O-methylbenzyl chloride production process and production system thereof

Abstract

The invention discloses an o-methylbenzyl chloride production process and a production system thereof, and relates to the technical field of o-methylbenzyl chloride production, and the process comprises the steps of reaction raw material pretreatment, staged chlorination reaction, in-situ separation and real-time purification, o-methylbenzyl chloride crude product pretreatment, o-methylbenzyl chloride refining treatment, catalyst recovery and environmental protection treatment. The preparation method has the advantages that by improving the uniformity of free radical generation and the good dispersity of the initiator, the free radical generation sites and concentration in the reaction system are more uniform, and the occurrence of local over-reaction areas and incomplete reaction areas is reduced, so that the problems of excessive chlorination and raw material waste are reduced; the temperature, chlorine flow and illumination conditions are accurately controlled in the staged chlorination reaction, so that hydrogen atoms on benzyl carbon atoms are prevented from being continuously substituted, generation of byproducts such as o-methylbenzyl chloride is reduced, the purity of the target product o-methylbenzyl chloride is improved, and the requirement for subsequent multiple distillation or crystallization purification is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of o-methylbenzyl chloride production, in particular to an o-methylbenzyl chloride production process and a production system thereof. Background Art

[0002] The production process of o-methylbenzyl chloride uses o-methyltoluene as raw material and is prepared through a free radical chlorination reaction. The core is to use chlorine gas to replace the hydrogen atoms at the benzyl position under the action of light or an initiator to generate the target product and control polychlorinated by-products.

[0003] For example, publication number CN119500024A discloses a process and system for producing o-methylbenzyl chloride, comprising the following steps: a chlorination section, wherein o-xylene is pumped into an evaporator and heated to a high temperature. The o-xylene in the evaporator vaporizes and enters a chlorination tower. Chlorine gas is introduced into the chlorination tower and reacts with the rising o-xylene gas under visible light catalysis to produce a chlorination reaction. The generated o-methylbenzyl chloride and o-dibenzyl chloride are in liquid form and flow back into the evaporator. The crude benzyl in the evaporator is transferred to a distillation kettle, and the hydrogen chloride gas generated by the reaction enters a hydrogen chloride absorption section.

[0004] However, in the prior art, the hydrogen atoms on the benzyl carbon atoms are easily replaced by chlorine gas due to their high free radical reaction activity, resulting in the formation of by-products such as o-methylbenzyl dichloride, which reduces the purity of the target product and forces subsequent reliance on multiple distillations or crystallizations for purification, driving up costs. At the same time, the uneven distribution of light energy induced by illumination or the poor dispersibility of initiators (such as benzoyl peroxide) lead to differences in the free radical generation sites and concentrations within the reaction system. Local over-reaction areas are prone to exacerbating over-chlorination, while incomplete reaction areas result in waste of raw materials. Summary of the Invention

[0005] The object of the present invention is to provide a production process and a production system of o-methylbenzyl chloride to solve the problems raised by the above background technology.

[0006] To achieve the above object, the present invention provides the following technical solution: a process for producing o-methylbenzyl chloride, comprising the following steps: A1. Pretreatment of reaction raw materials: pretreatment of crude o-methyltoluene, pretreatment of initiator, pretreatment of catalyst and pretreatment of industrial chlorine. The pretreated raw materials are fed into the reactor for reaction; A2. Staged chlorination reaction: First stage initiation and monochlorination: reaction temperature 50-60°C, chlorine flow rate 0.1-0.3 mol / h, optical fiber array illumination wavelength 365nm, light intensity uniformity ≥95%; The second stage of conversion improvement: reaction temperature 60-70℃, chlorine flow rate 0.3-0.5mol / h, turn off the light, and maintain catalyst stirring; The third stage reaction ends: the temperature is ≤70℃, the chlorine supply is stopped, and the circulating cooling water is cooled to 40℃; A3. In-situ separation and real-time purification: Dynamic separation and extraction assist in separating crude o-methylbenzyl chloride and unreacted raw materials during the reaction; A4. Pretreatment of crude o-methylbenzyl chloride: neutralization and deacidification of the crude o-methylbenzyl chloride and washing of the organic phase; A5. Refining treatment of o-methylbenzyl chloride: The pretreated o-methylbenzyl chloride is subjected to atmospheric distillation and reduced pressure distillation respectively; A6. Catalyst recovery: The catalyst residue is distilled through complex precipitation and then calcined for regeneration; A7. Environmental protection treatment: Treat the exhaust gas and wastewater generated during production.

[0007] Preferably, the o-methyltoluene crude product pretreatment, initiator pretreatment, catalyst pretreatment and industrial chlorine pretreatment in A1 include the following steps: A11. Pretreatment of crude o-methyltoluene involves using a molecular sieve adsorption column to deeply remove trace moisture, followed by separation of aromatic impurities through a vacuum distillation tower. The purity of o-methyltoluene is ≥99.9%. A12, initiator pretreatment: Use a shear disperser to disperse the initiator into a nano-scale microemulsion with a particle size of ≤100nm; A13. Catalyst pretreatment: A catalyst dissolving tank is used to stir and heat the solid catalyst to dissolve it in a specific solvent to form a uniform catalyst solution, which is then filtered to remove insoluble impurities. A14. Chlorine buffer tanks are used in industrial chlorine pretreatment to store chlorine and stabilize its pressure and flow.

