Process for producing biomass fuel oil by utilizing biological fibers

Abstract

The invention belongs to the technical field of sustainable biological fuel oil production, and particularly relates to a process for producing biomass fuel oil by using biological fibers. The method comprises the following steps: S1, pretreating a bio-fiber raw material; s2, carrying out synergistic catalytic conversion and deoxidation on biochemical conversion to obtain crude biological fuel oil; and S3, carrying out nano modification and product refining to obtain the biomass fuel oil. According to the method, a segmented hydrolysis-separation technology is adopted, a physical open chain-chemical bond breaking synergistic mode is formed through high-temperature liquid water self-ionization and maleic acid hydrolysis of cellulose to generate glucose, S / Cl pollution is reduced, Ni / Al2O3-SiO2 hydrogenation and HZSM-5 molecular sieve shape-selective catalysis are coupled, and an oxygen-containing body is converted into saturated alkane; a sodium lignin sulfonate amphiphilic structure constructs a carbon tube-hydrocarbon chain stable dispersion system, a nano core-hydrocarbon shell structure is formed by combining a high-pressure homogeneous cavitation effect, and biofuel oxygen-containing polar molecules and a nano material synergistically improve the combustion rate and the energy release uniformity.

Description

Technical Field

[0001] The present invention belongs to the technical field of sustainable biofuel production, and particularly relates to a process for producing biomass fuel using biofibers. Background Art

[0002] With the dual pressures of growing global energy demand and the shortage of fossil fuel resources, biomass energy has received extensive attention as a renewable low-carbon alternative. Currently, biomass fuel production technologies mainly focus on three directions: oil ester exchange, starch saccharification fermentation, and lignocellulose conversion. Among them, biodiesel technology using waste oil and ethanol gasoline technology using corn and sugarcane as raw materials have been industrialized, but these technologies generally face problems such as limited raw material sources. At present, the mainstream preparation technologies of biomass fuel include pyrolysis liquefaction, gasification synthesis, enzymatic hydrolysis fermentation, and transesterification. For example, rapid pyrolysis technology decomposes biomass under high-temperature and anaerobic conditions to produce bio-oil, but the bio-oil produced by traditional processes generally has problems such as high oxygen content, strong acidity, low calorific value, and poor stability, which easily lead to polymerization reactions during storage, forming gum precipitation, seriously limiting its direct application as fuel. In recent years, lignocellulosic biomass has gradually become the focus of research on second-generation biofuels because it widely exists in agricultural wastes (such as straws, rice husks), forestry processing residues (such as wood chips, barks), and energy crops (such as switchgrass, miscanthus). However, the complex supramolecular structure of lignocellulose makes it difficult to be directly converted. Existing pretreatment technologies such as dilute acid hydrolysis, steam explosion, and organic solvent separation can break the lignin-hemicellulose cross-linking network, but generally have problems such as high energy consumption, large consumption of chemical reagents, and pollution of pretreatment waste liquid. In the conversion link, the enzymatic hydrolysis fermentation route is limited by the high cost of cellulase and inhibitor tolerance, while in the thermochemical conversion route, although rapid pyrolysis can directly produce bio-crude oil, the products have defects such as high oxygen content, low calorific value, and strong corrosiveness, and need to be upgraded by catalytic hydrodeoxygenation to meet the vehicle fuel standard, resulting in high overall process costs. Therefore, based on the above problems, it is extremely necessary to develop an environmentally friendly and efficient biomass fuel production process. Summary of the Invention

[0003] Aiming at the defects of the prior art, the purpose of the present invention is to provide a process for producing biomass fuel using biofibers.

