Biomass pyrolysis steam integrated coupling online quality improvement system and process based on SOEC

Abstract

The present invention relates to a biomass pyrolysis steam integrated coupling online quality improvement system and process based on SOEC, the system includes a steam generator, a solid oxide electrolytic cell SOEC, an electrochemical workstation, a fast pyrolysis furnace, the SOEC is a sandwich structure, from top to bottom, the air electrode electrolyte fuel electrode, the SOEC is fixed in a heating furnace through a hollow reaction tube, the air electrode of the SOEC is provided with an air inlet pipe a above the air electrode to connect the steam generator, and the fuel electrode of the SOEC is provided with a feed pipe b below to connect the fast pyrolysis furnace and an air pump; the feed pipe b is located inside the hollow reaction tube to form a double-layer reaction channel. Compared with the prior art, the present invention can significantly reduce the oxygen content of biomass pyrolysis oil and improve the calorific value and stability of bio-oil.

Description

Technical Field

[0001] The present invention belongs to the technical field of biomass energy utilization, and relates to an integrated coupling upgrading process for electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor based on SOEC (Solid Oxide Electrolysis Cell). Background Art

[0002] Biomass pyrolysis technology has the advantages of full-component utilization, strong raw material adaptability, and high conversion efficiency. It can efficiently convert biomass into liquid bio-oil with easy storage, transportation, and high energy density in a continuous and industrial production manner. Further upgrading and modification of it can obtain aviation fuel and high-value chemicals. Pyrolysis technology has a wide range of uses and flexible scales. Distributed biomass pyrolysis technology conforms to the characteristics of dispersed biomass resources in China and is one of the effective ways to truly realize the "local conditions" development and utilization of biomass, which helps China achieve the goals of carbon peak and carbon neutrality by 2060 at an early date.

[0003] The crude bio-oil obtained by biomass pyrolysis has low quality, complex composition, high oxygen content, low calorific value, high acid value, high viscosity, and poor stability, resulting in difficult application and treatment of bio-oil. This is mainly because the crude bio-oil contains a large number of oxygen-containing groups. The high oxygen content makes the lower calorific value of the crude bio-oil only 13 - 18 MJ / kg, far lower than 46 MJ / kg of vehicle gasoline; the presence of acid oxygen-containing groups causes the pH of the crude bio-oil to be about 2.5, with corrosiveness; the secondary reaction of highly active oxygen-containing functional groups leads to easy aging and polymerization of the crude bio-oil, making it difficult to store and transport for a long time. Therefore, it is necessary to refine and upgrade to improve the quality of the crude bio-oil so that it can be stably stored and transported.

[0004] There are various current methods for upgrading crude bio-oil. The most important methods include catalytic hydrogenation, catalytic cracking, catalytic esterification, emulsification, etc. Among them, catalytic hydrogenation is one of the most feasible methods for upgrading crude bio-oil at present. Catalytic hydrogenation is to remove the oxygen in the crude bio-oil in the form of H2O under the action of a catalyst at a certain temperature (>350 °C) and high hydrogen partial pressure (10 MPa - 20 MPa) to achieve the purpose of upgrading and modification. However, the reaction conditions of catalytic hydrogenation are relatively harsh (high temperature and high pressure), and an external hydrogen source is required. It can only be batch-reacted in a reaction kettle, reducing safety and economy and making continuous production difficult.

[0005] Patent CN118491439A: A reaction system for hydrogen production by aqueous-phase reforming coupled with catalytic hydrothermal liquefaction to produce bio-oil, which includes a catalytic hydrothermal liquefaction unit, a gas high-pressure separation and recycling unit, a product separation unit, and an aqueous-phase reforming hydrogen production unit. Among them, the liquefied wastewater separated by hydrothermal liquefaction is used as the water for biomass slurry preparation and the raw material for the aqueous-phase reforming reaction. The hydrogen and other substances obtained by high-pressure separation through a gas-liquid separator after the hydrothermal liquefaction reaction are directly compressed and boosted by a compressor and then sent back to the hydrothermal liquefaction reactor for reuse. The catalyst loaded in the hydrothermal liquefaction reactor has the functions of catalytic hydrogen production by aqueous-phase reforming of liquefied wastewater and hydro-upgrading of hydrothermal liquefaction bio-oil. In-situ hydrogen can be produced during the hydrothermal liquefaction reaction for in-situ hydro-upgrading of hydrothermal liquefaction bio-oil, improving the quality of bio-oil. However, in the whole preparation process, the liquefied wastewater needs to be recycled multiple times. In addition, the crude bio-oil needs to be first miscible with the catalyst to promote treatment, but then the upgraded bio-oil needs to be effectively separated from the solvent. This step not only increases the overall upgrading cost but also limits the treatment range to only the aqueous part of the crude bio-oil.

[0006] Patent CN202311469870.9: A method for hydrogenation and deoxygenation upgrading of biological oil to prepare biodiesel, which includes the steps: (a) Mix the pre-filtered raw biological oil with hydrogen and add it to a first fixed-bed reactor at a temperature of 150 °C - 300 °C for hydrogenation saturation and hydrodemetallization reactions. (b) Mix the product of step (a) with a sulfurizing agent and hydrogen, and carry out a hydrogenation and deoxygenation upgrading reaction under the action of a hydrogenation and deoxygenation upgrading catalyst. Through the method of the present invention, the hydrogenation process is divided into two stages. By the hierarchical configuration of the catalyst and the hierarchical control of the reaction temperature, the effects of hydrogenation saturation and hydrogenation and deoxygenation upgrading of biological oil are increased, and the quality of biodiesel is improved. However, this method belongs to a two-stage hydrogenation process, which is difficult to produce continuously and has limited popularization.

[0007] Electrochemical hydrogenation is an economical and environmentally friendly method for converting cheap raw materials into multifunctional chemicals. But it is all completed in a liquid-phase low-temperature system, and has the following defects: 1) The crude bio-oil to be upgraded needs to be miscible with the electrolyte, and the upgraded bio-oil needs to be separated from the electrolyte, increasing the upgrading cost and only being able to treat the aqueous component of the crude bio-oil; 2) This method generates in-situ H through electric energy at normal temperature and pressure, and there are problems of large mass transfer resistance and low reaction rate. Therefore, the reaction time of liquid-phase electrocatalytic hydrogenation is relatively long, and generally more than 4 h is required to reach the target conversion rate; 3) Limited by the previous two points, liquid-phase electrocatalytic hydrogenation needs to be carried out in batches, is difficult to produce continuously, and has poor compatibility with the front-end biomass pyrolysis to oil process.

