CN115282947B - Method for preparing high specific surface area metal/activated carbon composite material by utilizing isosorbide residual tar - Google Patents

Abstract

The invention provides a method for preparing a high specific surface area metal/active carbon composite material by utilizing residual isosorbide tar, which comprises the steps of mixing the byproduct tar in the production process of isosorbide with urotropine, potassium nitrate and metal salt substances thereof fully for a proper time by adopting proper machinery at a proper temperature, and reducing the premixed metal salt in situ into metal by utilizing the reducibility of high-temperature carbon, thereby obtaining the metal/active carbon material with high specific surface area. The reducing agent is avoided being additionally used, so that the preparation process of the metal/active carbon material is concise and efficient, the cost is reduced, and the emission is reduced.

Description

Preparation of High Specific Surface Area Metal/Activated Carbon Composites Using Isosorbide Residual Tar Methods

technical field

The invention relates to the technical field of metal/activated carbon composite material preparation, in particular to a technical method for preparing a metal/activated carbon composite material with a high specific surface area by using residual tar produced by isosorbide.

technical background

Isosorbide is an important six-carbon platform compound derived from sugars (starch cellulose). It can be used to replace petroleum-based monomers to prepare easily biodegradable polyester, polyurethane, polyamide, polyether and other materials. It can also be used in drug synthesis. Therefore, isosorbide has great application prospects. However, in the production process of isosorbide, depending on the catalyst used, 20% to 50% of tar will be by-produced. For example, the by-product tar of isosorbide is dehydrated between sorbitol molecules and generated under the action of an acid catalyst. The intermolecular dehydration of isosorbide forms a network macromolecule. In addition, these macromolecules continue to dehydrate under the action of acid catalysts to form polymer compounds. [Xiu Yuhe, Science Bulletin, 2015, 60(16): 1443].

The texture of isosorbide by-product tar is relatively uniform and has good fluidity. Easy post-processing. Traditional biomass (such as agricultural waste, etc.) is unevenly composed, generally composed of lignin, cellulose, protein, and ash, and has poor fluidity, which is not convenient for post-processing.

How to properly handle so much by-product tar is an important factor restricting the development of isosorbide industry. The commonly used method is incineration, which wastes biomass resources on the one hand and causes secondary pollution (a large amount of CO ₂ emissions) on the other hand. There are also more complex technologies: such as thermal cracking, catalytic cracking plasma cracking technology [Li Lehao et al., Progress in Chemical Industry, 2017, 36(7): 2407]), vaporization of biomass tar. These methods are complicated in process and high in cost.

In addition, metal/activated carbon materials are widely used in the fields of organic synthesis, preparation of energy-storing catalytic materials, and the like. Generally, the "metal/activated carbon" composite material is obtained by loading the metal salt on the high specific surface activated carbon, and then reducing it with reducing gas (such as H ₂ , CH ₄ , CO, etc.) at high temperature. This method is costly and emits a lot.

Contents of the invention

The purpose of the invention is to overcome the disadvantages of high tar treatment cost, complex process and serious discharge in the prior art. A new method for the utilization of isosorbide tar with more efficient resource utilization is proposed. Another purpose is to propose a new method for the concise synthesis of high specific surface area "metal/activated carbon" materials.

The technical scheme of the present invention is: the tar produced by the isosorbide production process is mixed with functional additives and metal salts thereof in a certain proportion, and at an appropriate temperature, the materials are fully mixed with appropriate machinery for an appropriate time, so that the materials Mix well. The mixed material was subjected to a temperature-programmed treatment in a nitrogen flow. The high-temperature pyrolyzed material is naturally cooled to around room temperature in a nitrogen flow, and then the high-temperature pyrolyzed material is washed with water in an appropriate manner, so as to obtain a "metal/activated carbon" composite material with high dispersion, high specific surface area, and relatively uniform pore distribution. (M/C). This material should preferably be stored in a suitable inert medium.

Further, the functional additives are urotropine (hexamethylenetetramine) and potassium nitrate. The suitable weight ratio of urotropine to potassium nitrate is 0.3-0.6:1 (Wt).

