Synthesis of FER without an organic template

Abstract

A method for producing ferrierite (FER) zeolite without an organic template and ferrierite producible by the method. The method includes: (i) forming a reaction gel containing an aluminum source, sodium hydroxide and / or potassium hydroxide, and a silica sol; and (ii) heating the reaction gel at a temperature suitable for the growth of FER zeolite for a period suitable for the growth of FER zeolite. The reaction gel does not contain seed crystals. Further, the reaction gel does not contain an organic structure directing agent (OSDA). The ferrierite (FER) zeolite has the characteristics of: a) an SAR of 11 to 20, b) a BET surface area of 320 to 380 m 2 / g, and c) a micropore volume of 0.1 to 0.2 cm 3 / g.

Description

Technical Field

[0001] The present invention relates to ferrierite (FER) zeolite. The present invention also relates to a method for producing ferrierite zeolite. The present invention further relates to a catalyst article comprising ferrierite zeolite and a method for treating exhaust gas comprising contacting a catalyst article comprising FER zeolite with exhaust gas.

Background Art

[0002] Zeolites are crystalline or quasi-crystalline aluminosilicates constructed from repeating TO 4 tetrahedral units (or combinations of tetrahedral units), where T is most commonly Si and Al. These units are linked together to form a framework having regular cavities and / or molecular-sized channels within the crystal. Many types of synthetic zeolites have been synthesized, each having a unique framework based on the specific arrangement of its tetrahedral units. By IUPAC nomenclature, each topological type is assigned a unique three-letter code (e.g., "FER") by the International Zeolite Association (IZA) (http: / / www.iza-structure.org / databases / ).

[0003] Zeolites have many industrial applications, and zeolites with specific frameworks such as FER are known to be effective catalysts for treating combustion exhaust gases in industrial applications such as internal combustion engines, gas turbines, coal-fired power plants, etc. In one example, nitrogen oxides (NO x ) in the exhaust gas can be controlled by a so-called selective catalytic reduction (SCR) process, according to which NO x compounds in the exhaust gas are contacted with a reducing agent in the presence of a zeolite catalyst.

[0004] When prepared as an aluminosilicate composition, FER - type synthetic zeolites are generally produced using a structure directing agent (SDA), also commonly referred to as a "template" or "templating agent". The SDA used in the preparation of aluminosilicate FER - type materials is typically a complex organic molecule that induces or defines the molecular shape and pattern of the zeolite's framework. Generally, the SDA can be regarded as a mold from which the zeolite crystals are formed. After the crystals are formed, the SDA is removed from the internal structure of the crystals, leaving a molecularly porous aluminosilicate cage.

[0005] In typical synthetic techniques, solid zeolite crystals are formed from a reaction mixture containing skeletal reactants (e.g., a silica source and an alumina source), a source of hydroxide ions (e.g., NaOH), and an SDA. In such synthetic techniques, typically, over several days (depending on factors such as the crystallization temperature), the desired crystallization is achieved. Once crystallization is complete, the solid product containing the zeolite crystals is separated from the discarded mother liquor. This discarded mother liquor contains unused SDA, which often decomposes due to the harsh reaction conditions and unreacted silica.

[0006] The SDA used for FER zeolite synthesis is relatively expensive, contributing to a significant portion of the manufacturing cost of zeolites, and in addition, generates large amounts of waste. Furthermore, conventional methods for synthesizing zeolite FER have a relatively low yield based on the SDA (an important component of the reaction mixture), which also affects the manufacturing cost.

[0007] Synthesis of FER without an organic structure directing agent (OSDA) has been disclosed in various prior art documents, although zeolite seeds are used to assist the synthesis (see Chemical Engineering & Technology, 2002, 25, 273; JACS, 2012, 134, 11542; Microporous and Mesoporous Materials, 2014, 196, 89; and Journal of Materials Chemistry, 2011, 21, 9494). Other methods use templates to make FER (see International Publication No. 2020 / 021054 and Mesoporous Materials, 2020, 296, 109988). U.S. Patent No. 4,650,654 discloses the synthesis of FER zeolite without using an organic mineralizing agent and without using aqueous colloidal silica as a silica source. However, the FER produced by these methods does not exhibit improved catalytic performance.

[0008] The inventors have found that, compared to the prior art, the FER zeolite formed by the present invention has improved catalytic performance. Without being bound by theory, the specific method of preparing FER outlined herein enables control of the Al distribution in the FER framework, which is believed to have a positive effect on Fe species differentiation by promoting monomeric and dimeric active species.

[0009] There is still a need in the art for improved FER zeolites having improved catalytic performance, such as improved NOx conversion rates. Further, it is desirable to reduce the cost of the synthesis process, preferably by means that have less environmental impact. The present invention meets these needs, among others. SUMMARY OF THE INVENTION

[0010] One aspect of the present disclosure relates to a ferrierite (FER) zeolite having the following characteristics: a) an SAR of 11 to 20, b) 320 - 380 m 2 BET surface area of / g, c) 0.1 - 0.2 cm 3 micropore volume of / g.

[0011] Another aspect of the present disclosure is a method for producing ferrierite (FER) zeolite without an organic template, comprising (i) forming a reaction gel comprising an aluminum source, sodium hydroxide and / or potassium hydroxide, and a silica sol; (ii) heating the reaction gel at a temperature suitable for the growth of FER zeolite for a period suitable for the growth of FER zeolite; and relates to a method wherein the reaction gel does not contain seed crystals and further does not contain an organic structure-directing agent (OSDA).

