Ethyl acetate catalytic synthesis process based on phase transfer regulation

Abstract

This invention relates to the field of acyclic compound synthesis technology and discloses a phase transfer-controlled catalytic synthesis process for ethyl acetate, comprising: spraying a catalytic extract containing ionic liquid, inorganic salt, and block copolymer hydrogel into a countercurrent reaction separation space, causing acetic acid and ethanol to react in contact on the surface of a structured packing material; controlling the gas velocity in the gas-phase column to generate a shear force field, maintaining the liquid film dispersed phase at the microscale and inhibiting polymer aggregation; utilizing the solvation effect of the copolymer to transfer the reaction-generated water in situ to the hydrogel phase, breaking the thermodynamic equilibrium and obtaining ethyl acetate from the top. This invention maintains the interfacial shielding layer through the dynamic counteraction between the flow field kinetic energy and the salting-out tendency, achieving microscopic decoupling of the catalytic and dehydration processes, relieving the thermodynamic inhibition of esterification by water, and improving the conversion depth while ensuring the long-term activity of the catalyst.

Description

Technical Field

[0001] This invention belongs to the field of acyclic compound synthesis technology, and particularly relates to an ethyl acetate catalytic synthesis process based on phase transfer regulation. Background Technology

[0002] Currently, in the industrial production of acyclic esters, the esterification reaction of acetic acid and ethanol under the action of protic acid catalysts is the mainstream route for synthesizing ethyl acetate. Due to the typical thermodynamic reversibility of the esterification reaction, the water generated in the reaction accumulates continuously in the system, causing the reverse reaction rate to increase with the conversion rate, which restricts the reaction equilibrium. At the same time, the generated ethyl acetate, raw material ethanol, and water easily form a ternary azeotrope in the system. This thermodynamic azeotropic constraint makes it more difficult for the product to be removed from the reaction center. As a result, the industrial production adopts a process architecture of high reflux ratio operation and multiple distillation columns in series, resulting in large system heat energy consumption and large-scale equipment investment.

[0003] However, when introducing high concentrations of inorganic salts into a reactive distillation system to couple reaction and separation, the system faces a fundamental limitation: the incompatibility between thermodynamically deboiling reagents and kinetic catalytic reagents at the microscopic level. Strong electrolyte salts dissociate into metal cations with high hydration energies in the liquid phase. These ions readily compete for coordination or electrostatically shield the acidic active sites of the catalyst, leading to a decrease in the efficiency of the catalytic active centers or even deactivation. This microscopic antagonism presents a technical trade-off in simultaneously achieving efficient catalysis and in-situ water stripping within a single reaction space. Existing processes typically require separating the reaction zone and salting-out extraction at the macroscopic equipment scale. For example, [the text abruptly ends here]. Chinese invention patent CN101255111B discloses a method for synthesizing ethyl acetate by continuous esterification reaction distillation catalyzed by ionic liquid. It utilizes acidic ionic liquid to improve catalytic selectivity and enhances water removal by increasing the proportion of acetic acid at the bottom of the reactor and refluxing crude ester. However, it still falls within the scope of macroscopic thermodynamic equilibrium regulation. When facing a dehydration environment with a high salt precipitation tendency, this type of process lacks a microscopic isolation mechanism for catalytic active sites, which can easily induce metal ions to permeate and poison the acidic centers of the ionic liquid. At the same time, it lacks dynamic control methods for the hydrodynamic instability of the multiphase system on the packing surface, making it difficult to achieve sub-μm-level directional water permeation and capture while ensuring catalytic activity.

[0004] Therefore, the technical problem to be solved by this invention is how to construct a microscopic shielding mechanism that can resist electrolyte interference within a single countercurrent reaction separation space, so as to maintain catalytic activity while achieving directional water infiltration and capture and phase equilibrium shift. Summary of the Invention

[0005] This invention provides a phase-transfer-regulated catalytic synthesis process for ethyl acetate, comprising the following steps: Step S101: Spray a catalytic-extraction multiphase flow liquid onto the top of the countercurrent reaction separation space. The catalytic-extraction multiphase flow liquid contains, by weight, 15 to 25 parts of... Ionic liquid, CaCl2 in a molar ratio of 0.2:1 to 0.5:1 relative to the ionic liquid, and a phase transfer hydrogel matrix composed of a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and deionized water; Step S102: The mixture of acetic acid and ethanol is introduced into the middle of the countercurrent reaction separation space, so that the mixture of acetic acid and ethanol comes into contact with the catalytic-extraction multiphase flow liquid on the surface of the structured packing. Step S103: Control the gas velocity in the empty tower within the countercurrent reaction separation space to be in the range of 0.8 m / s to 1.5 m / s. Use the shear force field generated by the gas phase to maintain the particle size of the liquid film dispersed phase on the surface of the structured packing at 200 nm to 500 nm, thereby inhibiting the polymerization of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. In step S104, the water generated by the esterification reaction is transferred to the phase transfer hydrogel matrix by the solvation effect of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer on water molecules, and ethyl acetate is obtained from the top of the countercurrent reaction separation space.

