Method for recycling aromatization catalyst
阅读说明：本技术 一种芳构化催化剂回收利用的方法 (Method for recycling aromatization catalyst ) 是由 毛建拥 王丰阳 胡鹏翔 王会 龚琴琴 李泉 王启刚 潘洪 范金皓 俞宏伟 胡柏剡 于 2021-07-28 设计创作，主要内容包括：本发明公开了一种芳构化催化剂回收利用的方法,具体针对3,5,5-三甲基-2-环己烯-1-酮高温芳构化过程中所用卤代烷烃催化剂,该方法包括以下步骤：将高温芳构化的裂解气通过除渣,急冷、进一步冷却,再经低温下碱洗分层,然后精馏分离得到氯代烷烃催化剂,套回至反应体系。该方法是利用卤代烷与碱液在低温下反应速率极慢的特点对其进行分离,不仅降低了生产过程中催化剂成本,减少了含卤化合物进入三废系统(废水、废气、废固),同时对高温裂解气热量进行了耦合利用,具有显著的经济效益和环保意义。(The invention discloses a method for recycling an aromatization catalyst, and particularly relates to a halogenated alkane catalyst used in a high-temperature aromatization process of 3,5, 5-trimethyl-2-cyclohexene-1-ketone, which comprises the following steps: the high-temperature aromatization cracking gas is subjected to deslagging, quenching, further cooling, alkali washing layering at low temperature, rectification separation to obtain chloralkane catalyst, and the chloralkane catalyst is recycled to a reaction system. The method separates the alkyl halide and the alkali liquor by utilizing the characteristic that the reaction rate of the alkyl halide and the alkali liquor is extremely low at low temperature, so that the catalyst cost in the production process is reduced, the halogen-containing compounds entering a three-waste system (waste water, waste gas and waste solids) are reduced, the heat of high-temperature pyrolysis gas is coupled and utilized, and the method has obvious economic benefit and environmental protection significance.)
1. A method for recycling an aromatization catalyst is characterized by comprising the following steps:
(1) deslagging the pyrolysis gas subjected to high-temperature aromatization;
(2) quenching the cracked gas after deslagging to obtain a gas-liquid mixed product, and recovering the heat of the cracked gas;
(3) further cooling the gas-liquid mixed product obtained 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) carrying out alkaline washing layering on the liquid condensation product obtained in the step (3) to obtain an organic phase and a water phase;
(5) rectifying the organic phase obtained in the step (4), and collecting the first part;
(6) rectifying the collected former part to obtain the recovered catalyst.
2. The method for recycling the aromatization catalyst according to claim 1, wherein in the step (1), the pyrolysis gas subjected to high-temperature aromatization is a product obtained by synthesizing 3,5, 5-trimethyl-2-cyclohexene-1-one as a raw material and methyl iodide as a catalyst at a reaction temperature of 500-600 ℃ into 3, 5-dimethylphenol through high-temperature aromatization.
3. The method for recycling an aromatization catalyst according to claim 1, wherein in the step (1), the deslagging is to remove solid particles carried in the pyrolysis gas of high-temperature aromatization by a cyclone separator.
4. The method for recycling the aromatization catalyst according to claim 1, wherein in the step (2), the cracked gas after deslagging is subjected to heat exchange and quenching with pure water, the cracked gas is cooled to a gas-liquid mixed product at 180-200 ℃, and the pure water is prepared into low-pressure steam of less than 0.6MPa to recycle the heat of the cracked gas.
5. The method for recycling the aromatization catalyst according to claim 1, wherein in the step (3), the gas-liquid mixed product and the aromatization raw material 3,5, 5-trimethyl-2-cyclohexene-1-ketone are subjected to coupling heat exchange for cooling, and then the condensation product carrying methane gas is subjected to gas-liquid separation to obtain a liquid condensation product.
