A method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester

Abstract

The invention discloses a method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester. The raw material undecylenic acid methyl ester is pressurized by a pump, and after heat exchange with a water phase coming out of the lower layer of a hydrolysis tower in a heat exchanger, the raw material undecylenic acid methyl ester enters a hydrolysis tower from the bottom of the hydrolysis tower; water and solid catalyst powder are slurried, pressurized by a slurry pump, and after heat exchange with undecylenic acid coming out of the top of the hydrolysis tower in a heat exchanger, the hydrolysis catalyst is pumped into the hydrolysis tower from the upper part of the hydrolysis tower; the undecylenic acid after heat exchange enters an undecylenic acid crude product storage tank, and after the undecylenic acid crude product storage tank is left to stand, the upper oil phase enters an undecylenic acid distillation tower for refining, and the lower water phase returns to a process water storage tank; the catalyst in the water phase in the process water storage tank is discharged from the bottom, reused after regeneration, the water phase enters a methanol distillation tower to separate methanol, and after reaction, the methanol is recovered and the process water is recycled.

Description

Technical Field

[0001] The invention belongs to the technical field of undecylenic acid preparation, and particularly relates to a method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester. Background Art

[0002] The chemical name of nylon 11 is polyundecancylamide (PA11 for short). Its chemical structure is H[NH(CH2)10CO]nOH. It is a long carbon chain soft nylon synthesized from castor oil. It is an important variety of polyamide engineering plastics. The production of nylon 11 mainly includes the production of 10-undecenoic acid, 11-aminoundecanoic acid, monomer polymerization and resin modification.

[0003] There are two main processes for producing 10-undecenoic acid from castor oil in China: one is the traditional lead bath cracking technology, which mixes methyl ricinoleate and water vapor and passes it into a high-temperature lead liquid for cracking. The lead liquid is easily volatilized with the cracking products, causing serious environmental pollution and easy to coke. The other is the castor oil direct cracking process, which preheats castor oil to 150-200℃ and superheated steam according to the ratio, enters the tower cracking furnace, and is heated to 500-600℃ for thermal cracking to produce 10-undecenoic acid and heptanal products. This process is more difficult to control coking due to the high viscosity, poor fluidity and difficulty in gasification of castor oil.

[0004] Both of the above methods are based on thermal cracking technology. Since the thermal cracking temperature is too high, the ratio of side reactions such as polymerization and isomerization of double bonds, secondary cracking of products, and coking is very high, and it is difficult to increase the product yield.

[0005] Castor oil and methanol undergo ester exchange to generate ricinoleic acid methyl ester; ricinoleic acid methyl ester undergoes catalytic cracking to generate 10-undecenoic acid methyl ester and heptanal; 10-undecenoic acid methyl ester and heptanal are separated by vacuum distillation; 10-undecenoic acid methyl ester is saponified and acidified to obtain 10-undecenoic acid. In this method, undecenoic acid is prepared from undecenoic acid methyl ester by saponification and acidification, and a large amount of strong acids and bases such as sodium hydroxide and sulfuric acid are used, which increases the difficulty of sewage treatment, and the generated solid salts are difficult to handle, resulting in waste of resources and increased costs.

[0006] At present, the known oil hydrolysis methods include atmospheric pressure catalytic hydrolysis method and catalytic or non-catalytic medium pressure hydrolysis method. Atmospheric pressure catalytic hydrolysis method uses an acidic catalyst under atmospheric pressure, adds fresh water or low-concentration glycerol wastewater, and uses direct steam graded cooking to hydrolyze oil. The catalysts used in this method are usually sulfur and sulfuric acid. The disadvantages of atmospheric pressure hydrolysis method are that due to a very small amount of sulfation or sulfonation, the color of the fatty acids produced by hydrolysis is deepened, the steam consumption is large, the hydrolysis reaction time is long, the degree of hydrolysis is low, the glycerol content in the wastewater is low, and the cost of glycerol recovery is increased. At the same time, it contains sulfuric acid and sulfonic acid, which is highly corrosive to equipment.

[0007] The medium-pressure non-catalytic hydrolysis method relies on controlling a certain pressure, temperature, water addition amount and hydrolysis time to hydrolyze the oil; the medium-pressure catalytic hydrolysis method requires not only certain pressure, temperature, water addition and other conditions, but also requires the addition of a certain amount of catalyst to increase the solubility of water in the oil phase during the reaction, increase the reaction rate, and ensure a certain degree of hydrolysis. This method has a relatively long production cycle, large equipment investment, and a relatively low degree of hydrolysis.

