Method for co-producing phenol-rich bio-oil and high-porosity biochar through biomass pyrolysis

Abstract

The invention discloses a method for co-producing phenol-rich bio-oil and high-porosity biochar through biomass pyrolysis. The method comprises the steps of biomass raw material source pre-conditioning, acidified biochar catalyst preparation, biomass pyrolysis catalytic reaction, inactivated acidified biochar catalyst regeneration and the like. The first biomass raw material and deionized water are subjected to a constant-temperature reaction in a pre-tempering reactor to obtain pre-tempered biomass, the second biomass raw material, an acidifying agent and the deionized water are evenly mixed and fully stirred and mixed, then drying, calcining, cleaning, grinding and screening are conducted, and the acidified biochar catalyst is obtained. And putting the pre-conditioned biomass and the acidified biochar catalyst into the second-stage fixed bed reactor, and reacting to obtain a liquid bio-oil product and a solid biochar product. According to the method, low-quality components (ash content, high-oxygen-content components and the like) in biomass are selectively removed, catalysis of the acidified biochar catalyst is coupled, a reaction path is regulated in situ, and combined preparation of the phenol-rich bio-oil and the high-porosity biochar is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of biomass pyrolysis high-value technology, and in particular to a method for co-producing phenol-rich bio-oil and high-porosity biochar by pyrolysis of biomass. Background Art

[0002] Biomass pyrolysis polygeneration technology involves a thermal conversion process that uses high temperatures under an inert atmosphere to rapidly crack organic macromolecules in biomass, releasing small volatile molecules. Upon cooling, solid biochar, liquid bio-oil, and gaseous pyrolysis gas are simultaneously produced. This technology maximizes the utilization of biomass resources and significantly reduces carbon emissions. For example, the use of biochar effectively fixes carbon, reducing atmospheric carbon dioxide levels; while the use of bio-oil and combustible gas can replace fossil fuels and reduce greenhouse gas emissions.

[0003] In existing technologies, bio-oil, biochar, and pyrolysis gas obtained through direct pyrolysis are often of low quality due to the complex composition and high oxygen content of the biomass itself. These products can only be used as low-value fuels, making resource utilization difficult and limiting the economic viability of polygeneration processes. For example, bio-oil obtained through direct pyrolysis is a dark brown liquid composed of various oxygen-containing organic compounds with a pungent odor. Its complex composition, high oxygen content, and unstable chemical properties make it unsuitable for direct chemical refining. When used as an alternative fuel, it also suffers from a low calorific value. After condensing the pyrolysis volatiles to extract the bio-oil, the remaining pyrolysis gas is a gaseous mixture composed of CO, H₂, CH₄, CO₂, and a small amount of small-molecule alkanes. Due to its high CO₂ content, its use as a gaseous fuel or synthesis gas is uneconomical. Furthermore, the mass yield and structural properties of the biochar, which is obtained through volatile analysis during the pyrolysis process and has a porous carbon skeleton, often depend on the type of feedstock, pyrolysis method, and temperature.

[0004] Traditional single-product upgrading processes, such as catalytic pyrolysis, introduce catalysts during the pyrolysis process to regulate the reaction pathway, increase the yield and selectivity of target products, and suppress the formation of byproducts, resulting in more efficient and cleaner biomass conversion. However, catalytic pyrolysis fails to fundamentally address the inherent disadvantages of biomass, such as its complex composition and high oxygen content, and can only improve the quality of a single product component. Achieving the combined quality improvement of multiphase pyrolysis products has become a major challenge in the current high-value utilization of biomass. Summary of the Invention

[0005] The purpose of the present invention is to address the defects of the existing technology and provide a method for the co-production of phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis. The method uses hydrothermal pretreatment to pre-condition the source and couples the catalytic conditioning of the acidified biochar catalyst to achieve the combined preparation of phenol-rich bio-oil and high-porosity biochar, which has the advantages of high product quality, good catalyst repeatability, and low process cost.

