KR20180054097A - Catalytic for inhibiting the N2O generation - Google Patents

Abstract

Disclosed is a catalyst which comprises: at least one zeolite having a CHA structure to be used in a selective catalytic reduction (SCR) device; and at least one zeolite having a ZSM-5 system structure. At least some portions of at least one zeolite with the type of the CHA structure includes copper (Cu), and at least some portions of at least one zeolite with the type of the ZSM-5 system structure includes iron (Fe).

Description

Catalyst for inhibiting N2O generation Catalyst for inhibiting the N2O generation [

The present invention relates to a selective catalytic reduction (SCR) catalyst based on zeolite, and more particularly, to a process for reducing NOx in exhaust gas of a diesel engine to nitrogen DeNOx performance relates to a side reaction (side reaction) to generate nitrous oxide (N ₂ O) N2O generation suppressing NOx reduction catalyst that minimizes the amount of to maintain.

Nitrous oxide (N ₂ O) is one of the representative global warming gases contained in the exhaust gas together with nitrogen oxides (NO x) as a colorless transparent gas which is generated when pyrolyzing ammonium nitrate.

Today, nitrogen monoxide in the exhaust gas emitted from diesel engines is removed by selective catalytic reduction (SCR) using a reducing agent such as ammonia, hydrogen, or carbon monoxide. Especially, in order to reduce nitrous oxide in the exhaust gas Iron-bearing zeolite catalysts are mainly used.

Among the most widely used zeolites are ZSM-5 catalysts, MFI (according to the IUPAC Committee's zeolite nomenclature, the same applies below), and MOR.

US Pat. Nos. 6,682,710 B1, US 2004/0192538 A1 and US 7,238,641 B2 disclose a method for removing nitrous oxide and nitrogen monoxide using a catalyst obtained by ion exchange of iron ions to FER zeolite.

When ammonia is used as a reducing agent, a temperature of 360 ° C or more is required to reduce nitrous oxide alone, and nitrogen monoxide and nitrous oxide are used as a reducing agent in the case of using a hydrocarbon as a reducing agent. A simultaneous reduction of nitrogen requires a temperature of 400 ° C or higher.

Therefore, it is necessary to develop a catalyst and a simultaneous abatement technology for lowering the temperature and the temperature for simultaneous reduction of nitrogen monoxide and nitrous oxide to the level of using a hydrocarbon as a reducing agent while simultaneously using ammonia as a reducing agent .

It is to be understood that the above-described techniques are intended to assist the understanding of the present invention, and are not to be construed as meaning that the present invention is well known in the art to which the present invention belongs.

B1 (2005.09.28) KR100937594 B1 (2010.01.12)

Accordingly, the present inventors have developed a new zeolite catalyst capable of effectively suppressing the generation of nitrous oxide (N ₂ O) by focusing on solving the limitations and problems of existing SCR catalysts in consideration of the above-mentioned matters As a consequence, the invention has been invented as a result of constant research.

Therefore, the technical problem and the object to be solved by the present invention is that to provide an N2O generation suppressing NOx reduction catalyst for to minimize the generation of nitrous oxide (N ₂ O).

Herein, the technical object and object to be solved by the present invention are not limited to the technical object and purpose mentioned above, and another technical object and purpose not mentioned can be understood by those skilled in the art from the following description.

Technical Solution According to an aspect of the present invention, there is provided a process for producing a zeolite having a CHA structure type for use in a selective catalytic reduction (SCR) process. And at least one zeolite of the MFI structure type, wherein at least a portion of the at least one zeolite of the CHA structure type comprises copper (Cu), at least a portion of the at least one zeolite of the MFI structure type is iron (Fe). ≪ / RTI >

Thus, the present invention provides an improved catalytic reduction device (SCR), wherein at least one zeolite of the CHA structure type comprises copper (Cu) and at least one zeolite of the MFI structure type comprises iron (Fe) The effect of minimizing the production of nitrous oxide (N ₂ O) can be obtained.

Further, in a preferred embodiment of the invention, the weight ratio of the CHA structure type of at least one zeolite for the MFI structure of at least one type of zeolite is 80 to 85: more effective nitrous oxide as made of an 20 to 15 range (N ₂ O) can be suppressed.

