CN116063171A - A method for preparing undecylenic acid by catalytic hydrolysis at medium and low temperature - Google Patents

Abstract

The invention discloses a method for preparing undecylenic acid by catalytic hydrolysis at a medium and low temperature. Methyl undecylenate, water and a hydrolysis catalyst enter the hydrolysis reaction kettle from the top inlet of the hydrolysis reaction kettle, and methanol vapor passes through the hydrolysis reaction kettle after hydrolysis. The top outlet enters the condenser. After condensation, the methanol enters the methanol recovery tank. The oil phase on the upper layer of the methanol recovery tank returns to the hydrolysis reaction kettle after being pressurized by the pump; Add water to wash undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower for refining; the lower layer water in the precipitation kettle and the hydrolysis catalyst enter the process water storage tank together with the lower layer water in the hydrolysis reaction kettle. The catalyst in the lower layer of the process water storage tank is discharged and regenerated for reuse. After the reaction, the methanol is recovered and the process water is recycled. The medium and low temperature catalytic hydrolysis method shortens the process flow, increases the conversion rate of undecylenic acid methyl ester and the yield of undecylenic acid, reduces energy consumption, and greatly reduces the discharge of waste water and waste residue; avoids the acidification in the saponification acidification method The problem of excessive addition of alkali, high cost of sewage and waste residue treatment.

Description

A method for preparing undecylenic acid by catalytic hydrolysis at medium and low temperature

technical field

The invention belongs to the technical field of preparing undecylenic acid, in particular to a method for preparing undecylenic acid by catalytic hydrolysis at a medium and low temperature.

Background technique

The chemical name of nylon 11 is polyundecylactam, the English name is Polyundecancylamide (abbreviated as PA11), and the chemical structure formula is H[NH(CH2)10CO]nOH. It is a long carbon chain soft nylon synthesized from castor oil. An important variety of amide engineering plastics. The production of nylon 11 mainly includes the production of 10-undecylenic acid, 11-aminoundecylic acid, monomer polymerization and resin modification.

There are two main processes for producing 10-undecylenic acid from castor oil in China: one is the traditional lead bath cracking technology, which mixes methyl ricinoleate and water vapor into high-temperature lead liquid for cracking, and the lead liquid is easy to As the pyrolysis products volatilize, it will cause serious environmental pollution, and it is easy to coke. The other is the direct cracking process of castor oil, in which the castor oil is preheated to 150-200°C and superheated steam according to the ratio, enters the tower cracking furnace, and is heated to 500-600°C for thermal cracking, and the output is 10-11 Acenoic acid and heptanal products. In this process, due to the high viscosity of castor oil, poor fluidity and difficulty in gasification, coking is more difficult to control.

The above two methods are all based on thermal cracking process. Because 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 large, and the product yield is difficult to increase.

Transesterification of castor oil and methanol to produce ricinoleic acid methyl ester; catalytic cracking of ricinoleic acid methyl ester to produce 10-undecylenic acid methyl ester and heptanal; vacuum distillation to separate 10-undecylenic acid methyl ester and heptanal ; 10-undecylenic acid methyl ester was saponified and acidified to obtain 10-undecylenic acid. In this method, undecylenic acid is prepared from undecylenic acid methyl ester by saponification acidification method, using a large amount of strong acid and strong alkali such as sodium hydroxide and sulfuric acid, which increases the difficulty of sewage treatment, and the solid salts generated are difficult to handle , resulting in a waste of resources and an increase in costs.

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

The medium-pressure non-catalytic hydrolysis method relies on controlling a certain pressure, temperature, water addition and hydrolysis time to hydrolyze the oil; the medium-pressure catalytic hydrolysis method needs to have certain pressure, temperature, water addition and other conditions, and also needs to add a certain amount Catalysts are used to increase the solubility of water in the oil phase during the reaction, increase the rate of the reaction, and at the same time ensure a certain degree of hydrolysis. This method has relatively long production cycle, large equipment investment and relatively low degree of hydrolysis.

