Method for continuous catalytic hydrogenation modification of crude bio-oil

Abstract

The invention discloses a method for continuous catalytic hydrogenation modification of crude bio-oil, and belongs to the technical field of new energy, and the method comprises the following steps: mixing straw hydrothermal liquefied oil and an n-hexane solvent according to mass, adding a Pt / C catalyst, carrying out primary hydrogenation modification in a reducing atmosphere, cooling after reaction, and carrying out centrifugal separation to obtain light oil; and mixing the light oil with a Pt / C catalyst, carrying out secondary hydro-upgrading in a reducing atmosphere, and carrying out centrifugal separation after the reaction to obtain a supernatant, namely the trace sulfur-containing bio-oil. According to the present invention, with the synergistic effect of the combination of the staged hydrogenation process and the Pt / C catalyst, the carbon deposition generation and the catalyst deactivation are effectively inhibited, the sulfur content is significantly reduced, the problems of easy catalyst poisoning and poor product quality in the bio-oil modification process are solved, and the obtained bio-oil has characteristics of high fluidity and low sulfur content, and can be directly used as the clean fuel.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy and relates to a method for continuously catalytically hydrogenating and reforming crude bio-oil. Background Art

[0002] The non-renewable nature of fossil fuels and the environmental problems they cause during their use, such as greenhouse gas emissions and air pollution, have aroused people's strong interest in renewable alternative energy sources. In particular, the proposal of the "dual carbon" goal has increased the urgency and necessity of exploring renewable and pollution-free energy raw materials. Biomass, especially lignocellulosic biomass, such as wood and straw, exists in large quantities in nature, and has the characteristics of carbon neutrality during use, making it the most potential renewable alternative energy raw material. Bio-oil generated by thermochemical conversion of biomass under certain conditions is currently the only carbon-based liquid renewable alternative fuel. At present, there are two different thermochemical conversion methods to obtain bio-oil, namely pyrolysis and hydrothermal liquefaction. The difference is that the bio-oil obtained by pyrolysis contains significantly higher elements such as carbon and hydrogen. However, the pyrolysis method requires dehydration of the biomass, which will consume a lot of energy. Although the bio-oil obtained by the hydrothermal liquefaction method has a slightly lower calorific value, it does not require too much energy to remove the water from the biomass.

[0003] At present, the technology of converting straw biomass with high water content into bio-oil through hydrothermal liquefaction is relatively mature. However, due to the low-quality characteristics of the bio-oil, such as high oxygen content, high water content, low pH value, high viscosity and poor fluidity, complex composition and many impurities, and low calorific value, it is difficult to be widely used on a large scale. Therefore, the bio-oil obtained by hydrothermal liquefaction needs to be modified to obtain high-quality liquid fuel.

[0004] However, in the process of catalytic reforming of bio-oil produced by hydrothermal liquefaction, phenols and aldehydes contained in bio-oil are prone to form carbon deposits. When carbon deposits cover the surface and pores of the catalyst, the active sites on the catalyst will be blocked and deactivated, which will not only reduce the activity of the catalyst, but also lead to more carbon deposits. In addition, nitrogen-containing and sulfur-containing heterocyclic compounds in bio-oil and their removal products (NH, HS, etc.) are also prone to cause catalyst "poisoning" and deactivation, which in turn promotes the generation of carbon deposits, resulting in poor catalytic hydrogenation reforming of bio-oil. Therefore, in the process of bio-oil reforming, the problem of catalyst deactivation is often faced, which hinders the high-value utilization of bio-oil. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art that the bio-oil prepared by the hydrothermal method has high phenolic and nitrogen and sulfur contents resulting in poor catalytic hydrogenation and upgrading effect, the purpose of the present invention is to provide a method for continuous catalytic hydrogenation and upgrading of crude bio-oil.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: The method for continuous catalytic hydrogenation and reforming of crude bio-oil disclosed in the present invention comprises: mixing hydrothermal liquefied oil of straw prepared by taking straw as raw material with an organic solvent, adding a Pt / C catalyst for a first hydrogenation reforming, cooling and separating after the reaction is completed to obtain light oil; mixing the light oil with the Pt / C catalyst, carrying out a second hydrogenation reforming, cooling and separating after the reaction is completed to obtain trace sulfur-containing bio-oil.

