GIS-type zeolite, molded body, adsorbent, separation method, method for producing purified carbon dioxide, method for producing purified gas, and separation apparatus.

Abstract

The present invention provides a GIS-type zeolite with reduced adsorption / desorption hysteresis, a molded body, an adsorbent, a separation method, a method for producing purified carbon dioxide, a method for producing purified gas, and a separation apparatus. [Solution] A GIS-type zeolite having an acid content of 0.01 mmol / g or more per gram of zeolite at 300-500°C, as measured by a temperature-induced desorption method; a separation method using the GIS-type zeolite; and a separation apparatus using the GIS-type zeolite.

Description

Technical Field

[0001] The present invention relates to a GIS-type zeolite, a molded body, an adsorbent, a separation method, a method for producing purified carbon dioxide, a method for producing a purified gas, and a separation apparatus.

Background Art

[0002] Zeolites can be used as adsorbents, desiccants, separation agents, catalysts, catalyst carriers, detergent aids, ion exchangers, wastewater treatment agents, fertilizers, food additives, cosmetic additives, etc., and are particularly useful for gas separation applications.

[0003] Among zeolites, those having a GIS structure in the code that defines the structure of zeolites determined by the IZA (International Zeolite Association) are called GIS-type zeolites. GIS-type zeolites are zeolites having pores composed of 8-membered oxygen rings. Such GIS-type zeolites are described in, for example, Patent Documents 1 and 2.

[0004] As a GIS-type zeolite having less crystal lattice strain and defects, a clearly formed crystal structure, capable of sufficiently adsorbing carbon dioxide (CO2) and having a high selectivity of carbon dioxide adsorption with respect to the adsorption amount of methane (CH4), a GIS-type zeolite having an aluminum atom content of 1% by mass or more and a phosphorus atom content of 4% by mass or less, wherein the carbon dioxide saturation adsorption amount a of the GIS-type zeolite measured when the GIS-type zeolite and carbon dioxide are placed in a system at 25°C and 760 mmHg is 5 cm 3 / g or more at 25°C and 760 mmHg is disclosed.

[0005] Patent Document 2 discloses a GIS-type zeolite that can sufficiently adsorb carbon dioxide (CO2) and has high selectivity for carbon dioxide adsorption relative to the amount of methane (CH4) adsorbed. This GIS-type zeolite has a diffraction peak of (1 0 1) between diffraction angles 2θ = 12.55 to 12.90° in the spectrum obtained by X-ray diffraction. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. WO2018 / 110559 [Patent Document 2] International Publication No. WO2019 / 202933 [Overview of the project] [Problems that the invention aims to solve]

[0007] Focusing on the carbon dioxide adsorption capacity of GIS-type zeolites, it becomes possible to separate, recover, and purify carbon dioxide through adsorption and desorption, for example, and applications are expected from the perspective of contributing to the realization of carbon neutrality. When performing carbon dioxide adsorption and desorption using GIS-type zeolites, methods such as pressure swing adsorption separation, temperature swing adsorption separation, or pressure and temperature swing adsorption separation are used, but it is required that the adsorption and desorption hysteresis of carbon dioxide be reduced in these separation methods. Adsorption and desorption hysteresis refers to the phenomenon in which hysteresis occurs in adsorption and desorption on the carbon dioxide adsorption and desorption isotherm. When the adsorption and desorption hysteresis is large, the amount of adsorbed during adsorption decreases, and consequently, the amount desorbed during regeneration decreases, which has the problem of reducing the efficiency of carbon dioxide.

[0008] Therefore, the object of the present invention is to provide a GIS-type zeolite with reduced adsorption / desorption hysteresis, a molded body, an adsorbent, a separation method, a method for producing purified carbon dioxide, a method for producing purified gas, and a separation apparatus. [Means for solving the problem]

[0009] The present invention encompasses the following embodiments. <1> GIS-type zeolite in which the acid content at 300-500°C per gram of zeolite is 0.01 mmol / g or more, as measured by the temperature-controlled desorption method. <2> In the peaks obtained by X-ray diffraction, the diffraction peaks are located between 2θ = 12.10° and 13.22°. <1> GIS-type zeolite as described above. <3> In the peaks obtained by X-ray diffraction, the diffraction peaks are located between 2θ = 27.55° and 28.74°. <1> or <2> GIS-type zeolite as described above. <4> Regarding the ammonia desorption temperature in NH3-TPD measurement, the position of the peak with maximum intensity in the temperature range above 300°C is P H When denoted as (°C), 370°C ≤ P H Satisfying ≤650℃, <1> ~ <3> GIS-type zeolite as described in any of the following. <5> Regarding the ammonia desorption temperature in NH3-TPD measurement, the position of the peak with maximum intensity in the temperature range below 300°C is P L When (°C), 185°C ≤ P L Satisfying ≤250℃, <1> ~ <4> GIS-type zeolite as described in any of the following. <6> The silica-alumina ratio is 3.40 or higher. <1> ~ <5> GIS-type zeolite as described in any of the following. <7> The zeolite contains potassium as a cation species. <1> ~ <6> GIS-type zeolite as described in any of the following. <8> The ratio of potassium atom concentration to aluminum atom concentration in the zeolite (K / Al) is 0.05 or higher. <7> GIS-type zeolite as described above. <9> The ratio (A / T) of the total amount of potassium and lithium in the zeolite to the total amount of alkali metals (T) is 0.05 or greater. <7> or <8> GIS-type zeolite as described above. <10> <1> ~ <9> A molded body containing a GIS-type zeolite as described in any of the following. <11> <1> ~ <9> An adsorbent containing a GIS-type zeolite as described in any of the following. <12> A method for separating carbon dioxide from a mixed gas containing carbon dioxide and a second component gas other than carbon dioxide, using an adsorbent, An adsorption step is performed by bringing the adsorbent into contact with the mixed gas to adsorb carbon dioxide onto the adsorbent, A desorption step is performed by distributing the adsorbent under reduced pressure to remove the carbon dioxide from the adsorbent. Includes, The adsorbent is <1> ~ <9> A separation method comprising a GIS-type zeolite as described in any of the following. <13> <12> A method for producing purified carbon dioxide, comprising producing purified carbon dioxide by the separation method described herein. <14> <12> A method for producing purified gas, comprising producing a purified second component gas by the separation method described herein. <15> <1> ~ <9> A carbon dioxide adsorption tower filled with an adsorbent containing a GIS-type zeolite as described in any of the above, A mixed gas supply line supplies a mixed gas containing carbon dioxide and a second component gas different from carbon dioxide into the carbon dioxide adsorption tower, A depressurization device for reducing the pressure of the carbon dioxide adsorption tower, A carbon dioxide recovery line that recovers carbon dioxide from carbon dioxide adsorption during depressurization, A separation device having [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a GIS-type zeolite with reduced adsorption-desorption hysteresis, a molded body, an adsorbent, a separation method, a method for producing purified carbon dioxide, a method for producing purified gas, and a separation apparatus. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a diagram illustrating the schematic configuration of the purified gas production apparatus 100 according to this embodiment. [Figure 2] Figure 2 is a conceptual diagram showing the carbon dioxide adsorption tower and the change in pressure fluctuations of the carbon dioxide adsorption tower over time, due to the operation of the purified gas production apparatus 100. [Modes for carrying out the invention]

[0012] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). The present invention is not limited to the following description and can be implemented in various modifications within the scope of its gist.

[0013] In this specification, for example, a numerical range notation such as "1 to 100" includes both its lower limit "1" and upper limit "100". The same applies to other numerical range notations.

[0014] [GIS-type zeolite] The GIS-type zeolite according to this embodiment has an acid content of 0.01 mmol / g or more per gram of zeolite at 300-500°C, as measured by the temperature-controlled desorption method (TPD). This configuration provides a GIS-type zeolite, a molded article, and a separation method with reduced adsorption-desorption hysteresis.

[0015] [Amount of acid] The GIS-type zeolite according to this embodiment has reduced adsorption / desorption hysteresis due to the acid amount being 0.01 mmol / g or more. From the same perspective, the acid amount is preferably 0.05 mmol / g or more, more preferably 0.10 mmol / g to 1.00 mmol / g, and still more preferably 0.20 mmol / g to 0.80 mmol / g.

[0016] The acid amount is the acid amount at 300 to 500 °C per 1 g of zeolite and is a value measured by the temperature-programmed desorption method (TPD). A more specific measurement method is according to the method described in the examples.

[0017] As described later, the acid amount can be made within the above range by washing the GIS-type zeolite with an acid.

