Reflux device and method for producing aluminum sec-butoxide

Abstract

The invention discloses a reflux device and method for producing aluminum sec-butoxide, relates to the technical field of preparation of organic aluminum compounds, and aims to solve the problems that near-boiling residues are difficult to separate, the reflux efficiency is low and the improvement cost is high in the existing aluminum sec-butoxide production. The device comprises a reaction unit, an adsorption-condensation integrated separation unit, a directional reflux distribution unit and a hydrogen recovery unit, and all the units are matched with existing reaction kettles. The method comprises the steps of pretreatment, reaction reflux and post-treatment. The purity of aluminum sec-butoxide is larger than or equal to 97.5%, the conversion rate of aluminum powder is larger than or equal to 90%, the cost per ton is reduced by 1500 yuan, the transformation cost is 0.28 million yuan, and the method is suitable for low-cost transformation of small and medium-sized enterprises.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically proposes a reflux apparatus and method for producing aluminum sec-butoxide. Background Technology

[0002] Aluminum sec-butoxide, a key intermediate in organic synthesis, relies on the solid-liquid reaction between aluminum powder and sec-butanol under heating conditions for its industrial production. The reaction equation is: 2Al + 6(CH3CH2CH(OH)CH3) → 2Al(OCH(CH3)CH2CH3)3 + 3H2↑. This reaction requires a reflux system to achieve raw material recycling and reaction environment control. However, existing reflux systems in industrial production face three major technical bottlenecks that urgently need to be addressed, severely restricting product quality and production economics: The raw material sec-butanol (boiling point 99.5℃) inevitably contains isobutanol (boiling point 99.5℃) and water (boiling point 100℃), with a boiling point difference of only 0.5-1℃. Traditional reflux systems rely solely on conventional condensation devices, which cannot disrupt the near-boiling liquid's vapor-liquid equilibrium, resulting in a high content of impurities (isobutanol + water) in the reflux liquid. Excessive impurities can trigger serious side reactions: on the one hand, water reacts with aluminum powder to form aluminum hydroxide, which not only consumes the raw material aluminum powder but also forms solid residues that affect product purity; on the other hand, isobutanol undergoes an ester exchange reaction with aluminum sec-butoxide to generate impurity aluminum alkoxides, ultimately resulting in the finished aluminum sec-butoxide having a purity of only 92-95%, which cannot meet the purity requirements of high-end organic synthesis.

[0003] Traditional reflux systems use a "single-pipe direct-fall" reflux method, where the reflux liquid only performs the single function of "raw material recovery," which cannot adapt to the complex reaction environment inside the reactor and causes multiple problems: Local overheating carbonization: Due to its high density, aluminum powder at the bottom of the vessel tends to accumulate, and the reflux liquid cannot directly cover this area. As a result, the temperature at the bottom of the vessel often exceeds 105°C during jacket heating. The sec-butanol undergoes a carbonization reaction, and the resulting carbon slag adheres to the surface of the aluminum powder, further inhibiting the reactivity of the aluminum powder. Raw material volatilization loss: The reflux liquid only drips from the top of the vessel and cannot form an effective liquid film on the liquid surface. About 10-15% of the vapor generated by boiling of sec-butanol evaporates directly into the atmosphere, increasing the raw material consumption. Uneven mixing and low conversion rate: Single-pipe reflux cannot enhance the mixing of materials in the reactor, and the aluminum powder and sec-butanol do not come into sufficient contact, resulting in a single-pass conversion rate of aluminum powder that is generally less than 75%. Multiple additions of raw materials are required to increase output, which further increases production costs.

[0004] To address the aforementioned issues, existing technologies have significant shortcomings in terms of improvement: some technologies (such as patent CN218458688U) only improve condensation efficiency by optimizing the condenser structure and adding baffles, but do not address the core challenge of near-boiling matter separation; a few companies have attempted to separate near-boiling matter using distillation, which can increase the purity of sec-butanol to over 99.5%, but requires additional equipment such as distillation columns and reboilers, with a single set investment exceeding 500,000 yuan. Furthermore, the energy consumption of the distillation process increases by 30% compared to traditional processes, far exceeding the cost affordability of small and medium-sized chemical enterprises. Therefore, the industry urgently needs a technical solution that balances "efficient separation of near-boiling matter, optimized reflux function, and low-cost retrofitting" to meet the upgrade needs of existing production lines in small and medium-sized enterprises. Summary of the Invention

[0005] In view of this, the present invention proposes a reflux apparatus and method for producing aluminum sec-butoxide.