Among them, hexatropine pyrolysis produces gaseous formaldehyde and ammonia, which promotes the generation of micropores. The formaldehyde produced cross-links with the furan ring-containing isosorbide by-product tar, which makes the carbon-forming precursor molecules larger and promotes the formation of carbon with a high specific surface area. Potassium nitrate is decomposed into potassium oxide and NO _X gas at high temperature. Promote the formation of micropores, and potassium oxide catalyzes the formation of isosorbide tar into carbon, thereby obtaining carbon with high specific surface area.

Further, salts with catalytic properties refer to general metal salts such as iron, cobalt, copper, and nickel, and salts of noble metals such as ruthenium, rhodium, palladium, iridium, platinum, and silver.

Metal salts can be carbonates, nitrates, chlorides, or organic acid salts.

Furthermore, the material weight ratio of isosorbide by-product tar to potassium nitrate and metal salt is 100: 10-30: 1-20 (wt).

Further, whether the appropriate material mixing temperature is 60-100°C.

Further, the mechanical mixing method is to use a ball mill or a wall breaking machine to mix the materials.

Wherein, the appropriate time for mechanical mixing is that different machines adopt different mixing times. The mixing time with ball milling machine is 2-4 hours; the mixing time with wall-breaking machine is 10-30 minutes.

Further, the heating procedure in the nitrogen flow is to make the material reach 650-850° C. from near room temperature at a heating rate of 2-10° C./min, and keep at the high temperature for 1-4 hours. Then cool naturally in the nitrogen flow to around room temperature and discharge, so as to obtain high-temperature pyrolysis material.

Further, the water washing of the high-temperature pyrolysis material in an appropriate way is: the weight ratio of water to high-temperature pyrolysis material is 4-10:1 (wt). And repeat the washing 3 to 5 times, and strengthen the water washing process with the help of ultrasonic waves to remove soluble impurities as much as possible.

The high-temperature pyrolysis material can also be washed with water in an appropriate way: the high-temperature pyrolysis material is packed into a packed column, and the washing water is continuously passed through the packing layer, so as to efficiently wash away the water-soluble impurities at one time.

The high specific surface area "metal/activated carbon" composite material should be preserved in an appropriate inert medium: pure water, C _{1 ~ 4} alcohol, in order to prevent the prepared M/C from being oxidized by air.

Compared with the prior art, the beneficial effects of the present invention are:

1. The scheme of the present invention uses the by-product tar in the production process of isosorbide as the carbon source prepared by the high specific surface area "metal/activated carbon" material, so that a large amount of by-product tar can be utilized as a resource, and the economic benefit of isosorbide production can be improved. reduce environmental pollution.

2. In the scheme of the present invention, the metal component precursor (i.e. metal salt) and isosorbide tar are sufficiently warmed before the temperature-programmed heat treatment to obtain a "metal/activated carbon" material in which the metal component is evenly dispersed.

3. The program of the present invention adds functional additive urotropine and potassium nitrate. Hexatropine pyrolysis produces gaseous formaldehyde and ammonia, which promotes the generation of micropores, and the generated formaldehyde cross-links with the by-product tar of isosorbide containing furan ring, which promotes the formation of high specific surface area carbon. Potassium nitrate is decomposed into potassium oxide and NO _X gas at high temperature. The gas promotes the formation of micropores, and potassium oxide catalyzes isosorbide tar into carbon, thereby obtaining carbon with high specific surface area. The synergistic effect of adding urotropine and potassium nitrate makes isosorbide tar produce activated carbon with high specific surface area under programmed temperature conditions. And the pores are relatively uniform and the distribution is relatively concentrated.

4. The present invention utilizes the reducibility of high-temperature carbon to reduce the pre-mixed metal salt into metal in situ, thereby obtaining a "metal/activated carbon" material with a high specific surface area. This avoids the additional use of reducing gases such as H ₂ , CH ₄ , and CO as reducing agents, making the preparation process of "metal/activated carbon" materials simple and efficient, reducing costs and reducing emissions.