6. The method for recycling the aromatization catalyst according to claim 1, wherein in the step (4), the liquid condensation product is neutralized by using alkali liquor, and the mass ratio of the alkali liquor to the liquid condensation product is (1-2): 10, mixing, wherein the neutralization time is 10-30 min, the temperature is controlled to be 65-70 ℃, and the pH value of a neutralized water phase is 7-8; standing for 30-60 min, and layering to obtain an organic phase and a water phase.
7. The method for recycling the aromatization catalyst according to claim 6, wherein the alkali liquor is an aqueous solution of sodium carbonate or sodium bicarbonate, and the concentration of the alkali liquor is 10 to 20 wt%.
8. The method for recycling the aromatization catalyst according to claim 1, wherein in the step (5), the organic phase is rectified under reduced pressure, the pressure is less than or equal to-0.092 MPa, the reflux ratio is 1-3, and the front part with the boiling point less than or equal to 120 ℃ is extracted from the top of the tower; the former components comprise methyl iodide, xylene, mesitylene, 3, 4-dimethylphenol and 3, 5-dimethylphenol.
9. The method for recycling the aromatization catalyst according to claim 1, wherein in the step (6), the first fraction is rectified under normal pressure, the reflux ratio is 1-2, and a fraction with the boiling range of 40-45 ℃ is extracted from the top of the tower, namely the recycled catalyst.
10. The method of recycling an aromatization catalyst according to claim 9 wherein the recovered catalyst is totally recycled to the aromatization reaction system.
Technical Field
The invention relates to a method for recycling an aromatization catalyst, in particular to a method for recycling halogenated alkane of a catalyst used for high-temperature aromatization by taking 3,5, 5-trimethyl-2-cyclohexene-1-ketone as a raw material.
Background
Methyl iodide is a monohalogenated hydrocarbon of the formula CH3I, density 2.24g/cm3Melting point is-66.5 ℃, boiling point is 42.5 ℃, the product is colorless volatile liquid at room temperature, has foul smell, is slightly soluble in water, is dissolved in common organic solvents such as ethanol, ether and the like, and methyl iodide is a common methylating agent in organic synthesis.
3, 5-dimethylphenol, MX for short, is importantChemical raw materials and organic synthesis intermediates, which are mainly used for producing various antibacterial disinfectants, antioxidants, phenolic resins, medicines, insecticides and fuels; it is also widely used in the production of rubber accelerators, anti-aging agents, medicaments, spices and the like. White crystal at room temperature and molecular formula C8H10O, molecular weight 122.17, melting point: 61-64 ℃, boiling point 222 ℃, density: 0.968g/cm3The water solubility is 5.3g/L, and the water-soluble organic solvent is easy to dissolve in organic solvents such as ethanol.
At present, 3,5, 5-trimethyl-2-cyclohexene-1-ketone aromatization method is widely adopted for industrial production of 3, 5-dimethylphenol: 3,5, 5-trimethyl-2-cyclohexene-1-ketone is used as a raw material, halogenated hydrocarbon is used as a homogeneous catalyst, and 3, 5-dimethylphenol is synthesized by high-temperature aromatization. In the main reaction process, one molecule of raw material is subjected to removal of one molecule of methane under the action of halogenated hydrocarbon, and the ketene structure is rearranged to generate 3, 5-dimethylphenol, wherein main byproducts comprise m-xylene, o-xylene, mesitylene, m-cresol, 3, 4-dimethylphenol and the like.
In the existing reported process, all catalysts used for synthesizing 3, 5-dimethylphenol from 3,5, 5-trimethyl-2-cyclohexene-1-ketone through high-temperature aromatization are treated by alkali liquor neutralization and then discharged as wastewater, less catalyst recovery is mentioned, and the defects that the catalyst is low in methyl iodide utilization rate, high in three-waste discharge and unused in pyrolysis gas heat exist.
Chinese patent CN 101348236 a proposes a method for recovering iodine from an alkane iodide catalyst, in which pyrolysis gas aromatized at high temperature is condensed and introduced into a sodium carbonate aqueous solution, and then iodine is recovered by acidification and oxidation, so it is considered that the catalyst methyl iodide mainly exists in the form of hydrogen iodide generated by decomposition after the reaction is finished, and the recovery of hydrogen iodide is considered, and it is not mentioned that there may exist undecomposed methyl iodide, nor is it mentioned that methyl iodide in the product is recovered, and in addition, heat carried by the pyrolysis gas is not utilized.
