CN116239372A - Preparation method of terahertz material for reducing emission of nitrogen oxides and volatile organic compounds - Google Patents

Preparation method of terahertz material for reducing emission of nitrogen oxides and volatile organic compounds Download PDF

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CN116239372A
CN116239372A CN202310276517.2A CN202310276517A CN116239372A CN 116239372 A CN116239372 A CN 116239372A CN 202310276517 A CN202310276517 A CN 202310276517A CN 116239372 A CN116239372 A CN 116239372A
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terahertz
nitrogen oxides
organic compounds
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CN116239372B (en
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王宗爽
顾闫悦
徐舒
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Chinese Research Academy of Environmental Sciences
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Abstract

The invention discloses a preparation method of a terahertz material for reducing emission of nitrogen oxides and volatile organic compounds, which comprises the following steps: mixing the raw materials: uniformly mixing silicon dioxide, ferric oxide and calcium tungstate to obtain mixed raw material powder; and (3) melting and crystallizing: melting the mixed raw material powder, cooling and crystallizing, and re-crushing the mixed crystals obtained by crystallizing to obtain mixed crystal powder; and (5) press forming: adding modified graphene oxide and/or nano silicon-based oxide into the mixed crystal powder, and uniformly mixing to obtain terahertz powder; pressing and forming the terahertz powder to obtain a terahertz material block; and (3) heat treatment: placing the terahertz material block into a calciner for sintering, cooling and crushing after the sintering is finished to obtain a terahertz material; and (3) irradiation strengthening treatment: and placing the terahertz material in a terahertz irradiation line environment for irradiation strengthening treatment. When the terahertz material is used for reducing emission of nitrogen oxides and volatile organic compounds by a combustion source, the emission reduction efficiency and stability are good.

Description

Preparation method of terahertz material for reducing emission of nitrogen oxides and volatile organic compounds
Technical Field
The invention relates to the technical field of terahertz materials. In particular to a preparation method of a terahertz material for reducing emission of nitrogen oxides and volatile organic compounds.
Background
Nitrogen oxides and volatile organics are precursors to ozone and secondary PM2.5, and improvements in ambient air quality must enhance emissions control for nitrogen oxides and volatile organics. At present, the Selective Catalytic Reduction (SCR) and the selective non-catalytic reduction (SNCR) are mainly adopted in China to carry out terminal control on nitrogen oxides generated after combustion of a combustion source, but the emission of volatile organic compounds of the combustion source is hardly controlled. The tail end control mode can reduce emission of nitrogen oxides and volatile organic compounds, but increases energy consumption and ammonia escape, so that carbon emission is increased, and secondary pollution is caused by ammonia escape.
In recent exploration, materials capable of emitting terahertz spectrum show a certain promotion effect on emission reduction of nitrogen oxides and volatile organic compounds of combustion sources. For example, patent CN111875819a prepares a terahertz master batch for reducing emission and saving oil of a gasoline vehicle, which can emit terahertz waves to activate oil fuel, air, cooling liquid and the like, reduce HC of the vehicle by 90% on average, NOx by 70% on average, save fuel by 10% on average, improve power by 8% and reduce carbon deposition, prolong service life of a three-way catalyst, and reduce contribution of tail gas to PM2.5 by 90%.
However, the inventor of the application repeatedly tests the terahertz material applied to other mobile source fuels such as diesel vehicles and the like, and finds that the efficiency of promoting the emission reduction of nitrogen oxides and volatile organic compounds is unstable, and in some tests, more harmful substances are discharged from tail gas, so that the harmful substances have great deviation. Therefore, it is necessary to design a preparation method of the terahertz material capable of reducing the emission of the nitrogen oxides and the volatile organic compounds of the combustion source, and the prepared terahertz material has relatively stable emission promotion and reduction effects of the nitrogen oxides and the volatile organic compounds of the combustion source.