[0012] Another aspect of the present disclosure relates to a catalyst article for treating exhaust gas, comprising the FER zeolite described herein or a FER zeolite obtainable by the method described herein.

[0013] Another aspect of the present disclosure relates to a method for treating exhaust gas, comprising contacting the exhaust gas with the catalyst article described herein.

Brief Description of the Drawings

[0014]

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Mode for Carrying Out the Invention

[0015] The first aspect of the present invention relates to a ferrierite (FER) zeolite having the following characteristics: a) SAR (SiO 2 / Al 2 O 3 ) of 11 to 20, b) a BET surface area of 320 to 380 m 2 / g, and c) a micropore volume of 0.1 to 0.2 cm 3 / g.

[0016] Here, the present disclosure will be further described. In the following sections, different aspects / embodiments of the present disclosure are defined in more detail. Each aspect / embodiment so defined can be combined with any other aspect / embodiment or multiple aspects / multiple embodiments unless otherwise explicitly indicated. In particular, any feature shown as being preferred or advantageous can be combined with any other feature or multiple features shown as being preferred or advantageous.

[0017] The FER zeolite according to the present invention can be a hydrogen form (H-type) FER zeolite. The term "H-type" FER zeolite refers to a FER zeolite having a framework charge substantially equilibrated by protons. In this type, the FER zeolite generally has H at the exchange sites +It contains a mixture with an alkali and / or alkaline earth cation. The H-form FER zeolite can be 90% or more, 95% or more, 96% or more, 97% or more, 98% or more, or 99% or more (by weight) in the H-form. The amount of the H-form FER zeolite can vary depending on the specific FER zeolite batch and the method used to form the FER zeolite.

[0018] Preferably, the SAR of the FER zeolite of the present invention is at most 20, preferably at most 19, preferably at most 18, more preferably at most 17, and even more preferably at most 16. Also, in some embodiments, the SAR of the CHA zeolite is preferably at least 11 or at least 12. In some embodiments, the SAR of the CHA zeolite is preferably from 11 to 20, from 12 to 19, from 13 to 18, from 14 to 17, or from 15 to 16, for example, from 11 to 19, from 11.5 to 17.5, or from 12 to 17.

[0019] As used herein, SAR (SiO 2 / Al 2 O 3 ) refers to the synthesized zeolite crystals and not the starting synthesis gel. The SAR of the zeolite can be determined by conventional analysis. This ratio is intended to be as close as possible to the ratio in the rigid atomic framework of the zeolite crystals and to exclude silicon or aluminum in the channels, in the binder, or in the cationic or other forms. Since it can be difficult to directly measure the silica to alumina ratio (SAR) of the zeolite after combination with a binder material, especially an alumina binder, these silica to alumina ratios are for the SAR zeolite itself, i.e., before combining the zeolite with other catalyst components.

[0020] In combination with the desired SAR, the present invention provides 320 - 380 m 2 / g, preferably 330 - 375 m 2 / g, for example 340 - 370 m 2 / g, 345 - 365 m 2 / g, 348 - 364 m2 / g. 349 - 363 m 2 / g, 350 - 360 m 2 / g, 351 - 359 m 2 / g, 352 - 358 m 2 / g or 353 - 357 m 2 It is possible to provide a FER zeolite having a BET surface area of / g.

[0021] In combination with the desired SAR, the present invention provides a FER zeolite having a micropore volume of 0.1 - 0.2 cm 3 / g, preferably 0.11 - 0.18 cm 3 / g, or more preferably 0.11 - 0.15 cm 3 / g, for example, 0.11 - 0.14 cm 3 / g or 0.12 - 0.13 cm 3 / g. In a further embodiment, the micropore volume of the FER zeolite is 0.12 cm 3 / g.

[0022] Alone or in combination with any of the desired features described herein, the present invention provides a FER zeolite having a mesopore volume of 0.01 - 0.1 cm 3 / g, preferably 0.015 - 0.08 cm 3 / g, more preferably 0.02 - 0.05 cm 3 / g, 0.025 - 0.045 cm 3 / g, for example 0.03 - 0.04 cm 3 / g. In a preferred embodiment, the mesopore volume is 0.01 - 0.06 cm 3 / g, for example 0.015 - 0.05 cm 3 / g.

[0023] Alone or in combination with any of the desired features described herein, the present invention provides a FER zeolite having a value less than 35 m 2 / g, preferably 30 m 2 / g or less, more preferably 25 m 2FER zeolites having an external surface area of 24 m 2 / g or less, 22 m 2 / g or less, 21 m 2 / g or less, 20 m 2 / g or less, 19 m 2 / g or less, 18 m 2 / g or less, 17 m 2 / g or less, 16 m 2 / g or less, 15 m 2 / g or less, 14 m 2 / g or less, 12 m 2 / g or less, or 10 m 2 / g may be obtained. In certain embodiments, the FER zeolite has an external surface area of 0 to 35 m 2 / g, 1 to 30 m 2 / g, 2 to 25 m 2 / g, or 3 to 24 m 2 / g, 4 to 22 m 2 / g, 5 to 20 m 2 / g, 6 to 18 m 2 / g, 7 to 17 m 2 / g, 8 to 15 m 2 / g, or 9 to 12 m 2 / g, for example, 8 to 25 m 2 / g, for example, 9 to 20 m 2 / g, 10 to 19 m 2 / g, 11 to 18 m 2 / g, 12 to 17 m 2 / g, or 13 to 16 m 2 / g. In preferred embodiments, the external surface area is 10 to 20 m 2 / g.

