System and method for preparing butadiene by electrolyzing calcium carbide acetylene

Abstract

The invention discloses a system and a method for preparing butadiene by electrolyzing calcium carbide acetylene. The system comprises an acetylene generation device, an electrolytic bath and a product separation system which are connected in sequence, the electrolytic bath adopts a gas diffusion negative electrode and a nickel foam positive electrode. According to the method, by controlling the cathode potential to be-0.2 V to-0.6 V vs. RHE and the acetylene gas velocity to be 10-100 sccm, efficient electrocatalytic coupling of acetylene is achieved, the butadiene Faraday efficiency reaches 68% or above, the current density is not lower than 80 mA / cm < 2 >, and hydrogen and oxygen are byproducts. According to the invention, through system integration and process optimization, acetylene mass transfer limitation is broken through, and green and continuous production of coal-based butadiene is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of chemical process and electrochemical synthesis technology, in particular to a system and method for preparing butadiene by electrolysis of calcium carbide acetylene. BACKGROUND

[0002] 1,3-butadiene is a key monomer for the synthesis of rubber and engineering plastics (such as ABS resin and nylon 66), and has a huge market demand. Currently, its industrial production almost completely relies on the extraction method of C4 fraction byproduct of naphtha steam cracking, and the raw material is subject to petroleum resources, and the process flow is long and the energy consumption is high.

[0003] It is of great significance to develop a butadiene synthesis process that is not dependent on petroleum. Based on China's energy endowment of "rich in coal, poor in oil, and less gas", using coal-based raw materials to prepare butadiene is an extremely attractive path. The applicant's company has successfully developed and industrialized two internationally leading technologies: ① using methanol as raw material to prepare hydrocyanic acid, and then reacting with butadiene to form adiponitrile; ② one-step preparation of calcium carbide from coal. Technology ② replaces the traditional calcium carbide production process with high energy consumption, providing a low-cost and green raw material basis for acetylene chemical industry. In order to build a complete "coal-adiponitrile" industrial chain, it is urgent to develop a highly efficient and green butadiene production technology that can be integrated with technology ②.

[0004] Acetylene as a potential raw material for the production of butadiene has attracted attention in recent years, but most of the research is in the laboratory. For example: Chinese patent CN120591828A discloses a method for electrocatalytic reduction of acetylene to butadiene using copper hydroxide hydrophobic nanoarray, the core innovation of which is the structure of the cathode catalyst, aiming to improve the selectivity. However, this technology still uses traditional H-type electrolytic cell, and the mass transfer efficiency of acetylene gas in the liquid phase is low, which makes it difficult to improve the current density, and it does not involve a complete industrialization system; Chinese patent CN112342562A and Chinese patent CN118186408A both propose the use of gas diffusion electrode (GDE) for acetylene electrocatalysis, recognizing the importance of GDE in improving gas phase mass transfer. However, the focus of these two documents is still on the electrode itself or the catalyst formulation, and they do not disclose a complete process system that can be efficiently integrated with the upstream calcium carbide acetylene generation device and the downstream product separation system, and can be continuously operated.

[0005] Therefore, there is a significant gap in the existing technology. Specifically: Although patent CN112342562A uses a gas diffusion electrode, its system does not integrate a calcium carbide acetylene generation device, and the current density is less than 50 mA / cm 2 , which cannot realize industrial continuous production; Patent CN118186408A focuses on Fe / Co catalyst optimization, but the electrolytic cell design is limited to laboratory scale, lacks a product separation system, and the acetylene conversion rate is less than 50%; Patent CN120591828A improves selectivity through hydrophobic nanoarrays, but uses a traditional H-type electrolytic cell with low mass transfer efficiency and a current density less than 30 mA / cm 2 .

[0006] In summary, the existing technologies have not solved the problems of low acetylene mass transfer efficiency and poor system integration, making it difficult to support the industrialization of coal-based butadiene.

[0007] In summary, the defects of the existing technologies are rooted in systematic fragmentation, which fails to integrate and cooperatively control the three core links of coal-based calcium carbide acetylene generation, gas diffusion electrode electrolysis suitable for acetylene gas phase reaction, and online separation of multi-component products. This fragmentation leads to mutual exclusion of individual unit performance, forming a "bucket effect". Even if individual units (such as electrodes) are improved, the overall process still cannot achieve continuous, stable, and efficient industrial operation.

