Cylindrical flow reactor for electrosynthesis of biofuels using the Kolbe reaction

Abstract

The present invention relates to a cylindrical flow reactor for electrosynthesizing biofuels using the Kolbe reaction. A single reactor unit consists of a central rod electrode and an outer tube electrode, which are separated by electrical insulating supports located at both ends of the reactor. The reactor is characterized in that there is no diaphragm between the electrodes. The membraneless cylindrical continuous flow reactor converts bio-derived fatty acids into hydrocarbon (alkane / alkene) alcohol and aldehyde biofuels by regulating three pathways of Kolbe disproportionation, dimerization and Hofer-Moest reactions, thereby minimizing the byproducts of ester biodiesel and reducing costs due to its scalable cylindrical design.

Description

Technical Field

[0001] The invention belongs to the field of biomass energy utilization, and more specifically, relates to a cylindrical flow reactor for electrosynthesizing biofuels by Kolbe reaction, which is specially used for converting bio-derived fatty acid molecules into biofuels by using an electrocatalytic process. Background Art

[0002] With the reduction of fossil fuel supply and the increasing environmental problems, biomass is considered to be a promising fuel source. Biomass has high energy reserves, cleanliness and renewability, and is a highly promising alternative energy source. At present, the use of biomass rapid pyrolysis to produce bio-oil, gas, biochar, etc. has become an effective way to utilize biomass resources. However, due to the high viscosity, high water content, high oxygen content, corrosiveness and chemical instability of bio-oil, its direct application is limited. Therefore, bio-oil should be hydrogenated and upgraded before being used to produce liquid fuels.

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

[0004] For electrosynthesized fuels, simple electrosynthesis reactors have been demonstrated before. Most demonstrations were performed at laboratory scale. Some of these reactors are “membraneless” or use membranes that exchange protons (proton exchange membrane, PEM) or hydroxide ions (alkaline exchange membrane, AEM). Most commonly, these electrosynthesis reactors are used to produce hydrogen via a water splitting reaction with oxygen as a byproduct. Large industrial-scale water splitting electrolyzers have been demonstrated and commercialized. More recently, electrosynthesis of syngas (CO and H2) from CO2 and H2O has been demonstrated with H2O as a byproduct. These demonstrations are usually limited to laboratory scale. Due to the importance of the membrane separating the electrodes, membraneless electrosynthesis reactors are rare, and there are currently no industrial-scale membraneless reactors that can directly use electricity to hydrogenate and upgrade biologically derived molecules obtained from biomass. In terms of fuels, this means the production of alkanes, alkenes, alcohols or similar from the original molecules of biomass. Here, biomass is defined as any plant or animal matter that has recently derived its 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, electrocatalytically driven biomass conversion to add value to biomolecules has been demonstrated on a laboratory scale in previous studies.

[0005] It has been demonstrated that it is feasible to transform bioderived molecules in simple reactors using electricity. The molecules transformed include vegetable oils, long-chain fatty acids, medium-chain fatty acids, and a variety of other less common molecules. Molecular valorization typically transforms molecules into products suitable for use in industries other than energy (pharmaceuticals / healthcare, polymers / plastics, chemicals, etc.). In energy, molecules are typically deoxygenated and converted to alkanes, alkenes, alcohols, or the like. Direct conversion of biomolecules to alkane or alkene fuels has been demonstrated, although reports are relatively limited. Currently, there are no industrial-scale systems suitable for the electrosynthesis and conversion of bioderived molecules into high-quality fuels.

[0006] There are three main forms of fuel that can be produced from fatty acids, one of which is biodiesel, another is hydrotreated vegetable oil (HVO), and the third is an electrocatalytic fuel product produced in an electrolyte solution using green electricity. The most common method currently uses fatty acids and natural oils to produce biodiesel through a transesterification process. The process involves the use of an alkaline catalyst, usually sodium hydroxide and methanol, to convert triglyceride oil into ester chains, with glycerol as a byproduct. The final product is a fuel suitable for burning in a diesel engine, however it retains oxygen in the ester functional groups, so its fuel properties are not completely equivalent to traditional diesel because it is not fully deoxygenated. This is one of the only disadvantages of biodiesel fuel, that it continues to retain oxygen, which means it can be consumed by microorganisms, causing deterioration, and may absorb water, limiting its functionality as a fuel. HVO is hydrotreated to exclude oxygen, resulting in a fuel that is very similar to fossil diesel in composition and properties, thereby improving engine compatibility and efficiency. Electrocatalytic alkane fuels embody a new approach in which energy sources promote chemical reactions to synthesize alkanes from renewable feedstocks. The technology, which includes methods such as Kolbe electrosynthesis, uses renewable electricity to convert carboxylic acids into clean-burning hydrocarbons, offering a sustainable alternative for reducing greenhouse gas emissions.