Further, in a preferred embodiment of the present invention, the amount of copper (Cu) in the at least one zeolite of the CHA structure type is 2.2 wt% to 7 wt% based on the total weight of the at least one zeolite of the CHA structure type, The amount of iron (Fe) in the at least one zeolite of the MFI structure type is in the range of 0.5 wt% to 10 wt%, so that the generation of nitrous oxide (N ₂ O) can be suppressed more effectively.

An embodiment of the present invention having the means and construction for solving the above object and the technical object of the present invention is characterized in that at least one zeolite of the CHA structure type comprises copper (Cu) and at least one zeolite of the MFI structure type (Fe), the effect of minimizing the generation of nitrous oxide (N ₂ O) in the field of selective catalytic reduction (SCR) can be obtained.

Here, the effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned can be clearly understood by those skilled in the art from the description of the claims.

1 is a graph showing an evaluation of the nitrogen oxide (NOx) nitrogen reduction rate performance according to the temperature change of the catalyst according to the embodiment of the present invention.
2 is a graph showing the amount of generated nitrous oxide (N ₂ O) according to the temperature change of the catalyst according to the embodiment of the present invention.

Hereinafter, embodiments according to the present invention will be described more specifically with reference to the accompanying drawings.

Prior to this, the following terms are defined in consideration of the functions of the present invention, and they are to be construed to mean concepts that are consistent with the technical idea of the present invention and interpretations that are commonly or commonly understood in the technical field of the present invention.

In the following description, well-known functions or constructions are not described in detail to avoid obscuring the subject matter of the present invention.

Here, when a part includes a constituent element, it means that the constituent element may include other constituent elements, not excluding the other constituent elements unless specifically stated otherwise.

The term " selective catalytic reduction " as abbreviated to "SCR " in the present invention means any catalytic process involving the reaction of a nitrogen oxide NOx with a reducing agent. In particular, SCR means a reduction reaction in which NOx is converted to its reduction product, preferably N2.

The term "reducing agent" means any suitable reducing agent for the SCR process, preferably ammonia and / or any ammonia precursor such as urea and / or ammonium carbamate is preferred and urea is preferably included in the ammonia precursor do.

In addition, the term "reducing agent" may further include hydrocarbon and / or hydrocarbon derivatives such as those found in automotive fuels and / or automotive exhaust gases, especially diesel fuels and / or diesel exhaust gases such as oxidized hydrocarbons .

The present invention relates to a catalyst comprising at least one zeolite of the CHA structure type and at least one zeolite of the MFI structure type for use in selective catalytic reduction (SCR), wherein at least one zeolite of the CHA structure type At least a portion of the at least one zeolite of the MFI structure type comprises iron (Fe).

That is, the present invention relates to an improved catalyst for use in the field of selective catalytic reduction (SCR) applications, wherein at least one zeolite of the CHA structure type comprises copper (Cu) and at least one zeolite of the MFI structure type comprises iron And the effect of minimizing the production of nitrous oxide (N ₂ O) can be obtained.

Fe-ZSM-5 is prepared by dissolving calculated Fe (NO3) 3 · 9H2O in 200 mL distilled water and adding 50 g of ZSM-5 type zeolite or BEA type zeolite to the solution for 6 hours (650 ° C for 6 hours) or stirring at 20 ° C for 24 hours, filtering and washing until the water completely evaporates at about 60 ° C. ≪ / RTI > for hours.

Preferably, the weight ratio of the at least one zeolite of the CHA structure type to the at least one zeolite of the MFI structure type is in the range of 80 to 85:20 to 15, thereby more effectively inhibiting the production of nitrous oxide (N ₂ O) .

Preferably, the amount of copper (Cu) in the at least one zeolite of the CHA structure type is from 2.2 wt% to 7 wt%, based on the total weight of the at least one zeolite of the CHA structure type, Since the amount of iron (Fe) in the zeolite is in the range of 0.5 wt% to 10 wt%, generation of nitrous oxide (N ₂ O) can be suppressed more effectively.

Any contemplated zeolite of the MFI or CHA structure type in the present invention can be used, respectively, as long as it exhibits the typical structural characteristics of its structural type. [As-Si-O] -MFI, [Fe-Si-O] -MFI, [Ga-Si-O] -MFI, AMS 1, LZ-105, monoclinic H-ZSM-5, Mutinaite, NU-4, NU-5, silicalite, Selected from the group consisting of TS-1, TSZ, TSZ-III, TZ-01, USC-4, USI-108, ZBH, ZKQ-1B, ZMQ-TB, organic free ZSM- Zeolite < / RTI >

According to a preferred embodiment of the invention, the at least one zeolite of the MFI structure type comprises ZSM-5.