[0004] The technical effects described in the present invention are achieved through the following technical solutions: A process for producing biomass fuel using biofibers, which comprises the following steps: S1: Pretreatment of biofiber raw materials; S2: Biochemical conversion combined with catalytic conversion and deoxygenation to obtain crude biofuel; S3: Nano-modification and fuel refining to obtain biomass fuel; Preferably, in step S1, the specific steps of the pretreatment of the biofiber raw material are as follows: S101: Dry the straw at 80 - 100 °C until the water content < 10%, then crush it to a particle size of 0.5 - 2 mm to obtain a biomass raw material; Treat the biomass raw material at 180 - 200 °C and a pressure of 1.5 - 2 MPa for 10 - 20 min, then add 2 - 3% maleic acid and deionized water, and treat it at a temperature of 150 - 160 °C for 30 - 60 min to obtain a hydrolysis solution; S102: Centrifuge the hydrolysis solution prepared in step S101 at a rotation speed of 5000 rpm for 10 - 15 min, filter it, add 1 - 2% activated carbon, perform adsorption treatment for 1 - 2 h, filter it through a 0.2 - μm ceramic membrane, and concentrate it under vacuum at 60 °C until the sugar concentration is 100 - 120 g / L to obtain a pretreated biofiber; Preferably, in step S2, the specific steps of the biochemical conversion synergistic catalytic conversion and deoxygenation are as follows: S201: Mix the pretreated biofiber prepared in step S102 with continuously introduced hydrogen, preheat it to 120 °C at a heating rate of 2 - 3 °C / min, and add a nickel-based catalyst Ni / Al2O3 - SiO2 accounting for 6% of the mass of the pretreated biofiber for primary catalytic deoxygenation; S202: After completing the catalytic deoxygenation operation in step S201, perform staged treatment of low-temperature alkylation and high-temperature deoxygenation refining; After the treatment is completed, the reaction product is subjected to multi-stage condensation separation of unreacted hydrogen and liquid crude fuel at 20 °C, 10 °C, and - 10 °C, and the liquid crude fuel is subjected to atmospheric distillation, and the fraction with a boiling range of 30 - 100 °C is collected in segments to obtain crude biofuel; Preferably, in step S201, the nickel-based catalyst Ni / Al2O3 - SiO2 is a catalyst that can be directly purchased through conventional channels; Preferably, in step S201, the parameters of the primary catalytic deoxygenation treatment include: a fixed-bed continuous reactor at 160 - 210 °C, a pressure of 4 MPa, and a residence time of 30 - 60 min; Preferably, in step S202, the parameters of the low-temperature alkylation treatment include: a nickel-based catalyst Ni / HZSM - 5 accounting for 6% of the substrate mass, a temperature of 210 - 230 °C, a pressure of 3.5 - 4 MPa, and a residence time of 60 - 90 min; Preferably, in step S202, the parameters of the high-temperature deoxygenation refining treatment include: a phosphorus-modified nickel-based catalyst Ni - P / HZSM - 5 accounting for 8% of the substrate mass, a temperature of 250 - 270 °C, a pressure of 3.5 MPa, a hydrogen circulation rate of 200 - 300 L / h, and a time of 30 - 45 min; Preferably, in step S202, the nickel-based catalyst Ni / HZSM-5 is a catalyst that can be directly purchased through conventional channels; Preferably, in step S202, the specific preparation steps of the phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 are as follows: S301: Calcinate the HZSM-5 molecular sieve at 550 °C for 4 - 5 h, then mix it with a 1 M ammonium nitrate solution, stir at 80 °C for 2 - 3 h, filter, repeat the stirring treatment 3 times, centrifuge and filter, wash until neutral, and dry at 110 °C for 8 - 12 h to obtain pretreated HZSM-5; S302: Immerse the pretreated HZSM-5 prepared in step S301 in a 0.1 - 0.3 M nickel nitrate solution, stir at 80 °C for 4 - 5 h, centrifuge and filter, dry at 110 °C for 8 - 12 h, then heat up to 500 °C at a rate of 5 °C / min in a tube furnace, calcine in an air atmosphere for 4 h, then switch to H2 with a flow rate of 50 mL / min and reduce at 450 °C for 3 h to obtain Ni / HZSM-5; S303: Mix the Ni / HZSM-5 prepared in step S302 with a 30 wt% phosphoric acid solution, let it stand at room temperature for 12 h, dry at 110 °C for 8 - 12 h, then heat up to 550 °C at a rate of 2 °C / min in a muffle furnace, calcine in an air atmosphere for 4 h, and then perform hydrothermal aging treatment at 600 °C in a 100% steam atmosphere for 8 - 12 h to obtain Ni-P / HZSM-5; Preferably, in step S301, the dosage ratio of the HZSM-5 molecular sieve to the ammonium nitrate solution is 1 g:10 - 12 mL; Preferably, in step S302, the dosage ratio of the pretreated HZSM-5 to the nickel nitrate solution is 1 g:5 mL; Preferably, in step S303, the dosage ratio of the Ni / HZSM-5 to the 30 wt% phosphoric acid solution is 1 g:0.3 - 0.5 mL; Preferably, in step S3, the specific steps of the nano-modification and fuel refining are as follows: S401: Mix carbon nanotubes and sodium lignosulfonate in proportion, add them to deionized water, and perform ultrasonic treatment with parameters of 200 - 300 W, 40 kHz, and a time of 20 - 30 min to obtain a nano-slurry; S402: Mix the crude biofuel prepared in step S402 and the nano-slurry prepared in step S401 in proportion, treat at a rotation speed of 8000 - 10000 rpm for 20 - 30 min, and then perform homogenization treatment 3 times at 40 - 50 MPa; S403: After the homogenization treatment in step S402 is completed, hydrocarbon components with a boiling range of 30 to 80° C. are collected in stages at a pressure of 10 to 15 kPa to obtain biomass fuel; Preferably, in step S401, the ratio of the carbon nanotubes, sodium lignin sulfonate and deionized water is 2-3 g: 5-6 g: 100 mL; Preferably, in step S402, the volume ratio of the crude biofuel to the nano-slurry is 100-120:1.