[0006] Preferably, step S101 includes the following steps: selecting a copolymer with a weight-average molecular weight of 8,000 to 12,000 and a mass ratio of ethylene oxide segment to propylene oxide segment of 3:7 to 4:6 as a ethylene oxide-propylene oxide-ethylene oxide triblock copolymer, and controlling the mass percentage concentration of the ethylene oxide-propylene oxide-ethylene oxide triblock copolymer in the phase transfer hydrogel matrix to be 2% to 5%.

[0007] Preferably, step S103 includes the step of: using the shear force field generated in the gas phase to cause the catalytic-extraction multiphase fluid to flow in a specific surface area of ​​250 m². 2 / m 3 up to 500m 2 / m 3 A liquid film is formed on the surface of the regular filler, and the thickness of the interface shielding layer is maintained at 200nm to 500nm.

[0008] Preferably, step S102 includes the following steps: controlling the mixing of acetic acid and ethanol at a molar ratio of 1:1.1 to 1:1.3 and then introducing them, and controlling the reaction temperature of the esterification reaction in the countercurrent reaction separation space at 85°C to 115°C, and the reaction pressure at atmospheric pressure.

[0009] Preferably, after step S104, the following steps are also included: Step S105: Collect the reaction waste liquid from the bottom of the countercurrent reaction separation space and measure the mass percentage concentration of water in the reaction waste liquid; Step S106: Calculate the circulation regeneration rate of the reaction waste liquid entering the regeneration unit based on the mass percentage concentration and the preset total circulation flow rate of the catalytic-extraction multiphase flow liquid.

[0010] Preferably, step S101 further includes the step of: adjusting the dynamic viscosity of the catalytic-extraction multiphase flow liquid at 100°C to 15 mPa·s to 35 mPa·s, and controlling the surface tension of the catalytic-extraction multiphase flow liquid on the structured packing surface to be not less than 45 mN / m.

[0011] Preferably, when obtaining ethyl acetate in step S104, the mass purity of ethyl acetate at the top of the countercurrent reaction separation space is controlled to be no less than 98.5%, and the single-pass conversion rate of acetic acid is controlled to be no less than 97%.

[0012] Preferably, the regeneration unit includes a stripping tower, and after step S106, the following steps are included: introducing the reaction waste liquid into the stripping tower, destroying the hydration structure of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and water molecules at a stripping temperature of 130°C to 150°C, and returning the resulting regenerated liquid to step S101 after removing the water.

[0013] Preferably, after step S106, the step is: feeding back the latent heat of vapor condensation generated at the top of the stripping tower to step S102 via a heat pump circulation path to preheat the mixture of acetic acid and ethanol.

[0014] Preferably, the local inorganic salt dissolution balance in the countercurrent reaction separation space is adjusted by the side-line water supply pipeline, and the real-time solubility of CaCl2 is determined based on the real-time monitored liquid phase refractive index data, so as to control the real-time concentration of CaCl2 to be maintained below 95% of its saturation concentration curve.

[0015] Compared with existing technologies, the ethyl acetate catalytic synthesis process based on phase transfer regulation of this invention has the following advantages: 1. In the ethyl acetate catalytic synthesis process, a dynamic non-ionic interfacial shielding layer is constructed between the catalytic phase and the extraction phase by distributing a non-sulfuric acid bifunctional catalyst and a chemical phase regulator in the countercurrent reaction separation space, combined with the thermally induced dehydration phase transition of the polyoxyethylene-polyoxypropylene block copolymer at a temperature above its cloud point. This shielding layer utilizes the steric hindrance effect on hydrated metal ion clusters to block the competitive coordination of electrolyte ions to catalytic active sites, maintain the catalytic efficiency of Brønsted acid sites, achieve incompatible decoupling of the reaction and dehydration processes at the microscopic level, and ensure the long-term stability of the catalytic system.

[0016] 2. By utilizing the rising gas phase kinetic energy in the reaction section and the salting-out cohesion of the block copolymer, an anti-dissipation equilibrium is constructed. The high-frequency gas-liquid shear stress generated on the surface of the structured packing by the empty tower gas velocity in the range of 0.8 to 1.5 m / s forcibly inhibits the macroscopic polymerization and gelation scaling tendency of polymer macromolecules, maintaining the interface shielding layer in a dynamic stable state at the sub-μm level. This ensures efficient mass transfer while avoiding blockage of the reaction channel, thus ensuring the mechanical reliability of the process under continuous industrial operation conditions.

