A method of treating organic alcohol plant purge gas

Abstract

The application discloses a treatment method of organic alcohol device purge gas, and belongs to the technical field of resource recycling, in particular to a method of mixing the purge gas from an organic alcohol hydrogenation unit and a carbonyl synthesis unit, reacting in a reactor to generate alcohol water crude products and low-concentration purge gas, preliminarily separating the alcohol water crude products by using an alcohol water separation membrane, sending the low-concentration purge gas to a waste gas combustion system for heat energy recovery, taking Pebax as a base material of the separation membrane, and dispersing granular porous activated carbon and / or hollow short fibers in the base material, wherein the porous activated carbon is made of corn straw powder through pretreatment and carbonization treatment, and the hollow short fibers are made by a dry jet-wet spinning method through a spinning casting solution containing polyacrylic acid and a core solution. The prepared separation membrane has good mechanical properties and tensile properties of 10-35 MPa, and has good separation performance with a separation factor of 400-1400.

Description

Technical Field

[0001] This invention belongs to the field of resource recycling technology, specifically relating to a method for treating purge gas from an organic alcohol device. Background Technology

[0002] The organic alcohol plant is divided into two units: carbonyl synthesis and hydrogenation. Both units produce a certain amount of off-gas due to reaction conversion rates. The main off-gas components of the carbonyl synthesis unit are ethylene, hydrogen, and carbon monoxide. The main off-gas components of the hydrogenation unit are hydrogen and methane. Over 90% of these gases are active reaction components. While burning these off-gas in a boiler to produce steam can recover some heat, its recovery value is extremely low. To improve the utilization of off-gas and reduce resource waste, this invention aims to provide a method for the effective utilization of off-gas from an organic alcohol plant, further developing and utilizing the waste gas. Summary of the Invention

[0003] The purpose of this invention is to provide a method for treating the reaction gas of an organic alcohol apparatus that allows for the reuse of purge gas and provides a good separation effect on the prepared alcohol-water solution.

[0004] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0005] A method for treating purge gas from an organic alcohol unit includes: mixing purge gas from an organic alcohol hydrogenation unit and a carbonyl synthesis unit, reacting the mixture in a reactor to produce a crude alcohol-water product and a low-concentration purge gas; preliminarily separating the alcohol-water product by a separation membrane, and sending the low-concentration purge gas to an exhaust gas combustion system for heat recovery.

[0006] The separation membrane uses Pebax as the substrate, in which granular porous activated carbon and / or hollow short fibers are dispersed. The porous activated carbon is made from corn stalk powder through pretreatment and carbonization. The hollow short fibers are made from a spinning casting solution containing polyacrylic acid and a core solution through a dry-jet-wet spinning method. This invention uses Pebax as the substrate of the separation membrane, and then uses porous activated carbon and / or hollow short fibers as fillers. The fillers are dispersed within the Pebax membrane material. The interaction between the fillers and Pebax reduces the activity of the polymer matrix chain segments. Furthermore, the permeability of the fillers themselves and their dispersion within Pebax create micropores in the separation membrane, thereby increasing the permeation flux and achieving good separation of the target solution. However, the addition of fillers can lead to a decrease in the mechanical properties of the separation membrane.

[0007] Preferably, the main offgas composition of the carbonyl synthesis unit is ethylene, hydrogen, and carbon monoxide.

[0008] Preferably, the main offgas from the hydrogenation unit is hydrogen or methane.

[0009] A separation membrane includes: a Pebax substrate in which particulate porous activated carbon and / or hollow short fibers are dispersed; the porous activated carbon is made from corn stalk powder through pretreatment and carbonization; the hollow short fibers are made from a spinning casting solution containing polyacrylic acid and a core solution by a dry-jet-wet spinning method.

[0010] Preferably, the separation membrane is divided into three layers: upper, middle and lower. The main material of the middle layer is hollow short fiber, and the middle layer does not contain Pebax.

[0011] Preferably, the separation membrane contains a cross-linked structure of polyethyleneimine, which is formed by the combination of polyethyleneimine with carboxyl groups on porous activated carbon and / or hollow short fibers.

[0012] This invention discloses a method for preparing a separation membrane, comprising: adding filler to a solution containing Pebax, stirring and dispersing to prepare a casting solution, and then forming a separation membrane; the filler is granular porous activated carbon and / or hollow short fibers, wherein the porous activated carbon is prepared by pretreatment and carbonization of corn stalk powder; and the hollow short fibers are prepared by a spinning casting solution containing polyacrylic acid and a core solution through a dry-jet-wet spinning method.