[0007] Preferably, the above method for continuous catalytic hydrogenation and upgrading of crude bio-oil comprises the following steps: 1) Preparation of straw hydrothermal liquefied oil: Mix straw powder with water, increase temperature and pressure in an inert atmosphere, and perform a hydrothermal reaction to obtain straw hydrothermal liquefied oil; 2) First hydrogenation reforming: adding an organic solvent and a Pt / C catalyst to the straw hydrothermal liquefied oil, heating and heat preservation in a reducing atmosphere after mixing to perform catalytic hydrogenation, quenching the reaction to obtain a reaction gas, a layered upper layer oil and a lower layer oil; further centrifuging the upper layer oil to separate the upper layer oil into an upper layer liquid and a lower layer liquid, and separating the upper layer liquid to obtain the light oil; 3) Second hydrogenation reforming: Pt / C catalyst is added to the light oil, and the oil is heated and kept warm in a reducing atmosphere for catalytic hydrogenation. After quenching the reaction, reaction gas and product liquid are obtained, and the product liquid is centrifuged to separate the supernatant to obtain the trace sulfur-containing bio-oil.

[0008] More preferably, the organic solvent is n-hexane.

[0009] Further preferably, the first hydro-reforming reaction is carried out at 300-400° C. for 1.5-2.5 h, the reaction pressure is 13-20 MPa, and the rotation speed of the centrifugal treatment of the upper layer oil is 12000 rpm.

[0010] Further preferably, the mass ratio of the straw hydrothermal liquefaction oil to the organic solvent in the first hydrogenation reforming is 1:(1-3).

[0011] Further preferably, in the first hydro-reforming, the ratio of the straw hydrothermal liquefaction oil to the Pt / C catalyst is 10:1; in the second hydro-reforming, the ratio of the light oil to the Pt / C catalyst is 10:1; and the mass fraction of the Pt / C catalyst is 5%.

[0012] Further preferably, in the second hydrogenation reforming, the reaction temperature is 350°C to 450°C, the reaction time is 1.5h to 2.5h, and the reaction pressure is 12 MPa to 14 MPa.

[0013] Further preferably, the reducing atmosphere hydrogen supply agent used in the first hydro-upgrading and the second hydro-upgrading is hydrogen.

[0014] Further preferably, the straw is selected from corn straw, soybean straw, peanut straw or rice straw.

[0015] More preferably, the sulfur content of the prepared trace sulfur-containing bio-oil is less than 1 ppm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: The method for continuous catalytic hydrogenation and reforming of crude bio-oil disclosed in the present invention comprises mixing hydrothermal bio-oil prepared by a hydrothermal method with an organic solvent, and using Pt / C for catalytic hydrogenation in a supercritical state of the organic solvent to reduce the viscosity of the system, and participating in hydrogenation and other reactions as a solvent to increase the reaction rate, and synergizing with the Pt / C catalyst to increase the mass transfer rate and catalyst life, thereby achieving the first step of catalytic hydrogenation of straw crude bio-oil. The present invention systematically solves the core problems of catalyst deactivation, incomplete impurity removal, and low product quality in bio-oil reforming through a staged hydrogenation and solvent synergistic strategy. The graded hydrogenation design is conducive to separating the deoxygenation and desulfurization / nitrogenation steps, and reducing the single catalyst load. An organic solvent is selected to assist in mass transfer, and the catalytic hydrogenation reaction rate is increased in a supercritical state. Furthermore, by controlling the temperature, pressure and other parameters of the first and second hydrogenation reforming, the optimized combination balances the reaction kinetics and thermodynamics.

