Method for utilizing spent petroleum catalytic cracking catalyst, microwave absorbing composite material

Abstract

The application discloses a utilization method of waste oil catalytic cracking catalyst and a microwave absorption composite material prepared by the method. The waste FCC catalyst is used as a base body, phenolic resin is added as a binder, carbon black is uniformly distributed on the surface of the waste FCC catalyst through ball milling, mullite is generated through sintering, and silicon carbide is generated through a carbon thermal reduction reaction, so that the composite material has good impedance matching. The carbon black forms an electrically conductive network in the composite material, and the dielectric loss of the composite material is improved. The obtained composite material has good impedance matching and dielectric loss, and exhibits excellent electromagnetic wave attenuation capability. Heavy metals V2O5 and NiO in the waste FCC catalyst are converted into AlV2O4 and NiAl2O4, so that the harmful heavy metal oxides are harmlessly treated. The application uses the waste FCC catalyst and carbon black as main raw materials to prepare a high-efficiency wave absorption material, solves the environmental pollution problem caused by directly discarding the waste FCC catalyst, and realizes resource utilization of the waste FCC catalyst.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of solid waste resource utilization, and particularly relates to a utilization method of waste petroleum catalytic cracking catalyst and a microwave absorption composite material prepared by the method. BACKGROUND

[0002] Petroleum catalytic cracking (FCC) catalyst is one of the most widely used catalysts in the gasoline refining industry, and 80% of the gasoline in China is produced by using it. However, due to the influence of heavy metals and high temperature and high pressure reaction conditions, the catalyst gradually deactivates, and then waste FCC catalyst is produced. At present, about 150,000 tons of waste FCC catalyst is produced in China every year, and it is still increasing year by year. The heavy metal oxides existing in the abandoned waste FCC catalyst can penetrate into the soil and be brought into the water by rain, polluting the environment and ultimately affecting human health. Therefore, it is necessary to scientifically and effectively treat the waste FCC catalyst without harm, avoid its harm to the environment and human health, and realize resource recycling.

[0003] At present, the harmless treatment of waste FCC catalyst at home and abroad mainly adopts pyrolysis method and leaching method, etc., in which the pyrolysis method is to pyrolyze the harmful substances in the waste FCC catalyst at high temperature. The leaching method is to use acid or alkaline leaching agent to convert the heavy metal oxides in the waste FCC catalyst into harmless components. Although the pyrolysis method and the leaching method can realize the harmless treatment of the waste FCC catalyst, the treatment cost is too high and the solid waste resources are not fully utilized. The methods of recycling and reusing waste FCC catalyst mainly include preparing molecular sieve, recycling precious metals and serving as building material, etc. Although preparing molecular sieve can maximize the recycling of waste FCC catalyst which may cause environmental pollution and be used to produce new catalyst, and recycling precious metals also has certain economic value, these methods need to consume a large amount of energy and materials, and the process is complex, so the production cost is high. Using waste FCC catalyst as building material may cause the residue of harmful substances and has low economic benefit. Therefore, when seeking the harmless treatment and reuse of waste FCC catalyst, safety, process complexity, high added value and other aspects should be considered comprehensively.

[0004] With the continuous development of wireless communication equipment and electronic technology, the problem of electromagnetic radiation pollution is becoming increasingly serious, and it has attracted people's attention to wave-absorbing materials. Wave-absorbing materials can be widely used in electromagnetic shielding, preventing electromagnetic radiation of high-frequency electronic equipment, constructing microwave darkroom and stealth technology, etc. At present, wave-absorbing materials are developing in the direction of high performance, not only need to have strong absorption capacity, but also need to have the characteristics of light weight, wide frequency, good stability, etc., and the preparation process also presents the trend of low cost and simplification.

[0005] In summary, if waste FCC catalyst can be used as raw material to prepare microwave absorbing composite materials, not only can avoid the adverse effects of waste FCC catalyst on the environment and human health, but also can realize high value-added recycling of waste FCC catalyst, which is in line with the concept of national sustainable development. SUMMARY

[0006] The purpose of the present application is to provide a method for utilizing waste petroleum catalytic cracking catalyst and a microwave absorbing composite material with high added value prepared by the method. The raw material cost is low, which achieves the purpose of harmless treatment of waste FCC catalyst, and the microwave absorbing composite material has excellent microwave absorbing performance.