Description of drawings

Figure 1 is a schematic diagram of the formaldehyde condensation reaction generated by the decomposition of isosorbide residual tar and urotropine under acid catalysis.

Fig. 2 is the liquid nitrogen adsorption-desorption diagram of the Pt/C composite material prepared in Example 1.

3 is a scanning electron micrograph of the Pt/C composite material prepared in Example 1.

Fig. 4 is the liquid nitrogen adsorption-detachment diagram of the Pt/C composite material prepared in Comparative Example 1.

FIG. 5 is a scanning electron micrograph of the Pt/C composite material prepared in Comparative Example 1.

Fig. 6 is the liquid nitrogen adsorption-desorption diagram of the Pt/C composite material prepared in Comparative Example 2.

7 is a scanning electron microscope image of the Pt/C composite material prepared in Comparative Example 2.

Fig. 8 is the liquid nitrogen adsorption-desorption diagram of the Pt/C composite material prepared in Comparative Example 3.

FIG. 9 is a scanning electron micrograph of the Pt/C composite material prepared in Comparative Example 3.

Analytical method:

1. Determination of material specific surface area and pore volume: liquid nitrogen adsorption method, ASAP 2010C surface pore size adsorption instrument, American Micromeritics company;

2. Analysis of metal elements on the material surface: SUPRA 5 field emission scanning electron microscope, German Zeiss Instrument Company.

3. Isosorbide production by-product Tar is a by-product of isosorbide production by acid-catalyzed dehydration. It contains 5% by weight of acid catalyst (such as zinc chloride).

Detailed ways

Embodiment 1: Preparation of high specific surface area "Pt/C"

Put 100g of isosorbide tar, 9g of urotropine, 15g of potassium nitrate, and 6g of chloroplatinic acid (containing 37.5% Pt) in a ball mill, and grind at 80°C for 3h. The ball-milled material was placed in a tube furnace, raised to 700°C at a rate of 4°C/min in a nitrogen flow, and kept at 700°C for 3 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material. After mixing 44.9g of the obtained high-temperature pyrolysis material with 250g of water, it was placed in an ultrasonic tank for 5 minutes and then filtered. This water washing operation was then repeated three times, whereby a "Pt/C" material was obtained. The obtained "Pt/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pt/C" material was 780m ² /g, and the pore volume was 0.91ml/g (see Figure 2 for liquid nitrogen adsorption-desorption). The pore size is between 2 and 20nm, mainly distributed between 4 and 10nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Pt content is 6.1%, and the potassium content is 0.14% (weight) (the scanning electron microscope picture enlarged by 10000 times is shown in FIG. 3 ). The analysis results show that high specific surface Pt/C composites are obtained.

Embodiment 2: Preparation of high specific surface area "Pd/C"

Put 100g of isosorbide tar, 5g of urotropine, 10g of potassium nitrate, and 4g of palladium nitrate (containing 41% Pd) in a ball mill, and ball mill at 60°C for 2h. The ball-milled material was placed in a tube furnace, raised to 650°C at a rate of 2°C/min in a nitrogen flow, and kept at 650°C for 4 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material. Mix 33.5g of the obtained high-temperature pyrolysis material with 134g of water, place it in an ultrasonic tank for 5 minutes, filter, and then repeat this water washing operation for 3 times to obtain a "Pd/C" material. The obtained "Pd/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pd/C" material was 582 m ² /g, and the pore volume was 0.56 ml/g. The pore size is between 2 and 25nm, mainly distributed between 3 and 12nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Pd content is 4.8%, and the potassium content is 0.21% (weight). The analysis results show that high specific surface area Pd/C composites are obtained.

