Apparatus for photocatalytic synthesis of tetradecyl fluoride refrigerant r1234ze

Abstract

The utility model discloses a kind of photocatalytic VDF synthesis fourth-generation refrigerant R1234ze's device, belong to chemical equipment technical field.The device includes catalyst preparation subsystem, reaction subsystem and product separation subsystem connected in turn.The catalyst preparation subsystem is realized the continuous production of catalyst by the series connection of raw material mixing kettle, hydrothermal reaction tower, centrifuge, vacuum dryer and heating rotary kiln;The reaction subsystem includes the reaction blending tank equipped with stirring device and the photocatalytic reaction tower of quartz material, and the reaction tower is equipped with xenon lamp array outside, is equipped with gas distribution plate and catalyst fixing device inside, and is equipped with gas circulation loop;The product separation subsystem is rectification separation device.The utility model realizes the whole-process continuous operation from catalyst preparation to product separation by integrated design, solves the problem that existing equipment is high in energy consumption, low in efficiency, cannot stable continuous production, with the advantages of reasonable structure, low energy consumption, high production efficiency.

Description

Technical Field

[0001] This utility model belongs to the field of green chemical technology, specifically relating to a device for photocatalytic VDF synthesis of fourth-generation refrigerant R1234ze. Background Technology

[0002] The fourth-generation refrigerant R1234ze (trans-1,3,3,3-tetrafluoropropylene), as an environmentally friendly refrigerant, has always been a focus of industry attention due to its industrial synthesis process and supporting equipment. Currently, its production mainly relies on two technical routes, but the corresponding equipment systems both have significant shortcomings.

[0003] First, traditional thermocatalytic synthesis devices dominate the market. The core of these devices is a fixed-bed or fluidized-bed reactor, designed to withstand reaction environments exceeding 400°C. This imposes extremely stringent requirements on reactor materials (such as special alloys), resulting in high equipment manufacturing costs. Furthermore, maintaining such high operating temperatures necessitates large and energy-intensive heating furnaces and heat tracing systems, leading to enormous energy consumption and high operating costs. In addition, increased side reactions at high temperatures necessitate the connection of complex and large multi-stage distillation columns, adsorption columns, and other separation and purification equipment, resulting in a long system flow, large footprint, and high initial investment and maintenance costs.

[0004] Secondly, to overcome the drawbacks of thermocatalysis, emerging photocatalytic synthesis technology has appeared. However, existing photocatalytic devices are mostly designed for laboratory research or are simply scaled-up batch reactors, making it difficult to meet the needs of continuous industrial production. Specifically: Missing or inefficient catalyst processing units: Most units lack integrated continuous catalyst preparation and recovery units. Catalysts are often added in batches, which can easily lead to agglomeration and sedimentation due to uneven stirring, resulting in decreased activity. Furthermore, they are difficult to recover and reuse, increasing raw material costs and potentially causing secondary pollution.

[0005] Poorly designed photoreactors: Common photoreactors, after being scaled up, generally suffer from problems such as unreasonable light source arrangement, uneven illumination, and low light energy utilization. Poor light transmittance or susceptibility to corrosion in the reactor material, coupled with inadequate internal flow field design, prevents efficient contact between reactants, catalysts, and the light source, resulting in reaction efficiency far lower than laboratory levels.

[0006] Poor system integration: The equipment for each process, such as catalyst preparation, reaction, and separation, is often independent and fragmented, failing to form a continuous and automated production line. Material transfer between units requires multiple conveying and temporary storage, which not only increases energy consumption and material loss but also makes it difficult to achieve precise control and large-scale stable operation of the entire production process.

[0007] Therefore, existing devices for synthesizing R1234ze, whether traditional high-temperature thermocatalytic systems or immature industrial photocatalytic devices, all suffer from structural defects such as high energy consumption, low efficiency, poor integration, and difficulty in continuous and stable operation. Developing a dedicated synthesis device capable of catalyst self-sufficiency, efficient light energy utilization, and full-process continuous automation has become an urgent equipment requirement for promoting the large-scale production of this environmentally friendly refrigerant. Utility Model Content

[0008] To address the problems existing in the above-mentioned background technology, this utility model provides an industrial device for the photocatalytic synthesis of R1234ze from VDF. This device aims to achieve continuous and integrated operation of the entire process of catalyst preparation, photocatalytic reaction and product separation through optimized structural design, thereby effectively improving production efficiency and reducing energy consumption and operating costs.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: An apparatus for photocatalytic VDF synthesis of fourth-generation refrigerant R1234ze includes a catalyst preparation subsystem, a reaction subsystem, and a product separation subsystem, which are connected sequentially by pipelines to form a continuous production line.