[0007] In view of the above, we designed a reactor for electrocatalytic synthesis of low-carbon fuels from bio-derived fatty acid molecules under mild conditions, which adopts the Kolbe reaction to electrosynthesize biofuels. Kolbe electrosynthesis provides an innovative approach for sustainable hydrocarbon production, which converts 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 process activity at the cathode. In fact, except for large voltages (e.g. 4-10 V) and current densities (>50mA / cm 2) and the electrochemical activity is suppressed overall at the cathode. The fatty acid molecules reacting through 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, the electrochemical reaction system no longer requires a semipermeable membrane for product isolation. The fact that the fatty acids react only with the anode allows the reactor to operate efficiently without a membrane. This membraneless electrochemical technology has two additional advantages. The removal of the membrane increases the ionic conductivity of the reactor, thereby improving the efficiency of the reactor. The membrane is also one of the components in the electrocatalytic reactor that requires a lot of maintenance. Therefore, eliminating the need for a membrane reduces maintenance costs. Membranes can be very expensive, with costs similar to or higher than the catalyst coating in the reactor. In addition, this electrochemical process driven by renewable electricity significantly reduces dependence on fossil fuels and hazardous chemicals, making it an environmentally friendly option. Its high selectivity, high efficiency, and controllability help to precisely synthesize target hydrocarbons, ensuring fewer byproducts and increased yields. The technology is scalable for industrial applications and is suitable for a wide range of fuel and chemical production while reducing greenhouse gas emissions. In addition, 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 many market needs, making it a key technology to promote green energy substitution. Summary of the invention

[0008] In view of the above defects or improvement needs of the prior art, the purpose of the present invention is to provide a cylindrical flow reactor for electrosynthesis of biofuels by Kolbe reaction. The reactor design of the present invention solves the problems that the products in the electrosynthesis process cannot accurately control the synthesis of target hydrocarbons, the equipment structure is complex, the cost is high, the product selectivity is poor, the yield is low, and there are many by-products.

[0009] The present invention provides a cylindrical flow reactor for electrosynthesizing biofuels using the Kolbe reaction, which includes an inner electrode rod located in the center, a cylindrical outer shell electrode, and support members located at both axial ends of the reactor, wherein the support members are made of an electrically insulating material, and there is no electrode spacing 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 support member and the bottom support member, and is connected to the inner electrode power connection 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 power connection is arranged 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 an inner cavity formed by the outer shell electrode, and the radial width of the inner cavity is 1 to 20 mm.

[0012] Furthermore, the electrolyte enters the chamber in the top support member through the electrolyte inlet, and then flows into the narrow inner cavity, where a reaction occurs through the current between the inner electrode and the outer electrode, and the product molecules then enter the chamber in the bottom support member and flow out from 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 form and difficulty of the electrocatalyst. The inner layer of the shell of the outer shell electrode is generally a metal or metal oxide coating that acts as a catalyst, such as an electroplated platinum metal layer (catalyst selections such as: platinum (Pt), ruthenium (Ru), nickel (Ni), cobalt (Co), iron (Fe), chromium (Cr), palladium (Pd) and iridium (Ir)), nanoparticle-loaded electrodes (for example: 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 a stainless steel rod, a mild steel rod, a graphite rod, a lead rod, a metal oxide electrode rod (such as iron hydroxide and a nickel-doped compound) or a dimensional stable anode DSA (Dimensional Stable Anode) rod (such as titanium-based ruthenium dioxide DSA) and other materials.

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

[0015] Furthermore, the electrolyte is generally an alkaline solution on an industrial scale, and the alkaline solution usually contains sodium hydroxide (NaOH) or potassium hydroxide (KOH).

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

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

[0018] The cylindrical design allows for the use of off-the-shelf parts to fabricate a low-cost reactor compared to current technologies, which require high-precision machining, limiting the scalability of existing reactors known and disclosed. This cylindrical approach retains desirable design parameters such as high precision of electrode spacing, simple application of catalyst coatings, precise control of flow rates, and an advantage in the current density ratio between the inner and outer electrodes.