[0008] Since methyl undecylenate is shorter than the general oil carbon chain, side reactions are prone to occur at higher temperatures and pressures, resulting in a decrease in the yield of undecylenic acid. When the temperature and pressure are low, the reaction speed is slow, the time consumption is long, and the energy consumption is high. At the same time, the long reaction time also leads to the occurrence of side reactions. The current public undecylenic acid production mainstream process is saponification acidification, which, in addition to the increased acid-base reagent consumption, produces a large amount of saline wastewater, and the waste salt produced after the wastewater treatment is also difficult to handle. Therefore, the development of new processes for economic and environmental protection is imminent. Summary of the invention

[0009] The purpose of the present invention is to solve the problems of large acid and alkali consumption in the existing saponification acidification method for producing undecylenic acid, and the generation of wastewater and waste residue that are difficult to treat, as well as the problem of low selectivity in the process of producing undecylenic acid by the traditional high-temperature hydrolysis method, and to provide a method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester, which reduces energy consumption and improves the yield and selectivity of undecylenic acid.

[0010] The technical solution adopted by the present invention is a method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester, comprising the following steps:

[0011] The raw material methyl undecylenate is pressurized by a pump, and after heat exchange with the water phase (the water phase includes water, catalyst and methanol) coming out of the lower layer of the hydrolysis tower in a heat exchanger, the methyl undecylenate enters the hydrolysis tower from the bottom of the hydrolysis tower; the water phase after heat exchange enters the process water storage tank;

[0012] After the water and solid catalyst powder are slurried, they are pressurized by a slurry pump and heat-exchanged with the undecylenic acid coming out of the top of the hydrolysis tower in a heat exchanger, and then the hydrolysis catalyst is pumped into the hydrolysis tower from the upper part of the hydrolysis tower; the undecylenic acid after heat exchange enters the undecylenic acid crude product storage tank, and after the undecylenic acid crude product storage tank is left to stand, the upper oil phase enters the undecylenic acid distillation tower for refining, and the lower water phase returns to the process water storage tank;

[0013] The catalyst in the water phase in the process water storage tank is discharged from the bottom and reused after regeneration. The water phase enters the methanol distillation tower to separate methanol, and the process water is recycled.

[0014] Furthermore, the reaction temperature in the hydrolysis tower is 120-200°C.

[0015] Furthermore, during the entire reaction process, the pressure in the hydrolysis tower is 0.2-1.5 MPa.

[0016] Furthermore, the mass ratio of the raw material methyl undecylenate to water (water for dissolving the solid catalyst powder) is 1:0.5-3.

[0017] Furthermore, the hydrolysis tower has four layers of bubble tower plates from top to bottom, an annular water distributor and a corresponding water inlet are installed above the topmost tower plate, an annular grease distributor and a corresponding grease inlet are installed below the bottommost tower plate, and a steam distributor and a corresponding steam inlet are installed at the bottom of each tower plate.

[0018] Furthermore, the solid catalyst powder is added in an amount of 0.5-2% of the mass of the raw material methyl undecylenate.

[0019] Furthermore, the carrier of the solid catalyst powder is an Al-Ce-Zr composite metal oxide, the carrier is modified by Ti-Si to obtain a modified carrier, the catalyst active components are Mg and Sn; the molar ratio of Al, Zr and Ce is 40-60:20-30:3-5.

[0020] Furthermore, the Ti-Si accounts for 3-10% of the carrier mass, and the TiO 2 and SiO 2 The mass ratio is 1:5~8.

[0021] Furthermore, the method for preparing the solid catalyst powder comprises the following steps:

[0022] 1) Dissolve the precursors of Al, Ce and Zr in deionized water and add the precipitant Na 2 CO 3 or NaHCO 3 , and then aging, filtering, washing, drying at 60-120°C for 8-12h, and calcining at 350-650°C for 3-6h to obtain a carrier;

[0023] 2) Add titanium sulfate and silica sol to the nitric acid solution, add urea, polyethylene glycol and ethanolamine while stirring, stir evenly, and age for 6 to 24 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:5-8;

[0024] 3) immersing the carrier obtained in step 1) into the Ti-Si composite sol obtained in step 2), drying at 60-120° C. for 8-12 h, and calcining at 350-650° C. for 3-6 h to obtain a Ti-Si modified carrier;

[0025] 4) preparing a mixed solution of Mg salt and Sn salt, immersing the Ti-Si modified carrier prepared in step 3) in the mixed solution for 100 to 240 minutes, drying at 80 to 120° C. for 8 to 12 hours, and calcining at 350 to 650° C. for 3 to 6 hours to obtain a solid catalyst powder.