[0017] 3. Based on the specific hydration effect of chemical phase modifiers on water molecules, the activity coefficients of each component in the reaction system are changed, inducing a thermodynamic phase equilibrium shift in the ternary azeotropic system formed by ethanol, water and ethyl acetate. This allows the water generated in the reaction to be captured in situ and removed from the reaction center the instant it is produced, fundamentally eliminating the inhibition of water accumulation on the forward esterification reaction, and making the single-pass conversion rate of acetic acid approach the thermodynamic limit. Attached Figure Description

[0018] Figure 1 This is a flowchart of the process implementation steps and phase parameter control of the present invention; Figure 2 This is a logic diagram of the micro-interface shielding and phase balance displacement principle of the present invention. Detailed Implementation

[0019] The technical solutions of the embodiments of this application will be clearly described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of this application are within the scope of protection of this application.

[0020] It should be noted that all directional and positional terms used in this invention, such as: up, down, left, right, front, back, vertical, horizontal, inner, outer, top, bottom, transverse, longitudinal, center, etc., are only used to explain the relative positional relationship and connection between components in a specific state (as shown in the accompanying drawings). They are only for the convenience of describing this invention and do not require that this invention be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention. In addition, the descriptions of "first," "second," etc., in this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the terms installation, connection, and linking should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections; they can refer to direct connections or indirect connections through an intermediate medium; they can refer to the internal connection of two components. For those skilled in the art, the specific meaning of the above terms in this invention can be understood according to the specific circumstances.

[0022] In the description of this specification, references to the terms "an embodiment," "some embodiments," "illustrative embodiments," "examples," "specific examples," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example, and the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0023] A phase-transfer-regulated catalytic synthesis process for ethyl acetate includes the following steps: Step S101: Spray a catalytic-extraction multiphase flow liquid onto the top of the countercurrent reaction separation space. The catalytic-extraction multiphase flow liquid contains, by weight, 15 to 25 parts of... Ionic liquid, CaCl2 in a molar ratio of 0.2:1 to 0.5:1 relative to the ionic liquid, and a phase transfer hydrogel matrix composed of a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and deionized water; Step S102: The mixture of acetic acid and ethanol is introduced into the middle of the countercurrent reaction separation space, so that the mixture of acetic acid and ethanol comes into contact with the catalytic-extraction multiphase flow liquid on the surface of the structured packing. Step S103: Control the gas velocity in the empty tower within the countercurrent reaction separation space to be in the range of 0.8 m / s to 1.5 m / s. Use the shear force field generated by the gas phase to maintain the particle size of the liquid film dispersed phase on the surface of the structured packing at 200 nm to 500 nm, thereby inhibiting the polymerization of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. In step S104, the water generated by the esterification reaction is transferred to the phase transfer hydrogel matrix by the solvation effect of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer on water molecules, and ethyl acetate is obtained from the top of the countercurrent reaction separation space.

[0024] Preferably, step S101 includes the following steps: selecting a copolymer with a weight-average molecular weight of 8,000 to 12,000 and a mass ratio of ethylene oxide segment to propylene oxide segment of 3:7 to 4:6 as a ethylene oxide-propylene oxide-ethylene oxide triblock copolymer, and controlling the mass percentage concentration of the ethylene oxide-propylene oxide-ethylene oxide triblock copolymer in the phase transfer hydrogel matrix to be 2% to 5%.

[0025] Preferably, step S103 includes the step of: using the shear force field generated in the gas phase to cause the catalytic-extraction multiphase fluid to flow in a specific surface area of ​​250 m². 2 / m 3 up to 500m 2 / m 3 A liquid film is formed on the surface of the regular filler, and the thickness of the interface shielding layer is maintained at 200nm to 500nm.

[0026] Preferably, step S102 includes the following steps: controlling the mixing of acetic acid and ethanol at a molar ratio of 1:1.1 to 1:1.3 and then introducing them, and controlling the reaction temperature of the esterification reaction in the countercurrent reaction separation space at 85°C to 115°C, and the reaction pressure at atmospheric pressure.

[0027] Preferably, after step S104, the following steps are also included: Step S105: Collect the reaction waste liquid from the bottom of the countercurrent reaction separation space and measure the mass percentage concentration of water in the reaction waste liquid; Step S106: Calculate the circulation regeneration rate of the reaction waste liquid entering the regeneration unit based on the mass percentage concentration and the preset total circulation flow rate of the catalytic-extraction multiphase flow liquid.

[0028] Preferably, step S101 further includes the step of: adjusting the dynamic viscosity of the catalytic-extraction multiphase flow liquid at 100°C to 15 mPa·s to 35 mPa·s, and controlling the surface tension of the catalytic-extraction multiphase flow liquid on the structured packing surface to be not less than 45 mN / m.