[0006] The technical solution of this invention is achieved as follows: This invention achieves efficient separation of near-boiling substances, precise control of the reaction environment, and low-cost modification through the synergistic design of "adsorption-condensation coupling separation" and "directional reflux distribution". The specific technical solution is as follows: This device is based on the existing 500-2000L reactor design and adopts a modular assembly method. It can be directly connected to existing equipment via flanges or quick-connect couplings without replacing the reactor body. The device as a whole includes a reaction unit, an integrated adsorption-condensation separation unit, a directional reflux distribution unit, and a hydrogen recovery unit. These units work together to achieve a closed-loop process of "reaction-separation-reflux-by-product utilization". The reaction unit is the core carrier for material reaction, adapted to the modification of existing reaction vessels, and its specific structure includes: Reactor: Made of 316L stainless steel (resistant to corrosion by sec-butanol and aluminum alkoxides), with a volume ranging from 500 to 2000L; the outer wall of the reactor is equipped with a jacket, and heat transfer oil at 50-120℃ is circulated inside the jacket. The temperature is precisely controlled within ±1℃ through a temperature control system to avoid side reactions caused by local temperature fluctuations. Stirring components: An anchor-type stirring paddle (paddle diameter is 0.6-0.8 times the vessel diameter) is used, which is suitable for aluminum powder accumulation at the bottom of the vessel and can effectively stir the bottom material; the stirring paddle is equipped with a variable frequency motor with an adjustable speed range of 50-300 r / min, which can dynamically adjust the stirring intensity according to the reaction stage; Temperature monitoring components: At least two PT100 platinum resistance thermometers are installed along the height of the reactor (at 1 / 4, 1 / 2, and 3 / 4 of the reactor height), with a measurement range of 0-200℃ and an accuracy of ±0.5℃, to monitor the temperature of different areas inside the reactor in real time and provide data support for reflux distribution adjustment.

[0007] The integrated adsorption-condensation separation unit is connected in series at the gas phase outlet at the top of the reactor (via a DN50 flange), with a total length of 1.2-1.5m and an inner diameter of 100-150mm (matched to the reactor volume). A primary adsorption section, a condensation section, and a secondary adsorption section are sequentially arranged along the direction of mixed steam flow to achieve stepwise removal of near-boiling substances. Primary adsorption stage: filled with 3A molecular sieve (particle size 3-5mm, bulk density 0.65g / cm³). 3 The filling height is 300-400mm; the 3A molecular sieve only adsorbs water molecules (the pore size matches the diameter of water molecules and does not adsorb sec-butanol and isobutanol), which can reduce the moisture content in the mixed steam to the corresponding humidity <5%RH; a wire mesh demister is installed at the top of the adsorption section to prevent aluminum powder dust in the reactor from entering the adsorption layer with the steam and avoid clogging of the molecular sieve. Condensation section: adopts a shell-and-tube structure with a heat exchange area of ​​2-5 m². 2 (Matching based on reactor volume), tube diameter 19mm, tube length 500mm; 20-30℃ circulating water (flow rate 10-20m³ / h) is introduced into the shell side. 3 ( / h), which can condense the mixed vapor (sec-butanol + isobutanol) after primary adsorption into liquid, with a condensation efficiency ≥98%; Secondary adsorption section: filled with hydrophobically modified activated carbon (columnar, 4mm in diameter, 8mm in length, with an isobutanol adsorption capacity ≥0.3g / g), with a filling height of 200-300mm; the hydrophobically modified activated carbon preferentially adsorbs isobutanol (its hydrophobic properties inhibit the adsorption of sec-butanol), which can increase the purity of sec-butanol in the condensate to ≥99.5%; Monitoring components: A humidity sensor (measurement range 0-100%RH, accuracy ±2%) is installed at the outlet of the primary adsorption section to monitor the dehydration effect in real time; an online refractometer (accuracy ±0.1%) is installed at the outlet of the secondary adsorption section to detect the concentration of sec-butanol in real time to ensure that the purity of the reflux liquid meets the standard.

[0008] The directional reflux distribution unit is connected to the outlet of the integrated adsorption-condensation separation unit and serves as a precise distribution carrier for the reflux liquid. All components are made of 316L stainless steel, and the specific structure includes: Main pipeline and flow monitoring: The main pipeline diameter is 50mm, equipped with an electromagnetic flow meter (measuring range 0.1-5m). 3 / h, accuracy ±1%), real-time monitoring of total return flow; Branch pipe and nozzle design: Includes 3 branch pipes corresponding to the "bottom area, stirring area, and liquid surface area" of the reactor, respectively. Each branch pipe is equipped with a matching nozzle at the end to achieve differentiated reflux liquid function: Bottom branch pipe: 25mm in diameter, arranged in a circular array along the bottom of the reactor, with the end nozzle facing the center area of ​​the bottom of the reactor. The installation position is 50-80mm away from the bottom of the reactor. It can form a vortex or turbulent flow through circumferential spraying, directly dispersing the aluminum powder accumulation at the bottom of the reactor, while cooling the local high temperature area. Branch pipe in the reactor: 32mm in diameter, with an angled nozzle at the end. The nozzle faces the area where the stirring component is located and is 100-150mm horizontally away from the stirring paddle. It can enhance the mixing of materials by means of the stirring flow field and improve the contact efficiency between aluminum powder and sec-butanol. Top branch pipe: 20mm in diameter, with an umbrella-shaped nozzle at the end, installed 100-150mm from the liquid surface, which can form a uniform liquid film on the liquid surface and suppress the volatilization of sec-butanol vapor; Control components: Each branch pipe is equipped with an electric regulating valve (adjustment range 0-100%, response time <2s). All electric regulating valves are linked with the PLC controller, which can dynamically adjust the return flow ratio of each branch pipe according to the real-time data of the temperature monitoring device and the online refractometer.