In conclusion, in the aromatization reaction disclosed in the prior art, some catalysts are not recovered, the generated wastewater containing iodide ions and phenols has poor biochemical property and great treatment difficulty; and some methods only consider the recovery of hydrogen iodide after the decomposition of the methyl iodide, do not consider the recovery of the methyl iodide, and have higher recovery value compared with iodine because the market price of the methyl iodide is more than ten thousand yuan per ton. Therefore, if a method can be developed for recycling high-grade heat carried by pyrolysis gas subjected to high-temperature aromatization and 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 halogenated alkane catalyst in the cracking gas of 3,5, 5-trimethyl-2-cyclohexene-1-ketone high-temperature aromatization, simultaneously recycle the heat of the cracking gas, reduce the production cost, and reduce the discharge of three wastes and the pollution to the environment.
The technical scheme of the invention is as follows:
a method for recycling an aromatization catalyst comprises the following steps:
(1) deslagging the pyrolysis gas subjected to high-temperature aromatization;
(2) quenching the cracked gas after deslagging to obtain a gas-liquid mixed product, and recovering the heat of the cracked gas;
(3) further cooling the gas-liquid mixed product obtained 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) carrying out alkaline washing layering on the liquid condensation product obtained in the step (3) to obtain an organic phase and a water phase;
(5) rectifying the organic phase obtained in the step (4), and collecting the first part;
(6) rectifying the collected former part to obtain the recovered catalyst.
The inventor of the patent finds that through multiple experiments: in the 3,5, 5-trimethyl-2-cyclohexene-1-ketone high-temperature aromatization reaction, catalyst methyl iodide is still predicted to be decomposed to about 20 percent except hydrogen iodide, but the recovery methods in the prior art are not aware that the part of methyl iodide can be recovered, and only alkali liquor is considered for treatment to recover iodine in the form of crude iodine, the methyl iodide is directly decomposed in the process, and the value of the methyl iodide is higher, so that the recovery is more meaningful. The reaction conditions of the methyl iodide and the alkali liquor are reported, so the inventor of the patent further researches the reaction of the methyl iodide and the alkali liquor, quantitatively adds the methyl iodide into a pure product of the 3, 5-dimethylphenol, reacts with a 10% sodium carbonate solution at different temperatures under a stirring state, uses low-temperature water for reflux in the heating process, and takes a sample by using a preheated glass syringe. After gas chromatographic analysis, the reduction amount of the methyl iodide is less than 5 percent when the mixture is heated for 1 hour at 70 ℃; while heating up to 100 ℃ for 1 hour reduced the methyl iodide by 89% and was completely neutralized in 1.5 hours, thus demonstrating that below 70 ℃, methyl iodide reacts very slowly with sodium carbonate solution. Therefore, the invention provides the method for recycling the aromatization catalyst according to the reaction characteristics of methyl iodide and alkali liquor, and the method controls the temperature of a condensation product to be 70-90 ℃, then mixes the condensation product with the alkali liquor, and further reduces the temperature, so that the residual methyl iodide is basically not decomposed and can be fully recycled.
Preferably, the pyrolysis gas of high-temperature aromatization is a product synthesized by using 3,5, 5-trimethyl-2-cyclohexene-1-ketone as a raw material and methyl iodide as a catalyst and carrying out high-temperature aromatization at 500-600 ℃ to synthesize 3, 5-dimethylphenol.
Preferably, in step (1), solid particles carried in the pyrolysis gas subjected to high-temperature aromatization are removed by a cyclone separator, and the diameter of the separated solid particles is more than 20 μm, so that the risk of pipeline blockage is reduced.
Preferably, in the step (2), the cracked gas after deslagging is subjected to heat exchange and quenching with pure water, the cracked gas is cooled to be a gas-liquid mixed product at 180-200 ℃, and the pure water is prepared into low-pressure steam of less than 0.6MPa so as to recover the heat of the cracked gas.