[0024] The external surface area can be measured using any conventional technique in the art. For example, according to the Brunauer-Emmett-Teller (BET) method, Ar or N in samples activated at 87 K or 77 K, respectively 2It is by measuring the adsorption isotherm. Before measurement, the sample is heated under vacuum to remove physically adsorbed water. The pore size distribution is measured by the nonlocal density functional theory (NLDFT). The external surface area is calculated by the difference between the apparent BET surface area and the micropore surface area.

[0025] Preferably, the FER zeolite has a crystallinity of more than 95%, for example, more than 97% or more than 98%. The FER zeolite may not substantially contain other crystal phases and is typically not a twinned crystal of two or more framework types. As used herein, the term "substantially free of" means that the zeolite contains less than about 5, 4, 3, 2, 1, 0.5, 0.1, 0.05, or 0.01 weight percent of the framework impurities or all impurities named above.

[0026] Preferably, the FER zeolite has a flake-like morphology. That is, the zeolite preferably has a morphology in which the zeolite crystals have substantially planar, i.e., one-dimensional or two-dimensional shapes, in contrast to particles having a three-dimensional shape, i.e., disk-like or plate-like particles.

[0027] Preferably, the FER zeolite has an average longest edge crystal size of 1 micrometer or less, preferably 0.9 micrometer or less. In some embodiments, the FER zeolite can have an average longest edge crystal size of 0.01 to 1 micrometer, such as 0.1 to 0.9 micrometer, 0.2 to 0.8 micrometer, 0.25 to 0.7 micrometer, 0.3 to 0.6 micrometer, or 0.4 to 0.5 micrometer. Such average crystal sizes can be determined using standard microscopy techniques such as scanning electron microscopy (SEM). The measurement is performed on a statistically meaningful portion of the generated zeolite.

[0028] In a further embodiment, the six-coordinate Al is 15% or less, for example, less than 15%, less than 14%, less than 12%, less than 10%. In some embodiments, the six-coordinate Al is 3 - 15%, 3.5 - 14%, 4 - 13%, 5 - 12%, 6 - 10%. The six-coordinate Al is 27 It can be determined using standard techniques such as Al solid-state MAS-NMR. The spectrum can be quantified by integrating over a range of 80 ppm to -30 ppm covering all observed isotropic peaks and a range of 15 ppm to -30 ppm covering only the six-coordinate Al. The measurement can be performed on the hydrogen form of the FER zeolite.

[0029] In a preferred embodiment, the FER zeolite according to the present invention does not contain or substantially does not contain one or more of the following: fluorine, fluorine-containing compounds, and fluoride ions. Preferably, the FER zeolite according to the present invention does not contain or substantially does not contain all of the following: fluorine, fluorine-containing compounds, and fluoride ions. "Substantially does not contain" means that the zeolite contains no more than 0.1%, for example, less than 0.08%, less than 0.05%, less than 0.03%, less than 0.02%, less than 0.01%, less than 0.005%, less than 0.001% (by weight based on the total weight of the zeolite) of the undesirable components.

[0030] In a further aspect of the present disclosure, a method for producing a ferrierite (FER) zeolite, (i) forming a reaction gel comprising an aluminum source, sodium hydroxide and / or potassium hydroxide, and a silica sol; (ii) heating the reaction gel at a temperature suitable for the growth of the FER zeolite for a period suitable for the growth of the FER zeolite; comprising relates to a method wherein the reaction gel does not contain seed crystals and further does not contain an organic structure-directing agent (OSDA).

[0031] It is particularly preferred that the method described herein is for producing the FER zeolite described herein.

[0032] The method for preparing ferrierite can include forming a reaction gel, sometimes simply referred to as a reaction mixture. Such reaction gels are well-known in the technical field of zeolite synthesis. The reaction gel for the method of preparing ferrierite contains an aluminum source, sodium / potassium hydroxide, and a silica sol. Examples of the aluminum source include sodium aluminate, aluminum salts such as aluminum sulfate, aluminum nitrate, aluminum chloride, aluminum hydroxide, aluminum alkoxide, and alumina, preferably one or more of sodium aluminate and aluminum hydroxide. The silica sol is a colloidal suspension of silica in water. In a preferred embodiment, the reaction gel contains sodium aluminate, sodium hydroxide, and a silica sol solution.

[0033] As is known in the art, the reaction composition can also be described in terms of the equivalents of SiO 2 , Al 2 O 3 , M 2 O (where M is an alkali metal or an alkaline earth metal), and H 2 O present in the reaction gel. In other words, the reaction gel composition can be described by the ratio: Al 2 O 3 equivalent molar amount (1 mole) normalized to the ratio: Al 2 O 3 : aSiO 2 : bM 2 O: cH 2 O. As will be understood, the scale of the reaction and the absolute molar amounts can vary.

[0034] In some embodiments, the amount of M 2 O equivalents, i.e., the total amount of all M 3 O equivalents (Na 2 O and K 2 O), relative to the molar amount of Al 2 O equivalents, i.e., the total amount of all M 2One or both of O may be present) is at least 1 mole, preferably 1 to 10 moles, more preferably 2 to 8 moles, even more preferably 2.2 to 6 moles. Similarly, "b" in the gel composition can be any of these ranges or values. In some particularly preferred embodiments, Al in the reaction gel 2 O 3 The molar amount of M equivalent to the molar amount of 2 O equivalent is 1 to 8 moles. When a smaller amount of M 2 O equivalent is preferred, the amount of M 2 O equivalent is preferably 1.5 to 7 moles, preferably 2 to 6 moles. M can be selected from one or more alkali metals or alkaline earth metals. Preferably, M is selected from one or more from the list including (e.g., consisting of) Na, K, Li, Cs, Sr, and Ba. In a preferred embodiment, M is Na.