Since methyl undecylenate has a shorter carbon chain than ordinary oils, 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 will also lead to the occurrence of side reactions.

Contents of the invention

The purpose of the present invention is to solve the problem that the existing saponification and acidification method produces undecylenic acid in the system of large acid and alkali consumption, and produces waste water and waste residues that are difficult to handle, and the traditional high-temperature hydrolysis method is used to produce undecylenic acid. The lower problem is to provide a method for preparing undecylenic acid by medium and low temperature catalytic hydrolysis with mild reaction conditions, energy saving and environmental protection, high selectivity of undecylenic acid and high yield.

The technical scheme adopted in the present invention is that the method for preparing undecylenic acid by medium and low temperature catalytic hydrolysis is as follows;

Methyl undecylenate, water and catalyst enter the hydrolysis reactor from the inlet of the top of the hydrolysis reactor. After hydrolysis, the methanol vapor enters the condenser through the outlet of the top of the hydrolysis reactor. After condensation, the methanol enters the methanol recovery tank, and the upper layer of the methanol recovery tank The phase returns to the hydrolysis reaction kettle after being pressurized by the pump, and the methanol and water in the lower layer of the methanol recovery tank enter the methanol rectification tower for separation;

The undecylenic acid in the upper layer of the hydrolysis reaction kettle is passed into the precipitation tank, and the undecylenic acid in the upper layer is added to the precipitation tank to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower for refining; the water and catalyst in the lower layer of the precipitation tank and the hydrolysis The water in the lower layer of the reaction kettle enters the process water storage tank together, the catalyst in the lower layer of the process water storage tank is discharged and recycled, and the reacted process water is recycled.

Further, the reaction temperature of the methyl undecylenate and water in the hydrolysis reactor is 120-200°C.

Further, during the whole reaction process, the pressure in the hydrolysis reactor is 0.2-1.5 MPa.

Further, the mass-number ratio of methyl undecylenate to water is: 1:0.5-4.

Further, the addition amount of the catalyst is 0.5-2% of the mass of methyl undecylenate.

Further, the catalyst is Al, Zr, La, Mg and Zn composite oxide carrier modified with Al-Si sol after roasting, and the molar ratio of Al, Zr, La, Mg and Zn is 80-100:40-60 :5～10: 40～60: 20～30.

Further, the preparation method of the catalyst is as follows: mixing the metal precursor salt of the composite oxide carrier and citric acid of the same amount to form a sol, then stirring at 50-80°C to form a gel, and then stirring at 80-120°C Drying at low temperature for 5-12 hours, calcining at 350-650°C for 3-8 hours, and cooling to room temperature to obtain a composite oxide carrier;

Immerse the composite oxide carrier in a sol containing Al and Si, stir and impregnate for 6-12 hours, filter, dry at 80-120°C for 5-12 hours, bake at 350-650°C for 3-8 hours, cool to room temperature, A hydrolysis catalyst was obtained.

Further, the Al-Si coating accounts for 5-8% of the mass of the catalyst, and the mass ratio of Al ₂ O ₃ to SiO ₂ is 1:5-8.

Further, after the catalyst is used, it is filtered and precipitated and added to a sodium carbonate solution with a mass fraction of 2%, stirred at room temperature for 2 to 4 hours, washed with an appropriate amount of water after filtration, and dried at 80 to 150°C for 5 to 12 hours. Roast at 350-650°C for 3-8 hours to obtain the regenerated catalyst.

Compared with conventional technology, the present invention has the following advantages:

1) Aiming at the saponification and acidification method used in the traditional hydrolysis of undecylenic acid methyl ester to prepare undecylenic acid, the present invention adopts the medium and low temperature catalytic hydrolysis method, which shortens the process flow and greatly reduces the discharge of waste water and waste residue; avoids the saponification and acidification method The problem of excessive addition of acid and alkali, high cost of sewage and waste salt treatment.

