Cylindrical flow reactor for electrosynthesis of biofuels via kolbe reaction

Abstract

A cylindrical flow reactor for electrosynthesis of biofuels via the Kolbe reaction and a use thereof. A single reactor unit consists of a central rod-shaped electrode and an outer tubular electrode, which are separated by electrically insulating supports located at two ends of the reactor, with no membrane between the electrodes. By regulating three pathways in the Kolbe reaction, i.e., disproportionation reaction, dimerization reaction, and Hofer‑Moest reaction, the membrane-free cylindrical continuous flow reactor electrocatalytically converts biomass-derived fatty acids into hydrocarbon (alkane / alkene), alcohol, and aldehyde biofuels, thereby reducing by-products of ester-based biodiesel, and costs are lowered because of the scalable cylindrical design of the flow reactor.

Description

Cylindrical flow reactor for electrosynthesis of biofuels using the Kolbe reaction Technical Field

[0001] This invention belongs to the field of biomass energy utilization, and more specifically, relates to a cylindrical flow reactor for the electrosynthesis of biofuels using the Kolbe reaction, specifically designed for converting bio-derived fatty acid molecules into biofuels using an electrocatalytic process. Background Technology

[0002] With dwindling fossil fuel supplies and increasingly severe environmental problems, biomass is considered a promising fuel source. Biomass possesses high energy reserves, is clean, and is renewable, making it a highly promising alternative energy source. Currently, the rapid pyrolysis of biomass to produce bio-oil, fuel gas, and biochar has become an effective way to utilize biomass resources. However, the direct application of bio-oil is limited due to its high viscosity, high water content, high oxygen content, corrosiveness, and chemical instability. Therefore, bio-oil should undergo hydrogenation and upgrading treatment before being used to produce liquid fuels.

[0003] Traditional hydrogenation and upgrading processes are carried out at high temperatures. However, bio-oils are prone to polymerization when heated. Due to their thermal instability at high temperatures, bio-oils can polymerize to form coke, which can clog the active sites of the catalyst and the reactor, affecting the stability of the upgrading process.

[0004] For electrosynthetic fuels, simple electrosynthetic reactors have been previously demonstrated. Most demonstrations have been conducted on a laboratory scale. Some of these reactors are "membrane-free," while others use membranes with proton exchange (proton exchange membrane, PEM) or hydroxide ion exchange (alkaline exchange membrane, AEM). Most commonly, these electrosynthetic reactors are used to produce hydrogen via water splitting, with oxygen as a byproduct. Large-scale industrial-scale water splitting electrolyzers have been demonstrated and commercialized. Recently, a technique for electrosynthesizing syngas (CO and H2) from CO2 and H2O has been demonstrated, with H2O as a byproduct. These demonstrations are generally limited to laboratory scale. Due to the importance of the electrode spacer membrane, membrane-free electrosynthetic reactors are rare, and currently there are no industrial-scale membrane-free reactors that can directly utilize electricity to hydrogenate and upgrade bio-derived molecules obtained from biomass. In terms of fuels, this means the production of alkanes, alkenes, alcohols, or similar compounds from raw biomass molecules. Here, biomass is defined as any plant or animal material that has recently extracted carbon from atmospheric CO2 (e.g., wood, agricultural waste and byproducts, food waste and byproducts, municipal solid waste, straw, potatoes, corn cobs, rice husks, etc.), rather than fossil carbon from petroleum products. However, previous studies have demonstrated electrocatalytically driven biomass conversion to increase the value of biomolecules on a laboratory scale.

[0005] It has been demonstrated that it is feasible to use electricity to convert bio-derived molecules in simple reactors. The molecules converted include vegetable oils, long-chain fatty acids, medium-chain fatty acids, and a variety of other less common molecules. Molecular value-added processes typically transform molecules into products suitable for use in industries other than energy (pharmaceuticals / healthcare, polymers / plastics, chemicals, etc.). In the energy sector, molecules are often deoxygenated and converted into alkanes, alkenes, alcohols, or similar compounds. While reports of directly converting biomolecules into alkane or olefin fuels are relatively limited, they have been demonstrated. Currently, there are no suitable industrial-scale systems for the electrosynthesis and conversion of bio-derived molecules into high-quality fuels.

