Method for recovering n-heptane in tail gas in ibuprofen synthesis process

Abstract

The invention relates to a recovery method for separating n-heptane in tail gas in an ibuprofen synthesis process by adopting double-tower extractive distillation. The process comprises the following components: a mixer (M1), an n-heptane removal tower (T1), an n-heptane removal tower condenser (CL1), an n-heptane storage tank (C1), an n-heptane removal tower reboiler (H1), a capture tower (T2), a capture tower condenser (CL2), an organic matter storage tank (C2), a capture tower reboiler (H2), a condenser (COL), a centrifugal pump (P1) and a centrifugal pump (P2). The method for removing the n-heptane in the industrial tail gas by the capturing process comprises the following steps: introducing the tail gas containing the n-heptane into an n-heptane removal tower (T1), introducing a capturing agent into a capturing tower, and capturing the n-heptane in the tower by the capturing agent. And after the n-heptane is completely captured, the obtained mixed solution enters a capturing tower (T2). Effective separation is carried out in the capture tower (T2), organic matter mixed liquid is extracted from the tower top, and capture liquid is extracted from the tower bottom. The obtained capturing liquid circularly enters the capturing tower, so that the recycling of the capturing agent is realized. The technical method for capturing the n-heptane in the ibuprofen synthesis process is economical and environment-friendly.

Description

[Technical field]

[0001] The invention belongs to the field of separation and purification in the pharmaceutical industry, and in particular relates to a method for recovering n-heptane in tail gas of an ibuprofen synthesis process by using double-tower extraction and distillation separation. [Background technology]

[0002] With the acceleration of industrialization and the rapid growth of the national economy, industrial production has caused great damage to the ecological environment on which human beings depend for survival. Air pollution is a major environmental problem currently facing the country, among which industrial emissions are one of the main sources of air pollutants. In industrial waste gas, organic waste gas enters the body through the respiratory tract and skin, etc., which will cause temporary and permanent damage to human respiratory, blood, liver and other systems and organs. Its components are mainly various hydrocarbons, alcohols and aldehydes. Therefore, studying an economical and effective treatment method is the key to solving the problem of dusty gas. Ibuprofen is a phenylpropionic acid non-steroidal anti-inflammatory drug with significant efficacy and few adverse reactions. Ibuprofen entered the market in the late 1970s and has developed rapidly around the world. However, in the production process of ibuprofen, a large amount of waste gas containing n-heptane will be generated. If it is directly discharged, it will inevitably pollute the air environment and cause waste of resources.

[0003] n-Heptane is an important chemical raw material. As an important basic raw material and fine chemical in the chemical industry, n-heptane can be used as an analytical reagent, a reference material for chromatographic analysis, a solvent, an extraction solvent for animal and plant oils and fats, a quick-drying rubber adhesive and a cleaning solvent.

[0004] A large amount of tail gas containing n-heptane will be produced in the production of ibuprofen. Among them, n-heptane, ethyl acetate and chloroform will form azeotropes at normal pressure, and the azeotropic points are 76.19°C (18.61wt% ethyl acetate, 81.39wt% n-heptane), 77.83°C (74.98wt% ethyl acetate, 25.02wt% chloroform) and 77.00°C (57.87wt% ethyl acetate, 16.07wt% n-heptane, 26.06wt% chloroform). The separation and recovery of n-heptane, ethyl acetate and chloroform in the tail gas of ibuprofen production can reduce production costs and further reduce emissions. Due to the presence of azeotropes in the mixture, effective separation cannot be achieved using a simple distillation method, so a special distillation method is required.

[0005] The invention utilizes the characteristic that the relative volatility of substances in the tail gas of the ibuprofen synthesis process containing n-heptane changes toward a direction of easier separation as a capture agent is added, recovers the n-heptane in the tail gas of the ibuprofen synthesis process, and can realize effective separation of the ternary azeotropic mixture through extractive distillation. [Summary of the invention]

[0006] [Technical issues to be solved]

[0007] The invention aims to provide a method for recovering tail gas from a Lofen synthesis process containing n-heptane by double-tower extractive distillation, so as to realize a process design for efficiently recovering an azeotropic mixture containing n-heptane by double-towers.

[0008] [Technical solution]

[0009] The invention provides a method for recovering tail gas from an ibuprofen synthesis process containing n-heptane by double-tower extractive distillation. The method utilizes the characteristic that the relative volatility of substances in the tail gas from the ibuprofen synthesis process containing n-heptane changes toward a direction that is easier to separate as a capture agent is added, and adopts a process flow of extractive distillation to realize the recovery of n-heptane in the tail gas from the ibuprofen synthesis process.