Preferably, in the step (3), the gas-liquid mixed product and the aromatization raw material 3,5, 5-trimethyl-2-cyclohexene-1-ketone are subjected to coupling heat exchange for cooling, and the temperature of the obtained condensation product is 70-90 ℃. Further recovering the heat of the cracked gas, and then carrying out gas-liquid separation on the condensation product carrying the methane gas to obtain a liquid condensation product.
Preferably, in the step (4), alkali liquor with the concentration of 10-20% is used for neutralizing the liquid condensation product so as to neutralize acid components and reduce equipment corrosion, and the alkali liquor is an aqueous solution of sodium carbonate or sodium bicarbonate, preferably an aqueous solution of sodium carbonate; and (3) mixing alkali liquor with the liquid condensation product according to the mass ratio (1-2): 10, mixing, neutralizing for 10-30 min, controlling the temperature at 65-70 ℃, and neutralizing to obtain a water phase with the pH of 7-8; standing for 30-60 min, layering, and separating the upper layer to obtain an organic phase and the lower layer to obtain a water phase.
Preferably, in the step (5), the organic phase is rectified under reduced pressure, the pressure is less than or equal to-0.092 MPa, the reflux ratio is 1-3, and the front part with the boiling point less than or equal to 120 ℃ is extracted from the top of the tower; the former components include methyl iodide, xylene, mesitylene, 3, 4-dimethylphenol and 3, 5-dimethylphenol.
Preferably, in the step (6), the former part is rectified under normal pressure, the reflux ratio is 1-2, fractions with the boiling range of 40-45 ℃ are extracted from the tower top, and all recovered catalysts are applied to a reaction system.
The invention recycles the heat carried by the pyrolysis gas of high-temperature aromatization, thus saving energy consumption; the residual methyl iodide catalyst in the cracked gas is recycled, so that the utilization rate of the methyl iodide catalyst is improved, and the halogen-containing compounds entering a three-waste system are reduced. Not only reduces the production cost, but also is more beneficial to environmental protection due to lower three-waste discharge.
Drawings
Fig. 1 is a 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 description of the technical contents, the objects and the effects achieved by the present invention, the following description will be given with reference to specific embodiments.
Fig. 1 is a flow chart of an embodiment of the present invention, and as shown in fig. 1, the method for recycling an aromatization catalyst comprises: deslagging the pyrolysis gas subjected to high-temperature aromatization to reduce the risk of pipeline blockage; quenching the cracked gas after deslagging to 180-200 ℃ by pure water; a step of cooling the gas-liquid mixed product from the quenching step by coupling heat exchange with the raw material 3,5, 5-trimethyl-2-cyclohexene-1-one; carrying out alkaline washing and layering on the liquid condensation product from the coupling heat exchange and temperature reduction step to neutralize acidic components and reduce equipment corrosion; carrying out reduced pressure rectification on an organic phase from the alkaline washing layering layer to remove a first part; and (3) carrying out normal pressure rectification on the collected former part to recover the catalyst, and mechanically applying the recovered catalyst to a reaction system.
The pyrolysis gas of high-temperature aromatization is characterized by comprising the following components: 1-5% of 3,5, 5-trimethyl-2-cyclohexene-1-ketone, 77-81% of 3, 5-dimethylphenol, 10-11% of methane gas, 1-5% of m-xylene, 0.5-1.5% of 3, 4-dimethylphenol, 0.2-0.4% of methyl iodide and the like, wherein the temperature of pyrolysis gas for high-temperature aromatization is 500-600 ℃.
The method comprises the following processing procedures: deslagging, quenching, coupling heat exchange, alkaline washing layering, removing the former part and rectifying the former part.
Deslagging: the pyrolysis gas after high-temperature aromatization carries solid particles formed by material decomposition and carbonization, the solid particles are removed from the pyrolysis gas through a cyclone separator, the solid particles and tar substances are prevented from being aggregated and blocking equipment, the diameter of the separated solid particles is greater than 20 mu m, and the pressure drop of the cyclone separator is less than 1 kpa.