[0026] Furthermore, after use, the solid catalyst powder is filtered and precipitated, then added to a 5% by mass ammonia solution, the pH is controlled at 10-14, stirred at room temperature for 2-4 hours, filtered and washed with water, dried at 80-150°C for 5-12 hours, and calcined at 350-650°C for 1-3 hours to obtain a regenerated catalyst.

[0027] Compared with the traditional technology, the present invention has the following advantages:

[0028] 1) With respect to the traditional saponification acidification method for hydrolyzing undecylenic acid methyl ester to prepare undecylenic acid, the present invention adopts a medium-low temperature catalytic hydrolysis method, shortens the process flow, and greatly reduces the discharge of wastewater and waste residue; avoids the problems of excessive addition of acid and alkali, high sewage treatment cost, and poor quality of the waste sodium sulfate produced in the saponification acidification method, which can only be treated as solid waste.

[0029] 2) The present invention adopts a medium-low temperature catalytic hydrolysis method. Compared with the traditional medium-pressure and high-pressure oil hydrolysis method, the reaction pressure and temperature are significantly reduced, the energy consumption is reduced, the occurrence of side reactions under high temperature and high pressure is reduced, the selectivity and yield of undecylenic acid are high, and the catalyst can be reused.

[0030] 3) In view of the problems existing in traditional oil hydrolysis catalysts, the present invention uses Ce-modified Al-Zr composite oxide as a carrier, and the composite oxide modification promotes the distribution of acid-base sites on the carrier surface, and improves hydrothermal stability and structural stability. Furthermore, the present invention uses Ti to compound Si and is used for carrier modification, which is more helpful to improve the hydrothermal stability of the catalyst. In the active component, the introduction of Sn increases the hydrothermal stability of Mg, helps the distribution of acid-base sites on the catalyst surface, adjusts the acid-base strength, and the loaded active component catalyzes the hydrolysis of undecylenic acid methyl ester with high activity. At a relatively low temperature and pressure, undecylenic acid methyl ester is hydrolyzed to generate undecylenic acid. Compared with no addition of catalyst, the hydrolysis temperature is low, the efficiency is high, the hydrolysis conversion rate of undecylenic acid methyl ester can reach more than 99%, and the yield of undecylenic acid can reach more than 98%.

[0031] 4) In the traditional preparation of ricinoleic acid by hydrolysis of castor oil, the added catalyst zinc oxide is discarded after one use; the catalyst used in the present invention can be restored to activity after simple alkali washing and roasting. After three uses, the catalyst activity is still maintained above 95%, which significantly reduces the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The present invention is a flow chart of the method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester. DETAILED DESCRIPTION

[0033] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0034] Example 1

[0035] like Figure 1 As shown, the raw material methyl undecylenate is pressurized by pump c, and after heat exchange with the aqueous phase (the aqueous phase includes water, catalyst and methanol) coming out of the lower layer of hydrolysis tower e in heat exchanger d, the raw material methyl undecylenate enters hydrolysis tower e from the bottom of hydrolysis tower e, and the aqueous phase after heat exchange enters process water storage tank g; water and solid catalyst powder are slurried and pressurized by slurry pump a, and after heat exchange with undecylenic acid coming out of the top of hydrolysis tower e in heat exchanger b, they are pumped into hydrolysis tower e from the upper part of hydrolysis tower e, and the liquid oil in the ascending process and the liquid water in the descending process are in countercurrent contact in hydrolysis tower e to cause hydrolysis reaction, and the undecylenic acid after heat exchange enters undecylenic acid crude product storage tank f, and after the crude undecylenic acid storage tank f is left to stand, the upper oil phase enters undecylenic acid distillation tower h for refining, and the lower aqueous phase returns to process water storage tank g; the catalyst in the aqueous phase in process water storage tank g is discharged from the bottom, and is reused after drying and roasting, and the aqueous phase enters methanol distillation tower i to separate methanol.

[0036] Among them, the mass ratio of raw material methyl undecylenate to water (water for dissolving solid catalyst powder) is 1:1, and the amount of solid catalyst powder added is 1% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 150°C. During the whole reaction process, the pressure in hydrolysis tower e is 0.47MPa.

[0037] The hydrolysis tower has four layers of bubble trays from top to bottom. An annular water distributor and a corresponding water inlet are installed above the top tray, an annular grease distributor and a corresponding grease inlet are installed below the bottom tray, and a steam distributor and a corresponding steam inlet are installed at the bottom of each tray.

