fraction of copper nitrate is 12% and the mass fraction of magnesium nitrate is 10%. Then let it stand and react for 25 min. After completion, filter and separate the sponge iron to obtain the modified sponge iron, which is reserved for later use.

[0049] (2) Place the modified sponge in a reaction kettle filled with ammonia water with a mass fraction of 25%. After mixing evenly, seal the reaction kettle and heat it in a water bath to 60 °C and keep it warm for 25 min to perform alkali steaming treatment on the modified sponge. After completion, obtain a catalyst precursor for standby.

[0050] (3) Place the catalyst precursor in nitrogen, heat it to 700 °C at a rate of 10 °C / min and keep it warm for 70 min. After completion, obtain the catalyst.

[0051] Test the yield of propylene glycol and the selectivity for propylene glycol in the process of preparing dimethyl carbonate and co-producing propylene glycol by transesterification method (the raw materials are anhydrous methanol and carbon dioxide) of the catalysts prepared in the above Examples 1-10.

[0052] The test results are shown in Table 1 below.

[0053] Example Serial Number 1 2 3 4 5 6 7 8 9 10 Yield / % 94.02 93.11 94.76 92.43 91.64 90.22 85.19 82.83 87.26 90.48 Selectivity / % 81.39 78.14 82.68 81.07 78.46 77.21 63.54 59.27 68.72 75.36

[0054] It can be seen that after the catalysts used multiple times in Examples 4 to 6 are regenerated, the obtained regenerated catalysts still have good catalytic efficiency and selectivity. The catalytic efficiency and selectivity of the catalysts prepared in Examples 7 to 10 have decreased significantly compared with Examples 1 to 6.

[0055] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A preparation method of a catalyst for producing propylene glycol, characterized in that: It includes the following steps: (1) Place sponge iron in a solution containing a copper ion source and a magnesium ion source, let it stand still, and then separate the sponge iron to obtain modified sponge iron for standby; (2) Place the modified sponge iron in a reaction container filled with ammonia water and above the ammonia water, and then perform alkali steaming treatment on the modified sponge under closed and heating conditions. After completion, obtain a catalyst precursor for standby; (3) Calcinate the catalyst precursor in a protective atmosphere to obtain a catalyst after completion.

2. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (1), the copper ion source includes at least one of copper chloride, copper sulfate, copper nitrate, and copper acetate.

3. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (1), the mass fraction of the copper ion source in the solution is 7-12%.

4. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (1), the magnesium ion source includes at least one of magnesium chloride, magnesium sulfate, magnesium nitrate, and magnesium acetate.

5. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: The mass fraction of the magnesium ion source in the solution is 10-16%.

6. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (1), the ratio of the sponge iron to the solution containing the copper ion source and the magnesium ion source is 1 g: 30-50 ml.

7. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (1), the standing time is 20-30 min.

8. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (2), the ammonia water concentration is 18-25%.

9. The preparation method of the catalyst for producing propylene glycol according to claim 1, characterized in that: In step (2), the heating temperature is 60-70 °C, and the time for the alkali steaming treatment is 15-25 min.

10. The preparation method of the catalyst for producing propylene glycol according to any one of claims 1-9, characterized in that: In step (3), the temperature of the calcination treatment is 700-820 °C, and the time is 45-70 min.

11. The preparation method of the catalyst for producing propylene glycol according to any one of claims 1-9, characterized in that: In step (3), the protective atmosphere includes any one of nitrogen and argon.

12. A regeneration process of a catalyst, characterized in that: It includes the step: Place the catalyst used in the process of preparing propylene glycol by transesterification in a carbon monoxide atmosphere for a reduction reaction, and obtain it after completion; the catalyst is obtained by the preparation method of the catalyst for producing propylene glycol according to any one of claims 1-8.

13. The regeneration process of the catalyst according to claim 12, characterized in that: The temperature of the reduction reaction is 750-850 °C, and the time is 1-1.5 hours.

14. The regeneration process of the catalyst according to claim 12, characterized in that: The regeneration process further includes the step of collecting the product carbon dioxide.

15. The regeneration process of the catalyst according to claim 14, characterized in that: Use the carbon dioxide as a raw material for preparing propylene glycol from methanol and carbon dioxide.