CN113603563B - Method for recycling aromatization catalyst - Google Patents
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- CN113603563B CN113603563B CN202110860179.8A CN202110860179A CN113603563B CN 113603563 B CN113603563 B CN 113603563B CN 202110860179 A CN202110860179 A CN 202110860179A CN 113603563 B CN113603563 B CN 113603563B
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/0231—Halogen-containing compounds
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/383—Separation; Purification; Stabilisation; Use of additives by distillation
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C17/00—Preparation of halogenated hydrocarbons
- C07C17/38—Separation; Purification; Stabilisation; Use of additives
- C07C17/395—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to a chemical modification of at least one compound
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- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/06—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by conversion of non-aromatic six-membered rings or of such rings formed in situ into aromatic six-membered rings, e.g. by dehydrogenation
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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/584—Recycling of catalysts
Abstract
The invention discloses a method for recycling an aromatization catalyst, which specifically aims at a halogenated alkane catalyst used in a high-temperature aromatization process of 3, 5-trimethyl-2-cyclohexene-1-one, and comprises the following steps: the cracking gas of high temperature aromatization is treated through deslagging, quenching, further cooling, alkali washing and layering at low temperature, and rectifying separation to obtain chloralkane catalyst, which is then returned to the reaction system. The method separates the haloalkane and the alkali liquor by utilizing the characteristic of extremely slow reaction rate of the haloalkane and the alkali liquor at low temperature, thereby not only reducing the catalyst cost in the production process and reducing the halogen-containing compounds from entering a three-waste system (waste water, waste gas and waste solid), but also carrying out coupling utilization on the heat of the high-temperature pyrolysis gas, and having obvious economic benefit and environmental protection significance.
Description
Technical Field
The invention relates to a method for recycling an aromatization catalyst, in particular to a method for recycling halogenated hydrocarbons serving as a catalyst for high-temperature aromatization by taking 3, 5-trimethyl-2-cyclohexene-1-one as a raw material.
Background
Methyl iodide is a monohydric halohydrocarbon with the molecular formula of CH 3 I, density 2.24g/cm 3 Melting point-66.5 deg.c, boiling point 42.5 deg.c, colorless volatile liquid with malodorous smell, slightly water soluble, alcohol, diethyl ether and other common organic solvent, methyl iodide is one common methylation reagent for organic synthesis.
3, 5-dimethylphenol, MX for short, is an important chemical raw material and an organic synthesis intermediate, and is mainly used for the production of various antibacterial disinfectants, antioxidants, phenolic resins, medicines, pesticides and fuels; but also widely applied to the production of rubber accelerators, anti-aging agents, medicines, fragrances and the like. White crystal at room temperature and molecular formula of C 8 H 10 O, molecular weight 122.17, melting point: 61-64 ℃, boiling point 222 ℃, density: 0.968g/cm 3 The water solubility is 5.3g/L, and the water is easy to dissolve in organic solvents such as ethanol and the like.
At present, the 3, 5-trimethyl-2-cyclohexene-1-one aromatization method is widely adopted for industrially producing 3, 5-dimethylphenol: 3, 5-trimethyl-2-cyclohexene-1-one is taken as a raw material, halogenated hydrocarbon is taken as a homogeneous catalyst, and 3, 5-dimethylphenol is synthesized through high-temperature aromatization. In the main reaction process, one molecule of raw material is removed by halogenated hydrocarbon, then the ketene structure is rearranged to generate 3, 5-dimethylphenol, and main byproducts include m-xylene, o-xylene, mesitylene, m-cresol, 3, 4-dimethylphenol and the like.
In the prior reported process, the catalyst used for synthesizing 3, 5-dimethylphenol by high-temperature aromatization of 3, 5-trimethyl-2-cyclohexene-1-one is treated by alkali liquor neutralization and then is used as wastewater discharge, and the catalyst recovery is less mentioned, so that the defects of low utilization rate of methyl iodide, high three-waste discharge and unutilized heat of pyrolysis gas exist.
Chinese patent CN 101348236A proposes a method for recovering iodin from an iodo alkane catalyst, which comprises condensing a pyrolysis gas aromatized at a high temperature, introducing the condensed pyrolysis gas into an aqueous sodium carbonate solution, and then recovering iodine by acidification and oxidation, wherein it is considered that the catalyst methyl iodide mainly exists in the form of hydrogen iodide generated by decomposition after the reaction is completed, and the recovery of hydrogen iodide is considered, and the recovery of non-decomposed methyl iodide is not mentioned, and the recovery of methyl iodide in the product is not mentioned, and the heat carried by the pyrolysis gas is not utilized.