[0007] To achieve the above purpose, the present application adopts the following technical scheme: a method for utilizing waste petroleum catalytic cracking catalyst, comprising the following steps:

[0008] Step 1: crushing the waste FCC catalyst to obtain waste FCC catalyst powder;

[0009] Step 2: soaking 6-16 parts by mass of carbon black in sufficient ethanol ， ultrasonic dispersion, adding 60-78 parts by mass of waste FCC catalyst powder, and stirring uniformly to obtain a mixed slurry;

[0010] Step 3: adding 16-23 parts by mass of phenolic resin to the mixed slurry, ball milling uniformly, and drying to obtain a precursor powder;

[0011] Step 4: placing the precursor powder in an inert atmosphere, calcining at a temperature of 1300-1400℃ for 1-2h, and obtaining a microwave absorbing composite material.

[0012] Further improvement of the method for utilizing waste petroleum catalytic cracking catalyst:

[0013] Preferably, the waste FCC catalyst is a waste catalyst generated in the process of petroleum catalytic cracking.

[0014] Preferably, the waste FCC catalyst is crushed and sieved through a 200 mesh standard sieve to obtain waste FCC catalyst powder.

[0015] Preferably, the particle size of the carbon black in step 2 is 30-50nm.

[0016] Preferably, the frequency of ultrasonic oscillation in step 2 is 30-60KHz, and the time is 30-60min.

[0017] Preferably, the rotation speed of ball milling in step 3 is 300-500rpm, and the time is 6-8h.

[0018] Preferably, the temperature in step 4 is raised to the calcination temperature by gradient heating, and the specific process is as follows: the temperature is raised from room temperature to 800-900 DEG C at a rate of 5-10 DEG C / min, and then the temperature is raised to 1300-1400 DEG C at a rate of 5-10 DEG C / min.

[0019] The second object of the present application is to provide a microwave absorbing composite material prepared by the utilization method of the waste oil catalytic cracking catalyst.

[0020] As a further improvement of the microwave absorbing composite material:

[0021] Preferably, the microwave absorbing composite material is applied in the field of electromagnetic wave shielding and electromagnetic wave absorption.

[0022] The present application has the following advantages compared with the prior art:

[0023] 1) The present application uses waste FCC catalyst as the matrix, and prepares the microwave absorbing composite material by adding carbon black and high-temperature sintering. Screening controls the particle size of the waste FCC catalyst within 75 microns, which can make the ball milling mixing of the waste FCC catalyst and the carbon black more uniform to obtain the optimal wave absorption performance. Meanwhile, the prepared microwave absorbing composite material can also be more uniformly dispersed in the matrix during use. By ball milling, a certain amount of carbon black particles are loaded on the surface of the waste FCC catalyst to regulate its complex permittivity to form good dielectric loss. The main components of the waste FCC catalyst are Al2O3 and SiO2, and after high-temperature sintering, the heavy metal oxides V2O5 and NiO in the waste FCC catalyst are converted into AlV2O4 and NiAl2O4 spinel phases, which achieves harmless treatment of the waste FCC catalyst. The introduced carbon black generates silicon carbide through carbothermic reduction at high temperature, and the mullite and silicon carbide in the composite material can provide good impedance matching, and also have good high-temperature resistance, chemical stability and mechanical properties. At the same time of solidifying the heavy metal oxides to completely solve the environmental pollution of the waste FCC catalyst, the useful resources are recovered, and the high-value utilization of the waste FCC catalyst is achieved.

[0024] 2) The present application reasonably designs the amount of carbon black loaded on the surface of the waste FCC catalyst powder, which avoids the situation that when the loading amount is small, the dielectric loss cannot provide sufficient electromagnetic wave loss, and when the loading amount is too large, the dielectric loss is too large to cause impedance mismatch and cannot make the electromagnetic wave enter, and also cannot effectively lose the electromagnetic wave. At the same time, the rich heterogeneous interfaces formed in the composite material can form a large number of interfacial polarizations, which is also beneficial to improving the microwave absorption performance of the composite material. The composite material has good impedance matching and dielectric loss, and exhibits excellent electromagnetic wave attenuation ability.

