CN116803969B - Method for preparing acetic acid by using natural gas and carbon dioxide - Google Patents
Method for preparing acetic acid by using natural gas and carbon dioxideInfo
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- CN116803969B CN116803969B CN202210256133.XA CN202210256133A CN116803969B CN 116803969 B CN116803969 B CN 116803969B CN 202210256133 A CN202210256133 A CN 202210256133A CN 116803969 B CN116803969 B CN 116803969B
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Abstract
The invention discloses a method for preparing acetic acid by using natural gas and carbon dioxide, which takes methyl iodide and water vapor as catalysts to enable the carbon dioxide and the methane to react to generate reaction products, and the acetic acid product is obtained by separating the reaction products. The method provides a high yield acetic acid production process in which methane and carbon dioxide are directly reacted without additional reaction raw materials.
Description
Technical Field
The invention relates to a method for preparing acetic acid in the field of organic chemistry, in particular to a method for preparing acetic acid by utilizing natural gas and carbon dioxide.
Background
Acetic acid, also known as acetic acid, is an important feedstock in both the food industry and the chemical industry. Acetic acid, for example, can be used as an acidulant, flavoring and spice for vinegar, beverages, cans, and other seasonings, and the like. Acetic acid belongs to a large number of chemical products, is one of the most important organic acids, is widely applied to vinyl acetate, acetic anhydride, acetate fibers, metal acetate, acetate and the like, and has wide application in pesticide, medicine, dye, photography and rubber industries. With the rapid development of downstream industries such as vinyl acetate, biodegradable PBAT plastic and the like, the use amount of acetic acid is greatly increased, and the acetic acid becomes an important component of national economy.
The preparation method of acetic acid comprises a biological synthesis method and an artificial synthesis method, wherein the biological synthesis method is to prepare the acetic acid by utilizing bacterial fermentation, and the biological synthesis method only occupies a very small part of the yield of the acetic acid in the whole world at present, and most of the acetic acid is prepared by adopting an industrial synthesis method. Among industrial synthesis methods of acetic acid, an acetaldehyde method, an ethylene direct oxidation method, a methanol carbonylation method, and the like are experienced, and the most widely used method at present is the methanol carbonylation method for producing acetic acid. As early as 1925, selanis, UK developed the first pilot plant for the production of acetic acid by methylcarbonylation. In 1970, the us mendo company built a device using this process, so rhodium catalyzed methylcarbonylation to acetic acid became the dominant commercial mendo process for acetic acid. Later in the 90 s, the Cativa catalytic method is successfully commercialized by British petroleum, and the ruthenium catalyst is adopted, so that the environment-friendly efficiency is higher than that of Meng Shandou.
In the methanol carbonylation process, methanol is not a naturally occurring raw material, and needs to be industrially synthesized, and methanol and carbon monoxide have relatively high toxicity, so that more attention is paid to cost and safety when the two main raw materials are used for producing acetic acid.
The methane corresponding to the methanol is the organic compound with the simplest structure and is the main component naturally existing in the natural gas with rich reserves, the carbon dioxide corresponding to the carbon monoxide is also the gas existing in a large amount in the air, and simultaneously, a large amount of carbon dioxide is generated in industrial production and daily life of people, the toxicity is not great, and the treatment naturally has better return in terms of cost and safety. And the greenhouse effect influence caused by carbon dioxide is faced worldwide at present, and along with the control of carbon peak and carbon neutralization worldwide, the treatment of the excessive carbon dioxide is also urgently needed, and is an extremely important path from the aspect of changing waste into valuable.
While both theoretical and objective needs have desired to provide an industrial process for the rapid, simple production of acetic acid from methane (natural gas) and carbon dioxide, there has been little practical progress.
Although processes for the preparation of acetic acid involving gas phase reactions of methane and carbon monoxide and/or carbon dioxide containing iron or nickel carbonate in the presence of a catalyst at from 12 to 50 atmospheres and at from 120 to 300 ℃ have been disclosed in GB226248, 1924, 12, 22, publication date 1924, the contents of which are incorporated herein by reference in their entirety. However, the method has no reference to the application data in terms of raw material conversion rate, product yield, product purity and the like, and obviously does not reach the extent that the method can be popularized and applied in industry.