[0010] The catalyst preparation subsystem comprises a raw material mixing vessel, a hydrothermal reaction tower, a centrifuge, a vacuum dryer, and a heated rotary kiln, all connected sequentially by pipelines. The subsystem's design enables continuous production of the catalyst throughout the entire process, from raw material mixing, hydrothermal synthesis, solid-liquid separation, drying to high-temperature activation, ensuring stable and consistent catalyst quality.

[0011] The reaction subsystem includes a reaction mixing tank and a photocatalytic reaction tower. The reaction mixing tank is equipped with a stirring device for uniformly preparing the reaction solution. The photocatalytic reaction tower is made of quartz glass and is surrounded by an array of xenon lamps providing uniform illumination. Inside, it contains a gas distribution plate and a fixing device for securing the catalyst. A photocatalytic reaction tower circulation pump is connected to the bottom of the tower via a pipe to form a circulation loop for the reaction gas. This subsystem structure ensures efficient contact between the reactants, catalyst, and light source, and the continuous progress of the reaction process.

[0012] The product separation subsystem includes a distillation separation device connected to the outlet of the photocatalytic reaction tower, used to separate and purify the mixture after the reaction to directly obtain a high-purity product.

[0013] Furthermore, in the catalyst preparation subsystem, the raw material mixing vessel is connected to a g-C3N4 precursor storage tank, a BiVO4 precursor storage tank, and a deionized water storage tank via pipelines, thereby realizing automatic supply and precise proportioning of raw materials.

[0014] Furthermore, the hydrothermal reaction tower is connected to the raw material mixing vessel via a hydrothermal reaction tower feed pump, ensuring that the precursor solution is stably delivered to the high-pressure reaction environment.

[0015] Furthermore, in the catalyst preparation subsystem, the inlet of the centrifuge is connected to the outlet of the hydrothermal reaction tower; the inlet of the vacuum dryer is connected to the solid outlet of the centrifuge; the inlet of the heated rotary kiln is connected to the outlet of the vacuum dryer, and its outlet is connected to the finished catalyst storage tank. This structure forms a closed, continuous flow of catalyst material from synthesis to collection.

[0016] Furthermore, the reaction subsystem is also equipped with a catalyst delivery blower, whose inlet is connected to the finished catalyst storage tank and whose outlet is connected to the reaction mixing tank. This structure enables the automatic and uniform addition and dispersion of the finished catalyst.

[0017] Furthermore, the photocatalytic reaction tower is also equipped with a heating electrode, which is connected to a power source for precise temperature control of the reaction system.

[0018] Furthermore, the hydrothermal reaction tower is connected to a hydrothermal reaction tower circulation system, which includes a hydrothermal reaction tower circulation tank and a hydrothermal reaction tower circulation pump, to enhance the mixing and temperature uniformity of materials within the tower.

[0019] Compared with the prior art, the present invention has the following significant advantages: 1. High integration and continuity: This utility model organically integrates the three functional modules of catalyst preparation, reaction and separation to form a complete closed continuous production line. It overcomes the drawbacks of traditional equipment with fragmented units and batch operation, greatly improves production efficiency and automation level, and provides equipment foundation for large-scale stable production.

[0020] 2. Significantly reduced energy consumption and operating costs: The core of the device adopts a low-temperature photocatalytic reaction tower, replacing the traditional high-temperature thermocatalytic reactor, fundamentally avoiding the huge energy consumption caused by high-temperature heating. The integrated design also reduces energy losses during material transfer and intermediate storage.

[0021] 3. Improved Reaction Efficiency and Stability: The dedicated quartz photocatalytic reaction tower structure, combined with the built-in gas distribution plate, catalyst fixing device, and external light homogenization system, ensures efficient contact and reaction between light, reactants, and catalyst. The integrated catalyst circulation preparation and dosing system guarantees the activity and stability of the catalyst supply, thereby ensuring the continuous and efficient operation of the entire system.

