Method for preparing propionic acid through carbonylation of ethanol
By using an acidic molecular sieve catalyst for the carbonylation of ethanol to produce propionic acid, the problems of catalyst carbon deposition and metal loss are solved, and the stability and product separation are simplified, making it suitable for large-scale production.
Patent Information
- Application Number
- CN202411615327.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-13
- Publication Date
- 2026-05-15
AI Technical Summary
Existing methods for producing propionic acid by carbonylation of ethanol are prone to catalyst carbon deposition and metal loss, resulting in poor stability. Furthermore, corrosive iodide auxiliaries need to be added, the reaction conditions are harsh, and product separation is difficult.
Acidic molecular sieve catalysts, such as ZSM-35, ZSM-11, and ZSM-5, are used for the carbonylation reaction of ethanol to avoid the use of precious metals and iodide auxiliaries. A fixed-bed reactor is used to simplify product separation.
This approach improves catalyst stability, reduces corrosivity, simplifies product separation, and makes it suitable for large-scale production.
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Figure BDA0005132070150000061
Abstract
Description
Technical Field
[0001] This application relates to a method for producing propionic acid by carbonylation of ethanol, which belongs to the field of catalytic chemistry. Background Technology
[0002] Propionic acid (CH3CH2COOH) is an important chemical product and organic intermediate, widely used in the synthesis of plastics, pharmaceuticals, pesticides, feed and flavor additives, and food preservatives. Currently, the main industrial production method for propionic acid is the Reppe process from BASF in Germany. This process uses nickel carbonyl as a catalyst, with ethylene, carbon monoxide, and water reacting at a temperature of 250–320℃ and a pressure of 10–30 MPa to produce propionic acid in one step. The Reppe process involves high reaction pressure, and propionic acid is highly corrosive under these conditions, requiring extremely sophisticated equipment. Ethanol carbonylation is another well-studied method for propionic acid preparation. Similar to the mature methanol carbonylation method, homogeneous ethanol carbonylation mainly uses noble metal complex catalysts such as Rh and Ir, and also requires the addition of iodide auxiliaries. In the homogeneous ethanol carbonylation method, not only are the noble metal catalysts expensive, but the reaction also produces severely corrosive iodide substances, and the reaction pressure is also high, requiring sophisticated equipment and presenting difficulties in product separation. The heterogeneous carbonylation of ethanol generally employs supported metal catalysts. The active component can be either noble metals or non-noble metals such as Zn, Pb, Sn, Cu, and Ni. While the heterogeneous carbonylation of ethanol can improve some of the problems of the homogeneous method, it still suffers from issues such as low catalyst stability, severe carbon deposition, and metal loss. Furthermore, it is difficult to avoid the addition of iodide promoters. Summary of the Invention
[0003] Currently, in the metal-catalyzed carbonylation of ethanol to propionic acid, the catalyst suffers from poor stability due to easy carbon deposition and metal loss, requiring the addition of iodide auxiliaries. Therefore, this application provides a method for the carbonylation of ethanol to propionic acid catalyzed by acidic molecular sieves. This method does not require the use of metals or iodide auxiliaries, has low system corrosivity, and the product is easily separated.
[0004] Based on this, this application provides a method for producing propionic acid by carbonylation of ethanol, comprising passing a raw material containing ethanol, carbon monoxide and water through a reactor supported on an acidic molecular sieve catalyst and reacting it under predetermined reaction conditions to obtain a product containing propionic acid.
[0005] A method for preparing propionic acid by carbonylation of ethanol, the method comprising:
[0006] Raw materials containing ethanol and carbon monoxide are passed through a reactor loaded with an acidic molecular sieve catalyst to react and obtain a product containing propionic acid.
[0007] The acidic molecular sieve catalyst is selected from at least one of the following: hydrogen-type ZSM-35 molecular sieve, hydrogen-type ZSM-11 molecular sieve, hydrogen-type ZSM-5 molecular sieve, hydrogen-type ZSM-57 molecular sieve, hydrogen-type ZSM-23 molecular sieve, hydrogen-type ZSM-22 acidic molecular sieve, and hydrogen-type MCM-22 molecular sieve.
[0008] The acidic molecular sieve catalyst is an acidic molecular sieve catalyst with a 10-membered ring channel structure.
[0009] The acidic molecular sieve catalyst is selected from at least one of the following: acidic molecular sieves with FER structure, acidic molecular sieves with MEL structure, acidic molecular sieves with MFI structure, acidic molecular sieves with MFS structure, acidic molecular sieves with MTT structure, acidic molecular sieves with TON structure, and acidic molecular sieves with MWW structure.
[0010] Optionally, the molar ratio of carbon monoxide to ethanol is 5:1 to 200:1.
[0011] Preferably, the molar ratio of carbon monoxide to ethanol is 30:1 to 100:1.
[0012] Optionally, the molar ratio of carbon monoxide to ethanol is selected from any value or a range between 5:1, 10:1, 20:1, 50:1, 75:1, 100:1, 125:1, 150:1, 175:1, and 200:1.