[0009] The hydrogen recovery unit is used to recover hydrogen (a byproduct) generated in the reaction, taking into account both safety and energy saving. Specifically, it includes: Branch pipeline: Leads out from the gas phase outlet at the top of the reactor (diameter 25mm), equipped with a check valve (opening pressure 0.02MPa) to prevent hydrogen backflow; Dryer: Filled with 4A molecular sieve (for dehydration), with a throughput of 0.5-2 m³. 3 / h, removes trace amounts of moisture from hydrogen to prevent moisture from affecting subsequent combustion and utilization; Hydrogen storage tank: 0.5-1m³ 3 The working pressure is 0.1 MPa. The outlet is connected to the fuel pipeline of the reactor jacket. The recovered hydrogen can replace 15-25% of the natural gas, reducing fuel costs and eliminating the safety hazards of direct hydrogen emission.

[0010] This invention also provides a reflux method for producing aluminum sec-butoxide. This method is implemented based on the aforementioned apparatus, and its core involves a "pretreatment-reaction and reflux-posttreatment" process to achieve efficient production of aluminum sec-butoxide. The specific steps are as follows: Preprocessing: Pretreatment aims to improve the reactivity of raw materials and reduce the introduction of initial impurities: Aluminum powder pretreatment: Select industrial aluminum powder with a purity of ≥99.5%, crush it to 80-120 mesh (particle size 150-180μm, to increase specific surface area), and mix it with 0.6-1.0wt% iodine (catalyst, to accelerate the reaction between aluminum powder and sec-butanol) for later use; Pretreatment of sec-butanol: Select industrial-grade sec-butanol with a purity of ≥99%, preheat it to 55-65℃ through a waste heat exchanger (to reduce the energy consumption of heating the reactor and shorten the reaction start-up time), and set it aside.

[0011] Reaction and reflux steps: This step is the core of the production process, achieving highly efficient reaction through the synergy of "adsorption-condensation separation" and "directional reflux distribution": Feeding and Heating Start-up: Add the aluminum powder-catalyst mixture into the reactor (45-55 kg / 1000 L reactor volume), then add preheated sec-butanol (330-370 kg / 1000 L reactor volume, sec-butanol to aluminum powder molar ratio 3.3:1, ensuring excess sec-butanol); close the feed port, start stirring (initial speed 120-180 r / min), and heat to 95±2℃ by introducing heat transfer oil through the jacket, holding for 30 min to fully wet the aluminum powder and avoid violent local reactions; Adsorption-condensation separation start-up: Continue heating to 95-100℃ to boil sec-butanol and generate mixed steam (sec-butanol + isobutanol + residual moisture); the mixed steam enters the integrated adsorption-condensation separation unit: Primary adsorption stage: 3A molecular sieve adsorbs moisture in the steam until the humidity sensor shows that the outlet humidity is <5%RH; Condensation section: 20-30℃ circulating water condenses the dehydrated steam into liquid; Secondary adsorption stage: Hydrophobically modified activated carbon adsorbs isobutanol in the condensate until the online refractometer shows a sec-butanol concentration ≥99.5%, resulting in a high-purity reflux liquid; Directional reflux distribution: The high-purity reflux liquid is sprayed through the three branch pipes of the directional reflux distribution unit. The initial distribution ratio is: 30-40% in the bottom area of ​​the vessel (dispersing aluminum powder + temperature control), 40-60% in the middle area of ​​the vessel (enhancing mixing), and 10-30% in the top area of ​​the vessel (inhibiting volatilization). Dynamic adjustment: After the reaction has proceeded for 4-5 hours, adjust the parameters based on the data from the temperature monitoring device. If the temperature at the bottom of the vessel is >103℃, increase the proportion of reflux liquid in the bottom branch pipe to 35-45%, and at the same time increase the stirring speed to 180-220 r / min to enhance the cooling and dispersion effect; If the online refractometer shows that the concentration of sec-butanol is <99.5%, turn off the reflux system and replace the hydrophobically modified activated carbon in the secondary adsorption section (the replacement process takes about 10 minutes and does not require stopping the reaction).

[0012] Post-processing: Post-processing aims to achieve product recovery and adsorbent material regeneration, thereby reducing costs. Product discharge: Continue the reaction until the purity of sec-butoxide aluminum is ≥97.5% (usually 6-8h), then reduce the jacket temperature to 40℃ (to avoid product deterioration at high temperature), and discharge the crude sec-butoxide aluminum through the discharge valve at the bottom of the reactor (because the reflux liquid has high purity, the crude product does not need further purification to meet the standard). Adsorbent material regeneration: 3A molecular sieve: The adsorbed moisture is desorbed by purging with hot air at 140-160℃ for 1.5-2.5 hours, and it can be reused 5-8 times after regeneration; Hydrophobically modified activated carbon: Desorbed by saturated steam at 110-130℃ for 30 minutes, the desorbed isobutanol is recovered (can be used as fuel), and can be reused 3-5 times after regeneration; Hydrogen utilization: The hydrogen recovered from the hydrogen storage tank (purity ≥99%) is connected to the fuel pipeline of the reactor jacket to replace 15-25% of the natural gas and reduce heating energy consumption.

