A continuous biomass catalytic liquefaction method

Abstract

A continuous biomass catalytic liquefaction method comprises the following steps: (1) removing impurities, crushing and drying the biomass, and liquefying it in a biomass liquefaction reactor; (2) mixing the gaseous and liquid components obtained by the reaction and then entering a reforming reactor containing a core-shell catalyst for hydrogenation modification treatment; the core-shell catalyst is a modified ultra-stable Y molecular sieve loaded with a Group VIII metal, and the shell is a small-particle Fe@MIL-101 metal-organic framework material. The method connects multiple parallel biomass liquefaction reactors with a bio-oil reforming reactor to achieve continuous production and reforming of biomass oil; the core-shell catalyst coated with the metal-organic framework material is used to efficiently reform and convert the reaction products, significantly increasing the yield of isoparaffins, reducing the yield of low-carbon hydrocarbons, and improving economic benefits.

Description

Technical Field

[0001] The present invention relates to a biomass liquefaction method, in particular to a method utilizing continuous biomass catalytic liquefaction, and belongs to the field of renewable energy. Background Art

[0002] Biomass liquefaction is a chemical conversion method that converts biomass into high calorific value bio-oil or high value-added small molecule chemicals.

[0003] Biomass feedstock primarily consists of natural polymers such as lignocellulose, which undergo physical and chemical reactions such as depolymerization, cracking, and polymerization under non-thermodynamic equilibrium conditions to form biomass oil. Currently, conventional biomass oil production technologies include thermal cracking and liquefaction, solvent thermal liquefaction, and microwave pyrolysis. The product distribution of biomass pyrolysis depends primarily on the cracking process conditions and the catalyst used. It is generally believed that the yield of pyrolysis oil is highest when the pyrolysis temperature is maintained at a moderate level (500-650°C).

[0004] Biomass oil has a complex composition, including a variety of organic compounds such as alcohols, phenols, aldehydes, carboxylic acids, and hydrocarbons. Biomass oil can be directly used as a fuel source and further processed to replace fossil fuels. It can also be used as a chemical feedstock. However, due to its complex composition, it is difficult to control the product distribution through improved processing conditions. The production of specific chemical feedstocks from biomass oil generally requires subsequent fine processing of the biomass oil.

[0005] During biomass pyrolysis, catalysis can be used to generate targeted components, thereby improving bio-oil quality and reducing the need for reprocessing. The choice of catalyst is crucial in the targeted pyrolysis of biomass. In the absence of a catalyst, the decomposition reaction is thermally activated, producing depolymerization products with the assistance of free radicals. The addition of a catalyst reduces the activation energy of certain reactions, rearranging the reaction pathways and thereby increasing the yield of certain product types.

[0006] Literature has reported that Group VIII metal-loaded molecular sieve catalysts have a significant effect on increasing the hydrocarbon content in bio-oil. However, this type of catalyst also has problems such as easy deactivation due to carbon deposition, and can only perform deoxygenation but cannot perform isomerization.

[0007] Metal-organic frameworks (MOFs), also known as hierarchically porous coordination polymers, are polymers with regular structures composed of secondary building blocks, metal cations or ion clusters, and organic ligands linked through coordination bonds, metallic bonds, or van der Waals forces. They are currently widely used in a variety of technological fields, including gas storage, energy conversion, chemical sensing, drug delivery, and catalysis.

[0008] In catalytic applications, compared to traditional catalysts, MOFs possess not only the stability of inorganic materials but also the diversity of organic materials. Compared to traditional catalysts, MOFs can confine active components within the pores through their own confinement, resulting in catalysts with small, evenly dispersed active component particles, effectively preventing sintering of the active components during calcination. Pyrolysis of MOFs under appropriate conditions can also yield porous metal oxide materials and porous metal oxide / carbon composite catalysts with rich structures and excellent performance. The structure of MOFs can be adjusted by varying the properties of metal cations and linkers, as well as through post-synthesis modification.