In summary, in the aromatization reaction disclosed in the prior art, some catalysts are not recycled at all, the generated wastewater containing iodide ions and phenols has poor biodegradability and high treatment difficulty; and the recovery of hydrogen iodide after the decomposition of methyl iodide is only considered, the recovery of methyl iodide is not considered, and compared with iodine, the market price of methyl iodide is hundreds of thousands yuan per ton, so that the methyl iodide has a larger recovery value. Therefore, if a method can be developed to recycle the high-grade heat carried by the pyrolysis gas subjected to high-temperature aromatization and the catalyst methyl iodide which is not decomposed, the method has obvious economic benefit and environmental protection significance.
Disclosure of Invention
The invention aims to fully recycle the haloalkane catalyst in the pyrolysis gas of 3, 5-trimethyl-2-cyclohexene-1-one high-temperature aromatization, and simultaneously recycle the heat of the pyrolysis gas, reduce the production cost, reduce the discharge of three wastes and reduce the pollution to the environment.
The technical scheme of the invention is as follows:
a method for recycling an aromatization catalyst, comprising the steps of:
(1) Deslagging the high-temperature aromatized pyrolysis gas;
(2) Quenching the deslagged pyrolysis gas to obtain a gas-liquid mixed product, and recovering heat of the pyrolysis gas;
(3) Cooling the gas-liquid mixed product in the step (2) to 70-90 ℃ to obtain a condensed product, and performing gas-liquid separation on the condensed product to obtain a liquid condensed product;
(4) Performing alkaline washing layering on the liquid condensate product in the step (3) to obtain an organic phase and a water phase;
(5) Rectifying the organic phase in the step (4), and collecting the front part;
(6) And rectifying the collected front part to obtain the recovered catalyst.
The inventor of the present patent finds through a plurality of experiments that: in the high-temperature aromatization reaction of 3, 5-trimethyl-2-cyclohexene-1-one, the catalyst methyl iodide is expected to be about 20% not decomposed except hydrogen iodide, and the recovery method in the prior art is not aware that the part of methyl iodide can be recovered, only alkali liquor is adopted for treatment, the iodine is recovered in the form of crude iodine, the methyl iodide is directly decomposed in the process, and the methyl iodide has higher value and is more significant to recover. As the reaction condition of methyl iodide and alkali liquor is freshly reported, the inventor of the patent further researches the reaction of methyl iodide and alkali liquor, and quantitatively adds methyl iodide into 3, 5-dimethylphenol pure products, and reacts with 10% sodium carbonate solution at different temperatures under a stirring state, low-temperature water is used for reflux in the heating process, and a preheated glass syringe is used for sampling. By gas chromatography, heating at 70deg.C for 1 hr with a reduction of methyl iodide of <5%; whereas heating to 100 ℃ for 1 hour reduced methyl iodide by 89% and was completely neutralized at 1.5 hours, demonstrating that methyl iodide reacted very slowly with sodium carbonate solution below 70 ℃. According to the reaction characteristics of methyl iodide and alkali liquor, the invention provides a method for recycling the aromatization catalyst, which controls the condensation product at 70-90 ℃, then mixes the condensation product with the alkali liquor, and further reduces the temperature, so that the residual methyl iodide is not decomposed basically and can be fully recycled.
Preferably, the pyrolysis gas of high-temperature aromatization is a product obtained by taking 3, 5-trimethyl-2-cyclohexene-1-one as a raw material and methyl iodide as a catalyst, and synthesizing 3, 5-dimethylphenol through high-temperature aromatization at the reaction temperature of 500-600 ℃.
Preferably, in step (1), solid particles carried in the pyrolysis gas of high temperature aromatization are removed by cyclone separator, and the diameter of the separated solid particles is more than 20 μm, so as to reduce the risk of pipeline blockage.
Preferably, in the step (2), the pyrolysis gas after deslagging is subjected to heat exchange quenching with pure water, the pyrolysis gas is cooled to be a gas-liquid mixture product with the temperature of 180-200 ℃, and the pure water is prepared into low-pressure steam with the pressure of less than 0.6MPa so as to recover the heat of the pyrolysis gas.
