A process for the preparation of acrolein from glycerol

Abstract

The application provides a method for preparing acrolein from glycerol. The method comprises the following steps: mixing raw materials containing glycerol, water and nitrile substances, contacting with a catalyst, and reacting to obtain a product containing acrolein. The catalyst is a silicon-aluminum molecular sieve, and the raw material liquid is a mixture of glycerol, water and nitrile substances. By adding nitrile substances to the raw material liquid, the selectivity of the target product can be significantly improved. Moreover, the silicon-aluminum molecular sieve catalyst used in the method is easy to obtain, and has strong practicability.

Description

Technical Field

[0001] This application relates to a method for preparing acrolein from glycerol, belonging to the field of acrolein preparation technology. Background Technology

[0002] Acrolein is the simplest unsaturated aldehyde, chemically reactive, and an important chemical intermediate, mainly used in the synthesis of acrylic acid, 1,3-propanediol, and the feed additive methionine. Currently, acrolein is primarily produced industrially through propylene oxidation. With the dwindling fossil fuel resources, finding a renewable energy production route to replace traditional acrolein production has become an urgent problem. Utilizing glycerol, a byproduct of the biodiesel industry, to produce acrolein is a promising route. Compared to propylene oxidation, glycerol, as a byproduct of the biodiesel industry, is a renewable resource, aligning with national requirements for sustainable and low-carbon development. Summary of the Invention

[0003] This application discloses a method for preparing acrolein, which uses aluminosilicate molecular sieves as catalysts and glycerol as reactants. By adjusting the ratio of glycerol, water and nitriles in the raw material solution, the selectivity of acrolein can be effectively improved.

[0004] According to one aspect of this application, a method for preparing acrolein from glycerol is provided, comprising the following steps:

[0005] A mixture of raw materials containing glycerol, water, and nitriles is brought into contact with a catalyst and reacted to obtain a product containing acrolein.

[0006] The nitrile substance is selected from at least one of acetonitrile, butyronitrile, and adiponitrile.

[0007] The catalyst is a silica-alumina molecular sieve;

[0008] The silica-aluminum molecular sieve is selected from at least one of ZSM-5 molecular sieve, Y-type molecular sieve, and Beta molecular sieve.

[0009] The silica-alumina ratio of the silica-alumina molecular sieve is 5 to 150;

[0010] Optionally, the silica-alumina molecular sieve has a silica-alumina ratio of 10 to 100.

[0011] The weight ratio of glycerol, water, and nitrile is (15:84:1) to (35:60:5).

[0012] Optionally, the upper limit of the weight ratio of glycerol, water and nitrile is selected from (35:60:5), (30:66:4), and (25:72:3), and the lower limit is selected from (15:84:1), (20:78:2), and (25:72:3);

[0013] The reaction is carried out in a fixed-bed reactor.

[0014] The reaction temperature is 300–500°C;

[0015] Optionally, the reaction temperature is any value or a range between 300°C, 320°C, 340°C, 360°C, 380°C, 400°C, 420°C, 440°C, 460°C, 480°C, and 500°C.

[0016] The reaction pressure is 0.5–3 MPa.

[0017] The mass hourly space velocity (MSV) of the glycerol is 0.5–10.5 h⁻¹. -1 .

[0018] Optionally, the mass hourly space velocity (WHSV) of the glycerol is 0.5 h⁻¹. -1 1h -1 2h -1 3h -1 4h -1 5h -1 6h -1 7h -1 8h -1 9h -1 10h -1 10.5h -1 Any value in the range or any value between the two.

[0019] The carrier gas for the reaction is nitrogen.

[0020] The flow rate of the nitrogen gas is 10–30 mL / min.

[0021] Unless otherwise stated, in the context of this application, the terms "silicon-to-aluminum ratio" and "Si / Al" refer to the molar ratio of silicon to aluminum.

[0022] The beneficial effects of this application include, but are not limited to:

[0023] (1) The method for preparing acrolein provided in this application uses silica-alumina molecular sieve as a catalyst, the raw materials are readily available, and it can be applied to large-scale production.