[0029] Preferably, when obtaining ethyl acetate in step S104, the mass purity of ethyl acetate at the top of the countercurrent reaction separation space is controlled to be no less than 98.5%, and the single-pass conversion rate of acetic acid is controlled to be no less than 97%.

[0030] Preferably, the regeneration unit includes a stripping tower, and after step S106, the following steps are included: introducing the reaction waste liquid into the stripping tower, destroying the hydration structure of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and water molecules at a stripping temperature of 130°C to 150°C, and returning the resulting regenerated liquid to step S101 after removing the water.

[0031] Preferably, after step S106, the step is: feeding back the latent heat of vapor condensation generated at the top of the stripping tower to step S102 via a heat pump circulation path to preheat the mixture of acetic acid and ethanol.

[0032] Preferably, the local inorganic salt dissolution balance in the countercurrent reaction separation space is adjusted by the side-line water supply pipeline, and the real-time solubility of CaCl2 is determined based on the real-time monitored liquid phase refractive index data, so as to control the real-time concentration of CaCl2 to be maintained below 95% of its saturation concentration curve.

[0033] Example 1: In the continuous industrial production process of ethyl acetate, a bulk organic solvent, the countercurrent reaction separation space is constrained by the thermodynamic equilibrium of the esterification reaction and the formation of a ternary azeotrope with ethyl acetate, ethanol, and water. This results in stagnant conversion and increased energy consumption in the separation process. A catalytic-extraction multiphase flow liquid is sprayed onto the top of the countercurrent reaction separation space. The catalytic-extraction multiphase flow liquid comprises 15 to 25 parts by weight of... An ionic liquid, CaCl2 in a molar ratio of 0.2:1 to 0.5:1 relative to the ionic liquid, and a phase transfer hydrogel matrix composed of a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and deionized water are used. Acetic acid and ethanol are mixed in a molar ratio of 1:1.1 to 1:1.3 and introduced through the center of the countercurrent reaction separation space, allowing the reactants to react in a reaction with a specific surface area of ​​250 m². 2 / m 3 up to 500m 2 / m 3 The structured packing surface contacts the downward multiphase flow liquid. The structured packing metal plate surface is etched with arrayed guide grooves with a depth of 10μm to 50μm. Based on the principle of boundary layer separation in fluid mechanics, the rising main airflow passes through the abrupt change region of the arrayed guide groove cross section to generate high-frequency local eddies. The eddy dissipation generates gas-liquid shear stress, which is transferred to the interior of the multiphase flow liquid through the solid-liquid interface boundary layer of the metal plate. By limiting the boundary with specific physical size, part of the kinetic energy of the main airflow is concentrated on the phase interface to maintain the particle size of the dispersed phase.

[0034] Within the flow field generated on the surface of the structured packing The Brønsted acid sites provided by the ionic liquid initiate an interfacial esterification reaction. Since the reaction temperature is controlled within the range of 85℃ to 115℃, higher than the cloud point of the aqueous solution of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, the triblock copolymer undergoes a thermally induced dehydration phase transition within the flow system and precipitates at the interface between the ionic liquid phase and the calcium chloride aqueous solution phase. Under the condition of high temperature and high salt environment, where the polymer additives tend to undergo salting-out polymerization, the gas velocity in the empty tower within the countercurrent reaction separation space is adjusted to the range of 0.8 m / s to 1.5 m / s. A dynamic dissipation equilibrium is established using the high-frequency gas-liquid shear stress generated by the rising gas phase and the salting-out cohesion of the triblock copolymer. This maintains the particle size of the liquid film dispersed phase on the structured packing surface of the catalytic-extraction multiphase flow liquid at 200 nm to 500 nm, keeping the interfacial shielding layer in a sub-μm dynamic stable state. Under the physical isolation of the interfacial shielding layer, water molecules diffuse through the micropores of the polymer segments into the calcium chloride aqueous solution phase and are converted by Ca... 2+ Hydration capture, while the spatial steric barrier of the interface shielding layer prevents hydrated calcium ion clusters from reverse permeating into the ionic liquid phase, maintaining the stability of the catalytic active center, and obtaining ethyl acetate with a mass purity of not less than 98.5% from the top of the countercurrent reaction separation space, and the single-pass conversion rate of acetic acid exceeds the thermodynamic equilibrium limit and remains stable at over 97%.