[0013] Preferably, the filler is added to a solution containing Pebax, stirred and dispersed to form a casting solution, and a base layer is obtained by casting a membrane; a layer of hollow short fibers is laid flat on the base layer, and then a solution containing or not containing polyethyleneimine is added, and dried to form an intermediate layer; a casting solution containing or not containing polyethyleneimine is added to the intermediate layer, and dried to form a surface layer, thus obtaining a separation membrane. The filler was added to a Pebax solution, and a base membrane was prepared through a series of processes. A layer of hollow short fibers was added in the middle, followed by a casting solution to prepare the surface layer. The filler surface contains carboxyl groups. When the filler was used but polyethyleneimine was not, the middle layer was covered by the base layer and the surface layer. The surface layer was connected to the base layer through the voids in the middle layer during preparation, resulting in improved mechanical properties of the separation membrane. Compared to a single-layer separation membrane, the permeate flux decreased, but the separation effect on the target solution was greatly improved, indicating that the performance of the separation membrane was improved after the membrane was prepared with a three-layer structure. After introducing hollow short fibers in the preparation of the middle layer, polyethyleneimine was introduced, and then the third layer was prepared. The polyethyleneimine combined with the carboxylic acid structure in the three-layer structure of the membrane to form a composite structure, which improved the homogeneity of the separation membrane and further improved the separation effect on the target solution.

[0014] Preferably, the amount of filler used is 20-60 wt% of Pebax.

[0015] Preferably, in the preparation of the interlayer membrane, the amount of polyethyleneimine used is 20-50 wt% of the hollow short fibers.

[0016] Preferably, in the preparation of granular porous activated carbon, corn stalks are crushed and dried, added to a pretreatment solution and stirred for 2-5 hours, filtered, washed with distilled water, dried, heat-treated at 200-300℃ for 3-9 hours, and then carbonized at 700-900℃ for 1-4 hours to obtain granular porous activated carbon.

[0017] More preferably, in the preparation of granular porous activated carbon, the pretreatment solution is obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water, and the pretreatment solution contains 2-6 wt% sodium hydroxide and 1-4 wt% sodium bicarbonate.

[0018] More preferably, in the preparation of granular porous activated carbon, the amount of corn straw powder used is 3-12 wt% of the pretreatment solution.

[0019] Preferably, in the preparation of hollow short fibers, polyacrylic acid, glycerol, THF and NMP are mixed to obtain a spinning casting solution, which is degassed before spinning; a mixture of isopropanol and distilled water is used as the core liquid, and the spinning casting solution and the core liquid are pumped into the spinneret and extruded into water by a dry-jet-wet spinning method. The solvent in the membrane is mutually soluble and exchanged with the water to complete the phase transformation, and the membrane is collected to obtain a hollow fiber membrane. The hollow fiber membrane is then broken to produce hollow short fibers.

[0020] More preferably, in the preparation of hollow short fibers, the amount of polyacrylic acid used in the spinning casting solution is 40-50 wt% of NMP.

[0021] More preferably, in the preparation of hollow short fibers, the amount of glycerol used is 25-35 wt% of NMP.

[0022] More preferably, in the preparation of hollow short fibers, the amount of THF used is 25-35 wt% of NMP.

[0023] More preferably, in the preparation of hollow short fibers, isopropanol and distilled water in the core liquid are mixed at a mass ratio of 1:5-10.

[0024] Preferably, in the preparation of the separation membrane, Pebax is added to an ethanol solution and refluxed at 80-90°C for 0.5-3 hours. Then, filler is added at 20-40°C, ultrasonically dispersed, and stirred for 1-4 hours to obtain a casting solution. The casting solution is poured into a mold and dried at 50-70°C to obtain the separation membrane.

[0025] More preferably, in the preparation of the separation membrane, the ethanol solution contains 60-80 wt% ethanol.

[0026] More preferably, in the preparation of the separation membrane, the amount of Pebax used is 2-6 wt% of the ethanol solution.

[0027] More preferably, in the preparation of the separation membrane, the filler is granular porous activated carbon and / or hollow short fibers.

[0028] More preferably, in the preparation of the separation membrane, the amount of granular porous activated carbon added is 10-30 wt% of Pebax.

[0029] More preferably, in the preparation of the separation membrane, the amount of hollow short fibers added is 10-30 wt% of Pebax.