[0008] Preferably, the staged chlorination reaction in A2 adopts a DCS intelligent control system to set and adjust the reaction parameters in real time. The DCS intelligent control system regulates the o-methylbenzyl chloride chlorination reaction through a closed-loop system of real-time data drive + kinetic model guidance + rapid execution adjustment.

[0009] Preferably, the dynamic separation and extraction-assisted separation of crude o-methylbenzyl chloride and unreacted raw materials in the reaction in A3 comprises the following steps: A31. Establishing dynamic equilibrium of the reaction system: Use online GC detection to monitor the concentration of o-methylbenzyl chloride. When the concentration of o-methylbenzyl chloride reaches 5%-8%, start the in-situ separation system. A32, Distillation-Assisted Dynamic Separation: A pressure of 50-80 kPa is applied to the interior of the reactor to separate unreacted o-methyltoluene, solvent ethylene dichloride, and high o-methylbenzyl chloride. A built-in condenser is installed in the reactor. The vaporized raw materials and solvent are condensed and flow into the raw material temporary storage tank, while o-methylbenzyl chloride and o-methylbenzyl dichloride remain in the reaction liquid at the bottom of the reactor. A33. Extraction-assisted purification: Continuously inject the extractant into the reaction liquid at the bottom of the kettle at a volume ratio of reaction liquid: extractant = 1:0.5-1:1. Stir the reaction liquid and the extractant, and then let it stand to separate into layers. The upper layer containing the crude o-methylbenzyl chloride and the extractant flows into the crude product collection tank, and the lower residual liquid containing a small amount of unreacted raw materials, by-products and catalysts is returned to the reactor for recycling.

[0010] Preferably, the neutralization, deacidification and organic phase washing of the crude o-methylbenzyl chloride in A4 comprises the following steps: A41. Transfer the separated crude o-methylbenzyl chloride to a stirred neutralization reactor and lower the temperature of the crude product to 30-35°C. A42. Add 5%-8% sodium bicarbonate solution to the neutralization reactor at a volume of 1 / 3-1 / 2 of the crude product amount at a rate of ≤5 L / min. Start stirring and react for 10-15 minutes. During this period, monitor the pH value of the aqueous phase with a pH meter and maintain the pH at 7.5-8.5. After the reaction is completed, stop stirring and let it stand for 30-40 minutes to allow the o-methylbenzyl chloride and the extractant to completely separate from the aqueous phase. After observing a clear interface through a sight glass, discharge the lower aqueous phase to a wastewater tank. A43, washing and removing impurities from the organic phase containing o-methylbenzyl chloride and the extractant; A44. Dry and preliminarily purify the organic phase after removing impurities.

[0011] Preferably, the atmospheric distillation and reduced pressure distillation of the pretreated o-methylbenzyl chloride in A5 respectively comprise the following steps: A51. Transfer the pretreated o-methylbenzyl chloride organic phase to an atmospheric distillation kettle with a feed amount not exceeding 2 / 3 of the kettle volume. Add zeolite to the distillation kettle and connect a condenser and a receiver. Heat the raw materials inside the distillation kettle at a rate of 5-10°C / min to the boiling point of the solvent. Control the distillation rate to 1-2 L / h. When the thermometer shows that the distillation temperature is stable at the boiling point of the solvent ±2°C, start collecting the fractions. When the temperature exceeds the boiling point of the solvent by more than 10°C or the distillate continues for 5 minutes without distillation, it is determined that the low-boiling-point components are exhausted. Then stop heating, wait until the temperature in the kettle drops below 60°C, discharge the residual liquid in the kettle to the vacuum distillation feed tank, recover the low-boiling-point solvent to the solvent tank, test the purity and apply the solution. A52. Transfer the residual liquid from atmospheric distillation to a vacuum distillation kettle, connect the vacuum unit, install the distillation column, insert the top thermometer into the top of the distillation column, and connect the condenser and the target product receiver. Turn on the vacuum unit, wait until the system vacuum stabilizes to the set value, and heat up to 120-130°C at a rate of 3-5°C / min. When distillate begins to appear, adjust the heating power to control the distillation rate to 0.5-1L / h, and collect the fraction with a temperature range of ±5°C from the target boiling point. When the top temperature exceeds the target boiling point by more than 15°C or the purity of the distillate is less than 95%, stop heating, close the vacuum valve, and slowly introduce nitrogen to break the vacuum. The collected high-purity o-methylbenzyl chloride is transferred to the finished product storage tank, and the residual liquid in the kettle is regularly discharged to the hazardous waste treatment system. The distillation column is rinsed with a small amount of toluene and then recycled.

[0012] Preferably, the distillation of the catalyst residue in A6, followed by complex precipitation, and then calcination regeneration comprises the following steps: A61. Transfer the catalyst residue after the reaction to a pretreatment tank, filter it through a 200-mesh filter cloth, and transfer the filtrate to a distillation kettle. Start the vacuum system to a vacuum degree of 50-80 kPa. Pass heat transfer oil into the jacket to heat it to ≤120°C. Control the distillation rate to 1-2 L / h. Collect the distillate into a solvent recovery tank, test the purity, and then apply it. When the volume of the residual liquid in the kettle drops to 1 / 5-1 / 10 of the original volume, stop heating. Wait until the temperature drops below 60°C, and discharge the metal concentrate into the precipitation reactor. A62. Add the corresponding complexing agent to the precipitation reaction kettle according to the type of catalyst metal; separate the precipitate using a plate and frame filter press, wash the filter cake with deionized water 2-3 times, transfer the filtrate to the wastewater treatment system, and transfer the filter cake to a drying oven and dry it at 80-100°C for 4-6 hours to a moisture content of <5% to obtain a metal precursor filter cake; A63. Pretreatment before calcination: Crush the dried filter cake into particles less than 2 mm, spread evenly on a corundum crucible with a thickness of ≤2 cm, transfer it into a muffle furnace or rotary kiln, and turn on the inert gas protection; calcine the filter cake that has been pretreated before calcination in stages, then cool and crush the calcined filter cake, and finally regenerate and activate the crushed catalyst.

