A biomass liquefaction method

Abstract

A biomass liquefaction method comprises the following steps: (1) removing impurities from biomass, crushing and drying; (2) mixing biomass, solvent and catalyst in proportion, and pyrolyzing at 200-400°C and 0.1-3MPa under anaerobic hydrogen conditions; (3) performing solid-liquid-gas separation on the product to obtain liquid bio-oil, combustible gas and solid residue; the catalyst is partially carbonized activated carbon loaded with iron, and the iron content is 0.5-10wt% based on the total weight of the catalyst; the activated carbon is partially carbonized activated carbon, and the carbon content is 60-80wt% based on the activated carbon carrier. The biomass liquefaction method improves the catalyst and liquefaction process conditions, adopts a low-cost catalyst, and can be reused, reduces the difficulty of later separation and catalyst regeneration, thereby reducing the cost of biomass liquefaction and significantly improving the yield of hydrocarbons, especially cycloalkanes.

Description

Technical Field

[0001] The invention relates to a biomass liquefaction method, in particular to a method for preparing biomass oil by pyrolysis under hydrogen conditions using a partially carbonized activated carbon-loaded iron catalyst as a catalyst, and belongs to the field of renewable liquid fuel preparation. Background Art

[0002] Biomass oil is an oily substance containing various organic compounds such as alcohols, phenols, aldehydes, carboxylic acids, hydrocarbons, etc. obtained by physical and chemical reactions of biomass. Bio-oil has a wide range of sources, and sludge, forests, etc. can be prepared through specific means. Because its raw materials are renewable, bio-oil has the advantages of being green, environmentally friendly, and low-carbon, and is a clean energy source. The use of biomass oil realizes the resource conversion of renewable biomass, which can not only alleviate the current excessive dependence on non-renewable resources, but also realize the refined utilization of biomass energy and significantly reduce pollutant emissions. In the context of the era of "reducing carbon emissions", it has broad application and development prospects.

[0003] There are many technologies for biomass pyrolysis oil production, which can be divided into direct liquefaction and indirect liquefaction technology according to the liquefaction method. Biomass direct liquefaction technology uses a reactor as a reaction vessel, and biomass and solvents are directly liquefied at 200-400℃ and 5-25MPa to obtain organic small and medium-molecule substances. In order to obtain a higher oil yield, small molecule organic or inorganic solvents are generally used in this process. Indirect liquefaction technology actually generates water gas from biomass at high temperature, and then uses the Fischer-Tropsch reaction to synthesize hydrocarbon liquid oil products.

[0004] The direct liquefaction of biomass is essentially the breaking of weak covalent bonds of biomass to produce free radical fragments, which further react to obtain biomass oil products. In the process of biomass liquefaction conversion, the solvent and catalyst in the liquefaction reaction system are very important. First, the biomass forms a homogeneous reaction system with the catalyst and solvent, so that the biomass expands and increases the contact area with the catalyst, etc., which promotes its effective dispersion and degradation. In this system, the reaction substances can fit closely, stabilize and dissolve the liquefied products, and effectively inhibit the polymerization of the liquefied products. In many reaction processes, the solvent of the liquefaction reaction system has a certain promoting effect on mass transfer and heat transfer in the chemical reaction process, and can also exist in the system as a hydrogen donor to provide a hydrogen source for the liquefaction system. The choice of catalyst is also crucial. In the absence of a catalyst, the decomposition reaction of high molecular weight organic matter is mainly activated by heat, and depolymerization products are generated through the auxiliary mechanism of free radicals. The addition of a catalyst will reduce the activation energy of the reaction and rearrange the reaction path. Porous zeolite catalysts are the most commonly used catalysts. Their developed pore structure and acidic sites provide active sites for the reaction space. There are also reports on the use of metal-doped molecular sieve catalysts for biomass liquefaction. However, in the biomass liquefaction reaction, this catalyst is prone to ash deposition, the catalyst life is short, and regeneration is difficult.

[0005] As a renewable resource with great potential, biomass oil has a wide range of applications, including production of fuel oil or extraction of chemical products, gasification to generate synthesis gas, preparation of bio-asphalt, recycling of aged asphalt, use as a biomass solid fuel binder, and mixed refining with secondary processed heavy oil, etc. The market prospects are very broad.