[0013] The present invention has the following advantages over the prior art: For the first time, a tandem adsorption design of 3A molecular sieve combined with hydrophobically modified activated carbon was used in the production of aluminum sec-butoxide, achieving efficient separation of near-boiling substances (water and isobutanol) at room temperature. The purity of the reflux liquid was increased to ≥99.5%, completely solving the problems of traditional condensation being unable to separate near-boiling substances and the high cost of distillation. Compared with existing technologies, the purity of the finished aluminum sec-butoxide was increased from 92-95% to over 97.5%, meeting the needs of high-end application scenarios. The traditional "single-pipe recycling" reflux function has been upgraded to a triple function of "bottom dispersion temperature control, in-vessel enhanced mixing, and top suppression of volatilization". Through the circumferential array nozzles and differentiated spray design, the problems of local overheating at the bottom of the vessel, liquid surface volatilization and uneven mixing are solved, and the single-pass conversion rate of aluminum powder is increased from <75% to over 90%. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a schematic diagram of the connection structure of the reflux device of the present invention; Figure 2 This is a top view of the reactor section in the reflux device of the present invention.

[0016] In the diagram: 1-Reaction vessel, 2-Stirring assembly, 3-Temperature monitoring device, 4-Integrated adsorption-condensation separation unit, 41-First-stage adsorption section, 42-Condensation section, 43-Second-stage adsorption section, 5-Directional reflux distribution unit, 51-Main pipeline, 52-Branch pipe, 521-Bottom branch pipe, 522-Middle branch pipe, 523-Top branch pipe, 6-Wire mesh demister, 7-Humidity sensor, 8-Online refractometer, 9-Electromagnetic flowmeter, 10-Electronic regulating valve Detailed Implementation The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0017] The reflux apparatus for producing aluminum sec-butoxide of the present invention comprises: The reaction unit includes a jacketed reactor 1, a stirring assembly 2, and at least two temperature monitoring devices 3 distributed along the height of the reactor. An integrated adsorption-condensation separation unit 4 is connected in series at the top gas phase outlet of the reactor 1, and is provided with a primary adsorption section 41, a condensation section 42 and a secondary adsorption section 43 in sequence along the direction of mixed steam flow. The primary adsorption section 41 is filled with 3A molecular sieve, and the secondary adsorption section 43 is filled with hydrophobic modified activated carbon. The directional reflux distribution unit 5 is connected to the outlet of the adsorption-condensation integrated separation unit 4. It includes a main pipe 51 and three branch pipes 52. The three branch pipes 52 correspond to the bottom area of ​​the reactor, the stirring area in the reactor, and the liquid surface area at the top of the reactor, respectively. Each branch pipe is equipped with a nozzle adapted to the corresponding area at its end.

[0018] In the integrated adsorption-condensation separation unit 4, a wire mesh demister 6 is provided at the top of the primary adsorption section 41; the condensation section has a tubular structure, and circulating water at 20-30℃ is introduced into the shell side of the condensation section; a humidity sensor 7 is provided at the outlet of the primary adsorption section, and an online refractometer 8 is provided at the outlet of the secondary adsorption section 43.

[0019] In the directional reflux distribution unit 5, an electromagnetic flowmeter 9 is installed on the main pipe 51; the three branch pipes 52 are respectively the bottom branch pipe 521, the middle branch pipe 522, and the top branch pipe 523. The bottom branch pipe 521 is arranged in a circular array along the bottom of the reactor, with its end nozzle facing the center area of ​​the bottom of the reactor, and the nozzle installation position is 50-80mm away from the bottom of the reactor; the end of the middle branch pipe 522 is an oblique nozzle, which faces the area where the stirring component 2 is located, and the horizontal distance between the nozzle and the stirring component 2 is 100-150mm; the end of the top branch pipe 523 is an umbrella-shaped nozzle, which faces the liquid surface inside the reactor, and the installation position is 100-150mm away from the liquid surface; each branch pipe 52 is equipped with an electric regulating valve 10.

[0020] In the reaction unit, the reactor 1 is made of 316L stainless steel, and the jacket is filled with heat transfer oil at 50-120℃, with a temperature control accuracy of ±1℃; the stirring assembly 2 is an anchor-type stirring paddle, the diameter of which is 0.6-0.8 times the diameter of the reactor, and the stirring assembly 2 is equipped with a variable frequency motor with a speed of 50-300r / min; the temperature monitoring device 3 is a PT100 platinum resistance thermometer, the measurement range of which is 0-200℃, with an accuracy of ±0.5℃.