[0013] Preferably, the treatment of tail gas and wastewater generated during production in A7 comprises the following steps: A71. Use the tail gas treatment system to separate the sources and classify the tail gas. For tail gas containing Cl2, HCl, and organic volatiles, perform primary alkaline solution washing, secondary condensation recovery, and tertiary activated carbon adsorption treatment. The waste gas containing dust, SO2 and NOx is subjected to bag dust removal, wet desulfurization, denitrification and demisting treatment; A72. Use a wastewater treatment system to treat wastewater according to water quality, and neutralize and regulate wastewater containing HCl and Cl⁻ by coagulation and sedimentation; Carry out complex breaking pretreatment and sulfide precipitation treatment on wastewater containing complexing agents and heavy metal ions; Biochemical treatment and deep treatment of wastewater containing COD and salts.

[0014] A system for producing o-methylbenzyl chloride comprises the following: Feeding system: The pre-treated o-methyltoluene, initiator, catalyst solution and industrial chlorine stabilized in the buffer tank are accurately fed into the reactor in the proportion and sequence required by the production process, preparing for the subsequent staged chlorination reaction; Reaction system: The conversion of raw materials is achieved through staged chlorination reaction; Monitoring and control system: Using a DCS intelligent control system, a closed-loop system is constructed with real-time data drive + kinetic model guidance + rapid execution and adjustment. The DCS intelligent control system collects reaction temperature, chlorine flow rate, and pressure parameters in real time, simulates and predicts the reaction process through a kinetic model, and automatically sets and adjusts reaction parameters based on real-time data and model analysis results. During the reaction process, online GC detection is used to monitor the concentration of o-methylbenzyl chloride in real time.

[0015] Discharge system: The discharge system is responsible for the separation, purification, recovery and environmental protection treatment of the materials after the reaction.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. In the present invention, the preparation of the nano-scale microemulsion of the initiator and the formation of a uniform solution of the catalyst in the raw material pretreatment link effectively improve the uniformity of free radical generation. The good dispersibility of the initiator makes the free radical generation sites and concentrations in the reaction system more uniform, reduces the occurrence of local over-reaction zones and incomplete reaction zones, thereby reducing the problems of over-chlorination and raw material waste. Secondly, the precise control of temperature, chlorine flow rate and lighting conditions in the staged chlorination reaction, combined with the real-time adjustment of the DCS intelligent control system, can dynamically adjust the reaction parameters according to the reaction progress, avoid the continuous replacement of hydrogen atoms on the benzyl carbon atom, reduce the generation of by-products such as o-methylbenzyl dichloride, not only improve the purity of the target product o-methylbenzyl chloride, but also reduce the need for subsequent multiple distillations or crystallization purification, reduce production costs, and improve the economic benefits and environmental friendliness of the entire production process; 2. In the present invention, dynamic regulation of the reaction process is achieved through in-situ separation and real-time purification technology. The online GC monitors the concentration of o-methylbenzyl chloride in real time to avoid secondary chlorination of the target product due to excessive retention in the reaction system, suppressing the generation of by-products such as o-methylbenzyl dichloride from the source, and then the unreacted o-methyltoluene and solvent are separated and recycled back to the reactor in time, reducing the residence time of the raw materials in a high-concentration chlorine environment and reducing the probability of continuous substitution reactions; extraction-assisted purification is carried out by continuously injecting an extractant to efficiently separate the crude product and the residual liquid, so that the lower residual liquid containing the catalyst and a small amount of raw materials can be directly reused, which not only improves the raw material utilization rate (reduces waste), but also avoids the formation of local high-concentration reaction zones, balances the free radical concentration in the system, and further suppresses excessive chlorination. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a schematic flow chart of a process for producing o-methylbenzyl chloride according to the present invention; Figure 2 The present invention is a schematic diagram of a system of a process for producing o-methylbenzyl chloride. DETAILED DESCRIPTION

[0018] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the implementation regulations described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of the present invention.