Disclosure of Invention
Therefore, the technical problem to be solved by the invention is to provide a preparation method of the terahertz material capable of reducing emission of nitrogen oxides and volatile organic compounds of a combustion source, so as to solve the problem that the emission reduction efficiency and stability of the existing terahertz material are poor when the existing terahertz material is used for reducing the emission of the nitrogen oxides and the volatile organic compounds of the combustion source.
In order to solve the technical problems, the invention provides the following technical scheme:
the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds comprises the following steps:
step (1), mixing the raw materials: uniformly mixing silicon dioxide, ferric oxide and calcium tungstate to obtain mixed raw material powder;
step (2), melting and crystallizing: melting the mixed raw material powder, cooling and crystallizing, and re-crushing the mixed crystals obtained by crystallizing to obtain mixed crystal powder;
step (3), compression molding: adding modified graphene oxide and/or nano silicon-based oxide into the mixed crystal powder, and uniformly mixing to obtain terahertz powder; pressing and forming the terahertz powder to obtain a terahertz material block;
step (4), heat treatment: placing the terahertz material block into a calciner for sintering, cooling and crushing after the sintering is finished to obtain a terahertz material;
step (5), irradiation strengthening treatment: and placing the terahertz material in a terahertz irradiation line environment for irradiation strengthening treatment.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (1), the mass ratio of silicon dioxide, ferric oxide and calcium tungstate is as follows: (3-5) (1-3) (1-2); the silicon dioxide, ferric oxide and calcium tungstate are all sieved by a 200-mesh sieve.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (2), the melting temperature is 1600-1800 ℃ and the melting time is 1-1.5 h; and (3) crushing the mixed crystals, and sieving the crushed mixed crystals with a 300-mesh sieve to obtain mixed crystal powder.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (3), the pressure of compression molding is 3-5 MPa, and the pressure maintaining time is 10-20 min; the press forming temperature is room temperature;
when the modified graphene oxide is added into the mixed crystal powder, the mass ratio of the mixed crystal powder to the modified graphene oxide is 5-8:1;
when the nano silicon-based oxide is added into the mixed crystal powder, the mass ratio of the mixed crystal powder to the nano silicon-based oxide is 3-5:1;
when the modified graphene oxide and the nano silicon-based oxide are added into the mixed crystal powder, the ratio of the mass of the mixed crystal powder to the sum of the mass of the modified graphene oxide and the mass of the nano silicon-based oxide is as follows: 2-5:1, and the mass ratio of the modified graphene oxide to the nano silicon-based oxide is 1:2-3.
The preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds comprises the following steps of:
step (A-1), ultrasonically dispersing graphene oxide in dimethyl sulfoxide to obtain graphene oxide dispersion liquid;
step (A-2), adding silica gel and N, N' -diisopropylcarbodiimide into graphene oxide dispersion liquid, and placing in a water bath for heating reaction;
and (A-3) cleaning a product obtained by the reaction with water and methanol in sequence, and drying to obtain the modified graphene oxide.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (A-1), the mass fraction of graphene oxide in the graphene oxide dispersion liquid is 15-20wt%;
in the step (A-2), the mass ratio of graphene oxide, silica gel and N, N' -diisopropylcarbodiimide is as follows: 1: (15-20): (2-4); the temperature of the heating reaction is 30-40 ℃, and the time of the heating reaction is 30-60 min.
The preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds comprises the following steps of:
step (B-1), placing magnesium sulfate and tetraethoxysilane into water to be uniformly dispersed to obtain mixed dispersion liquid; adding inorganic acid into the mixed dispersion liquid for reaction, adjusting the pH value to be neutral after the reaction is completed, and standing to obtain a mixed system A;
adding acetone into the mixed system A for stirring, then adding vinyl triethoxysilane, continuing stirring, and obtaining a mixed system B after stirring is finished;
and (B-3) drying the mixed system B to obtain the nano silicon-based oxide.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (B-1), the mass ratio of magnesium sulfate to tetraethyl orthosilicate to water is 1: (1-1.5): (2-3); the addition amount of the inorganic acid is such that the pH of the mixed dispersion is from 4 to 5; the reaction time is 4-6 h, and the standing time is 16-24 h;
the ratio of the volume of acetone in step (B-2) to the volume of water in step (B-1) was 1: 8-10, wherein the volume ratio of the vinyl triethoxysilane to the acetone is 1.5-2:1; the stirring time after adding acetone is 1 to 1.5 hours, and the stirring time after adding vinyl triethoxysilane is 2 to 3 hours;
in the step (B-3), the drying temperature is 60-70 ℃ and the drying time is 12-24 h.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (4), the sintering temperature is 1100-1300 ℃ and the sintering time is 1-2 h; the grain diameter of the terahertz material is 10-50 mu m.
In the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds, in the step (5), the irradiation strengthening treatment conditions are as follows: first at 2.3X10 11 Radiation treatment for 1-3 h under frequency band, then at 5.5X10 11 The radiation treatment is carried out for 1 to 3 hours under the frequency band, and then the radiation treatment is carried out at 2.3X10 12 Radiation treatment for 1-3 h under frequency band, and finally at 5.5X10 12 And carrying out radiation treatment for 1-3 h under the frequency band.
The technical scheme of the invention has the following beneficial technical effects:
1. according to the invention, three terahertz materials with relatively similar melting points are firstly melted and mixed, and then modified graphene oxide and/or nano silicon-based oxide are added, so that the terahertz material with high emissivity can be prepared, and the terahertz material has good emission reduction efficiency and stability when being used for reducing emission of nitrogen oxides and volatile organic compounds by a combustion source.
2. According to the preparation method, graphene oxide is used after being modified, so that the emissivity of the prepared terahertz material and the stability of emission reduction energy efficiency of the terahertz material can be effectively improved, and the preparation method is probably because: the graphene oxide bonded by the silica gel can better cooperate with terahertz materials such as silicon dioxide, ferric oxide, calcium tungstate and the like to mutually excite the radiation performance of the terahertz materials, and finally the terahertz materials with high emissivity are obtained.
3. Compared with common silicon dioxide, the nano silicon-based oxide has a special lattice structure, so that the terahertz material has higher emissivity; in addition, the nano silicon-based oxide prepared by the preparation method can keep higher emissivity of the terahertz material under different use conditions in the presence of the calcium tungstate, and the synergistic effect of the nano silicon-based oxide and the modified graphite oxide is more obvious when the modified graphite oxide is added into the terahertz material.
Detailed Description
Example 1
In this embodiment, the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds includes the following steps:
step (1), mixing the raw materials: uniformly mixing silicon dioxide, ferric oxide and calcium tungstate to obtain mixed raw material powder; the mass ratio of the silicon dioxide, the ferric oxide and the calcium tungstate is 3:2:1; the silicon dioxide, ferric oxide and calcium tungstate are all sieved by a 200-mesh sieve.
Step (2), melting and crystallizing: melting the mixed raw material powder at 1750 ℃ for 1h, cooling for crystallization, re-crushing the mixed crystals obtained by crystallization, and sieving with a 300-mesh sieve to obtain mixed crystal powder;
step (3), compression molding: adding modified graphene oxide into the mixed crystal powder, wherein the mass ratio of the mixed crystal powder to the modified graphene oxide is 5:1, and uniformly mixing to obtain terahertz powder; maintaining the pressure of the terahertz powder for 10 min at room temperature and 5MPa, and performing compression molding to obtain a terahertz material block;
step (4), heat treatment: placing the terahertz material block into a calciner for sintering, wherein the sintering temperature is 1200 ℃, and the sintering time is 2 hours; cooling and crushing after sintering to obtain a terahertz material, wherein the particle size of the terahertz material is 10-50 mu m;
step (5), irradiation strengthening treatment: placing the terahertz material in a terahertz irradiation line environment for irradiation strengthening treatment; the irradiation strengthening treatment conditions are as follows: first at 2.3X10 11 Radiation treatment for 1-3 h under frequency band, then at 5.5X10 11 The radiation treatment is carried out for 1 to 3 hours under the frequency band, and then the radiation treatment is carried out at 2.3X10 12 Radiation treatment for 1-3 h under frequency band, and finally at 5.5X10 12 And carrying out radiation treatment for 1-3 h under the frequency band.