[0006] There are three main forms of fuel that can be produced from fatty acids, one being biodiesel, another being hydrotreated vegetable oil (HVO), and the third being electrocatalytic fuel products produced using green electricity in an electrolyte solution. The most common method currently is to produce biodiesel using fatty acids and natural oils through a transesterification process. This process involves using an alkaline catalyst, typically sodium hydroxide and methanol, to convert triglyceride oil into ester chains, with glycerol as a byproduct. The final product is a fuel suitable for combustion in diesel engines; however, it retains oxygen in the ester functional groups, so its fuel properties are not entirely equivalent to conventional diesel because it is not fully deoxygenated. This is one of the only drawbacks of biodiesel fuel—its continued oxygen retention means it can be consumed by microorganisms, leading to spoilage, and may absorb moisture, limiting its functionality as a fuel. HVO undergoes hydrotreating to remove oxygen, resulting in a fuel very similar in composition and performance to fossil diesel, thus improving engine compatibility and efficiency. Electrocatalytic alkane fuels represent a new approach where energy promotes chemical reactions to synthesize alkanes from renewable feedstocks. This technology, including methods such as Kolbe electrosynthesis, uses renewable electricity to convert carboxylic acids into clean-burning hydrocarbons, providing a sustainable alternative to reduce greenhouse gas emissions.

[0007] Given the above, we designed a reactor for the electrocatalytic synthesis of low-carbon fuels from bio-derived fatty acid molecules under mild conditions, employing the Kolbe reaction for biofuel electrosynthesis. Kolbe electrosynthesis provides an innovative method for sustainable hydrocarbon production, converting carboxylic acids from biomass into valuable alkanes. The Kolbe process is an oxidation reaction of fatty acids. It produces CO2 from biomolecules at the oxidation electrode (cathode). The Kolbe process is known to have minimal electrochemical activity at the cathode. In fact, except at higher voltages (e.g., 4-10 V) and current densities (>50 mA / cm²), it exhibits minimal activity. 2Aside from producing a small amount of hydrogen, electrochemical activity is entirely suppressed at the cathode. Fatty acid molecules reacting via the Kolbe process interact only with the oxidation electrode (anode), not the cathode. Water in the electrolyte solution is the only substance that interacts with the reduction electrode (cathode). Due to this unique electrochemistry of the Kolbe process, the suppression of reactions involving biomolecules at the cathode eliminates the need for a semi-permeable membrane for product isolation. The fact that fatty acids react only with the anode allows the reactor to operate efficiently without a membrane. This membrane-free electrochemical technology offers two additional advantages. Membrane removal increases the reactor's ionic conductivity, thereby improving reactor efficiency. Membranes are also among the most maintenance-intensive components in electrocatalytic reactors. Therefore, eliminating the need for membranes reduces maintenance costs. Membranes can be very expensive, costing similar to or higher than catalyst coatings in the reactor. Furthermore, this electrochemical process, driven by renewable electricity, significantly reduces reliance on fossil fuels and hazardous chemicals, making it an environmentally friendly option. Its high selectivity, efficiency, and controllability facilitate the precise synthesis of target hydrocarbons, ensuring fewer byproducts and increased yields. This technology is scalable for industrial applications, suitable for a wide range of fuel and chemical production, while reducing greenhouse gas emissions. Furthermore, by using renewable feedstocks and simplifying the synthesis process, electrosynthesis can reduce production costs, creating a more economical and sustainable future for the fuel industry. Its adaptability in producing a variety of hydrocarbons meets numerous market demands, making it a key technology for promoting green energy alternatives. Summary of the Invention

[0008] To address the aforementioned deficiencies or improvement needs of existing technologies, the present invention aims to provide a cylindrical flow reactor for the electrosynthesis of biofuels via the Kolbe reaction. The reactor design of this invention solves the problems of inaccurate product control in the electrosynthesis process, including the inability to precisely control the synthesis of target hydrocarbons, complex equipment structure, high cost, poor product selectivity, low yield, and numerous byproducts.

[0009] The present invention provides a cylindrical flow reactor for electrosynthesizing biofuels using the Kolbe reaction, comprising an inner electrode rod at the center, a cylindrical outer shell electrode, and support members at both ends of the reactor along the axial direction. The support members are made of electrically insulating material, and there is no electrode spacer membrane inside the reactor.

[0010] Furthermore, the support member is divided into a top support member and a bottom support member. The outer shell electrode is a hollow cylindrical structure made of stainless steel. The inner electrode rod is supported by the top and bottom support members and is connected to the inner electrode contact point through the top support member. The electrolyte inlet is located in the top support member, and the electrolyte outlet is located in the bottom support member. The outer shell electrode contact point is located on the top support member and is connected to the outer shell electrode through the top support member.