[0019] Example 1: Reference Figure 1 and Figure 2 As shown: A process for producing o-methylbenzyl chloride comprises the following steps: A1. Pretreatment of reaction raw materials: pretreatment of crude o-methyltoluene, pretreatment of initiator, pretreatment of catalyst and pretreatment of industrial chlorine. The pretreated raw materials are fed into the reactor for reaction; The pretreatment of crude o-methyltoluene, initiator pretreatment, catalyst pretreatment and industrial chlorine pretreatment in A1 include the following steps: A11. Pretreatment of crude o-methyltoluene involves using a molecular sieve adsorption column to deeply remove trace moisture, followed by separation of aromatic impurities through a vacuum distillation tower. The purity of o-methyltoluene is ≥99.9%. A12, initiator pretreatment: Use a shear disperser to disperse the initiator into a nano-scale microemulsion with a particle size of ≤100nm; A13. Catalyst pretreatment: A catalyst dissolving tank is used to stir and heat the solid catalyst to dissolve it in a specific solvent to form a uniform catalyst solution, which is then filtered to remove insoluble impurities. A14. Chlorine buffer tanks are used in industrial chlorine pretreatment to store chlorine and stabilize its pressure and flow; A2. Staged chlorination reaction: First stage initiation and monochlorination: reaction temperature 50-60°C, chlorine flow rate 0.1-0.3 mol / h, optical fiber array illumination wavelength 365nm, light intensity uniformity ≥95%; The second stage of conversion improvement: reaction temperature 60-70℃, chlorine flow rate 0.3-0.5mol / h, turn off the light, and maintain catalyst stirring; The third stage reaction ends: the temperature is ≤70℃, the chlorine supply is stopped, and the circulating cooling water is cooled to 40℃; The staged chlorination reaction in A2 uses a DCS intelligent control system to set and adjust the reaction parameters in real time. The DCS intelligent control system regulates the o-methylbenzyl chloride chlorination reaction through a closed-loop system of real-time data drive + kinetic model guidance + rapid execution adjustment.

[0020] In this embodiment, the production of o-methylbenzyl chloride is systematically planned to ensure the efficiency, stability, and product quality of the production process. During the pretreatment of the reaction raw materials, the crude o-methyltoluene is passed through a molecular sieve adsorption column and a vacuum distillation tower to deeply remove moisture and aromatic impurities, providing high-purity raw materials for subsequent reactions. The initiator is processed into a nano-scale microemulsion by a shear disperser to improve dispersibility. The catalyst is dissolved and filtered to form a uniform solution, preventing insoluble impurities from affecting the reaction. The industrial chlorine gas is passed through a buffer tank to stabilize the pressure and flow rate, ensuring stable reaction progress.

[0021] The staged chlorination reaction adopts stage-by-stage control of temperature, chlorine flow rate and light conditions, and uses the DCS intelligent control system to adjust the reaction parameters in real time, making the reaction process more precise and controllable. This staged control and intelligent regulation method helps to reduce the occurrence of side reactions and improve the selectivity and yield of the target product.

[0022] First, the preparation of nano-scale microemulsion of initiator and the formation of uniform solution of catalyst in the raw material pretreatment stage effectively improve the uniformity of free radical generation. The good dispersibility of the initiator makes the free radical generation sites and concentration in the reaction system more uniform, reducing the occurrence of local over-reaction areas and incomplete reaction areas, thereby reducing the problems of over-chlorination and raw material waste.

[0023] Secondly, precise control of temperature, chlorine flow rate, and lighting conditions during the staged chlorination reaction, combined with real-time adjustments by the DCS intelligent control system, dynamically adjusts reaction parameters based on the reaction progress, preventing the continuous replacement of hydrogen atoms on the benzylic carbon atom and reducing the formation of byproducts such as o-methylbenzyl dichloride. This not only improves the purity of the target product, o-methylbenzyl chloride, but also reduces the need for subsequent multiple distillation or crystallization purification, lowering production costs and enhancing the economic efficiency and environmental friendliness of the entire production process.