Embodiment 3: Preparation of high specific surface area "Ru/C"

Put 100g of isosorbide tar, 6g of urotropine, 20g of potassium nitrate, and 3g of ruthenium trichloride (containing 37% Ru) in a ball mill, and ball mill at 60°C for 4h. The ball-milled material was placed in a tube furnace, raised to 750°C at a rate of 6°C/min in a nitrogen flow, and kept at 750°C for 2 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

Mix 44.5 g of the obtained high-temperature pyrolysis material with 360 g of water, place it in an ultrasonic tank for 5 minutes, and filter. This water washing operation was subsequently repeated 4 times to obtain a "Ru/C" material. The obtained "Ru/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the obtained "Ru/C" material had a specific surface area of 591 m ² /g and a pore volume of 0.71 ml/g. The pore size is 2-20nm, mainly distributed in 3-10nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Ru content is 5.1%, and the K content is 0.1% (weight). The analysis results show that high surface area Ru/C composites are obtained.

Embodiment 4: Preparation of high specific surface area "Rh/C"

100g of isosorbide tar, 10g of urotropine, 25g of potassium nitrate, 1g of rhodium trichloride (containing 39% Rh) were placed in a wall breaker, and stirred at 100°C for 20 minutes. The stirred material was placed in a tube furnace, raised to 750°C at a rate of 8°C/min in a nitrogen flow, and kept at 750°C for 1 hour, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

40.5 g of the obtained high-temperature pyrolysis material was mixed with 405 g of water, placed in an ultrasonic pool for 5 minutes, and then filtered. This water washing operation was subsequently repeated 4 times, whereby a "Rh/C" material was obtained. The obtained "Rh/C" material was placed in purified water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the obtained "Rh/C" material had a specific surface area of 852 m ² /g and a pore volume of 0.98 ml/g. The pore size is between 2 and 18nm, mainly distributed between 3 and 9nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the Rh content on the surface is 1.5%, and the K content is 0.12% (by weight). The analysis results show that Rh/C composites with high specific surface area are obtained.

Embodiment 5: Preparation of high specific surface area "Ag/C"

100g of isosorbide tar, 12g of urotropine, 30g of potassium nitrate, and 10g of silver nitrate (containing 63% Ag) were placed in a wall breaker and stirred at 100°C for 20 minutes. The stirred material was placed in a tube furnace, raised to 650°C at a rate of 5°C/min in a nitrogen flow, and kept at 650°C for 4 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

48.2 g of the obtained high-temperature pyrolysis material was mixed with 300 g of water, placed in an ultrasonic pool for 5 minutes, and then filtered. Subsequently, such a water washing operation was repeated 5 times, whereby an "Ag/C" material was obtained. The obtained "Ag/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Ag/C" material was 983m ² /g, and the pore volume was 1.09ml/g. The pore size is between 2 and 25nm, mainly distributed between 3 and 11nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Ag content is 15.7%, and the K content is 0.17% (weight). The analysis results show that high specific surface Ag/C composites are obtained.

Embodiment 6: Preparation of high specific surface area "Ir/C"

100g isosorbide tar, 10g urotropine, 20g potassium nitrate, 3g chloroiridic acid (containing 39% Ir) were placed in a wall breaker, and stirred at 100°C for 10 minutes. The stirred material was placed in a tube furnace, raised to 800°C at a rate of 10°C/min in a nitrogen flow, and kept at 800°C for 4 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

39.5 g of the obtained high-temperature pyrolysis material was mixed with 400 g of water, placed in an ultrasonic tank for 5 minutes, and then filtered. This water washing operation was subsequently repeated 5 times, whereby an "Ir/C" material was obtained. The obtained "Ir/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Ir/C" material was 703 m ² /g, and the pore volume was 0.74 ml/g. The pore diameter is 2-22nm, mainly distributed in 3-9nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Ir content is 4.7%, and the K content is 0.09% (weight). The analysis results show that high specific surface Ir/C composites are obtained.

Embodiment 7: Preparation of high specific surface area "Fe/C"

100g isosorbide tar, 10g urotropine, 20g potassium nitrate, 20g ferric nitrate (containing 13.8% Fe) were placed in a wall breaker, and stirred at 80°C for 20 minutes. The stirred material was placed in a tube furnace, and in a nitrogen flow, the temperature was raised to 850°C at a rate of 10°C/min, and kept at 850°C for 1 hour. Then, it is naturally cooled to around room temperature in a nitrogen flow, and the material is taken out to obtain a high-temperature pyrolysis material.