[0010] The present invention proposes a process for recovering tail gas containing n-heptane in the ibuprofen synthesis process by double-tower extraction and distillation, and provides a continuous capture process route for stably removing tail gas containing n-heptane in the ibuprofen synthesis process. Tail gas containing n-heptane enters a capture tower, and a capture agent in the tower captures n-heptane, a capture liquid is formed at the bottom of the tower, and an n-heptane product is generated at the top of the tower. The capture liquid is discharged from the capture tower and enters the next separation unit. Organic matter and the capture agent are separated in the separation unit. The separated capture agent is used for recycling. The capture rate of n-heptane in the capture unit of the present invention is as high as 90%. The present invention screens out several commonly used capture agents, and experiments on capturing n-heptane tail gas are carried out respectively. The capture efficiency of the capture agent for n-heptane is as high as more than 90%. The air pollution caused by the emission of n-heptane tail gas is reduced while saving effective resources. A win-win situation of environmental benefits and economic benefits is achieved.

[0011] The invention screens out several applicable high-efficiency capture agents, and provides a method for capturing n-heptane in industrial tail gas which has simple process and is easy to implement.

[0012] The present invention is realized by the following technical scheme: a process for capturing and removing n-heptane from industrial tail gas, characterized in that the device comprises the following components: a mixer (M1), a n-heptane removal tower (T1), a n-heptane removal tower condenser (CL1), an n-heptane storage tank (C1), a n-heptane removal tower reboiler (H1), a capture tower (T2), a capture tower condenser (CL2), an organic matter storage tank (C2), a capture tower reboiler (H2), a condenser (COL), a centrifugal pump (P1), and a centrifugal pump (P2). The present invention is characterized in that the method comprises the following steps:

[0013] (1) passing the tail gas containing n-heptane into a de-n-heptane tower (T1) and obtaining an n-heptane product after distillation;

[0014] (2) passing the organic matter containing the capture agent into the capture tower (T2);

[0015] (3) The organic matter containing the capture agent is passed into a capture tower, and the capture agent and organic matter solution are obtained at the bottom and top of the tower respectively;

[0016] (4) The mixed solution containing organic matter and capture liquid is pumped into the capture tower (T2) through a centrifugal pump (P1), and effectively separated in the tower. The organic matter is extracted from the top of the tower and the capture liquid is extracted from the bottom of the tower. The obtained capture liquid is circulated into the capture tower to achieve the recycling of the capture agent.

[0017] According to another preferred embodiment of the present invention, it is characterized in that the de-n-heptane tower (T1) and the capture tower (T2) are atmospheric pressure towers, and the tower top pressure is maintained at 2 kPa.

[0018] According to another preferred embodiment of the present invention, it is characterized in that: the n-heptane feed temperature is 40-70°C, the exhaust gas treatment capacity is 200-3000m 3 / h, the mass percentage of n-heptane in the exhaust gas is 10%-30%, the maximum designed flow rate of the capture agent is 500-1500kg / h, the effective height of the de-n-heptane tower (T1) for treating the tail gas containing n-heptane is 5-12m; the effective height of the capture tower (T2) is 8-16m.

[0019] According to another preferred embodiment of the present invention, it is characterized in that the temperature inside the de-n-heptane tower (T1) is 0-120°C, and the temperature inside the capture tower (T2) is 0-300°C.

[0020] According to another preferred embodiment of the present invention, it is characterized in that: the method is used to capture n-heptane in the tail gas, and the n-heptane capture rate reaches more than 88%.

[0021] The n-heptane-containing tail gas removal technology of the present invention is specifically described as follows:

[0022] At room temperature, the tail gas containing n-heptane is passed into a de-n-heptane tower (T1), and a capture agent is introduced to extract and distill the n-heptane tail gas. The material is fed from the bottom of the tower, and the feed temperature is 40-70°C. The analytical pure capture agent is passed into the de-n-heptane tower (T1). The capture agent captures n-heptane in a spraying manner. In the de-n-heptane tower (T1), the n-heptane gas runs upward, and the capture agent and the organic mixed liquid run downward. When the mixed solution formed after the capture agent contacts the organic mixed liquid and flows to the bottom of the tower, multi-stage mass transfer is carried out. After the n-heptane is completely captured, the mixed liquid obtained enters the capture tower (T2). Effective separation is carried out in the capture tower (T2), the organic mixed liquid is extracted from the top of the tower, and the capture liquid is extracted from the bottom of the tower. The obtained capture liquid is circulated into the capture tower to realize the recycling of the capture agent.

[0023] [Beneficial Effects]

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention improves the removal effect of n-heptane in the ibuprofen synthesis process. The invention can achieve efficient removal of n-heptane, and the capture rate of n-heptane after treatment by the present invention is as high as more than 88%.

[0026] (2) The method has the advantages of simple process, high purity of n-heptane after separation, easy recovery of the extractant, good chemical and thermal stability, and green and pollution-free.

[0027] (3) The present invention avoids air pollution caused by tail gas containing n-heptane; the obtained n-heptane can be recycled and reused, which can reduce the waste of effective resources and avoid pollution to the environment.

Brief Description of the Drawings

[0028] Attached Figure 1 The process flow chart of the present invention for recovering n-heptane from the tail gas of the ibuprofen synthesis process by extractive distillation separation is as follows:

[0029] In the figure: mixer (M1), de-n-heptane tower (T1), de-n-heptane tower condenser (CL1), n-heptane storage tank (C1), de-n-heptane tower reboiler (H1), capture tower (T2), capture tower condenser (CL2), organic matter storage tank (C2), capture tower reboiler (H2), condenser (COL), centrifugal pump (P1), centrifugal pump (P2). [Specific implementation method]

[0030] The following is further described in conjunction with the accompanying drawings, which does not limit the scope of the present invention.