[0017] The method proposed in the present invention also adopts the synergistic effect of Pt / C catalyst in the second hydrogenation reforming through a staged hydrogenation process, effectively inhibits carbon deposition and catalyst deactivation, significantly reduces the sulfur content, and solves the problems of catalyst poisoning and poor product quality during the bio-oil reforming process. The obtained bio-oil has the characteristics of high fluidity and low sulfur content, and can be directly used as a clean fuel, ultimately achieving a bio-oil sulfur content of less than 1ppm, improved fluidity, and increased calorific value, providing a feasible industrialization path for bio-oil to replace fossil fuels. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the distribution diagram of the first hydrogenation product of the embodiment of the present invention; Figure 2 A graph showing the distribution of trace sulfur bio-oil products prepared in accordance with an embodiment of the present invention; Figure 3 This is a morphological photograph of the trace sulfur bio-oil prepared in an embodiment of the present invention; Figure 4 The content of N and S in the trace sulfur bio-oil prepared in the embodiment of the present invention; Figure 5 This is a graph showing the change in N content before the first hydro-upgrading and after the second hydro-upgrading in an embodiment of the present invention; Figure 6 This is the total ion current bubble diagram of the two-dimensional gas mass before and after hydrogenation and upgrading of Example 3 of the present invention; Figure 7 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0019] In order to enable people in the technical field to better understand the scheme of the present invention, the technical scheme in the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiment of the present invention. Obviously, the described embodiment is only a part of the embodiment of the present invention, not all the embodiments. Based on the embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0020] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0021] At present, hydrothermal liquefaction technology can relatively maturely convert high-moisture straw biomass into bio-oil. However, the product bio-oil has significant quality defects, including high oxygen content, high moisture content, low pH value, poor fluidity caused by high viscosity, coexistence of complex components and impurities, and low calorific value. These characteristics make it difficult to meet industrial fuel standards, which seriously restricts the large-scale promotion and application of this technology. Therefore, upgrading the quality of hydrothermal liquefied bio-oil is the only way to obtain high-quality liquid fuel.

[0022] During the catalytic modification process, the characteristics of bio-oil pose a dual challenge to the stability of the catalyst: first, phenolic and aldehyde components are very likely to undergo polycondensation reactions under reaction conditions to generate carbon deposits. These carbonaceous deposits not only cover the active sites on the catalyst surface, but also block the pore structure, resulting in rapid deactivation of the catalyst. It is worth noting that this deactivation process has a self-accelerating effect - the reduction of active sites will change the reaction path, but will aggravate the formation of carbon deposits. Secondly, the byproducts such as NH3 and H2S produced by the nitrogen- and sulfur-containing heterocyclic compounds in bio-oil during the hydrogenation process will undergo strong chemical adsorption with the metal components of the catalyst, resulting in irreversible "poisoning" deactivation. These two types of deactivation mechanisms not only act alone, but also produce synergistic effects: acidic poisoning sites may become new carbon nucleation centers, while carbon deposit coverage areas will change the flow direction of the reactants and aggravate local poisoning. This complex catalyst deactivation problem significantly reduces the efficiency and economy of the modification process, leading to problems such as product quality fluctuations and frequent catalyst replacement, and has become a core technical bottleneck restricting the high-value utilization of bio-oil.

[0023] To solve this problem, the present invention uses soybean straw, peanut straw, corn straw, rice straw and other types of biomass as raw materials, obtains crude bio-oil through hydrothermal liquefaction technology, first uses Pt / C as a catalyst, n-hexane and an external hydrogen source as a hydrogen donor to catalytically hydrodesulfurize the crude bio-oil, and then separates the obtained primary reformed oil into two parts of light and heavy components by centrifugation to separate the primary reformed oil, i.e., light oil. Then, Pt / C is used as a catalyst to continue catalytically hydrodesulfurizing the light oil to obtain a reformed oil fuel containing trace sulfur (<1ppm).

[0024] The present invention is further described in detail below in conjunction with the accompanying drawings: Figure 7 The process flow chart of the present invention is as follows. The present invention uses Pt / C as a catalyst, n-hexane and an external hydrogen source as hydrogen donors, catalytically hydrodesulfurizes crude bio-oil, and separates the obtained primary reformed oil by centrifugation into two components, light and heavy.