[0006] In order to solve the above technical problems, the present invention provides the following technical solutions:

[0007] A method for co-producing phenol-rich bio-oil and high-porosity biochar by pyrolysis of biomass, characterized by comprising the following steps:

[0008] Pre-conditioning of biomass raw materials at the source: a certain amount of the first biomass raw material and deionized water are added to a pre-conditioning reactor, mixed evenly, and the sealed pre-conditioning reactor is placed in a constant temperature reaction environment. After the reaction is completed, the reaction liquid is cooled and filtered, and the remaining solid is cleaned and dried to obtain pre-conditioned biomass;

[0009] preparing an acidified biochar catalyst: uniformly mixing a certain amount of a second biomass raw material, an acidifying agent, and deionized water, stirring and mixing thoroughly, and then drying, calcining, washing, grinding, and sieving to obtain an acidified biochar catalyst;

[0010] Biomass pyrolysis catalytic reaction: The pre-conditioned biomass and acidified biochar catalyst are respectively loaded into the pyrolysis reaction zone and catalytic reaction zone of a secondary fixed bed reactor. The temperature of the pyrolysis reaction zone and the catalytic reaction zone are 400-600°C and the atmosphere is inert gas. During the reaction, the liquid bio-oil product is condensed and collected. After the reaction, the solid biochar product is collected after the product is cooled.

[0011] Furthermore, in the biomass raw material source pre-conditioning step, the first biomass raw material is in granular or powdered form, the mass ratio of the first biomass raw material to deionized water is 1:5-1:15, the temperature of the constant temperature reaction environment is 100-250°C, the reaction time is 2-6h, the remaining solid is washed with deionized water until the filtrate is clear, the drying temperature is 105°C, and the drying time is 12h.

[0012] Furthermore, the pre-conditioning reactor is a split high-pressure reactor with a Teflon liner inside.

[0013] Furthermore, in the step of preparing the acidified biochar catalyst, the acidifier is phosphoric acid, hydrochloric acid, or acetic acid, the mass ratio of the second biomass raw material to the acidifier is 1:0.5-1:3, and the mass ratio of the second biomass raw material to deionized water is 1:10-1:20; the stirring and mixing time is 12-48 hours, the drying time is 24-48 hours, and the drying temperature is 105°C.

[0014] Furthermore, in the step of preparing the acidified biochar catalyst, the calcination process includes calcination under an inert gas atmosphere, the calcination temperature is 500-700° C., and the calcination time is 30-120 minutes.

[0015] Furthermore, the particle size of the acidified biochar catalyst is 0.1-0.3 mm.

[0016] Furthermore, in the biomass pyrolysis catalytic reaction step, the mass ratio of the pre-conditioned biomass to the acidified biochar catalyst is 1:0.5-1:2.

[0017] Furthermore, in the biomass pyrolysis catalytic reaction step, the temperatures of the pyrolysis reaction zone and the catalytic reaction zone are constant, and the reaction time is 5-20 minutes.

[0018] Furthermore, the regeneration step of the acidified biochar catalyst includes uniformly mixing a certain amount of deactivated acidified biochar catalyst, an acidifying agent and deionized water, stirring and mixing thoroughly, and then drying, calcining, washing, grinding and screening to obtain a regenerated acidified biochar catalyst.

[0019] Furthermore, the first biomass raw material includes rice husks, the second biomass raw material includes wood powder, and the inert gas includes nitrogen.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] The present invention provides a method for the co-production of phenol-rich bio-oil and high-porosity biochar by pyrolysis of biomass. By pre-conditioning the biomass raw material at the source and coupling it with an acidified biochar catalyst, the synergistic production of phenol-rich bio-oil and high-specific surface area biochar can be achieved. The advantages include high product quality, good catalyst reproducibility, and low process cost. The specific advantages are as follows:

[0022] (1) The present invention achieves the co-production of phenol-rich bio-oil and high-porosity bio-char by pyrolysis of biomass for the first time by coupling hydrothermal pretreatment source pre-conditioning with acidified biochar catalyst catalytic conditioning. The process is simple, the product value is significantly improved, and the high-value resource utilization of biomass is achieved;

[0023] (2) The method for preparing the acidified biochar catalyst used in the present invention has a simple process and mild conditions, and can be regenerated and reused by a simple method. The preparation and regeneration process of the acidified biochar catalyst does not involve the use of precious metal additives and is low-cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Schematic diagram of the process flow of biomass pyrolysis for co-production of phenol-rich bio-oil and high-porosity biochar in an embodiment of the present invention;

[0025] Figure 2 This is a scanning electron microscope image of the acidified biochar catalyst according to an embodiment of the present invention;

[0026] Figure 3 This is a GC-MS chromatogram of the liquid bio-oil prepared in an embodiment of the present invention;

[0027] Figure 4This is a scanning electron microscope image of the biochar product prepared in the embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to deepen the understanding of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings. The embodiments are only used to explain the present invention and do not constitute a limitation on the scope of protection of the present invention.