[0031] Embodiment 1:

[0032] Take 50g of n-heptane solution and pass it into the de-n-heptane tower (T1). The effective height of the de-n-heptane tower (T1) is 9m, and the pressure at the top of the tower is maintained at 2kPa. 150g of the capture liquid-dimethyl sulfoxide is sprayed down from the top of the tower, and the n-heptane is removed in the de-n-heptane tower (T1). The feed temperature is 50°C. After a period of capture, the n-heptane product and the organic mixed liquid containing the capture agent are formed at the top and bottom of the tower respectively. The mixed liquid is pumped into the capture tower (T2), and the organic matter-capture agent is efficiently separated in the capture tower (T2). The effective height of the capture tower (T2) is 10m, and the pressure at the top of the tower is maintained at 2kPa. The recovery rate of the capture agent after separation is 80%.

[0033] Embodiment 2:

[0034] Take 80g of n-heptane solution and pass it into the de-n-heptane tower (T1). The effective height of the de-n-heptane tower (T1) is 10m, and the pressure at the top of the tower is maintained at 2kPa. 200g of the capture liquid-dimethylacetamide is sprayed down from the top of the tower, and the n-heptane is removed in the de-n-heptane tower (T1). The feed temperature is 55°C. After a period of capture, the n-heptane product and the organic mixed liquid containing the capture agent are formed at the top and bottom of the tower respectively. The mixed liquid is pumped into the capture tower (T2), and the organic matter-capture agent is efficiently separated in the capture tower (T2). The effective height of the capture tower (T2) is 12m, and the pressure at the top of the tower is maintained at 2kPa. The recovery rate of the capture agent after separation is 83%.

[0035] Embodiment 3:

[0036] Take 70g of n-heptane solution and pass it into the de-n-heptane tower (T1). The effective height of the de-n-heptane tower (T1) is 11m, and the pressure at the top of the tower is maintained at 2kPa. 180g of the capture liquid - N,N-dimethylformamide is sprayed down from the top of the tower, and the n-heptane is removed in the de-n-heptane tower (T1). The feed temperature is 60°C. After a period of capture, the n-heptane product and the organic mixed liquid containing the capture agent are formed at the top and bottom of the tower respectively. The mixed liquid is pumped into the capture tower (T2), and the organic matter-capture agent is efficiently separated in the capture tower (T2). The effective height of the capture tower (T2) is 15m, and the pressure at the top of the tower is maintained at 2kPa. The recovery rate of the capture agent after separation is 90%.

Claims

1. A method for recovering n-heptane from tail gas in an ibuprofen synthesis process, characterized in that The method uses a device consisting of the following parts: a mixer (M1), a de-n-heptane tower (T1), a de-n-heptane tower condenser (CL1), an n-heptane storage tank (C1), a de-n-heptane tower reboiler (H1), a capture tower (T2), a capture tower condenser (CL2), an organic matter storage tank (C2), a capture tower reboiler (H2), a condenser (COL), a centrifugal pump (P1), and a centrifugal pump (P2); wherein the bottom material flow of the de-n-heptane tower (T1) enters the capture tower (T2), and the high-purity product n-heptane is extracted from the top material flow of the de-n-heptane tower (T1); the high-purity extractant extracted from the bottom of the capture tower (T2) enters the condenser (COL) through the centrifugal pump (P2), is cooled, and then the extractant is supplemented and then refluxed to the de-n-heptane tower (T1); the recovery of n-heptane is completed; The above process is used to carry out a method for recovering n-heptane in the tail gas of an ibuprofen synthesis process, comprising the following steps: (1) passing the tail gas containing n-heptane into a de-n-heptane tower (T1) and obtaining an n-heptane product after distillation; (2) passing the organic matter containing the capture agent into the capture tower (T2); (3) The organic matter containing the capture agent is passed into a capture tower, and the capture agent and organic matter solution are obtained at the bottom and top of the tower respectively; (4) The mixed solution containing organic matter and capture liquid is pumped into the capture tower (T2) through a centrifugal pump (P1), and effectively separated in the tower, with the organic matter extracted from the top of the tower and the capture liquid extracted from the bottom of the tower. The obtained capture liquid is circulated into the capture tower to achieve the recycling of the capture agent; the capture agent in this method is one of dimethyl sulfoxide, dimethylacetamide, and N,N-dimethylformamide.

2. The method according to claim 1, characterized in that: The feed temperature of the tail gas containing n-heptane is 40-70° C., and the mass percentage of n-heptane in the tail gas is 10%-30%.

3. The method according to claim 1, characterized in that: The effective height of the de-n-heptane tower (T1) for treating the tail gas containing n-heptane is 5-12m; the effective height of the capture tower (T2) is 8-16m.

4. The method according to claim 1, characterized in that: The temperature inside the de-n-heptane tower (T1) is 0-120°C, and the temperature inside the capture tower (T2) is 0-300°C.

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