[0024] Example 2: Figure 1 and Figure 2 As shown, A3, in-situ separation and real-time purification: dynamic separation and extraction assist in separating the crude o-methylbenzyl chloride and unreacted raw materials during the reaction; In A3, the dynamic separation and extraction-assisted separation of crude o-methylbenzyl chloride and unreacted raw materials during the reaction include the following steps: A31. Establishing dynamic equilibrium of the reaction system: Use online GC detection to monitor the concentration of o-methylbenzyl chloride. When the concentration of o-methylbenzyl chloride reaches 5%-8%, start the in-situ separation system. A32, Distillation-Assisted Dynamic Separation: A pressure of 50-80 kPa is applied to the interior of the reactor to separate unreacted o-methyltoluene, solvent ethylene dichloride, and high o-methylbenzyl chloride. A built-in condenser is installed in the reactor. The vaporized raw materials and solvent are condensed and flow into the raw material temporary storage tank, while o-methylbenzyl chloride and o-methylbenzyl dichloride remain in the reaction liquid at the bottom of the reactor. A33, extraction-assisted purification: Continuously inject an extractant into the reaction liquid at the bottom of the kettle at a volume ratio of reaction liquid: extractant = 1:0.5-1:1. Stir the reaction liquid and extractant, then allow to stand for stratification. The upper layer containing the crude o-methylbenzyl chloride and the extractant flows into the crude product collection tank, and the lower residual liquid containing a small amount of unreacted raw materials, by-products, and catalyst is returned to the reactor for recycling; A4. Pretreatment of crude o-methylbenzyl chloride: neutralization and deacidification of the crude o-methylbenzyl chloride and washing of the organic phase; The neutralization, deacidification and organic phase washing of the crude o-methylbenzyl chloride in A4 comprises the following steps: A41. Transfer the separated crude o-methylbenzyl chloride to a stirred neutralization reactor and lower the temperature of the crude product to 30-35°C. A42. Add 5%-8% sodium bicarbonate solution to the neutralization reactor at a volume of 1 / 3-1 / 2 of the crude product amount at a rate of ≤5 L / min. Start stirring and react for 10-15 minutes. During this period, monitor the pH value of the aqueous phase with a pH meter and maintain the pH at 7.5-8.5. After the reaction is completed, stop stirring and let it stand for 30-40 minutes to allow the o-methylbenzyl chloride and the extractant to completely separate from the aqueous phase. After observing a clear interface through a sight glass, discharge the lower aqueous phase to a wastewater tank. A43, washing and removing impurities from the organic phase containing o-methylbenzyl chloride and the extractant; A44, drying and preliminarily purifying the organic phase after the impurities are removed; A5. Refining treatment of o-methylbenzyl chloride: The pretreated o-methylbenzyl chloride is subjected to atmospheric distillation and reduced pressure distillation respectively; In A5, the pretreated o-methylbenzyl chloride is subjected to atmospheric distillation and reduced pressure distillation respectively, comprising the following steps: A51. Transfer the pretreated o-methylbenzyl chloride organic phase to an atmospheric distillation kettle with a feed amount not exceeding 2 / 3 of the kettle volume. Add zeolite to the distillation kettle and connect a condenser and a receiver. Heat the raw materials inside the distillation kettle at a rate of 5-10°C / min to the boiling point of the solvent. Control the distillation rate to 1-2 L / h. When the thermometer shows that the distillation temperature is stable at the boiling point of the solvent ±2°C, start collecting the fractions. When the temperature exceeds the boiling point of the solvent by more than 10°C or the distillate continues for 5 minutes without distillation, it is determined that the low-boiling-point components are exhausted. Then stop heating, wait until the temperature in the kettle drops below 60°C, discharge the residual liquid in the kettle to the vacuum distillation feed tank, recover the low-boiling-point solvent to the solvent tank, test the purity and apply the solution. A52. Transfer the atmospheric distillation residue to a vacuum distillation kettle, connect a vacuum unit, install a distillation column, insert a tower top thermometer into the top of the distillation column, and connect a condenser and a target product receiver. Start the vacuum unit, wait until the system vacuum stabilizes to the set value, and heat to 120-130°C at a rate of 3-5°C / min. When distillate begins to appear, adjust the heating power to control the distillation rate to 0.5-1 L / h, and collect the fraction within the temperature range of the target boiling point ±5°C. When the tower top temperature exceeds the target boiling point by more than 15°C or the distillate purity is less than 95%, stop heating, close the vacuum valve, and slowly introduce nitrogen to break the vacuum. Transfer the collected high-purity o-methylbenzyl chloride to a finished product storage tank, regularly discharge the residual liquid in the kettle to the hazardous waste treatment system, and rinse the distillation column with a small amount of toluene for recycling. A6. Catalyst recovery: The catalyst residue is distilled through complex precipitation and then calcined for regeneration; In A6, the catalyst residue is distilled and precipitated, and then calcined and regenerated, which includes the following steps: A61. Transfer the catalyst residue after the reaction to a pretreatment tank, filter it through a 200-mesh filter cloth, and transfer the filtrate to a distillation kettle. Start the vacuum system to a vacuum degree of 50-80 kPa. Pass heat transfer oil into the jacket to heat it to ≤120°C. Control the distillation rate to 1-2 L / h. Collect the distillate into a solvent recovery tank, test the purity, and then apply it. When the volume of the residual liquid in the kettle drops to 1 / 5-1 / 10 of the original volume, stop heating. Wait until the temperature drops below 60°C, and discharge the metal concentrate into the precipitation reactor. A62. Add the corresponding complexing agent to the precipitation reaction kettle according to the type of catalyst metal; separate the precipitate using a plate and frame filter press, wash the filter cake with deionized water 2-3 times, transfer the filtrate to the wastewater treatment system, and transfer the filter cake to a drying oven and dry it at 80-100°C for 4-6 hours to a moisture content of <5% to obtain a metal precursor filter cake; A63. Pre-calcination pretreatment: Crush the dried filter cake to a particle size of less than 2 mm, spread it evenly on a corundum crucible with a thickness of ≤2 cm, and transfer it to a muffle furnace or rotary kiln under inert gas protection; calcine the filter cake after pre-calcination in stages, cool and crush the calcined filter cake, and finally regenerate and activate the crushed catalyst; A7. Environmental protection treatment: Treat the exhaust gas and wastewater generated during production.

[0025] The treatment of tail gas and wastewater generated during production in A7 includes the following steps: A71. Use the tail gas treatment system to separate the sources and classify the tail gas. For tail gas containing Cl2, HCl, and organic volatiles, perform primary alkaline solution washing, secondary condensation recovery, and tertiary activated carbon adsorption treatment. The waste gas containing dust, SO2 and NOx is subjected to bag dust removal, wet desulfurization, denitrification and demisting treatment; A72. Use a wastewater treatment system to treat wastewater according to water quality, and neutralize and regulate wastewater containing HCl and Cl⁻ by coagulation and sedimentation; Carry out complex breaking pretreatment and sulfide precipitation treatment on wastewater containing complexing agents and heavy metal ions; Biochemical treatment and deep treatment of wastewater containing COD and salts.

[0026] In this embodiment, dynamic regulation of the reaction process is achieved through in-situ separation and real-time purification technology. The concentration of o-methylbenzyl chloride is monitored in real time by online GC. When the concentration reaches 5%-8%, the separation system is activated to prevent the target product from being excessively retained in the reaction system and causing secondary chlorination, thereby suppressing the generation of by-products such as o-methylbenzyl dichloride from the source.