The preparation method of the modified graphene oxide added in the step (3) of the embodiment comprises the following steps:
step (A-1), ultrasonically dispersing graphene oxide in dimethyl sulfoxide to obtain graphene oxide dispersion liquid; the mass fraction of graphene oxide in the graphene oxide dispersion liquid is 20wt%;
step (A-2), adding silica gel and N, N' -diisopropylcarbodiimide into graphene oxide dispersion liquid, and placing in a water bath for heating reaction; the mass ratio of graphene oxide, silica gel and N, N' -diisopropylcarbodiimide is as follows: 1:15:2, heating reaction temperature is 38 ℃, and heating reaction time is 50 min;
and (A-3) cleaning a product obtained by the reaction with water and methanol in sequence, and drying to obtain the modified graphene oxide.
The infrared emissivity of the terahertz material prepared in the embodiment reaches 91.3%, and the terahertz material prepared in the embodiment is added into cooling liquid of a gasoline vehicle and a diesel vehicle for repeated tests respectively, so that the results show that the amounts of nitrogen oxides and volatile organic compounds discharged by combustion of the gasoline vehicle and the diesel vehicle after the terahertz material is added are obviously reduced; the terahertz material promotes the stable emission reduction efficiency of nitrogen oxides and volatile organic compounds.
Example 2
In this embodiment, the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds includes the following steps:
step (1), mixing the raw materials: uniformly mixing silicon dioxide, ferric oxide and calcium tungstate to obtain mixed raw material powder; the mass ratio of the silicon dioxide, the ferric oxide and the calcium tungstate is 5:3:2; the silicon dioxide, ferric oxide and calcium tungstate are all sieved by a 200-mesh sieve.
Step (2), melting and crystallizing: melting the mixed raw material powder at 1600 ℃ for 1.5 hours, cooling and crystallizing, re-crushing the mixed crystals obtained by crystallization, and sieving with a 300-mesh sieve to obtain mixed crystal powder;
step (3), compression molding: adding nano silicon-based oxide into the mixed crystal powder, wherein the mass ratio of the mixed crystal powder to the nano silicon-based oxide is 5:1, and uniformly mixing to obtain terahertz powder; maintaining the pressure of the terahertz powder at room temperature and 3MPa for 20min, and performing compression molding to obtain a terahertz material block;
step (4), heat treatment: placing the terahertz material block into a calciner for sintering, wherein the sintering temperature is 1300 ℃, and the sintering time is 1h; cooling and crushing after sintering to obtain a terahertz material, wherein the particle size of the terahertz material is 10-50 mu m;
step (5), irradiation strengthening treatment: placing the terahertz material in a terahertz irradiation line environment for irradiation strengthening treatment; the irradiation strengthening treatment conditions are as follows: first at 2.3X10 11 Radiation treatment for 1-3 h under frequency band, then at 5.5X10 11 The radiation treatment is carried out for 1 to 3 hours under the frequency band, and then the radiation treatment is carried out at 2.3X10 12 Radiation treatment for 1-3 h under frequency band, and finally at 5.5X10 12 And carrying out radiation treatment for 1-3 h under the frequency band.