[0038] Preparation of solid catalyst powder:

[0039] Preparation of vector:

[0040] 1) The carrier was prepared by coprecipitation method. 1L of a mixed solution of 0.4mol / L aluminum nitrate, 0.2mol / L zirconium nitrate and 0.03mol / L cerium nitrate was measured, and 0.2mol / L sodium carbonate solution was added dropwise at 80°C while stirring. The pH value of the solution was maintained at 8, and the stirring was continued for 8h. The solution was aged for 12h, and then filtered. The precipitate was washed with deionized water until it became neutral. The filter cake was dried at 110°C for 10h and calcined at 550°C for 5h to obtain the carrier. The molar ratio of Al, Zr and Ce was 40:20:3.

[0041] 2) 5 g of titanium sulfate and 50 g of 20% silica sol were added to 180 mL of 5% dilute nitric acid, and 3 g of urea, 3 g of polyethylene glycol and 3 g of ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:6.

[0042] 3) 50 g of the carrier obtained in step 1) was immersed in 50 ml of the Ti-Si composite sol obtained in step 2), and after stirring, it was dried at 110° C. for 12 h and calcined at 550° C. for 5 h to obtain a modified carrier, wherein the amount of Ti-Si added was 6% of the carrier mass;

[0043] Preparation of catalyst: Prepare 60mL of a mixed solution of 2.08mol / L magnesium nitrate and 0.11mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 110℃ for 12h, and calcine at 550℃ for 4h to obtain a solid catalyst powder. 2 They account for 10% and 2% of the catalyst mass respectively.

[0044] Reaction results: undecylenic acid methyl ester conversion rate was 99.87%, undecylenic acid selectivity was 99.15%, and undecylenic acid yield was 99.02%.

[0045] The mass ratio of raw material methyl undecylenate to water is 1:1, and the amount of solid catalyst powder added is 1.5% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 160°C. During the whole reaction process, the pressure in hydrolysis tower e is 0.6MPa.

[0046] Preparation of vector:

[0047] 1) The carrier was prepared by coprecipitation method. 1L of a mixed solution of 0.5mol / L aluminum nitrate, 0.2mol / L zirconium nitrate and 0.05mol / L cerium nitrate was measured, and 0.2mol / L sodium carbonate solution was added dropwise at 80°C while stirring. The pH value of the solution was maintained at 8, and the stirring was continued for 8h. The solution was aged for 12h, and then filtered. The precipitate was washed with deionized water until it became neutral. The filter cake was dried at 110°C for 10h and calcined at 550°C for 5h to obtain the carrier. The molar ratio of Al, Zr and Ce was 50:20:5.

[0048] 2) 4.3 g titanium sulfate and 50 g silica sol with a mass concentration of 20% were added to 180 mL of 5% dilute nitric acid, and 3 g urea, 3 g polyethylene glycol and 3 g ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:7.

[0049] 3) 50 g of the carrier obtained in step 1) was immersed in 50 ml of the Ti-Si composite sol obtained in step 2), and after stirring, it was dried at 120° C. for 8 h and calcined at 650° C. for 5 h to obtain a modified carrier, wherein the amount of Ti-Si added was 6% of the carrier mass;

[0050] Preparation of catalyst: Prepare 60mL of a mixed solution of 2.5mol / L magnesium nitrate and 0.1671mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 80℃ for 12h, and calcine at 550℃ for 5h to obtain a solid catalyst powder. 2 They account for 12% and 3% of the catalyst mass respectively.

[0051] Reaction results: undecylenic acid methyl ester conversion rate was 99.77%, undecylenic acid selectivity was 99.11%, and undecylenic acid yield was 98.88%.

[0052] Example 3

[0053] The mass ratio of raw material methyl undecylenate to water is 1:2, and the amount of solid catalyst powder added is 0.5% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 140°C. During the whole reaction process, the pressure in hydrolysis tower e is 0.36MPa.

[0054] Preparation of vector:

[0055] 1) The carrier was prepared by coprecipitation method. 1L of a mixed solution of 0.5mol / L aluminum nitrate, 0.3mol / L zirconium nitrate and 0.03mol / L cerium nitrate was measured, and 0.2mol / L sodium carbonate solution was added dropwise at 80°C while stirring. The pH value of the solution was maintained at 8, and the stirring was continued for 8h. The solution was aged for 12h, and then filtered by suction. The precipitate was washed with deionized water until it became neutral. The filter cake was dried at 110°C for 12h and calcined at 550°C for 4h to obtain the carrier. The molar ratio of Al, Zr and Ce was 50:30:3.

