CN108355665A - Energy simultaneous SO_2 and NO removal has spinel structure catalyst and its preparation method and application - Google Patents

Abstract

The invention discloses a catalyst capable of simultaneous desulfurization and denitrification with a spinel structure and its preparation method and application, comprising two or three active components of CoO, Fe ₂ O ₃ and Al ₂ O ₃ , and an auxiliary agent of One or both of CeO ₂ and Y ₂ O ₃ , the carrier is activated carbon; the active components of the catalyst form a spinel structure on the surface of the carrier. For simultaneous desulfurization and denitrification: CO is used as a reducing agent, and NO is reduced to N ₂ into the atmosphere by gas-solid catalytic reduction method, and SO ₂ is reduced to S simple substance for recycling. Activated carbon supports transition metal oxides and rare earth metals as additives, and the raw materials have wide sources, easy access, and low cost; activated carbon has the advantages of large specific surface area, good adsorption capacity, and rich oxygen-containing functional groups; the specific surface area of the catalyst is measured. 800-1500m ² /g.

Description

Catalyst with spinel structure capable of simultaneous desulfurization and denitrification, preparation method and application thereof

technical field

The invention relates to a desulfurization and denitrification catalyst, in particular to a catalyst with a spinel structure capable of simultaneous desulfurization and denitrification, a preparation method and application thereof.

Background technique

At present, energy loss mainly depends on the combustion of coal, so that SO ₂ and NO produced by coal combustion become the most important pollutants in air pollution, and their harm seriously affects _the ecological environment and human health. It must be done.

Compared with the combination of traditional SCR denitrification technology and FGD desulfurization technology to achieve the purpose of desulfurization and denitrification, desulfurization and denitrification have the advantages of saving floor space, reducing investment and operating costs, and have attracted widespread attention.

The existing simultaneous desulfurization and denitrification catalysts mainly include V ₂ O ₅ /AC, CuO/Al ₂ O ₃ , rare earth metal oxides and the like. These catalysts are medium-temperature or high-temperature catalysts. Generally, the effective catalytic temperature is above 300° C., and the catalytic activity decreases significantly when the temperature decreases.

The V ₂ O ₅ /AC catalyst disclosed in the patent No. CN 1475305A uses NH ₃ as the reducing agent gas. Although it can desulfurize and denitrify at a lower temperature, it is desulfurized by steps, first desulfurization and then SCR method Denitrification, and the denitrification rate is only 10-50%. The desulfurization and denitrification process will produce by-products that block the pores of the catalyst. After 2 hours of reaction, the activity of the catalyst will decrease, requiring regeneration, and the regeneration process is complicated.

Patent No. CN102962064A discloses Al ₂ O ₃ loaded CuO and Fe ₂ O ₃ catalysts, the catalytic temperature must be 350-800°C to achieve a good catalytic effect, and the temperature of the flue gas outlet is between 120-200°C, so Catalysts that consume too much energy and use Al ₂ O ₃ as a carrier have high bed resistance due to their particle shape, making it difficult to overcome dust blockage.

Patent No. CN201210463016.7 discloses activated carbon-supported rare earth metal oxide catalyst, using CO as the reducing agent, Pr ₆ O ₁₁ /AC has the best effect at 400°C, the conversion rate of SO ₂ reaches 99.3%, and the conversion rate of NO reaches 97.7% , still belongs to the range of medium and high temperature catalysts and the conversion rate still has room for improvement.

Activated carbon has the advantages of large specific surface area, good adsorption capacity, and rich oxygen-containing and nitrogen-containing functional groups. There are already patents on different methods of preparing activated carbon, but currently no transition metals are used as active components, and rare earth metals are used as additives. Activated carbon, and form a specific structure such as spinel, used in the patent report of simultaneous desulfurization and denitrification catalyst in flue gas.

Contents of the invention

The object of the present invention is to provide a catalyst with spinel structure capable of simultaneous desulfurization and denitrification, as well as its preparation method and application.

The purpose of the present invention is achieved through the following technical solutions:

The catalyst with spinel structure capable of simultaneous desulfurization and denitrification of the present invention includes: active components are two or three of CoO, Fe ₂ O ₃ and Al ₂ O ₃ , and additives are CeO ₂ and Y ₂ O ₃ One or two of them, the carrier is activated carbon;

The active components of the catalyst form a spinel structure on the surface of the carrier.

