A high-strength carbonized wood material and preparation method thereof

Abstract

The present invention relates to the technical field of carbonized wood, and specifically to a high-strength carbonized wood material and a preparation method thereof. The preparation method provided by the present application comprises placing a dried wood block into a boiling mixed solution of NaOH and Na2SO3, utilizing chemical treatment to partially remove lignin and hemicellulose from the wood, causing partial cell walls in the wood to collapse, and then compressing highly arranged cellulose nanofibers under external pressure in a vacuum environment to completely densify the wood, thereby improving the mechanical properties of the carbonized wood, ensuring the mechanical strength of the carbonized wood produced from fast-growing forests, and improving the quality of environmentally friendly materials. At the same time, the chemical reagents NaOH, Na2SO3, and H2O2 used in the present application are all commonly used chemical reagents with low cost and easy to handle and dispose of to achieve pollution-free operation. The sample processing process and steps are simple and easy to operate, with high repeatability, and are easy to carry out large-scale industrial production and manufacturing. The high-strength carbonized wood material provided by the present application has high mechanical properties and can better meet application performance requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of carbonized wood, in particular to a high-strength carbonized wood material and a preparation method thereof. Background Art

[0002] Wood carbon (WC) is a carbon material with a wide range of raw materials, low cost, and simple preparation methods. It is very popular both in industry and at the forefront of materials science research. For example, in the field of catalytic materials, Wang et al. uniformly loaded Ni nanoparticles on the long and straight mesoporous channels of wood carbon to construct a low-tortuosity high-performance flow reactor for the conversion of biomass tar, with excellent results (YG Wang, GW Sun, JQ Dai, G. Chen, J. Morgenstern, YB Wang, SF Kang, MW Zhu, S. Das, LFCui, and LH Hu, Adv. Mater. 2017, 29, 1604257.); Zhang et al. used wood carbon to construct a Ni-Fe-Ce hydrotalcite-derived structured reactor, achieving a toluene conversion rate of over 98% and excellent stability (SQ Zhang, WP Hu, XA Xiang, HY Xu, ZF Shen, YN Liu, QN Xia, ZG Ge, YG Wang, X. Li, Fuel Processing Technology, 2022, 226, 107077.); Xu et al. also used a sol-gel method to grow mesoporous nickel-silica nanocomposites (Ni-SiO2@C) in carbonized wood microchannels, which also performed well in tar reforming catalytic reactions (HYXu, ZF Shen, SQ Zhang, G. Chen, H. Pan, ZG Ge, Z. Zheng, YQ Wang, YG Wang, X. Li, Journal of Colloid and Interface Science, 2021, 599, 650-660.). The mesoporous channels of carbonized wood facilitate the high dispersion of catalytically active nanoparticles such as Ni, effectively preventing Ni from coking.

[0003] However, from an economic and resource perspective, the primary raw material for carbonized wood comes from fast-growing forests with short growth cycles. Fast-growing forest wood is a recyclable engineering material. Utilizing my country's abundant fast-growing forest wood resources to develop environmentally friendly and recyclable wood has significant social significance for energy conservation and emission reduction, and for building a resource-conserving and environmentally friendly economic cycle. However, the mechanical properties (strength and toughness) of carbonized wood produced from fast-growing forest wood are unsatisfactory for many advanced engineering structures and applications.

[0004] Therefore, the development of high-strength carbonized wood is urgent. Summary of the Invention

[0005] To solve the above problems, the present invention provides a high-strength carbonized wood material and a preparation method thereof. Chemical treatment is used to partially remove lignin and hemicellulose from the wood, causing part of the cell wall to collapse. The wood is then completely densified through external pressure compression in a vacuum environment to produce carbonized wood with generally improved mechanical properties, thereby improving the quality of environmentally friendly materials.