[0021] In the following examples, the 3A molecular sieve was purchased from Zhongying Packing Material, 3-5mm columnar, with a water adsorption capacity of 22%; the hydrophobic activated carbon was purchased from Anhui Juteng New Material, 4*8mm columnar, modified with KH-570.

[0022] Example 1 Precision Separation-Directional Reflux Aluminum sec-Butoxide Production Unit and Application in 1000L Reactor Device structure and connection relationship (a) Reaction Unit 1. Composition and connection of core components Reactor body: made of 316L stainless steel, with an inner diameter of 1200mm and a volume of 1000L; the top of the reactor body has a DN50 gas phase outlet (for connecting the adsorption-condensation unit) and a DN200 feeding port (with a quick-opening sealing cover), and the bottom is welded with a DN100 discharge valve (with a heat insulation jacket). Jacket system: The jacket is set around the outer wall of the reactor body, and the height of the jacket is the same as that of the reactor body (1800mm). The jacket inlet and outlet are connected to the heat transfer oil circulation system through DN40 pipes. The jacket is equipped with a PID temperature controller (model TC-7200), and the temperature controller is connected to the temperature sensor inside the jacket through a signal line. Stirring assembly: The stirring motor (power 5.5kW, frequency converter model VFD-5.5) is connected to the anchor-type stirring paddle through a coupling. The stirring paddle is made of 316L stainless steel, with a diameter of 840mm (0.7 times the inner diameter of the reactor), and a distance of 50mm between the paddle blade and the bottom of the reactor. Temperature monitoring components: Three PT100 platinum resistance thermometers (accuracy ±0.5℃) are vertically inserted through the mounting holes on the top of the reactor to a depth of 50mm. The installation positions are distributed along the height of the reactor at 1 / 4 (450mm), 1 / 2 (900mm), and 3 / 4 (1350mm). The thermometers are connected to the PLC controller (model S7-200) via signal lines.

[0023] 2. Work Process The heat transfer oil circulation system introduces 95-100℃ heat transfer oil into the jacket through the jacket inlet and outlet. The PID temperature controller adjusts the flow rate of the heat transfer oil based on the feedback data from the temperature sensor in the jacket, so that the temperature inside the reactor is controlled within the accuracy range of ±1℃. After the stirring motor is started, it drives the anchor-type stirring paddle to rotate at a speed of 150-200r / min through the coupling, stirring the aluminum powder-sec-butanol mixture in the reactor. Three PT100 thermometers collect temperature data of different areas inside the reactor in real time and transmit it to the PLC controller through the signal line to provide a basis for subsequent reflux adjustment.

[0024] 3. Technical Effects The 316L stainless steel material ensures the reactor is resistant to corrosion from sec-butanol and aluminum alkoxides. The combination of the jacket and PID temperature controller ensures uniform temperature inside the reactor (temperature difference between areas ≤2℃), avoiding local overheating. The anchor-type stirring paddle's size design and speed adjustment are adapted to the aluminum powder accumulation characteristics, effectively breaking up aluminum powder agglomerates (100-mesh aluminum powder accumulation thickness 50-80mm), preventing aluminum powder from settling to the bottom and not reacting. Multi-point temperature monitoring enables real-time monitoring of the temperature field inside the reactor, laying the foundation for precise temperature control.

[0025] (ii) Integrated adsorption-condensation separation unit 1. Composition and connection of core components Unit body: The whole is a 316L stainless steel pipe with a total length of 1400mm and an inner diameter of 120mm. One end of the unit body is sealed to the gas phase outlet at the top of the reactor through a DN50 flange, and the other end is connected to the main pipeline of the directional reflux distribution unit through a flange. Primary adsorption section: Located at the end of the unit body closest to the reactor, the section is 350mm long and filled with 3A molecular sieve (particle size 3-5mm, bulk density 0.65g / cm³). 3 The molecular sieve is fixed at both ends by 316L stainless steel perforated plates (2mm aperture) with a filling capacity of 20kg. A 100-mesh stainless steel wire mesh demister (120mm diameter, 5mm thickness) is welded to the top of the primary adsorption section (near the gas phase inlet). Condensation Section: Located on the side of the primary adsorption section furthest from the reactor, this section is 500mm long and employs a shell-and-tube structure. The tubes are made of 316L stainless steel, with dimensions of Φ19mm × 500mm (2mm wall thickness), totaling 12 tubes. Both ends of the tubes are welded to the unit body via tube sheets, forming a tube side (connected to the main channel of the unit body, carrying mixed steam / condensate) and a shell side (jacket space, carrying circulating water). The shell side inlet and outlet are connected to a 25±2℃ circulating water system via DN32 pipes, with the circulating water flow rate controlled at 15m³ / h using a flow meter. 3 / h; Secondary adsorption section: Located on the side of the condensation section away from the primary adsorption section, the section is 250mm long and filled with hydrophobic modified activated carbon (columnar, Φ4mm×8mm, isobutanol adsorption capacity ≥0.3g / g, filling amount 10kg). The activated carbon is fixed at both ends by 316L stainless steel perforated plates (pore diameter 2mm). Monitoring components: A humidity sensor (model SHT30, measurement range 0-100%RH, accuracy ±2%) is installed on the outlet pipe of the first-stage adsorption section via a threaded interface, and an online refractometer (model DR6000, accuracy ±0.1%) is installed on the outlet pipe of the second-stage adsorption section via a flange interface. Both are connected to the PLC controller via signal lines.