[0025] 3) The microwave absorbing composite material prepared by the present application has excellent microwave absorption performance, and the minimum reflection loss RLmin The minimum reflectivity reaches -55.91dB, and the widest effective absorption bandwidth reaches 5.8GHz. The low-cost and high-efficiency microwave absorption composite material can be widely applied in the construction of microwave darkroom, the prevention of high-frequency electromagnetic radiation in electronic equipment, and electromagnetic shielding in radio communication system, etc. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 is a SEM image of the waste FCC catalyst used in the present application;

[0027] Figure 2 is an XRD image of the microwave absorption composite material prepared in Example 1 of the present application;

[0028] Figure 3 is a SEM image of the microwave absorption composite material prepared in Example 1 of the present application;

[0029] Figure 4 is a reflection loss image of the microwave absorption composite material prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical scheme and advantages of the present application more clear, the present application is further described in detail below in combination with examples. All other examples obtained by those skilled in the art based on the examples in the present application without making creative efforts belong to the scope of protection of the present application.

[0031] Example 1

[0032] Step 1, the waste FCC catalyst was crushed and passed through a 200 mesh standard sieve to obtain waste FCC catalyst powder;

[0033] Step 2, 15 parts by weight of carbon black was immersed in 20ml of ethanol, and then placed in an ultrasonic instrument under a power of 60KHz for 30min. 62 parts by weight of waste FCC catalyst powder was added and stirred uniformly to obtain a mixed slurry;

[0034] Step 3, 23 parts by weight of phenolic resin was added to the mixed slurry, and ball-milled at a speed of 500rpm for 6 hours to mix uniformly, and then dried to obtain a precursor powder;

[0035] Step 4, the precursor powder was placed in a crucible, and the crucible was placed in a tube furnace for sintering under an inert atmosphere. The temperature was increased from room temperature to 800℃ at a rate of 5℃ / min, and then to 1400℃ at a rate of 10℃ / min. The sintering was carried out at this temperature for 120min to obtain a microwave absorption composite material.

[0036] The obtained microwave absorbing composite material is mixed with paraffin at a mass ratio of 4:6 after heating at 80°C, uniformly mixed, and formed by mold pressing. The microwave absorbing performance is measured by using an Agilent vector network analyzer, and the results are as follows: when the matching thickness d is 3.2 mm, the minimum reflection loss RL min is-55.91 dB, and the effective absorption bandwidth is 3.48 GHz; when the matching thickness is 2.0 mm, the minimum reflection loss RL min is-19.37 dB, and the effective absorption bandwidth can reach 4.84 GHz.

[0037] Example 2

[0038] Step 1: The waste FCC catalyst is crushed and sieved through a 200 mesh standard sieve to obtain waste FCC catalyst powder;

[0039] Step 2: 16 parts by weight of carbon black is immersed in 20 ml of ethanol, and then placed in an ultrasonic instrument under a power of 60 KHz for 30 min. 60 parts by weight of waste FCC catalyst powder is added and stirred uniformly to obtain a mixed slurry;

[0040] Step 3: 23 parts by weight of phenolic resin is added to the mixed slurry, and stirred for 6 hours at a speed of 500 rpm, and then dried to obtain a precursor powder;

[0041] Step 4: The precursor powder is placed in a crucible, and the crucible is placed in a tube furnace for sintering under an inert atmosphere. The temperature is increased from room temperature to 800°C at a rate of 5°C / min, and then increased to 1400°C at a rate of 10°C / min. The temperature is maintained at 1400°C for 120 min to obtain a microwave absorbing composite material.

[0042] The obtained microwave absorbing composite material is mixed with paraffin at a mass ratio of 4:6 after heating at 80°C, uniformly mixed, and formed by mold pressing. The microwave absorbing performance is measured by using an Agilent vector network analyzer, and the results are as follows: when the matching thickness d is 3.6 mm, the minimum reflection loss RL min is-43.05 dB, and the effective absorption bandwidth is 2.36 GHz; when the matching thickness is 1.9 mm, the minimum reflection loss RL min is-21.25 dB, and the effective absorption bandwidth can reach 4.64 GHz.