The preparation method of the above-mentioned spinel structure catalyst capable of simultaneous desulfurization and denitration of the present invention comprises the steps of:

First of all, the catalyst activated carbon carrier should be pretreated: prepare a HNO ₃ solution with a concentration of 5-15%, impregnate overnight at room temperature according to a certain mass ratio of HNO ₃ and AC, wash until neutral, dry and cool for later use;

Then, add active component and auxiliary agent, make catalyst sample;

Afterwards, the catalyst sample was pre-sulfided: the sulfidation atmosphere was SO ₂ +CO, the sulfidation temperature was 400-600° C., and the sulfidation time was 1 h.

The application of the above-mentioned spinel structure catalyst capable of simultaneous desulfurization and denitrification of the present invention is used for simultaneous desulfurization and denitrification _: CO is used as a reducing agent, and NO is reduced to N by a gas-solid phase catalytic reduction method and discharged into the atmosphere, and _{SO is} reduced Recycle for S elemental substance.

It can be seen from the above-mentioned technical solutions provided by the present invention that the catalyst with a spinel structure capable of simultaneous desulfurization and denitrification provided by the embodiments of the present invention and its preparation method and application uses activated carbon to support transition metal oxides and rare earth metals as additives, raw materials It has wide sources, easy acquisition and low cost; activated carbon has large specific surface area, good adsorption capacity, rich oxygen-containing functional groups, etc.; the measured specific surface area of the catalyst is 800-1500m ² /g.

Detailed ways

The embodiments of the present invention will be further described in detail below. The content not described in detail in the embodiments of the present invention belongs to the prior art known to those skilled in the art.

The catalyst with spinel structure capable of desulfurization and denitrification simultaneously of the present invention, its preferred embodiment is:

Including: the active component is two or three of CoO, Fe ₂ O ₃ , Al ₂ O ₃ , the auxiliary agent is one or two of CeO ₂ , Y ₂ O ₃ , and the carrier is activated carbon;

The active components of the catalyst form a spinel structure on the surface of the carrier.

The active components are two or three of CoO, Fe ₂ O ₃ , Al ₂ O ₃ , and the content of each component accounts for 5-15% of the mass of the carrier;

The auxiliary agent is one or both of CeO ₂ and Y ₂ O ₃ , and the content of each component accounts for 1-5% of the mass of the carrier.

The specific surface area of the catalyst: 800-1500m ² /g.

The above-mentioned preparation method of the catalyst with spinel structure capable of simultaneous desulfurization and denitrification of the present invention, its preferred embodiment is:

Include steps:

First of all, the catalyst activated carbon carrier should be pretreated: prepare a HNO ₃ solution with a concentration of 5-15%, impregnate overnight at room temperature according to a certain mass ratio of HNO ₃ and AC, wash until neutral, dry and cool for later use;

Then, add active component and auxiliary agent, make catalyst sample;

Afterwards, the catalyst sample was pre-sulfided: the sulfidation atmosphere was SO ₂ +CO, the sulfidation temperature was 400-600° C., and the sulfidation time was 1 h.

The application of the above-mentioned spinel structure catalyst capable of simultaneous desulfurization and denitrification of the present invention, its preferred embodiment is:

For simultaneous desulfurization and denitrification: CO is used as a reducing agent, and NO is reduced to N ₂ into the atmosphere by gas-solid catalytic reduction method, and SO ₂ is reduced to S simple substance for recycling.

The preparation method of the catalyst with spinel structure and capable of simultaneous desulfurization and denitrification at relatively low temperature and its application of the present invention. Compared with the prior art, the advantages of the present invention include the following points:

The raw materials used in the present invention have the advantages of wide source, easy acquisition and low cost;

Activated carbon has a large specific surface area, good adsorption capacity, and rich oxygen-containing functional groups, etc.; the measured specific surface area of the catalyst is 800-1500m ² /g;

Nitric acid pretreatment can effectively remove the ash on the surface of AC, dredge the pores, and further increase the specific surface area of the carrier. On the other hand, it can increase the adsorption and activation centers on the surface of the carrier;

Presulfurization can convert the active component metal oxide of the catalyst into metal sulfide, greatly reduce the reduction temperature required for the reaction, reduce the activation energy required for the reaction, and reduce energy consumption;

Spinel structure catalysts have better catalytic performance than conventional catalysts, and are very easy to generate lattice defects to generate more active sites and improve catalytic activity;

The flue gas itself contains unburned CO, which can be used as a reducing agent gas, which can reduce the cost and remove CO in the flue gas, so as to achieve the effect of treating waste with waste;

The catalyst of the invention can be made into various shapes such as honeycomb, which can reduce bed resistance and overcome dust blockage.