[0008] CN202211084348.4 discloses a medium-temperature electrochemical upgrading process for biomass pyrolysis vapor. The key points of its technical solution are as follows: Biomass raw materials are continuously fed into a biomass fast pyrolysis furnace through a screw feeder for fast pyrolysis; the pyrolysis vapor is directly introduced into the cathode channel of a proton ceramic exchange membrane electrolyzer without cooling, and the steam generated by a steam generator is introduced into the anode of the proton ceramic exchange membrane electrolyzer; the proton ceramic exchange membrane electrolyzer is externally connected to a DC power supply to carry out an electrochemical reaction, thereby completing the upgrading of bio-oil in the pyrolysis vapor. This technology directly electrochemically hydrogenates and upgrades biomass pyrolysis vapor without condensation, significantly reducing the number of unsaturated bonds in biomass pyrolysis oil, reducing the acidity and viscosity of biomass pyrolysis oil, increasing its calorific value and stability, and improving the quality of biomass pyrolysis oil. However, the composition of biomass pyrolysis vapor is complex, containing organic substances such as tar, phenols, and acids, and the proton exchange membrane is highly sensitive to impurities in the vapor. These impurities may deposit on the surface of the catalyst or proton exchange membrane in the electrolyzer, resulting in membrane poisoning, blockage, or catalyst deactivation, reducing the efficiency of the electrochemical reaction. This leads to the need for additional gas purification steps, increasing the process complexity and cost. In addition, the proton ceramic exchange membrane electrolyzer is equipped with expensive noble metal catalysts, and the cost of these materials is relatively high. Once deactivation or performance degradation occurs, they may need to be replaced frequently, especially in large-scale industrial applications, which will significantly increase the manufacturing and maintenance costs of the equipment. The normal operation of the proton exchange membrane depends on appropriate humidity, neither too dry nor too wet. During the electrochemical upgrading process, water vapor is both a reactant and a reaction product, and how to maintain the water management balance inside the electrolyzer is a challenge.

[0009] In addition, due to the hydrogen production performance limitations of the electrolyzer type adopted in CN202211084348.4, if a continuous hydrogenation reaction is to be achieved, it must be designed as a symmetric double electrolyzer structure. This design makes the pyrolysis gas enter the reactor in a parallel structure with the reaction surface, resulting in a large amount of pyrolysis gas being unable to effectively contact the reaction surface. At the same time, due to the time relaxation effect when the reaction interface on the same side contacts the pyrolysis gas, this further exacerbates the problems of concentration polarization (between the upper and lower reaction surfaces) and activation polarization (the difference between the left and right reaction surfaces in the same electrolyzer on the same side). All these factors greatly reduce the hydrogen production performance of the electrolyzer and have an adverse impact on the reaction efficiency and product selectivity. In addition, the double electrolyzer structure also cannot effectively collect the products. Summary of the Invention

[0010] The purpose of the present invention is to overcome the defects of the above-mentioned existing technologies and provide a SOEC-based integrated coupling upgrading system and process for electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor, which can continuously hydrodeoxygenate crude bio-oil with a high deoxygenation rate and a high selectivity for aromatic liquid-phase products.

[0011] The object of the present invention can be achieved by the following technical solutions: A biomass pyrolysis vapor electrochemical hydrogenation and deoxygenation integrated coupling upgrading system based on SOEC, the system includes a steam generator, an SOEC, an electrochemical workstation, and a rapid pyrolysis furnace. The SOEC has a sandwich structure, which is an air electrode - electrolyte - fuel electrode from top to bottom in sequence. It is characterized in that the SOEC is fixed in a heating furnace through a hollow reaction tube. An inlet pipe a is provided above the air electrode of the SOEC to communicate with the steam generator, and a feed pipe b is provided below the fuel electrode of the SOEC to communicate with the rapid pyrolysis furnace and an air pump; the feed pipe b is located inside the hollow reaction tube, forming a double-layer reaction channel.

[0012] The water vapor generated by the steam generator is electrolyzed on the surface of the air electrode of the SOEC to generate H, which enters the fuel electrode side and reacts with the gas from the pyrolysis of biomass in the rapid pyrolysis furnace through a gas-solid phase electrochemical hydrogenation upgrading reaction. The resulting reaction product stream moves in a countercurrent manner in the same chamber of the double-layer reaction channel, thereby forming the conditions of a continuous stirred tank reactor to achieve in-situ deep hydrogenation upgrading of bio-oil.

[0013] Further, the steam generator is connected to the air electrode of the SOEC through the inlet pipe a wrapped by a heating pipe a; the lower port of the inlet pipe a is 1.0 - 1.5 cm away from the air electrode of the SOEC.

[0014] Further, the SOEC with a sandwich structure is a commercially available product or is prepared by existing technologies. Preferably, the air electrode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ -BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ;

[0015] The electrolyte is BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ;

[0016] The fuel electrode is Nio-BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ;

[0017] The air electrode and the fuel electrode are respectively connected to the electrochemical workstation, and the electrochemical workstation applies a voltage to the SOEC to generate H.

[0018] Furthermore, the fast pyrolysis furnace directly enters the fuel electrode of the SOEC through the feed pipe b wrapped by the heating pipe b; the upper port of the feed pipe b is 0.5 - 1.0 cm away from the fuel electrode of the SOEC; the feed pipe b is located inside the hollow reaction tube, and the pipe diameter ratio is 1:2.5. The length of the preheating part of the feed pipe b in the heating furnace is 35 cm;

[0019] The fast pyrolysis furnace is connected in parallel with an air pump, and air is continuously pumped into the feed pipe b through the air pump to drive the pyrolysis gas to the fuel electrode of the SOEC.

[0020] Furthermore, the hydrodeoxygenation product is output to the cooling system through the discharge pipe wrapped by the heating pipe c, and the gas-phase product is collected by the gas bag.

[0021] The present invention also provides a SOEC-based integrated coupling upgrading process for biomass pyrolysis vapor electrochemistry hydrogenation saturation and deoxygenation using the above system, including the following steps:

[0022] S1: The water vapor generated by the steam generator is introduced into the air electrode of the SOEC at a flow rate of 80 - 90 mL / min and a temperature of 200 - 250 °C;

[0023] S2: The heating furnace heats the SOEC to 600 - 700 °C at a heating rate of 5 - 8 °C / min;

[0024] S3: The electrochemical workstation applies a constant voltage to the SOEC, and the voltage is maintained at 1.3 - 1.4 V to enable the SOEC to enter the electrolysis mode, and a large amount of H is produced at the fuel electrode at the lower end of the SOEC;

[0025] S4: After the biomass raw material is pyrolyzed in the fast pyrolysis furnace, it directly enters the fuel electrode of the SOEC through the feed pipe b;

[0026] S5: At the same time, the air flow rate pumped into the feed pipe b by the air pump is controlled to be 50 - 60 mL / min to drive the pyrolysis gas to the fuel electrode of the SOEC;

[0027] S6: The feed flow input through the feed pipe b flows perpendicular to the fuel electrode area, and the pyrolysis gas undergoes a gas-solid phase electrochemical hydrogenation upgrading reaction at the fuel electrode of the SOEC. The resulting reaction product stream moves in a countercurrent manner in the same chamber, thus forming the conditions of a continuous stirred tank reactor;

[0028] S7: The reaction product is transported to the cooling system through the discharge pipe to obtain the condensed liquid-phase product;

[0029] S8: The non-condensable gas is collected by the gas bag.