[0035] In some embodiments, relative to the molar amount of Al 2 O 3 equivalent, the gel preferably contains at least 10 moles, preferably 10 to 50 moles, 12 to 40 moles, or 13 to 35 moles of SiO 2 equivalent. Similarly, "a" in the gel composition can be any of these ranges or values. For example, in some embodiments, a larger amount of SiO 2 equivalent such as 14 to 33 moles, preferably 15 to 30 moles, or 20 to 25 moles is preferred. In some preferred embodiments, about 20 moles of SiO 2 equivalent is preferred.

[0036] In some embodiments, Al 2 O 3Preferably, the gel contains water in an amount of at least 700 moles, preferably 750 to 4000 moles, relative to the molar amount of the equivalents. Similarly, "c" in the gel composition can be any of these ranges or values. For example, in some embodiments, larger amounts of water, such as 800 to 3000 moles, preferably 900 to 1250 moles, for example about 1000 moles, etc., are preferred (especially when larger amounts of SiO 2 equivalents or M 2 O equivalents are added).

[0037] In some embodiments, the reaction gel composition has a Na 2 O / SiO 2 ratio of 0.05 to 0.3, such as 0.06 to 0.25, 0.07 to 0.22, 0.08 to 0.2, 0.09 to 0.19, 0.1 to 0.18, 0.11 to 0.17, 0.12 to 0.16, 0.13 to 0.17, or 0.14 to 0.16. In preferred embodiments, the Na 2 O / SiO 2 molar ratio is 0.08 to 0.21, 0.09 to 0.2, or 0.1 to 0.18.

[0038] In some embodiments, the reaction gel composition has a K 2 O / (K 2 O + Na 2 O) ratio of less than 0.1, such as less than 0.099, less than 0.095, less than 0.09, less than 0.08, less than 0.07. In some embodiments, the reaction gel has a K 2 O / (K 2 O + Na 2 O) ratio of 0 to 0.099, 0.01 to 0.095, or 0.015 to 0.09.

[0039] In some embodiments, the reaction gel composition has an H 2 O / SiO 2 ratio of 45 to 110, such as 50 to 100.

[0040] The reaction gel for preparing the ferrierite is a gel that does not contain an organic structure-directing agent, that is, the reaction gel does not contain an organic structure-directing agent (OSDA). "Not containing an organic structure-directing agent" means that the reaction gel contains less than 1% by weight of the organic structure-directing agent, for example, less than 0.9% by weight, less than 0.5% by weight, less than 0.3% by weight, less than 0.2% by weight, less than 0.1% by weight, or less than 0.01% by weight of the organic structure-directing agent, based on the total weight of the reaction gel. In a preferred embodiment, the organic structure-directing agent contained in the reaction gel is 0% by weight.

[0041] A particular advantage of this method is that the inventors have found that this method does not require the use of seed crystals to form the desired FER zeolite. Thus, the reaction gel does not contain seed crystals (e.g., FER seed crystals). "Not containing seed crystals" means that the reaction gel contains less than 0.1% of seed crystals, for example, less than 0.08% by weight, less than 0.05% by weight, less than 0.03% by weight, less than 0.02% by weight, less than 0.01% by weight, less than 0.005% by weight, less than 0.001% by weight of seed crystals, based on the total weight of the reaction gel. In a preferred embodiment, the seed crystals contained in the reaction gel are 0% by weight.

[0042] In a preferred embodiment, the reaction gel does not contain or substantially does not contain one or more of the following: fluorine, fluorine-containing compounds, and fluoride ions. Preferably, the reaction gel does not contain or substantially does not contain all of the following: fluorine, fluorine-containing compounds, and fluoride ions. "Substantially does not contain" means that the zeolite contains less than 0.1% by weight, for example, less than 0.08% by weight, less than 0.05% by weight, less than 0.03% by weight, less than 0.02% by weight, less than 0.01% by weight, less than 0.005% by weight, less than 0.001% by weight (by weight based on the total weight of the zeolite) of undesirable components.

[0043] In a particularly preferred embodiment of the present invention, the reaction gel consists of an aluminum source, sodium hydroxide, silica sol, and water, and optionally, further sodium salts and / or potassium salts.

[0044] The heating of the reaction gel for preparing the ferrierite is carried out at a temperature and for a period suitable for the growth of the FER zeolite. Preferably, the temperature at which the reaction gel is heated over such a suitable period is 100 °C to 220 °C, more preferably 110 °C to 210 °C, 120 °C to 200 °C, 130 °C to 190 °C, or even 140 °C to 180 °C. The period during which the reaction gel is heated to a suitable temperature is preferably at least 10 hours, more preferably 20 hours to 8 days, 1 day to 7 days, for example 1 to 6 days. It is particularly preferred to heat the reaction gel to these temperatures and hold it at these temperatures for these periods, for example, hold it at a temperature of 100 °C to 220 °C for at least 10 hours.

[0045] Preferably, the FER zeolite product obtained by heating the reaction gel over such temperatures and periods is recovered by typical vacuum filtration. Preferably, the filtered product is washed with demineralized (also known as deionized) water used to remove the residual mother liquor. Preferably, the zeolite product is washed until the conductivity of the filtrate is less than 0.1 mS. Preferably, the filtered and washed product is then dried at a temperature above 100 °C, preferably about 120 °C. The FER zeolite product can be filtered by vacuum filtration and washed with demineralized water.

