JP2014148441A - Afx type silico-alumino-phosphate and method for producing the same as well as nitrogen oxide reduction method using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a silico-alumino-phosphate of an AFX structure that is used under a moisture containing environment and further that exhibits a high catalytic activity as a nitrogen oxide reduction catalyst.SOLUTION: Provided is a silico-alumino-phosphate of an AFX structure that has a solid acid amount of 0.90 mmol/g or more and contains copper. The silico-alumino-phosphate of the AFX structure containing copper can be obtained by a production method characterized in that it has a mixing step of mixing the silico-alumino-phosphate of the AFX structure and copper containing alcohol.

Description

  The present invention relates to an AFX-structured silicoaluminophosphate containing copper and a method for producing the same. More specifically, the present invention relates to an AFX-structured silicoaluminophosphate containing copper and having a high solid acid amount, a production method thereof, and a nitrogen oxide reduction method using the same.

  The AFX structure is a structure defined in the structure code of the International Zeolite Association (hereinafter referred to as “IZA”). This structure is a structure having eight-membered three-dimensional pores, and the diameter of the pores included in the AFX structure is 0.34 nm × 0.36 nm. As silicoaluminophosphate having an AFX structure, SAPO-56 (Non-patent Documents 1 and 2) and those containing Mn or Zr have been reported (Non-patent Document 1). It has been reported that these SAPO-56 can be used as a catalyst for producing olefins from methanol or an oxidation catalyst for alkanes (Non-patent Document 1).

Studies in Surface Science and Catalysis, 2001, 135, 248 Microporous and Mesoporous Materials, 28 (1999) 125-137

  SAPO-56 disclosed in Non-Patent Documents 1 and 2 is used as a catalyst used in a non-aqueous atmosphere such as an olefin production catalyst. On the other hand, silicoaluminophosphate having an AFX structure has particularly low water resistance among silicoaluminophosphates, and its crystal structure is easily destroyed when used in an aqueous solvent or in a water-containing atmosphere. Similarly, SAPO-56 disclosed in Non-Patent Document 1 has low water resistance, and could not be applied as a catalyst or the like used in a moisture-containing environment.

  An object of the present invention is to solve these problems and to provide a silicoaluminophosphate having an AFX structure that exhibits high catalytic activity as a catalyst that can be used in a moisture-containing environment, and further as a nitrogen oxide reduction catalyst. .

  In view of the above problems, the present inventors diligently studied. As a result, the present inventors have found that silicoaluminophosphate having an AFX structure containing copper can be used as a nitrogen oxide reduction catalyst, and has completed the present invention.

  Hereinafter, the AFX-structured silicoaluminophosphate containing copper of the present invention (hereinafter referred to as “copper-containing AFX-type silicoaluminophosphate”) will be described.

  Silicoaluminophosphate is a zeolite-related substance having silicon (Si), aluminum (Al), phosphorus (P) and oxygen (O) as the main components of its skeleton.

  The composition of silicoaluminophosphate can be generally expressed by the following formula (1).

_{(Si x Al y P z)} O 2 (1)
(However, x + y + z = 1)

  The copper-containing AFX-type silicoaluminophosphate of the present invention is an AFX-structured silicoaluminophosphate (hereinafter referred to as “AFX-type silicoaluminophosphate”). The AFX structure is an AFX type structure when expressed in the IUPAC structure code defined by the IZA Structure Commission.

  The AFX structure can be confirmed by “ATLAS OF ZEOLITE FRAMEWORK TYPES” (2007, page 40, Elsevier). The structure has eight-membered ring three-dimensional pores, and the pore diameter is 0.34 nm × 0.36 nm.

  The copper-containing AFX-type silicoaluminophosphate of the present invention is a crystalline silicoaluminophosphate having an AFX structure. Therefore, in powder X-ray diffraction (hereinafter referred to as “XRD”) measurement, the crystal structure can be identified with the XRD pattern shown in Table 1 below.

  SAPO-56 can be exemplified as the AFX type silicoaluminophosphate.

  The copper-containing AFX type silicoaluminophosphate of the present invention contains copper (Cu). When copper is used as a nitrogen oxide reduction catalyst, it becomes a catalyst having a high nitrogen oxide reduction rate. In the present invention, the copper contained in the copper-containing AFX-type silicoaluminophosphate includes not only the metal but also copper in the form of ions and salts.