[0030] Preferably, in the preparation of the separation membrane, Pebax is added to an ethanol solution and refluxed at 80-90°C for 0.5-3 hours. Then, filler is added at 20-40°C, ultrasonically dispersed, and stirred for 1-4 hours to obtain a casting solution. The casting solution is poured into a mold and dried at 50-70°C to form a substrate layer. A layer of hollow short fibers is laid flat on the membrane of the substrate layer, and a polyethyleneimine solution is added and dried at 50-70°C to form an intermediate layer. Then, a casting solution containing polyethyleneimine is added and dried at 50-70°C. After drying, the membrane is treated at 100-120°C for 1-5 hours to form a surface layer, thus obtaining the separation membrane.

[0031] More preferably, in the preparation of the substrate layer of the separation membrane, the ethanol solution contains 60-80 wt% ethanol.

[0032] More preferably, in the preparation of the substrate layer of the separation membrane, the amount of Pebax used is 2-6 wt% of the ethanol solution.

[0033] More preferably, in the preparation of the substrate layer of the separation membrane, the filler is granular porous activated carbon and / or hollow short fibers.

[0034] More preferably, in the preparation of the substrate layer of the separation membrane, the amount of granular porous activated carbon added is 10-30 wt% of Pebax.

[0035] More preferably, in the preparation of the substrate layer of the separation membrane, the amount of hollow short fibers added is 10-30 wt% of Pebax.

[0036] More preferably, in the preparation of the intermediate layer of the separation membrane, the polyethyleneimine solution is prepared by adding polyethyleneimine to a mixture of isopropanol and distilled water, wherein the isopropanol and distilled water are mixed in a mass ratio of 1:0.2-5.

[0037] More preferably, in the preparation of the intermediate layer of the separation membrane, the polyethyleneimine solution used contains 20-50 wt% of hollow short fibers.

[0038] More preferably, isocyclohexanediol imide can be added during the preparation of the intermediate layer of the separation membrane, and the amount of isocyclohexanediol imide used in the preparation of the intermediate layer is 2-8 wt% of the hollow short fibers. In the preparation of the separation membrane, after adding hollow short fibers to the intermediate layer, isocyclohexanediol imide can be added or isocyclohexanediol imide can be used together with polyethyleneimine to prepare a separation membrane with better separation performance and better mechanical properties.

[0039] More preferably, in the preparation of the surface layer of the separation membrane, the amount of casting solution used in the preparation of the surface layer is the same as the amount of casting solution used in the preparation of the matrix layer, and the casting solution used in the preparation of the surface layer contains 1-4 wt% polyethyleneimine.

[0040] This invention utilizes a separation membrane made from a spinning casting solution containing polyacrylic acid and a core solution, spun into hollow short fibers via a dry-jet-wet spinning method. Porous activated carbon is prepared from pretreated and carbonized corn stalk powder. Pebax is used as the substrate, and the membrane contains dispersed granular porous activated carbon and / or hollow short fibers. Polyethyleneimine is further used in the preparation of the separation membrane, forming a cross-linked structure with the carboxyl groups of the porous activated carbon and / or hollow short fibers. Therefore, this invention offers the following advantages: the resulting separation membrane exhibits good mechanical properties, with a tensile strength of 10-35 MPa; and high permeation flux, ranging from 0.9-2 kg·m³. -2 h -1 The separation membrane exhibits good separation performance, with a separation factor of 400-1400. Therefore, this invention provides a method for treating the reaction gas from an organic alcohol apparatus that allows for the reuse of purge gas and provides good separation of the resulting alcohol-water solution. Attached Figure Description

[0041] Figure 1 Flowchart of the method for treating the offgassing reaction of organic alcohols;

[0042] Figure 2 Electron micrograph of the separation membrane;

[0043] Figure 3 The tensile strength diagram of the separation membrane;

[0044] Figure 4 This is a permeation flux diagram of the separation membrane;

[0045] Figure 5 This is a diagram of the separation factor of the separation membrane. Detailed Implementation

[0046] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings:

[0047] Example 1:

[0048] A method for preparing a separation membrane,

[0049] Preparation of hollow short fibers: Polyacrylic acid, glycerol, THF, and NMP were mixed to obtain a spinning casting solution, which was degassed before spinning. A mixture of isopropanol and distilled water was used as the core solution. The spinning casting solution and the core solution were pumped into a spinneret and extruded into water using a dry-jet-wet spinning method. The solvent in the membrane and water exchanged to complete the phase inversion, and the membrane was collected to obtain a hollow fiber membrane. The hollow fiber membrane was then broken into hollow short fibers. In the spinning casting solution, the amount of polyacrylic acid used was 50 wt% of NMP, the amount of glycerol used was 30 wt% of NMP, and the amount of THF used was 30 wt% of NMP. Isopropanol and distilled water were mixed in the core solution at a mass ratio of 1:10.