[0026] 2. Work Process The mixed steam (sec-butanol + isobutanol + water) generated in the reactor enters the adsorption-condensation unit through the gas phase outlet. First, it passes through the wire mesh demister at the top of the primary adsorption section to intercept aluminum powder dust entrained in the steam (to avoid contaminating the molecular sieve). Then, the steam passes through the 3A molecular sieve layer, where water molecules are selectively adsorbed by the molecular sieve (the humidity sensor monitors the outlet humidity in real time, and dehydration is considered complete when it drops to <5%RH). The dehydrated steam enters the tube side of the condensation section, where 25°C circulating water in the shell side exchanges heat with the steam through the tube wall, and the steam condenses into a liquid. The condensate continues to flow into the secondary adsorption section, where isobutanol is adsorbed by hydrophobically modified activated carbon (the online refractometer monitors the sec-butanol concentration in the condensate in real time, and purification is considered complete when it rises to ≥99.8%). The purified sec-butanol reflux liquid enters the directional reflux distribution unit.

[0027] 3. Technical Effects The wire mesh demister effectively prevents aluminum powder dust from clogging the pores of the adsorbent material, extending its service life. The tandem adsorption design of 3A molecular sieve and hydrophobically modified activated carbon enables stepwise removal of near-boiling substances (water, isobutanol) at room temperature, avoiding the high energy consumption of distillation methods. The reflux liquid purity consistently reaches over 99.8%, reducing side reactions at the source (aluminum hydroxide formation is reduced by over 90%). The heat exchange area of ​​the tubular condenser section is 3.5m². 2 The steam processing capacity of the 1000L reactor (150kg / h) is matched with the circulating water parameters, and the condensation efficiency is ≥98%, avoiding steam escape and loss.

[0028] (III) Directional Return Distribution Unit 1. Composition and connection of core components Main pipeline: made of 316L stainless steel, Φ50mm×3mm, 500mm in length. One end of the main pipeline is sealed to the outlet of the adsorption-condensation unit via a flange, and the other end is welded to three branch pipes via a tee fitting. Electromagnetic flow meters (model LDG-50, measuring range 0.1-5m) are installed in series on the main pipeline. 3 / h, accuracy ±1%), the flow meter is connected to the PLC controller via a signal line; Bottom branch pipe: Material: 316L stainless steel, specifications: Φ25mm×2mm, length: 800mm, a total of 3 branches, distributed in a 120° circumferential array along the inner wall of the bottom of the reactor. One end of each branch pipe is welded to the tee joint of the main pipe, and the other end extends into the interior of the reactor. The end is connected to a direct-injection nozzle (nozzle diameter: 8mm, spray angle: 15°) by a thread. The center of the nozzle is 60mm away from the bottom of the reactor. Branch pipe in the reactor: material is 316L stainless steel, specification is Φ32mm×2mm, length is 600mm, 1 line, one end is welded to the tee joint of the main pipe, the other end extends to the side of the stirring paddle inside the reactor, and the end is connected to the oblique nozzle (nozzle diameter 10mm, spray angle 45°) by thread. The center of the nozzle is 120mm away from the horizontal distance of the stirring paddle and makes an angle of 45° with the axis of the reactor. Top branch pipe: Material: 316L stainless steel, specifications: Φ20mm×2mm, length: 400mm, 1-way, one end is welded to the tee joint of the main pipe, and the other end extends to the liquid level inside the reactor. The end is connected to an umbrella-shaped nozzle (6mm nozzle diameter, 120° spray angle) by thread. The center of the nozzle is 120mm away from the liquid level inside the reactor (the liquid level is monitored in real time by a level gauge on the outside of the reactor). Control components: Each branch pipe is equipped with an electric regulating valve (model ZAZP-25, adjustment range 0-100%, response time <2s) in series. The regulating valve is connected to the PLC controller through a signal line to realize automatic flow regulation.

[0029] 2. Work Process The high-purity sec-butanol reflux liquid output from the adsorption-condensation unit enters the main pipeline, and the electromagnetic flowmeter collects the total reflux flow rate (approximately 1.2 m³ / s) in real time. 3 / h) and transmit to the PLC controller; the PLC controller, based on the temperature monitoring data of the reaction unit and the preset program, sends instructions to the electric regulating valves of the 3-way branch pipe to control the initial reflux liquid distribution ratio: bottom branch pipe 35% (0.42m 3 / h), 50% of the branch pipe in the reactor (0.6m) 3 / h), 15% of the top branch pipe (0.18m) 3 / h); Bottom branch pipe: The reflux liquid is sprayed into the central area of ​​the bottom of the vessel through a direct-jet nozzle, forming a vortex flow to disperse the accumulated aluminum powder and simultaneously remove heat from the bottom of the vessel. When the temperature monitoring shows that the bottom temperature is >103℃, the PLC controls the bottom branch pipe regulating valve to increase the opening to 40% (flow rate 0.48m³ / h). 3 / h), and simultaneously increase the stirring speed to 200r / min; Branch pipe in the reactor: The reflux liquid is sprayed into the stirring paddle area through the angled nozzle, and superimposed with the shear flow generated by the stirring paddle to enhance the mixing and contact of sec-butanol and aluminum powder. Top branch pipe: The reflux liquid is sprayed onto the liquid surface through an umbrella-shaped nozzle, forming an annular liquid film that covers the entire liquid surface and inhibits the volatilization of sec-butanol vapor.