[0009] CN105233878A discloses a method for synthesizing a metal-supported MIL-101 bio-oil hydrogenation catalyst. The catalyst is loaded with a transition metal salt and a rare earth metal salt. The hydrodeoxygenation reaction is carried out in a batch reactor under a hydrogen pressure of 2-4 MPa and a temperature of 100-250°C, ultimately yielding a bio-oil hydrodeoxygenation product with good product selectivity.

[0010] CN102057019A discloses a method for producing hydrocarbons from a pyrolysis oil feedstock, comprising: bringing the pyrolysis oil into contact with a partial deoxygenation and hydrogenation catalyst in the presence of hydrogen under deoxygenation conditions, 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 component of a mixed fuel.

[0011] CN102712847A discloses a biomass refining method, comprising dehydrating and drying biomass, directly liquefying the dried biomass to produce crude oil, hydrogenating the crude oil into hydrocarbons; and refining the hydrocarbons into petrochemical products, wherein the hydrogen used in the hydrogenation is obtained from wastewater generated by dehydration and / or direct liquefaction of biomass and residues generated during direct liquefaction.

[0012] The main problems of current metal-organic framework materials in the biomass liquefaction process are easy clogging of the catalyst pore structure and difficulty in catalyst recovery. Summary of the Invention

[0013] Based on the various pore structures and catalytic capabilities of metal-organic framework materials, the present invention utilizes improved catalysts containing metal-organic framework materials to liquefy biomass, which not only reduces the liquefaction reaction temperature, but also significantly increases the yield of organic hydrocarbons in biomass, especially the yield of isoparaffins, and reduces the yield of C1-C4, significantly improving the quality of biomass oil, which is beneficial for the subsequent hydrogenation of the biomass oil full fraction to produce gasoline and diesel. Specifically, the present invention prepares a metal-organic framework catalyst with a specific structure by adjusting the pore structure distribution of the metal-organic framework, adjusting the composition and size of the active metal, and controlling the metal distribution.

[0014] The present invention discloses a continuous biomass catalytic liquefaction method, comprising the following steps: (1) removing impurities, crushing and drying the biomass, and liquefying it in a biomass liquefaction reactor; (2) mixing the gaseous and liquid components obtained by the reaction and then entering a reforming reactor containing a core-shell catalyst for hydrogenation modification treatment; the core-shell catalyst is a modified ultra-stable Y molecular sieve loaded with a Group VIII metal, and the shell is a small-particle Fe@MIL-101 metal organic framework material; the biomass liquefaction reactor in step (1) includes N parallel reactors, wherein N is greater than or equal to 2, and preferably is 3-5; the reforming reactor in step (2) is one of a fluidized bed, a slurry bed and a fixed bed.

[0015] The biomass mainly contains cellulose and / or lignin, including crop straw, wood chips, tree branches, and fallen leaves.

[0016] The biomass liquefaction reactor always maintains one reactor connected to the upgrading reactor, and transports gaseous and liquid materials to the upgrading reactor; the other biomass liquefaction reactors are unloaded or loaded.

[0017] The biomass liquefaction in step (1) is carried out under inert atmosphere conditions. The process conditions for the biomass liquefaction are: temperature of 200-500°C, preferably 330-450°C; pressure of 0.1-3 MPa, more preferably 0.3-0.5 MPa; and particle size of the biomass particles of 0.1-10 cm, more preferably 0.5-3 cm.

[0018] The drying in step (1) is carried out at 80-110°C and 0.05-0.09 MPa, preferably at 90-95°C and 0.07-0.08 MPa.

[0019] The particle size of the core-shell structure catalyst in step (2) is 15-150 nm, preferably 30-50 nm.

[0020] The particle size of the core is 5-50 nm, preferably 10-30 nm; the thickness of the shell is 5-100 nm, preferably 10-20 nm; and the particle size of the small-particle metal organic framework material in the shell is 1-10 nm, preferably 3-6 nm.