[0025] The method comprises the following steps: mixing the straw hydrothermal liquefied oil prepared from straw as raw material with an organic solvent, adding a Pt / C catalyst for the first hydrogenation reforming, cooling and separating after the reaction to obtain light oil; mixing the light oil with the Pt / C catalyst, performing the second hydrogenation reforming, cooling and separating after the reaction to obtain trace sulfur-containing bio-oil. Specifically, the method comprises the following steps: 1) Preparation of straw hydrothermal liquefied oil: Mix straw powder with water, increase temperature and pressure in an inert atmosphere, and perform hydrothermal reaction to obtain straw hydrothermal liquefied oil; the method of the present invention has a wide adaptability to raw materials and can promote the hydrolysis and pyrolysis of various straw biomaterials such as cellulose and lignin.

[0026] 2) First hydrogenation reforming: adding an organic solvent and a Pt / C catalyst to the straw hydrothermal liquefied oil, heating and heat preservation in a reducing atmosphere after mixing to perform catalytic hydrogenation, quenching the reaction to obtain a reaction gas, a layered upper layer oil and a lower layer oil; further centrifuging the upper layer oil to separate the upper layer oil into an upper layer liquid and a lower layer liquid, and separating the upper layer liquid to obtain the light oil; Mixing organic solvent with straw hydrothermal liquefaction oil can reduce the viscosity of bio-oil, improve fluidity, and prevent coking on the catalyst surface. Pt / C catalyst preferentially removes oxygen-containing functional groups (such as hydroxyl and carboxyl) under H2 atmosphere, reduces the acid value (pH increase) and oxygen content of bio-oil, increases calorific value, selectively hydrogenates saturated double bonds, and reduces subsequent carbon deposition precursors (such as phenols and aldehydes). High-speed centrifugation (12000 rpm) quickly separates light oil and heavy components (coke, unreacted solids) to avoid heavy components clogging subsequent catalysts.

[0027] 3) Second hydrogenation reforming: Pt / C catalyst is added to the light oil, and the oil is heated and kept warm in a reducing atmosphere for catalytic hydrogenation. After quenching the reaction, reaction gas and product liquid are obtained, and the product liquid is centrifuged to separate the supernatant to obtain the trace sulfur-containing bio-oil.

[0028] This step is hydrogenated at a higher temperature. Higher temperatures promote the breaking of C-S and C-N bonds of heterocyclic sulfur / nitrogen compounds (such as thiophene and pyrrole), generating H2S and NH3, which are then removed. Pt / C catalysts have high adsorption activity for sulfides. H2S is generated and released through hydrogenation to reduce the sulfur content to below 1 ppm. Staged hydrogenation reduces the concentration of sulfur / nitrogen poisons in a single reaction and reduces the risk of catalyst poisoning. The first reforming has removed some carbon precursors (phenolic aldehydes) and reduced carbon formation in the second reaction. The second hydrogenation further saturates aromatics, reduces viscosity, improves fluidity, and makes bio-oil closer to traditional fuel properties.

[0029] In this method, the organic solvent is n-hexane. The present invention uses n-hexane to mix with straw hydrothermal liquefied oil in the first hydro-reforming, which can dilute the macromolecular carbon-depositing substances in the straw hydrothermal liquefied oil, which can greatly alleviate catalyst poisoning and inhibit the formation of carbon deposition. The nitrogen and sulfur content in the modified oil prepared by the second hydro-reforming also shows a significant decrease, and its sulfur content is effective at 1ppm. With the increase of the n-hexane addition ratio, the content of light components in the first modified oil can be significantly improved. When the mass ratio of n-hexane to crude bio-oil is 3:1, the light component yield is up to 78.54wt.%. The present invention uses n-hexane as a solvent before hydro-reforming and adds it to the bio-oil, which can not only dilute the asphaltene content in the bio-oil, but also increase the fluidity and heat and mass transfer performance of the bio-oil, so that the adhesion of the asphaltene component on the catalyst surface can be effectively avoided during the catalytic hydrogenation process, thereby alleviating catalyst poisoning and inhibiting the formation of carbon deposition, and improving the efficiency of biomass energy conversion.