[0030] Further, the water content in the water vapor generated by the steam generator in step S1 is 3%-10%;

[0031] The mass flowmeter controls the flow rate of the water vapor, and the temperature of the water vapor is controlled by heating the inlet pipe a through the heating pipe a.

[0032] Further, the pyrolysis conditions of the fast pyrolysis furnace in step S4 are: heating up to 500-600 °C at a heating rate greater than 10000 °C / s and staying for 1 s to complete fast pyrolysis;

[0033] The biomass raw materials include wood processing residues, forestry logging residues or crop straw agricultural residues.

[0034] Further, the temperature of the heating pipe b wrapped outside the feed pipe in step S4 is 300-350 °C to prevent condensation. The fast pyrolysis furnace needs to be continuously purged with nitrogen at a rate of 0.2 L / h at room temperature for 0.5 h before the reaction.

[0035] Further, the discharge pipe described in step S7 is heated by a heating pipe c, and the heating temperature is 120-150 °C;

[0036] The temperature of the cooling system is controlled at -5 to -1 °C.

[0037] The Solid Oxide Electrolysis Cell (SOEC) has a sandwich structure, which is an air electrode - electrolyte - fuel electrode from top to bottom. The SOEC can work normally in the range of 500 °C - 850 °C and has great compatibility with the biomass pyrolysis process. Based on the characteristics of fast reaction rate and matching working range with biomass pyrolysis of the SOEC, the present invention proposes a process for online electrochemical upgrading of biomass pyrolysis steam based on SOEC. The pyrolysis vapor does not need to be condensed and directly enters the SOEC for online electrochemical hydrogenation upgrading. The water vapor decomposes into oxygen and hydrogen protons at the air electrode, and the hydrogen protons pass through the electrolyte to reach the fuel electrode, where a gas-solid phase reaction occurs with the biomass pyrolysis vapor at the three-phase interface of the fuel electrode, thereby converting the unsaturated functional groups in the pyrolysis vapor into saturated functional groups and realizing the quality improvement of bio-oil online.

[0038] Based on the SOEC hydrogen production technology, the present invention proposes a new process for integrated coupling and online upgrading of electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor. Through steps such as rapid biomass pyrolysis, SOEC voltage control, inlet and feed flow rate regulation, interface relationship design, and gas-solid phase electrochemical reaction, the present invention can realize the integrated coupling upgrading of online electrochemical hydrogenation saturation - deoxygenation of biomass pyrolysis vapor. Specifically: 1. Voltage is a key parameter for controlling the electrochemical reaction, which directly affects the change in free energy of the reaction ( ). The voltage control needs to meet the following basic thermodynamic and kinetic relationships: , where ΔG is the Gibbs free energy of the reaction, n is the number of electron transfers, F is the Faraday constant, and E is the electromotive force (voltage) of the battery. When the voltage is too low, the reaction rate may not be sufficient to drive the hydrogenation and deoxygenation reactions; when the voltage is too high, unwanted side reactions (electrode degradation) may be triggered. Therefore, the selection of voltage must find a balance between effective hydrogenation reactions and minimizing side reactions. 2. The control of the flow rates of the inlet gas and the feed affects the residence time in the reactor ( ), thus affecting the adequacy of the gas-solid reaction. The relationship between the residence time and the flow rate generally follows the following formula: , where V is the effective volume of the reactor and Q is the volumetric flow rate of the inlet gas / feed. A shorter residence time may result in incomplete reactions, while an overly long residence time may lead to the formation of by-products. The flow rates of the inlet gas and the feed need to be optimized according to the size of the reactor, the reaction rate, and the target yield of the reaction products. Interface design, especially the contact area and structure between the electrode and the electrolyte, has an important impact on the effectiveness of the reaction. The reaction rate is usually proportional to the effective surface area 𝐴 of the electrode 𝑒𝑓𝑓 , which can be enhanced by improving the interfacial activity or optimizing the structural design. The rate of the gas-solid electrochemical reaction is also limited by the mass transfer process, especially the diffusion of reactants and products between the electrode and the reactant gas phase. The mass transfer rate is often described by the Sherwood number 𝑆ℎ and the Peclet number 𝑃𝑒: , , is the mass transfer coefficient, L is the characteristic length, D is the diffusion coefficient, U is the flow rate. Therefore, the gas flow rate and the reactor design need to be balanced to ensure that the mass transfer rate matches the reaction rate. Compared with the traditional thermal catalytic hydro-upgrading method, the pyrolysis vapor of biomass in the present invention does not need to be condensed into crude bio-oil and can be upgraded online, avoiding energy loss; at the same time, no external hydrogen source is required, and redundant wind, light, water, and electricity can be consumed, greatly reducing the upgrading cost. The successful implementation of the present invention is expected to break through the bottleneck problems of the current complex and high-cost process for preparing high-value fuels by biomass pyrolysis, and contribute to the industrial promotion of the high-value utilization technology of biomass pyrolysis.

[0039] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0040] (1) In the present invention, SOEC electrolytic hydrogen production is coupled with biomass pyrolysis hydrogenation technology. Among them, the SOEC adopted has higher energy efficiency. Since SOEC operates at high temperatures (usually between 500 °C and 850 °C), external thermal energy can directly participate in the electrolysis reaction, thereby reducing the required electrical energy input. Under high-temperature conditions, part of the reaction energy is provided by heat, so the voltage required for the electrolysis reaction is lower and the electrical energy utilization rate is higher. This makes the hydrogenation upgrading system of the present invention more energy-efficient. SOEC can utilize the waste heat from industrial processes or the thermal energy of renewable energy sources (such as solar energy) to heat the electrolytic cell. This "synergy of heat and electricity" not only reduces the external electrical energy demand but also makes the entire system more sustainable, especially when integrated with energy systems such as high-temperature industrial processes or solar thermal power plants. In addition, the reaction rate in low-temperature electrolysis (such as PEMEC and alkaline electrolytic cells) is limited by temperature, and the hydrogen production efficiency is low. The working characteristics of SOEC enable this system to dispense with an external hydrogen source, and the high-temperature operating conditions contribute to increasing the hydrogen production. Hydrogen can be directly produced by utilizing redundant wind energy, solar energy, and hydropower through this system. Therefore, this system is very suitable for large-scale hydrogenation upgrading industry.