[0035] Example 2: On a pilot-scale continuous countercurrent packed reactor with a temperature resolution of 0.1℃ and an empty tower gas velocity adjustment accuracy of 0.01m / s, data on the concentration distribution and phase change of each component generated by physical experiments were collected. Regarding the setting of the empty tower gas velocity, the technical trade-off lies in the inhibitory effect of the gas-liquid interface shear force on polymer salting-out and polymerization on the effective residence time of the reactants within the packing layer. The decision rule is based on the relationship between the liquid film shear stress τ and the gas velocity u. g In terms of the added fluid dynamics logic, when the air velocity u in the empty tower... g When the velocity is in the range of 0.8 m / s to 1.5 m / s, the gas phase kinetic energy counteracts the aggregation tendency of the copolymer caused by the increase of electrolyte concentration, ensuring that the particle size of the liquid film dispersed phase is in the sub-μm scale. In one test condition of this embodiment, the gas velocity was selected as 1.2 m / s, and a high-frequency pressure disturbance with an amplitude of 0.1 m / s was superimposed at the gas flow source.

[0036] Under the condition that the thermodynamic equilibrium baseline conversion rate for ethyl acetate synthesis is set at 68.4%, A comparison of the sample group of the present invention, composed of ionic liquid, calcium chloride aqueous solution, and triblock copolymer, with a control sample group lacking triblock copolymer, revealed that the control sample group exhibited interfacial failure after 30 minutes of continuous operation, leading to Ca... 2+The acetic acid diffuses into the ionic liquid phase and poisons the catalytically active sites, causing the acetic acid conversion rate to decrease from 92.5% to 71.2%. In the same operating conditions, the sample of this invention utilizes the thermally induced dehydration phase transition generated by the triblock copolymer to form a sub-μm shielding layer at the interface, and the measured interfacial water molecule flux is 4.22 × 10⁻⁶. -4 mol / (m 2 The data from ·s) confirmed the sustainability of in-situ dehydration. The key intermediate data recorded that the average particle size of the liquid film dispersed phase maintained on the packing surface was 342 nm, and the deviation of this value was less than 15 nm under ambient temperature fluctuations of ±5℃. The final results showed that the single-pass conversion rate of acetic acid increased from the baseline of 68.4% and stabilized at 97.6%, proving the synergistic mechanism formed by physical isolation and chemical hydration among the components.

[0037] The stress verification results for the numerical range boundaries show that when When the amount of ionic liquid was reduced from 20 parts to 10 parts below the lower limit of the defined range, the conversion rate decreased to 82.4% because the density of Brønsted acid sites was insufficient to support the feed rate, reflecting that the catalytic rate became the limiting factor of the system. When the empty column gas velocity was increased to 1.8 m / s above the upper limit of the defined range, the turbidity of the ethyl acetate product was observed to increase from 0.52 NTU to 12.85 NTU, and the purity of the product obtained from the top of the column dropped from 98.8% to 91.3%. The data trend indicates that the excessively high rising gas phase momentum caused mist entrainment, allowing inorganic salts and copolymers in the multiphase liquid to enter the product stream. This confirms that the gas velocity range of 0.8 m / s to 1.5 m / s is the working window for balancing phase stability and separation efficiency. Finally, the purity of the ethyl acetate product was determined by gas chromatography to be 98.7%, and the single-pass yield of acetic acid was stable at 97.2%.

[0038] Example 3: During the parameter calibration and debugging of the continuous ethyl acetate production system, the interfacial stability of the catalytic-extraction multiphase flow liquid on the structured packing surface is affected by the material ratio and thermal conditions. A microscopic shielding layer is maintained by establishing phase evolution criteria and flow field dynamics compensation procedures. In the initial state definition stage, a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with a weight-average molecular weight of 10,000 and a polyoxyethylene segment to polyoxypropylene segment mass ratio of 35:65 is selected as the reference component. The initial cloud point temperature of the phase transfer hydrogel matrix in deionized water is measured. CaCl2 with different molar ratios is introduced into a constant-temperature stirred reactor to simulate the salting-out environment in the esterification reaction separation space. The thermally induced phase transition temperature T of the triblock copolymer is determined. tr With CaCl2 molar concentration The increase shows a decreasing trend, through the functional relationship. Determine the critical point of phase transition at different salt concentrations; where T trT0 is the thermally induced phase transition temperature, T0 is the initial cloud point temperature in the pure water system, k is the salting-out compensation coefficient, and C is the temperature at which the phase transition temperature is induced. salt The molar concentration of CaCl2 is given. According to this determination model, when the reaction temperature is set at 95℃ and the molar ratio of CaCl2 is 0.3, the precipitation rate of the triblock copolymer at the interface reaches equilibrium with the liquid film shear rate.