[0005] The beneficial effects of the present invention are as follows: The process of the present invention is carried out through segmented hydrolysis and selective separation of components. First, high-temperature liquid water pretreatment is performed. Through the self-ionization characteristics of water, the β-1,4 glycosidic bonds of hemicellulose are selectively broken under extremely low chemical additive conditions to release pentose such as xylose, while retaining the integrity of the cellulose skeleton to create a loose structure for subsequent acid catalysis; the mild acidity of bio-based maleic acid is used to attack the amorphous region of cellulose and generate glucose in a direction, thereby avoiding excessive degradation of sugars or lignin condensation caused by strong acid and controlling the impurity spectrum of the product from the source; the two-stage treatment forms a synergistic mode of physical chain opening and chemical bond breaking, effectively avoiding the introduction of non-C / H / O elements such as sulfur (S) and chlorine (Cl), ensuring the purity of the product components, and realizing the cascade utilization of hemicellulose and cellulose, providing a high-activity, low-inhibitor sugar liquid raw material for downstream catalytic conversion. Through the hydrogenation activity of Ni / Al2O3-SiO2 and the shape-selective effect of HZSM-5 molecular sieve, oxygen-containing intermediates are directed to be converted into saturated alkanes. Through the synergy of high-temperature liquid water pretreatment and weak acid hydrolysis, hemicellulose and cellulose are directed to be deconstructed to provide highly active sugar solution for catalytic deoxygenation. The two-stage nickel-based catalyst takes into account both catalyst life and deoxygenation efficiency through the synergy of low-temperature protection and high-temperature deep deoxidation. In the subsequent process, sodium lignin sulfonate, with its amphiphilic structure, embeds one end into the surface defect of carbon nanotubes, and forms a hydrophobic effect with the fuel hydrocarbon chain at the other end, constructing a stable dispersion system and solving the problem of nanoparticle agglomeration. After the light impurities are removed by vacuum distillation, the cavitation effect generated by high-pressure homogenization further destroys the nano aggregates, so that the modifier is evenly embedded in the gap between fuel molecules to form a nano core-hydrocarbon shell composite structure. In addition, the high thermal conductivity of nanomaterials accelerates fuel gasification, while the oxygen-containing polar molecules of biofuels enhance the wettability of the nano interface. The two synergistically improve the combustion rate and energy release uniformity. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings in the following description are only for the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0007] Figure 1 It is the biodiesel yield graph prepared by the processes of Embodiments 1-3 and Comparative Examples 1-4 of the present invention. Detailed implementation manners

[0008] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments; based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention. It should be noted that unless otherwise specified, the raw materials involved in the present invention are purchased through conventional commercial channels.