[0022] 4. Enhanced equipment reliability and lifespan: Each subsystem equipment is selected and designed according to its process characteristics (such as corrosion-resistant alloy hydrothermal reaction tower, quartz reaction tower, etc.), with a reasonable structure, which reduces equipment wear and failure rate and extends the service life of the entire set of equipment. Attached Figure Description

[0023] Figure 1 This is a structural diagram of the apparatus for photocatalytic VDF synthesis of fourth-generation refrigerant R1234ze according to this invention.

[0024] In the diagram, 1-raw material mixing vessel; 1.1-g-C3N4 precursor storage tank; 1.2-g-C3N4 precursor metering pump; 1.3-BiVO4 precursor storage tank; 1.4-BiVO4 precursor metering pump; 1.5-deionized water storage tank; 1.6-deionized water metering pump; 1.7-mixing vessel stirrer; 1.8-hydrothermal reaction tower feed pump; 2-hydrothermal reaction tower; 2.1-high-pressure steam regulating valve; 2.2-hydrothermal reaction tower circulation tank; 2.3-hydrothermal reaction tower circulation pump; 3-centrifuge; 4-vacuum dryer 5-Heating rotary kiln; 5.1-Natural gas pipeline; 6-Finished catalyst storage tank; 7-Catalyst conveying blower; 8-VDF storage tank; 9-VDF metering pump; 10-Reaction mixing tank; 10.1-Mixing tank mixer; 10.2-Photocatalytic reaction tower feed pump; 11-Photocatalytic reaction tower; 11.1-Hydrogen lamp array; 11.2-Gas distributor; 11.3-Heating electrode; 11.4-Power supply; 12-Photocatalytic reaction tower circulation pump; 13-Distillation separation unit. Detailed Implementation

[0025] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. These descriptions are not intended to limit the scope of protection of the present invention, but rather to better illustrate its essential content.

[0026] This invention provides a device for photocatalytic VDF synthesis of fourth-generation refrigerant R1234ze, as shown in the attached diagram. Figure 1 As shown, the device mainly includes a catalyst preparation subsystem, a reaction subsystem, and a product separation subsystem connected in sequence.

[0027] 1. Catalyst Preparation Subsystem This subsystem is used for the continuous preparation of g-C3N4 / BiVO4 heterojunction photocatalysts. Its core equipment includes a raw material mixing vessel 1, a hydrothermal reaction tower 2, a centrifuge 3, a vacuum dryer 4, and a heated rotary kiln 5. These devices are connected sequentially through pipelines and delivery pumps.

[0028] Raw material mixing vessel 1 is made of stainless steel and has a volume of 5-10m³. 3The upper part is connected via pipes to a g-C3N4 precursor storage tank 1.1, a BiVO4 precursor storage tank 1.3, and a deionized water storage tank 1.5. Each storage tank outlet is equipped with a high-precision metering pump (1.2, 1.4, 1.6) for precise control of raw material dosage. The raw material mixing vessel 1 is equipped with a high-power mechanical agitator (mixing vessel agitator) 1.7 driven by a motor, with a speed range of 150-300 rpm, ensuring thorough mixing of materials.

[0029] The hydrothermal reaction tower 2 is a high-temperature and high-pressure resistant alloy steel device, designed to withstand pressures of 20-30 MPa. Its inlet is connected to the outlet of the raw material mixing vessel 1 via a hydrothermal reaction tower feed pump 1.8. The hydrothermal reaction tower 2 is connected to a circulating temperature control system, which includes a high-pressure steam regulating valve 2.1, a hydrothermal reaction tower circulation tank 2.2, and a hydrothermal reaction tower circulation pump 2.3. This circulation system allows for precise control of the reaction temperature within the tower between 170-200℃.

[0030] Centrifuge 3 is a high-speed disc centrifuge, with 4-6 units connected in series, and the speed can reach 10,000-13,000 rpm. Its inlet is connected to the outlet of the hydrothermal reaction tower 2, and it is used to separate the hydrothermal reaction products into solid and liquid components.