The preparation method of the catalyst of the present invention is an equal-volume impregnation method: take 20-40 mesh activated carbon particles, soak them overnight with 5-15% _HNO3 solution according to a certain mass ratio, and then wash until neutral and dry for later use.

Dissolve the nitric acid precursor of the corresponding active component according to the deionized water content of 1.5:1, let it stand in a constant temperature water bath at 40°C for 12h, then dry it in a blast drying oven for 12h, and finally bake it at 500°C for 4h in a nitrogen atmosphere , to obtain catalyst samples.

The prepared catalyst is subjected to presulfurization treatment, and the catalyst is presulfurized in a CO+SO ₂ atmosphere, the vulcanization temperature is between 400-600°C, and the vulcanization time is 1-3h.

The catalyst uses CO as the reducing agent, and adopts the gas-solid phase catalytic reduction method to reduce NO to N ₂ and discharge it into the atmosphere, and SO ₂ to S simple substance for recycling.

When the catalyst prepared by the present invention is applied to simultaneous desulfurization and denitrification, it includes the following contents:

With CO as the reducing agent gas, the gas composition in the reactor is NO:SO2:CO (volume fraction)=1:2:2.5.

In the normal pressure fixed bed reactor, the space velocity of simulated flue gas is 5000～10000h-1.

The operating temperature is 100-500°C.

Specific examples:

The following three specific examples are listed to illustrate the present invention, but the present invention is not limited to these examples.

Example 1, 10Fe ₂ O ₃ 6CoO3Y ₂ O ₃ /AC

Among them, Fe ₂ O ₃ accounts for 10% of the mass of the carrier, CoO accounts for 6% of the mass of the carrier, and Y ₂ O ₃ accounts for 3% of the mass of the carrier, that is, the total loading of active components and additives is 19%.

Take 500g of 20-40 mesh AC in a beaker, pretreat it with HNO ₃ at a certain concentration and a certain ratio (mass ratio to AC) for 12 hours, then wash until neutral and dry, cool to room temperature and set aside.

Accurately weigh 2.5299g Fe(NO ₃ ) ₃ 9H ₂ O, 1.0532g Co(NO ₃ ) ₂ 6H ₂ O, 0.3393g Y(NO ₃ ) ₃ 6H ₂ O, add 7ml of deionized water to dissolve to form a mixed solution; accurately weigh 5.0000g of pretreated AC, dip into the prepared mixed solution, soak at 40°C for 12h, then place at 110°C Dry it in a drying oven for 12 hours, and finally bake it in a nitrogen-protected tubular furnace at 500°C for 4 hours to obtain a catalyst sample.

The prepared catalyst was placed in a fixed-bed reactor at normal pressure, the gas composition was prepared as follows: 1000ppmSO ₂ , 2000ppmCO, and the rest was N ₂ , the presulfurization time was 1h, and the curing temperature was 550°C.

After the catalyst is presulfided, the composition of the simulated gas is: 1000ppmSO ₂ , 500ppmNO, 2500ppmCO, the rest is N ₂ , the space velocity is 6000h ^-1 , the catalyst dosage is 2mL, the T _90% is about 208°C, and the highest conversion rate is reached at 232°C. The _SO conversion was 100%, and the NO conversion was 100%.

Example 2, 10CoO15Al ₂ O ₃ 2CeO ₂ /AC

Among them, Al ₂ O ₃ accounts for 15% of the mass of the carrier, CoO accounts for 10% of the mass of the carrier, and CeO ₂ accounts for 2% of the mass of the carrier, that is, the total loading of active components and additives is 27%.

Take 500g of 20-40 mesh AC in a beaker, pretreat it with HNO ₃ at a certain concentration and a certain ratio (mass ratio to AC) for 12 hours, then wash until neutral and dry, cool to room temperature and set aside.

Accurately weigh 5.5166g Al(NO ₃ ) ₃ 9H ₂ Og, 2.5053Co(NO ₃ ) ₂ 6H ₂ O, 0.2523g Ce(NO ₃ ) ₂ 6H ₂ O, add 7ml of deionized water to dissolve to form a mixed solution; accurately weigh 5.0000g of pretreated AC, dip into the prepared mixed solution, soak at 40°C for 12h, and then place at 110 ℃ in a drying oven for 12 hours, and finally calcined at 500 ℃ for 4 hours in a nitrogen-protected tubular calcination furnace to obtain a catalyst sample.