[0050] Preparation of the separation membrane: Pebax was added to an ethanol solution and refluxed at 90°C for 1 hour. Then, filler was added at 30°C, ultrasonically dispersed, and stirred for 2 hours to obtain a casting solution. The casting solution was poured into a mold and dried at 60°C to obtain the separation membrane. The ethanol solution contained 70 wt% ethanol, and the amount of Pebax used was 4 wt% of the ethanol solution. The filler was hollow short fiber, and the amount of hollow short fiber added was 20 wt% of Pebax.

[0051] Example 2:

[0052] A method for preparing a separation membrane,

[0053] The difference between this embodiment and Example 1 is that the filler used in the preparation of the separation membrane is granular porous activated carbon, and the amount of granular porous activated carbon added is 20 wt% of Pebax.

[0054] Preparation of granular porous activated carbon: Corn stalks were crushed and dried, added to a pretreatment solution and stirred for 3 hours. After filtration, the carbon was washed with distilled water, dried, heat-treated at 300℃ for 5 hours, and then carbonized at 800℃ for 3 hours to obtain granular porous activated carbon. The pretreatment solution was obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water. The pretreatment solution contained 4 wt% sodium hydroxide and 2 wt% sodium bicarbonate. The amount of corn stalk powder used was 6 wt% of the pretreatment solution.

[0055] Example 3:

[0056] A method for preparing a separation membrane,

[0057] The difference between this embodiment and Example 1 is that the filler used in the preparation of the separation membrane is granular porous activated carbon and hollow short fibers. The amount of granular porous activated carbon added is 20 wt% of Pebax, and the amount of hollow short fibers added is 20 wt% of Pebax.

[0058] Preparation of granular porous activated carbon: Corn stalks were crushed and dried, added to a pretreatment solution and stirred for 3 hours. After filtration, the carbon was washed with distilled water, dried, heat-treated at 300℃ for 5 hours, and then carbonized at 800℃ for 3 hours to obtain granular porous activated carbon. The pretreatment solution was obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water. The pretreatment solution contained 4 wt% sodium hydroxide and 2 wt% sodium bicarbonate. The amount of corn stalk powder used was 6 wt% of the pretreatment solution.

[0059] Example 4:

[0060] A method for preparing a separation membrane,

[0061] The difference between this embodiment and Example 1 lies in the preparation of the separation membrane.

[0062] Preparation of the separation membrane: Pebax was added to an ethanol solution and refluxed at 90°C for 1 hour. Then, filler was added at 30°C, ultrasonically dispersed, and stirred for 2 hours to obtain a casting solution. The casting solution was poured into a mold and dried at 60°C to form a substrate layer. A layer of hollow short fibers was laid on the substrate layer membrane, and a polyethyleneimine solution was added and dried at 60°C to form an intermediate layer. Then, a casting solution containing polyethyleneimine was added and dried at 60°C. After drying, the membrane was treated at 110°C for 3 hours to form a surface layer, thus obtaining the separation membrane. The ethanol solution contains 70 wt% ethanol, and the amount of Pebax used is 4 wt% of the ethanol solution. The filler is hollow short fiber, and the amount of hollow short fiber added is 20 wt% of Pebax. The polyethyleneimine solution is prepared by adding polyethyleneimine to a mixture of isopropanol and distilled water. The isopropanol and distilled water are mixed in a mass ratio of 1:2. In the use of the polyethyleneimine solution, the amount of polyethyleneimine is 40 wt% of the hollow short fiber. The amount of casting solution used in the preparation of the surface layer is the same as that used in the preparation of the matrix layer. The casting solution used in the preparation of the surface layer contains 3 wt% polyethyleneimine.

[0063] Example 5:

[0064] A method for preparing a separation membrane,

[0065] The difference between this embodiment and embodiment 4 is that the filler used in the preparation of the separation membrane is granular porous activated carbon, and the amount of granular porous activated carbon added is 20 wt% of Pebax.

[0066] Preparation of granular porous activated carbon: Corn stalks were crushed and dried, added to a pretreatment solution and stirred for 3 hours. After filtration, the carbon was washed with distilled water, dried, heat-treated at 300℃ for 5 hours, and then carbonized at 800℃ for 3 hours to obtain granular porous activated carbon. The pretreatment solution was obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water. The pretreatment solution contained 4 wt% sodium hydroxide and 2 wt% sodium bicarbonate. The amount of corn stalk powder used was 6 wt% of the pretreatment solution.

[0067] Example 6:

[0068] A method for preparing a separation membrane,

[0069] The difference between this embodiment and embodiment 4 is that the filler used in the preparation of the separation membrane is granular porous activated carbon and hollow short fibers. The amount of granular porous activated carbon added is 20 wt% of Pebax, and the amount of hollow short fibers added is 20 wt% of Pebax.