[0046] The method of the present invention may further include one or more steps for removing metal ions such as alkali metal ions from within the FER ion exchange sites. Typically, the alkali metal ions are exchanged with non-metal cations such as ammonium ions (NH 4 + ) or protons (H + ). The ion exchange to ammonium ions can be carried out by mixing the zeolite with an aqueous ammonium sulfate solution and subsequently stirring. Further, the ion exchange to protons can be carried out by ion-exchanging the zeolite with ammonia and calcining it at a temperature of about 450 to 600 °C, preferably about 500 to 550 °C, for about 25 to 40 hours, for example about 30 to 35 hours, preferably in an oxygen-containing environment such as air.

[0047] The FER zeolite of the present invention can be used as a catalyst and / or an adsorbent. In a preferred example, one or more catalytically active metals or metals that improve the performance of the catalyst composition in other ways (collectively, "enhancing metals") are exchanged into the FER zeolite. The exchange of the enhancing metals can be achieved in situ after zeolite synthesis via incipient wetness, solid-state ion exchange, or during the preparation of the washcoat slurry, or during the synthesis process by adding the enhancing metals to the reaction mixture. Any one of the above-mentioned metals can be used in combination with any of the other methods to incorporate, for example, two or more enhancing metals into the zeolite.

[0048] Preferably, the enhancing metal is a non-framework metal. As used herein, "non-framework metal" preferably exists as ionic species within the zeolite pores and / or on at least a portion of the zeolite surface, does not contain aluminum, and does not contain atoms that constitute the framework of the zeolite. Preferably, the presence of the enhancing metal facilitates the treatment of exhaust gases such as those from diesel engines, including processes such as NO x reduction, NH 3 oxidation, and NO x storage.

[0049] Reinforcing metals include certain transition metals such as copper (Cu), iron (Fe), manganese (Mn), nickel (Ni), molybdenum (Mo), and zinc (Zn), with copper and / or iron being preferred, and copper being most preferred. Specific enhancing metals are noble metals such as gold (Au) and silver (Ag), and furthermore, platinum group metals such as platinum (Pt), palladium (Pd), ruthenium (Ru), and rhodium (Rh). Additionally, the enhancing metal can be one or more rare earth metals such as cerium (Ce), praseodymium (Pr), neodymium (Nd), europium (Eu), erbium (Er), gadolinium (Gd), ytterbium (Yb), and yttrium (Y), which can be used to improve catalytic performance, especially when used in combination with transition metals. (Yttrium can be described as a transition metal, but in this specification, it is referred to as a rare earth metal due to its lanthanide-like properties.)

[0050] One or more enhancing metals are preferably present at a concentration of about 0.1 to about 10 weight percent (wt%), for example, about 0.5 wt% to about 5 wt%, about 0.5 to about 1 wt%, about 1 to about 1.5 wt%, about 1 to about 2 wt%, about 1 to about 5 wt%, about 2.5 wt% to about 3.5 wt%, and about 3.5 to about 5 wt%, based on the total weight of the zeolite. In embodiments utilizing two or more enhancing metals, each metal can independently be present in the amounts described above.

[0051] When copper, iron, or a combination thereof is used as the enhancing metal, it is preferably present at a concentration of transition metal in the FER zeolite material of about 1 to about 5 weight percent, more preferably about 2.5 to about 4.5 weight percent, based on the total weight of the FER zeolite.

[0052] In a further embodiment, the method of preparing the ferrierite can further include a step of loading iron onto the FER zeolite formed in step ii) by ion exchange, for example, using an iron source selected from an iron source such as iron(II) chloride or ammonium ferric oxalate. For example, the method of preparing the ferrierite can further include a step iii) of loading iron onto the FER zeolite by ion exchange with an iron source selected from iron(II) chloride or ammonium ferric oxalate.

[0053] In a further embodiment, the ferrierite zeolite described herein or obtained from the methods described herein can be present in a catalyst composition.

[0054] The catalyst composition can contain a noble metal such as Pt, Pd, Ru, Rh, Os, Ir, Ag, or Au. In other embodiments, the catalyst composition may essentially not contain any noble metal.

[0055] Alternatively, the catalyst composition may essentially not contain noble metals other than palladium, platinum, and rhodium, may essentially not contain noble metals other than palladium and platinum, or may essentially not contain noble metals other than palladium.

[0056] The catalyst composition may essentially not contain any non-framework transition metals. Alternatively, the catalyst composition may essentially not contain non-framework transition metals other than copper and iron. In certain examples, the catalyst essentially does not contain any non-framework transition metals other than copper.

[0057] In a further aspect of the present invention, there is provided a catalytic article for treating exhaust gas, the catalytic article comprising a FER zeolite as described herein. The catalytic article can comprise a FER zeolite as described herein disposed on and / or within a substrate. The substrate can be a metal plate or a honeycomb. The FER zeolite as described herein can be a washcoat on a substrate, such as a honeycomb. The honeycomb can be an extruded catalyst, a wall flow filter, or a flow through honeycomb.