  The copper-containing AFX-type silicoaluminophosphate of the present invention preferably has a copper content of 0.5% by weight or more, more preferably 0.8% by weight or more, and 1.2% by weight or more. More preferably. When the copper content is 0.5% by weight or more, the nitrogen oxide reduction rate tends to be higher. On the other hand, if the copper content is too high, side reactions such as reaction between copper and silicoaluminophosphate may occur. Therefore, it can be mentioned that the copper content is 5% by weight or less, further 2% by weight or less, and further 1.8% by weight or less.

  Here, in this invention, content (weight%) of copper is the weight of copper with respect to the dry weight of a copper containing silicoaluminophosphate. The dry weight is the sum of the oxide weights of silicon, phosphorus, aluminum and copper contained in the copper-containing silicoaluminophosphate. The dry weight can be determined, for example, by measuring the weight of the copper-containing silicoaluminophosphate after firing at 600 ° C. for 30 minutes in an air atmosphere.

  The copper contained in the copper-containing AFX-type silicoaluminophosphate of the present invention is preferably uniformly dispersed in the structure and pores of the AFX-type silicoaluminophosphate. Thereby, it becomes easy for the copper-containing AFX type silicoaluminophosphate of the present invention to exhibit a higher nitrogen oxide reduction rate. As a uniform copper dispersion state, it can be illustrated that copper is distributed inside the pores of the AFX type silicoaluminophosphate and on the surface of the AFX type silicoaluminophosphate.

  The copper-containing AFX-type silicoaluminophosphate of the present invention has a solid acid amount of 0.90 mmol / g or more, preferably 0.95 mmol / g or more, and more preferably 1.00 mmol / g or more. preferable. If the amount of solid acid is less than 0.90 mmol / g, the amount of solid acid is too small. When the solid acid amount is 0.90 mmol / g or more, the copper-containing AFX-type silicoaluminophosphate of the present invention becomes a nitrogen oxide reduction catalyst having a high nitrogen oxide reduction rate.

  A higher solid acid amount is preferable, but the upper limit thereof is 1.60 mmol / g or less, further 1.40 mmol / g or less, further 1.35 mmol / g or less, or even 1.30 mmol / g or less, Furthermore, 1.20 mmol / g or less, and further 1.10 mmol / g or less can be mentioned.

  Here, the “solid acid” is an index for evaluating the catalytic activity of silicoaluminophosphate.

  The solid acid can be confirmed and quantified by the ammonia TPD method.

  As the ammonia TPD method, a method having the following three steps can be exemplified.

1) Pretreatment process to remove gas and moisture adsorbed on silicoaluminophosphate 2) Ammonia adsorption process to adsorb ammonia on silicoaluminophosphate, and 3) Ammonia adsorbed on silicoaluminophosphate , Ammonia desorption step to desorb from it.

  The amount of solid acid quantified by the ammonia TPD method is likely to vary depending on the conditions applied in the steps 1) to 3), such as temperature, gas type, gas flow rate, and the like. Examples of the ammonia TPD method in the present invention include the following methods.

  As a pretreatment step, helium gas is circulated at 60 mL / min at 500 ° C. for 1 hour with respect to 0.1 g of the sample. Next, as an ammonia adsorption step, helium gas containing 10% by volume of ammonia is passed through the sample at 60 mL / min at room temperature until the ammonia adsorption to the sample is saturated. Helium gas was circulated through the reaction tube at 60 mL / min, 100 ° C. for 1 hour, and ammonia in the atmosphere was discharged out of the system. I do.

  In the ammonia desorption curve obtained in the ammonia desorption step, the ammonia desorption amount is determined from the area of an ammonia desorption peak (hereinafter referred to as “H-peak”) having an apex at 300 ° C. or higher. The value obtained by dividing the obtained ammonia desorption amount by the sample weight is defined as the solid acid amount (mmol / g) of the silicoaluminophosphate. When there are a plurality of H-peaks, the ammonia desorption amount is determined from the total area of these H-peaks. The weight of the sample at this time is a weight not including moisture physically adsorbed on the sample, that is, a sum of oxide weights of silicon, phosphorus and aluminum contained in the silicoaluminophosphate. As such weight, for example, the weight after heat-treating the sample at 600 ° C. for 30 minutes in an air atmosphere can be used.

