Method for recovering waste liquid of butanol and octanol device

Abstract

The invention provides a method for recovering butanol and octanol waste liquid. The method comprises the following steps: (1) rectifying the butanol and octanol waste liquid in a rectifying tower, extracting C4-C10 light components from the tower top, removing macromolecular impurities from the light components through membrane separation to obtain tower top refined liquid, extracting heavy components of C12 and above from a tower kettle, and removing macromolecular impurities of C16 and above from the heavy components through membrane separation to obtain tower kettle refined liquid; (2) mixing the tower top refined liquid and the tower kettle refined liquid, pressurizing, mixing with high-pressure hydrogen, and preheating; (3) carrying out hydrogenation reaction on the preheated reaction material, and carrying out rectification separation on the material after hydrogenation reaction to obtain butanol and octanol; wherein the hydrogenation catalyst is a hierarchical pore molecular sieve loaded with copper, nickel and zinc. According to the recovery method, the conversion rate of high-carbon esters can be obviously improved, and meanwhile, the selectivity of butanol and octanol is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of organic chemical industry, and more specifically, to a method for recovering waste liquid from a butanol and octanol device through hydrogenation and refining process. Background Art

[0002] The production process of the butanol and octanol unit is mainly to react propylene with synthesis gas for hydroformylation to generate mixed butyraldehyde, which is separated to produce n-isobutyraldehyde, of which n-butyraldehyde is hydrogenated to produce butanol, and n-butyraldehyde is condensed to produce 2-ethyl-2-hexenal, which is then hydrogenated to produce octanol.

[0003] During the hydrogenation reaction, aldehydes are easily disproportionated in the reactor to generate corresponding esters and other heavy components. The waste liquid has complex components and is difficult to recover, especially high-carbon esters. Currently, the main treatment method is incineration, which is not conducive to environmental protection and energy consumption.

[0004] Patent CN101973846B discloses a method for producing mixed butanol and crude octanol using waste liquid from a butanol and octanol plant as raw material. The waste liquid is first separated according to different components, and then the aldehydes are hydrogenated to produce butanol and octanol, which are then purified by complex separation methods, resulting in high energy consumption.

[0005] Patent CN112321386A discloses a method for hydrogenating butyl octanol waste liquid, using an alkaline auxiliary agent and catalytic hydrogenation to recover alcohol, but the hydrogenation process cannot complete the recovery of ester waste liquid, and the catalyst life is short, requiring frequent catalyst replacement.

[0006] Patent CN 113735688B discloses a method for recovering butanol from waste liquid of a butanol plant through hydrogenation. The invention was developed by our team and can efficiently recover esters in waste liquid, especially butyl butyrate, through hydrogenation. However, the method is not suitable for waste liquid produced by a butanol and octanol plant proposed in the present invention for the following reasons: In the subsequent development process, when the butanol and octanol waste liquid was hydrogenated using the hydrogenation catalyst, we found that the catalyst life was short and the yield of the main product was low. After thermal stability testing of the raw materials, it was found that the waste liquid contained more C16 and above components. Under this atmosphere, due to the high reaction temperature, some C10-C16 components were thermally cracked, and in addition to producing some non-condensable gases, some short-chain olefins (C4-C6) were also produced, affecting the yield of the product C4 and C8 alcohols. Moreover, substances above C16 are more easily adsorbed on the catalyst surface. Due to the presence of local hot spots, these higher molecular substances are easily carbonized and cover the catalyst active sites, resulting in a reduction in the catalyst life. Summary of the invention

[0007] In order to solve the above-mentioned problems, the purpose of the present invention is to provide a method for recycling high-carbon esters in the waste liquid of the butanol unit, which can significantly extend the service life of the catalyst and significantly reduce the material consumption of the butanol unit.

[0008] In order to achieve the purpose of the present invention, the present invention adopts the following technical solutions:

[0009] A method for recovering butyl octanol waste liquid, characterized in that it comprises the following steps:

[0010] (1) distilling the butyl octanol waste liquid in a distillation tower, extracting C4-C10 light components from the tower top, removing macromolecular impurities from the light components through membrane separation to obtain a tower top refined liquid, extracting C12 and above heavy components from the tower bottom, removing macromolecular impurities of C16 and above from the heavy components through membrane separation to obtain a tower bottom refined liquid;

[0011] (2) mixing the top refined liquid and the bottom refined liquid, pressurizing them, and mixing them with high-pressure hydrogen for preheating;

[0012] (3) subjecting the preheated reaction materials to a hydrogenation reaction, and subjecting the materials after the hydrogenation reaction to distillation separation to obtain butanol and octanol;

[0013] Wherein, the hydrogenation catalyst is a multi-level porous molecular sieve loaded with copper, nickel and zinc.

[0014] In some embodiments, the butanol waste liquid comes from a butanol unit, and the butanol waste liquid contains 15-20% butanol, 15-20% octanol, 25-30% C8 esters, 5-7% C10 ketones, 4-6% C12 esters, 10-15% C16 esters, 1-3% other C3-C8 substances, 2-4% other C8-C16 substances, and 10-15% C16 and above substances.