[0058] According to a further aspect, there is provided a method for treating exhaust gas, the method comprising contacting the exhaust gas with a catalytic article as described herein. The method for treating exhaust gas can further comprise contacting an exhaust gas containing NO x and / or NH 3 with a catalytic article as described herein to selectively reduce at least a portion of the NO x to N 2 and H 2 O and / or to further oxidize at least a portion of the NH 3 . Thus, in one embodiment, the catalytic article can be formulated to be advantageous for the reduction of nitrogen oxides by a reducing agent (i.e., an SCR catalyst). Examples of such reducing agents include hydrocarbons (e.g., C3-C6 hydrocarbons), as well as nitrogenous reducing agents such as ammonia and hydrazine ammonia, or any suitable ammonia precursor such as urea ((NH 2 ) 2 CO), ammonium carbonate, ammonium carbamate, ammonium bicarbonate, or ammonium formate. Preferably, the catalyst has a low N 2 O selectivity. The N 2 O selectivity is defined as the number of moles of N 2 O formed divided by the number of moles of NO x converted (NO x is defined as NO and NO 2 ). A lower N 2 O selectivity is desirable because it is necessary to reduce N 2 O formation.

[0059] The method for treating exhaust gas is to remove NO x Reduction of the compound or NH 3 A method for oxidizing NO in a gas x Compound and / or NH 3 for a period of time sufficient to reduce the concentration of NO x The method may include a method comprising contacting a catalyst article comprising a FER zeolite as described herein with a gas for catalytic reduction of a compound. In certain embodiments, a catalyst article (e.g., a catalyst article comprising a FER zeolite as described herein) is provided having an ammonia slip catalyst disposed downstream of a selective catalytic reduction (SCR) catalyst. In such embodiments, the ammonia slip catalyst oxidizes at least a portion of any nitrogen-based reductant not consumed by the selective catalytic reduction process. For example, in some embodiments, the ammonia slip catalyst is disposed on the outlet side of a wall-flow filter and the SCR catalyst is disposed on the upstream side of the filter. In some other embodiments, the ammonia slip catalyst is disposed on a downstream end of a flow-through substrate and the SCR catalyst is disposed on an upstream end of the flow-through substrate. In other embodiments, the ammonia slip catalyst and the SCR catalyst are disposed on separate bricks in the exhaust system. These separate bricks may be adjacent and in contact with each other or may be separated by a certain distance, provided that they are not in fluid communication with each other and provided that the SCR catalyst brick is not disposed upstream of the ammonia slip catalyst brick.

[0060] In certain embodiments, the SCR and / or AMOX process is carried out at a temperature of at least 150°C. In another embodiment, the process is carried out at a temperature of about 160°C to about 750°C. In certain embodiments, the temperature range is from about 175 to about 550°C. In another embodiment, the temperature range is from 175 to 400°C. In yet another embodiment, the temperature range is from 450 to 900°C, preferably from 500 to 750°C, from 500 to 650°C, from 450 to 550°C, or from 650 to 850°C. Embodiments utilizing temperatures above 450°C are particularly useful for treating exhaust gases from large and small diesel engines, where the engine is equipped with an exhaust system including a (optionally catalyzed) diesel particulate filter, which is actively regenerated, for example, by injecting hydrocarbons into the exhaust system upstream of the filter, and the FER zeolite described herein (or a catalyst article comprising the FER zeolite described herein) is located downstream of the filter.

[0061] According to another aspect of the invention, a method for reducing NO x compounds and / or oxidizing NH 3 in a gas, the method comprising contacting a catalyst article comprising the FER zeolite described herein with the gas for a time sufficient to reduce the concentration of NO x compounds in the gas, is provided. The method of the invention comprises the following steps: (a) accumulating and / or combusting soot in contact with the inlet of a catalytic filter; (b) introducing a nitrogenous reducing agent into the exhaust gas stream and then contacting it with the catalytic filter, preferably without an intervening catalytic step involving the treatment of NO x and a reductant; (c) generating NH x on an NO x adsorption catalyst or a lean NO 3 trap, preferably generating such NH 3 for use as a reducing agent in a downstream SCR reaction; (d) contacting the exhaust gas stream with a DOC to oxidize hydrocarbon-soluble organic components (SOF) and / or carbon monoxide to CO 2 and / or NO to NO 2oxidize and then use it to oxidize particulate matter in a particulate matter filter and / or reduce particulate matter (PM) in the exhaust gas, (e) contacting the exhaust gas with one or more flow-through SCR catalyst devices in the presence of a reducing agent to reduce the NO x concentration in the exhaust gas, and (f) preferably contacting the exhaust gas with an ammonia slip catalyst downstream of the SCR catalyst to oxidize most but not all of the ammonia and then discharging the exhaust gas to the atmosphere or passing the exhaust gas through a recirculation loop and then flowing / rerouting the exhaust gas into the engine, which may include one or more of the steps.

[0062] In another embodiment, all or at least a portion of the nitrogen-based reducing agent for consumption in the SCR process, particularly NH 3 is placed upstream of the SCR catalyst, such as the SCR catalyst of the present invention disposed on a wall flow filter, by a NO x adsorption catalyst (NO X adsorber catalyst, NAC), lean NO x trap (lean NO X trap, LNT), or NO x storage / reduction catalyst (NO X storage / reduction catalyst, NSRC). NAC components useful in the present invention include a combination of a basic material (including oxides of alkali metals, alkaline earth metals, and combinations thereof, such as alkali metals, alkaline earth metals, or rare earth metals) and a noble metal (such as platinum), and optionally a reduction catalyst component such as rhodium. Specific types of basic materials useful for NAC include cesium oxide, potassium oxide, magnesium oxide, sodium oxide, calcium oxide, strontium oxide, barium oxide, and combinations thereof. The noble metal is preferably present at about 10 to about 200 g / ft 3 , for example, 20 to 60 g / ft 3 . Alternatively, the noble metal of the catalyst is present at about 40 to about 100 g / ft 3It is characterized by an average concentration that may be present.