[0008] More specifically, the technical obstacles existing in the prior art are as follows: first, the instability caused by system fragmentation, the combination of steel cylinder gas source and isolated electrolytic cell cannot guarantee the stability of gas composition and pressure, leading to fluctuation of reaction efficiency and inability to run long-term (see Comparative Example 1 below); second, the low production efficiency caused by mass transfer limitation, the use of traditional H-type electrolytic cell even with high-efficiency catalyst cannot obtain high current density (>50 mA / cm 2 ), thus lacking economic feasibility (see Comparative Example 2 below); third, the lack of a full-process green process design for the coal-based calcium carbide route, making it difficult to achieve seamless connection from raw materials to products and maximize the value of by-products. The fundamental purpose of the present invention is to overcome the above three obstacles and provide a complete solution that can be truly industrialized. SUMMARY

[0009] In view of the above technical problems existing in the prior art, in order to solve the deficiencies of the prior art, the present invention aims to provide a system and method for preparing butadiene from calcium carbide acetylene electrolysis, which can achieve efficient electrocatalytic conversion of acetylene, continuous process flow, low energy consumption, and high product selectivity, thereby solving the deficiencies of the prior art.

[0010] This invention provides a continuous production system for preparing butadiene from calcium carbide acetylene by electrolysis: It includes an acetylene generator, an electrolytic cell, and a product separation system connected in sequence. The outlet of the acetylene generator is connected to the gas inlet of the cathode chamber of the electrolytic cell; the outlet of the cathode chamber of the electrolytic cell is connected to the inlet of the product separation system; the electrolytic cell includes a cathode chamber and an anode chamber separated by a diaphragm; a gas diffusion cathode electrode is disposed in the cathode chamber; a nickel foam anode is disposed in the anode chamber, the purity of the nickel foam anode being not less than 99.5% and the pore size being 300-800 μm. The gas diffusion cathode electrode includes a hydrophobic conductive substrate and a catalyst layer supported thereon. This structure enables the construction of a stable three-phase reaction interface between gaseous acetylene, liquid electrolyte, and solid catalyst, which is key to achieving efficient electrocatalytic conversion of acetylene at high current densities.

[0011] As a further technical solution of the present invention: the catalyst of the gas diffusion cathode includes one or more of copper, silver, and palladium, which is loaded on a conductive substrate at a loading of 0.5-2.0 mg / cm³. 2 .

[0012] As a further technical solution of the present invention: the system also includes a cathode electrolyte preparation tank and an anode electrolyte preparation tank, which are connected to the cathode chamber and the anode chamber respectively through a circulation pump, and the circulation flow rate is 20-50 mL / min.

[0013] As a further technical solution of the present invention: the product separation system includes a gas-liquid separator and a distillation column for separating butadiene, hydrogen, ethylene and oxygen.

[0014] The present invention also provides a method for preparing butadiene using a system for preparing butadiene by electrolysis of calcium carbide and acetylene, comprising the following steps: S1. React calcium carbide and water in an acetylene generator to produce acetylene gas with a purity >98%. S2. The acetylene gas is continuously introduced into the cathode chamber of the electrolytic cell at a flow rate of 10-100 sccm, while the cathode potential of the cathode chamber is controlled to be -0.2V to -0.6V (relative to the reversible hydrogen electrode), so that the cathode current density is maintained at 80-150 mA / cm. 2 ; S3. The product output from the cathode chamber is sent into the separation system to obtain butadiene, hydrogen and ethylene; oxygen is output from the anode chamber.

[0015] Further: In step S2, both the cathode electrolyte and the anolyte are 0.1-5M KOH solutions, and the temperature is maintained at 20-40℃.

[0016] Furthermore: In step S3, the butadiene Faraday efficiency is >68% and the hydrogen purity is >98%.

[0017] Furthermore, the method also includes an online monitoring unit for real-time analysis of product composition and energy consumption.