[0009] Embodiment 1: A process for producing biomass fuel using biofibers, which comprises the following steps: S1: Pretreatment of biofiber raw materials; S101: Dry 1000 g of straw at 90 °C until the water content < 10%, and then crush it to a particle size of 1 mm to obtain a biomass raw material; treat the biomass raw material at 190 °C and a pressure of 1.8 MPa for 15 min, and then add 25 g of maleic acid and 500 mL of deionized water, and treat it at a temperature of 155 °C for 50 min to obtain a hydrolysis solution; S102: Centrifuge the hydrolysis solution prepared in step S101 at a speed of 5000 rpm for 12 min, filter it, add 1.5% activated carbon, perform adsorption treatment for 1.5 h, filter it through a 0.2 μm ceramic membrane, and concentrate it in vacuum at 60 °C to a sugar concentration of 100 g / L to obtain pretreated biofibers; S2: Biochemical conversion combined with catalytic conversion and deoxygenation to obtain crude biodiesel; S201: Mix 200 mL of the pretreated biofibers prepared in step S102 with continuously introduced hydrogen, preheat it to 120 °C at a heating rate of 2.5 °C / min, add a nickel-based catalyst Ni / Al2O3-SiO2 accounting for 6% of the substrate mass for primary catalytic deoxygenation, in a fixed-bed continuous reactor at 185 °C, a pressure of 4 MPa, and a residence time of 45 min; S202: After completing the catalytic deoxidation operation in step S201, carry out alkylation treatment in the low-temperature section with a 6% nickel-based catalyst Ni / HZSM-5 by substrate mass, at a temperature of 220 °C, a pressure of 3.8 MPa, and a residence time of 75 min; the high-temperature section deoxidation and refining are carried out in stages with an 8% phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 by substrate mass, at a temperature of 260 °C, a pressure of 3.5 MPa, a hydrogen circulation rate of 250 L / h, and a time of 38 min; after the treatment is completed, the reaction products are subjected to multi-stage condensation separation of unreacted hydrogen and liquid crude fuel at 20 °C, 10 °C, and -10 °C, and the liquid crude fuel is subjected to atmospheric distillation, and the components with a boiling range of 30-100 °C are collected in segments to obtain crude biofuel; The specific preparation steps of the phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 are as follows: S301: Calcinate 10 g of HZSM-5 molecular sieve at 550 °C for 4.5 h, then mix it with 100 mL of 1 M ammonium nitrate solution, stir at 80 °C for 2.5 h, filter, repeat the stirring treatment 3 times, centrifuge and filter, wash until neutral, and dry at 110 °C for 8 h to obtain pretreated HZSM-5; S302: Immerse 10 g of the pretreated HZSM-5 prepared in step S301 in 50 mL of 0.2 M nickel nitrate solution, stir at 80 °C for 4 h, centrifuge and filter, dry at 110 °C for 8 h, then heat up to 500 °C at a rate of 5 °C / min in a tubular furnace, calcine in an air atmosphere for 4 h, and then switch to H2 with a flow rate of 50 mL / min and reduce at 450 °C for 3 h to obtain Ni / HZSM-5; S303: Mix 10 g of Ni / HZSM-5 prepared in step S302 with 4 mL of 30 wt% phosphoric acid solution, let it stand at room temperature for 12 h, dry at 110 °C for 8 h, then heat up to 550 °C at a rate of 2 °C / min in a muffle furnace, calcine in an air atmosphere for 4 h, and then carry out hydrothermal aging treatment at 600 °C in a 100% steam atmosphere for 10 h to obtain Ni-P / HZSM-5; S3: Nano-modification and fuel refining to obtain biofuel; S401: Mix 0.3 g of carbon nanotubes and 0.6 g of sodium lignosulfonate in proportion, add 10 mL of deionized water, and perform ultrasonic treatment with parameters of 300 W, 40 kHz, and a time of 20 min to obtain a nano-slurry; S402: Mix 200 mL of the crude biofuel prepared in step S402 and 2 mL of the nano-slurry prepared in step S401 in proportion, treat at a rotation speed of 8000 rpm for 30 min, and then homogenize at 50 MPa for 3 times; S403: After the homogenization treatment in step S402 is completed, hydrocarbon components with a boiling range of 30-80 °C are collected in segments at a pressure of 15 kPa to obtain biofuel.