[0015] In some specific embodiments, in step (1), the light component is treated by a membrane separation device, and the membrane separation device uses a nanofiltration membrane with a molecular weight cutoff of ≥150;

[0016] The heavy component is processed by a membrane separation device, and the membrane separation device uses a nanofiltration membrane with a molecular weight cutoff of ≥250.

[0017] In some specific embodiments, the distillation tower has 20 to 30 theoretical plates, preferably 24 to 26 theoretical plates;

[0018] The absolute pressure at the top of the distillation tower is 1-20 kPa, preferably 5-10 kPa; the operating temperature at the top of the tower is 60-80°C, the temperature at the bottom of the tower is 140-200°C, and the reflux ratio is 1-15, preferably 6-10;

[0019] Preferably, the feed tray position is the 2nd to 6th tray from top to bottom.

[0020] In some specific embodiments, in step (2), the top refined liquid and the bottom refined liquid are mixed in a mixer;

[0021] Preferably, the pressure is increased to 1-4 MPa by a booster pump and then mixed with high-pressure hydrogen before entering a preheater for preheating. More preferably, the preheating temperature is 100-180°C.

[0022] In some embodiments, in step (3), the mass flow ratio of hydrogen to the reaction material in the hydrogenation reaction is 0.07 to 0.2;

[0023] Preferably, the hydrogenation reaction is carried out at 130-210°C and 1-4 MPaG;

[0024] More preferably, the feed space velocity of the hydrogenation reaction is 1 to 4 h -1 ;

[0025] Further preferably, the hydrogenation reaction is carried out in a trickle bed hydrogenation reactor.

[0026] In some embodiments, the total loading of metal components in the hydrogenation catalyst is 1 to 1.5 wt%;

[0027] Preferably, the molar ratio of copper, nickel and zinc supported in the hydrogenation catalyst is 1:(0.2-0.5):(0.1-0.3).

[0028] In some specific embodiments, during the preparation process of the hydrogenation catalyst, the molecular sieve is first impregnated with an organic base solution to improve the pore structure of the molecular sieve, and then the precursor is dissolved in water to form a solution, and the pretreated molecular sieve is added thereto for impregnation and calcination to obtain a multi-level porous molecular sieve loaded with copper, nickel and zinc;

[0029] Wherein, the precursor includes a copper-containing precursor, a nickel-containing precursor and a zinc-containing precursor;

[0030] Preferably, the copper-containing precursor is selected from copper nitrate, the nickel-containing precursor is selected from nickel nitrate, and the zinc-containing precursor is selected from zinc acetate;

[0031] More preferably, the molecular sieve is selected from SBA type molecular sieve or MCM type molecular sieve, preferably SBA-15 molecular sieve.

[0032] In some embodiments, the organic alkaline solution is selected from quaternary ammonium bases, preferably one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide;

[0033] Preferably, the concentration of the organic base solution is 0.1 to 0.3 M;

[0034] More preferably, the volume mass ratio of the organic alkali solution to the molecular sieve is preferably 20 to 30 ml of alkali solution / g of molecular sieve, the temperature at which the organic alkali solution is impregnated with the molecular sieve is 60 to 80° C., and the treatment time is 1 to 4 hours, preferably 1.5 to 2.5 hours;

[0035] Further preferably, the pretreated molecular sieve is added and then impregnated in a nitrogen atmosphere, the impregnation temperature is 50-80°C, preferably 65-75°C, the impregnation time is 15-20h, preferably 16-17h; the volume mass ratio of the aqueous solution formed by the precursor to the molecular sieve is 10-15ml alkali solution / g molecular sieve;

[0036] Further preferably, the calcination is carried out in an air atmosphere, with the temperature rising from 30°C to 200°C at a heating rate of 10°C / min, maintained for 1 hour, and then rising to 450-600°C at 5°C / min, and maintained for 12-25 hours.

[0037] In some specific embodiments, after the hydrogenation reaction is completed, the reaction materials are passed through a gas-liquid separation tank to remove the residual hydrogen in the product, and the hydrogenation product is sent to a distillation tower for separation;

[0038] Preferably, the distillation tower is a packed tower, and the number of theoretical plates of the distillation tower is 8 to 12, preferably 9 to 10;

[0039] The absolute pressure at the top of the distillation tower is 35-60 kPa, preferably 40-50 kPa; the operating temperature at the top is 65-110°C, preferably 90-100°C; the bottom temperature is 150-200°C, preferably 160-180°C; and the reflux ratio is 1-20, preferably 2-4.

[0040] The technical solution provided by the present invention has the following beneficial effects:

[0041] According to the waste liquid composition of the butanol and octanol device, the present invention provides a method for recycling ester substances, especially high-carbon esters, in the waste liquid, so that the life of the catalyst is greatly increased and the efficiency of the device is effectively improved.