2) The present invention adopts an oxide catalyst. 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, and the selectivity and yield of undecylenic acid are high. , and the catalyst can be reused.

3) In the method of the present invention, the methanol produced by the hydrolysis of undecylenic acid methyl ester is removed in time, which helps the reaction to proceed forward, increases the conversion rate of undecylenic acid hydrolysis, reduces the reaction time, and is also conducive to the methanol produced by hydrolysis. Recycle. The production cost is reduced, and the recovery of by-products also brings certain economic benefits.

4) Aiming at the problems existing in the traditional oil hydrolysis catalyst, the present invention prepares the active component and the carrier component through the precipitation method in one step, which improves the stability of the catalyst, the introduction of Zr enriches the acid-base sites on the Al surface, and the introduction of La The hydrothermal stability of the carrier is improved, and the interaction between Zn and Mn contributes to the acid-base distribution of the catalyst and increases the alkali strength. At the same time, the one-step preparation enhances the interaction between the various components and improves the hydrothermal stability of the catalyst. Furthermore, the present invention uses Al to compound Si and use it for catalyst modification, which is more helpful to improve the hydrothermal and structural stability of the catalyst and increase the life of the catalyst. The prepared catalyst has high activity in catalyzing the hydrolysis of undecylenic acid methyl ester, and the undecylenic acid methyl ester is hydrolyzed to generate undecylenic acid under lower temperature and pressure. Compared with no catalyst added, the hydrolysis temperature is low and the efficiency is high, the hydrolysis conversion rate of undecylenic acid methyl ester can reach more than 99%, and the undecylenic acid yield can reach more than 98%.

5) In the preparation of ricinoleic acid by hydrolysis of traditional castor oil, the added catalyst zinc oxide is discarded after being used once. The invention provides a catalyst regeneration method. After the catalyst is used, its activity can be restored after simple alkali washing and roasting, and the activity of the catalyst remains above 95% after three times of application, which significantly reduces the production cost.

6) The present invention has low hydrolysis temperature, adopts hydrolysis reactor, low investment, flexible production, and low production cost.

Description of drawings

Fig. 1 is a schematic flow chart of the method for preparing undecylenic acid by catalytic hydrolysis at low temperature in the present invention.

Detailed ways

The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.

Example 1

As shown in Figure 1, methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, and the methanol vapor after hydrolysis enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol Enter the methanol recovery tank c, the upper oil phase of the methanol recovery tank c returns to the hydrolysis reaction kettle a after being pressurized by the pump, the methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; the mass ratio of oil to water is controlled during the reaction The ratio is 1:1, the amount of catalyst added accounts for 1.5% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 150°C, the pressure is controlled at 0.47MPa, and the stirring speed is controlled at 200rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.45mol/L aluminum nitrate, 0.25mol/L zirconium nitrate, 0.04mol/L lanthanum nitrate, 0.25mol/L magnesium nitrate and 0.125mol/L zinc chloride, add 214g citric acid, and stir well , to make a sol, then continue stirring at 60°C to form a gel, dry at 110°C for 12 hours, bake at 550°C for 4 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 45:25:2.5:25:12.5.

2) Add 7g of aluminum nitrate and 50g of 20% mass concentration silica sol to 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite sol , the mass ratio of Al ₂ O ₃ and SiO ₂ is 1:6.

3) Take 50g of the composite oxide carrier obtained in step 1) and immerse 50ml of the sol obtained in step 2), and after stirring, dry at 110°C for 12h and roast at 550°C for 5h to obtain a modified catalyst. 6%;

Reaction result: the conversion rate of undecylenic acid methyl ester is 99.79%, the selectivity of undecylenic acid is 99.22%, and the yield of undecylenic acid is 99.01%.

Example 2

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reaction kettle a. The methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:2, and the catalyst The amount added accounts for 1% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 160° C., the pressure is controlled at 0.6 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.4mol/L aluminum nitrate, 0.25mol/L zirconium nitrate, 0.025mol/L lanthanum nitrate, 0.3mol/L magnesium nitrate and 0.1mol/L zinc chloride, add 206g citric acid, and stir well , to make a sol, then continue stirring at 60°C to form a gel, dry at 110°C for 12 hours, bake at 450°C for 8 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 40:25:2.5:30:10.