[0010] Example 2: A process for producing biofuel using biofibers, which comprises the following steps: S1: Pretreatment of biofiber raw materials; S101: 1000 g of straw is dried at 80 °C until the water content < 10%, and then crushed to a particle size of 0.5 mm to obtain a biomass raw material; the biomass raw material is treated at 180 °C and a pressure of 1.5 MPa for 10 min, then 20 g of maleic acid and 200 mL of deionized water are added, and the treatment is carried out at a temperature of 150 °C for 30 min to obtain a hydrolysis solution; S102: The hydrolysis solution prepared in step S101 is centrifuged at a speed of 5000 rpm for 10 min, filtered, 1% activated carbon is added, adsorbed for 1 h, filtered through a 0.2 μm ceramic membrane, and vacuum concentrated at 60 °C to a sugar concentration of 120 g / L to obtain pretreated biofibers; S2: Biochemical conversion combined with catalytic conversion and deoxygenation to obtain crude biofuel; S201: 200 mL of the pretreated biofibers prepared in step S102 is mixed with continuously introduced hydrogen, preheated to 120 °C at a heating rate of 2 °C / min, and 6% of the substrate mass of the nickel-based catalyst Ni / Al2O3-SiO2 is added for primary catalytic deoxygenation. The fixed-bed continuous reactor is at 160 °C, a pressure of 4 MPa, and a residence time of 30 min; S202: After the catalytic deoxygenation operation in step S201 is completed, low-temperature alkylation treatment is carried out. The nickel-based catalyst Ni / HZSM-5 is 6% of the substrate mass, the temperature is 210 °C, the pressure is 3.5 MPa, and the residence time is 60 min; the high-temperature deoxygenation and refining are carried out in stages. The phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 is 8% of the substrate mass, the temperature is 250 °C, the pressure is 3.5 MPa, the hydrogen circulation rate is 200 L / h, and the time is 30 min; after the treatment is completed, the reaction products are subjected to multi-stage condensation separation at 20 °C, 10 °C, and -10 °C to separate unreacted hydrogen and liquid crude fuel. The liquid crude fuel is subjected to atmospheric distillation, and the components with a boiling range of 30-100 °C are collected in segments to obtain crude biofuel; The specific preparation steps of the phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 are as follows: S301: 10 g of HZSM-5 molecular sieve is calcined at 550 °C for 4 h, then mixed with 110 mL of 1M ammonium nitrate solution, stirred at 80 °C for 2 h, filtered, the stirring treatment is repeated 3 times, centrifuged and filtered, washed to neutral, and dried at 110 °C for 10 h to obtain pretreated HZSM-5; S302: Immerse 10 g of the pretreated HZSM-5 prepared in step S301 in 50 mL of 0.1 M nickel nitrate solution, stir at 80 °C for 4.5 h, centrifuge and filter, dry at 110 °C for 10 h, then heat up to 500 °C at a rate of 5 °C / min in a tube furnace, calcine in air atmosphere for 4 h, then switch to H2 with a flow rate of 50 mL / min and reduce at 450 °C for 3 h to obtain Ni / HZSM-5; S303: Mix 10 g of Ni / HZSM-5 prepared in step S302 with 3 mL of 30 wt% phosphoric acid solution, let stand at room temperature for 12 h, dry at 110 °C for 10 h, then heat up to 550 °C at a rate of 2 °C / min in a muffle furnace, calcine in air atmosphere for 4 h, and then perform hydrothermal aging treatment at 600 °C in 100% steam atmosphere for 12 h to obtain Ni-P / HZSM-5; S3: Nano-modification and fuel refining to obtain biofuel; S401: Mix 0.2 g of carbon nanotubes and 0.5 g of sodium lignosulfonate in proportion, add 10 mL of deionized water, and perform ultrasonic treatment with parameters of 200 W, 40 kHz, and time of 25 min to obtain a nano-slurry; S402: Mix 120 mL of the crude biofuel prepared in step S402 and 1 mL of the nano-slurry prepared in step S401 in proportion, treat at a rotation speed of 8000 rpm for 25 min, and then perform homogenization treatment 3 times at 40 MPa; S403: After completing the homogenization treatment in step S402, collect the hydrocarbon components with a boiling range of 30 - 80 °C in segments under a pressure of 10 kPa to obtain biofuel.