[0006] CN106995733A discloses a method for preparing a biomass additive for improving diesel performance, comprising the following steps: 1) pretreatment of biomass raw materials: drying and pretreatment of biomass raw materials to obtain biomass fuel; 2) pyrolysis of biomass fuel: pyrolysis of the biomass fuel obtained in step 1) under anoxic conditions to obtain pyrolysis products containing water, gas, aqueous bio-oil and oil-phase bio-oil, and then collecting the aqueous bio-oil by static stratification; 3) esterification and upgrading of bio-oil: dewatering and filtering the aqueous bio-oil obtained in step 2) to obtain bio-oil, and then esterifying the bio-oil, and evaporating and condensing the short-chain esters generated by the reaction to obtain a short-chain ester solution, i.e., the biomass-based additive for improving diesel performance. The additive can be mixed with diesel in any proportion, saving the use of petroleum resources.

[0007] CN102057019A discloses a method for producing hydrocarbons from pyrolysis oil feedstock, comprising: bringing the pyrolysis oil into contact with a partial deoxygenation and hydrogenation catalyst under deoxygenation conditions in the presence of hydrogen, thereby partially deoxygenating the complete pyrolysis oil in a partial deoxygenation zone to produce a partially deoxygenated pyrolysis oil stream containing water, gas, light fractions and hydrocarbons; the partially deoxygenated pyrolysis oil flows into a separation zone, thereby separating the water, gas and light fraction streams from the hydrocarbon stream; the hydrocarbon stream flows into a complete deoxygenation zone, and bringing the hydrocarbon stream into contact with a deoxygenation catalyst under deoxygenation conditions to produce a product stream, wherein the product stream contains hydrocarbon compounds and can be used as a fuel or a mixed fuel component.

[0008] CN102712847A discloses a biomass refining method, comprising dehydrating and drying the biomass, producing crude oil by directly liquefying the dried biomass, hydrogenating the crude oil into hydrocarbons; and refining the hydrocarbons into petrochemical products, wherein the hydrogen used for the hydrogenation is obtained from wastewater produced by dehydration and / or direct liquefaction of the biomass and residues produced during direct liquefaction.

[0009] The current biomass liquefaction methods generally have the problem of large catalyst usage and high cost. Further research is needed to reduce the catalyst usage and cost of biomass liquefaction in order to promote the popularization and promotion of biomass liquefaction. Summary of the invention

[0010] Based on the problems of high biomass liquefaction cost and short catalyst life in the prior art, the present invention improves the catalyst and liquefaction process conditions, adopts a low-cost catalyst that can be reused, and reduces the difficulty of subsequent separation and catalyst regeneration.

[0011] Activated carbon is a common catalyst carrier in the chemical industry, and its impurity element content is controlled at a very low level. Generally speaking, the carbon content of conventional industrial activated carbon carriers is more than 90%, and the rest are elements such as oxygen, nitrogen, and hydrogen. Some catalyst carriers with higher requirements have a carbon content of even 95wt% or higher. The inventor unexpectedly found that partially carbonized activated carbon has better reactivity when used as a catalyst carrier for biomass liquefaction. Based on the above findings, the present invention uses partially carbonized activated carbon as a catalyst carrier, and uses ammonium liquid to carry out appropriate chemical modification, and is used in conjunction with iron. The catalyst carrier in the present invention has more polar sites such as hydroxyl and carbonyl compared to fully activated activated carbon, and partially preserves the natural pore structure formed in biomass, further improves the adsorption capacity of organic free radicals, is conducive to the catalytic active component iron further adjusting the direction of the liquefaction reaction, and obtains more hydrocarbon substances, especially improves the yield of cycloalkanes.

[0012] A biomass liquefaction method comprises the following steps: (1) removing impurities from biomass, crushing and drying; (2) mixing biomass, solvent and catalyst in proportion, and pyrolyzing them at 200-400°C and 0.1-3MPa under anaerobic conditions; (3) performing solid-liquid-gas separation on the product to obtain liquid bio-oil, combustible gas and solid residue; wherein the catalyst in step (2) is partially carbonized activated carbon loaded with iron, and the iron content is 0.5-10wt%, preferably 1-5wt%, and more preferably 1.5-2wt%, based on the total weight of the catalyst; and the activated carbon is partially carbonized activated carbon, and the carbon content is 60-80wt%, preferably 65-75wt%, and more preferably 70-73wt%, based on the activated carbon carrier.