[0056] 2) 1.88 g titanium sulfate and 25 g silica sol with a mass concentration of 20% were added to 90 mL of 5% dilute nitric acid, and 1.5 g urea, 1.5 g polyethylene glycol and 1.5 g ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:8.

[0057] 3) Take 50g of the carrier obtained in step 1) and immerse it in 50ml of the Ti-Si composite sol obtained in step 2), stir it, dry it at 110°C for 12h, and calcine it at 550°C for 5h to obtain a modified carrier. The amount of Ti-Si added is 3% of the carrier mass.

[0058] Preparation of catalyst: Prepare 60mL of a mixed solution of 1.67mol / L magnesium nitrate and 0.111mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 110℃ for 12h, and calcine at 550℃ for 4h to obtain a solid catalyst powder. 2 They account for 8% and 2% of the catalyst mass respectively.

[0059] Reaction results: undecylenic acid methyl ester conversion rate was 99.68%, undecylenic acid selectivity was 99.05%, and undecylenic acid yield was 98.73%.

[0060] Example 4

[0061] The mass ratio of raw material methyl undecylenate to water is 1:0.5, and the amount of solid catalyst powder added is 1% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 150°C. During the whole reaction process, the pressure in hydrolysis tower e is 0.47MPa.

[0062] Preparation of vector:

[0063] 1) The carrier was prepared by coprecipitation method. 1L of a mixed solution of 0.6mol / L aluminum nitrate, 0.2mol / L zirconium nitrate and 0.05mol / L cerium nitrate was measured, and 0.2mol / L sodium carbonate solution was added dropwise at 80°C while stirring. The pH value of the solution was maintained at 8, and the stirring was continued for 8h. The solution was aged for 12h, and then filtered by suction. The precipitate was washed with deionized water until it became neutral. The filter cake was dried at 110°C for 10h and calcined at 550°C for 5h to obtain the carrier. The molar ratio of Al, Zr and Ce was 60:20:5.

[0064] 2) 6 g titanium sulfate and 50 g silica sol with a mass concentration of 20% were added to 180 mL of 5% dilute nitric acid, and 3 g urea, 3 g polyethylene glycol and 3 g ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:5.

[0065] 3) Take 50g of the carrier obtained in step 1) and immerse it in 50ml of the Ti-Si composite sol obtained in step 2), stir it, dry it at 110°C for 12h, and calcine it at 550°C for 5h to obtain a modified carrier. The amount of Ti-Si added is 5% of the carrier mass.

[0066] Preparation of catalyst: Prepare 60mL of a mixed solution of 3.13mol / L magnesium nitrate and 0.0561mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 110℃ for 12h, and calcine at 550℃ for 4h to obtain a solid catalyst powder. 2 They account for 15% and 1% of the catalyst mass respectively.

[0067] Reaction results: undecylenic acid methyl ester conversion rate was 99.67%, undecylenic acid selectivity was 98.86%, and undecylenic acid yield was 98.53%.

[0068] Example 5

[0069] The mass ratio of raw material methyl undecylenate to water is 1:0.5, and the amount of solid catalyst powder added is 0.5% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 160°C. During the whole reaction process, the pressure in hydrolysis tower e is 0.6MPa.

[0070] Preparation of vector:

[0071] 1) The carrier was prepared by coprecipitation method. 1L of a mixed solution of 0.5mol / L aluminum nitrate, 0.3mol / L zirconium nitrate and 0.03mol / L cerium nitrate was measured, and 0.2mol / L sodium carbonate solution was added dropwise at 80°C while stirring. The pH value of the solution was maintained at 8, and the stirring was continued for 8h. The mixture was aged for 12h, and then filtered. The precipitate was washed with deionized water until it became neutral. The filter cake was dried at 110°C for 10h and calcined at 650°C for 6h to obtain the carrier. The molar ratio of Al, Zr and Ce was 50:30:3.

[0072] 2) 4.3 g titanium sulfate and 50 g silica sol with a mass concentration of 20% were added to 180 mL of 5% dilute nitric acid, and 3 g urea, 3 g polyethylene glycol and 3 g ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:7.

[0073] 3) Take 50g of the carrier obtained in step 1) and immerse it in 50ml of the Ti-Si composite sol obtained in step 2), stir it, dry it at 120°C for 8h, and calcine it at 650°C for 5h to obtain a modified carrier. The amount of Ti-Si added is 7% of the carrier mass.