[0018] 〔Peak positions P H and P L 〕 For the GIS-type zeolite according to this embodiment, regarding the ammonia desorption temperature in the NH3-TPD measurement, when the position of the peak having the maximum intensity in the temperature range of 300 °C or higher is P H (°C), it preferably satisfies 370 °C ≤ P H ≤ 650 °C. When P H (°C) is within this range, the adsorption / desorption hysteresis can be reduced. The reason for this is not clear, but P H becomes larger as the distance between the ion exchange sites in the ultra-micropores in the zeolite framework is longer. However, when P H is 370 °C or higher, the distance between the ion exchange sites is appropriately maintained, the adsorption / desorption energy decreases, and on the other hand, when P H is 650 °C or lower, the trapdoor effect is suppressed by occupying the central part of the pores, and these factors are considered to contribute to the reduction of the adsorption / desorption hysteresis. For the GIS-type zeolite according to this embodiment, it more preferably satisfies 380 °C ≤ P H ≤ 550 °C, and still more preferably satisfies 400 °C ≤ P H ≤ 500 °C. P within the above rangeH To obtain this result, the strength of the acid used in the acid cleaning operation, the concentration of the acid, the number of treatments, etc., can be controlled.

[0019] In this embodiment, the GIS-type zeolite has a peak position with maximum intensity in the temperature range below 300°C for ammonia desorption temperature in NH3-TPD measurement. L When (°C) is used, preferably 185°C ≤ P L Satisfy ≤250℃. P L The fact that (°C) is within this range reduces the hysteresis of adsorption and desorption. The reason for this is unclear, but P L The value of P increases as the distance between ion exchange sites in the zeolite skeleton increases, L When the temperature is above 185°C, the distance between ion exchange sites is appropriately maintained, the adsorption and desorption energy decreases, and on the other hand, P L The fact that the temperature is below 250°C occupies the center of the pores, suppressing the trapdoor effect, and these factors are thought to contribute to the reduction of adsorption-desorption hysteresis. In this embodiment, the GIS-type zeolite is more preferably 190°C ≤ P from the viewpoint of further enhancing the effect of reducing adsorption-desorption hysteresis. L Satisfying ≤240℃, and more preferably 195℃ ≤P L The temperature must be ≤230℃. P within the aforementioned range L To obtain this result, the strength of the acid used in the acid cleaning operation, the concentration of the acid, the number of treatments, etc., can be controlled.

[0020] Above, the peak position P H and P L The method for measuring the ammonia desorption temperature when determining the ammonia is a temperature-increasing desorption method using ammonia, but more specifically, it is as described in the examples.

[0021] [X-ray diffraction] In this embodiment, the GIS-type zeolite preferably has a diffraction peak between 2θ = 12.10° and 13.22° in the peak obtained by X-ray diffraction. This diffraction peak is attributed to the (1 0 1) plane diffraction peak. The (1 0 1) plane diffraction peak reflects the periodic structure of the 8-membered oxygen ring of the GIS-type zeolite, and using a GIS-type zeolite having a diffraction peak exhibiting this structure tends to further improve the selectivity of carbon dioxide. In this specification, "having a diffraction peak" means that the peak intensity obtained by X-ray diffraction has a value of twice or more the background amplitude.

[0022] In this embodiment, the GIS-type zeolite preferably has a diffraction peak between 2θ = 27.55° and 28.74° in the peak obtained by X-ray diffraction. This diffraction peak is attributed to the (2 1 1) plane diffraction peak. The (2 1 1) plane diffraction peak reflects the fine periodic structure of the 8-membered oxygen ring of the GIS-type zeolite, and using a GIS-type zeolite having a diffraction peak exhibiting this structure tends to further improve the selectivity of carbon dioxide.

[0023] In this embodiment, the GIS-type zeolite preferably has a diffraction peak between 2θ = 17.16° and 18.28°. This diffraction peak is attributed to the (200) plane diffraction peak. The (200) plane diffraction peak reflects the fine periodic structure of the 8-membered oxygen ring of the GIS-type zeolite, and using a GIS-type zeolite having a diffraction peak exhibiting this structure tends to further improve the selectivity of carbon dioxide.

[0024] When the diffraction peak height between 2θ = 12.10° and 13.22° is A, and the diffraction peak height between 2θ = 17.16° and 18.28° is B, the value of A / B is preferably 0.10 or more, more preferably 0.20 or more, and even more preferably 0.30 or more. By setting this ratio, the diffraction peak of the (1 0 1) plane becomes more prominent, and the selectivity of carbon dioxide tends to improve further.

[0025] For the aforementioned X-ray diffraction, for example, a sample of dried GIS-type zeolite, ground in an agate mortar, is used. For X-ray diffraction, the X-ray diffraction spectrum obtained using an X-ray diffractometer (XRD) (Rigaku Corporation's powder X-ray diffractometer "RINT2500" (product name)) is analyzed using XRD data analysis software (Rigaku Corporation's "PDXL2" (product name)), with the "α cut value" setting in the analysis software set to 3.00, and the 2θ value and peak height of the peak are measured.

[0026] [Silica-alumina ratio (SAR)] The silica-alumina ratio (represented as the molar ratio of silica to alumina expressed as SiO2 / Al2O3, hereinafter also simply referred to as "SAR") of the GIS-type zeolite according to this embodiment is preferably 3.40 or higher, more preferably 4.40 to 3000, more preferably 4.50 to 500, even more preferably 4.69 to 100, even more preferably 4.90 to 100, even more preferably 5.40 to 100, and even more preferably 6.01 to 100. The SAR of GIS-type zeolite is 29 SAR is determined by measuring Si-MAS-NMR. More specifically, SAR can be measured by the method described in the examples below. The SAR of GIS-type zeolite can be adjusted by the ratio of water and OH- in the mixed gel during zeolite preparation.

[0027] [Cationic species] From the viewpoint of improving the selective adsorption capacity of carbon dioxide, it is preferable that the GIS-type zeolite contains potassium or lithium as a cation species, and more preferably potassium.

[0028] The total potassium and lithium content in GIS-type zeolite is calculated as the ratio (Z / T) of the total amount of potassium and lithium to the total amount of alkali metals (T) in the GIS-type zeolite. Z / T is preferably 0.05 or higher, more preferably 0.10 or higher, and even more preferably 0.15 or higher. There is no particular upper limit to Z / T, but it may be 1.00 or lower. Z / T can be measured by thermally dissolving the zeolite in an aqueous sodium hydroxide solution or aqua regia and performing ICP-emission spectroscopy on a solution that has been appropriately diluted. More specifically, Z / T can be measured by the method described in the examples below. Z / T can be adjusted by changing the ratio of potassium and lithium cation species in the GIS-type zeolite before the acid treatment described below.

[0029] The ratio (K / T) of the total amount of potassium to the total amount of each alkali metal (T) in the GIS-type zeolite is preferably 0.05 or higher. Having K / T within this range yields a GIS-type zeolite with excellent thermal stability. K / T is more preferably 0.10 or higher, and even more preferably 0.15 or higher. There is no particular upper limit to K / T, but K / T may be 1.00 or lower. Z / T can be adjusted by changing the proportion of potassium cation species in the GIS-type zeolite before acid treatment, as described later.

[0030] [Method for manufacturing GIS-type zeolite] The method for producing GIS-type zeolite according to this embodiment may include, for example, a step of preparing a mixed gel containing a silica source containing silicon, an aluminum source containing aluminum, an alkali source containing at least one selected from alkali metals (M1) and alkaline earth metals (M2), a salt compound containing at least one selected from alkali metals (M1) and alkaline earth metals (M2), a phosphorus source containing phosphorus, an organic structure-determining agent, and water. The mixed gel and each of its components will be described below.

[0031] [Mixed gel] In this embodiment, the mixed gel is a mixture containing a silica source, an aluminum source, a salt compound, and water as components, and optionally containing a phosphorus source, an alkali source, and an organic structure-correcting agent.

[0032] Silica source refers to the component in the mixed gel that serves as the raw material for silicon contained in the zeolite manufactured from the mixed gel; aluminum source refers to the component in the mixed gel that serves as the raw material for aluminum contained in the zeolite manufactured from the mixed gel; salt compound refers to the component that serves as the raw material for alkali metals and / or alkaline earth metals contained in the zeolite manufactured from the mixed gel; alkali source refers to the component that adjusts the alkalinity of the mixed gel; and phosphorus source refers to the component in the mixed gel that serves as the raw material for phosphorus contained in the zeolite manufactured from the mixed gel.

[0033] [Silica source] The silica source is not particularly limited as long as it is commonly used, and examples include crystalline silica, amorphous silica, silicic acid, silicates, and organic silicate compounds. More specific examples include sodium silicate, potassium silicate, calcium silicate, magnesium silicate, fumed silica, precipitated silica, silica gel, colloidal silica, aluminosilicate, tetraethoxysilane (TEOS), and trimethylethoxysilane. These compounds may be used individually or in combination. Here, aluminosilicate serves as both a silica source and an aluminum source.

[0034] Among these, fumed silica, colloidal silica, or precipitated silica are preferred because they tend to yield zeolites with a high degree of crystallinity.

[0035] [Aluminum source] The aluminum source is not particularly limited as long as it is commonly used, but specific examples include sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum hydroxide, aluminum oxide, aluminum chloride, aluminum alkoxide, metallic aluminum, amorphous aluminosilicate gel, etc. These compounds may be used individually or in combination.

[0036] Among these, sodium aluminate, aluminum sulfate, aluminum nitrate, aluminum acetate, aluminum hydroxide, aluminum chloride, and aluminum alkoxide are preferred because they tend to yield zeolites with a high degree of crystallinity. From a similar viewpoint, sodium aluminate and aluminum hydroxide are more preferred, and sodium aluminate is even more preferred.