Preferably, in the step (3), the gas-liquid mixed product and the raw material 3, 5-trimethyl-2-cyclohexene-1-one of the aromatization reaction are subjected to coupling heat exchange and cooling, and the temperature of the obtained condensation product is 70-90 ℃. The heat of the pyrolysis gas is further recovered, and then the condensed product carrying methane gas is subjected to gas-liquid separation to obtain a liquid condensed product.
Preferably, in the step (4), alkali liquor with the concentration of 10-20% is used for neutralization with the liquid condensate product to neutralize the acidic component and reduce equipment corrosion, wherein the alkali liquor is sodium carbonate or sodium bicarbonate water solution, preferably sodium carbonate water solution; alkali liquor and the liquid condensate product are mixed according to the mass ratio of (1-2): 10, mixing, neutralizing for 10-30 min, controlling the temperature at 65-70 ℃, and controlling the pH value of the water phase after neutralization to be 7-8; standing for 30-60 min, layering, wherein the upper layer is separated to obtain an organic phase, and the lower layer is a water phase.
Preferably, in the step (5), the organic phase is rectified under the condition of reduced pressure, the pressure is less than or equal to-0.092 MPa, the reflux ratio is 1-3, and the top of the tower is provided with a front part with the boiling point less than or equal to 120 ℃; the precursor composition comprises methyl iodide, dimethylbenzene, mesitylene, 3, 4-dimethylphenol and 3, 5-dimethylphenol.
Preferably, in the step (6), the pre-fraction is subjected to normal pressure rectification, the reflux ratio is 1-2, the fraction with the boiling range of 40-45 ℃ is extracted from the top of the column, and the recovered catalyst is fully applied to the reaction system.
The invention recycles the heat carried by the pyrolysis gas of high-temperature aromatization, thereby saving energy consumption; the residual methyl iodide catalyst in the pyrolysis gas is recycled, so that the utilization rate of the methyl iodide catalyst is improved, and the halogen-containing compound is reduced from entering the three-waste system. Not only reduces the production cost, but also reduces the discharge of three wastes and is more beneficial to environmental protection.
Drawings
Fig. 1 is a schematic process flow diagram of a method for recycling an aromatization catalyst according to an embodiment of the present invention.
Detailed Description
In order to facilitate the explanation of the technical contents, the attained objects and effects of the present invention, the following description will be made with reference to the specific embodiments.
Fig. 1 is a flow chart of a method for carrying out the present invention, and as shown in fig. 1, the method for recycling an aromatization catalyst comprises: a deslagging step of pyrolysis gas subjected to high-temperature aromatization so as to reduce the risk of pipeline blockage; cooling the deslagged pyrolysis gas to 180-200 ℃ by pure water; the gas-liquid mixed product from the quenching step and the raw material 3, 5-trimethyl-2-cyclohexene-1-one are subjected to a coupling heat exchange cooling step; performing an alkaline washing layering step on the liquid condensate product from the coupling heat exchange cooling step to neutralize the acidic component and reduce equipment corrosion; the step of decompressing, rectifying and removing the front part from the alkaline-washed layered organic phase; and (3) carrying out normal pressure rectification on the collected front part to recover the catalyst, wherein the recovered catalyst is completely applied to a reaction system.
The pyrolysis gas for high-temperature aromatization is characterized in that: 1 to 5 percent of 3, 5-trimethyl-2-cyclohexene-1-ketone, 77 to 81 percent of 3, 5-dimethylphenol, 10 to 11 percent of methane gas, 1 to 5 percent of m-xylene, 0.5 to 1.5 percent of 3, 4-dimethylphenol, 0.2 to 0.4 percent of methyl iodide and the like, wherein the temperature of the pyrolysis gas for high-temperature aromatization is 500 to 600 ℃.
The method comprises the following processing procedures: deslagging, quenching, coupling heat exchange, alkali washing layering, front part removal and front part rectification.
Deslagging: the pyrolysis gas subjected to high-temperature aromatization carries solid particles formed by decomposing and carbonizing materials, the solid particles are removed by a cyclone separator, the solid particles and tar substances are prevented from being aggregated, equipment is blocked, the diameter of the separated solid particles is more than 20 mu m, and the pressure drop of the cyclone separator is less than 1kpa.