[0029] A method for co-producing phenol-rich bio-oil and high-porosity biochar by pyrolysis of biomass, comprising the following steps: Figure 1 As shown, the process includes the steps of pre-conditioning of biomass raw materials, preparation of acidified biochar catalyst, catalytic reaction of biomass pyrolysis, and regeneration of deactivated acidified biochar catalyst.

[0030] Biomass raw material source pre-conditioning step: 10g rice husks and 100g deionized water are placed in a high-pressure stainless steel reactor with a Teflon inner sleeve. After mixing evenly, tighten the reactor cover and react in a ventilated drying oven at 150°C for 4 hours. After the reaction is completed, take out the reactor and place it in an ice-water mixture to cool to room temperature. Use a filter to filter out the pre-conditioned rice husks, rinse them repeatedly with deionized water until the filtrate is clear, and dry them at 105°C for 12 hours for later use. The pre-conditioned rice husks obtained by this step selectively remove low-quality components in biomass such as rice husks, such as ash and high-oxygen components, which is beneficial to the pyrolysis catalysis in the subsequent steps, prevents premature deactivation of the catalyst, and prolongs its service life.

[0031] To prepare the acidified biochar catalyst, 20g of wood flour, 20g of phosphoric acid, and 300ml of deionized water were added to a 500mL beaker and stirred at room temperature using a magnetic stirrer for 24 hours. The mixture was then dried in a ventilated drying oven at 130°C for 36 hours. The dried mixture was calcined in a tube furnace at 500°C for 90 minutes under a nitrogen atmosphere. After cooling to room temperature, the mixture was repeatedly washed and soaked in deionized water until neutral. After drying at 105°C for 12 hours, the acidified biochar catalyst particles with a particle size of 0.1-0.3mm were ground and sieved for later use.

[0032] Biomass pyrolysis catalytic reaction steps: According to the mass ratio of biomass raw material to catalyst of 1:1, 2g of pre-tempered rice husk and 2g of acidified biochar catalyst with a particle size of 0.1-0.3mm were prepared, and pyrolysis catalytic reaction was carried out in a two-stage fixed-bed reactor.

[0033] First, load 2g of acidified biochar catalyst into the catalytic section of the reactor. Place 2g of pre-tempered rice husks in a quartz basket and place it on top of the reactor. Install the reactor piping and check the equipment for airtightness. Continue blowing nitrogen (N) into the reactor system at a rate of 200mL / min for 15 minutes to ensure complete air displacement within the reactor and prevent oxygen from igniting the biomass feedstock and catalyst.

[0034] The temperature controller panel was then adjusted to heat the reactor to the desired temperature. The temperature of both the pyrolysis and catalytic zones was set to 500°C. Once the set temperature was reached, a quartz crucible containing pre-tempered rice husks was placed into the reactor for 15 minutes. The acidified biochar catalyst, with its high mesoporous distribution and abundant surface phosphorus-containing functional groups, was able to couple with the pre-tempered rice husks, in situ regulating the reaction pathway and achieving the combined production of phenol-rich bio-oil and high-porosity biochar, demonstrating exceptionally superior directional enrichment performance.

[0035] The regeneration method for the deactivated acidified biochar catalyst is identical to its preparation method, differing only in that the deactivated acidified biochar catalyst is used instead of the wood powder feedstock. The catalyst is then mixed with phosphoric acid and deionized water, using the same material ratios and reaction conditions. The acidified biochar can be recycled through a simple regeneration process, offering promising applications.

[0036] The bio-oil produced by pyrolysis was collected by cooling in an ice-water impingement flask. Anhydrous sodium sulfate was used to absorb the water, and the oil was diluted to volume with anhydrous ethanol. The oil was then filtered through an oily filter membrane and analyzed using a gas chromatography-mass spectrometer. The biochar was weighed and collected after the reactor cooled naturally.