  In addition, when there is a minimum value between an ammonia desorption peak (hereinafter referred to as “L-peak”) having an apex in the range of 100 ° C. or more and less than 300 ° C. and the H-peak, it corresponds to the minimum value. The area occupied by the ammonia desorption curve above the temperature to be used is defined as the H-peak area. On the other hand, when there is no minimum value between the L peak and the H-peak, the area occupied by the ammonia desorption curve at 300 ° C. or higher is defined as the H-peak area. When there are a plurality of ammonia desorption peaks, the extreme value between the highest L-peak and the lowest H-peak is taken as the local minimum between the L-peak and the H-peak.

  Next, the manufacturing method of the copper containing AFX type silicoaluminophosphate of this invention is demonstrated.

  The copper-containing AFX-type silicoaluminophosphate of the present invention can be produced by a production method comprising a mixing step of mixing a silicoaluminophosphate having an AFX structure and a copper-containing alcohol.

  In the mixing step, the AFX type silicoaluminophosphate and the copper-containing alcohol are mixed. Thereby, it is possible to obtain a silicoaluminophosphate having a high solid acid amount and containing copper and having an AFX structure (copper-containing AFX-type silicoaluminophosphate).

  In the mixing step, any silicoaluminophosphate can be used as long as it is an AFX-type silicoaluminophosphate. The greater the solid acid amount of the AFX type silicoaluminophosphate used in the mixing step, the greater the solid acid amount of the resulting copper-containing AFX type silicoaluminophosphate. Therefore, the AFX type silicoaluminophosphate used in the mixing step preferably has a solid acid amount of 0.90 mmol / g or more, more preferably 1.3 mmol / g or more, and 1.5 mmol / More preferably, it is g or more.

  The AFX type silicoaluminophosphate used in the mixing step may be produced, for example, by crystallizing a reaction mixture having the following molar composition ratio.

P ₂ O ₅ / Al ₂ O ₃ 0.5 or more, 1.5 or less SiO ₂ / Al ₂ O ₃ 0.2 or more, 1.0 or less H ₂ O / Al ₂ O ₃ 5 or more, 100 or less Oriented to organic structure Agent / Al ₂ O ₃ 0.5 or more and 5 or less

  Examples of the organic structure directing agent include N, N, N ′, N′-tetramethyl-1,6-hexadiamine (hereinafter referred to as “TMHD”).

  Examples of the crystallization conditions include holding the reaction mixture in a sealed pressure vessel at a crystallization temperature of 100 ° C. or more and 250 ° C. or less, a crystallization time of 5 hours or more and 240 hours or less.

  Further, the AFX-type silicoaluminophosphate after crystallization may be appropriately washed and fired for removing impurities and organic structure directing agent.

  The copper-containing alcohol in the mixing step is preferably an alcohol in which a copper salt is dissolved. By adding copper to the AFX-type silicoaluminophosphate using alcohol, the solid acid amount of the obtained copper-containing AFX-type silicoaluminophosphate tends to be high.

  The alcohol is preferably at least one selected from the group of methanol, ethanol, propanol and butanol, more preferably one or more of methanol or ethanol, still more preferably ethanol. Even more preferably, only ethanol is used.

  The concentration of the alcohol is preferably 99% or more, more preferably 99.5% or more. If the alcohol concentration is low, impurities, particularly moisture, are likely to be contained. When alcohol containing water is used, the amount of solid acid of the obtained copper-containing AFX zeolite tends to decrease.

  The water content of the copper-containing alcohol is preferably as small as possible, but it may contain unavoidable water such as water derived from a hydrate contained in the copper salt. Therefore, the water content of the copper-containing alcohol is preferably 5% or less, and more preferably 4% or less. Examples of the alcohol having an alcohol concentration of 99% or more include alcohols treated with a dehydrating agent such as zeolite, and anhydrous alcohols. Of these, alcohol treated with a dehydrating agent is industrially easy to use.

  Any copper salt can be used as long as it is a copper salt that dissolves in alcohol. Examples of the copper salt include copper inorganic acid salts such as copper sulfate, copper nitrate, copper chloride, and copper acetate.

  The copper concentration of the copper-containing alcohol can be appropriately set according to the copper content of the target copper-containing AFX-type silicoaluminophosphate. Examples of the copper concentration of the copper-containing alcohol include, for example, a copper concentration such that the total amount of copper contained in the copper-containing alcohol used for mixing becomes the copper content of the target copper-containing AFX type silicoaluminophosphate. Can do.