[0042] In the recovery method of the present invention, the nanofiltration membrane is used to effectively remove impurities in the heavy component waste liquid that cannot be hydrogenated and affect the life of the catalyst; at the same time, liquid phase hydrogenation is adopted in the hydrogenation operation process, and the operating temperature is low and the conditions are mild, which can not only efficiently recover high-carbon esters, but also effectively avoid the decomposition of the heavy component substances, and further reduce material consumption and energy consumption. DETAILED DESCRIPTION

[0043] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0044] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the invention belongs. The term "and / or" as may be used herein includes any and all combinations of one or more of the associated listed items.

[0045] The method for recovering butyl octanol waste liquid provided by the present invention comprises the following steps:

[0046] (1) distilling the butyl octanol waste liquid in a distillation tower, extracting C4-C10 light components from the tower top, removing macromolecular impurities from the light components through membrane separation to obtain a tower top refined liquid, extracting C12 and above heavy components from the tower bottom, removing macromolecular impurities of C16 and above from the heavy components through membrane separation to obtain a tower bottom refined liquid;

[0047] (2) mixing the top refined liquid and the bottom refined liquid, pressurizing them, and mixing them with high-pressure hydrogen for preheating;

[0048] (3) subjecting the preheated reaction materials to a hydrogenation reaction, and subjecting the materials after the hydrogenation reaction to distillation separation to obtain butanol and octanol;

[0049] Wherein, the hydrogenation catalyst is a multi-level porous molecular sieve loaded with copper, nickel and zinc.

[0050] The researchers of the present invention studied the thermal stability of the heavy component waste liquid and found that when the recovery and treatment temperature of the waste liquid rises to above 240°C, the system pressure rises rapidly. Analysis of samples before and after the test shows that the content of some C10-C16 components is significantly reduced, indicating that thermal cracking occurs. In addition to producing some non-condensable gases, some short-chain olefins (C4-C6) are also produced. Therefore, when recovering C10 and above heavy components, the hydrogenation reaction temperature must be controlled within a reasonable temperature range.

[0051] In the implementation of the recovery method of the present invention, the butanol waste liquid comes from the butanol unit, and the butanol waste liquid contains 15-20% butanol, 15-20% octanol, 25-30% C8 ester, 5-7% C10 ketone, 4-6% C12 ester, 10-15% C16 ester, 1-3% other C3-C8 substances, 2-4% other C8-C16 substances, and 10-15% C16 and above substances.

[0052] Preferably, in step (1), the light component is treated by a membrane separation device, such as a nanofiltration membrane separation device, which uses a nanofiltration membrane with a molecular weight cutoff of ≥150; the heavy component is treated by a membrane separation device, which uses a nanofiltration membrane with a molecular weight cutoff of ≥250. In the specific implementation process, the membrane structure can be adjusted to allow substances below a specific molecular weight to pass through.

[0053] In a specific embodiment of the present invention, the distillation tower used in step (1) is a packed tower, using two-stage packing, the number of theoretical plates is 20 to 30, preferably 24 to 26; the absolute pressure at the top of the distillation tower is 1 to 20 kPa, preferably 5 to 10 kPa; the top operating temperature is 60 to 80°C, the bottom temperature is 140 to 200°C, and the reflux ratio is 1 to 15, preferably 6 to 10; preferably, the feed plate position is the 2nd to 6th plate from top to bottom.

[0054] In a specific embodiment of the present invention, the top refined liquid and the bottom refined liquid in step (2) are mixed in a mixer; after being pressurized to 1-4 MPa by a booster pump, they are mixed with high-pressure hydrogen and enter a preheater with electric heating for preheating, and the preheating temperature is more preferably 100-180°C.

[0055] In a specific embodiment of the present invention, the preheated reaction materials flow downward and enter a trickle bed hydrogenation reactor for hydrogenation reaction, and the trickle bed reactor is filled with a hydrogenation catalyst. In some specific embodiments, the feed ratio of hydrogen to the heavy components in the reaction materials in the hydrogenation reaction in step (3) is 6 to 15, for example, 8, 10, 12; preferably, the hydrogenation reaction is carried out at 130 to 210°C and 1 to 4 MPaG; further, the feed space velocity of the hydrogenation reaction is 1 to 4 h -1 .

[0056] In some specific embodiments, the hydrogenation catalyst is a modified molecular sieve loaded with copper, nickel and zinc components, wherein the total loading of the metal components is 1-1.5wt%, for example, 1.2wt%, 1.4wt%; more specifically, the molar ratio of copper, nickel and zinc loaded in the hydrogenation catalyst is 1:(0.2-0.5):(0.1-0.3), for example, 1:0.3:0.2, 1:0.4:0.2, 1:0.3:0.3.