[0027] Distillation-assisted dynamic separation uses 50-80kPa pressure control and a built-in condenser to promptly separate unreacted o-methyltoluene and solvent and recycle them back to the reactor, reducing the residence time of the raw materials in a high-concentration chlorine environment and reducing the probability of continuous substitution reactions; Extraction-assisted purification efficiently separates the crude product from the residual liquid by continuously injecting the extractant (volume ratio 1:0.5-1:1), so that the lower residual liquid containing the catalyst and a small amount of raw materials can be directly reused. This not only improves the utilization rate of raw materials (reduces waste), but also avoids the formation of local high-concentration reaction zones, balances the free radical concentration in the system, and further inhibits over-chlorination.

[0028] In the subsequent refining process, atmospheric-reduced pressure distillation is used to separate the low-boiling-point solvent and the target product in stages, and the distillation temperature and rate are precisely controlled (for example, reduced pressure distillation collects the fraction with the target boiling point ±5°C), ensuring an increased yield of high-purity o-methylbenzyl chloride (≥95%) in one step, reducing the energy consumption and cost of traditional processes that rely on multiple distillations.

[0029] To address the challenges of catalyst waste and three wastes treatment in traditional processes, the solution achieves circular economy and green production through catalyst regeneration technology and graded environmentally friendly treatment: In the catalyst recovery process, after the residual liquid is distilled and concentrated, complexed and precipitated, and calcined in stages, the recovery rate of the active components of the metal catalyst (such as iron and copper) reaches over 90%. The regenerated catalyst can be directly reused in the reaction (such as the V3 catalyst solution tank), significantly reducing the catalyst consumption cost. Environmental protection treatment is carried out according to the characteristics of different pollutants: tail gas undergoes three-stage treatment including alkaline washing (to remove Cl2 and HCl), condensation (to recover organic matter), and activated carbon adsorption (to remove VOCs), with an emission compliance rate of ≥98%; wastewater is classified according to water quality and treated through neutralization and precipitation (to treat acidic wastewater), complex desulfurization (to remove heavy metals), and biochemical + deep treatment (to degrade COD and salts), achieving a reclaimed water reuse rate of ≥30% and a salt recovery rate of ≥85%, thereby reducing the emission intensity of the "three wastes" from the source and avoiding the surge in end-of-pipe treatment costs caused by the high pollution load in traditional processes.

[0030] Example 3: A system for producing o-methylbenzyl chloride, comprising the following: Feeding system: The feeding system delivers pretreated o-methyltoluene, initiator nano-microemulsion, catalyst solution and industrial chlorine stabilized by a buffer tank to the reactor in strict accordance with the established sequence and proportion, relying on high-precision metering pumps, mass flow meters and automatic control devices. Through nitrogen sealing to prevent oxidation, interlocking to prevent leakage, dynamic calibration to ensure accuracy and other measures, the raw materials are ensured to enter the reactor accurately, laying a stable foundation for the staged chlorination reaction.

[0031] Reaction System: The reaction system utilizes a three-stage temperature-controlled reactor as its core. By precisely controlling temperature, chlorine flow rate, and illumination conditions, the system drives the conversion of raw materials in stages: In the first stage, at 50-60°C, the initiator is activated by light from an optical fiber array, and a low-flow chlorine flow initiates the benzyl monochlorination reaction; in the second stage, the temperature is raised to 60-70°C, the illumination is turned off, and the chlorine flow rate is increased, with the catalyst continuously driving the chlorination process; in the third stage, the temperature is controlled at ≤70°C, the chlorine flow is stopped, and the temperature is rapidly lowered to terminate the reaction. The system is equipped with an anchor agitator to enhance mass transfer. Combined with a DCS intelligent control system to collect parameters such as temperature and pressure in real time, the system dynamically optimizes the reaction process using a kinetic model. Simultaneously, an online gas chromatograph monitors the concentration of o-methylbenzyl chloride to ensure efficient conversion of raw materials to the target product while suppressing side reactions.

[0032] Monitoring and control system: Using a DCS intelligent control system, a closed-loop system is constructed with real-time data drive + kinetic model guidance + rapid execution and adjustment. The DCS intelligent control system collects reaction temperature, chlorine flow rate, and pressure parameters in real time, simulates and predicts the reaction process through a kinetic model, and automatically sets and adjusts reaction parameters based on real-time data and model analysis results. During the reaction process, online GC detection is used to monitor the concentration of o-methylbenzyl chloride in real time.

[0033] Discharge system: The discharge system is responsible for the separation, purification, recovery and environmental protection treatment of the materials after the reaction.

[0034] Working Principle of the Present Invention: The o-methylbenzyl chloride production process of the present invention covers multiple key steps, including pretreatment of reaction raw materials, staged chlorination reaction, in-situ separation and purification, crude product pretreatment, refining treatment, catalyst recovery, and environmental treatment. During the reaction raw material pretreatment stage, crude o-methyltoluene, initiator, catalyst, and industrial chlorine are treated separately to ensure the quality of the raw materials fed into the reaction. The staged chlorination reaction is carried out in stages under the precise control of the DCS intelligent control system to improve reaction efficiency and selectivity. The in-situ separation and real-time purification steps dynamically separate the crude o-methylbenzyl chloride and unreacted raw materials during the reaction process, thereby improving raw material utilization.

[0035] The crude product then undergoes pretreatment, including neutralization, deacidification, washing, and drying, before being refined through atmospheric and vacuum distillation to yield high-purity o-methylbenzyl chloride. The catalyst residue is then recycled through distillation, complex precipitation, and calcination, reducing production costs.