[0041] (2) The new process of the present invention can carry out the reaction without a catalyst through system design and simplified process flow, avoiding problems such as short catalyst life, easy coking and deactivation, the process of catalyst regeneration or replacement, low yield of upgraded bio-oil, and low H / C ratio. This is different from the expensive and operation-condition-sensitive metal catalysts required for traditional hydrocracking, greatly enhancing the economic feasibility of the high-value utilization of biomass pyrolysis. Moreover, this system can widely adapt to various biomass raw materials, improving the universality and application scope of the process, and contributing to promoting the industrial promotion and market application of biomass pyrolysis technology.

[0042] (3) By coupling SOEC electrolytic hydrogen production with biomass pyrolysis hydrogenation technology in the present invention, the design of using an air pump to drive the pyrolysis gas into the hydrogenation reactor enables the biomass pyrolysis steam to be directly upgraded online without being condensed into crude bio-oil, successfully avoiding the steps of condensation and reheating in the traditional process. This design not only makes the reaction conditions milder and the device structure more simplified but also, by combining the pyrolysis temperature with the working temperature of SOEC and optimizing the feeding process, significantly reduces the energy consumption. Through more efficient resource utilization and energy conversion, this system effectively reduces the cost of preparing high-value fuels from biomass pyrolysis, bringing significant economic advantages to industrial applications.

[0043] (4) The double-layer reaction channel designed in the present invention enables the feed stream and the reaction product stream to move in a countercurrent manner in the same chamber of the reactor. This can ensure that there is always a concentration gradient between the reactants (such as hydrogen, pyrolysis gas) and the reaction products (such as partially upgraded bio-oil), guaranteeing mass transfer and reaction rates. Under the countercurrent configuration, the contact between the reactants and the product stream is more precise and controllable, reducing the occurrence of unnecessary side reactions. Especially in a high-temperature environment, the formation of coke or other undesirable by-products is avoided. This design helps to improve the upgrading effect of bio-oil and the purity and quality of the final product.

[0044] (5) The design of the countercurrent mode is very suitable for continuous reaction processes. The reactants and products can flow continuously, without the need for frequent feed and discharge adjustments. The current electrochemical hydrogenation process is usually carried out in a liquid-phase low-temperature system, which requires the crude bio-oil to be miscible with the electrolyte and separated from the electrolyte after upgrading. This not only increases the cost but also limits the processing of only the aqueous components of the crude bio-oil. The liquid-phase electrocatalytic hydrogenation reaction time is relatively long, usually taking more than 4 hours to reach the target conversion rate. This type of method needs to be carried out in batches and is difficult to achieve continuous production, with poor compatibility with the front-end biomass pyrolysis to bio-oil process. This system can continuously hydrodeoxygenate the crude bio-oil, which is particularly important for on-line deep hydro-upgrading on an industrial scale, improving the production efficiency and economy of the entire process. The countercurrent operation mode can also reduce the volume required for the reactor, making the equipment more compact, saving space and material costs, and thus reducing the capital expenditure and maintenance costs in industrial applications.

[0045] (6) The present invention adopts a SOEC electrolytic cell and a single electrolytic cell structure. This design can better control the gas flow distribution, enabling the reactor to form reaction conditions similar to a continuous stirred tank, avoiding problems such as uneven gas flow and insufficient reaction in a double electrolytic cell, ensuring that all pyrolysis gas is in full contact with the reaction interface, thereby optimizing the utilization rate of hydrogen and achieving on-line deep hydro-upgrading of bio-oil. On the premise of ensuring the required hydrogen production, the single electrolytic cell structure effectively avoids the phenomena of concentration polarization and activation polarization that may occur in the double electrolytic cell design. The single electrolytic cell can maintain efficient reaction under a wider range of reaction conditions, adapt to more diverse raw materials and operating conditions, and improve the scalability and applicability of the system.

[0046] In addition, the single electrolytic cell design can optimize the hydrogen reaction sites and form a single hydrogen concentration gradient, further realizing the gradient diffusion-gradient reaction process of pyrolysis gas. The control of the hydrogen concentration gradient helps with the dynamic regulation during the reaction process, making the reaction between hydrogen and pyrolysis gas more balanced and efficient. This innovative design significantly improves the reaction selectivity, and ultimately the reaction selectivity exceeds 97%. Through this technological innovation, the continuous hydrogenation reaction can be maintained stably at a higher reaction selectivity and efficiency, and the overall performance and stability of the reactor can be significantly improved. Description of the Drawings

[0047] Figure 1 It is a schematic diagram of an integrated coupling upgrading system for electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor based on SOEC.

[0048] Reference Numerals: 1 Steam Generator; 2 Mass Flowmeter; 3 Heating Pipe a; 4 Inlet Pipe a; 5 SOEC; 6 Heating Furnace; 7 Hollow Reaction Tube; 8 Feed Pipe b; 9 Electrochemical Workstation; 10 Heating Pipe b; 11 Fast Pyrolysis Furnace; 12 Air Pump; 13 Heating Pipe c; 14 Discharge Pipe; 15 Cooling System; 16 Gas Bag.

[0049] Figure 2 It is an analysis image of GC-MS of the product of the integrated coupling upgrading of electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor based on SOEC in Example 1. Raw material: Pine biomass particles.

[0050] Figure 3 It is an analysis image of GC-MS of the product of the integrated coupling upgrading of electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor based on SOEC in Example 2. Raw material: Redwood biomass particles.

[0051] Figure 4 It is an analysis image of gas chromatography-mass spectrometry (PY-GC-MS) of pine biomass particles after pyrolysis in Comparative Example 1. Detailed Embodiments

[0052] The present invention will be described in detail below with reference to the drawings and specific embodiments.

[0053] An integrated coupling upgrading system for electrochemical hydrogenation saturation and deoxygenation of biomass pyrolysis vapor based on SOEC, as Figure 1 shown: It includes 1 Steam Generator; 2 Mass Flowmeter; 3 Heating Pipe a; 4 Inlet Pipe a; 5 SOEC; 6 Heating Furnace; 8 Feed Pipe b; 7 Hollow Reaction Tube; 9 Electrochemical Workstation; 10 Heating Pipe b; 11 Fast Pyrolysis Furnace; 12 Air Pump; 13 Heating Pipe c; 14 Discharge Pipe; 15 Cooling System; 16 Gas Bag.