[0018] The core technical solution of this invention is as follows: (1) System integration innovation: The calcium carbide acetylene generator, the electrolytic cell (with a gas diffusion electrode in the cathode chamber and a nickel foam anode in the anode chamber) and the product separation system are connected sequentially to form a closed loop. The catalyst of the gas diffusion electrode includes one or more of copper, silver and palladium, which are supported on a conductive substrate; the nickel foam anode is a commercially available high-purity material (e.g., 99.5% purity, 500μm pore size). (2) Method innovation: By controlling the cathode potential from -0.2V to -0.6V (relative to the reversible hydrogen electrode), the acetylene gas velocity from 10 to 100 sccm, and the current density from 80 to 150 mA / cm 2 This enables efficient coupling of acetylene at the gas-electrolyte-catalyst three-phase interface, with butadiene Faraday efficiency >68% and by-product hydrogen purity >98%.

[0019] Through in-depth research, the applicant recognized that to industrialize the electrocatalytic coupling of acetylene to butadiene, it is essential to break down the barriers between individual unit operations. The system integration of this invention is not a simple series connection of components, but rather a synergistic design that enhances and matches the 'reaction-transfer-separation' process. Specifically, the pressure and purity of the acetylene gas directly generated from calcium carbide are stably controlled through the generating device, providing a stable and reliable gas source for the gas diffusion electrode. The gas diffusion electrode fully utilizes this stable gas source, creating a highly efficient three-phase interface and achieving an increased intrinsic reaction rate at high current densities. Timely removal and separation of products (such as butadiene and ethylene) from the reaction zone not only improves the yield but also avoids secondary reactions or accumulation of products within the electrolyzer, which could inhibit catalyst activity. It is this organic integration based on deep technological understanding that enables the overall system to achieve a synergistic effect of '1+1>2,' solving a long-standing bottleneck problem that has constrained the development of this technology.

[0020] It should be noted that the catalysts described in this invention include, but are not limited to, copper, silver, and palladium. Those skilled in the art can select the appropriate catalyst based on different requirements for product selectivity. Copper-based catalysts exhibit the best selectivity for butadiene formation. The current density range is 80-150 mA / cm². 2 It covers the entire process from startup and optimization to enhanced production. Within the stated potential range, the current density matches the acetylene mass transfer rate, enabling efficient reactions.

[0021] Compared with the prior art, the beneficial effects of the present invention are: (1) High selectivity and high efficiency: Due to the use of a gas diffusion electrode and its direct coupling with the upstream acetylene generator, the three-phase contact efficiency between gaseous acetylene, catalyst, and electrolyte is greatly improved, breaking through the mass transfer limitation of traditional liquid-phase diffusion, enabling the reaction to proceed at high current densities (80-150 mA / cm²). 2 The butadiene Faradaic efficiency reached 68%-70% under these conditions. (2) Green and low-carbon: The reaction is carried out at room temperature and pressure, and the energy consumption is reduced by more than 30% compared with traditional thermocatalysis (such as the extraction of C4 fraction by-products from naphtha cracking, with a typical energy consumption of about 2.5-2.9 kWh / kg butadiene), reaching 1.70-2.03 kWh / kg butadiene; the purity of the oxygen by-product at the anode is >99.5%, and the hydrogen by-product at the cathode can be recycled; (3) Industrial chain synergy: This process can be perfectly integrated with the "coal-to-calcium carbide" technology to form a complete industrial chain of "coal-calcium carbide-acetylene-butadiene", reducing dependence on oil and conforming to the national energy strategy; (4) Continuous production: The system has a high degree of integration and can achieve continuous operation for more than 100 hours, with product purity of more than 99%; (5) Compared with the closest prior art (such as CN112342562A), the present invention, through complete system integration, reduces the reaction current density from less than 50 mA / cm² under the same catalyst conditions. 2 Increased to 80-150 mA / cm 2 The operable range is expanded, butadiene faradaic efficiency is increased by more than 13% (from 55% to more than 68% in this invention), reaching a new level, and seamless connection between upstream raw materials and downstream products is achieved, solving the key problem of its inability to be continuously produced. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the process flow of the system described in this invention. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Please refer to the instruction manual appendix. Figure 1This invention provides a technical solution: a continuous production system for preparing butadiene from calcium carbide acetylene electrolysis, comprising an acetylene generator, an electrolytic cell, and a product separation system connected in sequence. The outlet of the acetylene generator is connected to the gas inlet of the cathode chamber of the electrolytic cell; the outlet of the cathode chamber of the electrolytic cell is connected to the inlet of the product separation system; the electrolytic cell includes a cathode chamber and an anode chamber separated by a diaphragm; a gas diffusion cathode electrode is disposed in the cathode chamber; a nickel foam anode is disposed in the anode chamber, the purity of the nickel foam anode being not less than 99.5% and the pore size being 300-800 μm. The gas diffusion cathode electrode comprises a hydrophobic conductive substrate and a catalyst layer supported thereon. This structure can construct a stable three-phase reaction interface between gaseous acetylene, liquid electrolyte, and solid catalyst, which is key to achieving efficient electrocatalytic conversion of acetylene at high current densities.