2) Add 5g of aluminum nitrate and 50g of 20% mass concentration silica sol into 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite sol , the mass ratio of Al ₂ O ₃ and SiO ₂ is 1:7.

3) Take 50g of the composite oxide carrier obtained in step 1) and immerse 58ml of the sol obtained in step 2), and after stirring, dry at 110°C for 12h and roast at 450°C for 5h to obtain a hydrolysis catalyst. The amount of Al-Si added is 7% of the mass of the catalyst. %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 99.71%, the selectivity of undecylenic acid is 99.01%, and the yield of undecylenic acid is 98.72%.

Example 3

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reactor a. The methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:1, and the catalyst The amount added accounts for 1.5% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 160° C., the pressure is controlled at 0.6 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.5mol/L aluminum nitrate, 0.3mol/L zirconium nitrate, 0.05mol/L lanthanum nitrate, 0.2mol/L magnesium nitrate and 0.12mol/L zinc chloride, add 225g citric acid, and stir well , to make a sol, then continue to stir at 60°C to form a gel, dry at 100°C for 10 hours, bake at 650°C for 3 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 50:30:5:20:12.

2) Add 7g of aluminum nitrate and 50g of 20% mass concentration silica sol to 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite sol , the mass ratio of Al ₂ O ₃ and SiO ₂ is 1:6.

3) Take 50 g of the composite oxide carrier obtained in step 1) and immerse 50 ml of the sol obtained in step 2), and after stirring, dry at 110° C. for 12 hours and roast at 650° C. for 3 hours to obtain a hydrolysis catalyst. The amount of Al-Si added is 6% of the mass of the catalyst. %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 99.72%, the selectivity of undecylenic acid is 99.08%, and the yield of undecylenic acid is 98.80%.

Example 4

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reaction kettle a, the methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:0.5, and the catalyst The amount added accounts for 2% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 170° C., the pressure is controlled at 0.79 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.4mol/L aluminum nitrate, 0.2mol/L zirconium nitrate, 0.025mol/L lanthanum nitrate, 0.2mol/L magnesium nitrate and 0.1mol/L zinc chloride, add 178g citric acid, and stir well , to make a sol, then continue stirring at 60°C to form a gel, dry at 80°C for 12 hours, bake at 550°C for 4 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 40:20:2.5:20:10.

2) Add 8.4g of aluminum nitrate and 50g of 20% mass concentration silica sol to 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite The mass ratio _of sol, _Al2O3 and _SiO2 is 1:5.

3) Take 50g of the composite oxide carrier obtained in step 1) and immerse 42ml of the sol obtained in step 2), and after stirring, dry at 110°C for 12h and roast at 550°C for 5h to obtain a hydrolysis catalyst. The amount of Al-Si added is 5% of the mass of the catalyst. %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 99.62%, the selectivity of undecylenic acid is 98.86%, and the yield of undecylenic acid is 98.48%.

Example 5

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reactor a. The methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:3, and the catalyst The amount added accounts for 0.5% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 180° C., the pressure is controlled at 1 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.5mol/L aluminum nitrate, 0.3mol/L zirconium nitrate, 0.05mol/L lanthanum nitrate, 0.3mol/L magnesium nitrate and 0.15mol/L zinc chloride, add 250g citric acid, stir well , to make a sol, then continue stirring at 60°C to form a gel, dry at 110°C for 12 hours, bake at 550°C for 4 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 50:30:5:30:15.

2) Add 5.25g of aluminum nitrate and 50g of 20% mass concentration silica sol to 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite The mass ratio _of sol, _Al2O3 and _SiO2 is 1:8.