[0013] The preparation method of the catalyst comprises the following steps: (a) partially carbonizing an activated carbon precursor; (b) chemically treating the partially carbonized activated carbon precursor obtained in step (a); (c) loading iron; and (d) calcining under an inert atmosphere. The partial carbonization in step (a) is carried out at 400-600°C for 5-30 min; preferably, the carbonization is carried out at 450-500°C for 10-15 min; the chemical treatment in step (b) is to immerse the partially carbonized activated carbon in an ammonium solution with a pH value of 9-11 for 1-12 h, and the molar concentration of ammonium ions in the ammonium solution is 1-3 mol / L; the molar concentration of iron ions in step (c) is 0.5-3 mol / L, and the immersion time is 1-12 h; the roasting treatment in step (d) is carried out in an inert atmosphere at 200-300°C for 5-30 min, and the inert atmosphere is carried out in a nitrogen atmosphere, and preferably, the inert atmosphere also includes 1-5% by volume of oxygen; the activated carbon precursor is a cellulose-rich biomass material, preferably one or more of crop straw, fungus residue, coconut shell, fallen leaves, corn cobs, and wood residues.

[0014] Preferably, the solid residue obtained in step (3) is used as a raw material for catalyst preparation.

[0015] Preferably, the combustible gas obtained in step (3) is used as fuel to provide heat for the pyrolysis reaction.

[0016] The biomass in step (1) is one or more of straw, waste oil, kitchen waste, and sewer sediment; the impurity removal is to remove impurities such as glass, metal, sand, etc. that cannot be decomposed in the biomass raw material; the pulverization is to pulverize and sieve the biomass to obtain particles with a particle size of 0.1-1 cm; the drying is carried out at 80-120° C. and a pressure of 0.01-0.1 MPa, preferably at a temperature of 90-100° C. and a pressure of 0.02-0.05 MPa.

[0017] The pyrolysis time in step (2) is 0.5-12h, preferably 1-6h, more preferably 2-3h; the pyrolysis temperature is preferably 250-350°C, more preferably 300-330°C; the pyrolysis pressure is preferably 0.5-2MPa, more preferably 1-1.5MPa; the mass ratio of biomass, solvent and catalyst in step (2) is 100:50-200:0.1-3, more preferably 100:80-100:0.5-1; the pyrolysis is carried out under an inert atmosphere, and the inert atmosphere is one of nitrogen and helium; preferably, hydrogen can also be added in step (2), and the hydrogen partial pressure is 0.1-0.5MPa, more preferably 0.2-0.5MPa.

[0018] The pyrolysis in step (2) is carried out in a reactor selected from the group consisting of a fluidized bed, a slurry bed, and a bubbling bed, preferably in a slurry bed.

[0019] The solvent in step (2) is one or more of biomass liquefied oil, coal tar, gasoline, diesel, kerosene, gas oil, and naphtha, more preferably biomass liquefied oil. The liquid bio-oil obtained in step (3) is preferably refluxed into the pyrolysis reactor as a solvent.

[0020] The catalyst in step (2) is partially carbonized activated carbon loaded with iron, and the iron content is 1-3wt%, more preferably 1.5-2wt%, based on the total weight of the catalyst; the activated carbon is partially carbonized activated carbon, and its carbon content is 70-80wt%, more preferably 73-76wt%, based on the activated carbon carrier.

[0021] The solid-liquid-gas separation in step (3) is carried out at 120-150°C, and the separated gas phase is preferably further cooled to separate the water therein; the bio-oil hydrocarbon yield is 20wt% or more, more preferably 25wt% or more, and the cycloalkane yield is 8wt% or more, more preferably 10wt% or more. The hydrocarbon yield is calculated by dividing the mass of hydrocarbon obtained by subtracting the mass of hydrocarbon in the corresponding solvent from the mass of the final hydrocarbon by the mass of the biomass in step (2); the cycloalkane yield is calculated by dividing the mass of cycloalkane obtained by subtracting the mass of cycloalkane in the corresponding solvent from the mass of the final cycloalkane by the mass of the biomass in step (2).