[0030] 3. Technical Effects The circumferential array of three branch pipes and the differentiated nozzle design achieve a triple function of "bottom temperature control + mixing in the reactor + anti-volatilization at the top of the reactor" for the reflux liquid, breaking through the limitations of traditional single-pipe reflux. The linkage control between the electric regulating valve and the PLC can dynamically adjust the flow rate according to the reaction conditions, avoiding local overheating caused by the lag of manual adjustment (bottom temperature is stably controlled at ≤103℃). The volatilization loss of sec-butanol is reduced from 14.5% in the traditional process to 4.2%, and the single-pass conversion rate of aluminum powder is increased from 72.8% to 90.5%.

[0031] II. Application Methods and Overall Technical Effects 1. Application Steps (1) Pretreatment: 99.5% industrial aluminum powder was crushed to 100 mesh and mixed with 0.8wt% iodine to obtain an aluminum powder-catalyst mixture; 99% industrial grade sec-butanol was preheated to 60±5℃ through a waste heat exchanger; (2) Feeding and heating: Add 50kg of aluminum powder-catalyst mixture and 350kg of preheated sec-butanol to the reactor, and close the feeding port; turn on the stirrer (initial speed 150r / min), and pass 95℃ heat transfer oil through the jacket. Keep it warm for 30min to allow the aluminum powder to be fully wetted. (3) Separation-reflux: Heat to 98-100℃, start the adsorption-condensation unit and the directional reflux unit, and realize the near-boiling substance separation and directional reflux according to the above process. After reacting for 4.5h, dynamically adjust the reflux ratio according to the temperature data. (4) Post-processing: After 7 hours of reaction, samples were taken and tested to find that the purity of aluminum sec-butoxide reached 97.8%. The temperature was lowered to 40°C and the material was discharged. The 3A molecular sieve was regenerated by purging with hot air at 150°C for 2 hours, and the activated carbon was regenerated by desorption with saturated steam at 120°C for 30 minutes. Hydrogen was recovered from the hydrogen storage tank for use as jacket fuel.

[0032] 2. Overall technical effect Product quality: The purity of aluminum sec-butoxide reaches 97.8%, which is 4.6 percentage points higher than that of traditional processes, meeting the needs of high-end organic synthesis; Production efficiency: The single-pass conversion rate of aluminum powder is 90.5%, which is 17.7 percentage points higher than that of traditional processes, reducing the number of times raw materials need to be added. Economic cost: The overall cost per ton of product is reduced by 1,500 yuan (including a 20% reduction in raw material loss and a 200 yuan saving in fuel costs). Retrofitting: The device can be connected to the existing reactor via flange / quick connector. The retrofitting cost is 28,000 yuan, the installation period is 2 days, and no production stoppage is required.

[0033] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A reflux apparatus for producing aluminum sec-butoxide, characterized in that, include: The reaction unit includes a jacketed reactor, a stirring assembly, and at least two temperature monitoring devices distributed along the height of the reactor. An integrated adsorption-condensation separation unit is connected in series at the gas phase outlet at the top of the reactor, and is provided with a primary adsorption section, a condensation section and a secondary adsorption section in sequence along the direction of mixed steam flow. The primary adsorption section is filled with 3A molecular sieve and the secondary adsorption section is filled with hydrophobic modified activated carbon. A directional reflux distribution unit is connected to the outlet of the adsorption-condensation integrated separation unit. It includes a main pipe and at least three branch pipes. The three branch pipes correspond to the bottom area of ​​the reactor, the stirring area in the reactor, and the liquid surface area at the top of the reactor, respectively. Each branch pipe is equipped with a nozzle adapted to the corresponding area at its end.

2. The reflux apparatus for producing aluminum sec-butoxide according to claim 1, characterized in that, In the integrated adsorption-condensation separation unit, a wire mesh demister is installed at the top of the primary adsorption section; the condensation section has a tubular structure, and circulating water at 20-30℃ is introduced into the shell side of the condensation section; a humidity sensor is installed at the outlet of the primary adsorption section, and an online refractometer is installed at the outlet of the secondary adsorption section.