3) Take 50g of the composite oxide carrier obtained in step 1) and immerse 67ml of the sol obtained in step 2), and after stirring, dry at 110°C for 12h and roast at 550°C for 5h to obtain a hydrolysis catalyst, the amount of Al-Si added is 8% of the mass of the catalyst %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 99.18%, the selectivity of undecylenic acid is 98.87%, and the yield of undecylenic acid is 98.06%.

Example 6

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reactor a. The methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:3, and the catalyst The addition amount accounts for 2% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 120° C., the pressure is controlled at 0.2 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.4mol/L aluminum nitrate, 0.2mol/L zirconium nitrate, 0.03mol/L lanthanum nitrate, 0.25mol/L magnesium nitrate and 0.14mol/L zinc chloride, add 196g of citric acid, and stir well , to make a sol, then continue to stir at 60°C to form a gel, dry at 120°C for 5 hours, bake at 550°C for 4 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 40:20:3:25:14.

2) Add 5g of aluminum nitrate and 50g of 20% mass concentration silica sol into 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite sol , the mass ratio of Al ₂ O ₃ and SiO ₂ is 1:6.

3) Take 50g of the composite oxide support obtained in step 1) and immerse 58ml of the sol obtained in step 2), and after stirring, dry at 110°C for 12h and roast at 550°C for 5h to obtain a hydrolysis catalyst. The amount of Al-Si added is 7% of the mass of the catalyst. %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 98.01%, the selectivity of undecylenic acid is 99.18%, and the yield of undecylenic acid is 97.21%.

Example 7

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reactor a. The methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:3, and the catalyst The amount added accounts for 2% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 140° C., the pressure is controlled at 0.36 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.4mol/L aluminum nitrate, 0.3mol/L zirconium nitrate, 0.04mol/L lanthanum nitrate, 0.3mol/L magnesium nitrate and 0.12mol/L zinc chloride, add 223g of citric acid, and stir well , to make a sol, then continue stirring at 60°C to form a gel, dry at 110°C for 12 hours, bake at 550°C for 4 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 40:30:4:30:12.

2) Add 7g of aluminum nitrate and 50g of 20% mass concentration silica sol to 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite sol , the mass ratio of Al ₂ O ₃ and SiO ₂ is 1:6.

3) Take 50 g of the composite oxide carrier obtained in step 1) and immerse 50 ml of the sol obtained in step 2), and after stirring, dry at 110° C. for 12 hours and roast at 550° C. for 5 hours to obtain a hydrolysis catalyst. The amount of Al-Si added is 6% of the mass of the catalyst. %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 98.21%, the selectivity of undecylenic acid is 99.15%, and the yield of undecylenic acid is 97.38%.

Example 8

Methyl undecylenate, water and catalyst enter the hydrolysis reactor a from the inlet of the top of the hydrolysis reactor a, after hydrolysis, the methanol vapor enters the condenser b through the outlet of the top of the hydrolysis reactor a, and the condensed methanol enters the methanol recovery tank c, The oil phase in the upper layer of the methanol recovery tank c is pressurized by the pump and then returned to the hydrolysis reactor a. The methanol and water in the lower layer of the methanol recovery tank c enter the methanol rectification tower f for separation; during the reaction process, the mass ratio of oil to water is controlled to be 1:4, and the catalyst The amount added accounts for 2% of the mass of methyl undecylenate, the temperature in the hydrolysis tower is controlled at 200° C., the pressure is controlled at 1.5 MPa, and the stirring speed is controlled at 200 rpm/min.

The undecylenic acid in the upper layer of the hydrolysis reaction kettle a is passed into the precipitation kettle d, and the undecylenic acid in the upper layer of the precipitation kettle d is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower f for refining; the lower layer in the precipitation kettle d The water and the catalyst enter the process water storage tank e together with the lower layer water of the hydrolysis reactor a, the lower layer catalyst of the process water storage tank e is discharged and recycled, and the reacted process water is recycled.