[0006] The technical solution adopted in the present invention is:

[0007] A method for preparing a high-strength carbonized wood material comprises the following steps:

[0008] a. Cut the logs into cylindrical wood blocks along the growth direction and place the wood blocks into an air blower for drying;

[0009] b. Heat-treating the wood blocks dried in step a in a boiling mixed solution of NaOH and Na2SO3 to remove some lignin and hemicellulose, then repeatedly washing the wood blocks with hot deionized water and soaking and washing with H2O2 to completely remove residual NaOH and Na2SO3;

[0010] c. Place the wood block treated in step b into a vacuum drying oven for drying, then place the dried wood block into a tube furnace for high-temperature carbonization treatment under a nitrogen atmosphere to obtain a high-strength carbonized wood material.

[0011] As a further solution, in step a, the cylindrical wooden block has a length of 15 mm and a diameter of 10 mm.

[0012] As a further solution, in step a, the temperature of the wood block in the blast drying oven is 60-80° C., and the drying time is 12-24 hours.

[0013] As a further solution, in step b, the concentration of NaOH in the mixed solution is 2.5 mol / L, the concentration of Na2SO3 is 0.4 mol / L, and the heat treatment time is 8 to 12 h.

[0014] As a further solution, the temperature of the deionized water used to wash the wood in step b is 80-100° C., and the number of washing times is 3-5 times.

[0015] As a further solution, the concentration of the H2O2 solution in step b is 2.5 mol / L, and the soaking time is 12 to 16 hours.

[0016] As a further solution, in step c, the temperature of the vacuum drying oven is 50-60° C., the drying time is 12-24 h, and the vacuum degree is -0.08-0.10 MPa.

[0017] As a further solution, in step c, the carbonization temperature in the tubular furnace under nitrogen atmosphere is 300-800° C., and the time is 3-5 hours.

[0018] Based on the same inventive concept, the present application also provides a high-strength carbonized wood material prepared by the above-mentioned preparation method.

[0019] The beneficial effects of the present invention are as follows:

[0020] 1. The preparation method provided by the present application comprises placing a dried wood block into a boiling mixed solution of NaOH and Na2SO3, using chemical treatment to partially remove lignin and hemicellulose from the wood, causing partial cell wall collapse in the wood, and then compressing the highly aligned cellulose nanofibers under external pressure in a vacuum environment to completely densify the wood, thereby generally improving the mechanical properties of the produced carbonized wood, thereby ensuring the mechanical strength of the carbonized wood produced from fast-growing forests and improving the quality of environmentally friendly materials. At the same time, the chemical reagents NaOH, Na2SO3 and H2O2 used in the present application are all commonly used chemical reagents with low cost and easy to handle and dispose of without pollution. In addition, the preparation method provided by the present application has a simple process, and the sample processing process and steps are simple and easy to operate, with high repeatability, and is easy to carry out large-scale industrial production.

[0021] 2. The high-strength carbonized wood material provided in this application has high mechanical properties, can better meet application performance requirements, and has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Photos of the camphor wood logs and chemically treated camphor wood of the present application, as well as the corresponding carbonized wood and high-strength carbonized wood after carbonization at 300°C, where A1 is the camphor wood log, A2 is the carbonized camphor wood log, B1 is the treated camphor wood, and B2 is the carbonized camphor wood after treatment;

[0023] Figure 2 This is a strength comparison chart of the high-strength carbonized wood obtained in Examples 1, 2, and 3 of the present application and the corresponding log carbonized wood, wherein a1-log carbonized wood of Example 1, a2-high-strength carbonized wood of Example 1, b1-log carbonized wood of Example 2, b2-high-strength carbonized wood of Example 2, c1-log carbonized wood of Example 3, c2-high-strength carbonized wood of Example 3;

[0024] Figure 3This is a strength comparison chart of the high-strength carbonized wood obtained in Examples 4, 5 and 6 of the present application and the corresponding log carbonized wood, wherein d1 is the log carbonized wood of Example 4, d2 is the high-strength carbonized wood of Example 4, e1 is the log carbonized wood of Example 5, e2 is the high-strength carbonized wood of Example 5, f1 is the log carbonized wood of Example 6, and f2 is the high-strength carbonized wood of Example 6. DETAILED DESCRIPTION

[0025] To facilitate understanding of the present invention, the present invention will be described more fully below through examples, with preferred embodiments of the present invention provided below. However, the present invention can be implemented in a variety of different forms and is not limited to the embodiments described herein. Any other embodiments obtained by modifying or equivalently replacing the technical solution of the present invention without inventive results are within the scope of protection of the present invention.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art in the art of the present invention. The terms used in the specification of the present invention are only for describing specific embodiments and are not intended to limit the present invention.