  In the mixing step, the amount of the copper-containing alcohol used for mixing is arbitrary. Examples of the amount of the copper-containing alcohol include 10% by weight or more and 100% by weight or less, and further 20% by weight or more and 50% by weight with respect to the weight of the AFX type silicoaluminophosphate used for mixing. The weight of the AFX type silicoaluminophosphate used for mixing is the sum of the weights of oxides of silicon, phosphorus and aluminum contained therein, and does not include the weight of moisture.

  In the production method of the present invention, copper is contained in the AFX type silicoaluminophosphate using the copper-containing alcohol in the mixing step. As one of the reasons why copper is contained while having a high solid acid amount by this method, the following can be considered.

  That is, general copper content is performed using an aqueous solution. In the containing method using an aqueous solution, some side reaction occurs between water and the silicoaluminophosphate, thereby reducing the crystallinity of the silicoaluminophosphate. Therefore, the amount of solid acid of silicoaluminophosphate is reduced in the mixing step. On the other hand, since such a side reaction does not occur in the alcohol, it is considered that the solid acid amount does not decrease even in the mixing step.

  In the manufacturing method of this invention, it is preferable to have a baking process. AFX-type silicoaluminophosphate has an 8-membered ring structure, and its pore diameter is smaller than that of a 10-membered ring structure. By firing the copper-containing AFX-type silicoaluminophosphate after the mixing step, the movement and diffusion of copper into the pores of the AFX-type silicoaluminophosphate is further promoted, and the copper is more stable. It is contained in the AFX type silicoaluminophosphate in a state. In addition, unnecessary components and the like of the copper salt are removed, and copper can be further stabilized.

  The firing temperature in the firing step is 500 ° C. or higher, preferably 550 ° C. or higher, more preferably 600 ° C. or higher, and still more preferably 700 ° C. or higher. By baking at 500 ° C. or higher, copper is further diffused and stabilized in the copper-containing AFX-type silicoaluminophosphate. On the other hand, if the firing temperature is too high, the crystallinity of the copper-containing AFX-type silicoaluminophosphate tends to decrease. Therefore, the firing temperature is preferably less than 900 ° C.

  The firing time can be 30 minutes or more and 10 hours or less. As a result, in the copper-containing AFX-type silicoaluminophosphate, copper easily diffuses and is likely to be stable. The firing time is preferably 1 hour or more and 5 hours or less in order not to lower the crystallinity of the copper-containing AFX type silicoaluminophosphate and to uniformly diffuse copper, but 1 hour or more and 3 hours or less. It is more preferable that

  The copper-containing AFX-type silicoaluminophosphate of the present invention can be used as a nitrogen oxide reduction catalyst by bringing it into contact with a gas containing nitrogen oxides. It can be a reduction method.

  Furthermore, the copper-containing AFX-type silicoaluminophosphate of the present invention is a selective nitrogen oxide reduction that selectively reduces nitrogen oxides by contacting with a gas containing nitrogen oxides and a reducing agent. It can be used as a catalyst, a so-called SCR catalyst, and can be a selective reduction method of nitrogen oxides using this catalyst.

  When the copper-containing AFX type silicoaluminophosphate of the present invention is used as these catalysts, it is used as it is, in a state where it is molded using a binder, or in a state where it is coated on a carrier such as a honeycomb. be able to.

  Examples of the nitrogen oxides include at least one selected from the group consisting of nitric oxide, nitrogen dioxide, dinitrogen trioxide, dinitrogen tetroxide, and dinitrogen monoxide, and furthermore, nitric oxide, There may be mentioned at least one selected from the group of nitrogen and dinitrogen monoxide, and further any one or more of nitrogen monoxide and nitrogen dioxide.

  Examples of the gas containing nitrogen oxide (hereinafter referred to as “nitrogen oxide-containing gas”) include exhaust gas from diesel vehicles, gasoline vehicles, boilers, gas turbines, and the like. The nitrogen oxide-containing gas may contain components other than nitrogen oxide. Examples of components contained other than nitrogen oxides include at least one selected from the group of hydrocarbons, carbon monoxide, carbon dioxide, hydrogen, nitrogen, oxygen, sulfur oxides, and water.

In the nitrogen oxide reduction method using the copper-containing AFX type silicoaluminophosphate of the present invention, the copper-containing AFX type silicoaluminophosphate of the present invention and the nitrogen oxide-containing gas are contacted at an arbitrary space velocity. Just do it. Examples of the contact space velocity include 500 to 500,000 hr ⁻¹ , and 2,000 to 300,000 hr ⁻¹ on a volume basis.