[0025] As a further technical solution of the present invention: the catalyst of the gas diffusion cathode includes one or more of copper, silver, and palladium, which is loaded on a conductive substrate at a loading of 0.5-2.0 mg / cm³. 2 .

[0026] As a further technical solution of the present invention: the system also includes a cathode electrolyte preparation tank and an anode electrolyte preparation tank, which are connected to the cathode chamber and the anode chamber respectively through a circulation pump, and the circulation flow rate is 20-50 mL / min.

[0027] As a further technical solution of the present invention: the product separation system includes a gas-liquid separator and a distillation column for separating butadiene, hydrogen, ethylene and oxygen.

[0028] Example 1: System Setup and Initial Operation

[0029] 1. System Assembly: According to Figure 1 The system setup shown is as follows. The cathode of the electrolytic cell uses a carbon paper gas diffusion electrode loaded with Cu(OH)₂ nanocatalyst (catalyst loading 1.0 mg / cm²). 2 The anode uses commercially available nickel foam (99.5% purity, 500 μm pore size). The anode and cathode chambers are separated by anion exchange membranes (Fumasep FAA-3). The cathode electrolyte is a 1M KOH aqueous solution, and the anode electrolyte is a 1M KOH aqueous solution, both circulated by a circulation pump (model: Longer Pump BT100-2J) at a flow rate of 30 mL / min. In this invention, the pore size of the nickel foam anode is selected as 300-800 μm, an optimized range obtained through extensive experimental verification. A pore size that is too small (e.g., <300 μm) will increase the resistance to bubble release, leading to an increase in anode overpotential; a pore size that is too large (e.g., >800 μm) will reduce the effective reaction area and decrease current efficiency. The 500 μm pore size used in the examples is a preferred embodiment within this range.

[0030] 2. Raw material preparation: Add lumpy calcium carbide (CaC2, purity >95%) to the acetylene generator (stainless steel reactor, volume 5L).

[0031] 3. Reaction Process: Water is added dropwise to the acetylene generator to control the acetylene gas generation rate, producing acetylene gas (approximately 98% purity). This gas is then introduced into the cathode chamber of the electrolytic cell at a flow rate of 40 sccm. At room temperature (25℃), a constant current (power supply: Keithley 2230-30-1) is applied to the electrolytic cell to ensure a cathode current density of 80 mA / cm². 2 The cathode potential is (-0.4) to (-0.45V) vs. RHE (reference electrode: Hg / HgO).

[0032] Product Analysis: After the reaction had stabilized for 2 hours, the gas exiting the cathode chamber was collected and analyzed using an online gas chromatograph (Agilent 7890B, equipped with FID and TCD detectors). The Faraday efficiency (FE) is calculated as follows: Where n is the number of moles of the target product (mol), z is the number of electrons transferred (z=2 for butadiene), F is the Faraday constant (96485 C / mol), I is the current (A), and t is the time (s). The results showed that the Faraday efficiency for butadiene was 68.2% (mean, standard deviation ±0.5%), for ethylene it was 17.8%, and for hydrogen it was 8.1%. The outlet gas from the anode chamber was detected to be oxygen with a purity exceeding 99.5%. After 100 hours of continuous operation, the butadiene yield stability was >95% (relative standard deviation <3%), and the energy consumption was 1.7 kWh / kg butadiene.