[0070] Preparation of granular porous activated carbon: Corn stalks were crushed and dried, added to a pretreatment solution and stirred for 3 hours. After filtration, the carbon was washed with distilled water, dried, heat-treated at 300℃ for 5 hours, and then carbonized at 800℃ for 3 hours to obtain granular porous activated carbon. The pretreatment solution was obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water. The pretreatment solution contained 4 wt% sodium hydroxide and 2 wt% sodium bicarbonate. The amount of corn stalk powder used was 6 wt% of the pretreatment solution.

[0071] Example 7:

[0072] A method for preparing a separation membrane,

[0073] The difference between this embodiment and Example 4 lies in the preparation of the separation membrane.

[0074] Preparation of the separation membrane: Pebax was added to an ethanol solution and refluxed at 90°C for 1 hour. Then, filler was added at 30°C, ultrasonically dispersed, and stirred for 2 hours to obtain a casting solution. The casting solution was poured into a mold and dried at 60°C to form a substrate layer. A layer of hollow short fibers was laid flat on the substrate layer membrane and treated at 60°C to form an intermediate layer. Then, casting solution was added again, dried at 60°C, and treated at 110°C for 3 hours to form a surface layer, thus obtaining the separation membrane. The ethanol solution contained 70 wt% ethanol, and the amount of Pebax used was 4 wt% of the ethanol solution. The filler was hollow short fibers, and the amount of hollow short fibers added was 20 wt% of Pebax. The amount of casting solution used in the surface layer preparation was the same as that used in the substrate layer preparation.

[0075] Example 8:

[0076] A method for preparing a separation membrane,

[0077] The difference between this embodiment and Example 4 lies in the preparation of the separation membrane.

[0078] Preparation of the separation membrane: Pebax was added to an ethanol solution and refluxed at 90°C for 1 hour. Then, filler was added at 30°C, ultrasonically dispersed, and stirred for 2 hours to obtain a casting solution. The casting solution was poured into a mold and dried at 60°C to form a substrate layer. A layer of hollow short fibers was laid on the substrate layer membrane, and a polyethyleneimine solution was added and dried at 60°C to form an intermediate layer. Then, a casting solution containing polyethyleneimine was added and dried at 60°C. After drying, the membrane was treated at 110°C for 3 hours to form a surface layer, thus obtaining the separation membrane. The ethanol solution contains 70 wt% ethanol, and the amount of Pebax used is 4 wt% of the ethanol solution. The filler is hollow short fiber, and the amount of hollow short fiber added is 20 wt% of Pebax. The polyethyleneimine solution is prepared by adding polyethyleneimine and isocyclohexylimide to a mixture of isopropanol and distilled water. The isopropanol and distilled water are mixed in a mass ratio of 1:2. The amount of isocyclohexylimide used in the polyethyleneimine solution is 5 wt% of the hollow short fiber, and the amount of polyethyleneimine used in the polyethyleneimine solution is 40 wt% of the hollow short fiber. The amount of casting solution used in the surface layer preparation is the same as the amount of casting solution used in the matrix layer preparation. The casting solution used in the surface layer preparation contains 3 wt% polyethyleneimine.

[0079] Example 9:

[0080] A method for preparing a separation membrane,

[0081] The difference between this embodiment and Example 8 is that the filler used in the preparation of the separation membrane is granular porous activated carbon, and the amount of granular porous activated carbon added is 20 wt% of Pebax.

[0082] Preparation of granular porous activated carbon: Corn stalks were crushed and dried, added to a pretreatment solution and stirred for 3 hours. After filtration, the carbon was washed with distilled water, dried, heat-treated at 300℃ for 5 hours, and then carbonized at 800℃ for 3 hours to obtain granular porous activated carbon. The pretreatment solution was obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water. The pretreatment solution contained 4 wt% sodium hydroxide and 2 wt% sodium bicarbonate. The amount of corn stalk powder used was 6 wt% of the pretreatment solution.

[0083] Example 10:

[0084] A method for preparing a separation membrane,

[0085] The difference between this embodiment and embodiment 8 is that the filler used in the preparation of the separation membrane is granular porous activated carbon and hollow short fibers. The amount of granular porous activated carbon added is 20 wt% of Pebax, and the amount of hollow short fibers added is 20 wt% of Pebax.