[0039] To address the microstructure formed by the phase-transfer hydrogel matrix on the surface of the structured packing material, a bypass optical sampling procedure was introduced to eliminate interference from the gas-phase flow field. A side-sampling branch was drawn from the column section containing the countercurrent reaction separation space to extract a constant-volume fluid sample and introduce it into a quartz cuvette in a darkroom equipped with a circulating, temperature-controlled water jacket. This isolates the background caused by droplet collisions and bubble scattering from the main rising gas flow within the column. To maintain the phase fidelity of the sampled fluid, the side-sampling branch employs an isokinetic sampling probe, and an equivalent shear force field equivalent to that inside the reaction column is generated through a built-in micro-Venturi tube. In the sampling procedure, the Reynolds number Re in the sampling tube is kept within ±5% of the Reynolds number in the packing layer pore channels by adjusting the flow rate of the side-line pump. This ensures that the microscopic condensation state of the triblock copolymer is physically consistent with the in-situ operating conditions within the column at the moment of cuvette detection, eliminating phase rebound errors caused by sampling pressure reduction or flow rate changes. The liquid film pulsation frequency under different shear stresses is monitored using a dynamic light scattering instrument. The transmembrane transport resistance of water molecules is controlled by the degree of thermal condensation of polymer chain segments. When the empty column gas velocity u in the countercurrent reaction separation space is... g When the velocity increases from 0.8 m / s to 1.5 m / s, the shear force generated in the gas phase inhibits the aggregation tendency of polymer molecules, maintaining the interfacial shielding layer in the thickness range of 300 nm to 400 nm. At this point, the effective diffusion coefficient D of water molecules through the polymer solvation layer to the CaCl2 aqueous solution phase is [value missing]. w Maintained at 1.2×10 -9 m 2 / s or more, while Ca 2+ The penetration rate within this shielding layer is less than 5.0 × 10⁻⁶. -13 m 2 / s, at the physical level, constructs a selective transport pathway to block the direct contact between the catalytic active site and hydrated metal ions.

[0040] In the selection and calibration process of the empty tower gas velocity, based on the liquid phase spray density output by the circulating pump in the system and the real-time data fed back by the gas phase flow meter, the surface tension gradient and Weber number We of the liquid film are calculated. The calibration judgment rule is set as follows: when the Weber number We of the liquid film is in the range of 15 to 45, the shear dissipation of the gas-liquid interface inhibits the salting-out and aggregation of the copolymer. If the particle size of the dispersed phase in the liquid film monitored in real time exceeds 500 nm, the empty tower gas velocity is adjusted upward by 0.05 m / s until the particle size falls back to the preset range. In the industrial verification of continuous operation for 120 hours using this method, the pressure drop fluctuation on the surface of the structured packing is less than 2%, and the purity of the obtained ethyl acetate product is stable at 98.8%. The retention rate of Brønsted acid sites in ionic liquids is not less than 99.2%.

[0041] Example 4: In the production preparation stage involving the switching of multiple batches of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer, the properties of the phase transfer hydrogel matrix are affected by the fluctuation of the weight-average molecular weight of the raw materials. This is addressed by implementing a set of measures targeting the cloud point temperature T... cp The pre-calibration procedure was revised to correct the process baseline. Samples were extracted from the new batch of copolymer and prepared into a 5% (w / w) aqueous solution. The transmittance of the solution was monitored with increasing temperature using a spectrometer with a temperature control unit. The temperature at which the transmittance decreased to 50% of the initial value was recorded as the characteristic cloud point temperature of that batch of raw materials. Based on functional relationships Calculate the reaction temperature setpoint T under the current operating conditions. set , among which, T set Set the reaction temperature value. The characteristic cloud point temperature is denoted by α, which is the concentration compensation constant and has a value of 15℃·L / mol; C salt The parameter shift generated by this procedure, where CaCl2 is the molar concentration, causes the thermally induced dehydration phase change to occur at the liquid film interface on the structured packing surface under preset conditions.

[0042] When the system is under conditions of fluctuating feed load or deviation of the tension gradient in the confined space of the liquid film on the structured packing surface, a set of empty tower gas velocity feedback regulation procedures based on surface tension monitoring is implemented to maintain the stability of the dispersed phase particle size in the liquid film. The surface tension gradient value of the liquid film is sampled at the outlet end of the countercurrent reaction separation space and obtained using a tensiometer. When this gradient value is detected to deviate from the equilibrium range, the stability of the dispersed phase particle size is maintained based on the Weber number We and the dispersed phase particle size d. p The image model is used to calculate the gas phase kinetic energy compensation. If the measured upper limit of the radial direction of the liquid film dispersed phase particles (500 nm) is close to the target value, the adjustment unit increases the empty tower gas velocity u with an incremental gradient of 0.02 m / s. g Until the median particle size returns to the central target value of 350 nm, the purity of the ethyl acetate produced at the top of the countercurrent reaction separation space is maintained at over 98.5%.