[0022] The beneficial technical effects of the present invention are as follows: the present invention uses low-cost partially carbonized activated carbon as a carrier to load metallic iron as a catalyst, and the solid residue after liquefaction can also be used as a source of catalyst carrier, which greatly reduces the cost of biomass liquefaction; the partially carbonized activated carbon carrier in the present invention has more hydroxyl and carbonyl active sites, which is easier to adsorb free radicals generated during pyrolysis and further decompose in a directed manner, thereby improving the yield of hydrocarbons. Implementation

[0023] In order to further illustrate the technical solution of the present invention, the following embodiments are provided, which are merely examples of the present invention and are not intended to limit the protection scope of the present invention. Example

[0024] Catalyst preparation

[0025] The method comprises the following steps: (a) using crop straw as an activated carbon precursor, crushing and sieving to a particle size of 0.1 cm after impurities are removed, and partially carbonizing the activated carbon precursor at 500° C. for 30 minutes; (b) activating the partially carbonized activated carbon precursor in an ammonia solution with a pH value of 9 for 6 hours; (c) immersing the activated carbon precursor in a solution with an iron ion concentration of 1 mol / L for 3 hours; and (d) calcining the activated carbon precursor at 200° C. for 5 minutes in an inert nitrogen atmosphere with an oxygen content of 1% by volume to obtain a catalyst a, wherein the carbon content of the carrier is 75% and the iron loading is 4wt%.

[0026] Biomass liquefaction method

[0027] The method comprises the following steps: (1) removing impurities from crop straw, drying it at 120°C and 0.01MPa, and crushing it to a particle size of 1 cm; (2) mixing the crushed and dried biomass, biomass liquefied oil and catalyst in a mass ratio of 100:50:1, and pyrolyzing them at 200°C and 3MPa under hydrogen conditions, wherein the hydrogen partial pressure is 0.5MPa; (3) performing solid-liquid-gas separation on the product at 120°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield in the separated liquid bio-oil is 21.3wt%, and the cycloalkane yield is 7.9wt%. Example

[0028] Catalyst preparation

[0029] The method comprises the following steps: (a) using pinewood residue as an activated carbon precursor, crushing and sieving the pinewood residue to a particle size of 0.5 cm after impurities removal, and partially carbonizing the pinewood residue at 400°C for 30 minutes; (b) activating the partially carbonized activated carbon precursor in an ammonium bicarbonate solution with a pH value of 10 for 4 hours; (c) immersing the pinewood residue in a solution with an iron ion concentration of 1 mol / L for 6 hours; and (d) calcining the pinewood residue at 300°C for 5 minutes in an inert nitrogen atmosphere with an oxygen content of 0.5% by volume to obtain a catalyst b, wherein the carbon content of the carrier is 69wt% and the iron loading is 6wt%.

[0030] Biomass liquefaction method

[0031] The method comprises the following steps: (1) drying the impurity-removed biomass at 110°C and 0.05MPa and crushing the biomass to a particle size of 0.5cm; (2) mixing the biomass, naphtha and catalyst in a mass ratio of 100:100:0.8, and pyrolyzing the biomass at 400°C and 2MPa under hydrogen conditions, wherein the hydrogen partial pressure is 1MPa; (3) performing solid-liquid-gas separation on the product at 100°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield in the separated liquid bio-oil is 24.9wt%, and the cycloalkane yield is 8.8%. Example

[0032] Catalyst preparation

[0033] The method comprises the following steps: (a) using corn cobs as activated carbon precursors, crushing and sieving them to a particle size of 0.3 cm after impurities removal, and carbonizing them at 550°C for 20 minutes for partial carbonization; (b) activating the partially carbonized activated carbon precursors in an ammonia solution with a pH value of 11 for 3 hours; (c) immersing them in a solution with an iron ion concentration of 1 mol / L for 2 hours; (d) calcining them at 300°C for 15 minutes in a nitrogen inert atmosphere with an oxygen content of 0.2% by volume. Catalyst c is obtained, wherein the carbon content of the carrier is 71% and the iron loading is 5wt%.