[0031] The inlet of the vacuum dryer 4 is connected to the solid outlet of the centrifuge 3. The working vacuum of the vacuum dryer 4 can be adjusted between 30-70 Pa, and the temperature is maintained between 88-92℃.

[0032] The feed inlet of the heated rotary kiln 5 is connected to the discharge outlet of the vacuum dryer 4 via a screw conveyor. The heated rotary kiln 5 can be heated by natural gas or electricity and is equipped with a precise temperature control system. Its discharge outlet is ultimately connected to the finished catalyst storage tank 6, where the prepared catalyst is stored for later use.

[0033] 2. Reaction Subsystem This subsystem is used for photocatalytic reactions and mainly includes a reaction mixing tank 10 and a photocatalytic reaction tower 11.

[0034] The reaction mixing tank 10 has a volume of 15-20m³. 3 Made of carbon steel lined with polytetrafluoroethylene, it has good corrosion resistance. A VDF gas inlet is located on the top of the tank, connected to a VDF storage tank 8 and a VDF metering pump 9 via pipeline. The tank is equipped with a mixing tank agitator 10.1, with a speed control range of 200-250 rpm. The tank also integrates an online gas chromatography analysis system and an automatic pH adjustment device (not shown in the figure) for real-time monitoring and adjustment of the reaction solution concentration and pH.

[0035] The photocatalytic reaction tower 11 is the core of the entire device. Its body is made of high-purity quartz glass, cylindrical in shape, with a height between 8-12m and a diameter between 4-8m. A light array consisting of multiple sets of high-power xenon lamps 11.1 is arranged around the tower body, providing a light power density of 130-170 mW / cm². 2 The tower simulates sunlight (AM1.5G spectrum). Inside, multiple specially designed gas distribution plates 11.2 are installed from top to bottom, with pore sizes precisely controlled between 0.3-1.5 mm to ensure uniform distribution of the reactant gases. A catalyst fixing device (not shown in the figure) composed of stainless steel wire mesh and a ceramic coating is also installed inside the tower to support and fix the photocatalyst. A heating electrode 11.3 is located at the bottom of the tower, which is connected to an external power supply 11.4 to form a temperature control system that can precisely control the reaction temperature at 80±1℃. The gas outlet at the bottom of the tower is connected to the inlet of the photocatalytic reaction tower circulation pump 12 via a pipe. The outlet of this pump is connected to the gas return port at the bottom of the tower, thus forming a closed gas circulation loop with a circulation velocity controlled at 24-26 m / s. 3 / h.

[0036] The reaction subsystem also includes a catalyst delivery blower 7, whose inlet is connected to the finished catalyst storage tank 6 via a pipeline, and whose outlet is connected to the reaction mixing tank 10 via pipelines, thereby achieving automatic and uniform catalyst addition. The outlet of the reaction mixing tank 10 is connected to the inlet of the photocatalytic reaction tower 11 via the photocatalytic reaction tower feed pump 10.2.

[0037] 3. Product separation subsystem This subsystem is relatively independent and has a mature structure, mainly including a distillation and separation unit 13. The inlet of this unit is directly connected to the liquid outlet at the bottom of the photocatalytic reaction tower 11 through a pipeline, which is used to separate and purify the mixture after the reaction, and finally obtain a high-purity R1234ze product.

[0038] The working process of this utility model device is as follows: I. Industrial preparation of g-C3N4 / BiVO4 heterojunction photocatalysts 1. Raw material pretreatment and mixing: With a volume of 8m 3In a stainless steel raw material mixing vessel 1, 800 kg of high-purity melamine (as a g-C3N4 precursor, with an impurity content of <0.03%) was accurately weighed using a high-precision metering pump and transferred from the g-C3N4 precursor storage tank 1.1 to the mixing vessel via g-C3N4 precursor metering pump 1.2. Simultaneously, 3200 kg of pre-prepared BiVO4 precursor (prepared from bismuth nitrate pentahydrate and ammonium metavanadate in a stoichiometric ratio and stored in BiVO4 precursor storage tank 1.3) was accurately weighed and transferred to the mixing vessel via BiVO4 precursor metering pump 1.4. Subsequently, 4000 L of deionized water with a conductivity of less than 0.3 μS / cm was added from the deionized water storage tank 1.5 via deionized water metering pump 1.6. The mixing vessel stirring unit 1.7 was started and continuously stirred at 250 rpm for 50 minutes to ensure that all raw materials were uniformly mixed at both the macroscopic and microscopic levels, forming a stable precursor suspension.