[Al-As-O] -CHA, [Co-Al-PO] -CHA, [Mg-Al-PO] -CHA, [Si [Al-Si-O] -CHA, [Zn-As-O] -CHA, LAP-21, LINDE D, LINDE R, MeAPO-47, MeAPSO-47, KAPO-34, CoAPO-44, CoAPO-47, DAF-5, dehydrated Na-carbazite, GaPO-34, K- , Ni (Deta) 2-UT-6, Phi, SAPO-34, SAPO-47, SSZ-13, SSZ-62, UiO-21, Willhendersonite, ZK-14, ZYT- And a mixture of two or more thereof.

According to a preferred embodiment of the present invention, one or more zeolites of the CHA structure type are selected from the group consisting of carbazite, SSZ-13, LZ-218, Linde D, Linde R, Phi, ZK-14 and ZYT- At least one zeolite selected from the group consisting of mixtures of at least two species, and more preferably at least one zeolite of the CHA structure type comprises carbazite.

According to a further preferred embodiment of the invention, the at least one zeolite of the MFI structure type comprises ZSM-5 and the at least one zeolite of the CHA structure type is carbazite, SSZ-13, LZ- At least one zeolite selected from the group consisting of Linde R, Phi, ZK-14 and ZYT-6, and mixtures of two or more thereof.

More preferably, the at least one zeolite of the MFI structure type comprises ZSM-5 and the at least one zeolite of the CHA structure type comprises a carbazite. According to a particularly preferred embodiment, at least one zeolite of the MFI structure type comprises ZSM-5 and at least one zeolite of the CHA structure type is carbazate.

According to an embodiment of the present invention, at least a portion of one or more MFI type zeolites comprises iron, and at least a portion of one or more CHA type zeolites comprises copper. With regard to copper contained in at least part of the zeolite of at least one MFI type and copper contained in at least part of the zeolite of the at least one CHA type, said metal may be present in any conceivable manner, Respectively.

Therefore, according to the present invention, there is no particular limitation with regard to the oxidation state of iron and copper contained in the catalyst, and with respect to the manner in which this is included in each type of zeolite.

Preferably, iron and / or copper, more preferably both iron and copper, each indicate the oxidation state of the amount in each zeolite.

Iron and / or copper may also be included in the zeolite surface and / or in the porous structure of each zeolite structure. Alternatively or in addition to being supported on the zeolite surface and / or in its porous structure, the iron and / or copper may be included in the zeolite structure by, for example, isometric substitution.

According to a preferred embodiment, both iron and copper are supported both on the respective zeolite surface and / or in its porous structure, even more preferably on the respective zeolite surface and in its porous structure.

According to a preferred embodiment of the present invention, both iron and copper are included in at least a portion of at least one zeolite of the MFI and CHA structure types in their respective positive oxidation states, and that the iron and copper are contained within their porous structure And supported on the surface of each zeolite.

According to an embodiment of the present invention, it is preferred that at least one zeolite of the MFI structure type and / or at least one zeolite of the CHA structure type each contain both Al and Si in their structure and the MFI structure type zeolite and CHA It is further preferred that both of the zeolites of the structural type each contain both Al and Si in their structure.

It is therefore preferred that at least one of the zeolites, more preferably both zeolites, contain both Al and Si in their respective zeolite structures.

≪ Example 1 >

Silica to alumina ratio (SAR) of approximately 30 and a CHA structure type containing 4.2wt% of copper based on the total weight of the CHA zeolite type zeolite 85g / in ^3, the silica to alumina ratio of about 26 and zeolites of the MFI type 15 g / in ³ of MFI structure type zeolite containing 3.8 wt.% Iron based on the total weight of the catalyst composition and 0.3 g / in ³ of silica-alumina binder.