[0057] The hydrogenation catalyst in the recovery method of the present invention can be prepared by an impregnation method, which can be adopted as follows: first, the molecular sieve is impregnated with an organic alkaline solution to improve the pore structure of the molecular sieve, and then the precursor (copper-containing precursor, nickel-containing precursor and zinc-containing precursor) is dissolved in water to form a solution, and the pretreated molecular sieve is added thereto for impregnation and calcination to obtain a multi-level porous molecular sieve loaded with copper, nickel and zinc.

[0058] In some embodiments, the molecular sieve is first impregnated with an organic alkali solution for pretreatment to improve the pore structure of the molecular sieve, and the organic alkali is selected from quaternary ammonium bases containing different carbon chain lengths, preferably one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide. Specifically, the concentration of the organic alkali solution is 0.1 to 0.3M; the volume mass ratio of the organic alkali solution to the molecular sieve is preferably 20 to 30 ml of alkali solution / g of molecular sieve, the temperature of the organic alkali solution impregnating the molecular sieve is 60 to 80°C, and the treatment time is 1 to 4 hours, preferably 1.5 to 2.5 hours.

[0059] In some specific embodiments, the molecular sieve is selected from SBA type molecular sieve, MCM type molecular sieve, preferably SBA-15 molecular sieve.

[0060] In some embodiments, a copper-containing precursor, a nickel-containing precursor and a zinc-containing precursor are dissolved in water to form a solution, to which the pretreated molecular sieve is added and impregnated under a nitrogen atmosphere, the immersion temperature is 50 to 80° C., preferably 65 to 75° C., and the immersion time is 15 to 20 hours, preferably 16 to 17 hours; specifically, the volume mass ratio of the aqueous solution formed by the precursor to the molecular sieve is 10 to 15 ml of alkali solution / g of molecular sieve.

[0061] In some embodiments, after the impregnation, the water is evaporated and calcined in an air atmosphere, specifically, the temperature is increased from 30°C to 200°C at a heating rate of 10°C / min, maintained for 1 hour, and then increased to 450-600°C at 5°C / min, and maintained for 12-25 hours.

[0062] In some embodiments, after the hydrogenation reaction is completed, the reaction materials are detoxified from the residual hydrogen in the product in a gas-liquid separation tank, and the hydrogenation product is sent to a distillation tower for separation; specifically, the distillation tower is a packed tower with 8 to 12 theoretical plates, preferably 9 to 10 plates; the absolute pressure at the top of the distillation tower is 35 to 60 kPa, preferably 40 to 50 kPa; the operating temperature at the top of the tower is 65 to 110°C, preferably 90 to 100°C; the bottom temperature is 150 to 200°C, preferably 160 to 180°C; the reflux ratio is 1 to 20, preferably 2 to 4.

[0063] The present invention is further described below by means of specific examples, but it should not be understood that the present invention is limited thereto.

[0064] Where specific experimental steps or conditions are not specified in the examples, the corresponding conventional experimental steps or conditions in the art can be used. The reagents used without specifying the manufacturer are all conventional reagents available in the art.

[0065] Source of raw materials:

[0066] SBA-15 molecular sieve: pore size 6-11 nm, purchased from Beijing Inokai.

[0067] The sample analysis was carried out by Agilent chromatography online determination. The analysis method was as follows: temperature program was used. The specific program was as follows: column temperature: 50°C for 3 min, heated to 60°C at 4°C / min and held for 2 min, heated to 220°C at 10°C / min and held for 1 min, heated to 350°C at 30°C / min and held for 5 min.

[0068] Example 1

[0069] Preparation of catalyst: Add 5L 0.1M tetramethylammonium hydroxide solution to a hydrothermal autoclave, then add 250g commercial SBA-15 molecular sieve, heat to 70°C, stir for 1.5h, and wash with deionized water and dry after the alkali treatment.

[0070] Dissolve 5.1g of copper nitrate trihydrate, 1.2g of nickel nitrate hexahydrate, and 1.2g of anhydrous zinc acetate in 2L of deionized water, add 200g of the above-mentioned alkali-treated SBA-15 molecular sieve, replace the reactor with N2, heat to 65°C under stirring, impregnate for 16h, evaporate the water after impregnation, wash and dry the impregnated catalyst, and roast in air atmosphere. The specific roasting method is: start from 30°C and increase to 200°C at 10°C / min, keep for 1h, then increase to 500°C at 5°C / min, keep for 16h, press and screen out 20-mesh granular catalyst after roasting, and the total loading of metal components is 1%. Before using the catalyst, use 300°C hydrogen reduction for 24h, and the hydrogen pressure is 20kPaG.

[0071] The composition of the butanol and octanol waste liquid used below is: 16.5% butanol, 15.2% octanol, 26.6% butyl butyrate, 6.1% C10 ketone, 5.4% C12 ester, 14.1% C16 ester, 1.5% other C3-C8, 3.8% other C8-C16, and 10.8% C16 and above substances.