Quenching: and (3) carrying out heat exchange on the cracked gas subjected to high-temperature aromatization after deslagging and pure water through a quenching heat exchanger, cooling the cracked gas to a gas-liquid mixed product at 180-200 ℃, and preparing the pure water into low-pressure steam below 0.6MPa to recover heat of the cracked gas.
Coupling heat exchange: and performing coupling heat exchange on the gas-liquid mixed product and the aromatization raw material 3,5, 5-trimethyl-2-cyclohexene-1-ketone for cooling, preheating the raw material, performing gas-liquid separation on the condensation product carrying methane gas at 70-90 ℃ to obtain a liquid condensation product, and performing incineration treatment on the gas-liquid separated methane gas.
Alkali washing and layering: neutralizing the liquid condensation product by using alkali liquor, and preparing solid alkali into the alkali liquor with the concentration of 10-20%, wherein the solid alkali is sodium carbonate and sodium bicarbonate, and preferably sodium carbonate; and (3) mixing alkali liquor with the liquid condensation product according to the mass ratio (1-2): 10, mixing, neutralizing for 10-30 min, controlling the temperature at 65-70 ℃, and neutralizing to obtain a water phase with the pH of 7-8; standing for 30-60 min, layering, and separating the upper layer to obtain an organic phase and the lower layer to obtain the iodine-containing wastewater.
Removing the former parts: rectifying the organic phase under reduced pressure, wherein the pressure is less than or equal to-0.092 MPa, the reflux ratio is 1-3, the first fraction with the boiling point less than or equal to 120 ℃ is extracted from the top of the tower, and the tower bottoms are purified to obtain a 3, 5-dimethylphenol product; the former components comprise methyl iodide, xylene, mesitylene, 3, 4-dimethylphenol and 3, 5-dimethylphenol.
Rectification of the first part: under the condition of normal pressure, the former part of the methyl iodide-containing catalyst is rectified, the reflux ratio is 1-2, fractions with the boiling range of 40-45 ℃ are extracted from the top of the tower, the undecomposed methyl iodide catalyst is recycled, and the recycled catalyst is completely applied to a reaction system.
The following is a further description with reference to specific examples. The high-temperature aromatization referred to in the invention is a prior art, and can refer to patent documents such as US4086862, CN 1583697A and the like, and the specific conditions have no significant influence on the recycling method, and the recycling method of the invention can be adopted as long as methyl iodide is used as a catalyst. In the following examples, unless otherwise specified, aromatization refers to aromatization reaction carried out at 500-600 ℃ with 3,5, 5-trimethyl-2-cyclohexen-1-one as raw material and methyl iodide as catalyst.
Example 1
Continuously pumping 3,5, 5-trimethyl-2-cyclohexene-1-ketone (25.03kg, 181mol) into a shell side (heat exchange area 120 cm)2) Then the mixture and catalyst methyl iodide (250.10g, 1.76mol) enter a reactor together to carry out aromatization reaction under the aromatization reaction condition; the obtained high-temperature pyrolysis gas is subjected to deslagging by a cyclone separator with the thickness of 50mm, and the slag is fed into a quencher (the heat exchange area is 31 cm)2) (ii) a Cooling the quencher by a small amount of hot water, controlling the flow rate of the hot water by a metering pump to stabilize the temperature of a material outlet of the quencher at 183-188 ℃, condensing a product to form a gas-liquid mixture, feeding the gas-liquid mixture into a tube pass of a coupling heat exchanger to preheat the next batch of raw materials 3,5, 5-trimethyl-2-cyclohexene-1-ketone to 135-140 ℃, gradually stabilizing the temperature of the material outlet of the coupling heat exchanger at 73-81 ℃ to form methane-carrying gasThe condensed product was subjected to gas-liquid separation to obtain 21.97kg of a liquid condensed product having a density of 0.966g/cm3And the content of the iodomethane is measured to be 2.23g/L by adopting an external standard method.