Quenching: and (3) exchanging heat between the high-temperature aromatized pyrolysis gas after deslagging and pure water through a quenching heat exchanger, cooling the pyrolysis gas to a gas-liquid mixed product with the temperature of 180-200 ℃, and preparing the pure water into low-pressure steam with the pressure of below 0.6MPa to recover the heat of the pyrolysis gas.
And (3) coupling heat exchange: and carrying out coupling heat exchange and cooling on the gas-liquid mixed product and the raw material 3, 5-trimethyl-2-cyclohexene-1-one of the aromatization reaction, preheating the raw material, condensing the product at 70-90 ℃, then carrying out gas-liquid separation on the condensed product carrying methane gas to obtain a liquid condensed product, and carrying out incineration treatment on the methane gas after the gas-liquid separation.
Alkali washing and layering: neutralizing the liquid condensate product by using alkali liquor, and preparing solid alkali into alkali liquor with the concentration of 10% -20%, wherein the solid alkali is sodium carbonate and sodium bicarbonate, and sodium carbonate is preferred; alkali liquor and the liquid condensate product are mixed according to the mass ratio of (1-2): 10, mixing, neutralizing for 10-30 min, controlling the temperature to 65-70 ℃, and controlling the pH value of the water phase after neutralization to be 7-8; standing for 30-60 min, layering, wherein the upper layer is separated to obtain an organic phase, and the lower layer is iodine-containing wastewater.
Removing the following parts: rectifying the organic phase under the condition of reduced pressure, wherein the pressure is less than or equal to-0.092 MPa, the reflux ratio is 1-3, the boiling point of the tower top is less than or equal to 120 ℃, and the tower bottom liquid is purified to obtain a 3, 5-dimethylphenol product; the composition of the precursor comprises methyl iodide, dimethylbenzene, mesitylene, 3, 4-dimethylphenol and 3, 5-dimethylphenol.
And (3) rectifying the front parts: and (3) rectifying the front part of the methyl iodide-containing catalyst under normal pressure, wherein the reflux ratio is 1-2, and the fraction with the boiling range of 40-45 ℃ is extracted from the top of the tower, so that the recovery of the non-decomposed methyl iodide catalyst is realized, and the recovered catalyst is fully applied to a reaction system.
Further description will be given below with reference to specific examples. The high-temperature aromatization mentioned in the invention is the prior art, and can refer to patent documents such as US4086862, CN 1583697A and the like, the specific condition has no obvious influence on the recycling method, and the recycling method can be adopted only by adopting methyl iodide as a catalyst. In the following examples, unless otherwise specified, aromatization refers to aromatization reaction at 500 to 600 ℃ with 3, 5-trimethyl-2-cyclohexen-1-one as raw material and methyl iodide as catalyst.
Example 1
3, 5-trimethyl-2-cyclohexen-1-one (25.03 kg,181 mol) was continuously pumped into the coupled heat exchanger shell side (heat exchange area 120 cm) 2 ) Then enters a reactor together with catalyst methyl iodide (250.10 g,1.76 mol) to carry out aromatization reaction under the aromatization reaction condition; the obtained pyrolysis gas is deslagged by a cyclone separator with the diameter of 50mm, and enters a quenching device (the heat exchange area is 31 cm) 2 ) The method comprises the steps of carrying out a first treatment on the surface of the The material outlet temperature of the coupling heat exchanger is gradually stabilized at 73-81 ℃ to form a condensed product carrying methane gas, the condensed product is separated by gas and liquid to obtain 21.97kg of liquid condensed product, and the density is 0.966g/cm 3 The methyl iodide content was measured by the external standard method to be 2.23g/L.
Adding sodium carbonate solution (2.20 kg, mass content 10%) into the liquid condensate, neutralizing while stirring, controlling the neutralization temperature at 65-70 ℃ for 10min, standing for 30min, and layering; 22.31kg of an organic phase and an aqueous phase (1.77 kg, pH 7) were obtained. Adding 160.23g of 36% hydrochloric acid into the water phase for acidification, dropwise adding 30% hydrogen peroxide (100.06 g,0.74 mol) into the water phase for reaction for 1h, and carrying out suction filtration to obtain 158.29g of crude iodine with the iodine content of 90.31%.
The organic phase is subjected to reduced pressure rectification in batches to remove the front part, the tower height is 800mm, the absolute pressure is 8kPa, the reflux ratio is 3, the front part with the tower top temperature less than or equal to 118.9 ℃ is collected, and 2.34kg of front part is obtained.