WO 96/05163A1 (publication date, month 2, 1996, 22, the contents of which are incorporated herein by reference in their entirety) discloses a process for the production of acetic acid comprising reacting methane and carbon dioxide at a temperature of 100 to 600 ℃ and a pressure of 0.1 to 20MPa using a catalyst comprising one or more group VIA, VIIA and/or VIIIA metals. However, the process is likewise silent about the application data in terms of conversion of the starting material, yield of the product, purity of the product, etc., only about the selectivity of acetic acid based on the starting material methane of 70 to 95%, and obviously not to the extent industrially applicable.
Chinese patent application CN1839110a (publication No. 2006, 9, 27, the contents of which are incorporated herein by reference in their entirety) discloses contacting methane and carbon dioxide in an anhydrous environment in the presence of a transition metal catalyst and a reaction promoter, as well as an anhydride compound and optionally an acid, to produce a product comprising acetyl anhydride, which upon further contact with water can recover acetic acid. However, this process uses additional acids and anhydrides, trifluoroacetic anhydride/acid, fuming sulfuric acid, trifluoromethanesulfonic anhydride/acid, etc., and reaction promoters such as K 2S2O8 and small amounts of VO (acac) 2, etc., with only 7-16% conversion based on methane, including the production of various by-products. Obviously, the method can not be popularized and applied industrially.
Chinese patent application CN1309114a (publication No. 2001, 8 and 22, the contents of which are incorporated herein by reference in their entirety) discloses a method for synthesizing acetic acid in a heterogeneous catalytic system, wherein CH 4 and CO 2 are used as raw materials, on a solid heterogeneous catalyst, acetic acid is synthesized by alternately feeding CH 4 and CO 2 or CH 4 and CO 2/H2, the reaction temperature is 100-600 ℃, the reaction pressure is normal pressure-20 Mpa, and the yield of the final product acetic acid is 0.020-0.137g/gcat. However, this method requires two steps and additional introduction of hydrogen for the reaction, and the catalytic system is heterogeneous, which has disadvantages in terms of catalytic efficiency and side reactions.
Disclosure of Invention
The invention aims to provide a high-yield acetic acid preparation method by directly reacting methane and carbon dioxide without additional reaction raw materials, which specifically comprises the following technical scheme:
The invention provides a method for preparing acetic acid by using natural gas and carbon dioxide, which is characterized in that methyl iodide and water vapor are used as catalysts, so that the carbon dioxide and the methane react to generate a reaction product, and the acetic acid is separated from the reaction product.
Preferably, the volume ratio of methane to carbon dioxide in the present invention is 0.5-2:1.
Preferably, the volume ratio of carbon dioxide to water vapor in the present invention is 3-6:1.
Preferably, the pressure of the reaction according to the invention is from atmospheric pressure to 20MPa.
Preferably, the temperature of the reaction according to the invention is in the range of 100 to 600 ℃.
It is further preferred that the catalyst methyl iodide according to the present invention participates in catalysis in a flowing liquid form.
Preferably, the method further comprises the step of recycling the gas part of the reaction product of the invention to the reactor for reaction after the gas part is purified by flash washing.
Preferably, the method further comprises the step of rectifying and separating the liquid part of the reaction product to obtain the product acetic acid, wherein the residual liquid is returned to the reactor for circulation to participate in the reaction after light and heavy components are removed.
The invention has the beneficial effects that:
Compared with the prior art for preparing acetic acid from methane and carbon dioxide, the invention has at least the following advantages:
1. The reaction of the invention does not need to add other high-cost raw materials such as acid, hydrogen, oxygen and the like, and the added water vapor is a low-cost clean raw material, so that the production cost can be further reduced and the safety can be improved.
2. The methyl iodide catalyst used in the invention is a cocatalyst used in the existing process for producing acetic acid by methanol carbonylation, but no one can apply the methyl iodide catalyst to the process for preparing acetic acid by reacting methane with carbon dioxide, the inventor team surprisingly finds that the combination of the methyl iodide catalyst and water can be directly used in the process for preparing acetic acid by reacting methane with carbon dioxide, and the research cost and the process adjustment cost of other catalysts can be saved.
3. By controlling the pressure and the temperature, all the reaction raw materials, the catalyst methyl iodide and the water can participate in the reaction in a liquid phase form, so that the reaction can be carried out in a liquid phase form of homogeneous catalysis reaction, and the method has more advantages in catalysis effect and reaction control compared with gas phase catalysis and/or heterogeneous catalysis reaction adopted in the prior art.
4. Because of the large difference in boiling points between the reaction feed and the catalyst methane, carbon dioxide, methyl iodide and product acetic acid, unreacted feed gas can be readily returned to the reactor for recycling (e.g., by flash evaporation) while product acetic acid is extracted in liquid form, e.g., by rectification.