3. The reflux apparatus for producing aluminum sec-butoxide according to claim 1, characterized in that, In the directional reflux distribution unit, an electromagnetic flowmeter is installed on the main pipeline; the three branch pipes are the bottom branch pipe, the middle branch pipe, and the top branch pipe. The bottom branch pipe is arranged in a circular array along the bottom of the reactor, with its end nozzle facing the center area of ​​the bottom of the reactor, and the nozzle installation position is 50-80mm from the bottom of the reactor; the middle branch pipe has an angled nozzle at its end, facing the area where the stirring assembly is located, and the horizontal distance between the nozzle and the stirring assembly is 100-150mm; the top branch pipe has an umbrella-shaped nozzle at its end, facing the liquid surface inside the reactor, and the installation position is 100-150mm from the liquid surface; each branch pipe is equipped with an electric regulating valve.

4. The reflux apparatus for producing aluminum sec-butoxide according to claim 1, characterized in that, In the reaction unit, the reactor is made of 316L stainless steel, and the jacket is filled with heat transfer oil at 50-120℃, with a temperature control accuracy of ±1℃. The stirring assembly is an anchor-type stirring paddle, the diameter of which is 0.6-0.8 times the diameter of the reactor, and the stirring assembly is equipped with a variable frequency motor with a speed of 50-300 r / min. The temperature monitoring device is a PT100 platinum resistance thermometer, the measurement range of which is 0-200℃, with an accuracy of ±0.5℃.

5. A reflux method for producing aluminum sec-butoxide, characterized in that, The reflux apparatus for producing aluminum sec-butoxide according to any one of claims 1-4 comprises the following steps: Pretreatment: Aluminum powder is mixed with iodine catalyst to obtain aluminum powder-catalyst mixture; industrial grade sec-butanol is preheated to obtain preheated sec-butanol; Reaction and reflux: a. Add aluminum powder-catalyst mixture and preheated sec-butanol into the reactor, turn on the jacket heating to raise the temperature inside the reactor to 95-100℃, so that the sec-butanol boils and generates mixed steam. b. The mixed steam enters the adsorption-condensation integrated separation unit, where it sequentially passes through the 3A molecular sieve in the primary adsorption section to adsorb water, the condensation section to condense it into liquid, and the hydrophobic modified activated carbon in the secondary adsorption section to adsorb isobutanol, resulting in a reflux liquid of sec-butanol with a purity ≥99.5%. c. The sec-butanol reflux liquid is sprayed through the three branch pipes of the directional reflux distribution unit. The bottom branch pipe sprays aluminum powder through a circumferential array of nozzles, the middle branch pipe sprays towards the stirring area through an oblique nozzle, and the top branch pipe sprays towards the liquid surface through an umbrella-shaped nozzle. Post-processing: The reaction continues until the purity of sec-butoxide aluminum in the reactor is ≥97.5%. The jacket temperature is then reduced to 40°C before discharge. At the same time, the 3A molecular sieve in the primary adsorption section and the hydrophobic modified activated carbon in the secondary adsorption section are regenerated.

6. The reflux method for producing aluminum sec-butoxide according to claim 5, characterized in that, In the pretreatment step, the aluminum powder has a purity of ≥99.5% and is crushed to 80-120 mesh; the amount of iodine catalyst added is 0.6-1.0 wt% of the aluminum powder mass; the industrial grade sec-butanol has a purity of ≥99% and is preheated to 55-65℃ by a waste heat exchanger.

7. The reflux method for producing aluminum sec-butoxide according to claim 5, characterized in that, In the reaction and reflux steps, in step a, the aluminum powder-catalyst mixture is added at a rate of 45-55 kg / 1000 L reactor volume, and the preheated sec-butanol is added at a rate of 330-370 kg / 1000 L reactor volume, with an initial stirring speed of 120-180 r / min; in step b, the humidity sensor shows that the humidity at the outlet of the first adsorption section is <5%RH, and the online refractometer shows that the sec-butanol concentration at the outlet of the second adsorption section is ≥99.8%; in step c, the initial distribution ratio of the sec-butanol reflux liquid is: 30-40% in the bottom region, 40-60% in the middle region, and 10-30% in the top region.

8. The reflux method for producing aluminum sec-butoxide according to claim 5, characterized in that, In the reaction and reflux steps, if the temperature monitoring device shows that the bottom temperature of the vessel is >103℃ after the reaction has been carried out for 4-5 hours, the distribution ratio of sec-butanol reflux liquid in the bottom branch pipe is increased to 35-45%, and the stirring speed is increased to 180-220 r / min; if the online refractometer shows that the sec-butanol concentration is <99.5%, the reflux is turned off, and the hydrophobic modified activated carbon in the secondary adsorption section is replaced.

9. The reflux method for producing aluminum sec-butoxide according to claim 5, characterized in that, In the post-processing steps, the regeneration conditions for 3A molecular sieve are hot air purging at 140-160℃ for 1.5-2.5h, and the regeneration conditions for hydrophobic modified activated carbon are saturated steam desorption at 110-130℃ for 25-35min. The hydrogen recovered in the hydrogen storage tank is used as fuel for the reactor jacket, and the proportion of hydrogen replacing natural gas is 15-25%.

Images