[0037] [Salt compounds] Salt compounds are compounds containing alkali metals such as Li, Na, K, Rb, and Cs, or alkaline earth metals such as Ca, Mg, Sr, and Ba, which promote crystallization into a zeolite structure when producing zeolites. From the viewpoint of facilitating crystal formation of the GIS-type framework, the alkali metals and alkaline earth metals included in the added salt compound are preferably Na and K, and more preferably Na. Salt compounds may be used individually or in combination.

[0038] Specifically, the salt compounds are not limited to the following, but include, for example, sodium sulfate, sodium sulfite, sodium thiosulfate, sodium nitrite, sodium nitrate, sodium carbonate, sodium bicarbonate, sodium phosphate, sodium acetate, sodium formate, sodium citrate, sodium oxalate, sodium fluoride, sodium chloride, sodium bromide, sodium iodide, sodium thiosodium, sodium silicate, sodium metasilicate, sodium tetraborate, sodium chlorate, sodium perchlorate, sodium cyanide, sodium metastanate, sodium hexahydroxydostan(IV)ate, sodium hexacyanoferrate(II)ate, sodium permanganate, sodium chromate, sodium dichromate, Potassium sulfate, potassium sulfite, potassium thiosulfate, potassium nitrite, potassium nitrate, potassium carbonate, potassium bicarbonate, potassium phosphate, potassium acetate, potassium formate, potassium citrate, potassium oxalate, potassium fluoride, potassium chloride, potassium bromide, potassium iodide, potassium thiopotassium, potassium silicate, potassium metasilicate, potassium tetraborate, potassium chlorate, potassium perchlorate, potassium cyanide, potassium metastanate, potassium hexahydroxydostan(IV)ate, potassium hexacyanoferrate(II)ate, potassium permanganate, potassium chromate, potassium dichromate, Lithium sulfate, lithium sulfite, lithium thiosulfate, lithium nitrite, lithium nitrate, lithium carbonate, lithium bicarbonate, lithium phosphate, lithium acetate, lithium formate, lithium citrate, lithium oxalate, lithium fluoride, lithium chloride, lithium bromide, lithium iodide, thiolithium, lithium silicate, lithium metasilicate, lithium tetraborate, lithium chlorate, lithium perchlorate, lithium cyanide, lithium metastanate, lithium hexahydroxydostan(IV)ate, lithium hexacyanoferrate(II)ate, lithium permanganate, lithium chromate, lithium dichromate, Rubidium sulfate, rubidium sulfite, rubidium thiosulfate, rubidium nitrite, rubidium nitrate, rubidium carbonate, rubidium bicarbonate, rubidium phosphate, rubidium acetate, rubidium formate, rubidium citrate, rubidium oxalate, rubidium fluoride, rubidium chloride, rubidium bromide, rubidium iodide, thiorbidium, rubidium silicate, rubidium metasilicate, rubidium tetraborate, rubidium chlorate, rubidium perchlorate, rubidium cyanide, rubidium metastanate, rubidium hexahydroxydostan(IV)ate, rubidium hexacyanoferrate(II)ate, rubidium permanganate, rubidium chromate, rubidium dichromate, Cesium sulfate, cesium sulfite, cesium thiosulfate, cesium nitrite, cesium nitrate, cesium carbonate, cesium bicarbonate, cesium phosphate, cesium acetate, cesium formate, cesium citrate, cesium oxalate, cesium fluoride, cesium chloride, cesium bromide, cesium iodide, thiocesium, cesium silicate, cesium metasilicate, cesium tetraborate, cesium chlorate, cesium perchlorate, cesium cyanide, cesium metastanate, cesium hexahydroxydostan(IV)ate, cesium hexacyanoferrate(II)ate, cesium permanganate, cesium chromate, cesium dichromate, Magnesium sulfate, magnesium sulfite, magnesium thiosulfate, magnesium nitrite, magnesium nitrate, magnesium carbonate, magnesium bicarbonate, magnesium phosphate, magnesium acetate, magnesium formate, magnesium citrate, magnesium oxalate, magnesium fluoride, magnesium chloride, magnesium bromide, magnesium iodide, thiomagnesium, magnesium silicate, magnesium metasilicate, magnesium tetraborate, magnesium chlorate, magnesium perchlorate, magnesium cyanide, magnesium metastanate, magnesium hexahydroxydostan(IV)ate, magnesium hexacyanoferrate(II)ate, magnesium permanganate, magnesium chromate, magnesium dichromate, Calcium sulfate, calcium sulfite, calcium thiosulfate, calcium nitrite, calcium nitrate, calcium carbonate, calcium bicarbonate, calcium phosphate, calcium acetate, calcium formate, calcium citrate, calcium oxalate, calcium fluoride, calcium chloride, calcium bromide, calcium iodide, calcium thiocalcium, calcium silicate, calcium metasilicate, calcium tetraborate, calcium chlorate, calcium perchlorate, calcium cyanide, calcium metastanate, calcium hexahydroxydostan(IV)ate, calcium hexacyanoferrate(II)ate, calcium permanganate, calcium chromate, calcium dichromate, Strontium sulfate, strontium sulfite, strontium thiosulfate, strontium nitrite, strontium nitrate, strontium carbonate, strontium bicarbonate, strontium phosphate, strontium acetate, strontium formate, strontium citrate, strontium oxalate, strontium fluoride, strontium chloride, strontium bromide, strontium iodide, thiostrontium, strontium silicate, strontium metasilicate, strontium tetraborate, strontium chlorate, strontium perchlorate, strontium cyanide, strontium metastanate, strontium hexahydroxydostan(IV)ate, strontium hexacyanoferrate(II)ate, strontium permanganate, strontium chromate, strontium dichromate, Examples include barium sulfate, barium sulfite, barium thiosulfate, barium nitrite, barium nitrate, barium carbonate, barium bicarbonate, barium phosphate, barium acetate, barium formate, barium citrate, barium oxalate, barium fluoride, barium chloride, barium bromide, barium iodide, thiobarium, barium silicate, barium metasilicate, barium tetraborate, barium chlorate, barium perchlorate, barium cyanide, barium metastanate, barium hexahydroxydostan(IV)ate, barium hexacyanoferrate(II)ate, barium permanganate, barium chromate, barium dichromate, and the like.

[0039] [Alkaline source] The alkali source is used in the production of zeolites to adjust the alkalinity (pH) of the mixed gel in order to promote crystallization into a zeolite structure. The alkali used can be any alkaline compound, and can be either an inorganic or organic compound, but inorganic compounds are preferred from a cost standpoint, and alkali metal hydroxides are more preferred. Examples of alkali metal hydroxides include lithium hydroxide, sodium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide, with sodium hydroxide and potassium hydroxide being preferred, and sodium hydroxide being more preferred. These compounds may be used individually or in combination.

[0040] The phosphorus source is not particularly limited as long as it is commonly used, but specific examples include aqueous phosphoric acid solution, sodium phosphate, aluminum phosphate, potassium phosphate, lithium phosphate, calcium phosphate, and barium phosphate. These compounds may be used individually or in combination.

[0041] Among these, aqueous phosphoric acid solution, sodium phosphate, and aluminum phosphate are preferred because they tend to yield zeolites with a high degree of crystallinity. From a similar viewpoint, aqueous phosphoric acid solution and sodium phosphate are more preferred, and aqueous phosphoric acid solution is even more preferred.

[0042] [Organic structure directing agent] In the production of zeolites by hydrothermal synthesis of mixed gels, the organic structure-determining agent is a compound that promotes crystallization into a zeolite structure. In the crystallization of zeolites, the organic structure-determining agent can be used as needed.

[0043] The organic structure modifier can be of any type, as long as it is capable of forming the desired GIS-type zeolite. Furthermore, the organic structure modifier may be used alone or in combination with other organic structures modifiers.

[0044] Organic structure-determining agents can be used, but are not limited to the following: amines, quaternary ammonium salts, alcohols, ethers, amides, alkylureas, alkylthioureas, cyanoalkanes, and alicyclic heterocyclic compounds containing nitrogen as a heteroatom. Alkylamines are preferred, and isopropylamines are more preferred.

[0045] Some of these salts are accompanied by anions. Representative examples of such anions include, but are not limited to, Cl - , Br - , I - These include halogen ions, hydroxide ions, acetate ions, sulfate ions, nitrate ions, carbonate ions, and bicarbonate ions. Of these, halogen ions and hydroxide ions are preferred, and halogen ions are more preferred, from the viewpoint of facilitating crystal formation of the GIS-type framework.

[0046] [Composition ratio of the mixed gel] In this embodiment, the addition of salt compounds containing alkali metals and / or alkaline earth metals is crucial for synthesizing GIS-type zeolites with an appropriate structure. Zeolite formation involves the reaction and crystallization of silica and aluminum sources dissolved in an aqueous solvent. By adding salt compounds, it is possible to adjust the bonding mode and relative abundance of Si and Al within the zeolite framework, thereby enabling the synthesis of GIS with an ideal crystal structure.