[0027] The numerical values disclosed in the embodiments of the present invention are approximate values, not definite values. Where errors or experimental conditions permit, all values within the error range may be included without being limited to the specific numerical values disclosed in the embodiments of the present invention.

[0028] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0029] Example 1

[0030] This embodiment provides a method for preparing camphor wood-based high-strength carbonized wood, comprising the following steps:

[0031] Step 1: Form the camphor wood logs into cylinders with a length of about 15 mm and a diameter of 10 mm along the growth direction, and then dry the camphor wood logs in a forced air drying oven at 80° C. for 12 hours;

[0032] Step 2: Place the dried camphor wood logs in step 1 into a beaker and pour in about 200 ml of a mixed solution of 2.5 mol / L NaOH and 0.4 mol / L Na2SO3. Keep the oil bath boiling for 8 hours. Then, wash the camphor wood with 90°C deionized water three times to eliminate the floating color. Then, soak the camphor wood in a 2.5 mol / L H2O2 solution for 16 hours until the floating color is basically faded.

[0033] Step 3: vacuum-dry the camphor wood treated in step 2 for 24 hours at a drying temperature of 50° C. and a drying vacuum degree of -0.08 MPa; then carbonize the wood in a tubular furnace at 300° C. for 5 hours under an inert atmosphere, and carbonize and calcine to prepare camphor wood-based high-strength carbonized wood.

[0034] Performance test: The camphor wood logs were carbonized under the same carbonization conditions as in Example 1 to obtain carbonized camphor wood logs. Then, the carbonized camphor wood logs and the high-strength carbonized wood obtained in Example 1 were placed on a press for pressure testing and comparison. The press model was Edelburg HP-1k.

[0035] Example 2

[0036] This embodiment provides a method for preparing camphor wood-based high-strength carbonized wood, comprising the following steps:

[0037] Step 1: Form the camphor wood logs into cylinders with a length of about 15 mm and a diameter of 10 mm along the growth direction, and then dry the camphor wood logs in a forced air drying oven at 60° C. for 16 hours;

[0038] Step 2: Place the dried camphor wood logs in step 1 into a beaker and pour in about 200 ml of a mixed solution of 2.5 mol / L NaOH and 0.4 mol / L Na2SO3. Keep the oil bath boiling for 10 hours. Then, wash the camphor wood with 90°C deionized water four times to eliminate the floating color. Then, soak the camphor wood in a 2.5 mol / L H2O2 solution for 16 hours until the floating color is basically faded.

[0039] Step 3: vacuum-dry the camphor wood treated in step 2 for 16 hours at a drying temperature of 50°C and a drying vacuum degree of -0.08MPa; then carbonize the wood in a tubular furnace at 500°C for 3 hours under an inert atmosphere, and carbonize and calcine to prepare camphor wood-based high-strength carbonized wood.

[0040] Performance test: The camphor wood logs were carbonized under the same carbonization conditions as in Example 2 to obtain carbonized camphor wood logs. Then, the carbonized camphor wood logs and the high-strength carbonized wood obtained in Example 2 were placed on a press for pressure testing and comparison. The press model was Edelburg HP-1k.

[0041] Example 3

[0042] This embodiment provides a method for preparing camphor wood-based high-strength carbonized wood, comprising the following steps:

[0043] Step 1: Form the camphor wood logs into cylinders with a length of about 15 mm and a diameter of 10 mm along the growth direction, and then dry the camphor wood logs in a forced air drying oven at 60° C. for 24 hours;

[0044] Step 2: Place the dried camphor wood logs in step 1 into a beaker and pour in about 200 ml of a mixed solution of 2.5 mol / L NaOH and 0.4 mol / L Na2SO3. Keep the oil bath boiling for 10 hours. Then, wash the camphor wood with 80°C deionized water 5 times to eliminate the floating color. Then, soak the camphor wood in a 2.5 mol / L H2O2 solution for 16 hours until the floating color is basically faded.