[0030] The first hydrogenation reforming of this method is to heat the reactor to 300~400℃ for 1.5~2.5h, the optimal temperature is 350℃, the optimal reaction time is 2h, and the reaction pressure is 13~20MPa. When the upper oil is centrifuged to separate the light oil, the optimal speed of the centrifuge is 12000 rpm.

[0031] In the first hydrogenation reforming process of the present method, the mass ratio of the straw hydrothermal liquefaction oil to the organic solvent is 1:(1-3).

[0032] In the first hydrogenation reforming process of the method, the usage ratio of the straw hydrothermal liquefaction oil to the Pt / C catalyst is 10:1.

[0033] In the first hydrogenation and reforming process, in addition to the upper oil, the lower viscous liquid heavy oil and residue are also produced. The residue remaining after the upper oil is centrifuged to separate the light oil is mixed with the heavy oil and residue before centrifugation, washed and filtered with dichloromethane, and dried to obtain a solid product. The solvent is evaporated from the filtrate, and the remaining substance is the heavy oil product.

[0034] In the second hydro-reforming process of the method, the usage ratio of light oil to Pt / C catalyst is 10:1; the mass fraction of Pt / C catalyst used in the first hydro-reforming and the second hydro-reforming is 5%.

[0035] During the second hydrogenation reforming process of the present method, the reaction temperature is 350-450°C, the optimum reaction temperature is 400°C, the reaction time is 1.5-2.5h, the optimum reaction time is 2h, and the reaction pressure is 12-14 MPa.

[0036] Gas is produced during the second hydrogenation and reforming. After the reformed oil is separated, the remaining residue is washed and filtered with dichloromethane and dried to obtain a solid residue which is weighed to calculate the reformed oil yield.

[0037] The solid products, heavy oil products, gas, etc. produced in the process can be weighed and the modified oil yield can be calculated using the subtraction method.

[0038] The reducing atmosphere used in the first hydrogenation and the second hydrogenation in this method is hydrogen.

[0039] The biomass raw material of the method is selected from corn straw, soybean straw, peanut straw or rice straw.

[0040] The sulfur content of the trace sulfur-containing bio-oil prepared by the method is less than 1 ppm.

[0041] The following is a specific description with reference to the embodiments: Example 1 1) Preparation of hydrothermal liquefied oil 150 g of dried and crushed soybean straw powder and 400 mL of deionized water were added to a 1 L stainless steel high-pressure reactor and stirred evenly, and then sealed. Helium was used to exhaust the air in the reactor for 15 min. The reactor was placed in a heating jacket and the temperature was raised. The heating time of the reactor was about 100 min, the speed of the stirrer was about 600 rpm, and the reaction time was maintained for 1 h after the temperature rose to 320 °C. The pressure during the reaction was about 12 MPa.

[0042] After the reaction is completed, the reactor is lifted out and placed in water to cool to room temperature. Then the reactor is taken out of the water, blown dry and left to stand. After cooling, the pressure in the reactor is about 2 MPa.

[0043] After exhausting, open the reactor, pour out the reaction liquid in the reactor, and rinse the reactor wall with dichloromethane to dissolve the oil adhering to the reactor wall in dichloromethane, and then pour it out together with the residue and combine it with the reaction liquid. The reaction liquid is filtered and rotary evaporated in turn to obtain soybean straw hydrothermal liquefaction oil.

[0044] 2) First hydrogenation reforming of straw hydrothermal liquefied oil Hydrogenation reforming of liquefied oil in supercritical n-hexane Take 5 g of crude bio-oil from straw hydrothermal liquefaction and add it to a 50 mL reactor, add 5 g of n-hexane, add 0.5 g of 5wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPaH2 and tighten the valve. Put it in a salt bath that has been heated to 350 ℃. After about 20 min, the reactor is heated to 350 ℃ and the timing is started. The reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction. After cooling to room temperature, take it out and blow dry. The pressure in the reactor drops to 3~4 MPa. Weigh the mass of the reactor, open the outlet valve to deflate, weigh the mass of the reactor after deflation, and the difference in mass before and after is the mass of the gas produced by the reaction.