[0047] Furthermore, the ratio of cations to the aluminum source resulting from the addition of salt compounds is particularly important. The ratio of cations to the aluminum source resulting from salt compounds in the mixed gel is expressed as the molar ratio of the amount of cations E to Al2O3, i.e., E / Al2O3. Here, E represents the molar amount of cations resulting from the salt compound; for example, when sodium nitrate is added, the cation species is Na. + This is produced, and in sodium carbonate, 2Na +Assuming that a reaction occurs, E represents the total molar amount of cation species generated by the addition of the salt compound. E / Al2O3 can change the aggregation state of Al in the mixed gel, which leads to control of the randomness of Al during zeolite crystal formation, making it possible to synthesize GIS-type zeolites with an ideal crystal structure. From the above viewpoint, it is necessary to optimally control E / Al2O3, and E / Al2O3 is preferably 0.1 to 100.0, more preferably 0.5 to 80.0, and even more preferably 0.8 to 50.0.

[0048] Also, water and OH in the mixed gel - The ratio (H2O / OH - ) is important for synthesizing GIS-type zeolites with appropriate SAR. OH - This refers to OH derived from inorganic hydroxides such as NaOH and Ca(OH)2, or organic hydroxides such as tetraethylammonium hydroxide, which are used as alkali sources. - These include substances represented as oxides, such as sodium aluminate and sodium silicate, and the OH released when their hydrates are dissolved in water. - It does not contain [this]. Zeolite formation involves the crystallization of silica, aluminum, and alkali sources dissolved in an aqueous solvent, with some of the material dissolving into the alkaline solvent, creating an equilibrium between crystallization and redissolution. The OH is derived from inorganic hydroxides such as NaOH and Ca(OH)2, and organic hydroxides such as tetraethylammonium hydroxide. - Adding OH to the mixed gel means shifting the equilibrium between crystallization and redissolution towards redissolution. Redissolution proceeds from amorphous or less crystalline areas. Therefore, adding OH appropriately - By increasing the amount of OH, the incomplete crystalline portion can be redissolved and recrystallized repeatedly, thereby increasing the likelihood of forming an ideal crystalline structure. On the other hand, OH - If the amount increases too much, excessive dissolution occurs, resulting in the failure to obtain crystals or the formation of other crystalline phases, such as the more stable ANA-type zeolite. Also, dissolved alumina is more reactive than silica, and alumina is more easily incorporated into crystals. Therefore, OH -By making appropriate adjustments, the rate of crystallization and redissolution can be controlled, and the ratio of silica to alumina incorporated into the crystal can be optimized, thereby optimizing the SAR of the synthesized GIS-type zeolite.

[0049] A higher water-to-alumina ratio (H2O / Al2O3) allows for more uniform dispersion of components in the mixed gel, but if it is too high, it significantly reduces the crystallization rate. Therefore, since it affects the equilibrium between crystallization and redissolution, in order to synthesize a GIS-type zeolite with the optimal SAR and optimal crystal structure, H2O / OH - Along with controlling the other factors, it is necessary to optimally control the H2O / Al2O3 ratio.

[0050] From the above perspective, H2O / Al2O3 and H2O / OH - Preferably, the ratios are 100 ≤ H2O / Al2O3 ≤ 780 and 50 ≤ H2O / OH - ≤1000, more preferably 120 ≤ H2O / Al2O3 ≤ 778 and 60 ≤ H2O / OH - The ratio is ≤800, and more preferably 150 ≤ H2O / Al2O3 ≤ 775 and 70 ≤ H2O / OH - The value is ≤ 700.

[0051] The ratio of silica source to aluminum source in the mixed gel is expressed as the molar ratio of the oxides of each element, i.e., SiO2 / Al2O3. (Note that the silica-alumina ratio of the synthesized zeolite does not match the silica-alumina ratio of the mixed gel. The silica-alumina ratio of the synthesized zeolite is determined by other compositional factors and synthesis conditions.)

[0052] The SiO2 / Al2O3 ratio in this mixed gel is not particularly limited as long as it allows for zeolite formation, but a ratio of 3.0 to 70.0 is preferred, 3.5 to 65.0 is more preferred, and 4.0 to 60.0 is even more preferred, as this ratio tends to suppress the formation of zeolites having a different skeleton from the GIS-type skeleton.

[0053] The ratio of the aluminum source to the alkali metal and alkaline earth metal in the mixed gel is expressed as the added molar ratio of M12O and M2O to Al2O3, i.e., (M12O + M2O) / Al2O3 (where M1 represents an alkali metal and M2 represents an alkaline earth metal. These are calculated as oxides). The (M12O + M2O) / Al2O3 ratio is preferably 1.5 or higher, more preferably 1.6 or higher, and even more preferably 1.65, from the viewpoint of facilitating the formation of GIS-type skeleton crystals. The (M12O + M2O) / Al2O3 ratio is preferably 15.0 or lower, more preferably 12.0 or lower, and even more preferably 10.0 or lower, from the viewpoint of suppressing the formation of zeolites with skeletons different from the GIS-type skeleton.

[0054] The ratio of phosphorus source to aluminum source in the mixed gel is expressed as the molar ratio of oxides of each element, i.e., P2O5 / Al2O3. This P2O5 / Al2O3 is not particularly limited as long as it is a ratio that allows zeolite formation, but it tends to suppress the formation of zeolites having a skeleton different from the GIS type skeleton, so it is preferably less than 1.0, more preferably 0.6 or less, even more preferably 0.4 or less, and especially preferably 0.

[0055] When an organic structural regulator is included in the mixed gel, the ratio of the aluminum source to the organic structural regulator in the mixed gel is expressed as the molar ratio of the organic structural regulator to Al2O3, i.e., R / Al2O3 (where R represents the organic structural regulator). A ratio of less than 7.0 is preferable, more preferably 6.0 or less, and even more preferably 5.0 or less, as this facilitates crystal formation of the GIS-type skeleton and / or shortens the synthesis time, resulting in superior economics when producing zeolites. When an organic structural regulator is used, the organic structural regulator remains in the zeolite pores, preventing carbon dioxide from entering the pores and reducing adsorption. Heating to at least 400°C is necessary to remove the organic structural regulator, but since GIS-type zeolites disintegrate and become amorphous at temperatures above 350°C, it is preferable to use less organic structural regulator. From this perspective, a preferred R / Al2O3 is 4.0 or less, more preferably 3.5 or less, and even more preferably 3.0 or less.

[0056] As described above, the method for producing GIS-type zeolite according to this embodiment includes a step of preparing a mixed gel containing a silica source containing silicon, an aluminum source containing aluminum, an alkali source containing at least one selected from alkali metals (M1) and alkaline earth metals (M2), a salt compound containing at least one selected from alkali metals (M1) and alkaline earth metals (M2), a phosphorus source, and water, and when the molar ratio of each component in the mixed gel is calculated as oxides of each element for silicon, aluminum, alkali metals (M1) and alkaline earth metals (M2), and for the phosphorus source, the following formula (1) It is preferable that the molar ratios α, β, γ, δ, ε, ζ represented by (2), (3), (4), (5), and (6) satisfy 0.1≦α≦100.0, 3.0≦β≦70.0, 1.5≦γ≦15.0, 0≦δ<1.0, 100≦ε≦780, and 50≦ζ≦1000, more preferably that 0.5≦α≦80.0, 3.5≦β≦65.0, 1.6≦γ≦12.0, 0≦δ≦0.6, 120≦ε≦778, and 60≦ζ≦800, and even more preferably that 0.8≦α≦50, 4.0≦β≦60.0, 1.65≦γ≦10.0, 0≦δ≦0.4, 150≦ε≦775, and 70≦ζ≦700. It is particularly preferable that the GIS-type zeolite according to this embodiment is obtained by the method for producing the GIS-type zeolite according to this embodiment described above. α = E / Al2O3 (1) β = SiO2 / Al2O3(2) γ = (M12O + M2O) / Al2O3 (3) δ = P2O5 / Al2O3(4) ε = H2O / Al2O3 (5) ζ=H2O / OH- (6)

[0057] Furthermore, in the method for producing GIS-type zeolite according to this embodiment, if the molar ratios α, β, γ, δ, ε, and ζ satisfy the above range, and the mixed gel further contains an organic structure-determining agent R, it is preferable that the molar ratio η represented by the following formula (7) satisfies η ≤ 4. η = R / Al2O3 (7)

[0058] While it is not always necessary to include seed crystals in the mixed gel, GIS-type zeolite according to this embodiment can also be obtained by adding pre-fabricated GIS-type zeolite as seed crystals to the mixed gel.

[0059] [Preparation process for mixed gel] The preparation steps for the mixed gel are not particularly limited, but may include, for example, a mixing step of mixing a silica source, an aluminum source, a salt compound, water, and optionally a phosphorus source, an alkali source, and an organic structure-defining agent, either all at once or in multiple stages, and a maturation step of the mixture obtained in the mixing step.

[0060] The mixing process can involve mixing a silica source, an aluminum source, a salt compound, water, and optionally a phosphorus source, an alkali source, and an organic structure modifier, either all at once or in multiple stages.