[0021] Preferably, the Group VIII metal is one or more of Pt, Pd, Ni, Co, and Fe, more preferably Ni; the loading amount of the Group VIII metal is 0.5-10 wt%, more preferably 3-6 wt%; preferably, the modified Y molecular sieve may further be loaded with an auxiliary agent, and the auxiliary agent is one or more of Group IA elements and / or P and B;

[0022] The hydromodification treatment process conditions in step (2) are: 150-400°C, preferably 200-300°C, pressure 0.5-2MPa, preferably 0.9-1.2MPa, gas-oil volume ratio 100-500:1; volume space velocity 0.1-1h -1 The gas-oil volume ratio is the volume ratio of hydrogen to bio-oil under reaction conditions.

[0023] A method for preparing a core-shell catalyst for biomass liquefaction comprises the following steps:

[0024] (a) Dispersing a Y-type molecular sieve loaded with a Group VIII metal in water, adding a metal organic framework precursor solution, a metal ion solution, and a polymer modifier, and reacting at 140-160°C for 3-6 hours;

[0025] (b) collecting the reaction product, separating the precipitate by filtration, and drying and calcining;

[0026] The precursor solution of the metal organic framework in (a) is Fe 3+ Solution, terephthalic acid, organic solvent; Fe 3+ The solution is one of ferric chloride, ferric nitrate and ferric sulfate; the polymer improver is one of polyethylene, polyurethane and polyacrylamide; the organic solvent is one of N,N-dimethylformamide, pyrrolidone, toluene, benzene and ethanol; the terephthalic acid and Fe 3+ The molar ratio of organic solvent to Fe is 0.5-5, preferably 1-3; 3+ The molar ratio of the organic solvent to the high molecular weight polymer modifier is 3-20, preferably 5-10; the mass ratio of the organic solvent to the high molecular weight polymer modifier is 100:1-5, preferably 100:2-3.

[0027] The drying temperature in step (b) is 90-120°C, preferably 100-110°C; the calcination temperature is 250-400°C, preferably 300-350°C.

[0028] The beneficial technical effects of the present invention are as follows: (1) The present invention realizes the continuous production and modification of biomass oil by connecting multiple parallel biomass liquefaction reactors with bio-oil modification reactors; (2) The biomass liquefaction product is modified by directly connecting the modification reactor to achieve effective utilization of reaction heat; (3) The reaction product is efficiently modified and converted by the core-shell catalyst coated with the metal organic framework material, which significantly improves the yield of isoalkanes, reduces the yield of low-carbon hydrocarbons, and improves economic benefits; (4) The pore size distribution is improved by adding a polymer modifier, which is beneficial to improving the yield of isoalkanes in the product. DETAILED DESCRIPTION Example 1

[0029] The method for preparing a core-shell catalyst comprises the following steps:

[0030] (a) Disperse 10 g of Y molecular sieve loaded with 3 wt% Ni in water, add 16 g of ferric chloride, 43 g of pyrrolidone, and 1.5 g of polyacrylamide, add 16 g of terephthalic acid under stirring, add hydrofluoric acid dropwise until fully precipitated, and react at 140-160°C for 3 h;

[0031] (b) The precipitate was collected by filtration, washed with ethanol, dried at 110°C for 5 min, and calcined at 300°C to obtain a core-shell catalyst;

[0032] A continuous biomass catalytic liquefaction method comprises the following steps:

[0033] (1) The biomass was cleaned and crushed to an average particle size of 1 cm, dried at 90°C and 0.08 MPa for 1 h, and liquefied in a biomass liquefaction reactor under the following liquefaction conditions: temperature 400°C and pressure 1.5 MPa;

[0034] (2) The gas and liquid components obtained by the reaction are mixed and then enter the reforming reactor for modification treatment; the process conditions for the modification treatment are 300℃, pressure 1.2MPa, gas-oil volume ratio 500:1, space velocity 0.5h -1 . Example 2

[0035] The method for preparing a core-shell catalyst comprises the following steps:

[0036] (a) 8 g of Y molecular sieve loaded with 5 wt% Ni was dispersed in water, 16 g of ferric chloride, 65 g of pyrrolidone, and 1.5 g of polyacrylamide were added, and 16 g of terephthalic acid was added under stirring. Hydrofluoric acid was added dropwise until sufficient precipitation was achieved, and the reaction was carried out at 140°C for 5 h.