[0045] Open the reactor, the upper layer is a liquid with good fluidity (called the upper oil), and the lower layer is a viscous liquid heavy oil and residue. Transfer the upper oil to a 50 mL centrifuge tube, the centrifuge speed is 12000 rpm, and the upper liquid after centrifugation is the light oil.

[0046] Pour out the upper liquid and weigh it, which is the mass of the light oil. Combine the remaining small amount of residue with the heavy oil and residue in the reactor, add about 20 mL of dichloromethane to wash, transfer to a Buchner funnel for suction filtration, and use about 50 mL of dichloromethane to wash the residue while suction filtration three times. The solid residue is placed in a 105 ℃ oven and dried to constant weight, and the mass is the solid mass. The filtrate is rotary evaporated from the solvent in a 100mL round-bottom flask. The water bath temperature of the rotary evaporation is 35 ℃, the rotation speed is 60 rpm, and the evaporation is until the vacuum degree is 0.09 MPa. Stop the rotary evaporation, take out the flask and blow dry. Weigh the mass, and the difference between the mass of the flask after rotary evaporation and the mass of the empty flask is the mass of the heavy oil.

[0047] 3) Secondary hydrogenation reforming of light oil Take 2 g of light oil and 0.2 g of 5 wt.% Pt / C catalyst and add them to a 10 mL reactor, which is sealed. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Start timing when the reactor is heated to 400°C, the reaction time is 2 h, and the pressure rises to 12~14 MPa during the reaction. After 2 h, put the reactor into water to cool and quench the reaction. After cooling to room temperature, take it out and blow dry, and the pressure drops to 4~5 MPa.

[0048] Weigh the mass of the reactor, open the outlet valve to release the gas, weigh the mass of the reactor after release, and the difference between the mass before and after is the mass of the gas produced by the reaction. Open the reactor and try to transfer the liquid and solid in the reactor to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The supernatant is the prepared modified oil. Pour out the supernatant and seal it for storage.

[0049] The remaining residue was washed out with a small amount of dichloromethane and filtered naturally. The filter residue was placed in a 105°C oven and dried to constant weight, which was the mass of the solid residue.

[0050] Example 2 1) Hydrothermal liquefaction oil was prepared using soybean straw powder, and the preparation process was the same as that in Example 1.

[0051] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 10 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0052] 3) The second hydrogenation process is the same as in Example 1.

[0053] Example 3 1) Hydrothermal liquefaction oil was prepared using soybean straw powder, and the preparation process was the same as that in Example 1.

[0054] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 15 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0055] 3) The second hydrogenation process is the same as in Example 1.

[0056] Example 4 1) Corn straw hydrothermal liquefaction oil was prepared using corn straw powder, and the preparation process was the same as that in Example 1.

[0057] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 5 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0058] 3) The second hydrogenation process is the same as in Example 1.

[0059] Example 5 1) Hydrothermal liquefaction oil was prepared using corn stalk powder, and the preparation process was the same as that in Example 1.

[0060] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 10 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0061] 3) The second hydrogenation process is the same as in Example 1.

[0062] Example 6 1) Hydrothermal liquefaction oil was prepared using corn stalk powder, and the preparation process was the same as that in Example 1.

[0063] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 15 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0064] 3) The second hydrogenation process is the same as in Example 1.

[0065] Example 7 1) Peanut straw powder was used to prepare hydrothermal liquefied oil, and the preparation process was the same as that in Example 1.

[0066] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 5 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0067] 3) The second hydrogenation process is the same as in Example 1.

[0068] Example 8 1) Peanut straw powder was used to prepare hydrothermal liquefied oil, and the preparation process was the same as that in Example 1.

[0069] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 10 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0070] 3) The second hydrogenation process is the same as in Example 1.