[0034] Biomass liquefaction method

[0035] The method comprises the following steps: (1) mixing crop straw and kitchen waste in a ratio of 1:1, drying at 120°C and 0.02MPa after impurities removal, and crushing to a particle size of 0.5 cm; (2) mixing biomass, solvent and catalyst in a mass ratio of 100:120:2, pyrolyzing at 400°C and 2MPa under hydrogen conditions, wherein the hydrogen partial pressure is 0.5MPa; (3) performing solid-liquid-gas separation on the product at 110°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield of the separated liquid bio-oil is 23.5wt%, and the cycloalkane yield is 9.4wt%.

[0036] Comparative Example 1

[0037] The same as Example 1, except that activated carbon with a carbon content of 95 wt% is used as the carrier.

[0038] Catalyst preparation

[0039] The method comprises the following steps: activating activated carbon with a carbon content of 95wt% in an ammonia solution with a pH value of 9 for 6h; immersing in a solution with an iron ion concentration of 1mol / L for 3h; and calcining in a nitrogen inert atmosphere with an oxygen content of 1vol% at 200°C for 5min to obtain a catalyst A with an iron loading of 4wt%.

[0040] Biomass liquefaction method

[0041] The method comprises the following steps: (1) drying the crop straw at 120°C and 0.01MPa after removing impurities, and crushing the crop straw to a particle size of 1 cm; (2) mixing the crushed and dried biomass, biomass liquefied oil and catalyst in a mass ratio of 100:50:1, and pyrolyzing the biomass at 200°C and 3MPa under hydrogen conditions, wherein the hydrogen partial pressure is 0.5MPa; (3) performing solid-liquid-gas separation on the product at 120°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield of the separated liquid bio-oil is 12.3wt%, wherein the cycloalkane yield is 1.4wt%.

[0042] Comparative Example 2

[0043] The same as Example 1, except that ZSM-5 molecular sieve is used as a carrier to load iron as a catalyst.

[0044] Catalyst preparation

[0045] The method comprises the following steps: activating the ZSM-5 molecular sieve in an ammonia solution with a pH value of 9 for 6 hours; immersing the ZSM-5 molecular sieve in a solution with an iron ion concentration of 1 mol / L for 3 hours; and calcining the ZSM-5 molecular sieve in an inert nitrogen atmosphere with an oxygen content of 1% by volume at 200° C. for 5 minutes to obtain a catalyst B with an iron loading of 4wt%.

[0046] Biomass liquefaction method

[0047] The method comprises the following steps: (1) removing impurities from crop straw, drying it at 120°C and 0.01MPa, and crushing it to a particle size of 1 cm; (2) mixing the crushed and dried biomass, biomass liquefied oil and catalyst in a mass ratio of 100:50:1, and pyrolyzing them at 200°C and 3MPa under hydrogen conditions, wherein the hydrogen partial pressure is 0.5MPa; (3) performing solid-liquid-gas separation on the product at 120°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield in the separated liquid bio-oil is 15.7wt%, and the cycloalkane yield is 2.2wt%.

[0048] Comparative Example 3

[0049] The same as Example 1, except that unsupported iron oxide nanoparticles are used as catalyst, which is denoted as Catalyst C.

[0050] Biomass liquefaction method

[0051] The method comprises the following steps: (1) drying the crop straw after impurities removal at 120°C and 0.01MPa and crushing to a particle size of 1 cm; (2) mixing the crushed and dried biomass, biomass liquefied oil and catalyst in a mass ratio of 100:50:1, and pyrolyzing them at 200°C and 3MPa under hydrogen conditions, wherein the hydrogen partial pressure is 0.5MPa; (3) performing solid-liquid-gas separation on the product at 120°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield of the separated liquid bio-oil is 9.4wt%, and the cycloalkane yield is 0.8wt%.

[0052] Comparative Example 4

[0053] The same as Example 1, except that no ammonium solution was used for activation treatment.

[0054] Catalyst preparation

[0055] The method comprises the following steps: using crop straw as an activated carbon precursor, crushing and sieving to a particle size of 0.1 cm after impurities are removed, and partially carbonizing the crop straw at 500° C. for 30 minutes; immersing the crop straw in a solution with an iron ion concentration of 1 mol / L for 3 hours; and calcining the solution at 200° C. for 5 minutes in an inert nitrogen atmosphere with an oxygen content of 1% by volume to obtain a catalyst D, wherein the carbon content of the carrier is 82% and the iron loading is 4wt%.