[0011] Furthermore, the inner electrode rod passes through the inner cavity formed by the outer shell electrode, the radial width of which is 1 to 20 millimeters.

[0012] Furthermore, the electrolyte enters the chamber in the top support through the electrolyte inlet, and then flows into the narrow inner cavity, where it reacts with the current between the inner and outer electrodes. The product molecules then enter the chamber in the bottom support and flow out through the electrolyte outlet.

[0013] Furthermore, the selection of the positive and negative electrodes connected to the inner electrode rod and the outer shell electrode is relatively flexible, mainly determined by the processing morphology and ease of the electrocatalyst. The inner layer of the outer shell electrode is generally a metal or metal oxide coating acting as a catalyst, such as an electroplated platinum metal layer (catalyst selections include: platinum (Pt), ruthenium (Ru), nickel (Ni), cobalt (Co), iron (Fe), chromium (Cr), palladium (Pd), and iridium (Ir)), or a nanoparticle-supported electrode (e.g., small particles of Pt, Ru, Ni, Co, Fe, Cr, Pd, and Ir are usually coated on a conductive material or "substrate"). The inner electrode rod material can be stainless steel rod, mild steel rod, graphite rod, lead rod, metal oxide electrode rod (e.g., iron hydroxide and nickel-doped compounds), or a dimensionally stable anode (DSA) rod (e.g., titanium-based ruthenium dioxide DSA), etc.

[0014] Furthermore, both the cathode and anode catalysts are selected to be platinum-coated.

[0015] Furthermore, electrolytes are generally used in industrial-scale alkaline solutions, which typically contain sodium hydroxide (NaOH) or potassium hydroxide (KOH).

[0016] Furthermore, the electrolyte solution is selected as a mixed solution composed of sodium hydroxide (NaOH) and / or potassium hydroxide (KOH) with fatty acids, and the pH value of the electrolyte solution is between 8 and 13 before the electrochemical reaction is carried out.

[0017] Furthermore, the portions of the top support and the bottom support that contact the outer casing electrode are provided with annular sealing rings, and the top support and the bottom support are connected to the outer casing electrode by screwing in bolts.

[0018] Compared to current technologies, the cylindrical design allows for the manufacture of low-cost reactors using readily available parts, whereas existing technologies require high-precision machining, limiting the scalability of known and disclosed existing reactors. This cylindrical approach preserves desirable design parameters such as high precision electrode spacing, simple application of catalyst coatings, precise control of flow rates, and the advantage of the current density ratio between the inner and outer electrodes.

[0019] Furthermore, this invention provides a central reactor (reactor) composed of a set of central cylindrical reactor units. The aforementioned cylindrical flow reactors are used as cylindrical reactor units to form a reactor-stacking type central reactor. An electrolyte solution containing reactant molecules and fuel products flows parallel through each cylindrical reactor unit. The reactor is cooled and maintained at a constant temperature using an external cooling device or "cooler." The coolant (which does not cause leakage after the reactor is energized) is guided to flow over the outer surface of each cylindrical reactor. The reactant molecules are mixed with the electrolyte solution in an external container and pumped into the reactor using an electrolyte peristaltic pump (e.g., a high-performance liquid chromatography (HPLC) pump) that does not corrode under alkaline conditions. After passing through the reactor, most molecules are decarboxylated, forming alkanes and alkenes, and are easily separated from the electrolyte solution. The applied reaction conditions are a voltage range of 2–12 V and a current density of 50 mA / cm². 2 ~1.5A / cm 2 The two electrodes are spaced 2 cm apart, and the electrolyte is a mixture of fatty acids and sodium hydroxide. The electrolyte solution temperature is 35-50 degrees Celsius, and the pH is 12-13. The central reactor achieves three pathway conversions—disproportionation, dimerization condensation, and Hof-Morst reaction—by adjusting the reaction parameters in the Kolbe, thereby electrocatalytically converting bio-derived fatty acids into hydrocarbon, alcohol, or aldehyde biofuels.

[0020] Raw materials are skimmed off during the initial coarse separation process and then purified to fuel quality through separate thermal treatments (e.g., fractionation) and centrifugation. In further processes, waste products such as alcohols and esters are also separated and purified for sale as value-added products, again using thermal treatment processes such as fractionation and centrifugation. Product molecules that cannot be sold as fuel are disposed of, and value-added products are collected and sold. The electrolyte liquid, mainly composed of water and alkali (e.g., NaOH, KOH), is recycled back to the initial container, mixed with new reactant molecules, and the fuel production cycle continues.