[0039] 2. Continuous high-pressure hydrothermal reaction: The homogeneously mixed precursor solution was pumped into a continuous high-pressure hydrothermal reactor 2 at a flow rate of 10 L / h via a feed pump 1.8. This reactor is lined with a corrosion-resistant special alloy. A precise temperature control system was activated, raising the reactor temperature to 180°C at a rate of 8°C / min and maintaining this temperature for 18 hours, while the system pressure remained stable at 25 MPa. During this process, a portion of the reaction liquid temporarily stored in the circulating tank 2.2 was circulated back to the top of the hydrothermal reactor 2 via a circulating pump 2.3 to enhance the mixing effect of the raw materials. The amount of steam entering the circulating tank was precisely controlled using a high-pressure steam regulating valve 2.1 to maintain a constant reaction temperature and improve reaction efficiency. This step aims to construct a g-C3N4 / BiVO4 heterojunction structure in situ.

[0040] 3. Industrial-scale multi-stage purification and drying: After the hydrothermal reaction, the resulting product mixture flows through pipelines into a multi-stage centrifugal separation system consisting of five centrifuges connected in series. The centrifuges are set to 10,000 rpm, and through continuous centrifugation, unreacted raw materials and soluble impurity ions are efficiently separated and removed. The solid precipitate after centrifugation is collected and transported to a large vacuum dryer, where it is continuously dried for 15 hours at 90°C and a vacuum of 50 Pa, reducing the moisture content of the material to below 0.2%, thus obtaining a dried catalyst precursor.

[0041] 4. Large-scale, precise calcination and activation: The dried catalyst precursor is uniformly fed into the heated rotary kiln 5 via an automated conveyor belt. The rotary kiln is heated by natural gas (supplying from pipeline 5.1), and the temperature is steadily increased to 400℃ at a rate of 7℃ / min using a high-precision temperature control system, where it is calcined for 2 hours. This process aims to optimize the crystal structure of the catalyst, generate a large number of highly active sites, and significantly improve its photocatalytic performance. After calcination, the product is naturally cooled to room temperature inside the furnace and finally collected by a discharge device to obtain the g-C3N4 / BiVO4 heterojunction photocatalyst product, which is stored in a moisture-proof and oxidation-proof finished catalyst storage tank 6 for later use.

[0042] II. Industrial-scale reaction for photocatalytic synthesis of R1234ze 1. Preparation of reaction solution: With a volume of 18m 3 In a large, sealed reaction mixing tank 10, 50,000 L of deeply purified deionized water (conductivity ≤ 0.3 μS / cm) is first added. The mixing tank agitator 10.1 is started, with the speed controlled at 200 rpm. Under low-temperature (0-2℃) and light-protected conditions, 5,000 L of high-purity VDF gas (purity ≥ 99.8%) stored in the VDF metering tank 8 is slowly and evenly introduced into the water via the VDF metering pump 9 to ensure complete dissolution. The VDF concentration is monitored in real time using an integrated online gas chromatography system, and its concentration is precisely adjusted to 0.1 mol / L by adding VDF or deionized water. Subsequently, an industrial-grade automatic acid-base adjustment device is activated, and dilute hydrochloric acid solution is slowly added dropwise to precisely control the pH of the reaction solution to 6.0.

[0043] 2. Catalyst addition and reaction start-up: 1400 kg (i.e., 7.8 kg per cubic meter of reaction solution) of the g-C3N4 / BiVO4 heterojunction photocatalyst prepared in Example 1 was uniformly dispersed into the above reaction solution using a pneumatic conveying system powered by a catalyst conveying blower 7. Subsequently, the mixture was pumped entirely into a large quartz photocatalytic reaction tower 11 using a photocatalytic reaction tower feed pump 10.2.