[0061] The order of mixing in multiple stages is not limited and can be selected as appropriate depending on the conditions being used. When mixing in multiple stages, either stirring or non-stirring may be used. When stirring, there is no particular limit to the commonly used stirring method, but specific examples include methods using impeller stirring, vibratory stirring, oscillating stirring, and centrifugal stirring.

[0062] The rotational speed for stirring is not particularly limited as long as it is a commonly used stirring speed, but for example, it may be between 1 rpm and less than 2000 rpm.

[0063] The temperature of the mixing process is not particularly limited as long as it is within the range of commonly used temperatures, but examples include -20°C to less than 80°C.

[0064] The duration of the mixing process is not particularly limited and can be appropriately selected depending on the temperature of the mixing process, but examples include a duration greater than 0 minutes and less than or equal to 1000 hours.

[0065] The maturation process can be carried out either by standing or stirring. When stirring during the maturation process, there are no particular limitations as long as it is a commonly used stirring method, but specific examples include methods using impeller stirring, vibratory stirring, oscillating stirring, and centrifugal stirring.

[0066] The rotational speed for stirring is not particularly limited as long as it is a commonly used stirring speed, but for example, it may be between 1 rpm and less than 2000 rpm.

[0067] The temperature during the maturation process is not particularly limited as long as it is within the range of commonly used temperatures, but examples include a range of -20°C to less than 80°C.

[0068] The maturation time is not particularly limited and can be selected as appropriate depending on the maturation temperature, but examples include a time between 0 minutes and 1000 hours.

[0069] In the zeolite process, it is believed that the raw materials dissolve and zeolite precursors are formed and redissolved during the mixing and maturation processes. To form a large periodic structure containing eight-membered rings without defects, it is preferable that the formation of zeolite precursors is not excessive. Furthermore, if the formation of zeolite precursors is excessive, the formation of ANA-type zeolite, which has a more stable structure, tends to increase, so it is preferable not to over-maturate. On the other hand, it is preferable that the raw materials are thoroughly mixed and that the raw material gel is uniform. The combined time of the mixing and maturation processes is not particularly limited and can be adjusted as appropriate based on the composition of the raw materials to obtain zeolite with an appropriate structure. Typically, the above time is preferably 1 minute or more and less than 24 hours, more preferably 3 minutes or more and less than 23 hours, even more preferably 10 minutes or more and 18 hours, even more preferably 12 minutes or more and 15 hours, and even more preferably 20 minutes or more and 6 hours.

[0070] [Hydrothermal synthesis process] In the method for producing GIS-type zeolite according to this embodiment, it is preferable to further include a hydrothermal synthesis step in which the hydrothermal synthesis temperature is 80°C to 200°C, and more preferably 100°C to 180°C. That is, preferably, the mixed gel obtained in the preparation step is hydrothermally synthesized by holding it at a predetermined temperature for a predetermined time, either by stirring or by standing.

[0071] The temperature for hydrothermal synthesis is not particularly limited as long as it is a commonly used temperature, but it is preferably 80°C or higher from the viewpoint of shortening the synthesis time and being economically superior in the production of zeolites. From the viewpoint of suppressing the formation of zeolites having a skeleton different from the GIS type skeleton, it is more preferably 90°C or higher, and even more preferably 100°C or higher. From the viewpoint of suppressing the formation of zeolites having a skeleton different from the GIS type skeleton, it is more preferably 200°C or lower, even more preferably 180°C or lower, and even more preferably 170°C or lower. The temperature for hydrothermal synthesis may be constant or may be changed in stages.

[0072] The time for hydrothermal synthesis is not particularly limited as long as it is a commonly used time, and can be appropriately selected depending on the hydrothermal synthesis temperature. The time for hydrothermal synthesis is preferably 3 hours or more, and more preferably 10 hours or more, from the viewpoint of forming the GIS framework. From the viewpoint of obtaining highly crystalline GIS-type zeolite, it is even more preferably 24 hours or more. From the viewpoint of economic efficiency in zeolite production, the time for hydrothermal synthesis is preferably 30 days or less, more preferably 20 days or less, and even more preferably 10 days or less.

[0073] In the hydrothermal synthesis process, the container for the mixed gel is not particularly limited as long as it is a commonly used container. However, if the pressure inside the container increases at a predetermined temperature, or if the process is carried out under gaseous pressure that does not inhibit crystallization, it is preferable to use a pressure-resistant container for hydrothermal synthesis. The pressure-resistant container is not particularly limited, and various shapes such as spherical, elongated, or horizontal can be used.

[0074] When stirring the mixed gel in the pressure vessel, the pressure vessel is rotated vertically and / or horizontally, but preferably vertically. When rotating the pressure vessel vertically, the rotation speed is not particularly limited as long as it is within the generally used range, but 1 to 50 rpm is preferred, and 10 to 40 rpm is more preferred.

[0075] In the hydrothermal synthesis process, a method for effectively stirring the mixed gel is to use a vertically elongated pressure vessel and rotate it in the vertical direction.

[0076] [Separation / drying process] After the hydrothermal synthesis process, the solid product and the liquid containing water are separated. The separation method is not particularly limited as long as it is a general method, and can be used such as filtration, decantation, spray drying (rotary spray, nozzle spray, ultrasonic spray, etc.), drying using a rotary evaporator, vacuum drying, freeze-drying, or natural drying. Usually, separation can be achieved by filtration or decantation.

[0077] The separated material can be used as is, or it may be washed with water or a specified solvent. If necessary, the separated material can be dried. The drying temperature is not particularly limited as long as it is a general drying temperature, but is usually between room temperature and 150°C. The atmosphere used for drying is not particularly limited as long as it is a commonly used atmosphere, but is usually an air atmosphere, an atmosphere with an inert gas such as nitrogen or argon, or an atmosphere with added oxygen.

[0078] [Firing process] If necessary, GIS-type zeolite can be calcined and used. The calcination temperature is not particularly limited as long as it is a commonly used temperature, but if it is desired to remove the organic structural modifier, it is preferable to use a temperature of 300°C or higher, and more preferably 350°C or higher, as this reduces the proportion of the organic structural modifier remaining. It is even preferable to use a temperature of 360°C or higher, as this shortens the calcination time and improves the economic efficiency of zeolite production. It is preferable to use a temperature of less than 450°C, more preferably 420°C or lower, and even more preferably 400°C or lower, as this tends to preserve the crystallinity of the zeolite.

[0079] The firing time is not particularly limited as long as it is long enough to sufficiently remove the organic structural modifier, and can be appropriately selected depending on the firing temperature. However, since this tends to reduce the proportion of remaining organic structural modifier, it is preferable to fire for 0.5 hours or more, more preferably 1 hour or more, and even more preferably 3 hours or more. Since this tends to preserve the crystallinity of the zeolite, it is preferable to fire for 10 days or less, more preferably 7 days or less, and even more preferably 5 days or less.

[0080] The firing atmosphere is not particularly limited as long as it is a commonly used atmosphere, but typically an air atmosphere, an atmosphere with an inert gas such as nitrogen or argon, or an atmosphere with added oxygen is used.

[0081] [Cation exchange] If necessary, GIS-type zeolite can be subjected to cation exchange to a desired cation type. Cation exchange is not limited to the following, but for example, carbonates such as sodium carbonate, potassium carbonate, lithium carbonate, rubidium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, and ammonium carbonate; nitrates such as sodium nitrate, potassium nitrate, lithium nitrate, rubidium nitrate, cesium nitrate, magnesium nitrate, calcium nitrate, strontium nitrate, barium nitrate, and ammonium nitrate; salts obtained by changing the carbonate ions and nitrate ions contained in the carbonates and nitrates to halide ions, sulfate ions, carbonate ions, bicarbonate ions, acetate ions, phosphate ions, or hydrogen phosphate ions; and acids such as nitric acid and hydrochloric acid can be used.

[0082] The temperature for cation exchange is not particularly limited as long as it is within the range of typical cation exchange temperatures, but it is usually between room temperature and 100°C or below.

[0083] When separating zeolite after cation exchange, the separation method is not particularly limited as long as it is a general method, and methods such as filtration, decantation, spray drying (rotary spray, nozzle spray, ultrasonic spray, etc.), drying using a rotary evaporator, vacuum drying, freeze-drying, or natural drying can be used, and separation can usually be achieved by filtration or decantation.

[0084] The separated material can be used as is, or it can be washed with water or a specified solvent. If necessary, the separated material can be dried.

[0085] The temperature at which the separated material is dried is not particularly limited as long as it is within the range of typical drying temperatures, but it is usually between room temperature and 150°C.

[0086] The atmosphere used for drying is not particularly limited as long as it is a commonly used atmosphere, but typically, an air atmosphere, an atmosphere with an inert gas such as nitrogen or argon, or an atmosphere with added oxygen are used.

[0087] [Acid treatment] As mentioned above, the cation-exchanged GIS-type zeolite exhibits the aforementioned acid content and peak position P. H and P L In order to bring the acid content within a predetermined range, it is preferable to treat the material with an acidic substance (hereinafter also simply referred to as "acid treatment"). Acid treatment replaces the cation species of the GIS-type zeolite with protons, thereby achieving the aforementioned acid content value.