[0086] Preparation of granular porous activated carbon: Corn stalks were crushed and dried, added to a pretreatment solution and stirred for 3 hours. After filtration, the carbon was washed with distilled water, dried, heat-treated at 300℃ for 5 hours, and then carbonized at 800℃ for 3 hours to obtain granular porous activated carbon. The pretreatment solution was obtained by dissolving sodium hydroxide and sodium bicarbonate in distilled water. The pretreatment solution contained 4 wt% sodium hydroxide and 2 wt% sodium bicarbonate. The amount of corn stalk powder used was 6 wt% of the pretreatment solution.

[0087] Example 11:

[0088] A method for preparing a separation membrane,

[0089] The difference between this embodiment and Example 8 lies in the preparation of the separation membrane.

[0090] Preparation of the separation membrane: Pebax was added to an ethanol solution and refluxed at 90°C for 1 hour. Then, filler was added at 30°C, ultrasonically dispersed, and stirred for 2 hours to obtain a casting solution. The casting solution was poured into a mold and dried at 60°C to form a substrate layer. A layer of hollow short fibers was laid on the substrate layer membrane, and isocyclohexylimide solution was added and dried at 60°C to form an intermediate layer. Then, a casting solution containing polyethyleneimine was added and dried at 60°C. After drying, the membrane was treated at 110°C for 3 hours to form a surface layer, thus obtaining the separation membrane. The ethanol solution contains 70 wt% ethanol, and the amount of Pebax used is 4 wt% of the ethanol solution. The filler is hollow short fiber, and the amount of hollow short fiber added is 20 wt% of Pebax. The isocyclohexylimide solution is prepared by adding isocyclohexylimide to a mixture of isopropanol and distilled water. The isopropanol and distilled water are mixed in a mass ratio of 1:2. The amount of isocyclohexylimide used in the isocyclohexylimide solution is 5 wt% of the hollow short fiber. The amount of casting solution used in the preparation of the surface layer is the same as the amount of casting solution used in the preparation of the matrix layer.

[0091] Example 12:

[0092] A method for treating the reaction of purge gas from an organic alcohol apparatus.

[0093] The organic alcohol unit is divided into two units: carbonyl synthesis and hydrogenation. Both units produce a certain amount of purge gas due to reaction conversion rates. The purge gas from the carbonyl synthesis unit mainly consists of ethylene, hydrogen, and carbon monoxide. The purge gas from the hydrogenation unit mainly consists of hydrogen and methane. Over 90% of these gases are active reaction components. If these purge gases are used to burn in a boiler to produce steam, although some heat can be recovered, its recovery value is extremely low.

[0094] The purge gas from the organic alcohol hydrogenation unit and the carbonyl synthesis unit is mixed by proportioning adjustment (V101), then heated to the reaction temperature by the preheater (E101), and then enters the purge gas treatment reaction device (R101A / B). This reaction device can be operated in multiple stages in series according to the purge gas volume and reaction effect. After the gas passes through the reaction device, it is condensed by the condenser (E102) and then enters the separator for gas-liquid separation. The crude product and the gas with a lower concentration of effective composition are then sent to the waste gas combustion system for heat recovery.

[0095] The reaction flow of the purge gas treatment method for organic alcohol units is as follows: Figure 1 As shown, A1 is the purge gas from the hydrogenation unit, A2 is the purge gas from the carbonyl synthesis unit, B1 represents the gas going to the combustion system, B2 represents the crude product, V101 is the mixing tank, E101 is the preheater, R101A is the first purge gas reaction device, R101B is the second purge gas reaction device, E102 is the condenser, and V102 is the separation tank. After gas-liquid separation in the separation tank, the crude product undergoes preliminary separation via a separation membrane. If higher purity is required, it is sent to the distillation system for further purification. In this embodiment, the separation membrane can be any of the separation membranes prepared by the methods in Examples 1-11. The separation membrane used in this embodiment is from Example 6.

[0096] Experimental example:

[0097] 1. SEM characterization

[0098] Test sample: The separation membrane prepared in Example 4.

[0099] The test sample was moistened with ethanol, then fractured in liquid nitrogen, and the fracture surface was treated with gold sputtering and observed by SEM.

[0100] The separation membrane prepared by the method in Example 4 of this invention is the most representative, and its cross-sectional characterization is as follows: Figure 2 As shown, the upper half is the surface layer and the lower half is the middle layer, with a clear hierarchical structure.

[0101] 2. Mechanical property testing

[0102] Test sample: The separation membrane prepared in Examples 1-11.

[0103] The mechanical properties of the test samples were tested using an electronic tensile tester.