[0074] Preparation of catalyst: Prepare 60mL of a mixed solution of 2.08mol / L magnesium nitrate and 0.1671mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 110℃ for 12h, and calcine at 550℃ for 4h to obtain a solid catalyst powder. 2 They account for 10% and 3% of the catalyst mass respectively.

[0075] Reaction results: undecylenic acid methyl ester conversion rate was 99.25%, undecylenic acid selectivity was 98.65%, and undecylenic acid yield was 97.91%.

[0076] Example 6

[0077] The mass ratio of raw material methyl undecylenate to water is 1:2, and the amount of solid catalyst powder added is 0.5% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 170°C. During the whole reaction process, the pressure in hydrolysis tower e is 0.79MPa.

[0078] Preparation of vector:

[0079] 1) The carrier is prepared by coprecipitation method. 1L of a mixed solution of 0.4mol / L aluminum nitrate, 0.3mol / L zirconium nitrate and 0.04mol / L cerium nitrate is measured, and 0.2mol / L sodium bicarbonate solution is added dropwise at 80°C while stirring, and the pH value of the solution is maintained at 7-8. The mixture is stirred for 8h, aged for 12h, and then filtered by suction. The precipitate is washed with deionized water until it becomes neutral. The filter cake is dried at 60°C for 12h and calcined at 350°C for 6h to obtain the carrier. The molar ratio of Al, Zr and Ce is 40:30:4.

[0080] 2) 5 g of titanium sulfate and 50 g of 20% silica sol were added to 180 mL of 5% dilute nitric acid, and 3 g of urea, 3 g of polyethylene glycol and 3 g of ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:6.

[0081] 3) Take 50g of the carrier obtained in step 1) and immerse it in 65ml of the Ti-Si composite sol obtained in step 2), stir it, dry it at 110°C for 12h, and calcine it at 550°C for 5h to obtain a modified carrier. The amount of Ti-Si added is 8% of the carrier mass.

[0082] Preparation of catalyst: Prepare 60mL of a mixed solution of 2.92mol / L magnesium nitrate and 0.111mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 100℃ for 8h, and calcine at 650℃ for 3h to obtain a solid catalyst powder. 2 They account for 14% and 2% of the catalyst mass respectively.

[0083] Reaction results: undecylenic acid methyl ester conversion rate was 99.17%, undecylenic acid selectivity was 98.57%, and undecylenic acid yield was 97.75%.

[0084] Example 7

[0085] The mass ratio of raw material methyl undecylenate to water is 1:3, and the amount of solid catalyst powder added is 2% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 180°C. During the whole reaction process, the pressure in hydrolysis tower e is 1MPa.

[0086] Preparation of vector:

[0087] 1) The carrier is prepared by coprecipitation method. 1L of a mixed solution of 0.6mol / L aluminum nitrate, 0.3mol / L zirconium nitrate and 0.05mol / L cerium nitrate is measured, and 0.2mol / L sodium carbonate solution is added dropwise at 80°C while stirring, and the pH value of the solution is maintained at 7-8. The mixture is stirred for 8h, aged for 12h, and then filtered by suction. The precipitate is washed with deionized water until it becomes neutral. The filter cake is dried at 60°C for 12h and calcined at 450°C for 3h to obtain the carrier. The molar ratio of Al, Zr and Ce is 60:30:5.

[0088] 2) 7.5 g titanium sulfate and 100 g silica sol with a mass concentration of 20% were added to 360 mL of 5% dilute nitric acid, and 6 g urea, 6 g polyethylene glycol and 6 g ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:8.

[0089] 3) Take 50g of the carrier obtained in step 1) and immerse it in 50ml of the Ti-Si composite sol obtained in step 2), stir it, dry it at 120°C for 8h, and calcine it at 550°C for 6h to obtain a modified carrier. The amount of Ti-Si added is 10% of the carrier mass.

[0090] Preparation of catalyst: Prepare 60mL of a mixed solution of 1.25mol / L magnesium nitrate and 0.056 1mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 120℃ for 8h, and calcine at 650℃ for 4h to obtain a solid catalyst powder. 2 They account for 6% and 1% of the catalyst mass respectively.

[0091] Reaction results: undecylenic acid methyl ester conversion rate was 99.48%, undecylenic acid selectivity was 98.52%, and undecylenic acid yield was 98.01%.

[0092] Example 8

[0093] The mass ratio of raw material methyl undecylenate to water (water for dissolving solid catalyst powder) is 1:3, and the amount of solid catalyst powder added is 0.5% of the mass of raw material methyl undecylenate; the air intake of high-pressure steam in hydrolysis tower e is controlled so that the reaction temperature in hydrolysis tower e is 200°C. During the whole reaction process, the pressure in hydrolysis tower e is 1.5MPa.