41g of the obtained high-temperature pyrolysis material was loaded into a glass filter column with an inner diameter of 20cm, and 250g of water was dripped into the pyrolysis material within 1 hour to continuously wash the pyrolysis material, thereby obtaining the "Fe/C" material. The obtained "Fe/C" material was placed in methanol and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pd/C" material was 866 m ² /g, and the pore volume was 0.96 ml/g. The pore size is 2-20nm, mainly distributed in 3-10nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Fe content is 9.3%, and the K content is 0.08% (weight). The analysis results show that high specific surface Fe/C composites are obtained.

Embodiment 8: Preparation of high specific surface area "Co/C"

Put 100g of isosorbide tar, 15g of urotropine, 30g of potassium nitrate, and 10g of cobalt succinate (containing 33% Co) in a wall breaker, and stir at 100°C for 20 minutes. The stirred material was placed in a tube furnace, raised to 750°C at a rate of 5°C/min in a nitrogen flow, and kept at 750°C for 3 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

46.6g of the obtained high-temperature pyrolysis material was loaded into a glass filter column with an inner diameter of 20cm, and 250g of water was dripped into the pyrolysis material within 1 hour to continuously wash the pyrolysis material, thereby obtaining a "Co/C" material. The obtained "Co/C" material was placed in ethanol and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the obtained "Co/C" material had a specific surface area of 1106 m ² /g and a pore volume of 1.15 ml/g. The pore size is between 2 and 20nm, mainly distributed between 3 and 11nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Co content is 9.7%, and the K content is 0.11% (weight). The analysis results show that high specific surface Co/C composites are obtained.

Embodiment 9: Preparation of high specific surface area "Cu/C"

Put 100g of isosorbide tar, 8g of urotropine, 20g of potassium nitrate, and 5g of basic copper carbonate (containing 57% Cu) in a ball mill, and grind at 80°C for 4h. The ball-milled material was placed in a tube furnace, raised to 650°C at a rate of 5°C/min in a nitrogen flow, and kept at 650°C for 2 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

Mix 42.0 g of the obtained high-temperature pyrolysis material with 252 g of water, place it in an ultrasonic tank for 5 minutes, filter, and then repeat this water washing operation 4 times, thereby obtaining a "Cu/C" material. The obtained "Cu/C" material was placed in isopropanol and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Cu/C" material was 772 m ² /g, and the pore volume was 0.83 ml/g. The pore size is between 2 and 25nm, mainly distributed between 3 and 10nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Cu content is 8.8%, and the K content is 0.18% (weight). The analysis results show that Cu/C composites with high surface area are obtained.

Embodiment 10: Preparation of high specific surface area "Ni/C"

Put 100g of isosorbide tar, 10g of urotropine, 20g of potassium nitrite, and 20g of hydrated nickel nitrate (containing 20% Ni) in a ball mill, and grind at 80°C for 4h. The ball-milled material was placed in a tube furnace, raised to 800°C at a rate of 8°C/min in a nitrogen flow, and kept at 800°C for 2 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

45.7g of the obtained high-temperature pyrolysis material was mixed with 275g of water, placed in an ultrasonic tank for 5 minutes, and filtered. This water washing operation was subsequently repeated 4 times, thereby obtaining a "Ni/C" material. The obtained "Ni/C" material was placed in n-butanol and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Ni/C" material was 845 m ² /g, and the pore volume was 1.1 ml/g. The pore size is 2-20nm, mainly distributed in 3-10nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Ni content is 9.7%, and the K content is 0.19% (weight). The analysis results show that high specific surface Ni/C composites are obtained.