[0013] Optionally, the raw material further contains water, and the molar ratio of water to ethanol is 0:1 to 20:1.
[0014] Preferably, the molar ratio of water to ethanol is 0:1 to 5:1.
[0015] Optionally, the molar ratio of water to ethanol is selected from any value or a range between 0:1, 0.5:1, 1.0:1, 2.0:1, 3.0:1, 4.0:1, 5.0:1, 6.0:1, 7.0:1, 8.0:1, 9.0:1, 10.0:1, 12.0:1, 15.0:1, 17.5:1, and 20:1.
[0016] Optionally, the reaction temperature is 180–320°C.
[0017] Preferably, the reaction temperature is 230–280°C.
[0018] Optionally, the reaction temperature is selected from any value or a range between 180°C, 190°C, 200°C, 210°C, 220°C, 230°C, 240°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, 310°C, and 320°C.
[0019] Optionally, the reaction pressure is 2 to 10 MPa.
[0020] Preferably, the reaction pressure is 4–6 MPa.
[0021] Optionally, the pressure of the reaction is selected from any value of 2MPa, 3MPa, 4MPa, 5MPa, 6MPa, 7MPa, 8MPa, 9MPa, 10MPa or a range between any two.
[0022] Optionally, the mass hourly space velocity (WHSV) of ethanol is 0.05–1.0 h⁻¹. -1 .
[0023] Preferably, the mass hourly space velocity (MSV) of ethanol is 0.1–0.3 h⁻¹. -1 .
[0024] Optionally, the space velocity of ethanol is selected from 0.05 h⁻¹. -1 0.1h -1 0.15h -1 0.2h -1 0.25h -1 0.3h -1 0.35h -1 0.4h -1 0.45h -1 0.5h -1 0.55h -1 0.6h -1 0.65h -1 0.7h -1 0.75h -1 0.8h -1 0.85h -1 0.9h -1 0.95h -1 1.0h -1 Any value in the range or any value between the two.
[0025] Optionally, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the acidic molecular sieve catalyst is 10–200.
[0026] Preferably, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the acidic molecular sieve catalyst is 20–80.
[0027] Optionally, the silicon-aluminum ratio (SiO2 / Al2O3) of the acidic molecular sieve catalyst is selected from any value or a range between 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, 120, 140, 160, 180, and 200.
[0028] Optionally, the reactor is a fixed-bed reactor.
[0029] The beneficial effects that this application can produce include:
[0030] 1) This application proposes a new method for the carbonylation of ethanol to produce propionic acid using acidic molecular sieve catalysis.
[0031] 2) The propionic acid preparation method in this application has a catalyst system that does not contain metal and iodide additives, the reaction products are easy to separate from the catalyst, the gas phase reaction system has low corrosivity, the fixed bed process is easy to engineer, and it is suitable for large-scale single-unit production. Detailed Implementation
[0032] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.
[0033] The endpoints and any values of the ranges disclosed in this application are not limited to the precise ranges or values, but should be understood to include those approximations of such ranges or values. For numerical ranges, the endpoint values of the various ranges 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.
[0034] This application provides a method for producing propionic acid by carbonylation of ethanol, comprising passing a raw material containing ethanol, carbon monoxide and water through a reactor supported on an acidic molecular sieve catalyst and reacting it under predetermined reaction conditions to obtain a product containing propionic acid.
[0035] The reaction equation for the carbonylation of ethanol to propionic acid catalyzed by acidic molecular sieves is as follows:
[0036] CH3CH2OH + CO = CH3CH2COOH
[0037] At the same time, propionic acid and ethanol react to produce a small amount of ethyl propionate:
[0038] CH3CH2COOH+CH3CH2OH=CH3CH2COOCH3CH2+H2O
[0039] It will also be accompanied by side reactions such as ethanol dehydration to produce ethylene and ethylene hydrogen transfer to produce other hydrocarbons.
[0040] The above-mentioned mechanism of ethanol carbonylation to propionic acid is as follows: ethanol reacts with Brønsted acid (ZEO-H) on the acidic molecular sieve to generate surface ethoxylate (ZEO-CH2CH3) species; carbon monoxide inserts into the surface ethoxylate to form surface propionyl (ZEO-COCH2CH3) species; propionyl reacts with water to generate propionic acid (CH3CH2COOH), which is desorbed while Brønsted acid (ZEO-H) is reduced.
[0041] In some embodiments, the acidic molecular sieve catalyst comprises a shaped acidic molecular sieve catalyst.
[0042] In some embodiments, the shaped acidic molecular sieve catalyst contains binders such as alumina and silicon dioxide.
[0043] In some embodiments, the raw material contains components such as nitrogen, argon, helium, and hydrogen.
[0044] In some embodiments, the reactor is a fixed-bed reactor.
[0045] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially.
[0046] Unless otherwise specified, all test methods are standard and all instrument settings are those recommended by the manufacturer.
[0047] The analysis method in the embodiments of this application is as follows:
[0048] The products and unreacted raw materials were analyzed online using an Agilent 7890B gas chromatograph, with its FID detector connected to a PLOT-Q capillary column and its TCD detector connected to a Porapak Q packed column.