[0072] (1) The waste liquid from the 1,2-butanol unit is distilled in a distillation tower to roughly separate light and heavy components. The distillation tower is a packed tower with two-stage packing, 24 theoretical plates, 5 kPa (absolute pressure) at the top of the tower, 70°C at the top of the tower, 170°C at the bottom of the tower, and a reflux ratio of 6; the feed position is the second plate from the top.

[0073] The light components taken from the top of the tower are passed through a nanofiltration membrane device with a molecular weight cutoff of ≥150 to remove large molecular impurities such as C10 ketone that cannot be recovered. The heavy components taken from the bottom of the tower are passed through a nanofiltration membrane device with a molecular weight cutoff of ≥250 to remove heavy components above C16 to avoid deactivation of the hydrogenation catalyst.

[0074] The inlet and outlet pressure difference of the above-mentioned membrane equipment is maintained at 1MPa, and the operating temperature is 60°C; specifically, the membrane equipment for refining the top component allows substances with a molecular weight of less than 150 to pass through, and the membrane equipment for refining the heavy component in the bottom of the tower allows substances with a molecular weight of 250 and below to pass through.

[0075] (2) The refined liquid from the top of the tower and the refined liquid from the bottom of the tower are mixed, pressurized to 1.8 MPa by a booster pump, mixed evenly with 2 MPa hydrogen in a mixer and preheated to 120°C;

[0076] (3) The preheated reaction material was introduced into a trickle bed reactor filled with a liquid phase hydrogenation catalyst, the catalyst loading was 30 mL, the reaction temperature was 150°C, the reaction pressure was 1.8 MPa, and the feed space velocity was 2 h -1 The hydrogenation reaction is carried out under the conditions of ; wherein the mass flow ratio of hydrogen to the reaction material is 0.09;

[0077] The material at the outlet of the hydrogenation reactor is cooled and sent to the gas-liquid separation tank to remove the residual hydrogen in the product. The operating temperature of the gas-liquid separation tank is 60°C and the operating pressure is 2MPaG. The hydrogenation reaction products are separated in a distillation tower. The theoretical number of plates of the distillation tower is 10, the top pressure of the distillation tower is 50kPa, the top operating temperature is 100°C, the bottom temperature is 170°C, the reflux ratio is controlled to 2, and the feed position is located at the 5th plate from the top. The butanol product is extracted from the top of the distillation tower, and the octanol product is extracted from the bottom of the tower. Subsequent logistics can be returned to the main device for further refining.

[0078] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, the conversion rate of the reactants and the selectivity of butanol and octanol were calculated, and a long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0079] Example 2

[0080] The waste liquid of the butanol unit was treated by referring to the method of Example 1, except that tetraethylammonium hydroxide was used as the organic base to treat the molecular sieve during the catalyst preparation process.

[0081] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, and the reactant conversion rate and the selectivity of butanol and octanol were calculated. A long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0082] Example 3

[0083] The waste liquid of the butanol and octanol unit was treated with reference to Example 1, the only difference being that tetrapropylammonium hydroxide was used as the organic base to treat the molecular sieve during the catalyst preparation process.

[0084] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, and the reactant conversion rate and the selectivity of butanol and octanol were calculated. A long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0085] Example 4

[0086] Preparation of catalyst: Add 5L 0.1M tetramethylammonium hydroxide solution and 250g commercial SBA-15 molecular sieve into a hydrothermal kettle, heat to 70°C, stir for 1.5h, and wash with deionized water and dry after the alkali treatment.

[0087] 6g of copper nitrate trihydrate, 1.2g of nickel nitrate hexahydrate, and 1.2g of anhydrous zinc acetate were dissolved in 2L of deionized water, and 200g of SBA-15 molecular sieve treated with alkali was added. The reactor was replaced with N2, heated to 65°C under stirring conditions, and impregnated for 16 hours. After the impregnation was completed, the water was evaporated; the impregnated catalyst was washed and dried, and roasted in an air atmosphere. The specific roasting method was: starting from 30°C, the temperature was increased by 10°C / min to 200°C, maintained for 1 hour, and then increased to 500°C at 5°C / min, maintained for 16 hours. After the roasting was completed, a 20-mesh granular catalyst was pressed and sieved, and the total loading of the metal component was 1.12%. Before using the catalyst, it was reduced with hydrogen at 300°C for 24 hours, and the hydrogen pressure was 20kPaG.

[0088] The composition of the butanol and octanol waste liquid is: 15.8% butanol, 15.4% octanol, 26.9% butyl butyrate, 5.6% C10 ketone, 5.9% C12 ester, 13.8% C16 ester, 1.6% other C3-C8, 4.1% other C8-C16, and 10.9% substances above C16.

[0089] (1) The waste liquid from the 1,2-butanol unit is distilled in a distillation tower to roughly separate light and heavy components. The distillation tower is a packed tower with two-stage packings, 27 theoretical plates, 8 kPa (absolute pressure) at the top of the tower, 80°C at the top of the tower, 185°C at the bottom of the tower, and a reflux ratio of 10; the feed position is the third plate from the top.