Comparative Example 1: Preparation of "Pt/C" composite material without adding functional additives

100 g of isosorbide tar and 6 g of chloroplatinic acid (containing 37.5% Pt) were placed in a ball mill and ground at 80° C. for 3 h. The ball-milled material was placed in a tube furnace, raised to 700°C at a rate of 4°C/min in a nitrogen flow, and kept at 700°C for 3 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

The obtained 34.6g of high-temperature pyrolysis material was mixed with 250g of water, placed in an ultrasonic pool for 5 minutes, and then filtered. This water washing operation was then repeated three times, whereby a "Pt/C" material was obtained. The obtained "Pt/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pt/C" material was 68m ² /g, and the pore volume was 0.31ml/g (see Figure 4 for liquid nitrogen adsorption-desorption). The pore size is distributed between 2 and 90nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the Pt content on the surface is 4.8% (by weight) (the scanning electron microscope image enlarged by 10000 times is shown in FIG. 5 ).

Compared with Example 1 of the present invention, this result does not add urotropine and potassium nitrate, does not have its decomposition, gasification, pore-causing and cross-linking effects, and the carbonization rate of isosorbide tar is low, resulting in the prepared Pt/C composite material The specific surface area is very small; in addition, it can be seen from the liquid nitrogen adsorption-desorption curve that the pore distribution of the material prepared without adding functional additives is very wide.

Comparative Example 2: Preparation of "Pt/C" composite material only by adding potassium nitrate

Put 100g of isosorbide tar, 24g of KNO ₃ , and 6g of chloroplatinic acid (containing 37.5% Pt) in a ball mill, and grind at 80°C for 3h. The ball-milled material was placed in a tube furnace, raised to 700°C at a rate of 4°C/min in a nitrogen flow, and kept at 700°C for 3 hours, then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

42.2g of the obtained high-temperature pyrolysis material was mixed with 250g of water, placed in an ultrasonic tank for 5 minutes, and filtered. This water washing operation was then repeated three times, whereby a "Pt/C" material was obtained. The obtained "Pt/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pt/C" material was 235m ² /g, and the pore volume was 0.43ml/g (see Figure 6 for liquid nitrogen adsorption-desorption). The pore size is between 1 and 45nm, mainly distributed between 4 and 15nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Pt content is 5.3% (by weight) (the scanning electron microscope picture enlarged by 10000 times is shown in FIG. 7 ).

This result is compared with Example 1 of the present invention, only adding potassium nitrate, although there is the catalytic charring effect of potassium oxide, but there is no decomposing pore-causing and cross-linking effect of urotropine, resulting in the prepared Pt/C composite material ratio The surface area is relatively small.

Comparative Example 3: Preparation of "Pt/C" composite material only by adding urotropine

Put 100 g of isosorbide tar, 24 g of urotropine, and 6 g of chloroplatinic acid (containing 37.5% Pt) in a ball mill, and grind at 80° C. for 3 h. The ball-milled material was placed in a tube furnace, and in a nitrogen flow, the temperature was raised to 700°C at a rate of 4°C/min, and kept at 700°C for 3 hours, and then naturally cooled to around room temperature in a nitrogen flow, and the material was taken out to obtain High temperature pyrolysis material.

Mix 38.8g of the obtained high-temperature pyrolysis material with 250g of water, place it in an ultrasonic tank for 5 minutes, and filter. This water washing operation was then repeated three times, whereby a "Pt/C" material was obtained. The obtained "Pt/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pt/C" material was 188m ² /g, and the pore volume was 0.21ml/g (see Figure 8 for liquid nitrogen adsorption-desorption). The pore size is between 1 and 25nm, mainly distributed between 2 and 12nm. According to the scanning electron microscope surface energy spectrum analysis (SEM-EDS), the surface Pt content is 5.7% (by weight) (the scanning electron microscope picture enlarged by 10000 times is shown in FIG. 9 ).

Compared with Example 1 of the present invention, this result only adds urotropine, although there is decomposition of urotropine and cross-linking effect, but there is no catalytic charring effect of potassium oxide, resulting in the prepared Pt/C composite The specific surface area of the material is relatively small.

By the comparison of comparative example 2 and comparative example 3 and example 1 of the present invention, it can be seen that adding urotropine and potassium nitrate produces a synergistic effect, so that isosorbide tar generates the specific surface area of gac under the temperature-programmed condition. improve.