[0104] The mechanical properties of the separation membrane prepared by this invention are as follows: Figure 3 As shown, S1 is Example 1, S2 is Example 2, S3 is Example 3, S4 is Example 4, S5 is Example 5, S6 is Example 6, S7 is Example 7, S8 is Example 8, S9 is Example 9, S10 is Example 10, and S11 is Example 11. The difference between Examples 1-3 lies in the use of fillers. Hollow short fibers are used in Example 1, porous activated carbon is used in Example 2, and both hollow short fibers and porous activated carbon are used in Example 3. When only hollow short fibers or porous activated carbon are used as fillers, the mechanical properties of the resulting separation membranes are almost the same. When hollow short fibers and porous activated carbon are used together, the mechanical properties of the separation membrane decrease, indicating that increasing the amount of filler used will lead to a decrease in the mechanical properties of the separation membrane. In Examples 4-7, a three-layer separation membrane structure is formed, with hollow fiber membranes used in the middle layer, and the middle layer may or may not contain hollow fiber membranes. Using polyethyleneimine, the properties of the resulting separation membranes differ. In the methods of Examples 4-7, the composition of the base layer membrane and the surface layer membrane is largely the same. Therefore, the contribution of the base layer membrane and the surface layer membrane to the mechanical properties is treated as the same approximation. After using the filler, the use of polyethyleneimine increases the tensile strength of the resulting separation membrane. In Examples 8-11, a three-layer separation membrane structure is prepared using a hollow fiber membrane in the middle layer. At least isocyclohexylimine is used in the middle layer, and polyethyleneimine is used or not. The properties of the resulting separation membranes differ. When isocyclohexylimine and polyethyleneimine are used together, the tensile properties of the resulting separation membrane are optimal. When polyethyleneimine is not used, the tensile strength of the resulting separation membrane decreases significantly, indicating that isocyclohexylimine alone does not improve the performance of the separation membrane.

[0105] The separation membrane obtained by the method of the present invention has good mechanical properties, with a tensile strength of 10-35 MPa;

[0106] 3. Gas-liquid separation performance test

[0107] Test sample: The separation membrane prepared in Examples 1-11.

[0108] The separation performance of the above samples for n-butanol / water mixture was tested using a pervaporation apparatus. The flow rate of the original solution was 20 L / h, the pressure on the original solution side of the test sample was 400 Pa, and the effective area of ​​the test sample was 20 cm2. After running for 1.5 h until the steady state, the permeate was collected. The contents of n-butanol and water in the original solution and permeate were determined by gas chromatography.

[0109] The permeation flux of the separation membrane prepared by this invention is as follows: Figure 4 As shown, S1 is Example 1, S2 is Example 2, S3 is Example 3, S4 is Example 4, S5 is Example 5, S6 is Example 6, S7 is Example 7, S8 is Example 8, S9 is Example 9, S10 is Example 10, and S11 is Example 11. The difference between Examples 1-3 lies in the use of packing materials. Hollow short fibers are used in Example 1, porous activated carbon is used in Example 2, and both hollow short fibers and porous activated carbon are used in Example 3. When only hollow short fibers or porous activated carbon are used as packing materials, the permeation flux of the resulting separation membrane is not significantly different. When hollow short fibers and porous activated carbon are used together, the permeation flux of the separation membrane increases, indicating that increasing the amount of packing material used leads to improved permeation performance of the separation membrane. In Examples 4-7, a three-layer separation membrane structure is prepared, with hollow fiber membranes used in the middle layer, and other materials used simultaneously or not. The performance of the separation membranes prepared by using polyethyleneimine varies. In the methods of Examples 4-7, the composition of the base layer membrane and the surface layer membrane is largely the same. After using the filler, the use of polyethyleneimine improves the permeation flux performance of the prepared separation membrane. When polyethyleneimine is not used, the permeation flux of the prepared separation membrane is the lowest. In Examples 8-11, a three-layer separation membrane structure is prepared in the method of Examples 8-11. Hollow fiber membrane is used in the middle layer. At least isocyclohexylimide is used in the middle layer, and polyethyleneimine is used or not. The performance of the separation membranes prepared by this method varies. When isocyclohexylimide and polyethyleneimine are used together, the permeation flux of the obtained separation membrane is increased. When polyethyleneimine is not used, the permeation flux of the obtained separation membrane is greatly reduced, indicating that isocyclohexylimide alone does not have the effect of improving the permeation flux performance of the separation membrane.