[0021] This invention improves the structure and component arrangement of such reactors by simplifying these components, increasing process scalability. Compared to existing technologies, this invention primarily addresses the cost issue. It allows for the fabrication of high-performance electrochemical reactors from simple, mass-producible rods and tubes, enabling the synthesis of biofuels using electricity. The reactor also easily handles increased pressure by using a relatively thick outer wall on the electrocatalytic tubes.

[0022] This reactor achieves a unique "quasi-separated" continuous flow system. This allows for significant differences in current density between the two electrodes, resulting in substantial variations in the net products that the reactor may produce, especially when the applied voltage and current directions are reversed. When a decline in the catalytic performance of a single reactor unit is observed after a period of time, it can be easily replaced from the overall reactor for maintenance or recycling. The manufacturing process is simple and suitable for large-scale production, enabling the mass production of low-carbon biofuels. Attached Figure Description

[0023] Figure 1 is a block flowchart of the entire reactor system.

[0024] Figure 2 shows a more detailed view of the equipment and electrolyte flow throughout the reactor system.

[0025] Figure 3 shows an external view of a single reactor.

[0026] Figure 4 is an exploded view of a single reactor.

[0027] Figure 5 shows the structure of the central inner electrode rod and the cylindrical tubular outer shell electrode of the reactor.

[0028] Figure 6 shows the front and rear support components of the reactor: a) left view, b) right view.

[0029] Figure 7 is a cross-sectional view of a single reactor.

[0030] Figure 8 shows a side view of a single reactor: a) right view, b) right view electrical connection diagram.

[0031] Figure 9 shows a cross-sectional side view of the front and rear connectors of the reactor: a) right view, b) left view.

[0032] Figure 10 shows the reaction product results using decanoic acid as a raw material: a) reaction process diagram, b) gas chromatography-mass spectrometry (GC-MS) spectrum showing detection of octadecane; c) nuclear magnetic resonance (NMR) spectrum showing detection of octadecane.

[0033] Figure 11 is a schematic diagram of the reaction products of the Hof-Morst reaction pathway using decanoic acid as a raw material: a) Gas chromatography-mass spectrometry (GC-MS) chromatogram of nonanal detected; b) Gas chromatography-mass spectrometry (GC-MS) chromatogram of nonanol detected.

[0034] Reference numerals: 1. Outer electrode, 2. Inner electrode rod, 3. Electrolyte inlet, 4. Electrolyte outlet, 5. Top support, 6. Bottom support, 7. Inner electrode connection point, 8. Outer electrode connection point, 9. Inner cavity. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0036] Figure 1 shows a slightly simplified flowchart of a complete reactor system. An organic electrolyte mixer mixes feedstock molecules (such as fatty acids, oils, tallow) with water and an alkali (such as sodium hydroxide), as well as any additional salts or solvents (such as ethanol); this mixture is defined as the electrolyte solution. A reaction pump delivers the electrolyte solution from the organic electrolyte mixer to cylindrical Kolbe reactor elements at a constant flow rate. Many cylindrical reactors are arranged in parallel to increase the total fuel yield. In the cylindrical reactors, after the feedstock has reacted to produce fuel, a preliminary fuel-electrolyte separation process first occurs through scraping and centrifugation. The generated fuel molecules are more hydrophobic than the feedstock molecules and therefore separate into an organic fuel layer, typically located above the aqueous electrolyte layer. This fuel layer can be separated by centrifugation and scraped off from the aqueous electrolyte. This coarse purification process leads to two further steps: fuel purification and electrolyte recovery. Subsequent fuel purification involves thermal treatment processes, such as fractionation or cooling, to separate long-chain hydrocarbons from short-chain hydrocarbons. Electrolyte recovery involves returning alkalis (such as sodium hydroxide), salts, and solvents to the organic electrolyte mixer, where new feedstock is added to repeat the fuel production cycle. Waste separation and treatment processes separate any value-added molecules (such as esters) from the crudely hydrolyzed molecules, which are then sent for further processing. Any molecules with additional value can also be collected and sold. After fine purification, the fuel is tested and certified before being sold on the market. A cooler (reactor temperature control system) circulates cooling water through a network of parallel reactor units to maintain a uniform temperature at the reactor core.