[0090] The light components taken from the top of the tower are passed through a nanofiltration membrane device with a molecular weight cutoff of ≥150 to remove large molecular impurities such as C10 ketone that cannot be recovered. The heavy components taken from the bottom of the tower are passed through a nanofiltration membrane device with a molecular weight cutoff of ≥250 to remove heavy components above C16 to avoid deactivation of the hydrogenation catalyst.

[0091] The inlet and outlet pressure difference of the above-mentioned membrane equipment is maintained at 1MPa, and the operating temperature is 60°C; the membrane equipment used for refining the top component allows substances with a molecular weight of less than 150 to pass through, and the membrane equipment used for refining the heavy component in the bottom of the tower allows substances with a molecular weight of 250 and below to pass through.

[0092] (2) The refined liquid from the top of the tower and the refined liquid from the bottom of the tower are mixed, pressurized to 1.8 MPa by a booster pump, mixed evenly with 2 MPa hydrogen in a mixer and preheated to 140°C;

[0093] (3) The preheated reaction material was introduced into a trickle bed reactor filled with a liquid phase hydrogenation catalyst. The catalyst loading was 30 mL, the reaction temperature was 150 ° C, the reaction pressure was 1.8 MPa, and the feed space velocity was 2 h -1 The hydrogenation reaction was carried out under the conditions of ; wherein the mass flow ratio of hydrogen to the reaction material was 0.12;

[0094] The material at the outlet of the hydrogenation reactor is cooled and sent to the gas-liquid separation tank to remove the residual hydrogen in the product. The operating temperature of the gas-liquid separation tank is 60°C and the operating pressure is 2MPaG. The hydrogenation reactants are separated in a distillation tower. The theoretical number of plates of the distillation tower is 10, the top pressure of the distillation tower is 50kPa, the top operating temperature is 100°C, the bottom temperature is 170°C, the reflux ratio is controlled to 2, and the feed position is located at the 5th plate from the top. The butanol product is extracted from the top of the distillation tower, and the octanol product is extracted from the bottom of the tower. Subsequent logistics can be returned to the main device for further refining.

[0095] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, the conversion rate of the reactants and the selectivity of butanol and octanol were calculated, and a long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0096] Example 5

[0097] Preparation of catalyst: Add 5L 0.1M tetramethylammonium hydroxide solution to a hydrothermal autoclave, then add 250g commercial SBA-15 molecular sieve, heat to 70°C, stir for 1.5h, and wash with deionized water and dry after the alkali treatment.

[0098] Dissolve 7g of copper nitrate trihydrate, 1.2g of nickel nitrate hexahydrate, and 1.2g of anhydrous zinc acetate in 2L of deionized water, add 200g of SBA-15 molecular sieve treated with alkali, replace the reactor with N2, heat to 65°C under stirring, impregnate for 16h, evaporate the water after impregnation, wash and dry the impregnated catalyst, and roast in air atmosphere. The specific roasting method is: start from 30°C and increase to 200°C at 10°C / min, keep for 1h, then increase to 600°C at 5°C / min, keep for 14h, press and screen out 20-mesh granular catalyst after roasting, and the total loading of metal components is 1.25%. Before using the catalyst, use 300°C hydrogen reduction for 24h, and the hydrogen pressure is 20kPaG.

[0099] The composition of the butanol and octanol waste liquid is: 16.5% butanol, 15.2% octanol, 26.6% butyl butyrate, 6.1% C10 ketone, 5.4% C12 ester, 14.1% C16 ester, 1.5% other C3-C8, 3.8% other C8-C16, and 10.8% substances above C16.

[0100] (1) The waste liquid from the 1,2-butanol unit is distilled in a distillation tower to roughly separate light and heavy components. The distillation tower is a packed tower with two-stage packing, 24 theoretical plates, 5 kPa (absolute pressure) at the top of the tower, 70°C at the top of the tower, 170°C at the bottom of the tower, and a reflux ratio of 6; the feed position is the second plate from the top.

[0101] The light components taken from the top of the tower are passed through a nanofiltration membrane device with a molecular weight cutoff of ≥150 to remove large molecular impurities such as C10 ketone that cannot be recovered. The heavy components taken from the bottom of the tower are passed through a nanofiltration membrane device with a molecular weight cutoff of ≥250 to remove heavy components above C16 to avoid deactivation of the hydrogenation catalyst.

[0102] The inlet and outlet pressure difference of the above-mentioned membrane equipment is maintained at 1MPa, and the operating temperature is 60°C; the membrane equipment used for refining the top component allows substances with a molecular weight of less than 150 to pass through, and the membrane equipment used for refining the heavy component in the bottom of the tower allows substances with a molecular weight of 250 and below to pass through.