[0054] Among them, SOEC 5 has a sandwich structure, which from top to bottom is the SOEC air electrode - electrolyte - fuel electrode. The air electrode is La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ -BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ;

[0055] The electrolyte is BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ;

[0056] The fuel electrode is Nio - BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ ;

[0057] The SOEC 5 is fixed in the heating furnace 6 through the hollow reaction tube 7. An air inlet pipe a4 is provided above the air electrode of the SOEC 5 to communicate with the steam generator 1. A feed pipe b8 is provided below the fuel electrode of the SOEC 5 to communicate with the fast pyrolysis furnace 11; the feed pipe b8 is located inside the hollow reaction tube 7, forming a double-layer reaction channel;

[0058] The steam generator 1 is connected to the air electrode of the SOEC 5 through the air inlet pipe a4 wrapped by the heating pipe a3; the lower port of the air inlet pipe a4 is 1.0 - 1.5 cm away from the air electrode of the SOEC 5. The water vapor generated by the steam generator 1 is introduced into the air electrode,

[0059] The fast pyrolysis furnace 11 directly enters the fuel electrode of the SOEC 5 through the feed pipe b8 wrapped by the heating pipe b10; the upper port of the feed pipe b8 is 0.5 - 1.0 cm away from the fuel electrode of the SOEC; the length of the preheating part of the feed pipe b8 in the heating furnace 5 is 35 cm;

[0060] After pyrolysis in the fast pyrolysis furnace 11, the biomass raw material is separated by a gas-liquid separator. The gas enters the fuel electrode from the bottom up through the feed pipe b8. The air electrode and the fuel electrode are respectively connected to an electrochemical workstation 9, and the electrochemical workstation 9 applies a voltage to the SOEC 5. The water vapor transported by the steam generator 1 is electrolyzed on the surface of the air electrode to generate H, which passes through the electrolyte and enters the fuel electrode side, where it undergoes a gas-solid phase electrochemical hydro-upgrading reaction with the gas from the pyrolysis of biomass in the fast pyrolysis furnace 11. The resulting reaction product stream flows downward in the space between the hollow reaction tube 7 and the feed pipe b8 in the double-layer reaction channel, moving countercurrently with the pyrolysis gas in the same chamber, thus forming the conditions of a continuous stirred tank reactor to achieve in-situ deep hydro-upgrading of bio-oil.

[0061] An air pump 12 is connected in parallel to the fast pyrolysis furnace 11, and air is continuously pumped into the feed pipe b8 through the air pump 12 to drive the pyrolysis gas to the fuel electrode of the SOEC5.

[0062] The bottom of the hollow reaction tube 7 extends outside the heating furnace 6, and a discharge pipe 14 is connected to its side wall. The hydrodeoxygenation product is output from the hollow reaction tube 7 to the cooling system 15 through the discharge pipe 14 wrapped by the heating pipe c13, and the gas-phase product is collected by the gas bag 16.

[0063] O generated by the electrolysis of water vapor on the surface of the air electrode 2 diffuses into the cavity of the heating furnace 6 to increase the oxygen partial pressure of the air electrode, balance the partial pressure caused by the feed flow at the fuel electrode, and ensure the normal progress of the electrochemical reaction.

[0064] The technical solution of the present application will be described in detail below in conjunction with specific embodiments. The raw materials and equipment used in each embodiment are conventional raw materials and equipment in the art unless otherwise specified. For example, nano-graphite powder can be a commercially available product from Alfa company with APS7-11 micron, 99%.

[0065] Example 1

[0066] I. Preparation of a solid oxide electrolytic cell (SOEC)

[0067] Mix NiO and BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ(It can be a commercially available product or prepared by the methods reported in the existing literature. In this example, the reference document DOI: 10.1016 / j.jpowsour.2011.08.047 is used to prepare by the solid-phase method) It is composed of a mixture in a mass ratio of 6:4. Subsequently, 10 wt.% of nano-graphite powder of the total mass of the obtained mixture is added to obtain the composite fuel electrode powder. Weigh 0.30 g of the composite fuel electrode powder and pour it into a pressing die with a diameter of 12 mm to obtain the composite fuel electrode substrate. 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ The electrolyte powder is sprinkled on the composite fuel electrode substrate, and uniaxially co-pressed at a pressure of 100 MPa for 60 s. After pressure relief and demolding, a green semi-electrolytic cell is obtained. It is calcined in an air atmosphere at 1300 °C for 6 h to sinter the electrolyte densely, and a fuel electrode-supported semi-electrolytic cell is obtained.

[0068] The electrolyte powder BaZr 0.1 Ce 0.7 Y 0.1 Yb 0.1 O 3-δ and La 0.6 Sr 0.4 Co 0.2 Fe 0.8 O 3-δ (It can be a commercially available product or prepared by the methods reported in the existing literature. In this example, the reference document DOI: 10.3390 / ma17040869 is used to prepare by the sol-gel method) The powders are mixed in a mass ratio of 7:3 to obtain the composite air electrode powder. The obtained composite air electrode powder is mixed with a 6 wt% ethyl cellulose-terpineol binder in a mass ratio of 1:1.5 to prepare the composite air electrode slurry. The obtained composite air electrode slurry is uniformly coated on the electrolyte side of the fuel electrode-supported semi-electrolytic cell and calcined in an air atmosphere at 1000 °C for 1 h to obtain a complete SOEC. The SOEC is fixed at the top of the feed pipe b8 using a high-temperature ceramic adhesive.

[0069] II. Integrated coupling upgrading of biomass pyrolysis vapor by electrochemical hydrogenation saturation and deoxygenation

[0070] The biomass raw materials include wood processing residues, forestry logging residues, and crop straw agricultural residues. In this example, purchased pine biomass pellets are used as the biomass raw material in this example. Before upgrading, the raw materials are first placed in an oven and dried at 120 °C, weighed every 5 h until the mass of the pine biomass pellets no longer changes, and the total drying time is 50 h.