[0033] Example 2: Optimization of Process Parameters Based on the system described in Example 1, with a fixed acetylene gas velocity of 40 sccm, the reaction performance was optimized by adjusting the cathode potential. Specific test conditions and results are shown in the table below: Table 1. Effect of cathode potential on reaction performance Cathode potential (V vs. RHE) Current density (mA / cm 2 ) Butadiene Faradaic efficiency (%) Main observed phenomena -0.3 50 60.0 ± 0.5 Reaction smooth, slight hydrogen evolution -0.4 80 70.2 ± 0.3 Butadiene production rate highest -0.5 120 65.5 ± 0.4 Hydrogen evolution side reaction enhanced Each set of conditions was tested three times, and the mean ± standard deviation was taken. The results showed that when the cathode potential was -0.4V vs. RHE, the current density could reach 80 mA / cm². 2When the time exceeds 100 hours, the butadiene Faradaic efficiency reaches a peak of 70.2%, and the side reactions are minimized, making it the optimal operating window for this process.

[0034] Example 3: Effect of Catalyst The catalyst of the cathode gas diffusion electrode was replaced with silver nanoparticles (deposited on carbon paper via reduction with AgNO3 solution, with a loading of 1.0 mg / cm³). 2 Other conditions are the same as in Example 1. At 80 mA / cm 2 The Faraday efficiency of butadiene was 55.3% and that of ethylene was 30.1% when tested at current density.

[0035] This example illustrates that different catalysts can adjust the product distribution, but copper-based catalysts are more advantageous for generating butadiene in this system.

[0036] Example 4: Long-term operation test Using the system configuration and process conditions of Example 1, a continuous stability test was conducted for 500 hours. During the test, the outlet gas of the cathode chamber was collected every 50 hours, and the product composition was analyzed using online gas chromatography, and the butadiene Faradaic efficiency was calculated. At the end of the test (500 hours), samples were taken from the cathode gas diffusion electrode, and the catalyst morphology was observed using a scanning electron microscope (SEM, model: Hitachi SU8020).

[0037] Test results: (1) Performance stability: During the entire 500-hour operation period, the system operated smoothly, and the Faradaic efficiency of butadiene remained within the range of 68% to 70.5%, without showing a continuous downward trend. The efficiency at the endpoint was 68.7%. (2) Catalyst durability: SEM characterization showed that the Cu(OH)₂ nanocatalyst maintained its initial nanosheet structure intact after 500 hours of reaction, with no obvious agglomeration, detachment, or dissolution observed. The average efficiency decay was calculated to be less than 5%. (3) Energy consumption and economy: The average energy consumption during the 500-hour test was 1.75 kWh / kg butadiene. Compared with the typical energy consumption of the traditional naphtha cracking by-product C4 fraction extraction method (2.5-2.9 kWh / kg), the energy consumption of this process is reduced by more than 30%.

[0038] Conclusion: This embodiment strongly demonstrates that the system and method described in this invention possess excellent long-term operational stability and catalyst durability, fully meeting the stringent requirements of industrial continuous production for equipment and process stability.

[0039] Example 5: Effect of alkaline electrolytes The system was the same as in Example 1, except that the electrolyte was replaced with a 1M NaOH aqueous solution, while other parameters remained unchanged. After the reaction stabilized, the butadiene Faraday efficiency was tested to be 67.5%, which was comparable to the effect achieved using the KOH solution.

[0040] This embodiment demonstrates that the system of the present invention is versatile for alkaline electrolytes.

[0041] Example 6: Scale-up Test The system described in Example 1 was scaled up 10 times (the effective area of ​​the cathode in the electrolytic cell was increased 10 times), the acetylene gas velocity was increased to 400 sccm, and the cathode current density was maintained at 80 mA / cm². 2 The system was operated continuously for 200 hours. Results showed that the butadiene yield stability was >92%, the average Faraday efficiency was >68%, and the energy consumption was 1.78 kWh / kg butadiene, confirming that the system of this invention has good scalability and industrial application prospects.