Catalyst preparation method:

1) Measure 1L of mixed solution of 0.45mol/L aluminum nitrate, 0.25mol/L zirconium nitrate, 0.045mol/L lanthanum nitrate, 0.25mol/L magnesium nitrate and 0.11mol/L zinc chloride, add 212g citric acid, and stir well , to make a sol, then continue stirring at 60°C to form a gel, dry at 110°C for 12 hours, bake at 550°C for 4 hours, and cool to room temperature to obtain a composite oxide, a substance of Al, Zr, La, Mg and Zn The volume ratio is 45:25:4.5:25:11.

2) Add 7g of aluminum nitrate and 50g of 20% mass concentration silica sol to 180mL of 5% mass concentration of dilute nitric acid, add 3g of urea, 3g of polyethylene glycol and 3g of ethanolamine during stirring, and age for 12 hours to obtain a stable Al-Si composite sol , the mass ratio of Al ₂ O ₃ and SiO ₂ is 1:6.

3) Take 50g of the composite oxide carrier obtained in step 1) and immerse 42ml of the sol obtained in step 2), and after stirring, dry at 110°C for 12h and roast at 550°C for 5h to obtain a hydrolysis catalyst. The amount of Al-Si added is 5% of the mass of the catalyst. %.

Reaction result: the conversion rate of undecylenic acid methyl ester is 99.12%, the selectivity of undecylenic acid is 98.68%, and the yield of undecylenic acid is 97.81%.

Comparative example 1

No catalyst is added, and the others are the same as in Example 1.

Comparative example 2

Add zinc oxide catalyst, others are with embodiment 1.

Comparative example 3

Catalyst regeneration, only dry, not calcined, other with embodiment 1.

Comparative example 4

The catalyst used is unmodified, and others are the same as in Example 1.

Table 1 Reaction data

Hydrolysis rate of methyl undecylenate/% Undecylenic acid selectivity/% Undecylenic acid yield/% Example 1 99.79 99.22 99.01 Example 2 99.71 99.01 98.72 Example 3 99.72 99.08 98.80 Example 4 99.62 98.86 98.48 Example 5 99.18 98.87 98.06 Example 6 98.01 99.18 97.21 Example 7 98.21 99.15 97.38 Example 8 99.12 98.68 97.81 Comparative example 1 62.27 98.32 61.22 Comparative example 2 70.05 76.11 53.32 Comparative example 3 99.58 99.02 98.60 Comparative example 4 99.75 99.18 98.93

Table 2 Catalyst regeneration data

The results of Examples 1-8 in table 1 show that the process of the present invention has the advantages of high undecylenic acid methyl ester hydrolysis rate, undecylenic acid selectivity and high yield, and the undecylenic acid methyl ester hydrolysis rate can be It can reach more than 98%, the selectivity of undecylenic acid can reach 98.68-99.22%, and the yield of undecylenic acid can reach 97.21-99.01%. The results of Comparative Example 1 show that without using a catalyst, the hydrolysis rate of undecylenic acid methyl ester decreased significantly, the selectivity of undecylenic acid also slightly decreased, and the yield of undecylenic acid was only 61.22%. The results of comparative example 2 show that using zinc oxide as the hydrolysis catalyst, although the hydrolysis rate increases slightly than when no catalyst is used, the selectivity of undecylenic acid decreases significantly, only 76.11%, and the yield of undecylenic acid is 53.32%. The results of Comparative Example 3 show that the catalytic activity of the catalyst of the present invention can be partially recovered after simple drying. The results of Comparative Example 4 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 4 in Table 2 show that after regeneration three times, the yield of undecylenic acid in Example 1 decreases from 99.01% to 96.82%, indicating that the catalyst has a good regeneration effect and can be used repeatedly. This shows that the regeneration method of the present invention has a good regeneration effect. After regeneration three times, the yield of undecylenic acid in Comparative Example 4 dropped from 98.93% to 84.59%. It shows that the catalyst modification method of the present invention helps to keep the activity of the catalyst stable, and has a significant effect on improving the regeneration performance, so that the catalyst can be used repeatedly after simple regeneration, and the production cost is reduced.