[0094] Preparation of vector:

[0095] 1) The carrier is prepared by coprecipitation method. 1L of a mixed solution of 0.4mol / L aluminum nitrate, 0.2mol / L zirconium nitrate and 0.05mol / L cerium nitrate is measured, and 0.2mol / L sodium bicarbonate solution is added dropwise at 80°C while stirring, and the pH value of the solution is maintained at 7-8. The mixture is stirred for 8h, aged for 12h, and then filtered by suction. The precipitate is washed with deionized water until it becomes neutral. The filter cake is dried at 60°C for 12h and calcined at 650°C for 5h to obtain the carrier. The molar ratio of Al, Zr and Ce is 40:20:5.

[0096] 2) 6 g titanium sulfate and 50 g silica sol with a mass concentration of 20% were added to 180 mL of 5% dilute nitric acid, and 3 g urea, 3 g polyethylene glycol and 3 g ethanolamine were added during stirring. The mixture was aged for 12 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:5.

[0097] 3) Take 50g of the carrier obtained in step 1) and immerse it in 50ml of the Ti-Si composite sol obtained in step 2), stir it, dry it at 80°C for 12h, and calcine it at 650°C for 5h to obtain a modified carrier. The amount of Ti-Si added is 6% of the carrier mass.

[0098] Preparation of catalyst: Prepare 60mL of a mixed solution of 1.04mol / L magnesium nitrate and 0.0561mol / L tin nitrate, immerse 50g of the modified carrier in the mixed solution for 4h, dry at 110℃ for 12h, and calcine at 550℃ for 4h to obtain a solid catalyst powder. 2 They account for 5% and 1% of the catalyst mass respectively.

[0099] Reaction results: undecylenic acid methyl ester conversion rate was 99.26%, undecylenic acid selectivity was 98.38%, and undecylenic acid yield was 97.65%.

[0100] Comparative Example 1

[0101] No catalyst was added, and the other steps were the same as in Example 1.

[0102] Comparative Example 2

[0103] The catalyst in Example 1 was changed to zinc oxide, and the other components remained unchanged.

[0104] Comparative Example 3

[0105] The catalyst used was the catalyst regenerated after use in Example 1, and the rest was the same as in Example 1.

[0106] Comparative Example 4

[0107] The catalyst used was the catalyst dried after use in Example 1, and the rest was the same as in Example 1.

[0108] Comparative Example 5

[0109] The catalyst carrier used was not modified, and the rest was the same as in Example 1.

[0110] Table 1 Reaction data

[0111] Undecylenic acid methyl ester hydrolysis rate / % Undecylenic acid selectivity / % Undecylenic acid yield / % Example 1 99.87 99.15 99.02 Example 2 99.77 99.11 98.88 Example 3 99.68 99.05 98.73 Example 4 99.67 98.86 98.53 Example 5 99.25 98.65 97.91 Example 6 99.17 98.57 97.75 Example 7 99.48 98.52 98.01 Example 8 99.26 98.38 97.65 Comparative Example 1 65.38 98.83 64.62 Comparative Example 2 70.13 75.25 52.77 Comparative Example 3 99.78 99.03 98.81 Comparative Example 4 88.17 96.58 85.15 Comparative Example 5 99.72 99.01 98.73

[0112] Table 2 Catalyst regeneration data

[0113]

[0114] The results of Examples 1-8 in Table 1 show that the method of the present invention has the advantages of high hydrolysis rate of methyl undecylenate, high selectivity of undecylenate and high yield, and the hydrolysis rate of methyl undecylenate can reach more than 99%, the selectivity of undecylenate can reach 98.38-99.15%, and the yield of undecylenate can reach 97.65-99.02%. The result of Comparative Example 1 shows that when no catalyst is used, the hydrolysis rate of methyl undecylenate significantly decreases, the selectivity of undecylenate also slightly decreases, and the yield of undecylenate is only 64.62%. The result of Comparative Example 2 shows that, using zinc oxide as a hydrolysis catalyst, although the hydrolysis rate is slightly increased than when no catalyst is used, the selectivity of undecylenate significantly decreases, which is only 75.25%, and the yield of undecylenate is 52.77%. The result of Comparative Example 3 shows that after the catalyst of the present invention is regenerated by the method of the present invention, the catalytic activity is almost completely restored. The result of Comparative Example 4 shows that after the catalyst of the present invention is simply dried, the catalytic activity can be partially restored. This shows that the regeneration method of the present invention has a good regeneration effect. The results of comparative example 5 show that when the catalyst carrier is not modified, the catalytic activity is equivalent to that after modification. The regeneration results of the catalysts of Example 1 and Comparative Example 5 in Table 2 show that after three regenerations, the yield of undecylenic acid in Example 1 is reduced from 99.02% to 97.01%, indicating that the catalyst regeneration effect is good and can be used repeatedly. After three regenerations, the yield of undecylenic acid in Comparative Example 5 is reduced from 98.73% to 89.04%. It shows that the carrier modification method described in the present invention has a significant improvement effect on the regeneration performance of the catalyst, so that the catalyst can be repeatedly used after simple regeneration, reducing production costs.