[0110] The separation factor results of the separation membrane prepared by this invention are as follows: Figure 5As shown, S1 is Example 1, S2 is Example 2, S3 is Example 3, S4 is Example 4, S5 is Example 5, S6 is Example 6, S7 is Example 7, S8 is Example 8, S9 is Example 9, S10 is Example 10, and S11 is Example 11. The difference between Examples 1-3 lies in the use of packing materials. Hollow short fibers were used in Example 1, porous activated carbon was used in Example 2, and both hollow short fibers and porous activated carbon were used in Example 3. When only hollow short fibers or porous activated carbon were used as packing materials, the separation factors of the resulting membranes differed significantly. The separation factor of the membrane using hollow fibers as packing materials was higher than that using porous activated carbon. When both hollow short fibers and porous activated carbon were used together, the separation factor of the membrane increased significantly, indicating that increasing the amount of packing material used would improve the separation performance of the membrane. In Examples 4-7, a three-layer structure membrane was fabricated, with hollow fibers used in the middle layer. The performance of the separation membranes prepared by using or not using polyethyleneimine in the intermediate layer varies. In the methods of Examples 4-7, the composition of the base layer membrane and the surface layer membrane is largely the same. After using the filler, the use of polyethyleneimine improves the separation performance of the prepared membrane. When polyethyleneimine is not used, the separation factor of the prepared membrane is lower and the separation performance is poor. In Examples 8-11, a three-layer separation membrane is prepared by using a hollow fiber membrane in the intermediate layer. At least isocyclohexylimide is used in the intermediate layer, and polyethyleneimine is used or not. The performance of the prepared separation membranes varies. When isocyclohexylimide and polyethyleneimine are used together, the separation factor of the obtained membrane is higher and the separation performance is better. When polyethyleneimine is not used, the separation factor of the obtained membrane decreases significantly, indicating that isocyclohexylimide alone does not have the effect of improving the separation performance of the membrane.

[0111] The separation membrane prepared by this invention has a high permeation flux, ranging from 0.9 to 2 kg·m³. -2 h -1 The separation membrane has good separation performance, with a separation factor of 400-1400.

[0112] The above embodiments are for illustrative purposes only and are not intended to limit the invention. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, all equivalent technical solutions also fall within the scope of this invention, and the patent protection scope of this invention should be defined by the claims.

Claims

1. A method for treating the reaction of purge gas from an organic alcohol apparatus, comprising: The purge gases from the organic alcohol hydrogenation unit and the carbonyl synthesis unit are mixed and reacted in a reactor to produce crude alcohol-water product and low-concentration purge gases. The crude alcohol-water product is initially separated by a separation membrane, and the low-concentration purge gas is sent to the waste gas combustion system for heat recovery. The separation membrane uses Pebax as a substrate, in which granular porous activated carbon and / or hollow short fibers are dispersed; the porous activated carbon is made from corn stalk powder through pretreatment and carbonization; the hollow short fibers are made from a spinning casting solution containing polyacrylic acid and a core solution through a dry-jet-wet spinning method. The main offgas composition of the carbonyl synthesis unit is ethylene, hydrogen, and carbon monoxide. The main offgassing gases from the hydrogenation unit are hydrogen and methane.

2. The method for treating the off-gas reaction of an organic alcohol device according to claim 1, characterized in that: The separation membrane is divided into three layers: upper, middle, and lower. The main material of the middle layer is hollow short fiber, and the middle layer does not contain Pebax.

3. The method for treating the off-gas reaction of an organic alcohol device according to claim 2, characterized in that: The separation membrane contains a cross-linked structure of polyethyleneimine, which is generated by the combination of polyethyleneimine with carboxyl groups on porous activated carbon and / or hollow short fibers.

4. A method for preparing a separation membrane for use in the off-gas reaction treatment method of an organic alcohol apparatus according to any one of claims 1-3, comprising: The filler is added to a solution containing Pebax, stirred and dispersed to prepare a casting solution, and then a separation membrane is obtained by membrane preparation. The filler is granular porous activated carbon and / or hollow short fibers. The porous activated carbon is made from corn stalk powder through pretreatment and carbonization. The hollow short fibers are made from a spinning casting solution containing polyacrylic acid and a core solution through a dry-jet-wet spinning method.

5. The method for preparing the separation membrane according to claim 4, characterized in that: The filler is added to a solution containing Pebax and stirred to disperse it to prepare a casting solution. The substrate layer is obtained by film preparation. A layer of hollow short fibers is laid on the substrate layer, and then a solution containing or not containing polyethyleneimine is added and dried to prepare an intermediate layer. A casting solution containing or without polyethyleneimine is added to the intermediate layer and dried to form the surface layer, thus obtaining the separation membrane.

6. The method for preparing the separation membrane according to claim 5, characterized in that: The amount of filler used is 20-60 wt% of Pebax.

7. The method for preparing the separation membrane according to claim 6, characterized in that: In the preparation of the intermediate layer membrane, the amount of polyethyleneimine used is 20-50 wt% of the hollow short fibers.

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