[0037] Figure 2 shows a flowchart similar to Figure 1, with added details. The reactant distribution manifold illustrates how the fuel is distributed to the individual cylindrical reactor units. A square chamber is used to collect overflowing gas via a one-way liquid valve. The generated fuel molecules exit from this reactor chamber and are transported to subsequent processes such as fuel-electrolyte separation and purification. Details of the cooling water flow are also shown, along with the intended orientation of the reactor units.

[0038] Figure 3 shows an external view of the assembled complete reactor. The outer electrode 1 is a simple tubular structure made of stainless steel. The inner electrode rod 2 is connected to its inner electrode contact 7 and is supported by the top support 5. The electrolyte inlet 3 is located in the top support 5, and the electrolyte outlet 4 is located in the bottom support 6. The outer electrode contact 8 is the electrical connection point of the outer electrode 1.

[0039] Figure 4 shows a cross-sectional view of the cylindrical reactor. The inner electrode rod 2 enters the inner cavity 9 formed by the outer shell electrode 1. The radial width of the inner cavity 9 formed by the inner electrode rod 2 and the outer shell electrode 1 is 1 to 20 mm.

[0040] Figure 5 shows only the inner electrode rod 2 and the outer shell electrode 1. It shows the relative length and distance of the inner electrode rod 2 inserted into the outer shell electrode 1.

[0041] Figure 6 shows the electrically insulating top support 5 and bottom support 6. These covers contain an electrolyte inlet 3 and an electrolyte outlet 4, respectively.

[0042] Figure 7 shows a cross-sectional view of the entire cylindrical reactor and illustrates the flow direction of the electrolyte through the reactor (green arrows). The electrolyte enters the chamber in the top support 5 through the electrolyte inlet 3, and then flows into the narrow inner cavity 9, where it reacts with the current between the inner electrode rod 2 and the outer shell electrode 1. The product molecules then exit the cylindrical reactor through the electrolyte outlet 4 located in the bottom support 6.

[0043] Figure 8 shows a cross-sectional perspective view of the entire cylindrical reactor in Figure 7, as well as a cross-sectional perspective view of the entire reactor without the top support 5. The electrical connection between the external power supply and the reactor unit is also shown. The external power supply is connected to the inner electrode contact 7, and further connected to the inner electrode rod 2. The external power supply is also connected to the outer shell electrode contact 8, which is connected to bolts via the top support 5, the bolts being screwed into the outer shell electrode 1.

[0044] Figure 9 shows a cross-sectional view of the top support 5 and the bottom support 6. The cross-sectional view shows the position of the annular sealing rings in the top support 5 and the bottom support 6.

[0045] Figure 10-11 illustrates the evidence for fatty acid conversion via the basic Kolbe process. The Kolbe reaction in actual production uses a voltage range of 2–12 V and a current density of 50 mA / cm². 2 ~1.5A / cm 2 This example demonstrates the master reaction under default settings: a cathode and anode using planar platinum electrodes, with a 2cm distance between the electrodes; an electrolyte mixture of decanoic acid and sodium hydroxide (containing decanoic acid, a fatty acid); an electrolyte solution at 35-50°C and pH 12-13; a voltage of 3.2V; and a current density of 190mA / cm². 2 Under these conditions, the reaction proceeds along the dimerization condensation pathway; voltage 5V, current density 200mA / cm². 2 The reaction is in the disproportionation pathway, voltage 10V, current density 1A / cm². 2 The reaction occurs along the Hof-Moist reaction pathway; specifically, in the dimerization condensation reaction, a 10-carbon fatty acid-decanoic acid containing a carboxylic acid functional group reacts at a platinum electrode to produce the alkane fuel product octadecane. Octadecane is a major component of conventional fossil diesel and jet fuel in the aviation industry. The composition of the product was confirmed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR). These two advanced characterization techniques are cutting-edge methods for the identification and quantification of organic compounds, clearly showing that the major product is a dimer fuel product—octadecane—formed by the combination of two decanoic acid molecules. By changing the voltage and current density, the main reaction pathway can be adjusted to a disproportionation reaction, thereby forming nonene and nonane; by further increasing the voltage and current density, the main reaction pathway can be adjusted to a Hof-Moist reaction, thereby forming nonanal and nonanol.