The prepared catalyst was placed in a fixed-bed reactor at normal pressure, the gas composition was prepared as follows: 1000ppmSO ₂ , 2000ppmCO, and the rest was N ₂ , the presulfurization time was 1h, and the curing temperature was 550°C.

After the catalyst is presulfided, the composition of the simulated gas is: 1000ppmSO ₂ , 500ppmNO, 2500ppmCO, the rest is N ₂ , the space velocity is 6000h ^-1 , the catalyst dosage is 2mL, the T _90% is about 190°C, and the highest conversion rate is reached at 213°C. The _SO conversion was 100%, and the NO conversion was 100%.

Example 3, 10Fe ₂ O ₃ 10CoO2CeO ₂ /AC

Among them, Fe ₂ O ₃ accounts for 10% of the mass of the carrier, CoO accounts for 10% of the mass of the carrier, and CeO ₂ accounts for 2% of the mass of the carrier, that is, the total loading of active components and additives is 22%.

First take 500g of 20-40 mesh AC in a beaker, pretreat it with a certain concentration and a certain ratio (mass ratio to AC) of HNO ₃ for 12 hours, then wash until neutral and dry, cool to room temperature and set aside.

Accurately weigh 2.5299g Fe(NO ₃ ) ₃ 9H ₂ O, 2.5023g Co(NO ₃ ) ₂ 6H ₂ O, 0.2523g Ce(NO ₃ ) ₂ ·6H ₂ O, add 7ml of deionized water to dissolve to form a mixed solution; accurately weigh 5.0000g of pretreated AC, dip into the prepared mixed solution, soak at 40°C for 12h, and then place Dry it in a drying oven at 110°C for 12 hours, and finally bake it in a nitrogen-protected tubular furnace at 500°C for 4 hours to obtain a catalyst sample.

The prepared catalyst was placed in a fixed-bed reactor at normal pressure, the gas composition was prepared as follows: 1000ppmSO ₂ , 2000ppmCO, and the rest was N ₂ , the presulfurization time was 1h, and the curing temperature was 550°C.

After the catalyst is presulfided, the composition of the simulated gas is: 1000ppmSO ₂ , 500ppmNO, 2500ppmCO, the rest is _N2 , the space velocity is 6000h ^-1 , the catalyst dosage is 2mL, the T _90% is about 215°C, and the highest conversion rate is reached at 242°C. The _SO2 conversion rate was 99.67%, and the NO conversion rate was 100%.

The above is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person familiar with the technical field can easily conceive of changes or changes within the technical scope disclosed in the present invention. Replacement should be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be determined by the protection scope of the claims.

Claims (5)

1. a kind of energy simultaneous SO_2 and NO removal has spinel structure catalyst, which is characterized in that including：Active component be CoO, Fe₂O₃、Al₂O₃In two kinds or three kinds, auxiliary agent CeO₂、Y₂O₃In one kind or two kinds, carrier is activated carbon；

The active component of the catalyst forms spinel structure in carrier surface.

2. energy simultaneous SO_2 and NO removal according to claim 1 has spinel structure catalyst, which is characterized in that the work Property group is divided into CoO, Fe₂O₃、Al₂O₃In two or three, the content of each component accounts between the 5~15% of carrier quality； The auxiliary agent is CeO₂、Y₂O₃One or both of, the content of each component accounts between the 1~5% of carrier quality.

3. energy simultaneous SO_2 and NO removal according to claim 2 has spinel structure catalyst, which is characterized in that the catalysis The specific surface area of agent：800~1500m²/g。

4. a kind of energy simultaneous SO_2 and NO removal as claimed in claim 1,2 or 3 has the preparation method of spinel structure catalyst, It is characterized in that, including step：

First, catalyst activity high-area carbon to be pre-processed：HNO of the compound concentration 5~15%₃Solution is pressed at room temperature Certain HNO₃For quality with AC than steeped overnight, washing to neutrality is spare after dry cooling；

Then, active component and auxiliary agent is added, catalyst sample is made；

Later, presulfurization is carried out to the catalyst sample：Vulcanization atmosphere is SO₂+ CO, 400~600 DEG C of curing temperature, when vulcanization Between 1h.

5. a kind of energy simultaneous SO_2 and NO removal as claimed in claim 1,2 or 3 has the application of spinel structure catalyst, feature It is, is used for simultaneous SO_2 and NO removal：Using CO as reducing agent, NO is reduced to by N using gas and solid phase catalyzing reduction method₂Air is discharged into, SO₂S simple substance is reduced to be recycled.