[0071] S1: The steam generator 1 generates water vapor with a water content of 3%. The mass flowmeter 2 controls the flow rate at 85 mL / min. The heating pipe a3 heats the inlet pipe a4 to a temperature of 220 °C to prevent condensation, and the water vapor is introduced into the air electrode of the SOEC 5. The distance between the lower port of the inlet pipe a4 and the air electrode of the SOEC 5 is controlled at 1.0 cm;

[0072] S2: The heating furnace 6 heats the SOEC5 to 700 °C at a heating rate of 8 °C / min;

[0073] S3: The electrochemical workstation 9 applies a constant voltage to the SOEC5, and the voltage is maintained at 1.3 V to make the SOEC 5 enter the electrolysis mode. A large amount of H is produced at the fuel electrode at the lower end of the SOEC 5;

[0074] S4: The pine biomass particles dried for 50 h are pyrolyzed in the fast pyrolysis furnace 11 (heated to 500 °C at a heating rate greater than 10000 °C / s and held for 1 s to complete fast pyrolysis), and then directly enter the fuel electrode of the SOEC 5 through the feed pipe b8 without cooling. The distance between the upper port of the feed pipe b8 and the fuel electrode of the SOEC 5 is 1.5 cm. The heating pipe b10 is at a temperature of 300 °C to prevent condensation. The pyrolysis furnace needs to be continuously purged with nitrogen at a rate of 0.2 L / h for 0.5 h at room temperature before the reaction;

[0075] S5: The air pump 12 continuously pumps air into the feed pipe b8 at a flow rate of 55 mL / min, driving the pyrolysis gas to the fuel electrode of the SOEC 5;

[0076] S6: The feed stream flows perpendicular to the fuel electrode area in the feed pipe b8. The distance between the upper port of the feed pipe b8 and the fuel electrode of the SOEC 5 is controlled at 1.0 cm. The pyrolysis gas undergoes a gas-solid phase electrochemical hydrogenation and upgrading reaction at the fuel electrode of the SOEC 5, and the reaction product stream moves in a countercurrent manner in the same chamber, thus forming the conditions of a continuous stirred tank reactor.

[0077] S7: The reaction product is transported by the discharge pipe 14 to the cooling system 15 to obtain the condensed liquid-phase product. The heating pipe c12 is heated to a temperature of 120 °C;

[0078] S8: The non-condensable gas is collected by the gas bag 16.

[0079] Example 2

[0080] I. Preparation of solid oxide electrolytic cell (SOEC)

[0081] Step (i) is the same as in Example 1 to obtain the solid oxide electrolytic cell.

[0082] II. Integration of biomass pyrolysis vapor electrochemical hydrogenation saturation and deoxygenation

[0083] Biomass raw materials include wood processing residues, forestry logging residues, and crop straw agricultural residues. In Example 2, purchased mahogany biomass pellets were used as the biomass raw material for this example. Before upgrading, the raw materials were placed in an oven and dried at 120 °C, weighed every 5 h until the mass of the mahogany biomass pellets no longer changed, and the total drying duration was 50 h.

[0084] S1: The steam generator 1 generates water vapor with a water content of 3%, the flow rate is controlled by the mass flow meter 2 to be 80 mL / min, the heating pipe a3 heats the inlet pipe a4, and the temperature is 250 °C to prevent condensation. The water vapor is introduced into the air electrode of the SOEC 5, and the lower port of the inlet pipe a4 is controlled to be 1.5 cm away from the air electrode of the SOEC 5;

[0085] S2: The heating furnace 6 heats the SOEC 5 to 650 °C at a heating rate of 5 °C / min;

[0086] S3: The electrochemical workstation 9 applies a constant voltage to the SOEC 5, and the voltage is maintained at 1.4 V to make the SOEC 5 enter the electrolysis mode, and a large amount of H is produced at the fuel electrode at the lower end of the SOEC 5;

[0087] S4: The mahogany biomass pellets dried for 50 h are pyrolyzed in the fast pyrolysis furnace 11 (heated to 600 °C at a heating rate greater than 10000 °C / s and held for 1 s to complete fast pyrolysis), and without cooling, they directly enter the fuel electrode of the SOEC 5 through the feed pipe b8. The upper port of the feed pipe b8 is 1 cm away from the fuel electrode of the SOEC 5, and the temperature of the heating pipe b10 is 350 °C to prevent condensation. The pyrolysis furnace needs to be continuously purged with nitrogen at a rate of 0.2 L / h at room temperature for 0.5 h before the reaction;

[0088] S5: The air pump 12 continuously pumps air into the feed pipe b8 at a flow rate of 60 mL / min, driving the pyrolysis gas to the fuel electrode of the SOEC 5;

[0089] S6: The feed stream flows perpendicular to the fuel electrode region in the feed pipe b8. The upper port of the feed pipe b8 is controlled to be 0.5 cm away from the fuel electrode of the SOEC 5. The pyrolysis gas undergoes a gas-solid phase electrochemical hydrogenation upgrading reaction at the fuel electrode of the SOEC 5, and the reaction product stream moves in a countercurrent manner in the same chamber, thus forming the conditions of a continuous stirred tank reactor.

[0090] S7: The reaction products are transported to the cooling system 15 through the discharge pipe 14 to obtain the condensed liquid-phase products, and the heating temperature of the heating pipe c12 is 150 °C;

[0091] S8: The non-condensable gas is collected by the gas bag 16.

[0092] Comparative Example 1

[0093] Pyrolysis-gas chromatography-mass spectrometry (PY-GC-MS) is an analytical method that combines pyrolysis technology and gas chromatography-mass spectrometry. In this comparative example, pine biomass pellets were used as raw materials, and PY-GC-MS was used to analyze the product distribution before hydrogenation. The specific equipment parameters of PY-GC-MS are as follows: the pyrolysis mode is set to the flash direct pyrolysis mode. Before the experiment, the experimental quartz pyrolysis tube was cleaned with a tube furnace and an ultrasonic cleaner, and quartz wool was inserted. First, a pre-experiment was carried out with a blank sample to ensure that there were no other contaminants in the analysis system. The instrument carrier gas is high-purity nitrogen, the carrier gas flow rate is 50 mL / min, the temperature is raised to 700 °C at a heating rate of 10 °C / ms and maintained for 15 s, the transfer line temperature is stabilized at 300 °C, and the pyrolysis products are injected into the GC through a fused silica transfer tube. To reduce and avoid the influence of secondary reactions on the weight loss characteristics, the sample amount used is controlled at 1 μL. The chromatographic column is Restek VMS (inner diameter 30 m × 0.25 mm, film thickness 1.4 μm), the chromatographic temperature rising conditions are to hold at 40 °C for 60 s and then raise the temperature to 240 °C at a rate of 8 °C / min and hold for 24 min, the split ratio is 1:50, the chromatograph-mass spectrometer interface temperature is 250 °C, and the remaining temperature is controlled at 200 °C to prevent the condensation of pyrolysis products.