Adding a sodium carbonate solution (2.20kg, the mass content is 10%) into the liquid condensation product, stirring and neutralizing, controlling the neutralization temperature at 65-70 ℃, neutralizing for 10min, standing for 30min and then layering; 22.31kg of organic phase and 1.77kg of aqueous phase (pH 7) were obtained. Adding 160.23g of 36% hydrochloric acid into the water phase for acidification, then dropwise adding 30% hydrogen peroxide (100.06g, 0.74mol) into the water phase for reaction for 1 hour, and performing suction filtration to obtain 158.29g of crude iodine with the iodine content of 90.31%.
The organic phase is subjected to vacuum rectification in batches to remove the first part, the height of the tower is 800mm, stainless steel theta net ring packing is adopted, the absolute pressure is 8kPa, the reflux ratio is 3, and the first part with the tower top temperature less than or equal to 118.9 ℃ is collected to obtain 2.34kg of the first part.
The former part is rectified under normal pressure, the tower height is 500mm, stainless steel theta net ring packing is adopted, the reflux ratio is 2, components with the distillation range of 40-45 ℃ are collected at the tower top, catalyst methyl iodide (48.37g) is recovered, the content of methyl iodide is 94.7% by an internal standard method, and 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
Under the aromatization reaction condition, 3,5, 5-trimethyl-2-cyclohexene-1-ketone (25.00kg, 181mol) and catalyst methyl iodide (250.20g, 1.76mol) are fed into a reactor for aromatization reaction. Introducing high-temperature pyrolysis gas into a tower kettle of an alkaline washing tower in a bubbling mode, wherein a sodium carbonate solution (4.00kg, the mass content is 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 solution is gradually boiled, and the temperature of the tower kettle is 108 ℃.
After the reaction is finished, the mixture is layered while the mixture is hot, and 3.28kg of water phase is obtained. Adding 300.09g of 36% hydrochloric acid into the water phase for acidification, then dropwise adding 30% hydrogen peroxide (150.12g, 1.32mol) into the water phase for reaction for 1 hour, and performing suction filtration to obtain 198.00g of crude iodine, wherein the iodine content is 89.91% and the total recovery rate of iodine is 79.57%.
According to the results of the example 1 and the comparative example 1, the total recovery rate of iodine by the method of the application is improved to a certain extent compared with the prior art, and more importantly, about one fifth of the iodine recovered by the method of the invention exists in the form of higher-value methyl iodide, the purity is about 95 percent, and the iodine can be used as a catalyst for application; the recovered iodine is crude iodine with content below 90%, and further purification is required.
Example 2
Continuously pumping 3,5, 5-trimethyl-2-cyclohexene-1-ketone (25.01kg, 181mol) into a shell side (heat exchange area 120 cm)2) Then enters a reactor with catalyst methyl iodide (375.13g, 2.64mol) to carry out aromatization reaction under the aromatization reaction condition; high-temperature pyrolysis gas obtained by aromatization reaction is subjected to slag removal by a cyclone separator with the diameter of 50mm, and the slag is removed and then enters a quencher (the heat exchange area is 31 cm)2) (ii) a The method comprises the following steps of cooling a quencher by a small amount of hot water, controlling the flow rate of the hot water to enable the temperature of a material outlet of the quencher to be kept at 187-195 ℃, condensing a product to form a gas-liquid mixture, enabling the gas-liquid mixture to enter a tube pass of a coupling heat exchanger to preheat the next batch of raw materials 3,5, 5-trimethyl-2-cyclohexene-1-ketone to 134-140 ℃, gradually keeping the temperature of the material outlet of the coupling heat exchanger at 73-85 ℃ to form a condensed product carrying methane gas, carrying 22.07kg of liquid condensed product obtained by gas-liquid separation of the condensed product, and measuring the content of iodomethane to be 3.55g/L by adopting an external standard method.