[0088] Acid treatment is carried out, for example, by stirring GIS-type zeolite in an aqueous solution of an acidic substance.

[0089] The acidic substances used in acid treatment are not particularly limited, but examples include sulfuric acid, nitric acid, hydrochloric acid, phosphoric acid, and acetic acid.

[0090] The acid concentration in an aqueous solution of an acidic substance is preferably 0.01N to 1.00N, more preferably 0.05N to 0.80N, and even more preferably 0.10N to 0.50N, when the acidic substance is a strong acid such as sulfuric acid, nitric acid, and hydrochloric acid. Furthermore, the acid concentration in an aqueous solution of an acidic substance is preferably 0.01N to 5.00N, more preferably 0.1N to 4.00N, and even more preferably 0.50N to 3.00N, when the acidic substance is a weak acid such as phosphoric acid and acetic acid.

[0091] The amount of acid added per gram of GIS-type zeolite is preferably 1 ml / g to 1,000 ml / g, more preferably 2 ml / g to 800 ml / g, and even more preferably 3 ml / g to 500 ml / g.

[0092] The acid treatment may be carried out, for example, under conditions of 0°C to 50°C for 1 to 120 minutes, and multiple acid treatments may be performed.

[0093] [Molded body] The molded article according to this embodiment includes the GIS-type zeolite described above.

[0094] The GIS-type zeolite content may be 50% to 100% by mass, 60% to 99% by mass, 70% to 98% by mass, or 80% to 95% by mass, based on 100% by mass of the total amount of the molded body.

[0095] The molded article according to this embodiment preferably includes a carrier. Examples of carriers include inorganic binders and organic binders.

[0096] Examples of inorganic binders include inorganic oxides such as alumina, silica, magnesia, zirconia, and titania, clay minerals such as bentonite and kaolin, calcium silicate, and calcium aluminate. Examples of alumina include α-alumina, γ-alumina, boehmite, pseudoboehmite, bayerite, gibbsite, and diaspore. Examples of silica include colloidal silica, water glass, fumed silica, silica sol, wet-process silica, dry-process silica, and natural silica. These inorganic binders may be used individually or in combination. Among these inorganic binders, alumina, silica, magnesia, zirconia, and titania are preferred from the viewpoint of increasing the strength of the zeolite molded body, and silica and alumina are more preferred.

[0097] The inorganic binder content is preferably 1% to 99% by mass, more preferably 5% to 90% by mass, and even more preferably 8% to 80% by mass, based on 100% by mass of the total amount of the molded article.

[0098] Examples of organic binders include cellulose, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, latex, polyvinyl alcohol, vinyl acetate, polyvinyl acetal, vinyl chloride, acrylic, polyamide, urea, melamine, phenolic resin, polyester, polyurethane, polyamide, polybenzimidazole, chloroprene rubber, nitrile rubber, styrene-butadiene rubber, polysulfide, butyl rubber, silicone rubber, acrylic rubber, and urethane rubber. These organic binders may be used individually or in combination. Among these organic binders, cellulose, methylcellulose, carboxymethylcellulose, hydroxyethylcellulose, and polyvinyl alcohol are preferred from the viewpoint of surface bonding with GIS-type zeolite, and cellulose, methylcellulose, and polyvinyl alcohol are more preferred.

[0099] The content of the organic binder is preferably 1 to 99% by mass, more preferably 5 to 90% by mass, and even more preferably 8 to 80% by mass, based on 100% by mass of the total amount of the zeolite molded body.

[0100] The total carrier content is preferably 1% to 99% by mass, more preferably 5% to 90% by mass, and even more preferably 8% to 80% by mass, based on 100% by mass of the total amount of the molded body.

[0101] The shape of the molded article according to this embodiment is not particularly limited, but examples include spherical, cylindrical, elliptical, barrel-shaped, clover-shaped, ring-shaped, and powder-shaped. Among these, spherical and cylindrical shapes are preferred.

[0102] Spherical means that the aspect ratio of the molded object is in the range of 1 to 1.1. The aspect ratio of a molded object is the ratio of the major axis to the minor axis when the molded object is stably stationary on a horizontal plane, a projection image of the molded object is taken in the vertical direction, the projection image is sandwiched between two parallel lines tangent to the projection image, the distance between the parallel lines is defined as the largest distance, and the distance between the parallel lines is defined as the smallest distance. The above roundness refers to the value obtained by dividing the difference between the maximum and minimum diameters of any three points measured with a micrometer with a minimum reading of 0.01 mm or less by 2.

[0103] The cross-section obtained by cutting the molded body with a plane passing through any two points on the outer circumference of the molded body is preferably a single circle with a roundness of 0.5 or less, more preferably a single circle with a roundness of 0.4 or less, and even more preferably a single circle with a roundness of 0.3 or less.

[0104] The size of the molded body is not particularly limited, but it varies depending on the situation in which the molded body is used. For example, in processes that use the molded body in non-flowing conditions, such as on a fixed bed or a moving bed, it is preferable that it be spherical with a diameter of 3 mm to 10 mm or cylindrical with a length of 3 mm to 30 mm and a diameter of 1 mm to 30 mm.

[0105] The diameter of the sphere is more preferably 5 mm or more and 8 mm or less. The diameter of the sphere is the average value of the major axis and minor axis used to calculate the aspect ratio of the molded body, and can be adjusted to the above range by operations such as sphere division.

[0106] The length of the cylinder is more preferably 3 mm to 10 mm, and even more preferably 3 mm to 8 mm. The diameter of the cylinder is more preferably 2 mm to 4 mm. The length and diameter mentioned above can be determined by measuring the length and diameter of three pellets using a caliper with a minimum reading of 0.1 mm or less, and then taking the average value of these measurements. These values ​​can then be adjusted to the aforementioned range through operations such as classification.

[0107] For use in processes that utilize a fluidized bed or other fluidized bed, the particles are preferably 20 μm to 300 μm in diameter. More preferably, the particle diameter is 20 μm to 200 μm, and even more preferably 30 μm to 100 μm. The particle diameter is determined using a laser diffraction / scattering particle size analyzer (Microtrac MT3000) according to the accompanying manual, and the median diameter (D 50 It can be measured as follows.

[0108] [Method for manufacturing molded products] The method for manufacturing the molded article according to this embodiment is not particularly limited, but may include a raw material mixing step (X) in which the zeolite in this embodiment is mixed with other optional components (e.g., a carrier) to prepare the product; a molding step (Y) in which the prepared raw materials are subjected to a molding process to obtain a precursor; and a firing step (Z) in which the precursor is fired to obtain a zeolite molded article. In addition, if a desired zeolite molded body can be obtained, the zeolite molded body may be molded by methods such as extrusion molding, injection molding, injection and casting, rolling granulation, compression molding, spray drying, or a combination of two or more of these methods.

[0109] [Raw material mixing process (X)] In the raw material mixing step (X), the raw materials used may be in powder, solvent dispersion, sol, or liquid form, depending on the manufacturing method. Among the raw materials used, for example, when inorganic binders are used, they may be used in powder, solvent dispersion, sol, or liquid form, depending on the manufacturing method, but powder or sol form is preferred from the viewpoint of ease of handling. These inorganic binders may be used individually or in combination.

[0110] The temperature at which the raw materials are mixed is not particularly limited, but for example, 10°C to 80°C is preferred, and 15°C to 60°C is more preferred. For example, in a spray drying process, if the state after mixing the raw materials is slurry, when the temperature of the raw materials is 80°C or lower, evaporation of water in the raw materials tends to be suppressed, and when the temperature of the raw materials is 10°C or higher, freezing in the slurry tends to be suppressed. Also, for example, in an extrusion molding process, if the state after mixing the raw materials is clay-like in the funicular to capillary region, when the temperature of the raw materials is 80°C or lower, evaporation of water from the clay tends to be suppressed, and the amount of water in the clay tends to be kept constant, and when the temperature of the raw materials is 10°C or higher, freezing of water in the clay tends to be suppressed.

[0111] Any means of stirring can be used when preparing the raw materials. For example, when the state after mixing the raw materials is slurry-like, such as in spray drying treatment, stirring blades are preferred. Specifically, examples of blades used for stirring include propeller type, paddle type, flat paddle type, turbine type, and cone type. In addition, baffles or the like may be installed in the tank to ensure efficient stirring. The number of stirrers should be selected to the optimal condition according to the size of the catalyst raw material liquid tank, the shape of the stirring blades, etc. In this embodiment, the total stirring time of the raw materials is preferably 1 minute to 24 hours, more preferably 10 minutes to 5 hours, and even more preferably 15 minutes to 3 hours. When the stirring time of the mixed liquid is 1 minute or more, the composition of the raw materials tends to become uniform, and when it is 24 hours or less, the effect of water evaporation in the raw materials tends to be smaller.