[0043] Example 3

[0044] Step 1: The waste FCC catalyst is crushed and sieved through a 200 mesh standard sieve to obtain waste FCC catalyst powder;

[0045] Step 2, 14 parts by weight of carbon black was immersed in 20 ml of ethanol, then placed in an ultrasonic instrument under the power of 60 KHz for 30 min, 63 parts by weight of waste FCC catalyst powder was added, and the mixture was stirred to obtain a mixed slurry;

[0046] Step 3, 23 parts by weight of phenolic resin was added to the mixed slurry, and the mixture was ball milled at a speed of 500 rpm for 6 hours, then dried to obtain a precursor powder;

[0047] Step 4, the precursor powder was placed in a crucible, and the crucible was placed in a tube furnace for sintering under an inert atmosphere; the temperature was increased from room temperature to 800℃ at a rate of 5℃ / min, and then to 1400℃ at a rate of 10℃ / min, and sintered at this temperature for 120 min to obtain a microwave absorbing composite material.

[0048] The obtained microwave absorbing composite material was mixed with paraffin at a mass ratio of 4:6 after heating at 80℃, and then uniformly mixed, and then molded by pressing through a mold, and tested by using an Agilent vector network analyzer, and the microwave absorbing performance was as follows: at a matching thickness d of 5.0 mm, the minimum reflection loss RL min was-11.64 dB, and the effective absorption bandwidth was 1.28 GHz.

[0049] Example 4

[0050] Step 1, the waste FCC catalyst was crushed and passed through a 200 mesh standard sieve to obtain a waste FCC catalyst powder;

[0051] Step 2, 7 parts by weight of carbon black was immersed in 20 ml of ethanol, then placed in an ultrasonic instrument under the power of 60 KHz for 30 min, 77 parts by weight of waste FCC catalyst powder was added, and the mixture was stirred to obtain a mixed slurry;

[0052] Step 3, 16 parts by weight of phenolic resin was added to the mixed slurry, and the mixture was ball milled at a speed of 300 rpm for 8 hours, then dried to obtain a precursor powder;

[0053] Step 4, the precursor powder was placed in a crucible, and the crucible was placed in a tube furnace for sintering under an inert atmosphere; the temperature was increased from room temperature to 800℃ at a rate of 5℃ / min, and then to 1300℃ at a rate of 10℃ / min, and sintered at this temperature for 120 min to obtain a microwave absorbing composite material.

[0054] The obtained microwave absorbing composite material was mixed with paraffin at a mass ratio of 4:6 after heating at 80℃, and then uniformly mixed, and then molded by pressing through a mold, and tested by using an Agilent vector network analyzer, and the microwave absorbing performance was as follows: at a matching thickness d of 3.1 mm, the minimum reflection loss RLmin with a value of -49.93dB, and an effective absorption bandwidth of 3.16GHz; at a matching thickness of 2.1mm, the minimum reflection loss RL min is -24.03dB, and the effective absorption bandwidth can reach 5.12GHz.

[0055] Example 5

[0056] Step 1, the waste FCC catalyst is crushed and passed through a 200 mesh standard sieve to obtain waste FCC catalyst powder;

[0057] Step 2, 8 parts by weight of carbon black is immersed in 20ml of ethanol, then placed in an ultrasonic instrument under the power of 60KHz for 30min, 76 parts by weight of waste FCC catalyst powder is added, and stirred uniformly to obtain a mixed slurry;

[0058] Step 3, 16 parts by weight of phenolic resin is added to the mixed slurry, and stirred uniformly for 8 hours at a speed of 300r / min, and then dried to obtain a precursor powder;

[0059] Step 4, the precursor powder is placed in a crucible, and the crucible is placed in a tube furnace for sintering under an inert atmosphere; the temperature is increased from room temperature to 800℃ at a rate of 5℃ / min, and then to 1300℃ at a rate of 10℃ / min, and sintered at this temperature for 120min to obtain a microwave absorbing composite material.

[0060] The obtained microwave absorbing composite material is mixed uniformly with paraffin at a mass ratio of 4:6 after heating at 80℃, and then molded by pressing through a mold, and tested by an Agilent vector network analyzer, and the wave absorption performance is as follows: at a matching thickness d of 1.6mm, the minimum reflection loss RL min with a value of -25.67dB, and an effective absorption bandwidth of 3.32GHz; at a matching thickness of 1.9mm, the minimum reflection loss RL min is -20.23dB, and the effective absorption bandwidth can reach 5.80GHz.