[0045] Step 3: vacuum-dry the camphor wood treated in step 2 for 16 hours at a drying temperature of 55°C and a drying vacuum degree of -0.09 MPa; then carbonize the wood in a tubular furnace at 800°C for 3 hours under an inert atmosphere, and carbonize and calcine to prepare camphor wood-based high-strength carbonized wood.

[0046] Performance test: The camphor wood logs were carbonized under the same carbonization conditions as in Example 3 to obtain carbonized camphor wood logs, which were then placed on a press with the high-strength carbonized wood obtained in Example 1 for pressure testing and comparison. The press model was Adberg HP-1k.

[0047] Example 4

[0048] This embodiment provides a method for preparing pine-based high-strength carbonized wood, comprising the following steps:

[0049] Step 1: Shape the pine logs into cylinders with a length of about 15 mm and a diameter of 10 mm along the growth direction; then dry the pine logs in a forced air drying oven at 80°C for 12 hours;

[0050] Step 2: Place the dried pine logs from step 1 into a beaker and pour in about 200 ml of a mixed solution of 2.5 mol / L NaOH and 0.4 mol / L Na2SO3. Keep boiling in an oil bath for 10 hours. Then, wash the pine logs with 100°C deionized water five times until the floating color disappears. Then, soak the pine logs in a 2.5 mol / L H2O2 solution for 16 hours until the floating color is basically faded.

[0051] Step 3: The pine wood treated in step 2 is vacuum dried at 50°C and a vacuum degree of -0.09 MPa for 24 hours; then the wood is carbonized in a tubular furnace at 300°C for 4 hours under an inert atmosphere to prepare pine-based high-strength carbonized wood through carbonization and calcination.

[0052] Performance test: The pine logs were carbonized under the same carbonization conditions as in Example 4 to obtain pine log carbonized wood, which was then placed on a press machine with the model of Edelburg HP-1k for pressure testing and comparison with the high-strength carbonized wood obtained in Example 4.

[0053] Example 5

[0054] This embodiment provides a method for preparing paulownia-based high-strength carbonized wood, comprising the following steps:

[0055] Step 1: Shape the paulownia logs into cylinders with a length of about 15 mm and a diameter of 10 mm along the growth direction; then dry the paulownia logs in a forced air drying oven at 70° C. for 16 hours;

[0056] Step 2: Place the dried paulownia logs from Step 1 into a beaker and pour in approximately 200 ml of a mixed solution of 2.5 mol / L NaOH and 0.4 mol / L Na2SO3, and keep boiling in an oil bath for 8 hours; then wash the paulownia logs with 90°C deionized water four times until the floating color disappears, and then soak them in a 2.5 mol / L H2O2 solution for 12 hours until the floating color basically fades;

[0057] Step 3: vacuum-dry the paulownia wood treated in step 2 for 16 hours at a drying temperature of 55° C. and a vacuum degree of -0.10 MPa; then carbonize the wood in a tubular furnace at 300° C. for 5 hours under an inert atmosphere, and carbonize and calcine to prepare paulownia-based highly reinforced carbonized wood.

[0058] Performance test: The paulownia logs were carbonized under the same carbonization conditions as in Example 5 to obtain paulownia log carbonized wood, which was then placed on a press machine with the model of the Adberg HP-1k for pressure testing and comparison with the high-strength carbonized wood obtained in Example 5.

[0059] Example 6

[0060] This embodiment provides a method for preparing maple-based high-strength carbonized wood, comprising the following steps:

[0061] Step 1: Shape the maple log into a cylinder with a length of about 15 mm and a diameter of 10 mm along the growth direction, and then dry the maple log in a forced air drying oven at 60°C for 24 hours;

[0062] Step 2: Place the dried paulownia logs from Step 1 into a beaker and pour in approximately 200 ml of a mixed solution of 2.5 mol / L NaOH and 0.4 mol / L Na2SO3. Keep boiling in an oil bath for 12 hours. Then, wash the maple logs with 95°C deionized water four times until the floating color disappears. Then, soak the maple logs in a 2.5 mol / L H2O2 solution for 14 hours until the floating color is substantially faded.