[0037] (b) The precipitate was collected by filtration, washed with ethanol, dried at 110°C for 8 min, and calcined at 350°C to obtain a core-shell catalyst;

[0038] A continuous biomass catalytic liquefaction method comprises the following steps:

[0039] (1) The biomass was cleaned and crushed to an average particle size of 4 cm, dried at 90°C and 0.08 MPa for 1 h, and liquefied in a biomass liquefaction reactor under the following liquefaction conditions: temperature 450°C and pressure 1.0 MPa;

[0040] (2) The gas and liquid components obtained by the reaction are mixed and then enter the reforming reactor for modification treatment; the process conditions for the modification treatment are 300℃, pressure 1.2MPa, gas-oil volume ratio 400:1, space velocity 0.5h -1 . Example 3

[0041] The method for preparing a core-shell catalyst comprises the following steps:

[0042] (a) 8 g of Y molecular sieve loaded with 0.5 wt% Pt was dispersed in water, 16 g of ferric chloride, 73 g of N,N-dimethylformamide, and 1.5 g of polypropylene were added, and 16 g of terephthalic acid was added under stirring. Hydrofluoric acid was added dropwise until sufficient precipitation was achieved, and the reaction was carried out at 160°C for 3 h.

[0043] (b) collecting the precipitate by filtration, washing with ethanol, drying at 100°C for 10 min, and calcining at 400°C to obtain a core-shell catalyst;

[0044] A continuous biomass catalytic liquefaction method comprises the following steps:

[0045] (1) The biomass was cleaned and crushed to an average particle size of 2 cm, dried at 95°C and 0.08 MPa for 1 h, and liquefied in a biomass liquefaction reactor under the following liquefaction conditions: temperature of 380°C and pressure of 1.2 MPa;

[0046] (2) The gas and liquid components obtained by the reaction are mixed and then enter the reforming reactor for modification treatment; the process conditions for the modification treatment are 300℃, pressure 1.2MPa, gas-oil volume ratio 500:1, space velocity 0.5h -1 .

[0047] Comparative Example 1

[0048] Other aspects are the same as those in Example 1, except that the bio-oil reforming catalyst is iron-loaded MIL-101.

[0049] Comparative Example 2

[0050] Other aspects are the same as those in Example 1, except that the bio-oil reforming catalyst is a nickel-loaded Y molecular sieve.

[0051] Comparative Example 3

[0052] Other aspects are the same as those in Example 1, except that no high molecular weight polymer improver is added to the bio-oil reforming catalyst.

[0053] The bio-oils obtained in Examples 1-3 and Comparative Examples 1-3 were analyzed, and their compositions are shown in Table 1:

[0054]

[0055] The biomass conversion rate refers to the mass ratio of the obtained biomass oil to the biomass raw material before liquefaction; the alkane yield is the mass ratio of the obtained alkanes to the biomass raw material before liquefaction; and the isoparaffin yield is the mass ratio of isoparaffins to the biomass raw material before liquefaction.

[0056] Through the performance analysis of the above comparative examples, it can be clearly seen that the method of the present invention has the characteristics of high alkane yield, high biomass conversion rate, high isoparaffin yield, and low C1-C4 yield, and has achieved significant progress and unexpected technical effects.

[0057] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A continuous biomass catalytic liquefaction method comprising the following steps: (1) The biomass is removed from impurities, crushed and dried, and then liquefied in a biomass liquefaction reactor; (2) the gaseous and liquid components obtained by the reaction are mixed and then enter a reforming reactor containing a core-shell catalyst for hydrogenation modification treatment; the core of the core-shell catalyst is a modified ultra-stable Y molecular sieve loaded with a Group VIII metal, and the shell is a small-particle Fe@MIL-101 metal-organic framework material; the biomass liquefaction reactor in step (1) includes N parallel reactors, and N is greater than or equal to 2; the reforming reactor in step (2) is one of a fluidized bed, a slurry bed and a fixed bed; The core-shell catalyst preparation method comprises the following steps: (a) Dispersing a modified ultrastable Y molecular sieve loaded with a Group VIII metal in water, adding a metal organic framework precursor solution, a metal ion solution, and a polymer modifier, and reacting at 140-160° C. for 3-6 hours; (b) The reaction product is collected, the precipitate is separated by filtration, and then dried and calcined.