[0042] Example 7: Testing of different catalyst and electrolyte combinations The system is the same as in Example 1, and two sets of tests are performed: Test A: The catalyst of the cathode gas diffusion electrode was replaced with palladium nanoparticles (deposited on carbon paper via reduction with PdCl2 solution, loading 1.2 mg / cm³). 2 The cathode electrolyte was replaced with a 0.5M K₂CO₃ aqueous solution, while other parameters remained the same as in Example 1. The cathode current density was 80 mA / cm². 2 In the following tests, the Faradaic efficiency of butadiene was 58.5%, and the Faradaic efficiency of ethylene was 25.3%. Test B: Using the same Cu(OH)₂ nanocatalyst as in Example 1, the cathode electrolyte was replaced with a mixed alkaline electrolyte of 1M NaOH + 0.1M KCl, with other parameters remaining the same as in Example 1. The cathode current density was 80 mA / cm². 2 The test showed that the Faraday efficiency of butadiene was 66.8%.

[0043] This embodiment demonstrates that the system of the present invention has a certain degree of universality for catalyst and alkaline electrolyte systems, and the core system integration architecture is the key to achieving efficient and stable operation.

[0044] Comparative Example 1: Testing of an isolated electrolyzer, simulating the closest existing technology CN112342562A To demonstrate the inventiveness of this invention, the applicant, referring to the conditions of Example 1 of the closest prior art (Chinese Patent CN112342562A), constructed an isolated reaction unit containing only the gas diffusion electrode electrolyzer disclosed therein to conduct an acetylene electrocatalytic reduction experiment. This comparative example did not integrate the acetylene generating device described in this invention (instead, it used direct acetylene gas supply from a gas cylinder) and the product separation system (the reaction products were directly emitted rather than collected and separated). Specific conditions were as follows: the same Cu(OH)₂ nanocatalyst (loading 1.0 mg / cm³) as in Example 1 of this invention was used. 2 The cathode electrolyte is 1M KOH, and the cathode current density is controlled at 80 mA / cm². 2 Acetylene gas with a purity of 98% was introduced (flow rate 40 sccm).

[0045] Test results show that due to the lack of an integrated mechanism for stable feed gas supply and timely product removal, the reaction system pressure and gas phase composition are unstable, causing the acetylene conversion rate to begin to decline significantly after one hour of operation. The average butadiene Faradaic efficiency is approximately 55% after 5 hours of continuous operation. The reaction cannot be maintained for extended periods, let alone achieve continuous production.

[0046] This comparative result demonstrates that the present invention integrates the calcium carbide acetylene generator, the electrolyzer with a specific structure, and the product separation system into a single unit, rather than a simple superposition or conventional method in this field. This complete system integration brings unexpected technical effects—a qualitative leap from intermittent laboratory operation to continuous and stable industrial production, and significantly improves reaction efficiency (butadiene Faradaic efficiency increased from approximately 55% to over 68%) and long-term operational stability.

[0047] Comparative Example 2: Performance Testing of Simulated Traditional H-Type Electrolyzer To highlight the crucial role of the gas diffusion electrode (GDE) in this invention, a conventional H-type electrolytic cell was constructed for comparative experiments. This comparative example used the same Cu(OH)₂ nanocatalyst as in Example 1 of this invention, but coated it onto a standard planar carbon felt electrode (1cm × 1cm) as the cathode. The cathode and anode chambers were separated by an anion exchange membrane. The cathode electrolyte was 1M KOH, and acetylene gas (98% purity, flow rate 40 sccm) was continuously bubbled through to provide reactants. At a potential of -0.4V vs. RHE, the highest current density reached was only 30 mA / cm². 2 (Due to mass transfer limitations, it is impossible to increase to a higher level).

[0048] Test results: After 2 hours of stable operation, online gas chromatography analysis showed that the butadiene's Faradaic efficiency was only 42.1%. Meanwhile, due to the low solubility and slow mass transfer rate of acetylene in the liquid phase, the system current fluctuated significantly, making it impossible to stably maintain the target current density. After 5 hours of operation, the butadiene efficiency dropped below 35%.

[0049] Comparative Conclusion: This comparative example demonstrates that in conventional electrolytic cells without gas diffusion electrodes, even with the same active catalyst, severe mass transfer limitations lead to low reaction efficiency, inability to increase current density, and unstable operation. This conversely proves that the three-phase reaction interface constructed with gas diffusion electrodes, as described in this invention, is an indispensable key technical feature for achieving high current density, high selectivity, and stable operation.