[0112] Furthermore, in processes such as extrusion molding, where the mixture transitions from funicular to capillary clay after mixing, it is preferable to select a mixer or kneader according to the state of the raw materials. In this embodiment, the total mixing and kneading time of the raw materials is preferably 1 minute to 24 hours, more preferably 2 minutes to 5 hours, and even more preferably 3 minutes to 3 hours. When the stirring time of the mixed liquid is 1 minute or more, the composition of the raw materials tends to become more uniform, and when it is 24 hours or less, the effect of water evaporation in the raw materials tends to be smaller. In addition, when an organic binder that easily gels with heat, such as methylcellulose, is included, maintaining the internal temperature of the mixer or kneader at a value lower than the thermal gelling temperature of the organic binder can suppress the gelling of the organic binder, making it easier to obtain raw materials with a uniform composition.

[0113] Furthermore, the clay-like raw material can be left to stand and mature. This maturation process tends to improve moldability as moisture is more easily distributed between the zeolite particles, and also replaces air and other gases present between the zeolite particles, resulting in a denser molded product.

[0114] [Molding process (Y)] Examples of molding processes in the molding process (Y) include extrusion molding, compression molding, and spray drying.

[0115] The extrusion molding process is not particularly limited, but for example, depending on the properties of the raw material used (also called "raw clay" in the extrusion molding process), the temperature during extrusion molding is preferably 10°C to 80°C, and more preferably 15°C to 75°C. The moisture content in the raw clay is preferably 35% to 50% by mass, and more preferably 38% to 45% by mass. When the moisture content is 50% by mass or less, excessive improvement in the flexibility of the raw clay can be prevented, and moldability tends to improve. When the moisture content is 35% by mass or more, a moderate decrease in the flexibility of the raw clay can be prevented, and moldability tends to improve.

[0116] When using an extrusion molding process as the molding process (Y), the extrusion molding machine is not particularly limited, but examples include screw type, roll type, blade type, self-forming type, ram type, and disc pelletizer type. Among these, it is particularly preferable to carry out the extrusion molding process using a roll type, screw type, or disc pelletizer type extrusion molding machine.

[0117] When compression molding is used as the molding process (Y), the compression molding machine is not particularly limited, but examples include uniaxial press molding and hot press molding.

[0118] In spray drying, for example, the slurry can be atomized by methods such as the rotary disc method, the two-fluid nozzle method, and the high-pressure nozzle method, which are commonly used in industry, but the rotary disc method is particularly preferred. As the heat source for drying the sprayed droplets, it is preferable to use air heated by steam, an electric heater, or the like. The temperature at the inlet of the dryer can be around 100°C to 400°C, preferably 150°C to 300°C. The temperature at the outlet of the dryer can be around 40°C to 150°C, preferably 50°C to 130°C.

[0119] [Firing process (Z)] The firing temperature in the firing process (Z) is not particularly limited as long as it is a commonly used temperature, but it is preferably less than 550°C, more preferably 530°C or less, and even more preferably 500°C or less, as this tends to ensure strength while maintaining the crystallinity of the zeolite. Furthermore, the firing temperature is preferably 110°C or higher, and more preferably 120°C or higher.

[0120] The firing time in the firing process (Z) is not particularly limited as long as it is sufficient time for the support to dry and sinter, and can be appropriately selected depending on the firing temperature. However, it is preferable to have a firing time of 20 days or less, more preferably 10 days or less, and even more preferably 7 days or less, as this tends to ensure strength while maintaining the crystallinity of the zeolite.

[0121] The atmosphere used in the firing process (Y) is not particularly limited as long as it is a commonly used atmosphere, but typically an air atmosphere, an atmosphere with an inert gas such as nitrogen or argon, or an atmosphere with added oxygen is used.

[0122] The firing process (Z) can be carried out using firing furnaces such as rotary furnaces, tunnel furnaces, and muffle furnaces.

[0123] The applications of the zeolite molded body according to this embodiment are not particularly limited, and can be used, for example, as a separation agent or separation membrane for various gases and liquids, an electrolyte membrane for fuel cells, a filler for various resin molded bodies, a membrane reactor, a catalyst for hydrocracking and alkylation, a catalyst carrier for supporting metals and metal oxides, an adsorbent, a desiccant, a detergent aid, an ion exchange agent, a wastewater treatment agent, a fertilizer, a food additive, a cosmetic additive, etc. Among the above, the GIS-type zeolite or the molded body thereof according to this embodiment can be suitably used as an adsorbent.

[0124] [Separation method] The separation method according to this embodiment is a method for separating carbon dioxide from a mixed gas containing carbon dioxide and a second component gas different from carbon dioxide using an adsorbent, An adsorption step is performed by bringing the adsorbent into contact with the mixed gas to adsorb carbon dioxide onto the adsorbent, A desorption step is performed by distributing the adsorbent under reduced pressure to remove the carbon dioxide from the adsorbent. Includes, The adsorbent includes the GIS-type zeolite according to the present embodiment described above. In the separation method according to this embodiment, by using an adsorbent containing the GIS-type zeolite described above, the hysteresis of the adsorbent is reduced, and carbon dioxide adsorption and desorption can be performed efficiently.

[0125] [Second component gas] The second component gas can be any gaseous substance other than carbon dioxide. A "gaseous substance" means a substance that is a gas at room temperature (25°C) and atmospheric pressure. Examples of second component gases include methane, ethane, nitrogen, carbon monoxide, hydrogen, argon, and dimethyl ether. Among these second component gases, methane, ethane, and nitrogen are preferred, methane and ethane are more preferred, and methane is even more preferred.

[0126] [Mixed gas] The mixed gas used as a raw material contains carbon dioxide and a secondary component gas. The carbon dioxide content in the mixed gas may be 1% to 99% by volume, 5% to 90% by volume, 10% to 80% by volume, 20% to 70% by volume, or 30% to 70% by volume.

[0127] The content of the second component gas in the mixed gas may be 1% to 99% by volume, 5% to 90% by volume, 10% to 80% by volume, 20% to 70% by volume, or 30% to 70% by volume.

[0128] The moisture content of the mixed gas is preferably 1000 ppm by volume or less, more preferably 500 ppm by volume or less, and even more preferably 100 ppm by volume or less. By keeping the moisture content within this range, it is possible to achieve high adsorption performance of the adsorbent. The moisture content of the mixed gas can be measured, for example, by a dew point meter and converted to moisture content using the method described in JIS Z8806:2001.

[0129] [Adsorption tower] In this embodiment, contact between the adsorbent and the mixed gas may be carried out using an adsorption tower. The adsorption tower may be filled with the adsorbent. The adsorption tower is configured to allow the introduction of the mixed gas and the adsorbent to come into contact with the mixed gas. In the adsorption step, carbon dioxide in the mixed gas is adsorbed onto the adsorbent by bringing the mixed gas into contact with the adsorbent. Since carbon dioxide is adsorbed in the mixed gas, the second component gas can be extracted. Furthermore, after the adsorption step, in the desorption step, carbon dioxide can be extracted by reducing the pressure in the adsorption tower. In this way, purified gas of the second component gas and purified gas of carbon dioxide are obtained in the adsorption step and the desorption step. The adsorption tower may be equipped with a heater to raise the temperature inside the adsorption tower.

[0130] [Conditions for the adsorption and desorption processes] The adsorption and desorption processes may be repeated multiple times. The adsorption process for carbon dioxide is carried out by circulating a mixed gas through the adsorption tower at a pressure close to atmospheric pressure. Subsequently, the adsorption tower is depressurized, and a desorption process is carried out to desorb carbon dioxide from the adsorbent. By repeatedly performing the adsorption and desorption processes in this manner, carbon dioxide and the second component gas are separated. By using the zeolite molded body according to this embodiment, the recovery purity of carbon dioxide and the recovery rate of the second component gas can be increased.

[0131] The ultimate pressure P in the attachment / detachment process. b The ultimate pressure P is preferably 50 kPa or less, more preferably 30 kPa or less, even more preferably 20 kPa or less, even more preferably 15 kPa or less, even more preferably 10 kPa or less, even more preferably 5 kPa or less, and even more preferably 3 kPa or less. b This refers to the pressure near the exhaust outlet of an adsorption tower that is being evacuated under reduced pressure from an adsorption tower filled with adsorbent. The pressure in the adsorption tower gradually decreases due to the reduced pressure evacuation, and eventually reaches a constant pressure.

[0132] The average temperature in the desorption process is preferably 0°C or higher, preferably 10°C to 400°C, more preferably 25°C to 300°C, and even more preferably 25°C to 200°C, from the viewpoint of increasing the efficiency of carbon dioxide desorption and reducing the power required per unit of mixed gas being processed. The average temperature in the desorption process refers to the average temperature of the desorbed gas (carbon dioxide) near the outlet of the adsorption tower during the desorption process. Note that in the desorption process, there is endothermic heat due to the desorption of carbon dioxide from the adsorbent, so the temperature may gradually change.

[0133] Adsorption pressure P in the adsorption process a Adsorption pressure P is preferably 50 to 3000 kPa, more preferably 60 to 500 kPa or less, and even more preferably 70 to 200 kPa or less. a This refers to the pressure near the inlet of the adsorption tower into which the mixed gas is introduced.