The front part is rectified under normal pressure, the tower height is 500mm, the reflux ratio is 2, the component with the distillation range of 40-45 ℃ is collected at the tower top, the catalyst methyl iodide (48.37 g) is recovered, the content of methyl iodide measured by an internal standard method is 94.7%, the total recovery rate of iodine is 82.25% (the recovery rate of methyl iodide is 18.32%, and the recovery rate of crude iodine is 63.93%).
Comparative example 1
3, 5-trimethyl-2-cyclohexen-1-one (25.00 kg,181 mol) and methyl iodide (250.20 g,1.76 mol) as catalyst were introduced into the reactor under aromatization conditions to carry out aromatization. The high-temperature pyrolysis gas is introduced into the tower kettle of an alkaline washing tower in a bubbling mode, sodium carbonate solution (4.00 kg, mass content of 10%) is filled in the tower kettle of the alkaline washing tower, the tower top of the alkaline washing tower is condensed and refluxed through a circulating water condenser, methane gas is discharged from the tower top, the sodium carbonate aqueous solution is gradually boiled, and the temperature of the tower kettle is 108 ℃.
After the reaction, the mixture was separated into layers while it was still hot, and 3.28kg of a water phase was obtained. Adding 300.09g of 36% hydrochloric acid into the water phase for acidification, then dropwise adding 30% hydrogen peroxide (150.12 g,1.32 mol) into the water phase for reaction for 1h, and carrying out suction filtration to obtain 198.00g of crude iodine, wherein the iodine content is 89.91%, and the total iodine recovery rate is 79.57%.
As can be seen from the results of example 1 and comparative example 1, the overall recovery rate of iodine by the method of the present application is improved to a certain extent compared with the prior art, and more importantly, about one fifth of iodine recovered by the method of the present invention exists in the form of higher value methyl iodide, and the purity is about 95%, so that the iodine can be used as a catalyst; the crude iodine is recovered according to the prior art, the content of the crude iodine is below 90%, and further purification is needed.
Example 2
3, 5-trimethyl-2-cyclohexen-1-one (25.01 kg,181 mol) was continuously pumped into the coupled heat exchanger shell side (heat exchange area 120 cm) 2 ) Then enters a reactor together with catalyst methyl iodide (375.13 g,2.64 mol) to carry out aromatization reaction under the aromatization reaction condition; deslagging the high-temperature pyrolysis gas obtained by the aromatization reaction by a 50mm cyclone separator, and feeding the deslagged pyrolysis gas into a quenching device (the heat exchange area is 31 cm) 2 ) The method comprises the steps of carrying out a first treatment on the surface of the The quenching device is cooled by a small amount of hot water, and the flow rate of the hot water is controlled to quenchThe outlet temperature of the materials of the coupling heat exchanger is stabilized at 187-195 ℃, the products are condensed to form a gas-liquid mixture, the gas-liquid mixture enters a tube side of the coupling heat exchanger to preheat the 3, 5-trimethyl-2-cyclohexene-1-one of the next batch of raw materials to 134-140 ℃, the outlet temperature of the materials of the coupling heat exchanger is gradually stabilized at 73-85 ℃, the condensed products carrying methane gas are formed, 22.07kg of liquid condensed products are obtained through gas-liquid separation, and the methyl iodide content is measured to be 3.55g/L by an external standard method.
Adding sodium carbonate solution (4.41 kg, mass content 10%) into the liquid condensate, neutralizing while stirring, controlling the neutralization temperature at 65-70 ℃ for 10min, standing for 30min, and layering; 22.74kg of an organic phase and an aqueous phase (3.63 kg, pH 8) were obtained. Adding 300.11g of 36% hydrochloric acid into the water phase for acidification, dropwise adding 30% hydrogen peroxide (150.03 g,1.32 mol) into the water phase for reaction for 1h, and carrying out suction filtration to obtain 244.70g of crude iodine with the iodine content of 89.84%.
The organic phase is subjected to reduced pressure rectification in batches to remove the front part, the tower height is 800mm, the absolute pressure is 6kPa, the reflux ratio is 3, the front part with the tower top temperature less than or equal to 109.9 ℃ is collected, and 2.63kg of front part is obtained.