[0050] Table 2 Comparison of Key Performance Data of Examples

[0051] Overall conclusion: The system of this invention operates at current densities of 10-150 mA / cm². 2 Within a cathode potential range of -0.2V to -0.6V (relative to the reversible hydrogen electrode), the butadiene Faraday efficiency is consistently above 68%, reaching a maximum of 70%, with energy consumption below 2.03 kWh / kg. The test results of Comparative Example 1 (incomplete system) and Comparative Example 2 (traditional H-type electrolyzer) highlight the superior performance of this invention from different perspectives: Comparative Example 1 demonstrates the necessity of complete system integration for continuous and stable operation; Comparative Example 2 demonstrates the crucial role of using a gas diffusion electrode to overcome mass transfer bottlenecks and achieve high current density and high efficiency. The data from the examples and thorough comparison with the comparative examples collectively confirm that this invention, through the creative integration and synergistic optimization of the "reaction-transfer-separation" system, solves the key technical problems of low acetylene mass transfer efficiency, poor reaction selectivity, and inability to achieve continuous and stable operation, realizing the efficient, stable, and continuous preparation of butadiene. Its comprehensive performance is significantly superior to the existing solutions mentioned in the background art. This fully demonstrates the non-obviousness and significant progressiveness of the technical solution of this invention.

[0052] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. 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 continuous production system for preparing butadiene by electrolysis of calcium carbide and acetylene, characterized in that: The device comprises an acetylene generator, an electrolytic cell, and a product separation system connected in sequence. The outlet of the acetylene generator is connected to the gas inlet of the cathode chamber of the electrolytic cell; the outlet of the cathode chamber of the electrolytic cell is connected to the inlet of the product separation system; the electrolytic cell includes a cathode chamber and an anode chamber separated by a diaphragm; a gas diffusion cathode electrode is disposed in the cathode chamber; and a nickel foam anode is disposed in the anode chamber, wherein the purity of the nickel foam anode is not less than 99.5% and the pore size is 300-800 μm.

2. The system according to claim 1, characterized in that: The catalyst of the gas diffusion anodizing electrode comprises one or more of copper, silver, and palladium, supported on a conductive substrate at a loading of 0.5-2.0 mg / cm³. 2 .

3. The system according to claim 1, characterized in that: The system also includes a cathode electrolyte preparation tank and an anode electrolyte preparation tank, which are connected to the cathode chamber and the anode chamber respectively via a circulating pump, with a circulation flow rate of 20-50 mL / min.

4. The system according to claim 1, characterized in that: The product separation system includes a gas-liquid separator and a distillation column for separating butadiene, hydrogen, ethylene and oxygen.

5. A method for preparing butadiene by electrolytic acetylene electrolysis from calcium carbide, characterized in that: Using the system as described in any one of claims 1-4, and including the following steps: S1. React calcium carbide and water in an acetylene generator to produce acetylene gas with a purity >98%. S2. The acetylene gas is continuously introduced into the cathode chamber of the electrolytic cell at a flow rate of 10-100 sccm, while the cathode potential of the cathode chamber is controlled to be -0.2V to -0.6V (relative to the reversible hydrogen electrode), so that the cathode current density is maintained at 80-150 mA / cm. 2 ; S3. The product output from the cathode chamber is sent into the separation system to obtain butadiene, hydrogen and ethylene; oxygen is output from the anode chamber.

6. The method according to claim 5, characterized in that: In step S2, both the cathode electrolyte and the anolyte are 0.1-5M KOH solutions, and the temperature is maintained at 20-40℃.

7. The method according to claim 5, characterized in that: In step S3, the butadiene Faraday efficiency is >68% and the hydrogen purity is >98%.

8. The method according to claim 5, characterized in that: The method also includes an online monitoring unit for real-time analysis of product composition and energy consumption.

9. The method according to claim 5, characterized in that: The cathode potential is -0.4V vs. RHE, the acetylene gas flow rate is 40 sccm, and the cathode current density is 80 mA / cm². 2 .

Images