Claims (9)

1. A method for preparing undecylenic acid by medium and low temperature catalytic hydrolysis, characterized in that, the preparation method is as follows; Methyl undecylenate, water and catalyst enter the hydrolysis reaction kettle (a) from the top inlet of the hydrolysis reaction kettle (a), and the methanol vapor after hydrolysis enters the condenser (b) through the outlet of the top of the hydrolysis reaction kettle (a), and condenses Finally, methanol enters the methanol recovery tank (c), the upper oil phase of the methanol recovery tank (c) returns to the hydrolysis reactor (a) after being pressurized by a pump, and methanol and water in the lower layer of the methanol recovery tank (c) enter the methanol rectification tower (f ) separation; The undecylenic acid in the upper layer in the hydrolysis reaction kettle (a) is passed into the precipitation kettle (d), and the undecylenic acid in the upper layer in the precipitation kettle (d) is added to wash the undecylenic acid, and the undecylenic acid in the upper layer enters the undecylenic acid refining tower (f ) is refined; the lower layer water and catalyst in the precipitation kettle (d) enter the process water storage tank (e) together with the lower layer water of the hydrolysis reactor (a), and the lower layer catalyst of the process water storage tank (e) is discharged and then recycled, and the process after the reaction Water recycling. 2. The method for preparing undecylenic acid by medium and low temperature catalytic hydrolysis according to claim 1, characterized in that, the reaction temperature of the methyl undecylenate and water in the hydrolysis reactor (a) is 120 to 200°C . 3. The method for preparing undecylenic acid by medium-low temperature catalytic hydrolysis according to claim 1, characterized in that the pressure in the hydrolysis reactor (a) is 0.2-1.5 MPa. 4. The method for preparing undecylenic acid by medium-low temperature catalytic hydrolysis according to claim 1, characterized in that: the mass-number ratio of methyl undecylenic acid to water is 1:0.5-4. 5. The method for preparing undecylenic acid by medium and low temperature catalytic hydrolysis according to claim 1, characterized in that the amount of the modified catalyst added is 0.5 to 2% of the mass of undecylenic acid methyl ester. 6. according to the method for preparing undecylenic acid by middle and low temperature catalytic hydrolysis of claim 1, it is characterized in that, described catalyzer is Al, Zr, La, Mg and Zn composite oxide carrier and is modified with Al-Si sol after roasting , the molar ratio of Al, Zr, La, Mg and Zn is 80-100:40-60:5-10:40-60:20-30. 7. according to the method for preparing undecylenic acid by middle and low temperature catalytic hydrolysis of claim 6, it is characterized in that, the preparation method of described modified catalyst is: the metal precursor salt of composite oxide carrier and the lemon Acid mixed to form a sol, then stirred at 50-80°C to form a gel, dried at 80-120°C for 5-12 hours, calcined at 350-650°C for 3-8 hours, and cooled to room temperature to obtain a composite oxide carrier; Immerse the composite oxide carrier in a sol containing Al and Si, stir and impregnate for 6-12 hours, filter, dry at 80-120°C for 5-12 hours, bake at 350-650°C for 3-8 hours, cool to room temperature, A hydrolysis catalyst was obtained. 8. The medium-low temperature catalytic hydrolysis agent according to claim 6, characterized in that the Al-Si coating accounts for 5-8% of the mass of the catalyst, and the mass ratio of Al ₂ O ₃ to SiO ₂ is 1:5-8. 9. according to the method for preparing undecylenic acid by middle and low temperature catalytic hydrolysis according to claim 7, it is characterized in that, after described hydrolysis catalyst is used, add in the sodium carbonate solution of mass fraction 2% after filtration, precipitation, stir at room temperature Treat for 2-4 hours, filter and wash with appropriate amount of water, dry at 80-150°C for 5-12 hours, and roast at 350-650°C for 3-8 hours to obtain the regenerated catalyst.

Images