[0019] Furthermore, the present invention provides a group of central cylindrical reactor units to constitute a central reactor (reactor stack), and the aforementioned cylindrical flow reactor is used as a cylindrical reactor unit to form a central reactor of a reactor stack type, and an electrolyte solution containing reactant molecules and fuel products flows through each cylindrical reactor unit in parallel. The reactor is cooled and maintained at a constant temperature using an external cooling device or "cooler", and the coolant (here the coolant does not cause leakage after the reactor is powered on) is guided to flow through 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 (such as a high-performance liquid chromatography (HPLC) pump) that does not corrode under alkaline conditions. After passing through the reactor, most of the molecules are decarboxylated to form alkanes and alkenes, and are easily separated from the electrolyte solution. The reaction conditions used are a voltage range of 2 to 12V and a current density of 50mA / cm 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 electrolyte solution temperature is 35-50 degrees Celsius, and the pH is 12-13. The central reactor realizes three pathway conversions of disproportionation reaction, dimerization condensation reaction and Hof-Möster reaction by regulating the reaction parameters in Kolbe, and electrocatalytically converts bio-derived fatty acids into hydrocarbons, alcohols or aldehydes biofuels.

[0020] The raw products are skimmed off during the initial crude separation and subsequently purified to fuel quality by separate thermal treatments (e.g. fractionation) and centrifugation. In further processes, waste products such as alcohols and esters are also separated and purified and sold as value-added products, also using thermal treatment processes such as fractionation and centrifugation. Product molecules that cannot be sold as fuel are disposed of and the value-added products are collected and sold. The electrolyte liquid, which mainly consists of water and alkali (e.g. NaOH, KOH), is recycled to the original container and mixed with new reactant molecules to continue the cycle of producing fuel.

[0021] The present invention improves the structure of such reactors and the arrangement of components by simplifying these components, increasing the scalability of the process. Compared with the prior art, the present invention mainly solves the cost problem. It allows simple, mass-produced rods and tubes to be made into high-performance electrochemical reactors for synthesizing biofuels using electricity. The reactor also simply handles increased pressure by using relatively thick outer walls on the electrocatalytic tubes.

[0022] The reactor implements a "quasi-separated" continuous flow system, which is highly unique. This allows the current density between the two electrodes to be significantly different, resulting in substantial changes in the net products that the reactor may produce, especially when the applied voltage and current direction are reversed. When the catalytic performance of an individual reactor unit is observed to decline after a period of time, it can simply be replaced from the overall reactor for maintenance or recycling. The manufacturing process is simple and suitable for large-scale production, thereby enabling large-scale production of low-carbon biofuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a block flow chart of the entire reactor system.

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

[0025] Figure 3 External view of a single reactor.

[0026] Figure 4 Exploded view of a single reactor.

[0027] Figure 5 The reactor has a central inner electrode rod and a cylindrical outer shell electrode structure.

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

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

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

[0031] Fig. 9 The sectional side view of the front and rear connectors of the reactor: a) right view, b) left view.

[0032] FIG10 is a schematic diagram of the reaction product results using decanoic acid as the raw material: a) reaction process diagram, b) gas chromatography-mass spectrometry (GC-MS) diagram of octadecane detected; c) nuclear magnetic resonance (NMR) diagram of octadecane detected.

[0033] Fig.11 Schematic diagram of the results of the Hof-Mörster reaction pathway reaction products using decanoic acid as the raw material: a) Gas chromatography-mass spectrometry (GC-MS) graph in which nonanal was detected; b) Gas chromatography-mass spectrometry (GC-MS) graph in which nonanol was detected.

[0034] Reference numerals:

[0035] 1. Outer shell electrode, 2. Inner electrode rod, 3. Electrolyte inlet, 4. Electrolyte outlet, 5. Top support, 6. Bottom support, 7. Inner electrode connection point, 8. Outer shell electrode connection point, 9. Inner cavity. DETAILED DESCRIPTION