[0043] Example 5: In the pre-deployment calibration procedure for the compatibility of structured packings of different specifications, the specific surface area of ​​250m² was measured. 2 / m 3 up to 500m 2 / m 3 The diameter d of the pore channels on the surface of the regular packing h With static contact angle θ c A correlation model was established to determine the initial spray intensity of the catalytic-extraction multiphase fluid. In the operational path of this procedure, Multiple calibration solutions were prepared by mixing ionic liquids and phase-transfer hydrogel matrices at mass ratios ranging from 1:2 to 1:5. The surface tension σ of the different solutions within the temperature range of 85℃ to 115℃ was obtained using a dynamic surface tension meter with a temperature control unit. The film spreading rate v was then established. f With the wettability θ of the filler surface w The response matrix is ​​selected to achieve the desired wettability θ on the packing surface. w Maintaining above 95% and a liquid film spreading rate v f The sample solution ratio within the range of 0.1 m / s to 0.3 m / s is used as the production set value.

[0044] When the system enters a stable operating state and the particle size d of the liquid film dispersed phase in the countercurrent reaction separation space is... p When transient drift occurs due to external heat flux interference, the system maintains the stability of the interface shielding layer by executing an adaptive kinetic energy compensation procedure based on the conservation of the Weber number We. This procedure uses sensors to collect feedback signals of the dispersed phase particle size in the liquid film in real time and transmits them to the judgment unit. The judgment unit compares the collected measured values ​​with the preset target value of 350 nm and calculates the particle size deviation Δd. If the absolute value of the particle size deviation Δd is greater than the threshold of 50 nm for 10 consecutive sampling periods, the system determines that a phase aggregation trend has occurred and calculates the empty tower gas velocity u according to the formula Δu=β·Δd. g The compensation step amount is Δu, where Δu is the increase in empty tower gas velocity, β is the response gain coefficient with a value of 0.001 m / (s·nm), and Δd is the particle size deviation. This procedure maintains the purity of ethyl acetate produced at the top of the countercurrent reaction separation space at over 98.5% under continuous load fluctuation conditions.

[0045] Example 6: Under extremely high feed load conditions, i.e., acetic acid feed exceeding the rated value by 20%, the hydrophobic collapse behavior of the polyoxypropylene segment in the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer determines the packing density of the interfacial shielding layer. By adjusting the mass ratio of polyoxyethylene to polyoxypropylene segments in the phase transfer hydrogel matrix to the range of 35:65 to 40:60, a micro-interface with asymmetric osmotic pressure is constructed at a reaction temperature of 105°C. At this time, the hydrophobic polyoxypropylene segment shrinks inward toward the center of the liquid film and forms a continuous hydrophobic framework, blocking the mass transfer path of hydrated calcium ions, while the hydrophilic polyoxyethylene segment extends toward the aqueous phase to form water-capturing channels, thus increasing the interfacial water molecule diffusion coefficient D. w A positive correlation was observed with acetic acid concentration. When the reaction temperature was above the cloud point, the polyoxypropylene segments of the triblock copolymer underwent thermal collapse to form a continuous nonpolar hydrophobic network, constituting a framework to resist ion penetration. Simultaneously, the polyoxyethylene segments adsorbed free water molecules in the system through hydrogen bonding, constructing nanoscale hydration channels within the hydrophobic framework. These channels utilized the strong solvation effect between the oxygen atoms of the polyoxyethylene ether bonds and water molecules, inducing water molecules to migrate directionally through a synergistic jumping mechanism of physical adsorption-desorption. Since the Stokes radius of the hydrated metal ion clusters was much larger than the effective pore size of the percolation channels and subjected to electrostatic repulsion from the hydrophobic framework, absolute isolation of electrolyte ions was achieved while ensuring efficient water removal. Ultimately, it was observed that the mass percentage of water in the top product remained below 0.15% during periods of significant fluctuation in the acetic acid feed, confirming the structure-activity relationship between the segment polarity distribution and interfacial shielding effectiveness of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer.

[0046] In the pre-preparation procedure of the phase transfer hydrogel matrix, a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer with a weight-average molecular weight of 8000 to 12000 is dissolved in deionized water at a low temperature of 5°C to 10°C to prepare a clear solution with a mass concentration of 8% to 12% as a stock solution. To establish a correlation model between the viscosity μ of the catalytic-extraction multiphase flow liquid and the spray film formation performance, a relative viscosity μ is introduced into the stock solution. The CaCl2 component with a molar ratio of ionic liquid of 0.5:1 was measured to have a dynamic viscosity of 15 mPa·s to 25 mPa·s at 25 °C using a rotational viscometer. If the measured viscosity was lower than the target range, 0.5% by mass of triblock copolymer was added and mechanical stirring at 200 rpm was performed until the system reached homogeneity. The flowing liquid prepared in this way was introduced into the countercurrent reaction separation space and, with an empty tower gas velocity of 0.8 m / s to 1.5 m / s, a dynamic liquid film with an average thickness of 350 nm and shear thinning characteristics was spontaneously formed on the surface of the structured packing.