[0063] Under certain conditions, during periodic rich regeneration events, NH 3 can be generated on the NO x adsorption catalyst. The SCR catalyst downstream of the NO x adsorption catalyst can improve the NO x reduction efficiency of the entire system. In the combined system, the SCR catalyst can store the NH 3 released from the NAC catalyst during rich regeneration events, and utilize the stored NH 3 to selectively reduce some or all of the NO x passing through the NAC catalyst during normal lean operating conditions.

[0064] The exhaust gas treatment method described herein can be implemented for exhaust gases derived from combustion processes, such as exhaust gases from internal combustion engines (either mobile or stationary), gas turbines, and coal or oil-fired power plants. Also, this method can be used to treat gases from industrial processes such as refining, including gases from heaters and boilers in refineries, furnaces, chemical processing industries, coke ovens, municipal waste plants, and incinerators. In a specific embodiment, this method can be used to treat exhaust gases from lean-burn internal combustion engines of vehicles, such as diesel engines, lean-burn gasoline engines, or engines powered by liquefied petroleum gas or natural gas.

[0065] In a further aspect of the present invention, there is provided a system for treating exhaust gas containing NOx, the system comprising the catalyst article and the reductant source described herein, with the reductant source being upstream of the catalyst article.

[0066] In certain embodiments, the system is for treating exhaust gases generated by a combustion process, such as exhaust gases from an internal combustion engine (either mobile or stationary), a gas turbine, a power generation plant fueled by coal or oil, etc. Such a system includes a catalyst article comprising the FER zeolite described herein and at least one additional component for treating the exhaust gas, and the catalyst article and the at least one additional component are designed to function as a coherent unit.

[0067] In a particular embodiment, the system comprises a catalyst article comprising the FER zeolite described herein, a conduit for directing the flowing exhaust gas, and a source of nitrogenous reducing agent disposed upstream of the catalyst article. The system may comprise a controller for metering a nitrogenous reducing agent into the flowing exhaust gas only if it is determined that the zeolite catalyst can catalyze NO x reduction at a desired efficiency or greater at temperatures above 100 °C, above 150 °C, or above 175 °C, etc. For metering the nitrogenous reductant, it can be calculated at 1:1 NH 3 / NO and 4:3 NH 3 / NO 2 and adjusted so that 60% - 200% of the theoretical ammonia is present in the exhaust gas flowing into the SCR catalyst.

[0068] In another embodiment, the system comprises an oxidation catalyst (e.g., a diesel oxidation catalyst (DOC)) for oxidizing nitric oxide in the exhaust gas to nitrogen dioxide, which may be located upstream of the location where the nitrogenous reducing agent is metered into the exhaust gas. In one embodiment, for example, at an exhaust gas temperature of 250 °C - 450 °C at the oxidation catalyst inlet, the NO to NO 2Adapt the oxidation catalyst so that a gas flow that has a volume ratio and that flows into the SCR zeolite catalyst is produced. The oxidation catalyst can include at least one platinum group metal, such as platinum, palladium, or rhodium (or some combination thereof), coated on a flow-through monolith substrate. In one embodiment, the at least one platinum group metal is platinum, palladium, or a combination of both platinum and palladium. The platinum group metal can be supported on a high surface area washcoat component such as alumina, a zeolite such as aluminosilicate zeolite, silica, non-zeolite silica alumina, ceria, zirconia, titania, or a mixed or composite oxide containing both ceria and zirconia.

[0069] In a further embodiment, a suitable filter substrate is located between the oxidation catalyst and the SCR catalyst. The filter substrate can be selected from a wall-flow filter, a flow-through filter, a particulate filter, a catalytic filter, and is preferably a wall-flow filter. For example, when the filter is catalyzed with an oxidation catalyst, preferably, the metering location of the nitrogenous reducing agent is located between the filter and the zeolite catalyst. Alternatively, when the filter is not catalyzed, the means for metering the nitrogenous reducing agent may be located between the oxidation catalyst and the filter.

Examples

[0070] Examples 1-8 and Comparative Examples 1-3 First, a synthesis gel was prepared by dissolving an aluminum source such as sodium aluminate (52.75% Al 2 O 3 , 42.47% Na 2 O, 4.70% H 2 O) and / or aluminum hydroxide (55.80% Al 2 O 3 ) in sodium hydroxide (50.0% aqueous solution) and deionized (DI) water. If necessary, potassium was added using potassium hydroxide (45.0% aqueous solution) and / or potassium sulfate (99%) as raw materials. Then, while stirring vigorously, finally, a silica sol (40% SiO2 ) was added. The gel compositions are listed in Table 1. For crystallization, the gel was heated at 180 °C for 1 to 6 days at 200 - 400 rpm. After crystallization, the solid phase was filtered, washed thoroughly with DI water, and dried at 120 °C. To obtain H-type FER zeolite, the sample was ion-exchanged at 100 °C using 5% ammonium sulfate solution and then activated at 550 °C for 2 hours at a heating rate of 1 °C / min.

[0071] Each product was analyzed by powder XRD and SEM. The powder XRD of H-type FER zeolite from Examples 2 and 7 and Comparative Examples CE2 and CE3 is shown in Figure 1. The SEM image of the product from Example 2 is shown in Figure 2. The 27 Al-solid MAS-NMR spectrum of H-type FER zeolite from Example 2 is shown in Figure 3. The SAR determined by X-ray fluorescence spectroscopy (XRF), the external surface area, the micropore volume and mesopore volume determined by Ar adsorption isotherm are listed in Table 1.