The front part is rectified under normal pressure, the tower height is 500mm, the reflux ratio is 2, the components with the distillation range of 40-45 ℃ are collected at the tower top, the catalyst methyl iodide (77.25 g) is recovered, the content of methyl iodide measured by an internal standard method is 94.2%, the total recovery rate of iodine is 84.95% (the recovery rate of methyl iodide is 19.40%, and the recovery rate of crude iodine is 65.55%).
Example 3
3, 5-trimethyl-2-cyclohexen-1-one (25.00 kg,181 mol) was continuously pumped into the coupled heat exchanger shell side (heat exchange area 120 cm) 2 ) Then enters a reactor together with catalyst methyl iodide (500.07 g,3.52 mol) to carry out aromatization reaction under the aromatization reaction condition; deslagging the high-temperature pyrolysis gas obtained by the aromatization reaction by a 50mm cyclone separator, and feeding the deslagged pyrolysis gas into a quenching device (the heat exchange area is 31 cm) 2 ) The method comprises the steps of carrying out a first treatment on the surface of the The quenching device is cooled by a small amount of hot water, the flow rate of the hot water is controlled to ensure that the temperature of the material outlet of the quenching device is stabilized at 186-195 ℃, the product is condensed to form a gas-liquid mixture, and the gas-liquid mixture enters a tube pass of a coupling heat exchanger to carry out the next batch of raw materialsThe material 3, 5-trimethyl-2-cyclohexene-1-one is preheated to 135-141 ℃, the material outlet temperature of the coupling heat exchanger is gradually stabilized at 76-87 ℃ to form a condensed product carrying methane gas, the condensed product is subjected to gas-liquid separation to obtain 22.24kg of liquid condensed product, and the content of methyl iodide is measured to be 4.86g/L by an external standard method.
Adding sodium carbonate solution (4.48 kg, mass content 10%) into the liquid condensate, neutralizing while stirring, controlling the neutralization temperature at 65-70 ℃ for 10min, standing for 30min, and layering; 22.80kg of an organic phase and an aqueous phase (3.81 kg, pH 7) were obtained. Adding 300.11g of 36% hydrochloric acid into the water phase for acidification, dropwise adding 30% hydrogen peroxide (150.03 g,1.32 mol) into the water phase for reaction for 1h, and carrying out suction filtration to obtain 319.09g of crude iodine, wherein the iodine content is 89.92%.
The organic phase is subjected to reduced pressure rectification in batches to remove the front part, the tower height is 800mm, the absolute pressure is 6kPa, the reflux ratio is 3, the front part with the tower top temperature less than or equal to 110 ℃ is collected, and 2.50kg of front part is obtained.
The front part is rectified under normal pressure, the tower height is 500mm, the reflux ratio is 2, the components with the distillation range of 40-45 ℃ are collected at the tower top, the catalyst methyl iodide (105.53 g) is recovered, the content of methyl iodide measured by an internal standard method is 94.5%, the total recovery rate of iodine is 84.12% (the recovery rate of methyl iodide is 19.94%, and the recovery rate of crude iodine is 64.18%).
The invention can realize the utilization of heat carried by pyrolysis gas of high-temperature aromatization, and simultaneously realize the recovery of the catalyst methyl iodide which is not decomposed in the pyrolysis gas, and the recovered catalyst is fully applied to a reaction system. Not only saves energy consumption, but also improves the utilization rate of methyl iodide, reduces the production cost, reduces the halogen-containing compounds from entering the three-waste system, and has obvious economic benefit and environmental protection significance.
Claims (9)
1. A method for recycling an aromatization catalyst, comprising the steps of:
(1) Deslagging the aromatized pyrolysis gas;
(2) Quenching the deslagged pyrolysis gas to obtain a gas-liquid mixed product, and recovering heat of the pyrolysis gas;
(3) Cooling the gas-liquid mixed product in the step (2) to 70-90 ℃ to obtain a condensed product, and performing gas-liquid separation on the condensed product to obtain a liquid condensed product;
(4) Performing alkaline washing layering on the liquid condensate product in the step (3) to obtain an organic phase and a water phase;
(5) Rectifying the organic phase in the step (4), and collecting the front part;
(6) Rectifying the collected front part to obtain a recovered catalyst;
in the step (1), the aromatized pyrolysis gas is a product of synthesizing 3, 5-dimethylphenol through aromatization by taking 3, 5-trimethyl-2-cyclohexene-1-one as a raw material and methyl iodide as a catalyst, wherein the reaction temperature is 500-600 ℃;
in the step (4), alkali liquor is used for neutralizing the liquid condensate product, and the temperature is controlled between 65 and 70 ℃.