[0061] Example 6

[0062] Step 1, the waste FCC catalyst is crushed and passed through a 200 mesh standard sieve to obtain waste FCC catalyst powder;

[0063] Step 2, 6 parts by weight of carbon black is immersed in 20ml of ethanol, then placed in an ultrasonic instrument under the power of 60KHz for 30min, 78 parts by weight of waste FCC catalyst powder is added, and stirred uniformly to obtain a mixed slurry;

[0064] Step 3, 16 parts by weight of phenolic resin was added into the mixed slurry, and then the mixture was uniformly mixed by ball milling at a rotation speed of 300 rpm for 8 hours, and then dried to obtain a precursor powder;

[0065] Step 4, the precursor powder was placed in a crucible, and then the crucible was placed in a tube furnace for sintering under an inert atmosphere; the temperature was increased from room temperature to 800℃ at a rate of 5℃ / min, and then increased to 1300℃ at a rate of 10℃ / min, and sintered at this temperature for 120 min to obtain a microwave absorbing composite material.

[0066] The obtained microwave absorbing composite material was uniformly mixed with paraffin at a mass ratio of 4:6 after heating at 80℃, and then molded by a mold, and then tested by an Agilent vector network analyzer, and the wave absorption performance was as follows: the minimum reflection loss RL min was-14.49 dB, and the effective absorption bandwidth was 2.52 GHz.

[0067] Comparative Example 1

[0068] 100 parts by weight of waste FCC catalyst was placed in a crucible, and then the crucible was placed in a tube furnace for sintering under an inert atmosphere; the sintering temperature was 1300℃, and the sintering cycle was 120 min, to obtain a sintered product 1.

[0069] The sintered product 1 was uniformly mixed with paraffin at a mass ratio of 4:6 after heating at 80℃, and then molded by a mold, and then tested by an Agilent vector network analyzer, and the wave absorption performance was as follows: no effective wave band was found.

[0070] Comparative Example 2

[0071] 100 parts by weight of waste FCC catalyst was placed in a crucible, and then the crucible was placed in a tube furnace for sintering under an inert atmosphere; the sintering temperature was 1400℃, and the sintering cycle was 120 min, to obtain a sintered product 2.

[0072] The sintered product 2 was uniformly mixed with paraffin at a mass ratio of 4:6 after heating at 80℃, and then molded by a mold, and then tested by an Agilent vector network analyzer, and the wave absorption performance was as follows: no effective wave band was found.

[0073] Table 1 Comparison of wave absorption performance of products of Examples 1-6 and Comparative Examples 1-2

[0074] Sample RL min (dB) Greatest effective absorption bandwidth (GHz) Example 1 -55.91 4.84 Example 2 -21.25 4.64 Example 3 -11.64 1.28 Example 4 -49.93 5.12 Example 5 -25.67 5.80 Example 6 -14.49 2.52 Comparative Example 1 -5.58 0 Comparative Example 2 -6.35 0

[0075] As can be seen from the comparison of the microwave absorption performance of Examples 1-6 and Comparative Examples 1-2 in Table 1, the microwave absorbing composite material prepared by ball milling loaded carbon black and then carbothermally reducing it to form silicon carbide exhibits excellent microwave absorption performance. This is because the silicon carbide, mullite, and corundum ceramic phases formed after high-temperature sintering provide good impedance matching, while the carbon black ball-milled on its surface can form a conductive network to provide good dielectric loss. In addition, the abundant heterogeneous interfaces formed inside the material can generate a large number of interfacial polarizations, which can also effectively improve the microwave absorption performance of the composite material. In summary, a high-performance microwave absorbing composite material can be prepared by sintering waste FCC catalyst loaded with an appropriate amount of carbon black.

[0076] Figure 1 These are SEM images of the spent FCC catalysts used in the embodiments and comparative examples of this invention; Figure 2 This is the XRD pattern of the microwave absorbing composite material prepared in Example 1 of the present invention; Figure 3 Here is a SEM image of the microwave absorbing composite material prepared in Example 1 of this invention; Figure 4 The image shows the reflection loss of the microwave absorbing composite material prepared in Example 1 of this invention.