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0037] Figure 1A slightly simplified flow diagram of the complete reactor system is shown. The organic electrolyte mixer mixes the feedstock molecules (e.g. fatty acids, oils, tallow) with water and a base (e.g. sodium hydroxide) and any additional salts or solvents (e.g. ethanol), and this mixture is defined as the electrolyte solution. A reaction pump delivers the electrolyte solution from the organic electrolyte mixer to the cylindrical Kolbe reactor element at a fixed flow rate. A number of cylindrical reactors are arranged in parallel to increase the total fuel production. After the feedstock reacts to form the fuel in the cylindrical reactor, a preliminary fuel-electrolyte separation process is first performed by scraping and centrifugation. The resulting fuel molecules are more hydrophobic than the feedstock molecules and therefore separate into an organic fuel layer that is usually located above the aqueous electrolyte layer. This fuel layer can be separated by centrifugation and scraped from the aqueous electrolyte. This crude purification process leads to two further steps, fuel purification and electrolyte recovery. Subsequent fuel purification uses thermal treatment steps such as fractionation or cooling to separate long-chain hydrocarbons from short-chain hydrocarbons. Electrolyte recovery recycles alkali (such as sodium hydroxide), salts and solvents back into the organic electrolyte mixer, where new feedstock is added to repeat the fuel production cycle. Waste separation and treatment processes separate any molecules with added value (such as esters) from the crude hydrolyzed molecules, which are sent for processing. Any molecules with additional value can also be collected and sold. After fine purification, the fuel is tested and certified before it is released to the market. A chiller (reactor temperature control system) circulates cooling water through a network of reactor units arranged in parallel to maintain a uniform temperature in the reactor core.

[0038] Figure 2 Shows the Figure 1 A similar flow chart with some added details. The reactant distribution manifold shows how the fuel is distributed to the various cylindrical reactor units. A square chamber is used to collect the escaping gas through a one-way liquid valve. The generated fuel molecules are discharged from this reactor chamber and sent to subsequent processes such as fuel-electrolyte separation and purification. The details of the cooling water flow are also shown, showing the expected arrangement of the reactor units.

[0039] Figure 3 An external view of the complete assembled reactor is shown. The outer shell electrode 1 is a simple tubular structure made of stainless steel. The inner electrode rod 2 is connected to its inner electrode connection 7 and 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 shell electrode connection 8 is the electrical connection point of the outer shell electrode 1.

[0040] Figure 4 A cross-sectional view of a cylindrical reactor is shown. 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.

[0041] Figure 5 Only the inner electrode rod 2 and the outer shell electrode 1 are shown. The relative length and distance of the inner electrode rod 2 inserted into the outer shell electrode 1 are shown.

[0042] Figure 6 An electrically insulating top support 5 and bottom support 6 are shown. The covers contain an electrolyte inlet 3 and electrolyte outlet 4, respectively.

[0043] Figure 7 A cross-section of the entire cylindrical reactor is shown, showing the direction of electrolyte flow 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 the reaction occurs through the current between the inner electrode rod 2 and the outer shell electrode 1. The product molecules then leave the cylindrical reactor through the electrolyte outlet 4 located in the bottom support 6.

[0044] Figure 8 Shown Figure 7 5 and a cross-sectional perspective view of the entire cylindrical reactor without the top support 5. The electrical connections of the external power supply to the reactor unit are also shown. The external power supply is connected to the inner electrode power connection 7 and in turn to the inner electrode rod 2. The external power supply is also connected to the outer shell electrode power connection 8, which is connected through the top support 5 to the bolts that are screwed into the outer shell electrode 1.

[0045] Fig. 9 A cross-sectional view of the top support 5 and the bottom support 6 is shown. The cross-sectional view shows the positions of the annular sealing rings in the top support 5 and the bottom support 6.

[0046] Figure 10-11 The results show that fatty acid conversion can be achieved by the basic Kolbe process. The voltage range used in the actual production of the Kolbe reaction is 2-12 V and the current density is 50 mA / cm 2 ~1.5A / cm 2 This example shows the main reaction under the default settings: the cathode and anode of the planar platinum electrode reaction, the distance between the two electrodes is 2 cm, the electrolyte is a mixture of decanoic acid and sodium hydroxide (the electrolyte contains the raw material - decanoic acid, which is also a fatty acid), the electrolyte solution is 35-50 degrees Celsius, pH 12-13, the voltage is 3.2V, and the current density is 190 mA / cm 2 Under this condition, the reaction is in the dimerization condensation reaction path; voltage 5V, current density 200 mA / cm 2 The reaction is in the disproportionation reaction path, voltage 10V, current density 1A / cm 2, the reaction is in the Hof-Mörster reaction pathway; in the dimerization condensation reaction, the fatty acid-decanoic acid platinum electrode with 10 carbon molecules containing carboxylic acid functional groups reacts to form the alkane fuel product octadecane. Octadecane is the main component of conventional fossil diesel and jet fuel in the aviation field. The composition of the product was confirmed by gas chromatography-mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) determination. These two advanced characterization techniques are cutting-edge methods for organic identification and quantification, and clearly show that the main product is the dimer fuel product octadecane formed by the combination of two decanoic acid molecules. By changing the voltage and current density, the main reaction path can be adjusted to the disproportionation reaction to form nonene and nonane; by continuing to increase the voltage and current density, the main reaction path can be adjusted to the Hof-Mörster reaction to form nonanal and nonanol.