2. The method according to claim 1, wherein: The N is 3-5.

3. The method according to claim 1, wherein: The biomass mainly contains cellulose and / or lignin, including crop straw, wood chips, tree branches or fallen leaves.

4. The method according to claim 1, wherein The biomass liquefaction reactor always maintains one reactor connected to the upgrading reactor, and transports gaseous and liquid materials to the upgrading reactor; the other biomass liquefaction reactors are unloaded or loaded.

5. The method according to claim 1, wherein The biomass liquefaction in step (1) is carried out under inert atmosphere conditions. The process conditions for the biomass liquefaction are: temperature of 200-500°C; pressure of 0.1-3 MPa; and particle size of the biomass particles of 0.1-10 cm.

6. The method according to claim 5, wherein: The temperature is 330-450° C., the pressure is 0.3-0.5 MPa, and the particle size of the biomass particles is 0.5-3 cm.

7. The method according to claim 1, wherein The drying in step (1) is carried out at 80-110° C. and 0.05-0.09 MPa.

8. The method according to claim 7, wherein: The drying in step (1) is carried out at 90-95°C and 0.07-0.08 MPa.

9. The method according to claim 1, wherein The particle size of the core-shell catalyst in step (2) is 15-150 nm; The particle size of the core is 5-50 nm; the thickness of the shell is 5-100 nm; and the particle size of the small-particle metal organic framework material in the shell is 1-10 nm.

10. The method according to claim 9, wherein The particle size of the core-shell catalyst in step (2) is 30-50 nm; The particle size of the core is 10-30 nm; the thickness of the shell is 10-20 nm; and the particle size of the small-particle metal-organic framework material of the shell is 3-6 nm.

11. The method according to claim 1, wherein The Group VIII metal is one or more of Pt, Pd, Ni, Co, and Fe; the loading amount of the Group VIII metal is 0.5-10 wt%; the modified ultrastable Y molecular sieve is further loaded with an auxiliary agent, and the auxiliary agent is one or more of Group IA elements and / or P and B; The modification treatment process conditions in step (2) are 150-400°C, pressure 0.5-2MPa, gas-oil volume ratio 100-500:1; volume space velocity 0.1-1h -1 .

12. The method according to claim 11, wherein The Group VIII metal is Ni; the loading amount of the Group VIII metal is 3-6 wt %; The modification treatment process conditions in step (2) are 200-300°C and 0.9-1.2 MPa.

13. The method according to claim 1, wherein The precursor solution of the metal organic framework in (a) is Fe 3+ solution, terephthalic acid and organic solvent; Fe 3+ The solution is one of ferric chloride, ferric nitrate and ferric sulfate; the polymer improver is one of polyethylene, polyurethane and polyacrylamide; the organic solvent is one of N,N-dimethylamide, pyrrolidone, toluene, benzene and ethanol; the terephthalic acid and Fe 3+ The molar ratio of organic solvent to Fe is 0.5-5; 3+ The molar ratio of the organic solvent to the high molecular polymer modifier is 3-20; the mass ratio of the organic solvent to the high molecular polymer modifier is 100:1-5.

14. The method according to claim 13, wherein: The terephthalic acid and Fe 3+ The molar ratio of organic solvent to Fe is 1-3; 3+ The molar ratio of organic solvent to polymer modifier is 5-10; the mass ratio of organic solvent to polymer modifier is 100:2-3.

15. The method according to claim 1, wherein The drying temperature in step (b) is 90-120°C; the calcination temperature is 250-400°C.

16. The method according to claim 15, wherein The drying temperature in step (b) is 100-110°C; the calcination temperature is 300-350°C.

Images