[0049] In the embodiments of this application, the conversion rate and selectivity are calculated as follows:
[0050] Both ethanol conversion and propionic acid selectivity are calculated based on the number of carbon moles. Because ethanol readily dehydrates to ethylene on acidic molecular sieves, ethylene is treated as a reactant when calculating conversion and selectivity.
[0051] Ethanol conversion rate = [(number of carbon moles of ethanol in feed) - (number of carbon moles of ethanol and ethylene in discharge)] ÷ (number of carbon moles of ethanol in feed) × 100%
[0052] Propionic acid selectivity = (number of carbon moles of propionic acid in the discharge) ÷ (number of carbon moles of all products) × 100% Note: All products do not include ethylene generated from the dehydration of ethanol.
[0053] Example 1
[0054] 2g of acidic H-ZSM-35 molecular sieve catalyst (SiO2 / Al2O3 = 40, 20-40 mesh particles) was loaded into a container with an inner diameter of [missing information]. In a fixed-bed reactor, the reactor interior contains Thermocouple sheaths were used. Carbon monoxide was fed via a mass flow meter, while ethanol and water were fed via a horizontal flow pump. The raw materials were mixed and preheated before entering the catalyst bed for reaction. The products were heated and analyzed online using gas chromatography. Reaction conditions, including reaction temperature (T), reaction pressure (P), molar ratio of carbon monoxide to ethanol (CO:C2H5OH), molar ratio of water to ethanol (H2O:C2H5OH), ethanol mass hourly space velocity (WHSV), and reaction results after one day (24h) of operation are shown in Table 1.
[0055] Examples 2-10
[0056] Except for the changes in catalyst and reaction conditions, the experimental steps and apparatus of Examples 2 to 10 are the same as those of Example 1. The reaction conditions and reaction results after running for one day (24 hours) are shown in Table 1.
[0057] Comparative Example 1
[0058] The catalyst in Example 1 was replaced with H-MOR silica molecular sieve (SiO2 / Al2O3 = 15), and the experimental steps and apparatus were the same as in Example 1. The reaction conditions and reaction results after one day (24h) are shown in Table 1.
[0059] Comparative Example 2
[0060] The catalyst in Example 1 was replaced with a Py / H-MOR pyridine adsorption silicate molecular sieve (SiO2 / Al2O3 = 15). Py / H-MOR was prepared by treating H-MOR at 280°C and atmospheric pressure with a mixture of pyridine and nitrogen at a flow rate of 500 ml / min for 6 hours until adsorption saturation. Other experimental procedures and apparatus were consistent with Example 1. The reaction conditions and results after one day (24 h) of operation are shown in Table 1.
[0061] Table 1. Ethanol carbonylation reaction conditions and results of Examples 1-10 and Comparative Examples 1-2
[0062]
[0063] Note: Product selectivity <0.1% means that the product is hardly generated.
[0064] 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 fall within the scope of the technical solution.
Claims
1. A method for preparing propionic acid by carbonylation of ethanol, characterized in that, The method includes: Raw materials containing ethanol and carbon monoxide are passed through a reactor loaded with an acidic molecular sieve catalyst to react and obtain a product containing propionic acid. The acidic molecular sieve catalyst is selected from at least one of the following: hydrogen-type ZSM-35 molecular sieve, hydrogen-type ZSM-11 molecular sieve, hydrogen-type ZSM-5 molecular sieve, hydrogen-type ZSM-57 molecular sieve, hydrogen-type ZSM-23 molecular sieve, hydrogen-type ZSM-22 acidic molecular sieve, and hydrogen-type MCM-22 molecular sieve.
2. The method according to claim 1, characterized in that, The molar ratio of carbon monoxide to ethanol is 5:1 to 200:1; Preferably, the molar ratio of carbon monoxide to ethanol is 30:1 to 100:
1.
3. The method according to claim 1, characterized in that, The raw material also contains water, and the molar ratio of water to ethanol is 0:1 to 20:1; Preferably, the molar ratio of water to ethanol is 0:1 to 5:
1.
4. The method according to claim 1, characterized in that, The reaction temperature is 180–320°C; Preferably, the reaction temperature is 230–280°C.
5. The method according to claim 1, characterized in that, The reaction pressure is 2–10 MPa; Preferably, the reaction pressure is 4–6 MPa.
6. The method according to claim 1, characterized in that, The mass hourly space velocity (MSV) of ethanol is 0.05–1.0 h⁻¹. -1 ; Preferably, the mass hourly space velocity (MSV) of ethanol is 0.1–0.3 h⁻¹. -1 .
7. The method according to claim 1, characterized in that, The silicon-aluminum molecular ratio (SiO2 / Al2O3) of the acidic molecular sieve catalyst is 10–200. Preferably, the silicon-to-aluminum ratio (SiO2 / Al2O3) of the acidic molecular sieve catalyst is 20–80.
8. The method according to claim 1, characterized in that, The reactor is a fixed-bed reactor.