[0103] (2) The refined liquid from the top of the tower and the refined liquid from the bottom of the tower are mixed, pressurized to 1.8 MPa by a booster pump, mixed evenly with 2 MPa hydrogen in a mixer and preheated to 130°C;

[0104] (3) The preheated reaction material was introduced into a trickle bed reactor filled with a liquid phase hydrogenation catalyst, the catalyst loading amount was 30 mL, the reaction temperature was 170 ° C, the reaction pressure was 2.0 MPa, and the feed space velocity was 2 h -1 The hydrogenation reaction was carried out under the conditions of ; wherein the mass flow ratio of hydrogen to the reaction material was 0.16;

[0105] The material at the outlet of the hydrogenation reactor is cooled and sent to the gas-liquid separation tank to remove the residual hydrogen in the product. The operating temperature of the gas-liquid separation tank is 60°C and the operating pressure is 2MPaG. The hydrogenation reaction products are separated in a distillation tower. The number of theoretical plates of the distillation tower is 9, the top pressure of the distillation tower is 40kPa, the top operating temperature is 95°C, the bottom temperature is 160°C, the reflux ratio is controlled to 15, and the feed position is located at the third plate from the top. The butanol product is extracted from the top of the distillation tower, and the octanol product is extracted from the bottom of the tower. Subsequent logistics can be returned to the main device for further refining.

[0106] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, the conversion rate of the reactants and the selectivity of butanol and octanol were calculated, and a long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0107] Example 6

[0108] The waste liquid from the butanol unit was treated with reference to Example 1, except that in the preparation of the catalyst, no organic base was used to impregnate the commercial SBA-15 molecular sieve, and the precursor was directly dissolved in water to form a solution, to which the molecular sieve was added for impregnation and calcination to obtain the molecular sieve loaded with the metal component.

[0109] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, and the reactant conversion rate and the selectivity of butanol and octanol were calculated. A long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0110] Comparative Example 1

[0111] The waste liquid of the butanol and octanol device is treated with reference to Example 1, except that the heavy components extracted from the bottom of the distillation tower in step (1) are not subjected to membrane separation to remove impurities.

[0112] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, and the reactant conversion rate and the selectivity of butanol and octanol were calculated. A long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0113] Comparative Example 2

[0114] The waste liquid of the butanol unit was treated with reference to Example 1, except that the gas phase hydrogenation catalyst was prepared with reference to the method of patent CN 113735688B, and the hydrogenation reactor was changed from a trickle bed reactor to a fixed bed reactor. The temperature of the hydrogenation reaction was 270° C., the reaction pressure was 4 MPa, and the gas phase hydrogenation reaction was carried out. The other treatment methods were consistent with Example 1.

[0115] The composition test was carried out on the material at the outlet of the gas-liquid separation tank, and the reactant conversion rate and the selectivity of butanol and octanol were calculated. A long-term operation test was carried out. When the selectivity of either butanol or octanol decreased to 80%, the operation was stopped and the operation time was recorded. The results are shown in Table 1.

[0116] Table 1

[0117]

[0118] It can be seen from the data of Examples 1 to 3 in Table 1 that the method for recovering butanol and octanol waste liquid provided by the present invention can significantly improve the conversion rate of high-carbon esters (for example, C8 esters, C12 esters and C16 esters), while improving the selectivity of butanol and octanol; further, in the recovery method provided by the present invention, the molecular sieve modified by the organic base (quaternary ammonium base) during the preparation of the hydrogenation catalyst used can extend the service life of the catalyst to varying degrees, and the quaternary ammonium base has different molecular weights and different catalyst modification effects. The catalyst modified with a quaternary ammonium base of a larger molecular weight has a slightly lower product yield, but a longer catalyst life; it can be seen from Examples 1, 4, and 5 that the copper component is an effective metal component of the catalyst, and the increase in its content can improve the reaction activity of the catalyst.

[0119] It can be seen from the data of Example 1 and Comparative Example 1 that if membrane equipment is not used to remove impurities, the catalyst activity and catalyst life will be significantly reduced; it can be seen from the data of Example 1 and Comparative Example 2 that if a gas phase hydrogenation reaction is used, due to the relatively poor reaction conditions, the hydrogenation effect of substances above C12 is very unsatisfactory and decomposes into other substances, and the catalyst life is much shorter than the recovery method of liquid phase hydrogenation provided by the present invention.

Claims

1. A method for recovering butyl octanol waste liquid, characterized in that: The steps include: (1) distilling the butyl octanol waste liquid in a distillation tower, extracting C4-C10 light components from the tower top, removing macromolecular impurities from the light components through membrane separation to obtain a tower top refined liquid, extracting C12 and above heavy components from the tower bottom, removing macromolecular impurities of C16 and above from the heavy components through membrane separation to obtain a tower bottom refined liquid; (2) mixing the top refined liquid and the bottom refined liquid, pressurizing them, and mixing them with high-pressure hydrogen for preheating; (3) subjecting the preheated reaction materials to a hydrogenation reaction, and subjecting the materials after the hydrogenation reaction to distillation separation to obtain butanol and octanol; Wherein, the hydrogenation catalyst is a multi-level porous molecular sieve loaded with copper, nickel and zinc.