  When the copper-containing AFX-type silicoaluminophosphate of the present invention is used as an SCR catalyst, the reducing agent can include at least one selected from the group consisting of ammonia, urea, and organic amines.

  The method of mixing the reducing agent during the reduction of the nitrogen oxides is arbitrary. For example, the method of mixing the reducing agent as a gas, the method of vaporizing and mixing the aqueous solution, and the method of mixing the reducing agent by spray pyrolysis And so on.

  The present invention can provide a silicoaluminophosphate having an AFX structure exhibiting high catalytic activity as a catalyst used in a moisture-containing environment, and further as a nitrogen oxide reduction catalyst. Furthermore, the present invention can provide a silicoaluminophosphate having an AFX structure suitable for a nitrogen oxide reduction catalyst and containing copper and having a high solid acid content.

  The copper-containing AFX-type silicoaluminophosphate of the present invention can provide a nitrogen oxide reduction catalyst exhibiting a high nitrogen oxide reduction rate in a wide temperature range from a low temperature of 150 ° C. to a high temperature of 500 ° C.

  EXAMPLES Next, although an Example demonstrates this invention further more concretely, this invention is not limited at all by these Examples.

(Powder X-ray diffraction measurement)
Using a general X-ray diffractometer (trade name: MXP-3, manufactured by Mac Science), powder X-ray diffraction measurement of the sample was performed. A CuKα ray (λ = 1.5405 mm) is used as the radiation source, the measurement mode is step scan, the scan condition is 0.04 ° per second, the measurement time is 3 seconds, and the measurement range is 2 ° to 4 ° to 44 °. Measured with

  The sample was identified by comparing the obtained XRD pattern with the powder X-ray diffraction pattern of Table 1.

(Analysis of composition, measurement of copper content)
The composition analysis was performed by inductively coupled plasma emission spectrometry (ICP method). That is, the sample was dissolved in a mixed solution of hydrofluoric acid and nitric acid to prepare a measurement solution. The composition of the sample was analyzed by measuring the obtained measurement solution using a general inductively coupled plasma optical emission analyzer (trade name: OPTIMA 3000 DV, manufactured by PERKIN ELMER), and the copper content was measured.

(Measurement of solid acid content by ammonia TPD method)
0.1 g of a sample was charged into a fixed bed normal pressure flow type reaction tube. The filled sample was pretreated at 500 ° C. for 1 hour under a helium flow of 60 mL / min. Thereafter, helium gas containing 10% by volume of ammonia was circulated at room temperature at 60 mL / min, so that ammonia was saturatedly adsorbed on the sample. After saturation adsorption, ammonia was deaerated by flowing helium through the sample at 100 ° C. for 1 hour at 60 mL / min. After ammonia deaeration, the temperature was raised to 700 ° C. at a rate of 10 ° C./min, and ammonia desorbed from the sample was detected by a thermal conductivity detector. The value obtained by dividing the ammonia desorption amount corresponding to the desorption peak having an apex at 300 ° C. or higher in the desorption curve of ammonia by the weight of the sample after heat treatment at 600 ° C. for 30 minutes in an air atmosphere (unit: mmol / g) was defined as the amount of solid acid.

(Nitrogen oxide reduction test)
The sample was pressed and then crushed and sized to 12 to 20 mesh. 1.5 mL of the sized sample powder was filled into an atmospheric pressure fixed bed flow type reaction tube, and this was used as a catalyst layer. A steady nitrogen oxide reduction test at any one of 150 ° C., 200 ° C., 300 ° C., 400 ° C. and 500 ° C. is conducted while flowing nitrogen gas containing the following components through the catalyst layer at 1500 mL / min. went.

NO: 200ppm
NH ₃ : 200 ppm
O ₂ : 10% by volume
H ₂ O: 3% by volume
N ₂ : remainder

  Using the obtained test results, the nitrogen oxide reduction rate of the sample was determined from the following equation.

_XNOx = {([NOx] _in- [NOx] _out ) / [NOx] _in } * 100

Here, X _NOx is the nitrogen oxide reduction rate (%), [NOx] _in is the nitrogen oxide concentration of the incoming gas, and [NOx] _out is the nitrogen oxide concentration of the outgoing gas after passing through the catalyst layer.