[0071] Example 9 1) Peanut straw powder was used to prepare hydrothermal liquefied oil, and the preparation process was the same as that in Example 1.

[0072] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 15 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0073] 3) The second hydrogenation process is the same as in Example 1.

[0074] Example 10 1) Hydrothermal liquefaction oil was prepared using rice straw powder, and the preparation process was the same as that in Example 1.

[0075] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 5 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0076] 3) The second hydrogenation process is the same as in Example 1.

[0077] Embodiment 11 1) Hydrothermal liquefaction oil was prepared using rice straw powder, and the preparation process was the same as that in Example 1.

[0078] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 10 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0079] 3) The second hydrogenation process is the same as in Example 1.

[0080] Example 12 1) Hydrothermal liquefaction oil was prepared using rice straw powder, and the preparation process was the same as that in Example 1.

[0081] 2) First hydrogenation reforming: Take 5 g of straw hydrothermal liquefaction crude bio-oil and add it to a 50 mL reactor, add 15 g of n-hexane, add 0.5 g of 5 wt.% Pt / C catalyst and mix, and seal the reactor. Replace the air in the reactor with H2 for about 15 min, then fill the reactor with 6 MPa H2 and tighten the valve. Heat the reactor to 350 °C, start timing, the reaction time is 2 h, and the pressure during the reaction is about 14~19 MPa. Put the reactor into water to cool and quench the reaction, and take it out and blow dry after cooling to room temperature. Open the reactor and transfer the upper layer of oil to a 50 mL centrifuge tube. The centrifuge speed is 12000 rpm. The upper layer of liquid after centrifugation is light oil.

[0082] 3) The second hydrogenation process is the same as in Example 1.

[0083] Effect example Figure 1 The distribution of modified products of bio-oils obtained from four crop straws through hydrothermal liquefaction under different n-hexane addition amounts. Taking peanut straw as an example, when it is directly modified without adding n-hexane, the yield of modified oil (not distinguishing between light oil and heavy oil) is 47.93 wt.%, and after adding n-hexane, when the mass ratio of bio-oil to n-hexane increases from 1:1 to 1:3, its light oil yield increases from 57.62 wt.% to 77.24 wt.%, and the total yield of modified oil (including light oil and heavy oil) increases from 76.37 wt.% to 82.54 wt.%. And when the mass ratio of bio-oil to n-hexane is 1:2, its solid yield also drops sharply to 6.84 wt.%, which is much lower than the value (29.76 wt.%) when peanut straw bio-oil is directly hydrogenated. This shows that n-hexane as a solvent plays a very obvious role in inhibiting carbon deposition and alleviating catalyst poisoning in the catalytic hydrogenation of straw bio-oil.

[0084] The product distribution of Example 2, Example 5, Example 8 and Example 11 is as follows Figure 2 As shown, it can be seen that the yield of the modified oil exceeds 92 wt.%, and the modified oil is transparent and clear with excellent fluidity. Figure 3 , and the solid yield dropped below 1wt.%, which also shows the necessity of adding n-hexane in the primary hydrogenation reforming.

[0085] Figure 4The N and S contents of four crop straw modified oils at different n-hexane addition amounts are listed. It can be seen that in general, the N and S contents decrease in an orderly manner with the increase in the amount of n-hexane added. When the mass ratio of bio-oil to n-hexane is 1:2, the lowest N content in the modified oil (soybean straw) has dropped to below 900 ppm, and the S content has mostly dropped to tens of ppm, which is very close to the value of national standard 6 (<10 ppm). After the secondary modification of its light oil, its N content dropped to a minimum of 26 ppm (soybean straw) and a maximum of only 503 ppm (peanut straw) (see Figure 5 ), the S content of the four straw secondary reformed oils also dropped below the detection limit of the instrument (<1 ppm). Figure 5 Not listed. It can be seen that the addition of n-hexane during the bio-oil hydro-modification process can significantly improve the removal rate of heteroatoms in the modified oil without introducing new heteroatoms. The molecular composition and elemental composition of the four types of straw hydrothermal liquefaction oils before and after modification are shown in Tables 1 and 2.