[0024] (2) The method for preparing acrolein provided in this application can effectively improve the conversion rate of glycerol and the yield of acrolein by controlling the ratio of the reaction raw materials glycerol, water and nitrile substances. Detailed Implementation

[0025] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0026] Unless otherwise specified, all raw materials used in this application were purchased commercially and used directly without special treatment.

[0027] Product composition analysis was performed using an Agilent 7890B gas chromatograph (FID detector, FFAP capillary column).

[0028] Comparative Example

[0029] Take 1.0 g of HZSM-5 molecular sieve (Si / Al = 30) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 320℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol to water is 15:85, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1 The reaction was carried out at atmospheric pressure with a nitrogen flow rate of 20 mL / min for 60 min. The results showed a conversion rate of 86% and an acrolein yield of 60%.

[0030] Example 1

[0031] Take 1.0 g of HZSM-5 molecular sieve (Si / Al = 30) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 320℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol, water, and acetonitrile is 15:84:1, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1 The pressure was at atmospheric pressure, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 60 min. The reaction results are shown in Table 1.

[0032] Example 2

[0033] Take 1.0 g of HZSM-5 molecular sieve (Si / Al = 30) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 320℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol, water, and acetonitrile is 25:72:3, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1 The pressure was at atmospheric pressure, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 60 min. The reaction results are shown in Table 1.

[0034] Example 3

[0035] Take 1.0 g of HY molecular sieve (Si / Al = 10) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 320℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol, water, and acetonitrile is 15:84:1, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1The pressure was at atmospheric pressure, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 60 min. The reaction results are shown in Table 1.

[0036] Example 4

[0037] Take 1.0 g of HY molecular sieve (Si / Al = 10) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 320℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol, water, and acetonitrile is 25:72:3, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1 The pressure was at atmospheric pressure, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 60 min. The reaction results are shown in Table 1.

[0038] Example 5

[0039] Take 1.0 g of HZSM-5 molecular sieve (Si / Al = 30) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 320℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol, water, and acetonitrile is 30:66:4, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1 The pressure was at atmospheric pressure, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 60 min. The reaction results are shown in Table 1.

[0040] Example 6

[0041] Take 1.0 g of HZSM-5 molecular sieve (Si / Al = 30) that has been compressed and sieved through a 20-40 mesh, and load it into a fixed-bed reactor. Pre-treat it in nitrogen at 500℃ for 1 h. Once the temperature drops to 360℃, introduce the raw materials to begin the reaction. The weight ratio of glycerol, water, and acetonitrile is 25:72:3, and the mass hourly space velocity (HHSV) is 2.5 h⁻¹. -1 The pressure was at atmospheric pressure, the nitrogen flow rate was 20 mL / min, and the reaction was analyzed after 60 min. The reaction results are shown in Table 1.

[0042] Table 1

[0043]

[0044]

[0045] As can be seen from the table, adding nitrile substances can improve the conversion rate and the yield of the target product.

[0046] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A method for preparing acrolein from glycerol, characterized in that, Includes the following steps: A mixture of raw materials containing glycerol, water, and nitriles is brought into contact with a catalyst and reacted to obtain a product containing acrolein. The nitrile substance is acetonitrile; The catalyst is a silica-alumina molecular sieve; The silica-aluminum molecular sieve is selected from at least one of HZSM-5 molecular sieve and HY molecular sieve; The weight ratio of glycerol, water and nitrile is (15:84:1) to (35:60:5).

2. The method according to claim 1, characterized in that, The silica-alumina molecular sieve has a silica-alumina ratio of 5 to 150.

3. The method according to claim 1, characterized in that, The silica-alumina molecular sieve has a silica-alumina ratio of 10 to 100.

4. The method according to claim 1, characterized in that, The reaction is carried out in a fixed-bed reactor.

5. The method according to claim 1, characterized in that, The reaction temperature is 300~500℃; The reaction pressure is 0.5~3 MPa.

6. The method according to claim 1, characterized in that, The mass hourly space velocity (MSV) of the glycerol is 0.5–10.5 h⁻¹. -1 .

7. The method according to claim 1, characterized in that, The carrier gas for the reaction is nitrogen. The flow rate of the nitrogen gas is 10~30 mL / min.

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