[0056] Biomass liquefaction method

[0057] The method comprises the following steps: (1) removing impurities from crop straw, drying it at 120°C and 0.01MPa, and crushing it to a particle size of 1 cm; (2) mixing the crushed and dried biomass, biomass liquefied oil and catalyst in a mass ratio of 100:50:1, and pyrolyzing them at 200°C and 3MPa under hydrogen conditions, wherein the hydrogen partial pressure is 0.5MPa; (3) performing solid-liquid-gas separation on the product at 120°C to obtain liquid bio-oil, combustible gas and solid residue. The hydrocarbon yield in the separated liquid bio-oil is 18.5wt%, and the cycloalkane yield is 6.2wt%.

[0058] It can be seen from the biomass liquefaction methods described in the above examples and comparative examples that the biomass liquefaction method of the present invention can significantly increase the hydrocarbon content, especially the cycloalkane content, in the biomass liquefied oil.

[0059] Those skilled in the art should understand that the above embodiments are only used to illustrate the technical solutions of the present invention and are not used to limit the protection scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A biomass liquefaction method, characterized in that The following steps are involved: (1) removing impurities from the biomass, crushing it and drying it; (2) mixing the biomass after the removal of impurities, crushing it and drying it, a solvent and a catalyst in proportion, and pyrolyzing them at 200-400°C and 0.1-3MPa under anaerobic conditions; (3) performing solid-liquid-gas separation on the product to obtain liquid bio-oil, combustible gas and solid residue; the catalyst in step (2) is partially carbonized activated carbon loaded with iron, and the iron content is 1.5-2wt% based on the total weight of the catalyst; the activated carbon is partially carbonized activated carbon, and the carbon content is 70-73wt% based on the activated carbon carrier; The preparation method of the catalyst comprises the following steps: (a) partially carbonizing an activated carbon precursor; (b) chemically treating the partially carbonized activated carbon precursor obtained in step (a); (c) loading iron; (d) calcining under an inert atmosphere; The partial carbonization in step (a) is carried out at 450-500°C for 10-15 minutes; the chemical treatment in step (b) is to immerse the partially carbonized activated carbon precursor in an ammonium solution with a pH value of 9-11 for 1-12 hours, the molar concentration of ammonium ions in the ammonium solution is 1-3 mol / L, and the immersion time is 1-12 hours; the molar concentration of iron ions in step (c) is 0.5-3 mol / L; the calcination treatment in step (d) is carried out in an inert atmosphere at 200-300°C for 5-30 minutes, the inert atmosphere is carried out in a nitrogen atmosphere, and the inert atmosphere also includes 1-5 volume % of oxygen.

2. The method according to claim 1, characterized in that The solid residue obtained in step (3) is used as a raw material for catalyst preparation.

3. The method according to claim 1, characterized in that The combustible gas obtained in step (3) is used as fuel to provide heat for the pyrolysis reaction.

4. The method according to claim 1, characterized in that The biomass in step (1) is one or more of straw, waste oil, kitchen waste, and sewer sediment; the impurity removal is to remove glass, metal, and sand that cannot be decomposed in the biomass raw material; The pulverizing is to pulverize the biomass and sieve it to obtain particles with a particle size of 0.1-1 cm; the drying is carried out at 90-100° C. and 0.02-0.05 MPa.

5. The method according to claim 1, characterized in that The pyrolysis time in step (2) is 2-3 hours; the pyrolysis temperature is 300-330° C.; the pyrolysis pressure is 1-1.5 MPa; the pyrolysis is carried out under an inert atmosphere, which is one of nitrogen and helium; the mass ratio of biomass, solvent and catalyst in step (2) is 100:80-100:0.5-1.

6. The method according to claim 1, characterized in that The pyrolysis in step (2) is carried out in a reactor selected from the group consisting of a fluidized bed, a slurry bed, and a bubbling bed. Hydrogen is also introduced into the pyrolysis reactor, and the hydrogen partial pressure is 0.1-0.5 MPa.

7. The method according to claim 1, characterized in that The solvent in step (2) is one or more of biomass liquefied oil, coal tar, gasoline, diesel, kerosene, gas oil, and naphtha.

8. The method according to claim 1, characterized in that The solid-liquid-gas separation in step (3) is carried out at 120-150° C., and the separated gas phase is further cooled to separate the water therein; the hydrocarbon content in the bio-oil is above 25wt%.