5. The main reaction raw materials used in the invention can be respectively derived from natural gas and carbon dioxide generated by various industrial activities, and chemical raw materials do not need to be purchased specially, so that the carbon dioxide discharged by the enterprises or the partners of the enterprises can be utilized locally under the condition of carrying out the industrial activities, thereby changing waste into valuables and making positive contribution to global reduction of greenhouse effect.
6. The method for preparing acetic acid can efficiently convert raw materials, can convert about 60-70% of raw materials calculated by methane, has extremely high yield of the product acetic acid which can reach more than 90%, is far superior to the technology for preparing acetic acid by methane and carbon dioxide in the prior art, and has good industrial application prospect.
Detailed Description
The examples are presented for the purpose of better illustrating the invention and are not intended to limit the invention to the examples. Based on the above description, a person skilled in the art may make insubstantial modifications and adaptations to the following embodiments without departing from the spirit of the invention, and the scope of the invention is particularly pointed out in the claims.
The total reaction of the invention is CO 2 + CH4 CH3COOH
The process in which the catalyst methyl iodide and water vapor participate can be expressed as a two-step reaction of:
CO2 + H2O + CH3ICH3COOH + HI
HI + CH4 CH3I + H2O
Therefore, the invention can obtain the target product acetic acid through one-step reaction in one reactor, and can also obtain the target product acetic acid through two-step reaction in two reactors.
The raw material of the present invention may be commercially available high-purity carbon dioxide (at least 90% by mass), or carbon dioxide recovered from various industrial activities may be used as it is or after being processed into high-purity carbon dioxide. Similarly, methane may be commercially available high purity methane (at least 90% by mass), or methane contained in natural gas may be used as it is or after being processed into high purity methane. From the viewpoints of improving the reaction quality and reducing side reactions, a high-purity reaction raw material is preferably used.
For the reaction condition control of the present invention, the raw material amount, the reaction temperature and the pressure control are main control points, and generally, the main raw materials methane and carbon dioxide can be used in a photographic equivalent ratio, and the volume ratio of methane to carbon dioxide is preferably 0.5-2:1 so that both can sufficiently react. For methyl iodide and water vapor to act as a catalyst, it may be provided in a smaller proportion than the main raw materials, preferably with a volume ratio of carbon dioxide to water vapor of 3-6:1, and methyl iodide in an amount of 0.1-2% by weight of the total amount of the reaction raw materials, so long as the optimal catalytic effect can be achieved.
The reaction temperature and pressure of the present invention are usually required to be high temperature and high pressure to improve the conversion rate and yield, the reaction of the present invention can be performed under the condition of higher than normal pressure and can be performed under 40MPa at the highest, but the reaction pressure range of 2-8MPa is optimal to be used by combining the factors of conversion rate, yield and cost, etc.
The reaction of the present invention is usually carried out at high temperature and pressure to increase the conversion and yield, and the reaction of the present invention is usually carried out at a temperature higher than 100 ℃ and can be carried out at 220 ℃ at most, but the reaction temperature range of 170-210 ℃ is optimal by balancing the factors of conversion, yield and cost.
Regarding the separation and recovery of the products after the reaction, adjustments may be made with reference to the process for the production of acetic acid by the carbonylation of methanol, a process which is a process for the production of acetic acid that is particularly well established in the art. For example, by utilizing the principle that the boiling points of substances at high and low pressures are different, a mixture obtained by liquid phase reaction at high pressure is subjected to flash evaporation at low pressure to carry out gas-liquid separation, unreacted raw material gas is returned to a reactor for recycling, and acetic acid as a product is separated by rectification.
Example 1
The carbon dioxide and methane with the volume ratio of 5:5 are preheated to 100 ℃, and then are introduced into a zirconium alloy reactor loaded with methyl iodide together with water vapor (the volume ratio of the carbon dioxide to the water vapor is 5:1). The temperature of the reactor is controlled to be 200 ℃, the reaction pressure is 3MPa, and the synthesis reaction is carried out in a liquid phase form to generate acetic acid.
After the reaction is finished, the product at the outlet of the reactor is subjected to gas-liquid separation through a flash evaporator, the separated gas part is returned to the inlet of a compressor to be returned to the reactor for circulation to participate in the reaction, the separated liquid part is rectified to obtain the product acetic acid, and the residual liquid after rectification enters the inlet of a high-pressure liquid pump to be returned to the reactor for circulation to participate in the reaction.