[0036] Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments, or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A process for producing o-methylbenzyl chloride, characterized in that: The following steps are involved: A1. Pretreatment of reaction raw materials: pretreatment of crude o-methyltoluene, pretreatment of initiator, pretreatment of catalyst and pretreatment of industrial chlorine. The pretreated raw materials are fed into the reactor for reaction; A2. Staged chlorination reaction: First stage initiation and monochlorination: reaction temperature 50-60°C, chlorine flow rate 0.1-0.3 mol / h, optical fiber array illumination wavelength 365nm, light intensity uniformity ≥95%; The second stage of conversion improvement: reaction temperature 60-70℃, chlorine flow rate 0.3-0.5mol / h, turn off the light, and maintain catalyst stirring; The third stage reaction ends: the temperature is ≤70℃, the chlorine supply is stopped, and the circulating cooling water is cooled to 40℃; A3. In-situ separation and real-time purification: Dynamic separation and extraction assist in separating crude o-methylbenzyl chloride and unreacted raw materials during the reaction; A4. Pretreatment of crude o-methylbenzyl chloride: neutralization and deacidification of the crude o-methylbenzyl chloride and washing of the organic phase; A5. Refining treatment of o-methylbenzyl chloride: The pretreated o-methylbenzyl chloride is subjected to atmospheric distillation and reduced pressure distillation respectively; A6. Catalyst recovery: The catalyst residue is distilled through complex precipitation and then calcined for regeneration; A7. Environmental protection treatment: Treat the exhaust gas and wastewater generated during production.

2. A process for producing o-methylbenzyl chloride according to claim 1, characterized in that: The pretreatment of crude o-methyltoluene, initiator pretreatment, catalyst pretreatment and industrial chlorine pretreatment in A1 include the following steps: A11. Pretreatment of crude o-methyltoluene involves using a molecular sieve adsorption column to deeply remove trace moisture, followed by separation of aromatic impurities through a vacuum distillation tower. The purity of o-methyltoluene is ≥99.9%. A12, initiator pretreatment: Use a shear disperser to disperse the initiator into a nano-scale microemulsion with a particle size of ≤100nm; A13. Catalyst pretreatment: A catalyst dissolving tank is used to stir and heat the solid catalyst to dissolve it in a specific solvent to form a uniform catalyst solution, which is then filtered to remove insoluble impurities. A14. Chlorine buffer tanks are used in industrial chlorine pretreatment to store chlorine and stabilize its pressure and flow.

3. A process for producing o-methylbenzyl chloride according to claim 2, characterized in that: The staged chlorination reaction in A2 uses a DCS intelligent control system to set and adjust the reaction parameters in real time. The DCS intelligent control system regulates the o-methylbenzyl chloride chlorination reaction through a closed-loop system of real-time data drive + kinetic model guidance + rapid execution adjustment.

4. A process for producing o-methylbenzyl chloride according to claim 3, characterized in that: In A3, the dynamic separation and extraction-assisted separation of crude o-methylbenzyl chloride and unreacted raw materials during the reaction include the following steps: A31. Establishing dynamic equilibrium of the reaction system: Use online GC detection to monitor the concentration of o-methylbenzyl chloride. When the concentration of o-methylbenzyl chloride reaches 5%-8%, start the in-situ separation system. A32, Distillation-Assisted Dynamic Separation: A pressure of 50-80 kPa is applied to the interior of the reactor to separate unreacted o-methyltoluene, solvent ethylene dichloride, and high o-methylbenzyl chloride. A built-in condenser is installed in the reactor. The vaporized raw materials and solvent are condensed and flow into the raw material temporary storage tank, while o-methylbenzyl chloride and o-methylbenzyl dichloride remain in the reaction liquid at the bottom of the reactor. A33. Extraction-assisted purification: Continuously inject the extractant into the reaction liquid at the bottom of the kettle at a volume ratio of reaction liquid: extractant = 1:0.5-1:

1. Stir the reaction liquid and the extractant, and then let it stand to separate into layers. The upper layer containing the crude o-methylbenzyl chloride and the extractant flows into the crude product collection tank, and the lower residual liquid containing a small amount of unreacted raw materials, by-products and catalysts is returned to the reactor for recycling.

5. A process for producing o-methylbenzyl chloride according to claim 4, characterized in that: The neutralization, deacidification and organic phase washing of the crude o-methylbenzyl chloride in A4 comprises the following steps: A41. Transfer the separated crude o-methylbenzyl chloride to a stirred neutralization reactor and lower the temperature of the crude product to 30-35°C. A42. Add 5%-8% sodium bicarbonate solution to the neutralization reactor at a volume of 1 / 3-1 / 2 of the crude product amount at a rate of ≤5 L / min. Start stirring and react for 10-15 minutes. During this period, monitor the pH value of the aqueous phase with a pH meter and maintain the pH at 7.5-8.

5. After the reaction is completed, stop stirring and let it stand for 30-40 minutes to allow the o-methylbenzyl chloride and the extractant to completely separate from the aqueous phase. After observing a clear interface through a sight glass, discharge the lower aqueous phase to a wastewater tank. A43, washing and removing impurities from the organic phase containing o-methylbenzyl chloride and the extractant; A44. Dry and preliminarily purify the organic phase after removing impurities.