≪ Example 2 >

Silica to alumina ratio (SAR) of approximately 30, and CHA structure type of the zeolite 85g / in ^3, the silica to alumina ratio of about 26 containing the 7wt% copper, based on the total weight of the CHA type zeolite and the MFI type zeolite A catalyst composition was prepared comprising 15 g / in ³ of zeolite of MFI structure type containing 3.8 wt.% Iron based on total weight and 0.3 g / in ³ of silica-alumina binder.

≪ Comparative Example 1 &

Including alumina binder 0.3g / in ³ - silica to alumina ratio (SAR) of approximately 30, and CHA structure type of the zeolite 85g / in ^3, and silica containing 2.2wt% of copper based on the total weight of the CHA type zeolite Lt; / RTI >

≪ Comparative Example 2 &

Included are 85 g / in ³ of zeolite of CHA structure type and 0.3 g / in ³ of silica-alumina binder with a silica to alumina ratio (SAR) of approximately 30 and containing 4.2 wt% copper based on the total weight of the CHA type of zeolite Lt; / RTI >

≪ Comparative Example 3 &

Including 85 g / in ³ of zeolite of the CHA structure type containing about 7% by weight of copper based on the total weight of zeolite of CHA type and a silica-alumina ratio (SAR) of about 30 and 0.3 g / in ³ of silica- A catalyst composition was prepared.

<Performance evaluation>

1 shows the nitrogen oxide (NOx) nitrogen reduction rate results according to the temperature change from the NEDC (New European Driving Cycle) mode test of the catalyst compositions according to Examples 1 and 2 and Comparative Examples 1 to 3, respectively, and Fig. 2 (N ₂ O) according to the temperature change from the NEDC (New European Driving Cycle) mode test of the catalyst compositions according to Examples 1 and 2 and Comparative Examples 1 to 3.

The DeNOx performance of the SCR catalyst was evaluated in a temporary condition using NEDC (New European Driving Cycle).

For the test, the catalyst compositions according to Examples 1 and 2 and Comparative Examples 1 to 3 were filled in a 2.5 liter volume, each having a cell density of 400 cells per square inch and a wall thickness of 5.66 " 5.66 "x 6" flow-through honeycomb substrate.

The catalyst samples prepared in this way were then tested in an exhaust gas treatment system with a diesel oxidation catalyst (DOC) and a catalyzed soot filter (CSF) located upstream of the tested catalyst, respectively.

The results from the NEDC catalyst test are shown graphically in FIG. 1 and FIG.

That is, as shown in FIGS. 1 and 2, the catalyst of the present invention according to Examples 1 and 2, which includes a combination of CHA and MFI type zeolites, comprises a catalyst sample of Comparative Examples 1 to 3 containing only CHA type zeolite And clearly showed improved performance compared with the conventional method. In particular, as shown in Figure 1, the catalyst of the present invention produced a significantly higher level of conversion of NOx emissions as compared to the catalysts of the comparative examples.

When the volume of the catalyst was fixed and the flow rate was increased, the performance difference in the range of 200 to 300 ° C occurred. As the content of copper increased, the performance in the range of 200 to 300 ° C was excellent. However, ₂ O) was increased, and the Fe-ZSM-5 content decreased about 12% in the 200 ° C region, the 5% increase in the 500 ° C region and the N ₂ O production Respectively.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments or constructions. Various changes and substitutions may be made without departing from the spirit and scope of the invention. It will be obvious to those skilled in the art that the present invention can be widely applied to other embodiments.

Therefore, it is to be understood that modifications and variations of the features of the present invention are intended to be included within the spirit and scope of the present invention.

Claims (3)

At least one zeolite of the CHA structure type for use in selective catalytic reduction (SCR); And one or more zeolites of MFI structure type;
&Lt; / RTI &gt;
Wherein at least a portion of the at least one zeolite of the CHA structure type comprises copper (Cu), and at least a portion of the at least one zeolite of the MFI structure type comprises iron (Fe).
The method according to claim 1,
Wherein the weight ratio of the at least one zeolite of the CHA structure type to the at least one zeolite of the MFI structure type is in the range of 80 to 85:20 to 15.
3. The method according to claim 1 or 2,
Wherein the amount of copper (Cu) in the at least one zeolite of the CHA structure type is from 2.2 wt% to 7 wt%, based on the total weight of the at least one zeolite of the CHA structure type, and wherein the at least one zeolite of the MFI structure type (Fe) is in the range of 0.5 wt% to 10 wt%.

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