The methane conversion after completion of the reaction and the acetic acid yield of the product were measured by conventional methods in the art, and the result showed that the methane conversion was 70% and the acetic acid yield was 95%.
Example 2
The carbon dioxide and methane with the volume ratio of 4.5:4.5 are preheated to 100 ℃, and then are introduced into a zirconium alloy reactor loaded with methyl iodide together with water vapor (the volume ratio of the carbon dioxide to the water vapor is 4.5:1). The temperature of the reactor is controlled to be 195 ℃, the reaction pressure is 3.2MPa, and the synthesis reaction is carried out in a liquid phase form to generate acetic acid.
After the reaction is finished, the product at the outlet of the reactor is subjected to gas-liquid separation through a flash evaporator, the separated gas part is returned to the inlet of a compressor to be returned to the reactor for circulation to participate in the reaction, the separated liquid part is rectified to obtain the product acetic acid, and the residual liquid after rectification enters the inlet of a high-pressure liquid pump to be returned to the reactor for circulation to participate in the reaction.
The methane conversion after completion of the reaction and the acetic acid yield of the product were measured by a conventional method in the art, and the result showed that the methane conversion was 68% and the acetic acid yield was 93%.
Example 3
The carbon dioxide and methane with the volume ratio of 5:5 are preheated to 100 ℃, and then are introduced into a zirconium alloy reactor loaded with methyl iodide together with water vapor (the volume ratio of the carbon dioxide to the water vapor is 5:1). The temperature of the reactor is controlled to be 196 ℃, the reaction pressure is 3.5MPa, and the synthesis reaction is carried out in a liquid phase form to generate acetic acid.
After the reaction is finished, the product at the outlet of the reactor is subjected to gas-liquid separation through a flash evaporator, the separated gas part is returned to the inlet of a compressor to be returned to the reactor for circulation to participate in the reaction, the separated liquid part is rectified to obtain the product acetic acid, and the residual liquid after rectification enters the inlet of a high-pressure liquid pump to be returned to the reactor for circulation to participate in the reaction.
The methane conversion after completion of the reaction and the acetic acid yield of the product were measured by a conventional method in the art, and the result showed that the methane conversion was 69% and the acetic acid yield was 94%.
Claims (8)
1. A method for preparing acetic acid by using natural gas and carbon dioxide is characterized in that methyl iodide and water vapor are used as catalysts, the carbon dioxide and the methane react in a reactor to generate a reaction product, the acetic acid is separated from the reaction product, the reaction pressure is 2-8MPa, and the reaction temperature is 170-210 ℃.
2. The method of claim 1, wherein the volume ratio of methane to carbon dioxide is 0.5-2:1.
3. The method according to claim 1 or 2, wherein the volume ratio of carbon dioxide to water vapor is 3-6:1.
4. The method of claim 3, wherein the methyl iodide is in the form of a flowing liquid.
5. The method of claim 4, further comprising returning a gaseous portion of the reaction product to the reactor for recycle to the reaction.
6. The method of claim 5, wherein the gas portion is scrubbed by flash evaporation prior to return.
7. The method according to claim 1, 2 and 4-6, further comprising separating acetic acid product from the liquid portion of the reaction product, wherein the remaining liquid is recycled to the reactor for reaction after light and heavy components are removed.
8. The method of claim 7, wherein the acetic acid product is separated by distillation.
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103402965A (en) * | 2012-02-08 | 2013-11-20 | 国际人造丝公司 | Production of acetic acid from methanol |
| CN106715379A (en) * | 2014-10-02 | 2017-05-24 | 国际人造丝公司 | Process for producing acetic acid |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| BR9911058A (en) * | 1998-05-15 | 2001-10-30 | Res Triangle Inst | Process for the preparation of alkylcarboxylic acids by carboxylation of lower methanes |
| CN1103330C (en) * | 2000-09-30 | 2003-03-19 | 太原理工大学 | Process for synthesizing acetic acid in heterogeneous catalysis system |
| US6596781B1 (en) * | 2002-05-02 | 2003-07-22 | Chevron U.S.A. Inc. | Integrated process for preparing Fischer-Tropsch products and acetic acid from synthesis gas |
| CN112939763B (en) * | 2019-12-10 | 2022-06-03 | 中国科学院大连化学物理研究所 | Method for preparing acetic acid from methyl halide |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103402965A (en) * | 2012-02-08 | 2013-11-20 | 国际人造丝公司 | Production of acetic acid from methanol |
| CN106715379A (en) * | 2014-10-02 | 2017-05-24 | 国际人造丝公司 | Process for producing acetic acid |
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