6. A process for producing o-methylbenzyl chloride according to claim 5, characterized in that: In A5, the pretreated o-methylbenzyl chloride is subjected to atmospheric distillation and reduced pressure distillation respectively, comprising the following steps: A51. Transfer the pretreated o-methylbenzyl chloride organic phase to an atmospheric distillation kettle with a feed amount not exceeding 2 / 3 of the kettle volume. Add zeolite to the distillation kettle and connect a condenser and a receiver. Heat the raw materials inside the distillation kettle at a rate of 5-10°C / min to the boiling point of the solvent. Control the distillation rate to 1-2 L / h. When the thermometer shows that the distillation temperature is stable at the boiling point of the solvent ±2°C, start collecting the fractions. When the temperature exceeds the boiling point of the solvent by more than 10°C or the distillate continues for 5 minutes without distillation, it is determined that the low-boiling-point components are exhausted. Then stop heating, wait until the temperature in the kettle drops below 60°C, discharge the residual liquid in the kettle to the vacuum distillation feed tank, recover the low-boiling-point solvent to the solvent tank, test the purity and apply the solution. A52. Transfer the residual liquid from atmospheric distillation to a vacuum distillation kettle, connect the vacuum unit, install the distillation column, insert the top thermometer into the top of the distillation column, and connect the condenser and the target product receiver. Turn on the vacuum unit, wait until the system vacuum stabilizes to the set value, and heat up to 120-130°C at a rate of 3-5°C / min. When distillate begins to appear, adjust the heating power to control the distillation rate to 0.5-1L / h, and collect the fraction with a temperature range of ±5°C from the target boiling point. When the top temperature exceeds the target boiling point by more than 15°C or the purity of the distillate is less than 95%, stop heating, close the vacuum valve, and slowly introduce nitrogen to break the vacuum. The collected high-purity o-methylbenzyl chloride is transferred to the finished product storage tank, and the residual liquid in the kettle is regularly discharged to the hazardous waste treatment system. The distillation column is rinsed with a small amount of toluene and then recycled.

7. A process for producing o-methylbenzyl chloride according to claim 6, characterized in that: In A6, the catalyst residue is distilled and precipitated, and then calcined and regenerated, which includes the following steps: A61. Transfer the catalyst residue after the reaction to a pretreatment tank, filter it through a 200-mesh filter cloth, and transfer the filtrate to a distillation kettle. Start the vacuum system to a vacuum degree of 50-80 kPa. Pass heat transfer oil into the jacket to heat it to ≤120°C. Control the distillation rate to 1-2 L / h. Collect the distillate into a solvent recovery tank, test the purity, and then apply it. When the volume of the residual liquid in the kettle drops to 1 / 5-1 / 10 of the original volume, stop heating. Wait until the temperature drops below 60°C, and discharge the metal concentrate into the precipitation reactor. A62. Add the corresponding complexing agent to the precipitation reaction kettle according to the type of catalyst metal; separate the precipitate using a plate and frame filter press, wash the filter cake with deionized water 2-3 times, transfer the filtrate to the wastewater treatment system, and transfer the filter cake to a drying oven and dry it at 80-100°C for 4-6 hours to a moisture content of <5% to obtain a metal precursor filter cake; A63. Pretreatment before calcination: Crush the dried filter cake into particles less than 2 mm, spread evenly on a corundum crucible with a thickness of ≤2 cm, transfer it into a muffle furnace or rotary kiln, and turn on the inert gas protection; calcine the filter cake that has been pretreated before calcination in stages, then cool and crush the calcined filter cake, and finally regenerate and activate the crushed catalyst.

8. A process for producing o-methylbenzyl chloride according to claim 7, characterized in that: The treatment of tail gas and wastewater generated during production in A7 includes the following steps: A71. Use the tail gas treatment system to separate the sources and classify the tail gas. For tail gas containing Cl2, HCl, and organic volatiles, perform primary alkaline solution washing, secondary condensation recovery, and tertiary activated carbon adsorption treatment. The waste gas containing dust, SO2 and NOx is subjected to bag dust removal, wet desulfurization, denitrification and demisting treatment; A72. Use a wastewater treatment system to treat wastewater according to water quality, and neutralize and regulate wastewater containing HCl and Cl⁻ by coagulation and sedimentation; Carry out complex breaking pretreatment and sulfide precipitation treatment on wastewater containing complexing agents and heavy metal ions; Biochemical treatment and deep treatment of wastewater containing COD and salts.

9. A system for producing o-methylbenzyl chloride, characterized in that: The process for producing o-methylbenzyl chloride according to claim 8 is used, comprising the following steps: Feeding system: The pre-treated o-methyltoluene, initiator, catalyst solution and industrial chlorine stabilized in the buffer tank are accurately fed into the reactor in the proportion and sequence required by the production process, preparing for the subsequent staged chlorination reaction; Reaction system: The conversion of raw materials is achieved through staged chlorination reaction; Monitoring and control system: Using a DCS intelligent control system, a closed-loop system is constructed that combines real-time data drive, kinetic model guidance, and rapid execution and adjustment. The DCS intelligent control system collects reaction temperature, chlorine flow rate, and pressure parameters in real time, simulates and predicts the reaction process through a kinetic model, and automatically sets and adjusts reaction parameters based on real-time data and model analysis results. During the reaction, online GC detection is used to monitor the concentration of o-methylbenzyl chloride in real time. Discharge system: The discharge system is responsible for the separation, purification, recovery and environmental protection treatment of the materials after the reaction.

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