[0011] Example 3: A process for producing biofuel using biofibers, which includes the following steps: S1: Pretreatment of biofiber raw materials; S101: Dry 1000 g of straw at 100 °C until the water content < 10%, then crush it to a particle size of 2 mm to obtain a biomass raw material; treat the biomass raw material at 180 - 200 °C and a pressure of 2 MPa for 20 min, then add 30 g of maleic acid and 200 mL of deionized water, and treat at a temperature of 160 °C for 60 min to obtain a hydrolysis solution; S102: Centrifuge the hydrolysis solution prepared in step S101 at a rotation speed of 5000 rpm for 15 min, filter, add 2% activated carbon, perform adsorption treatment for 2 h, filter with a 0.2 μm ceramic membrane, and concentrate in vacuum at 60 °C until the sugar concentration reaches 110 g / L to obtain pretreated biofibers; S2: Biochemical conversion, synergistic catalytic conversion and deoxygenation to obtain crude biofuel; S201: Mix the 200 mL of pretreated biofibers prepared in step S102 with continuously introduced hydrogen, preheat it to 120 °C at a heating rate of 3 °C / min, add a nickel-based catalyst Ni / Al2O3-SiO2 accounting for 6% of the substrate mass for primary catalytic deoxygenation. The fixed-bed continuous reactor is at 210 °C, the pressure is 4 MPa, and the residence time is 60 min; S202: After completing the catalytic deoxygenation operation in step S201, perform alkylation treatment in the low-temperature section with a nickel-based catalyst Ni / HZSM-5 accounting for 6% of the substrate mass, at a temperature of 230 °C, a pressure of 4 MPa, and a residence time of 90 min; The high-temperature section of deoxygenation and refining is processed in stages with a phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 accounting for 8% of the substrate mass, at a temperature of 270 °C, a pressure of 3.5 MPa, a hydrogen circulation rate of 300 L / h, and a time of 45 min; After the treatment is completed, the reaction products are subjected to multi-stage condensation separation at 20 °C, 10 °C, and -10 °C to separate unreacted hydrogen and liquid crude fuel oil. The liquid crude fuel oil is subjected to atmospheric distillation, and the fractions with a boiling range of 30 - 100 °C are collected in segments to obtain crude biofuel; The specific preparation steps of the phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 are as follows: S301: Calcinate 10 g of HZSM-5 molecular sieve at 550 °C for 5 h, then mix it with 120 mL of 1M ammonium nitrate solution, stir at 80 °C for 3 h, filter, repeat the stirring treatment 3 times, centrifuge and filter, wash until neutral, and dry at 110 °C for 12 h to obtain pretreated HZSM-5; S302: Immerse 10 g of the pretreated HZSM-5 prepared in step S301 in 50 mL of 0.3M nickel nitrate solution, stir at 80 °C for 5 h, centrifuge and filter, dry at 110 °C for 12 h, then heat it to 500 °C at a rate of 5 °C / min in a tube furnace, calcine in an air atmosphere for 4 h, and then switch to H2 with a flow rate of 50 mL / min and reduce at 450 °C for 3 h to obtain Ni / HZSM-5; S303: Mix 10 g of Ni / HZSM-5 prepared in step S302 with 5 mL of 30 wt% phosphoric acid solution, let it stand at room temperature for 12 h, dry at 110 °C for 12 h, then heat it to 550 °C at a rate of 2 °C / min in a muffle furnace, calcine in an air atmosphere for 4 h, and then perform hydrothermal aging treatment at 600 °C in a 100% steam atmosphere for 8 h to obtain Ni-P / HZSM-5; S3: Nano-modification and fuel refining to obtain biofuel; S401: Mix 0.25 g of carbon nanotubes and 0.6 g of sodium lignosulfonate in proportion, add 10 mL of deionized water, and perform ultrasonic treatment with parameters of 250 W, 40 kHz, and a time of 30 min to obtain a nano-slurry; S402: Mix 110 mL of the crude biofuel prepared in step S402 and 1 mL of the nano-slurry prepared in step S401 in proportion, process at a rotation speed of 9000 rpm for 20 min, and then perform homogenization treatment three times at 45 MPa; S403: After completing the homogenization treatment in step S402, collect the hydrocarbon components with a boiling range of 30 - 80 °C in segments under a pressure of 12 kPa to obtain biofuel.