[0072]

Table 1

[0073] Example 2: Selective Catalytic Reduction (SCR) Performance The H-type FER zeolites from Example 2 and 7 and Comparative Examples CE2 and CE3 were impregnated using the required amount of ammonium ferric oxalate dissolved in deionized water. The Fe-impregnated zeolites were dried overnight at 100 °C and then calcined in N 2 and H 2 O at a temperature of 500 - 700 °C for 1 hour. In this case, iron was added to the zeolite to obtain FER having 3.0 wt% iron based on the total weight of the zeolite.

[0074] A portion of each iron FER zeolite sample was hydrothermally aged at 650 °C for 50 hours in air containing 10 vol% H 2 O.

[0075] The pelleted fresh and aged samples of iron FER zeolite were placed in a test apparatus. To evaluate the SCR performance of the zeolite over a certain temperature range, the zeolite was exposed to a simulated diesel engine exhaust gas stream having the following characteristics: 525 ppm NH 3 , 500 ppm NO, 12% O 2 , 5% H 2 O, 200 ppm CO, and 4.2% CO 2 , SV = 60 K h -1 . The samples were exposed to the above gas mixture at 150 °C, and the NOx conversion rate and N 2 O selectivity were measured at various steady-state temperatures from 150 to 450 °C.

[0076] As shown in both Figure 4 and Figure 5, the fresh iron FER from Example 2 and 7 had significantly higher NO in the temperature range of 250 - 300 °C compared to the two Comparative Examples 2 and 3 having similar SAR. xThe conversion rate was achieved. The higher NOx conversion rate in the temperature range of 250 to 350 °C for the two FER samples from Examples 2 and 7 was also achieved after the samples were hydrothermally aged.

[0077] Example 3 - Solid NMR Solid NMR was acquired on a Bruker Advance Neo console at a static magnetic field strength of 14.1 T (ν 0 ( 1 H) = 600 MHz) using TopSpin 4.0 software. Before measurement, the zeolite sample was stored overnight in a humid environment. The powder sample was filled into a zirconia MAS rotor equipped with a Kel-F cap. The rotor was rotated using purified compressed air at room temperature. The rotation frequency was 14 kHz and the recycle delay was 0.4 s. The spectra were quantified by integrating over the range of 80 ppm to -30 ppm covering all the observed isotropic peaks and the range of 15 ppm to -30 ppm covering only 6-coordinated AlO 6 The spectrum was quantified by integrating over the range of 80 ppm to -30 ppm covering all the observed isotropic peaks and the range of 15 ppm to -30 ppm covering only 6-coordinated AlO.

Claims

1. Ferrielite (FER) zeolite with the following characteristics: a) SARs 11-20, b) 320-380m ２ BET surface area per g, and c) 0.1-0.2cm ３ Micropore volume per gram.

2. The FER zeolite according to claim 1, wherein the SAR is 11 to 18, preferably 12 to 17.

3. The BET surface area is 347 to 355 m². ２ / g, preferably 348-352m ２ FER zeolite according to claim 1 or claim 2, wherein the amount is / g.

4. The aforementioned micropore volume is 0.12 cm ３ FER zeolite according to claim 1 or claim 2, wherein the amount is / g.

5. The FER zeolite according to claim 1 or claim 2, wherein the zeolite has a crystallinity of more than 95%.

6. The FER zeolite according to claim 1 or claim 2, wherein the zeolite has a crystal size of 1 micrometer or less, preferably 0.9 micrometers or less.

7. The FER zeolite according to claim 1 or claim 2, wherein the 6-coordinate Al content is 15% or less.

8. External surface area is 20 m ２ The FER zeolite according to claim 1 or claim 2, wherein the amount is less than or equal to / g.

9. A method for producing ferrielite (FER) zeolite that does not include an organic template, wherein the method is: (i) Forming a reaction gel containing an aluminum source, sodium hydroxide and / or potassium hydroxide, and silica sol, (ii) Heating the reaction gel to a temperature suitable for the growth of the FER zeolite for a period of time suitable for the growth of the FER zeolite, Includes, A method wherein the reaction gel does not contain seed crystals, and furthermore, the reaction gel does not contain organic structure directing agents (OSDAs).

10. The method according to claim 9, wherein the temperature in step (ii) is 100°C to 200°C, preferably 110°C to 190°C.

11. The method according to claim 9 or claim 10, wherein the period of step (ii) is at least 20 hours, preferably 1 to 6 days.

12. The reaction gel composition has a K ２ O / (K ２ O + Na ２ O) ratio of less than 0.1, according to the method of claim 9 or claim 10

13. A method for producing the FER zeolite described in claim 1 or claim 2, as described in claim 9 or claim 10.

14. A catalyst article for treating exhaust gas, comprising a FER zeolite as described in claim 1 or claim 2, or a FER zeolite that can be obtained by the method described in claim 9 or claim 10.

15. The catalyst article according to claim 14, wherein the FER zeolite is disposed on and / or within the substrate.

16. A method for treating exhaust gas, comprising contacting the exhaust gas with the catalyst article described in claim 14.

17. NO ｘ and / or NH ３ Combustion exhaust gas containing NO is brought into contact with the catalyst article. ｘ At least a portion of N ２ and H ２ Selective reduction to O and / or NH ３ A method for treating exhaust gas according to claim 16, comprising oxidizing at least a portion thereof.

18. A system for treating exhaust gas containing NOx, comprising a catalyst article and a reducing agent source according to claim 14, wherein the reducing agent source is located upstream of the catalyst article.

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