[0044] 3. Light and reaction process control: Turn on the high-power xenon lamp array 11.1 surrounding the reaction tower, and adjust the optical system to stabilize the light power density in the reaction zone inside the tower at 150 mW / cm². 2 The spectrum is the AM1.5G standard solar spectrum. Simultaneously, a multi-stage temperature control system consisting of heating electrode 11.3, power supply 11.4, temperature sensor, and heat exchanger is activated to precisely control the reaction temperature at 80℃ (error ±1℃). The photocatalytic reaction tower circulation pump 12 is started, causing the reaction gas (a mixture of VDF and HCl) to flow at a rate of 25m...3 The flow rate is continuously circulated within the column and uniformly distributed through the gas distribution plate 11.2 to ensure sufficient contact with the catalyst fixed within the column.

[0045] During the reaction, an online gas chromatography-mass spectrometry (GC-MS) system automatically takes samples from different heights of the reaction tower every 45 minutes to analyze the product composition and concentration in real time. Based on the feedback data, the system automatically fine-tunes parameters such as gas flow rate and temperature to optimize the reaction.

[0046] 4. Product separation and collection: After 5 hours of continuous reaction, online monitoring showed that the yield and purity of R1234ze had reached the predetermined standards. At this point, illumination and gas circulation were stopped, and the product mixture at the bottom of the reaction tower was discharged and introduced into the distillation separation unit 13 for separation and purification. Finally, high-purity R1234ze product was obtained through distillation.

Claims

1. An apparatus for photocatalytic VDF synthesis of fourth-generation refrigerant R1234ze, characterized in that, The device comprises a catalyst preparation subsystem, a reaction subsystem, and a product separation subsystem connected in sequence. The catalyst preparation subsystem includes a raw material mixing vessel (1), a hydrothermal reaction tower (2), a centrifuge (3), a vacuum dryer (4), and a heated rotary kiln (5) connected sequentially by pipelines. The reaction subsystem includes a reaction mixing tank (10) and a photocatalytic reaction tower (11). The reaction mixing tank (10) is equipped with a mixing tank stirrer (10.1). The photocatalytic reaction tower (11) is made of quartz glass and is surrounded by a xenon lamp array (11.1). It is equipped with a gas distribution plate (11.2) and a catalyst fixing device inside. The bottom of the tower is connected to a photocatalytic reaction tower circulation pump (12) through a pipe. The product separation subsystem includes a distillation separation device (13) connected to the outlet of the photocatalytic reaction tower (11).

2. The apparatus according to claim 1, characterized in that, In the catalyst preparation subsystem, the raw material mixing vessel (1) is connected to a g-C3N4 precursor storage tank (1.1), a BiVO4 precursor storage tank (1.3), and a deionized water storage tank (1.5) via pipelines, and is equipped with a mixing vessel agitator (1.7).

3. The apparatus according to claim 2, characterized in that, The hydrothermal reaction tower (2) is connected to the raw material mixing vessel (1) via the hydrothermal reaction tower feed pump (1.8).

4. The apparatus according to claim 1, characterized in that, In the catalyst preparation subsystem, the inlet of the centrifuge (3) is connected to the outlet of the hydrothermal reaction tower (2); the inlet of the vacuum dryer (4) is connected to the solid outlet of the centrifuge (3); the inlet of the heating rotary kiln (5) is connected to the outlet of the vacuum dryer (4), and its outlet is connected to the finished catalyst storage tank (6).

5. The apparatus according to claim 1, characterized in that, In the reaction subsystem, the reaction mixing tank (10) is connected to the photocatalytic reaction tower (11) via the photocatalytic reaction tower feed pump (10.2).

6. The apparatus according to claim 1 or 5, characterized in that, The reaction subsystem is also equipped with a catalyst conveying blower (7), the inlet of which is connected to the finished catalyst storage tank (6), and the outlet is connected to the reaction mixing tank (10).

7. The apparatus according to claim 1, characterized in that, The photocatalytic reaction tower (11) is also equipped with a heating electrode (11.3), which is connected to a power source (11.4).

8. The apparatus according to claim 1, characterized in that, The hydrothermal reaction tower (2) is connected to a hydrothermal reaction tower circulation system, which includes a hydrothermal reaction tower circulation tank (2.2) and a hydrothermal reaction tower circulation pump (2.3).

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