2. The recycling method according to claim 1, characterized in that: The butanol waste liquid comes from a butanol device, and contains 15-20% butanol, 15-20% octanol, 25-30% C8 ester, 5-7% C10 ketone, 4-6% C12 ester, 10-15% C16 ester, 1-3% other C3-C8 substances, 2-4% other C8-C16 substances, and 10-15% C16 and above substances.

3. The recycling method according to claim 2, characterized in that: In step (1), the number of theoretical plates of the distillation tower is 20 to 30, preferably 24 to 26; The absolute pressure at the top of the distillation tower is 1-20 kPa, preferably 5-10 kPa; the operating temperature at the top of the tower is 60-80°C, the temperature at the bottom of the tower is 140-200°C, and the reflux ratio is 1-15, preferably 6-10; Preferably, the feed tray position is the 2nd to 6th tray from top to bottom.

4. The recycling method according to claim 3, characterized in that: The light component is treated by a membrane separation device, and the membrane separation device uses a nanofiltration membrane with a molecular weight cutoff of ≥150; The heavy component is processed by a membrane separation device, and the membrane separation device uses a nanofiltration membrane with a molecular weight cutoff of ≥250.

5. The recovery method according to any one of claims 1 to 4, characterized in that: In step (2), the top refined liquid and the bottom refined liquid are mixed in a mixer; Preferably, the pressure is increased to 1-4 MPa by a booster pump and then mixed with high-pressure hydrogen before entering a preheater for preheating. More preferably, the preheating temperature is 100-180°C.

6. The recovery method according to any one of claims 1 to 5, characterized in that: In step (3), the mass flow ratio of hydrogen to the reaction material in the hydrogenation reaction is 0.07 to 0.2; Preferably, the hydrogenation reaction is carried out at 130-210°C and 1-4 MPaG; More preferably, the feed space velocity of the hydrogenation reaction is 1 to 4 h -1 ; Further preferably, the hydrogenation reaction is carried out in a trickle bed hydrogenation reactor.

7. The recovery method according to any one of claims 1 to 6, characterized in that: The total loading amount of the metal components in the hydrogenation catalyst is 1 to 1.5 wt%; Preferably, the molar ratio of copper, nickel and zinc supported in the hydrogenation catalyst is 1:(0.2-0.5):(0.1-0.3).

8. The recovery method according to any one of claims 1 to 7, characterized in that: During the preparation process of the hydrogenation catalyst, the molecular sieve is first impregnated with an organic alkali solution to improve the pore structure of the molecular sieve, and then the precursor is dissolved in water to form a solution, and the pretreated molecular sieve is added thereto for impregnation and calcination to obtain a multi-level porous molecular sieve loaded with copper, nickel and zinc; Wherein, the precursor includes a copper-containing precursor, a nickel-containing precursor and a zinc-containing precursor; Preferably, the copper-containing precursor is selected from copper nitrate, the nickel-containing precursor is selected from nickel nitrate, and the zinc-containing precursor is selected from zinc acetate; More preferably, the molecular sieve is selected from SBA type molecular sieve or MCM type molecular sieve, preferably SBA-15 molecular sieve.

9. The recycling method according to claim 8, characterized in that: The organic alkaline solution is selected from quaternary ammonium bases, preferably one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide and tetrapropylammonium hydroxide; Preferably, the concentration of the organic base solution is 0.1 to 0.3 M; More preferably, the volume mass ratio of the organic alkali solution to the molecular sieve is preferably 20 to 30 ml of alkali solution / g of molecular sieve, the temperature at which the organic alkali solution is impregnated with the molecular sieve is 60 to 80° C., and the treatment time is 1 to 4 hours, preferably 1.5 to 2.5 hours; Further preferably, the pretreated molecular sieve is added and then impregnated in a nitrogen atmosphere, the impregnation temperature is 50-80°C, preferably 65-75°C, the impregnation time is 15-20h, preferably 16-17h; the volume mass ratio of the aqueous solution formed by the precursor to the molecular sieve is 10-15ml alkali solution / g molecular sieve; Further preferably, the calcination is carried out in an air atmosphere, with the temperature rising from 30°C to 200°C at a heating rate of 10°C / min, maintained for 1 hour, and then rising to 450-600°C at 5°C / min, and maintained for 12-25 hours.

10. The recovery method according to any one of claims 1 to 9, characterized in that: After the hydrogenation reaction is completed, the reaction materials are removed from the residual hydrogen in the product through a gas-liquid separation tank, and the hydrogenation product is sent to a distillation tower for separation; Preferably, the distillation tower is a packed tower, and the number of theoretical plates of the distillation tower is 8 to 12, preferably 9 to 10; The absolute pressure at the top of the distillation tower is 35-60 kPa, preferably 40-50 kPa; the operating temperature at the top is 65-110°C, preferably 90-100°C; the bottom temperature is 150-200°C, preferably 160-180°C; and the reflux ratio is 1-20, preferably 2-4.

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