The preparation method of the nano silicon-based oxide added in the step (3) of the embodiment comprises the following steps:
step (B-1), placing magnesium sulfate and tetraethoxysilane into water to be uniformly dispersed to obtain mixed dispersion liquid; adding inorganic acid into the mixed dispersion liquid for reaction, adjusting the pH value to be neutral after the reaction is completed, and standing to obtain a mixed system A; the mass ratio of magnesium sulfate, ethyl orthosilicate and water is 1:1.5:3, a step of; the amount of the inorganic acid added is such that the pH of the mixed dispersion is 4; the reaction time is 5 hours, and the standing time is 20 hours;
step (B-2), adding acetone into the mixed system A, stirring for 1.5 hours, then adding vinyl triethoxysilane, continuously stirring for 3 hours, and obtaining a mixed system B after stirring is finished; the ratio of the volume of acetone to the volume of water in step (B-1) is 1:10, the volume ratio of vinyltriethoxysilane to acetone is 1.5:1;
and (B-3) drying the mixed system B at 70 ℃ for 24 hours to obtain the nano silicon-based oxide.
The infrared emissivity of the terahertz material prepared in the embodiment reaches 92.5%, and repeated tests are carried out by adding the terahertz material prepared in the embodiment into cooling liquid of a gasoline vehicle and a diesel vehicle respectively, so that the amounts of nitrogen oxides and volatile organic compounds discharged by combustion of the gasoline vehicle and the diesel vehicle after the terahertz material is added are obviously reduced; terahertz materials promote stable emission reduction of nitrogen oxides and volatile organic compounds, but the stability of the performance is slightly better than that of example 1.
Example 3
In this embodiment, the preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds includes the following steps:
step (1), mixing the raw materials: uniformly mixing silicon dioxide, ferric oxide and calcium tungstate to obtain mixed raw material powder; the mass ratio of the silicon dioxide, the ferric oxide and the calcium tungstate is 4:1:1; the silicon dioxide, ferric oxide and calcium tungstate are all sieved by a 200-mesh sieve.
Step (2), melting and crystallizing: melting the mixed raw material powder at 1800 ℃ for 1h, cooling for crystallization, re-crushing the mixed crystals obtained by crystallization, and sieving with a 300-mesh sieve to obtain mixed crystal powder;
step (3), compression molding: adding modified graphene oxide and nano silicon-based oxide into the mixed crystal powder, wherein the mass ratio of the mixed crystal powder to the modified graphene oxide to the nano silicon-based oxide is 5:1, and the mass ratio of the modified graphene oxide to the nano silicon-based oxide is 1:2; uniformly mixing to obtain terahertz powder; maintaining the pressure of the terahertz powder at room temperature and 4MPa for 15 min, and performing compression molding to obtain a terahertz material block;
step (4), heat treatment: placing the terahertz material block into a calciner for sintering, wherein the sintering temperature is 1100 ℃, and the sintering time is 2 hours; cooling and crushing after sintering to obtain a terahertz material, wherein the particle size of the terahertz material is 10-50 mu m;
step (5), irradiation strengthening treatment: placing the terahertz material in a terahertz irradiation line environment for irradiation strengthening treatment; the irradiation strengthening treatment conditions are as follows: first at 2.3X10 11 Radiation treatment for 1-3 h under frequency band, then at 5.5X10 11 The radiation treatment is carried out for 1 to 3 hours under the frequency band, and then the radiation treatment is carried out at 2.3X10 12 Radiation treatment for 1-3 h under frequency band, and finally at 5.5X10 12 And carrying out radiation treatment for 1-3 h under the frequency band.
The preparation method of the modified graphene oxide added in the step (3) of this embodiment is the same as that of embodiment 1, and the preparation method of the added nano silicon-based oxide is the same as that of embodiment 2.
The infrared emissivity of the terahertz material prepared in the embodiment reaches 95.8%, and repeated tests are carried out by adding the terahertz material prepared in the embodiment into cooling liquid of a gasoline vehicle and a diesel vehicle respectively, so that the amounts of nitrogen oxides and volatile organic compounds discharged by combustion of the gasoline vehicle and the diesel vehicle after the terahertz material is added are obviously reduced; terahertz materials promote stable emission reduction of nitrogen oxides and volatile organic compounds, but the stability of the performance is better than that of example 2.