[0037] Figure 3 The GC-MS chromatogram of the bio-oil prepared above is shown in Figure 1. The relative content of each component in the bio-oil was calculated according to formula (1).

[0038]

[0039] Where i represents the different chemical components in bio-oil; X i represents the peak area of the corresponding component i in the GC-MS chromatogram; Y i Represents the relative content of component i.

[0040] Calculations show that the mass proportion of monophenolic substances in the collected liquid bio-oil exceeds 80%, achieving a high yield of phenol-rich products.

[0041] like Figure 4 As shown in the electron microscope scanning of the biochar product, the obtained biochar has a high porosity structure and its specific surface area exceeds 300m 2 / g, can be used directly as adsorption carbon.

[0042] The above specific implementation methods are only for illustrating the technical concept and structural features of the present invention, and the purpose is to enable relevant persons familiar with this technology to implement them accordingly. However, the above content does not limit the scope of protection of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A method for co-producing phenol-rich bio-oil and high-porosity biochar by pyrolysis of biomass, characterized in that: The following steps are involved: Pre-conditioning of biomass raw materials at the source: a certain amount of the first biomass raw material and deionized water are added to a pre-conditioning reactor, mixed evenly, and the sealed pre-conditioning reactor is placed in a constant temperature reaction environment. After the reaction is completed, the reaction liquid is cooled and filtered, and the remaining solid is cleaned and dried to obtain pre-conditioned biomass; preparing an acidified biochar catalyst: uniformly mixing a certain amount of a second biomass raw material, an acidifying agent, and deionized water, stirring and mixing thoroughly, and then drying, calcining, washing, grinding, and sieving to obtain an acidified biochar catalyst; Biomass pyrolysis catalytic reaction: The pre-conditioned biomass and acidified biochar catalyst are respectively loaded into the pyrolysis reaction zone and catalytic reaction zone of a secondary fixed bed reactor. The temperature of the pyrolysis reaction zone and the catalytic reaction zone are 400-600°C and the atmosphere is inert gas. During the reaction, the liquid bio-oil product is condensed and collected. After the reaction, the solid biochar product is collected after the product is cooled.

2. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: In the biomass raw material source pre-conditioning step, the first biomass raw material is in granular or powdered form, the mass ratio of the first biomass raw material to deionized water is 1:5-1:15, the temperature of the constant temperature reaction environment is 100-250°C, the reaction time is 2-6h, the remaining solid is washed with deionized water until the filtrate is clear, the drying temperature is 105°C, and the drying time is 12h.

3. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: The pre-conditioning reactor is a split high-pressure reactor with a Teflon lining inside.

4. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: In the step of preparing the acidified biochar catalyst, the acidifier is phosphoric acid, hydrochloric acid, or acetic acid, the mass ratio of the second biomass raw material to the acidifier is 1:0.5-1:3, and the mass ratio of the second biomass raw material to deionized water is 1:10-1:20; the stirring and mixing time is 12-48 hours, the drying time is 24-48 hours, and the drying temperature is 105°C.

5. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: In the step of preparing the acidified biochar catalyst, the calcination process includes calcination in an inert gas atmosphere at a temperature of 500-700° C. for 30-120 minutes.

6. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: The particle size of the acidified biochar catalyst is 0.1-0.3 mm.

7. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: In the biomass pyrolysis catalytic reaction step, the mass ratio of the pre-conditioned biomass to the acidified biochar catalyst is 1:0.5-1:

2.

8. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: In the biomass pyrolysis catalytic reaction step, the temperatures of the pyrolysis reaction zone and the catalytic reaction zone are constant, and the reaction time is 5-20 minutes.

9. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: The regeneration step of the acidified biochar catalyst includes uniformly mixing a certain amount of deactivated acidified biochar catalyst, an acidifying agent and deionized water, stirring and mixing thoroughly, and then drying, calcining, washing, grinding and screening to obtain a regenerated acidified biochar catalyst.

10. The method for co-producing phenol-rich bio-oil and high-porosity biochar by biomass pyrolysis according to claim 1, characterized in that: The first biomass raw material includes rice husks, the second biomass raw material includes wood powder, and the inert gas includes nitrogen.

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