[0077] Combination Figure 1 , Figure 2 and Figure 3 The test results show that, through high-temperature sintering, the heavy metals V2O5 and NiO in the waste FCC catalyst are transformed into AlV2O4 and NiAl2O4 spinel, thus rendering the harmful heavy metal oxides harmless. Simultaneously, after high-temperature sintering, the waste FCC matrix is ​​transformed into silicon carbide, mullite, and corundum ceramic matrices, providing good impedance matching for the composite material.

[0078] Depend on Figure 4 The test results of the microwave absorbing composite material prepared in Example 1 show that the microwave absorbing composite material has excellent microwave absorption performance, and the minimum reflection loss RL is achieved when the matching thickness d is 3.2 mm. min Its value is -55.91 dB; similarly, the microwave absorbing composite material prepared in Example 2 was tested, and the minimum reflection loss RL was achieved when the matching thickness d was 3.6 mm. min Its value is -43.05dB; similarly, the microwave absorbing composite material prepared in Example 3 was tested, and the minimum reflection loss RL was achieved when the matching thickness d was 5mm. min Its value is -11.64 dB; similarly, the microwave absorbing composite material prepared in Example 4 was tested, and the minimum reflection loss RL was achieved when the matching thickness d was 3.1 mm. min Its value is -49.93dB; similarly, the microwave absorbing composite material prepared in Example 5 was tested, and the minimum reflection loss RL was achieved when the matching thickness d was 1.6mm. minwhose value is -25.67 dB; the microwave absorbing composite material prepared in Example 6 was also tested, and the minimum reflection loss RL was reached when the matching thickness d was 5 mm min whose value is -14.49 dB; the test results prove that the microwave absorbing composite materials prepared in Examples 1-6 can all achieve more than 90% absorption of the electromagnetic waves passing therethrough.

[0079] Those skilled in the art should understand that the above description is only several specific embodiments of the present application, not all embodiments. It should be noted that many modifications and improvements can also be made by those of ordinary skill in the art, and all modifications or improvements that do not exceed the scope of the claims should be considered as the protection scope of the present application.

Claims

1. A method for utilizing waste petroleum catalytic cracking catalyst, characterized in that, Includes the following steps: Step 1: Crush the waste FCC catalyst to obtain waste FCC catalyst powder; Step 2: Impregnate 6-16 parts by weight of carbon black in sufficient ethanol. ， After ultrasonic vibration and uniform dispersion, add 60-78 parts by weight of waste FCC catalyst powder and stir evenly to obtain a mixed slurry; Step 3: Add 16-23 parts by weight of phenolic resin to the mixed slurry, ball mill and mix well, then dry to obtain precursor powder; Step 4: Place the precursor powder in an inert atmosphere and calcine it at 1300-1400℃ for 1-2 hours to obtain the microwave absorbing composite material.

2. The method for utilizing waste petroleum catalytic cracking catalyst according to claim 1, characterized in that, The waste FCC catalyst is a waste catalyst generated during the petroleum catalytic cracking process.

3. The method for utilizing waste petroleum catalytic cracking catalyst according to claim 1 or 2, characterized in that, The waste FCC catalyst was pulverized and passed through a 200-mesh standard sieve to obtain waste FCC catalyst powder.

4. The method for utilizing waste petroleum catalytic cracking catalyst according to claim 1, characterized in that, The carbon black in step 2 has a particle size of 30-50 nm.

5. The method for utilizing waste petroleum catalytic cracking catalyst according to claim 1, characterized in that, In step 2, the frequency of ultrasonic oscillation is 30-60 kHz, and the duration is 30-60 min.

6. The method for utilizing waste petroleum catalytic cracking catalyst according to claim 1, characterized in that, In step 3, the ball mill rotates at 300-500 rpm for 6-8 hours.

7. The method for utilizing waste petroleum catalytic cracking catalyst according to claim 1, characterized in that, In step 4, the temperature is raised to the calcination temperature by gradient heating. Specifically, the temperature is raised from room temperature to 800-900℃ at a heating rate of 5-10℃ / min, and then raised to 1300-1400℃ at a heating rate of 5-10℃ / min.

8. A microwave-absorbing composite material prepared by utilizing the waste petroleum catalytic cracking catalyst as described in any one of claims 1-7.

9. The microwave absorbing composite material according to claim 8, characterized in that, This microwave absorbing composite material is used in the fields of electromagnetic wave shielding and electromagnetic wave absorption.

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