Synthesis example 1
Water 101.5 g, 85% phosphoric acid aqueous solution (special grade, manufactured by Kishida Chemical) 46.5 g, 30% colloidal silica (Nissan Chemical) 8.4 g, TMHD (Tokyo Chemical Industry) 74.4 g, 77% pseudo boehmite ( (Pural SB, manufactured by Sasol) (19.1 g) was mixed to obtain a reaction mixture having the following molar composition.

P ₂ O ₅ / Al ₂ O ₃ = 1.4
SiO ₂ / Al ₂ O ₃ = 0.3
H ₂ O / Al ₂ O ₃ = 50
TMHD / Al ₂ O ₃ = 3.0

  This reaction mixture was put into a 200 mL stainless steel sealed pressure vessel and crystallized by maintaining at 200 ° C. for 69 hours under rotation.

  The product after crystallization was filtered, washed with water, and dried overnight at 110 ° C. to dry the product. The product after drying had an AFX structure as a crystal structure and had the following composition.

(Si _0.09 Al _0.50 P _0.41 ) O ₂

  This confirmed that the product was an AFX-type silicoaluminophosphate.

  The obtained AFX type silicoaluminophosphate was baked at 600 ° C. for 2 hours to obtain the AFX type silicoaluminophosphate of Synthesis Example 1. The solid acid amount of the AFX type silicoaluminophosphate was 1.08 mmol / g.

Synthesis example 2
112.6 g of water, 34.4 g of 85% phosphoric acid aqueous solution, 5.8 g of 30% colloidal silica, 77.2 g of TMHD, and 19.9 g of 77% pseudoboehmite were mixed to prepare a reaction mixture having the following molar composition.

P ₂ O ₅ / Al ₂ O ₃ = 1.0
SiO ₂ / Al ₂ O ₃ = 0.2
H ₂ O / Al ₂ O ₃ = 50
TMHD / Al ₂ O ₃ = 3.0

  This reaction mixture was put into a 200 mL stainless steel sealed pressure vessel and crystallized by maintaining at 200 ° C. for 71 hours under rotation.

  The product after crystallization was filtered, washed with water, and dried overnight at 110 ° C. to dry the product. The product after drying had an AFX structure as a crystal structure and had the following composition.

(Si _0.11 Al _0.50 P _0.39 ) O ₂

  This confirmed that the product was an AFX-type silicoaluminophosphate.

  The obtained AFX type silicoaluminophosphate was calcined at 600 ° C. for 2 hours to obtain the AFX type silicoaluminophosphate of Synthesis Example 4. The solid acid amount of the AFX type silicoaluminophosphate was 1.30 mmol / g.

Example 1
Ethanol (first grade reagent, manufactured by Nippon Alcohol Sangyo Co., Ltd.) was contacted with 3A zeolite compact (Zeolam A-3, manufactured by Tosoh Corporation) overnight, and this was dehydrated. In 3.6 g of ethanol after dehydration treatment, 0.65 g of copper nitrate trihydrate (special grade reagent, manufactured by Kishida Chemical Co., Ltd.) was dissolved to obtain copper nitrate-containing dehydrated ethanol.

  10 g of AFX type silicoaluminophosphate of Synthesis Example 1 and copper nitrate-containing dehydrated ethanol were mixed in a mortar for 5 minutes to obtain a mixture, which was dried at 110 ° C. for 30 minutes. The dried mixture was baked in an air atmosphere at 800 ° C. for 1 hour to obtain a copper-containing AFX-type silicoaluminophosphate of this example.

  The copper-containing AFX-type silicoaluminophosphate had a crystal structure of AFX structure, a copper content of 1.6% by weight, and a solid acid amount of 0.98 mmol / g.

Example 2
Ethanol was dehydrated in the same manner as in Example 1. Copper nitrate trihydrate 0.62 g was dissolved in 3.6 g of ethanol after the dehydration treatment to obtain copper nitrate-containing dehydrated ethanol.

  By mixing, drying, and firing the AFX type silicoaluminophosphate 10 g of Synthesis Example 2 and the copper nitrate-containing dehydrated ethanol in the same manner as in Example 1, the copper-containing AFX type silicoaluminum of this Example was obtained. Norolinate was obtained.

  The copper-containing AFX-type silicoaluminophosphate had an AFX structure as a crystal structure, a copper content of 1.4% by weight, and a solid acid amount of 1.17 mmol / g.