Adding a sodium carbonate solution (4.41kg, the mass content is 10%) into the liquid condensation product, stirring and neutralizing, controlling the neutralization temperature at 65-70 ℃, neutralizing for 10min, standing for 30min and then layering; 22.74kg of organic phase and 3.63kg of aqueous phase (pH 8) were obtained. Adding 300.11g of 36% hydrochloric acid into the water phase for acidification, then dropwise adding 30% hydrogen peroxide (150.03g, 1.32mol) into the water phase for reaction for 1 hour, and performing suction filtration to obtain 244.70g of crude iodine, wherein the iodine content is 89.84%.
The organic phase is subjected to vacuum rectification in batches to remove the first part, the height of the tower is 800mm, stainless steel theta net ring packing is adopted, the absolute pressure is 6kPa, the reflux ratio is 3, and the first part with the tower top temperature less than or equal to 109.9 ℃ is collected to obtain 2.63kg of the first part.
The former fraction is rectified under normal pressure, the tower height is 500mm, stainless steel theta net ring packing is adopted, the reflux ratio is 2, components with the distillation range of 40-45 ℃ are collected at the tower top, catalyst methyl iodide (77.25g) is recovered, the content of methyl iodide is 94.2% by an internal standard method, and 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
Continuously pumping 3,5, 5-trimethyl-2-cyclohexene-1-ketone (25.00kg, 181mol) into a shell side (heat exchange area 120 cm)2) Then the mixture and catalyst methyl iodide (500.07g, 3.52mol) enter a reactor to carry out aromatization reaction under the aromatization reaction condition; high-temperature pyrolysis gas obtained by aromatization reaction is subjected to slag removal by a cyclone separator with the diameter of 50mm, and the slag is removed and then enters a quencher (the heat exchange area is 31 cm)2) (ii) a The method comprises the following steps of cooling a quencher by a small amount of hot water, controlling the flow rate of the hot water to enable the temperature of a material outlet of the quencher to be stabilized at 186-195 ℃, condensing a product to form a gas-liquid mixture, enabling the gas-liquid mixture to enter a tube pass of a coupling heat exchanger to preheat the next batch of raw materials 3,5, 5-trimethyl-2-cyclohexene-1-ketone to 135-141 ℃, gradually stabilizing the temperature of the material outlet of the coupling heat exchanger to 76-87 ℃ to form a condensed product carrying methane gas, carrying out gas-liquid separation on the condensed product to obtain 22.24kg of a liquid condensed product, and measuring the content of iodomethane to be 4.86g/L by adopting an external standard method.
Adding a sodium carbonate solution (4.48kg, the mass content is 10%) into the liquid condensation product, stirring and neutralizing, controlling the neutralization temperature at 65-70 ℃, neutralizing for 10min, standing for 30min and then layering; 22.80kg of organic phase and 3.81kg of aqueous phase (pH 7) were obtained. Adding 300.11g of 36% hydrochloric acid into the water phase for acidification, then dropwise adding 30% hydrogen peroxide (150.03g, 1.32mol) into the water phase for reaction for 1 hour, and performing suction filtration to obtain 319.09g of crude iodine, wherein the iodine content is 89.92%.
The organic phase is subjected to vacuum rectification in batches to remove the first part, the height of the tower is 800mm, stainless steel theta net ring packing is adopted, the absolute pressure is 6kPa, the reflux ratio is 3, and the first part with the tower top temperature less than or equal to 110 ℃ is collected to obtain 2.50kg of the first part.
The former part is rectified under normal pressure, the tower height is 500mm, stainless steel theta net ring packing is adopted, the reflux ratio is 2, components with the distillation range of 40-45 ℃ are collected at the tower top, catalyst methyl iodide (105.53g) is recovered, the content of methyl iodide is 94.5% by an internal standard method, and 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 the heat carried by the pyrolysis gas of high-temperature aromatization, and simultaneously can recover the catalyst methyl iodide which is not decomposed in the pyrolysis gas, and the recovered catalyst is completely applied to the reaction system. Not only saves energy consumption, but also improves the utilization rate of methyl iodide, reduces production cost, reduces the halogen-containing compounds entering a three-waste system, and has obvious economic benefit and environmental protection significance.