[0094] The liquid-phase products prepared in Examples 1-2 were analyzed using a gas chromatograph-mass spectrometer (GC-MS), and the gas-phase products were analyzed using a gas chromatograph-flame ionization detector (GC-FID). The GC-MS quantitative method is the internal standard method and the effective carbon number method. An appropriate reference substance (internal standard compound, dichloromethane was selected here) was added to the sample to be measured, and the ratio of the response values of the compound to be measured and the internal standard compound (referred to as the relative response factor) was calculated. Quantitative analysis was carried out based on this relative response factor and the content of the added internal standard compound, which is called the internal standard method. The specific calculation can be carried out by the following formula:

[0095]

[0096] where and are the contents of the compound to be measured and the internal standard compound respectively, is the relative response factor, and are the peak area ratios of the compound to be measured and the internal standard compound.

[0097] The relative response value for GC-FID is mainly related to the effective carbon number of the molecule. Therefore, the ratio of the response values of the compound to be measured and the internal standard compound can be calculated by the effective carbon number method. The effective carbon number method means that the relative molar response value (RMR) of a substance is proportional to the number of carbon atoms in the molecule. That is, the amount of substance of the compound to be measured can be calculated by the following formula:

[0098]

[0099] As Figure 4 shown, where Py-GCMS represents pyrolysis-gas chromatography-mass spectrometry, characterizing the product distribution before hydrogenation, and GC spectra represents gas chromatogram, characterizing the product distribution after hydrogenation. The GC-MS results show that the main products of rapid pyrolysis in Comparative Example 1 mainly include furan group-derived compounds and a small amount of alkenes and aromatic-derived compounds. Among them, the total content of furan, 2-acetylfuran, and 5-methylfurfural accounts for more than 80% of the overall pyrolysis products, and the pyrolysis products are more complex, with some coking products appearing, and the contents of oxygen-containing compounds and aromatics increasing significantly.

[0100] As Figure 2 shown, GC spectra represents gas chromatogram, characterizing the product distribution after hydrogenation. The GC-MS results show that the main liquid-phase products after the integrated coupling upgrading of electrochemically hydrogenating and deoxygenating the biomass pyrolysis vapor based on SOEC are monocyclic aromatic hydrocarbons, containing a small amount of furan group-derived compounds and oxygen-containing compounds. Compared with Comparative Example 1, the SOEC electrocatalytic hydrogenation in Example 1 has an obvious hydrogenation upgrading effect on the pyrolysis products, and the main products are reduced from 27 to 12. The proportion of oxygen-containing compounds in the products decreases significantly, and there are no polymerization products. The selectivity of the liquid-phase products of monocyclic aromatic hydrocarbons exceeds 80%, and the deoxygenation rate exceeds 90%.

[0101] As Figure 3 shown, GC spectra represents gas chromatogram, characterizing the product distribution after hydrogenation. In Example 2, the relative content of furan group derivatives increases, and the types and relative contents of polymerization products decrease. In addition to a small amount of α-pyrone obtained by planar hydrogen transfer from vinyl vinyl ketone [O=C=CH-CH=CH-CHO], the products only contain monocyclic aromatic hydrocarbon compounds and no other liquid-phase substances. The selectivity of the aromatic liquid-phase products in Example 2 exceeds 97%, the proportion of oxygen-containing compounds decreases significantly, and the deoxygenation rate also exceeds 90%.

[0102] Table 1 Properties of calorific value and stability parameters after hydrogenation upgrading of comparative examples and Examples 1 and 2

[0103]

[0104] The data in Table 1 show that hydro-upgrading significantly improves the calorific value and stability of bio-oil. The higher heating values of Example 1 and Example 2 are 58.2 MJ / kg and 57.4 MJ / kg respectively, which are significantly higher than 17.8 MJ / kg of the comparative example. The lower heating value also increases from 13.1 MJ / kg of the comparative example to 41.7 MJ / kg and 40.2 MJ / kg. This indicates that the calorific value of bio-oil can be greatly improved through the hydro-upgrading process, approaching the level of traditional fossil fuels. In addition, the acid value after hydrotreatment decreases from 27.3 mgKOH / g of the comparative example to 10.1 - 11.3 mgKOH / g, indicating a significant reduction in acidic components and improved chemical stability. In terms of viscosity, the viscosities of Example 1 and Example 2 are both 4.5 - 4.6 cP, which is significantly lower than 15.1 cP of the comparative example, indicating better fluidity of bio-oil and improved processing and use performance. Most significantly, the oxygen content decreases from 47.2 wt.% of the comparative example to 3.6 - 4.2 wt.% after hydro-upgrading, greatly improving the calorific value and combustion performance. Overall, hydro-upgrading effectively improves the quality of bio-oil, optimizes it in key parameters such as calorific value, acid value, viscosity and oxygen content, and shows better fuel characteristics and industrial application potential.

[0105] In view of the current limitations of electrochemical hydrogenation of bio-oil being confined to a liquid-phase low-temperature hydrogenation system, which is difficult to operate continuously, requires separation of hydrogenated bio-oil from the electrolyte, and has a low compatibility with the front-end biomass pyrolysis process. The present invention utilizes the characteristic that the operating range of SOEC matches biomass pyrolysis, and proposes a system and process for on-line electrochemical upgrading of biomass pyrolysis vapor based on SOEC. This system features mild reaction conditions and a simple device structure, and can perform effective electrochemical hydrogenation and deoxygenation under medium temperature, atmospheric pressure, low energy, and highly controllable reaction and input conditions, avoiding the high temperature, high pressure, and complex catalyst requirements common in traditional processes. This not only simplifies the equipment structure, reduces the operating cost, but also improves the safety and energy utilization efficiency of the process. The mildness is reflected in that compared with traditional hydrogenation processes, there is no need to carry out reactions under high pressure (>100 MPa) to increase the solubility of hydrogen in bio-oil and the reaction rate. The upgrading process proposed in the present invention relies on electrochemical reactions for hydrogenation, does not require the introduction of high-pressure hydrogen, and can be operated under atmospheric or low-pressure conditions. This not only reduces the need for complex pressurized equipment but also improves the operating safety. In addition, the mildness of the reaction conditions is also reflected in that when using SOEC for hydrogenation upgrading, the reaction voltage can be precisely controlled by an external electrochemical workstation. This high degree of controllability allows the reaction to carry out hydrogenation and deoxygenation under controllable energy requirements, avoiding the problem of overreaction, thus reducing unnecessary side reactions, especially avoiding side reactions such as coking or cracking. Since the SOEC electrochemical reaction mainly relies on the action of solid electrolytes and electrode materials, it does not require complex chemical catalysts, nor does it require the process of catalyst regeneration or replacement. This is different from the expensive and operation-condition-sensitive metal catalysts required for traditional hydrocracking, greatly simplifying the operating conditions and structural devices of the system.