Comparative Example 1
This comparative example was the same as Example 1 except that an aqueous copper nitrate solution in which 0.65 g of copper nitrate trihydrate was dissolved in 3.6 g of pure water was used instead of dehydrated ethanol containing copper nitrate. Of copper-containing silicoaluminophosphate was obtained.

  The copper-containing silicoaluminophosphate was remarkably reduced in crystallinity and amorphous, and did not have an AFX structure. The copper-containing silicoaluminophosphate had a copper content of 1.6% by weight and a solid acid amount of 0.07 mmol / g.

Comparative Example 2
This comparative example was the same as Example 2 except that a copper nitrate aqueous solution in which 0.65 g of copper nitrate trihydrate was dissolved in 3.6 g of pure water was used instead of copper nitrate-containing dehydrated ethanol. Of copper-containing silicoaluminophosphate was obtained.

  The copper-containing silicoaluminophosphate was remarkably reduced in crystallinity and amorphous, and did not have an AFX structure. The copper-containing silicoaluminophosphate had a copper content of 1.6% by weight and a solid acid amount of 0.07 mmol / g.

Measurement example (nitrogen oxide reduction test)
The copper-containing AFX-type silicoaluminophosphate obtained in Examples 1 and 2 and Comparative Example 1 was subjected to a nitrogen oxide reduction test.

  In addition, the test is a sample after synthesis, that is, a copper-containing AFX-type silicoaluminophosphate in a state (hereinafter referred to as “before endurance treatment”) which is baked at 800 ° C. in an air atmosphere after containing copper, The copper-containing AFX type silicoaluminophosphate was subjected to a durability treatment under the following conditions (hereinafter referred to as “after durability treatment”).

  Table 2 shows the nitrogen oxide reduction rates of the samples before and after the durability treatment.

(Durable treatment)
The copper-containing AFX-type silicoaluminophosphate before endurance treatment was press-molded and then sized to 12 to 20 mesh. After the sizing, 3 mL of copper-containing AFX-type silicoaluminophosphate was filled in an atmospheric pressure fixed bed flow-type reaction tube, and air containing 10% by volume of H ₂ O was circulated at 300 mL / min. did. Air circulation was performed at 900 ° C. for 1 hour.

  From Table 2, the sample obtained in the Example showed a high nitrogen oxide reduction rate from 150 ° C. to 500 ° C. in any state before and after the durability treatment. Particularly in all regions from 150 ° C. to 500 ° C., the nitrogen oxide reduction rate after the durability treatment exceeded the nitrogen oxide reduction rate before the durability treatment. This suggested that the endurance treatment further promoted the metal dispersion stabilization in the AFX type silicoaluminophosphate. Further, it was found that a high nitrogen oxide reduction rate was exhibited even in a relatively low temperature region of 40% or higher at 150 ° C. and 60% or higher at 200 ° C.

  On the other hand, the sample obtained in Comparative Example 1 had a lower nitrogen oxide reduction rate than the sample obtained in the Example both before and after the durability treatment. In particular, at a low temperature of 200 ° C. or less, it was found that the nitrogen oxide reduction rate was 6% or less even before the endurance treatment, and the nitrogen oxide could hardly be reduced.

  The copper-containing AFX-type silicoaluminophosphate of the present invention can be used as a catalyst, particularly a nitrogen oxide reduction catalyst or an SCR catalyst.

Claims (8)

  A silicoaluminophosphate having an AFX structure having a solid acid amount of 0.90 mmol / g or more and containing copper.   The silicoaluminophosphate according to claim 1, wherein the copper content is 0.5 wt% or more.   The method for producing a silicoaluminophosphate according to claim 1 or 2, further comprising a mixing step of mixing a silicoaluminophosphate having an AFX structure and a copper-containing alcohol.   In the said mixing process, alcohol is ethanol, The manufacturing method of the silicoaluminophosphate of Claim 3 characterized by the above-mentioned.   The method for producing a silicoaluminophosphate according to claim 3 or 4, further comprising a baking step after the mixing step.   The method for producing a silicoaluminophosphate according to claim 5, wherein in the firing step, a firing temperature is 500 ° C. or more.   A method for producing a nitrogen oxide reduction catalyst, wherein the silicoaluminophosphate according to claim 1 or 2 is used.   A method for reducing a nitrogen oxide, wherein the silicoaluminophosphate according to claim 1 or 2 is used.