[0086] Table 1 Molecular composition of four types of light oil before and after upgrading (% of peak area occupied by two-dimensional gas chromatography)

[0087] Table 2 Element composition (wt. %) and calorific value of light oil

[0088] Figure 6 Taking soybean straw as an example, after secondary reforming, the ketones and phenols in the light oil are almost completely converted into hydrocarbons, and the reformed oil is almost entirely hydrocarbons and aromatic hydrocarbons, with a calorific value of more than 47 MJ kg -1 , which is equivalent to the calorific value of commercially available gasoline and diesel.

[0089] The above contents are only for explaining the technical idea of ​​the present invention and cannot be used to limit the protection scope of the present invention. Any changes made on the basis of the technical solution in accordance with the technical idea proposed by the present invention shall fall within the protection scope of the claims of the present invention.

Claims

1. A method for continuously catalytically hydrogenating and upgrading crude bio-oil, characterized in that: include: The straw hydrothermal liquefaction oil prepared with straw as raw material is mixed with an organic solvent, and a Pt / C catalyst is added to perform the first hydrogenation reforming, and after the reaction is completed, it is cooled and separated to obtain light oil; the light oil is mixed with a Pt / C catalyst, and a second hydrogenation reforming is performed, and after the reaction is completed, it is cooled and separated to obtain modified oil, i.e., trace sulfur-containing bio-oil.

2. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 1, characterized in that: The following steps are involved: 1) Preparation of straw hydrothermal liquefied oil: Mix straw powder with water, increase temperature and pressure in an inert atmosphere, and perform a hydrothermal reaction to obtain straw hydrothermal liquefied oil; 2) First hydrogenation reforming: adding an organic solvent and a Pt / C catalyst to the straw hydrothermal liquefied oil, heating and heat preservation in a reducing atmosphere after mixing to perform catalytic hydrogenation, quenching the reaction to obtain a reaction gas, a layered upper layer oil and a lower layer oil; further centrifuging the upper layer oil to separate the upper layer oil into an upper layer liquid and a lower layer liquid, and separating the upper layer liquid to obtain the light oil; 3) Second hydrogenation reforming: Pt / C catalyst is added to the light oil, and the light oil is heated and kept warm in a reducing atmosphere for catalytic hydrogenation. After quenching the reaction, reaction gas and product liquid are obtained, and the product liquid is centrifuged to separate the supernatant to obtain the reformed oil.

3. The method for continuous catalytic hydro-upgrading of crude bio-oil according to claim 1 or 2, characterized in that: The organic solvent is n-hexane.

4. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 3, characterized in that: The first hydro-reforming reaction is carried out at 300-400°C for 1.5-2.5h, the reaction pressure is 13-20MPa, and the rotation speed of the centrifugal treatment of the upper layer oil is 12000 rpm.

5. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 1 or 2, characterized in that: The mass ratio of the straw hydrothermal liquefied oil to the organic solvent in the first hydrogenation reforming is 1:(1-3).

6. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 1 or 2, characterized in that: In the first hydro-reforming, the ratio of the straw hydrothermal liquefaction oil to the Pt / C catalyst is 10:1; in the second hydro-reforming, the ratio of the light oil to the Pt / C catalyst is 10:1; the mass fraction of the Pt / C catalyst is 5%.

7. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 2, characterized in that: In the second hydrogenation reforming, the reaction temperature is 350-450° C., the reaction time is 1.5-2.5 h, and the reaction pressure is 12-14 MPa.

8. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 2, characterized in that: The reducing atmosphere hydrogen supply agent used in the first hydro-upgrading and the second hydro-upgrading is hydrogen.

9. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 1 or 2, characterized in that: The straw is selected from corn straw, soybean straw, peanut straw or rice straw.

10. The method for continuous catalytic hydrogenation and upgrading of crude bio-oil according to claim 1 or 2, characterized in that: The sulfur content in the prepared modified oil is less than 1ppm.

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