[0012] Comparative Example 1: The operation of Comparative Example 1 is basically the same as that of Example 1, except that maleic acid is not used for pretreatment in Comparative Example 1.

[0013] Comparative Example 2: The operation of Comparative Example 2 is basically the same as that of Example 1, except that the unmodified Ni / HZSM-5 catalyst is used to replace the phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 in Comparative Example 2.

[0014] Comparative Example 3: The operation of Comparative Example 3 is basically the same as that of Example 1, except that the multi-stage condensation at 20 °C, 10 °C, and -10 °C in step S202 of Comparative Example 3 is changed to single-stage condensation at 0 °C.

[0015] Comparative Example 4: The operation of Comparative Example 4 is basically the same as that of Example 1, except that carbon nanotubes are not added in step S401 of Comparative Example 4, and only sodium lignosulfonate is used.

[0016] Yield test: Calculate the biofuel yields prepared by the processes of the above Examples 1 - 3 and Comparative Examples 1 - 4. The biofuel yield (%) = (mass of the final biofuel / mass of the raw material before pretreatment) × 100%. The results are as Figure 1 shown.

[0017] As Figure 1 can be seen from the results, the process of the present invention has an excellent biofuel yield. In particular, the parameter performance of Example 1 shows the best process effect; from the results of Comparative Example 1, it can be seen that the lack of maleic acid leads to insufficient deconstruction of the amorphous region of cellulose, an increase in the degradation rate of sugars, an increase in lignin condensation by-products, an increase in mass loss during the pretreatment stage, and a synchronous decrease in the subsequent catalytic conversion rate, thereby resulting in a significant decrease in the yield; from the results of Comparative Example 2, it can be seen that the deoxygenation efficiency of the unmodified catalyst decreases significantly, and the increase in by-products leads to a loss in fuel quality and a significant decrease in the yield; from the results of Comparative Example 3, it can be seen that due to the lack of the multi-stage condensation process, the recovery rate of C5 - C12 light components decreases significantly, the residual high-boiling components lead to an increase in the cold filter point of the fuel, and the mass loss of the light fuel after distillation is significant, resulting in a significant decrease in the yield.

[0018] Performance test: The yields of the biofuels prepared by the processes of Example 1 and Comparative Examples 1-4 were tested. The kinematic viscosity was tested in accordance with GB / T 265-1988, the flash point of the biomass fuel was tested in accordance with GB / T 21789-2008, the color was observed and recorded, and the acid value of the biomass fuel was tested in accordance with GB / T 7304-2020. The results are shown in Table 1 below.

[0019] Table 1. Performance test results of biomass fuel

[0020] As can be seen from the results in Table 1, the biomass fuel prepared by the process of the present invention has excellent chemical properties and is transparent in color without impurities.

[0021] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for producing biomass fuel using biofiber, characterized in that: It includes the following steps: S1: pretreatment of biofiber raw materials; S2: Biochemical conversion with catalytic conversion and deoxygenation to obtain crude biofuel; S3: Nano-modification and fuel refining to obtain biomass fuel.

2. The process for producing biomass fuel using biofiber according to claim 1, characterized in that: In step S1, the specific steps of pre-treating the biofiber raw material are as follows: S101: drying the straw and then crushing it to obtain a biomass raw material; treating the biomass raw material at high temperature and high pressure, then adding maleic acid and deionized water, and treating it at high temperature to obtain a hydrolyzate; S102: The hydrolyzate prepared in step S101 is centrifuged, filtered, activated carbon is added, adsorbed, filtered, and vacuum concentrated to obtain pretreated biofiber.