Claims

1. A method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester, It is characterized in that The following steps are involved: The raw material methyl undecylenate is pressurized by pump (c), and after heat exchange with the water phase coming out of the lower layer of the hydrolysis tower (e), the methyl undecylenate enters the hydrolysis tower (e) from the bottom of the hydrolysis tower (e); the water phase after heat exchange enters the process water storage tank (g); After the water and the solid catalyst powder are slurried, they are pressurized by a slurry pump (a) and heat exchanged with the undecylenic acid coming out of the top of the hydrolysis tower (e), and then pumped into the hydrolysis tower (e) from the upper part of the hydrolysis tower (e); the undecylenic acid after the heat exchange enters the undecylenic acid crude product storage tank (f), and after the undecylenic acid crude product storage tank (f) is washed with water, the upper oil phase enters the undecylenic acid distillation tower (h) for refining, and the lower water phase returns to the process water storage tank (g); The catalyst in the water phase in the process water storage tank (g) is discharged from the bottom and reused after regeneration. The water phase enters the methanol distillation tower (i) to separate methanol, and the process water is recycled; The carrier of the solid catalyst powder is an Al-Ce-Zr composite metal oxide, the carrier is modified by Ti-Si to obtain a modified carrier, the catalyst active components are Mg and Sn; the molar ratio of Al, Zr and Ce is 40-60:20-30:3-5; the preparation method of the solid catalyst powder comprises the following steps: 1) Dissolve the precursors of Al, Ce and Zr in deionized water and add the precipitant Na 2 CO 3 or NaHCO 3 , and then aging, filtering, washing, drying at 60-120°C for 8-12h, and calcining at 350-650°C for 3-6h to obtain a carrier; 2) Add titanium sulfate and silica sol to the nitric acid solution, add urea, polyethylene glycol and ethanolamine while stirring, stir evenly, and age for 6 to 24 hours to obtain a stable Ti-Si composite sol. 2 and SiO 2 The mass ratio is 1:5-8; 3) immersing the carrier obtained in step 1) into the Ti-Si composite sol obtained in step 2), drying at 60-120° C. for 8-12 h, and calcining at 350-650° C. for 3-6 h to obtain a Ti-Si modified carrier; 4) preparing a mixed solution of Mg salt and Sn salt, immersing the Ti-Si modified carrier prepared in step 3) in the mixed solution for 100 to 240 minutes, drying at 80 to 120° C. for 8 to 12 hours, and calcining at 350 to 650° C. for 3 to 6 hours to obtain a solid catalyst powder.

2. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, It is characterized in that The reaction temperature in the hydrolysis tower (e) is 120-200°C.

3. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, It is characterized in that The pressure in the hydrolysis tower (e) is 0.2-1.5 MPa.

4. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, It is characterized in that The mass ratio of the raw material methyl undecylenate to water is 1:0.5-3.

5. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, It is characterized in that The hydrolysis tower has four layers of bubble trays from top to bottom, an annular water distributor and a corresponding water inlet are installed above the top tray, an annular grease distributor and a corresponding grease inlet are installed below the bottom tray, and a steam distributor and a corresponding steam inlet are installed at the bottom of each tray.

6. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, It is characterized in that The added amount of the solid catalyst powder is 0.5-2% of the mass of the raw material methyl undecylenate.

7. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, Features: The Ti-Si accounts for 3-10% of the carrier mass, and the TiO 2 and SiO 2 The mass ratio is 1:5~8.

8. The method for preparing undecylenic acid by hydrolyzing undecylenic acid methyl ester according to claim 1, Features: After use, the solid catalyst powder is filtered and precipitated, then added into a 5% by mass ammonia solution, stirred at room temperature for 2 to 4 hours, filtered, washed with water, dried at 80 to 150° C. for 5 to 12 hours, and calcined at 350 to 650° C. for 1 to 3 hours to obtain a regenerated catalyst.

Images