2. The method for recycling an aromatization catalyst according to claim 1, wherein in the step (1), the deslagging is carried out by removing solid particles carried in an aromatized pyrolysis gas through a cyclone.
3. The method for recycling aromatization catalyst according to claim 1, wherein in the step (2), the deslagged pyrolysis gas is subjected to heat exchange quenching with pure water, the pyrolysis gas is cooled to a gas-liquid mixture product of 180-200 ℃, and the pure water is prepared into low-pressure steam of less than 0.6MPa to recycle the heat of the pyrolysis gas.
4. The method for recycling aromatization catalyst according to claim 1, wherein in the step (3), the gas-liquid mixture product and the raw material 3, 5-trimethyl-2-cyclohexene-1-one of aromatization reaction are subjected to coupling heat exchange and cooling, and then the condensed product carrying methane gas is subjected to gas-liquid separation, so as to obtain a liquid condensed product.
5. The method for recycling an aromatization catalyst according to claim 1, wherein in the step (4), the alkali liquor and the liquid condensate product are mixed according to the mass ratio (1-2): 10, mixing, wherein the neutralization time is 10-30 min, and the pH value of the water phase after neutralization is=7-8; standing for 30-60 min, and layering to obtain an organic phase and a water phase.
6. The method for recycling aromatization catalyst according to claim 5, wherein the alkali solution is aqueous solution of sodium carbonate or sodium bicarbonate, and the concentration of the alkali solution is 10-20wt%.
7. The method for recycling aromatization catalyst according to claim 1, wherein in the step (5), the organic phase is rectified under the condition of reduced pressure, the pressure is less than or equal to-0.092 MPa, the reflux ratio is 1-3, and the top of the tower is provided with a front part with the boiling point less than or equal to 120 ℃; the composition of the precursor comprises methyl iodide, dimethylbenzene, mesitylene, 3, 4-dimethylphenol and 3, 5-dimethylphenol.
8. The method for recycling aromatization catalyst according to claim 1, wherein in the step (6), the pre-fraction is rectified at normal pressure, the reflux ratio is 1-2, and the fraction with the boiling range of 40-45 ℃ is obtained from the top of the tower, namely the recycled catalyst.
9. The method for recycling aromatization catalyst according to claim 8, wherein the recovered catalyst is applied to the aromatization reaction system in its entirety.
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|---|---|---|---|---|
| EP0075730A1 (en) * | 1981-09-23 | 1983-04-06 | Hoechst Aktiengesellschaft | Process for the recovery of iodine values from gaseous effluents derived from carbonylation reactions |
| JP2005021861A (en) * | 2003-07-02 | 2005-01-27 | Nippo Kagaku Kk | Alkyl iodide recovery method and alkyl iodide recovery apparatus |
| CN101348236A (en) * | 2008-09-12 | 2009-01-21 | 湖南利洁生物化工有限公司 | Method for recovering iodine from alkyl iodides catalyst |
| CN111875472A (en) * | 2020-07-23 | 2020-11-03 | 江苏南大光电材料股份有限公司 | Method for recovering methyl iodide from iodine-containing residual liquid |
| CN113120925A (en) * | 2021-04-16 | 2021-07-16 | 湖南瑞冠生物化工科技有限公司 | Method for recovering iodide from isophorone cracking material |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0075730A1 (en) * | 1981-09-23 | 1983-04-06 | Hoechst Aktiengesellschaft | Process for the recovery of iodine values from gaseous effluents derived from carbonylation reactions |
| JP2005021861A (en) * | 2003-07-02 | 2005-01-27 | Nippo Kagaku Kk | Alkyl iodide recovery method and alkyl iodide recovery apparatus |
| CN101348236A (en) * | 2008-09-12 | 2009-01-21 | 湖南利洁生物化工有限公司 | Method for recovering iodine from alkyl iodides catalyst |
| CN111875472A (en) * | 2020-07-23 | 2020-11-03 | 江苏南大光电材料股份有限公司 | Method for recovering methyl iodide from iodine-containing residual liquid |
| CN113120925A (en) * | 2021-04-16 | 2021-07-16 | 湖南瑞冠生物化工科技有限公司 | Method for recovering iodide from isophorone cracking material |
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