Comparative example 4: Preparation of "Pt/C" composite material by _H2 reduction method

[Reference: Li Xiaoyun et al. Acta Catalytica Sinica, 2008, 29(3): 259]

50g of coconut shell activated carbon (Jiangsu Youhuada Environmental Protection Materials Co., Ltd., specific surface area 960m ² /g, pore volume 0.68ml/g) was oxidized with 250ml of _HNO3 aqueous solution with a concentration of 5mol/L at 90°C for 6h, filtered and washed Finally, it was dried at 60°C to obtain activated coconut shell activated carbon.

Take 6g of chloroplatinic acid (containing 37.5% Pt) and dissolve it in 250ml of purified water. The activated coconut shell activated carbon was added to the chloroplatinic acid solution and stirred at room temperature for 12h. Filter with suction, and dry the solid at 80°C.

The dried material was placed in a tube furnace, raised to 400°C at a rate of 4°C/min in 400ml/min _H2 flow, and kept at 400°C for 2h, then naturally cooled in _H2 flow To near room temperature, take out the material. The obtained "Pt/C" material was placed in pure water and sealed for storage.

Through liquid nitrogen adsorption analysis, it was determined that the specific surface area of the obtained "Pt/C" material was 945 m ² /g, and the pore volume was 0.63 ml/g. The Pt content on the surface is 5.4% (by weight) according to the surface energy spectrum analysis (SEM-EDS) of the scanning electron microscope.

This result is compared with embodiment 1 of the present invention, and coconut shell activated carbon activation process and Pt loading process all produce a large amount of waste liquid, and reduction process consumes _H gas. The discharge of three wastes in the whole process is relatively large. And the operation process is complicated.

Claims (5)

1. a method utilizing isosorbide byproduct tar to prepare high specific surface area metal/activated carbon composite material, is characterized in that: Isosorbide by-product tar is mechanically mixed with functional additives and metal salts. The mechanical mixing temperature is 60~100°C. After mixing, the mixed material is subjected to high-temperature pyrolysis in a nitrogen flow. The temperature rise treatment procedure in a nitrogen flow is With a heating rate of 2-10°C/min, the material is raised from room temperature to 650-850°C, and kept at high temperature for 1-4 hours, and then naturally cooled to room temperature in nitrogen flow to obtain high-temperature pyrolysis material. After pyrolysis Cool naturally in nitrogen flow, wash with water, obtain metal/activated carbon composite material, preserve in inert medium; The functional additive is composed of urotropine and potassium nitrate; the weight ratio of urotropine to potassium nitrate is 0.3~0.6:1; the metal salt is iron, cobalt, copper, nickel, ruthenium, rhodium, palladium, iridium, platinum or one or more of silver metal salts; the weight ratio of isosorbide by-product tar to potassium nitrate and metal salt is 100: 10~30: 1~20; isosorbide production by-product tar is dehydrated by acid catalysis A by-product of the production of isosorbide, which contains 5% by weight of the acid catalyst zinc chloride. 2. utilize isosorbide byproduct tar according to claim 1 to prepare the method for high specific surface area metal/activated carbon composite material, it is characterized in that: metal salt is carbonate, nitrate, chloride salt or organic acid salt. 3. according to claim 1, utilize isosorbide by-product tar to prepare the method for high specific surface area metal/activated carbon composite material, it is characterized in that: mechanical mixing mode is to mix materials with ball milling machinery or wall breaking machinery. 4. utilize isosorbide by-product tar according to claim 1 to prepare the method for high specific surface area metal/activated carbon composite material, it is characterized in that: be 2～4h with ball mill mechanical mixing time; Be 10 with broken wall mechanical mixing time ~30 minutes. 5. according to claim 1, utilize isosorbide byproduct tar to prepare the method for high specific surface area metal/activated carbon composite material, it is characterized in that: washing refers to the weight ratio 4～10: 1 of water and high-temperature pyrolysis material, repeats Wash 3 to 5 times and use ultrasonic to strengthen the water washing process, or put high-temperature pyrolysis material into the packed column, let the washing water pass through the packing layer continuously, and wash away the water-soluble impurities.