[0063] Step 3: vacuum-dry the maple wood treated in step 2 for 12 hours at a drying temperature of 60° C. and a vacuum degree of -0.08 MPa; then carbonize the wood in a tubular furnace at 300° C. for 5 hours under an inert atmosphere, and carbonize and calcine to prepare maple-based highly reinforced carbonized wood.

[0064] Performance test: The maple logs were carbonized under the same carbonization conditions as in Example 6 to obtain carbonized maple logs. The carbonized maple logs and the high-strength carbonized wood obtained in Example 6 were then placed on a press machine, the model of which was the Adberg HP-1k, for pressure testing and comparison.

[0065] In summary, see Figure 1 As shown, after the logs are chemically treated by the preparation method provided by the present application, the diameter of the wood is significantly reduced. This can be seen because the present application uses chemical treatment to partially remove lignin and hemicellulose from the wood, causing part of the cell walls in the wood to collapse, thereby reducing the diameter of the logs. Subsequently, the high-strength carbonized wood treated by the present application is further reduced in diameter, denser, and has greatly enhanced mechanical strength compared to the carbonized wood directly treated from the logs, which can better meet application requirements.

[0066] Specifically, see Figure 2-3 As shown, the high-strength carbonized wood processed by the present application has generally improved mechanical properties compared with the carbonized wood directly processed from logs, thereby ensuring the mechanical strength of the carbonized wood produced from fast-growing forests and improving the quality of environmentally friendly materials.

[0067] At the same time, the chemical reagents NaOH, Na2SO3 and H2O2 used in this application are all commonly used chemical reagents with low cost and easy to handle and dispose of without pollution. The preparation method provided in this application has a simple process, and the sample processing process and steps are simple and easy to operate, with high repeatability, and is easy to carry out large-scale industrial production.

[0068] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a high-strength carbonized wood material, characterized in that: The steps include: a. Cut the logs into cylindrical wood blocks along the growth direction and place the wood blocks into an air blower for drying; b. Heat-treating the wood blocks dried in step a in a boiling mixed solution of NaOH and Na2SO3 to remove some lignin and hemicellulose, then repeatedly washing the wood blocks with hot deionized water and soaking and washing with H2O2 to completely remove residual NaOH and Na2SO3; c. Place the wood block treated in step b in a vacuum drying oven for drying at a temperature of 50 to 60° C., a drying time of 12 to 24 hours, and a vacuum degree of -0.08 to -0.10 MPa. Subsequently, place the dried wood block in a tubular furnace for high-temperature carbonization treatment under a nitrogen atmosphere to obtain a high-strength carbonized wood material.

2. The method for preparing high-strength carbonized wood material according to claim 1, characterized in that: In step a, the cylindrical wooden block has a length of 15 mm and a diameter of 10 mm.

3. The method for preparing high-strength carbonized wood material according to claim 1, characterized in that: In step a, the temperature of the wood block in the blast drying oven is 60 to 80° C., and the drying time is 12 to 24 hours.

4. The method for preparing high-strength carbonized wood material according to claim 1, characterized in that: In step b, the concentration of NaOH in the mixed solution is 2.5 mol / L, the concentration of Na2SO3 is 0.4 mol / L, and the heat treatment time is 8 to 12 h.

5. The method for preparing high-strength carbonized wood material according to claim 1, characterized in that: The temperature of the deionized water used for washing the wood in step b is 80-100° C., and the number of washing times is 3-5 times.

6. The method for preparing high-strength carbonized wood material according to claim 1, characterized in that: The concentration of the H2O2 solution in step b is 2.5 mol / L, and the soaking time is 12 to 16 hours.

7. The method for preparing high-strength carbonized wood material according to claim 1, characterized in that: In step c, the carbonization temperature in the tubular furnace under nitrogen atmosphere is 300-800° C. and the time is 3-5 hours.

8. A high-strength carbonized wood material prepared by the preparation method according to any one of claims 1 to 7.

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