[0106] The above shows and describes the basic process, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A biomass pyrolysis steam integrated coupling online upgrading system based on SOEC, the system comprising a steam generator (1), SOEC (5), an electrochemical workstation (9), and a fast pyrolysis furnace (11), wherein the SOEC (5) is a sandwich structure, which is composed of an air electrode, an electrolyte, and a fuel electrode from top to bottom, and is characterized in that: The SOEC (5) is fixed in the heating furnace (6) via a hollow reaction tube (7); an air inlet pipe a (4) is provided above the air electrode of the SOEC (5) to connect with the steam generator (1); a feed pipe b (8) is provided below the fuel electrode of the SOEC (5) to connect with the fast pyrolysis furnace (11) and the air pump (12); the feed pipe b (8) is located inside the hollow reaction tube (7) to form a double-layer reaction channel; The water vapor generated by the steam generator (1) is electrolyzed on the air electrode surface of the SOEC (5) to generate H, and enters the fuel electrode side to react with the gas from the fast pyrolysis furnace (11) after pyrolysis of biomass to produce gas-solid phase electrochemical hydrogenation and upgrading reaction. The resulting reaction product flow moves in the same chamber of the double-layer reaction channel in a countercurrent manner, thereby forming a continuous stirred tank reactor condition, and realizing online deep hydrogenation and upgrading of bio-oil; The air electrode and the fuel electrode are respectively connected to an electrochemical workstation (9), and the voltage applied by the electrochemical workstation (9) to the SOEC (5) satisfies the following thermodynamic and kinetic relationships: , ΔG is the Gibbs free energy of the reaction, n is the number of electrons transferred, F is the Faraday constant, and E is the cell voltage; The relationship between the residence time and flow rate of the air inlet pipe a (4) and the feed pipe b (8) entering the hollow reaction tube (7) follows the following formula: , V is the effective volume of the reactor and Q is the volume flow rate of the inlet gas / feed.

2. According to claim 1, a biomass pyrolysis steam integrated coupling online upgrading system based on SOEC is characterized in that: The steam generator (1) is connected to the air electrode of the SOEC (5) through an air inlet pipe a (4) wrapped by a heating pipe a (3); the lower end of the air inlet pipe a (4) is 1.0-1.5 cm away from the air electrode of the SOEC (5).

3. The SOEC-based biomass pyrolysis steam integrated coupling online upgrading system according to claim 1 is characterized in that: The fast pyrolysis furnace (11) directly enters the fuel electrode of the SOEC through a feed pipe b (8) wrapped by a heating pipe b (10); the upper end of the feed pipe b (8) is 0.5-1.0 cm away from the fuel electrode of the SOEC; the length of the preheating section of the feed pipe b (8) in the heating furnace (6) is 30-40 cm; The fast pyrolysis furnace (11) is connected in parallel with an air pump (12), and air is continuously pumped into the feed pipe b (8) through the air pump (12), thereby driving the pyrolysis gas to the fuel electrode of the SOEC.

4. The SOEC-based biomass pyrolysis steam integrated coupling online upgrading system according to claim 1 is characterized in that: The feed pipe b (8) is located inside the hollow reaction tube (7), and the pipe diameter ratio of the feed pipe b (8) to the hollow reaction tube (7) is 1:(2-3), so as to ensure that the reaction product flow moves in the same chamber of the double-layer reaction channel in a countercurrent manner.

5. The SOEC-based biomass pyrolysis steam integrated coupling online upgrading system according to claim 1, characterized in that: The hydrodeoxygenation product is output to the cooling system (15) through the discharge pipe (14) wrapped by the heating pipe c (13), and the gas phase product is collected by the gas bag (16).

6. A biomass pyrolysis steam integrated coupled online upgrading process based on SOEC using the system as described in any one of claims 1 to 5, characterized in that: The following steps are involved: S1: The steam generated by the steam generator (1) is introduced into the air electrode of the SOEC (5) at a flow rate of 80-90 mL / min and a temperature of 200-250 °C; S2: The heating furnace (6) heats the SOEC (5) to 600-700 °C at a heating rate of 5-8 °C / min; S3: The electrochemical workstation (9) applies a constant voltage to the SOEC (5), and the voltage is maintained at 1.3-1.4 V, so that the SOEC (5) starts the electrolysis mode, and a large amount of H is produced from the fuel electrode at the lower end of the SOEC (5); S4: After the biomass feedstock is pyrolyzed in the fast pyrolysis furnace (11), it directly enters the fuel electrode of the SOEC through the feed pipe b (8); S5: At the same time, the air pump (12) is controlled to pump air into the feed pipe b (8) at a flow rate of 50-60 mL / min, driving the pyrolysis gas to the fuel electrode of the SOEC; S6: The feed stream input through the feed pipe b (8) flows perpendicularly to the fuel electrode area, and the pyrolysis gas undergoes a gas-solid phase electrochemical hydrogenation and upgrading reaction at the fuel electrode of the SOEC, and the resulting reaction product stream moves in a countercurrent manner in the same chamber, thereby forming a continuous stirred tank reactor condition; S7: The reaction product is transported from the discharge pipe (14) to the cooling system (15) to obtain a condensed liquid product; S8: The non-condensable gas is collected by the gas bag (16).

7. The SOEC-based biomass pyrolysis steam integrated coupling online upgrading process according to claim 6 is characterized in that: Step S1: the water content of the water vapor generated by the steam generator (1) is 3%-10%; The flow rate of water vapor is controlled by a mass flow meter (2), and the temperature of water vapor is controlled by heating an air inlet pipe a (4) through a heating pipe a (3).

8. The SOEC-based biomass pyrolysis steam integrated coupling online upgrading process according to claim 6 is characterized in that: Step S4: the pyrolysis conditions of the fast pyrolysis furnace (11) are: heating at a rate greater than 10000°C / s to 500-600°C and staying there for 1s to complete the fast pyrolysis; Biomass raw materials include wood processing residues, forestry logging residues or crop straw agricultural residues; In step S4, the temperature of the heating pipe b (10) wrapped outside the feed pipe b (8) is 300-350°C to prevent condensation. Before the reaction, the fast pyrolysis furnace (11) needs to be purged with nitrogen at a rate of 0.2 L / h for 0.5 h at room temperature.

9. The SOEC-based biomass pyrolysis steam integrated coupling online upgrading process according to claim 6, characterized in that: The discharge pipe (14) in step S7 is heated by the heating pipe c (13) at a heating temperature of 120-150°C; The temperature of the cooling system (15) is controlled at -5-1°C.

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