Comparative example 1
This comparative example differs from example 1 only in that: in step (3), the modified graphene oxide in example 1 was replaced with commercially available graphene oxide.
The infrared emissivity of the terahertz material prepared in the comparative example reaches 85.6%, the terahertz material prepared in the comparative example is added into cooling liquid of a gasoline vehicle and a diesel vehicle to be subjected to repeated tests respectively, and the results show that the amounts of nitrogen oxides and volatile organic compounds discharged by combustion of the gasoline vehicle and the diesel vehicle after the terahertz material is added are reduced, but the reduction amplitude deviation is larger in different tests; the stability of the emission reduction performance was significantly poorer than that of example 1.
Comparative example 2
This comparative example differs from example 2 only in that: in step (3), commercially available nanosilicon dioxide was added in place of the nanosilicon-based oxide in example 2.
The infrared emissivity of the terahertz material prepared in the comparative example reaches 81.9%, the terahertz material prepared in the comparative example is added into cooling liquid of a gasoline vehicle and a diesel vehicle to be subjected to repeated tests respectively, and the results show that the amounts of nitrogen oxides and volatile organic compounds discharged by combustion of the gasoline vehicle and the diesel vehicle after the terahertz material is added are reduced, but the reduction amplitude deviation is larger in different tests; the stability of the emission reduction performance was significantly poorer than that of example 2.
Comparative example 3
This comparative example differs from example 3 only in that: mixing raw materials in the step (1): uniformly mixing silicon dioxide and ferric oxide to obtain mixed raw material powder; the mass ratio of the silicon dioxide to the ferric oxide is 4:2; both silica and ferric oxide were sieved through a 200 mesh screen.
The infrared emissivity of the terahertz material prepared in the comparative example reaches 89.7%, the terahertz material prepared in the comparative example is added into cooling liquid of a gasoline vehicle and a diesel vehicle to carry out repeated tests respectively, and the results show that the amounts of nitrogen oxides and volatile organic compounds discharged by combustion of the gasoline vehicle and the diesel vehicle after the terahertz material is added are reduced, but the reduction amplitude deviation is larger in different tests; the stability of the emission reduction performance was significantly poorer than that of example 1.
It is apparent that the above examples are given by way of illustration only and are not limiting of the embodiments. Other variations or modifications of the above teachings will be apparent to those of ordinary skill in the art. It is not necessary here nor is it exhaustive of all embodiments. While the obvious variations or modifications which are extended therefrom remain within the scope of the claims of this patent application.

Claims (10)

1. The preparation method of the terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds is characterized by comprising the following steps of:
step (1), mixing the raw materials: uniformly mixing silicon dioxide, ferric oxide and calcium tungstate to obtain mixed raw material powder;
step (2), melting and crystallizing: melting the mixed raw material powder, cooling and crystallizing, and re-crushing the mixed crystals obtained by crystallizing to obtain mixed crystal powder;
step (3), compression molding: adding modified graphene oxide and/or nano silicon-based oxide into the mixed crystal powder, and uniformly mixing to obtain terahertz powder; pressing and forming the terahertz powder to obtain a terahertz material block;
step (4), heat treatment: placing the terahertz material block into a calciner for sintering, cooling and crushing after the sintering is finished to obtain a terahertz material;
step (5), irradiation strengthening treatment: and placing the terahertz material in a terahertz irradiation line environment for irradiation strengthening treatment.
2. The method for producing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 1, wherein in step (1), the mass ratio of silica, ferric oxide, and calcium tungstate is: (3-5) (1-3) (1-2); the silicon dioxide, ferric oxide and calcium tungstate are all sieved by a 200-mesh sieve.
3. The method for producing terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 1, characterized in that in step (2), the melting temperature is 1600 to 1800 ℃ and the melting time is 1 to 1.5h; and (3) crushing the mixed crystals, and sieving the crushed mixed crystals with a 300-mesh sieve to obtain mixed crystal powder.