[0046] Table 1 shows the detailed proportions of each reaction product in the Hof-Morst reaction pathway, as follows:

[0047] The reactor design in this embodiment improves the structure and component arrangement of such reactors by simplifying components, increasing process scalability. This embodiment addresses cost issues, allowing for the fabrication of high-performance electrochemical reactors from simple, mass-producible rods and tubes for the electrosynthesis of biofuels. The reactor design allows for significantly different current densities between the two electrodes, resulting in substantial changes in the net product that the reactor may produce, especially when the applied voltage and current directions are reversed. When a decline in the catalytic performance of a single reactor unit is observed after a period of time, it can be easily replaced from the overall reactor for maintenance or recycling. The manufacturing process is simple and suitable for large-scale production, enabling the mass production of low-carbon biofuels. The embodiment also easily handles increased pressure by using a relatively thick outer wall on the electrocatalytic tube.

[0048] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and such modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A cylindrical flow reactor for the electrosynthesis of biofuels using the Kolbe reaction, characterized in that, It includes an inner electrode rod located at the center, a cylindrical outer shell electrode, and support members located at both ends of the reactor along the axial direction. The support members are made of electrically insulating material, and there is no electrode spacer membrane inside the reactor.

2. The cylindrical flow reactor according to claim 1, characterized in that, The support is divided into a top support and a bottom support; the inner electrode rod is supported by the top support and the bottom support, and is connected to the inner electrode contact point through the top support; the outer shell electrode contact point is located on the top support and is connected to the outer shell electrode through the top support.

3. The cylindrical flow reactor of claim 2, wherein, The electrolyte inlet is located in the top support, and the electrolyte outlet is located in the bottom support. The outer shell electrode is a hollow cylindrical structure made of stainless steel. The inner electrode rod is selected from stainless steel rod, mild steel rod, graphite rod, lead rod, metal oxide electrode rod, or shape-stable anode rod.

4. The cylindrical flow reactor according to any one of claims 1-3, characterized in that, The inner electrode rod passes through the inner cavity formed by the outer shell electrode, and the radial width of the inner cavity is 1 to 20 mm.

5. The cylindrical flow reactor according to claim 1, characterized in that, The electrolyte enters the chamber in the top support through the electrolyte inlet, and then flows into the narrow inner cavity. In this channel, a reaction occurs through the current between the inner and outer electrodes. The product molecules then enter the chamber in the bottom support and flow out through the electrolyte outlet.

6. The cylindrical flow reactor according to claim 5, characterized in that, The surface of the inner electrode rod and the inner surface of the outer electrode are both coated with a platinum metal catalyst. The electrolyte solution is selected as a mixed solution composed of sodium hydroxide and / or potassium hydroxide and fatty acids. The pH value of the electrolyte solution is between 8 and 13 before the electrochemical reaction.

7. The cylindrical flow reactor according to claim 1, characterized in that, The portions of the top support and the bottom support that contact the outer casing electrode are provided with annular sealing rings, and the top support and the bottom support are connected to the outer casing electrode by screwing in bolts.

8. An application of a cylindrical flow reactor for the electrosynthesis of biofuels via the Kolbe reaction, characterized in that, The cylindrical flow reactor described herein is the cylindrical flow reactor for electrosynthesizing biofuels using the Kolbe reaction as described in any one of claims 1-7. The feedstock is biomass-derived fatty acid molecules. During the reaction, the cylindrical flow reactor operates at a voltage range of 2–12 V and a current density of 50 mA / cm². 2 ~1.5A / cm 2 The distance between the two electrodes is 2 cm. The electrolyte is a mixture of fatty acids and sodium hydroxide. The temperature of the electrolyte solution is 35-50 degrees Celsius and the pH is 12-13.

9. A cylindrical reactor unit constituting a central reactor, characterized in that, The cylindrical flow reactor according to any one of claims 1-7 is used as the central reactor of the reactor stack, which is composed of cylindrical reactor units. An electrolyte solution containing reactant molecules and fuel products flows in parallel through each of the cylindrical reactor units. The reactor is cooled and kept at a constant temperature by an external cooling device. The coolant is guided to flow over the outer surface of each of the cylindrical reactors. The reactant molecules and electrolyte solution are mixed in an external container and pumped into the reactor using an electrolyte peristaltic pump that does not corrode under alkaline conditions. After passing through the reactor, most of the molecules are decarboxylated to form alkanes and alkenes.

10. The central reactor of claim 9, wherein, The central reactor achieves three pathway conversions—disproportionation, dimerization condensation, and Hof-Morst reaction—by regulating the reaction parameters in the Kolbe, thereby electrocatalytically converting bio-derived fatty acids into hydrocarbon, alcohol, or aldehyde biofuels.

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