[0047] The embodiments of this application have been described above with reference to the accompanying drawings. Unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other. This application is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of this application without departing from the spirit of this application and the scope of protection of this invention, and all of these forms are within the protection scope of this application.

Claims

1. A phase-transfer-controlled catalytic synthesis process for ethyl acetate, characterized in that, Includes the following steps: Step S101: Spray a catalytic-extraction multiphase flow liquid onto the top of the countercurrent reaction separation space. The catalytic-extraction multiphase flow liquid contains, by weight, 15 to 25 parts of... Ionic liquid, CaCl2 in a molar ratio of 0.2:1 to 0.5:1 relative to the ionic liquid, and a phase transfer hydrogel matrix composed of a polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and deionized water; Step S102: The mixture of acetic acid and ethanol is introduced into the middle of the countercurrent reaction separation space, so that the mixture of acetic acid and ethanol comes into contact with the catalytic-extraction multiphase flow liquid on the surface of the structured packing. Step S103: Control the gas velocity in the empty tower within the countercurrent reaction separation space to be in the range of 0.8 m / s to 1.5 m / s. Use the shear force field generated by the gas phase to maintain the particle size of the liquid film dispersed phase on the surface of the structured packing at 200 nm to 500 nm, thereby inhibiting the polymerization of polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer. In step S104, the water generated by the esterification reaction is transferred to the phase transfer hydrogel matrix by the solvation effect of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer on water molecules, and ethyl acetate is obtained from the top of the countercurrent reaction separation space.

2. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, Step S101 includes the following steps: selecting a copolymer with a weight average molecular weight of 8,000 to 12,000 and a mass ratio of ethylene oxide segment to propylene oxide segment of 3:7 to 4:6 as a ethylene oxide-propylene oxide-ethylene oxide triblock copolymer, and controlling the mass percentage concentration of the ethylene oxide-propylene oxide-ethylene oxide triblock copolymer in the phase transfer hydrogel matrix to be 2% to 5%.

3. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, Step S103 includes the following steps: using the shear force field generated in the gas phase to make the catalytic-extraction multiphase fluid flow in a specific surface area of ​​250 m² 2 / m 3 up to 500m 2 / m 3 A liquid film is formed on the surface of the regular filler, and the thickness of the interface shielding layer is maintained at 200nm to 500nm.

4. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, Step S102 includes the following steps: controlling the mixing of acetic acid and ethanol at a molar ratio of 1:1.1 to 1:1.3 and introducing them into the mixture, and controlling the reaction temperature of the esterification reaction in the countercurrent reaction separation space to be between 85°C and 115°C, and the reaction pressure to be atmospheric pressure.

5. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, The steps following step S104 are as follows: Step S105: Collect the reaction waste liquid from the bottom of the countercurrent reaction separation space and measure the mass percentage concentration of water in the reaction waste liquid; Step S106: Calculate the circulation regeneration rate of the reaction waste liquid entering the regeneration unit based on the mass percentage concentration and the preset total circulation flow rate of the catalytic-extraction multiphase flow liquid.

6. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, Step S101 further includes the step of: adjusting the dynamic viscosity of the catalytic-extraction multiphase flow liquid at 100°C to 15 mPa·s to 35 mPa·s, and controlling the surface tension of the catalytic-extraction multiphase flow liquid on the structured packing surface to be not less than 45 mN / m.

7. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, When obtaining ethyl acetate in step S104, the purity of ethyl acetate at the top of the countercurrent reaction separation space is controlled to be no less than 98.5%, and the single-pass conversion rate of acetic acid is controlled to be no less than 97%.

8. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 5, characterized in that, The regeneration unit includes a stripping tower. After step S106, the following steps are included: introducing the reaction waste liquid into the stripping tower, destroying the hydration structure of the polyoxyethylene-polyoxypropylene-polyoxyethylene triblock copolymer and water molecules at a stripping temperature of 130°C to 150°C, and returning the resulting regenerated liquid to step S101 after removing the water.

9. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 8, characterized in that, Step S106 is followed by the step of feeding back the latent heat of vapor condensation generated at the top of the stripping tower to step S102 via a heat pump circulation path to preheat the mixture of acetic acid and ethanol.

10. The ethyl acetate catalytic synthesis process based on phase transfer regulation according to claim 1, characterized in that, The local inorganic salt dissolution balance in the countercurrent reaction separation space is adjusted by the side-line water supply pipeline. The real-time solubility of CaCl2 is determined based on the real-time monitored liquid phase refractive index data, and the real-time concentration of CaCl2 is controlled to be maintained below 95% of its saturation concentration curve.

Images