4. The method for producing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 1, wherein in step (3), the pressure of compression molding is 3 to 5MPa, and the dwell time is 10 to 20min; the press forming temperature is room temperature;
when the modified graphene oxide is added into the mixed crystal powder, the mass ratio of the mixed crystal powder to the modified graphene oxide is 5-8:1;
when the nano silicon-based oxide is added into the mixed crystal powder, the mass ratio of the mixed crystal powder to the nano silicon-based oxide is 3-5:1;
when the modified graphene oxide and the nano silicon-based oxide are added into the mixed crystal powder, the ratio of the mass of the mixed crystal powder to the sum of the mass of the modified graphene oxide and the mass of the nano silicon-based oxide is as follows: 2-5:1, and the mass ratio of the modified graphene oxide to the nano silicon-based oxide is 1:2-3.
5. The method for preparing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 1, wherein the preparation method of the modified graphene oxide in step (3) is as follows:
step (A-1), ultrasonically dispersing graphene oxide in dimethyl sulfoxide to obtain graphene oxide dispersion liquid;
step (A-2), adding silica gel and N, N' -diisopropylcarbodiimide into graphene oxide dispersion liquid, and placing in a water bath for heating reaction;
and (A-3) cleaning a product obtained by the reaction with water and methanol in sequence, and drying to obtain the modified graphene oxide.
6. The method for producing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 5, characterized in that in step (a-1), the mass fraction of graphene oxide in the graphene oxide dispersion is 15 to 20wt%;
in the step (A-2), the mass ratio of graphene oxide, silica gel and N, N' -diisopropylcarbodiimide is as follows: 1: (15-20): (2-4); the temperature of the heating reaction is 30-40 ℃, and the time of the heating reaction is 30-60 min.
7. The method for preparing terahertz material for reducing emissions of nitrogen oxides and volatile organic compounds according to claim 1, wherein the preparation method of nano silicon-based oxide in step (3) is as follows:
step (B-1), placing magnesium sulfate and tetraethoxysilane into water to be uniformly dispersed to obtain mixed dispersion liquid; adding inorganic acid into the mixed dispersion liquid for reaction, adjusting the pH value to be neutral after the reaction is completed, and standing to obtain a mixed system A;
adding acetone into the mixed system A for stirring, then adding vinyl triethoxysilane, continuing stirring, and obtaining a mixed system B after stirring is finished;
and (B-3) drying the mixed system B to obtain the nano silicon-based oxide.
8. The method for producing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds as claimed in claim 7, wherein in step (B-1), the mass ratio of magnesium sulfate, tetraethyl orthosilicate and water is 1: (1-1.5): (2-3); the addition amount of the inorganic acid is such that the pH of the mixed dispersion is from 4 to 5; the reaction time is 4-6 h, and the standing time is 16-24 h;
the ratio of the volume of acetone in step (B-2) to the volume of water in step (B-1) was 1: 8-10, wherein the volume ratio of the vinyl triethoxysilane to the acetone is 1.5-2:1; the stirring time after adding acetone is 1 to 1.5 hours, and the stirring time after adding vinyl triethoxysilane is 2 to 3 hours;
in the step (B-3), the drying temperature is 60-70 ℃ and the drying time is 12-24 h.
9. The method for preparing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 1, wherein in step (4), the sintering temperature is 1100-1300 ℃ and the sintering time is 1-2 h; the grain diameter of the terahertz material is 10-50 mu m.
10. The method for producing a terahertz material for reducing the emission of nitrogen oxides and volatile organic compounds according to claim 1, wherein in step (5), the irradiation strengthening treatment conditions are: first at 2.3X10 11 Radiation treatment for 1-3 h under frequency band, then at 5.5X10 11 The radiation treatment is carried out for 1 to 3 hours under the frequency band, and then the radiation treatment is carried out at 2.3X10 12 Radiation position under frequency bandThe treatment is carried out for 1 to 3 hours, and finally, the treatment is carried out at 5.5X10 12 And carrying out radiation treatment for 1-3 h under the frequency band.
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