3. The process for producing biomass fuel using biofiber according to claim 2, characterized in that: In step S2, the specific steps of the biochemical conversion coordinated with catalytic conversion and deoxygenation are as follows: S201: mixing the pretreated biofiber prepared in step S102 with hydrogen gas continuously introduced, preheating, and then adding a nickel-based catalyst Ni / Al2O3-SiO2 for primary catalytic deoxidation; S202: After the catalytic deoxygenation operation in step S201 is completed, the low-temperature section alkylation treatment and the high-temperature section deoxygenation refining treatment are carried out in stages; after the treatment is completed, the reaction product is subjected to multi-stage condensation to separate unreacted hydrogen and liquid crude fuel oil, the liquid crude fuel oil is subjected to atmospheric distillation, and the components with a boiling range of 30 to 100°C are collected in stages to obtain crude biofuel.

4. The process for producing biomass fuel using biofiber according to claim 3, characterized in that: In step S201, the primary catalytic deoxygenation treatment parameters include: fixed bed continuous reactor 160-210° C., pressure 4 MPa, residence time 30-60 min.

5. The process for producing biomass fuel using biofiber according to claim 4, characterized in that: In step S202, the low temperature section alkylation treatment parameters include: substrate mass 6% nickel-based catalyst Ni / HZSM-5, temperature 210-230°C, pressure 3.5-4MPa, residence time 60-90min.

6. The process for producing biomass fuel using biofiber according to claim 5, characterized in that: In step S202, the high temperature section deoxidation refining treatment parameters include: substrate mass 8% phosphorus-modified nickel-based catalyst Ni-P / HZSM-5, temperature 250-270°C, pressure 3.5MPa, hydrogen circulation volume 200-300L / h, time 30-45min.

7. The process for producing biomass fuel using biofiber according to claim 6, characterized in that: Step S202, the specific preparation steps of the phosphorus-modified nickel-based catalyst Ni-P / HZSM-5 are as follows: S301: calcining the HZSM-5 molecular sieve, then mixing it with the ammonium nitrate solution, stirring it, filtering it, repeating the stirring process for 3 times, centrifugally filtering it, washing it to neutrality, and drying it to obtain the pretreated HZSM-5; S302: immersing the pretreated HZSM-5 prepared in step S301 in a nickel nitrate solution, stirring, centrifugally filtering, drying, and then calcining at high temperature in an air atmosphere, and then switching to introducing H2 for reduction treatment to obtain Ni / HZSM-5; S303: The Ni / HZSM-5 prepared in step S302 is mixed with a phosphoric acid solution, allowed to stand at room temperature, dried, and then calcined at high temperature in an air atmosphere, followed by hydrothermal aging in a water vapor atmosphere to obtain Ni-P / HZSM-5.

8. The process for producing biomass fuel using biofiber according to claim 7, characterized in that: In step S301, the ratio of the amount of the HZSM-5 molecular sieve to the ammonium nitrate solution is 1 g: 10-12 mL; in step S302, the ratio of the amount of the pretreated HZSM-5 to the nickel nitrate solution is 1 g: 5 mL; in step S303, the ratio of the amount of Ni / HZSM-5 to the 30 wt% phosphoric acid solution is 1 g: 0.3-0.5 mL.

9. The process for producing biomass fuel using biofiber according to claim 8, characterized in that: In step S3, the specific steps of nano-modification and fuel refining are as follows: S401: mixing carbon nanotubes and sodium lignin sulfonate in proportion, adding into deionized water, and ultrasonically treating to obtain nano slurry; S402: mixing the crude biofuel prepared in step S402 and the nano-slurry prepared in step S401 in proportion, stirring and shearing, and then homogenizing; S403: After the homogenization treatment in step S402 is completed, hydrocarbon components with a boiling range of 30 to 80° C. are collected in sections under pressure to obtain biomass fuel.

10. The process for producing biomass fuel using biofiber according to claim 9, characterized in that: In step S401, the ratio of the carbon nanotubes, sodium lignin sulfonate and deionized water is 2-3 g: 5-6 g: 100 mL; in step S402, the volume ratio of the crude biofuel and nano-slurry is 100-120:1.

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