[0047] Table 1 shows the detailed proportions of each reaction product under the Hof-Mörster reaction pathway, as follows:

[0048] Nonanal 30.8% Nonyl alcohol 37.1% Esters 3.9% Heptadecane 4.5% Octadecane 23.7%

[0049] The design of the reactor in the embodiment improves the structure of such reactors and the arrangement of components by simplifying the components, increasing the scalability of the process. This embodiment solves the cost problem by allowing simple, mass-produced rods and tubes to be made into high-performance electrochemical reactors that use electricity to synthesize biofuels. The design of the reactor allows the current density between the two electrodes to be significantly different, thereby causing substantial changes in the net products that the reactor may produce, especially when the applied voltage and current direction are reversed. When the catalytic performance of a single reactor unit is observed to decrease after a period of time, it can be simply replaced from the overall reactor for maintenance or recycling. The manufacturing process is simple and suitable for large-scale production, thereby enabling large-scale production of low-carbon biofuels. The embodiment can also simply handle increased pressure by using a relatively thick outer wall on the electrocatalytic tube.

[0050] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person familiar with the technical field can easily think of various equivalent modifications or substitutions within the technical scope disclosed by the present invention, and these modifications or substitutions should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention shall be based on the protection scope of the claims.

Claims

1. Application of a cylindrical flow reactor for electrosynthesis of biofuels by Kolbe reaction, characterized in that: The cylindrical flow reactor comprises an inner electrode rod located in the center, a cylindrical outer shell electrode and support members located at both ends of the reactor axial direction, wherein the support members are made of an electrically insulating material, and there is no electrode spacing membrane inside the reactor; the support members are divided into a top support member and a bottom support member; the inner electrode rod passes through the inner cavity formed by the outer shell electrode, and the radial width of the inner cavity is 20 mm; the electrolyte enters the chamber in the top support member through the electrolyte inlet, and then flows into the narrow inner cavity, and a reaction occurs in the channel through the current between the inner electrode and the outer electrode, and the product molecules then enter the chamber in the bottom support member and flow out from the electrolyte outlet The surface layer of the inner electrode rod and the inner surface layer of the outer shell electrode are coated with a platinum metal catalyst, the electrolyte solution is a mixed solution of sodium hydroxide and / or potassium hydroxide and fatty acids, and the pH value of the electrolyte solution before the electrochemical reaction is between 8 and 13; the top support and the bottom support are provided with an annular sealing ring at the portion contacting the outer shell electrode, and the top support and the bottom support are connected to the outer shell electrode by screwing in bolts; the raw material is biomass-derived fatty acid molecules, and the cylindrical flow reactor has a voltage range of 2 to 12 V and a current density of 50 mA / cm when the reaction is applied. 2 ~1.5A / cm 2 , the distance between the two electrodes is 2 cm, the electrolyte solution temperature is 35-50 degrees Celsius, and the pH is 12-13.

2. The use according to claim 1, characterized in that: The inner electrode rod is supported by the top support member and the bottom support member, and is connected to the inner electrode power connection point through the top support member; the outer shell electrode power connection point is arranged on the top support member, and is connected to the outer shell electrode through the top support member.

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

4. The use according to any one of claims 1 to 3, characterized in that: The cylindrical flow reactor in the application is used as the central reactor of the reactor stack type composed of cylindrical reactor units. The electrolyte solution containing reactant molecules and fuel products flows in parallel through each of the cylindrical reactor units. The reactor is cooled and maintained at a constant temperature using an external cooling device. The coolant is guided to flow through the outer surface of each cylindrical reactor. The reactant molecules and the 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.

5. The use according to claim 4, characterized in that: The central reactor realizes the conversion of three pathways, namely, disproportionation reaction, dimerization condensation reaction and Hof-Mörster reaction, by regulating the reaction parameters in the Kolbe reaction, and electrocatalytically converts bio-derived fatty acids into hydrocarbon, alcohol or aldehyde biofuels.

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