[0134] The average temperature in the adsorption process is preferably 0°C or higher, preferably 10°C to 400°C, more preferably 25°C to 300°C, and even more preferably 25°C to 200°C, from the viewpoint of increasing the efficiency of carbon dioxide desorption in the subsequent desorption process and reducing the power required per unit of mixed gas being processed. The average temperature in the adsorption process refers to the average temperature of the gas near the outlet of the adsorption tower during the adsorption process. Note that in the adsorption process, the temperature may gradually change because heat is generated by the adsorption of carbon dioxide onto the adsorbent.

[0135] In the separation method according to this embodiment, the total recovery rate from the mixed gas of carbon dioxide is preferably 90% or more, more preferably 93% or more, and even more preferably 95% or more. Here, the total recovery rate refers to the total amount of carbon dioxide recovered relative to the total amount of carbon dioxide in the mixed gas introduced into the adsorption tower.

[0136] In the separation method according to this embodiment, the total recovery rate of the second component gas from the mixed gas is 90% or more, more preferably 93% or more, and even more preferably 95% or more. The total recovery rate here refers to the total amount of secondary component gas recovered relative to the total amount of secondary component gas in the mixed gas introduced into the adsorption tower.

[0137] In the separation method according to this embodiment, it is preferable that the total recovery rate from the mixed gas of carbon dioxide is 90% or more, and the total recovery rate from the mixed gas of the second component gas is 90% or more, more preferably that the total recovery rate from the mixed gas of carbon dioxide is 93% or more, and the total recovery rate from the mixed gas of the second component gas is 93% or more, and even more preferably that the total recovery rate from the mixed gas of carbon dioxide is 95% or more, and the total recovery rate from the mixed gas of the second component gas is 95% or more.

[0138] The purity of the second component gas obtained by the separation method according to this embodiment is preferably 90% by volume or more, more preferably 93% by volume or more, and even more preferably 95% by volume or more.

[0139] The purity of the carbon dioxide obtained by the separation method according to this embodiment is preferably 90% by volume or more, more preferably 92% by volume or more, and even more preferably 95% by volume or more.

[0140] The water content in the carbon dioxide obtained by the separation method according to this embodiment is preferably 500 ppm by volume or less, more preferably 300 ppm by volume or less, and even more preferably 100 ppm by volume or less. The water content in the carbon dioxide can be measured, for example, by a dew point meter. By using zeolite as an adsorbent in the separation method, the water content in the carbon dioxide can be made lower than the above-mentioned values.

[0141] The separation method according to this embodiment yields purified second component gas or purified carbon dioxide. In other words, the separation method according to this embodiment may be used as a method for producing purified carbon dioxide. Alternatively, the separation method according to this embodiment may be used as a method for producing purified second component gas. The second component gas is as described above, but for example, methane may be used as the second component gas.

[0142] <Activation process> In the separation method according to this embodiment, it is preferable to include an activation step in which the temperature and pressure inside the adsorption tower are raised and reduced to dehydrate the adsorbent. The activation step activates the adsorbent, which adsorbs moisture in the gas to be treated, thereby reducing the moisture content in the resulting carbon dioxide and secondary component gas. It is preferable to perform the activation step before the adsorption step and desorption step described above. Alternatively, the adsorption step and desorption step may be repeated, and the activation step may be performed when the adsorbent has adsorbed a large amount of moisture.

[0143] Ultimate pressure P in the activation process e However, it is preferably 50 kPa or less, more preferably 30 kPa or less, even more preferably 20 kPa or less, even more preferably 15 kPa or less, even more preferably 10 kPa or less, even more preferably 5 kPa or less, and even more preferably 3 kPa or less. Ultimate pressure P e This refers to the pressure near the exhaust outlet of an adsorption tower that is being evacuated under reduced pressure from an adsorption tower filled with adsorbent. The pressure in the adsorption tower gradually decreases due to the reduced pressure evacuation, and eventually reaches a constant pressure.

[0144] The temperature inside the adsorption tower during the activation process is preferably 150°C or higher, more preferably 180°C to 300°C, and even more preferably 200°C to 280°C.

[0145] [Separation device] Referring to Figure 1, the schematic configuration of the separation apparatus 100 according to this embodiment will be described. The separation apparatus 100 includes a mixed gas supply line 1, carbon dioxide adsorption towers 3a and 3b, a carbon dioxide recovery line 5, a second component gas recovery line 7, and a pressure reducing device 9.

[0146] The carbon dioxide adsorption tower 3a has a fixed bed 31a filled with an adsorbent configured to come into contact with the mixed gas introduced inside. One end of the carbon dioxide adsorption tower 3a is connected to the mixed gas supply line 1, and the other end is connected to the second component gas recovery line 7. The second component gas recovery line 7 is equipped with an automatic valve AV3. The second component gas recovery line 7 is also equipped with a flow meter 71, a moisture meter 72, and a component analyzer 73. The component analyzer 73 may be an analyzer capable of measuring the concentration of carbon dioxide and the concentration of the second component gas.

[0147] The carbon dioxide adsorption tower 3a is connected to the carbon dioxide recovery line 5 at the end in the same direction as the end connected to the mixed gas supply line 1. The mixed gas supply line 1 is equipped with a flow meter 11, a moisture meter 12, and a component analyzer 13. An automatic valve AV1 is provided at the inlet of the carbon dioxide adsorption tower 3a. Meanwhile, a pressure reducing device 9 is connected to the carbon dioxide recovery line 5, and the inside of the carbon dioxide adsorption tower 3a is configured to be depressurized. The pressure reducing device 9 may be a vacuum pump. The carbon dioxide recovery line 5 connected to the carbon dioxide adsorption tower 3a is equipped with an automatic valve AV5 and a pressure gauge 53a. Furthermore, the carbon dioxide recovery line 5 is equipped with a flow meter 51, a moisture meter 52, and a component analyzer 54. The component analyzer 54 may be an analyzer capable of measuring the concentration of carbon dioxide and the concentration of the second component gas.

[0148] The carbon dioxide adsorption tower 3b has a fixed bed 31b containing an adsorbent configured to come into contact with the mixed gas introduced inside. An automatic valve AV2 is provided at the inlet of the carbon dioxide adsorption tower 3b. One end of the carbon dioxide adsorption tower 3b is connected to the mixed gas supply line 1, and the other end is connected to the second component gas recovery line 7. An automatic valve AV4 is provided in the second component gas recovery line 7. The carbon dioxide adsorption tower 3b is also connected to the carbon dioxide recovery line 5 at the end in the same direction as the end connected to the mixed gas supply line 1. An automatic valve AV6 and a pressure gauge 53b are provided in the carbon dioxide recovery line 5 connected to the carbon dioxide adsorption tower 3b.

[0149] Next, with reference to Figure 1, the operation of the separation device 100 in this embodiment will be described. A mixed gas is supplied to the carbon dioxide adsorption tower 3a via the mixed gas supply line 1. Carbon dioxide (CO2) contained in the mixed gas is adsorbed by the adsorbent packed inside the carbon dioxide adsorption tower 3a, and a second component gas such as methane (CH4) is recovered from the second component gas recovery line 7. In other words, the carbon dioxide adsorption tower 3a performs an adsorption process in which a mixed gas is introduced into the adsorption tower, carbon dioxide is adsorbed by the adsorbent, and the second component gas is extracted.

[0150] By using a depressurization device 9 to evacuate the carbon dioxide adsorption tower 3a, which contains an adsorbent that has adsorbed carbon dioxide, the adsorbent inside the carbon dioxide adsorption tower 3a is regenerated, and purified carbon dioxide is extracted. In other words, a carbon dioxide desorption process is performed in which carbon dioxide is extracted by evacuating the carbon dioxide from the adsorption tower under reduced pressure.

[0151] As described above, carbon dioxide adsorption towers 3a and 3b repeatedly perform carbon dioxide adsorption by introducing a mixed gas and carbon dioxide desorption by reducing pressure. Therefore, while carbon dioxide adsorption tower 3a is desorbing carbon dioxide, the mixed gas is introduced into carbon dioxide adsorption tower 3b to adsorb carbon dioxide. After carbon dioxide adsorption tower 3a has finished desorbing carbon dioxide, the mixed gas is introduced into carbon dioxide adsorption tower 3a again, and carbon dioxide absorption tower 3b is reduced in pressure to desorb carbon dioxide. In this way, carbon dioxide adsorption and desorption are repeatedly performed in each tower, and the mixed gas can be continuously processed.

[0152] More specifically, it can be operated using the following procedure. Figure 2 is a conceptual diagram showing the time-dependent changes in the pressure fluctuations of carbon dioxide adsorption towers 3a and 3b due to the operation of the separation device 100. Time T in Figure 2 1a With all automatic valves AV1 to AV6 closed, open automatic valves AV1 and AV3, check the flow meter 11 to ensure a predetermined flow rate in the mixed gas supply line 1, and then transfer the mixed gas to the carbon dioxide adsorption tower 3a at an adsorption pressure P. a It is supplied at (for example, 105 kPa). When the carbon dioxide concentration exceeds 5 volume% in the component analyzer 73 (for example, at time T in Figure 3), 1b Alternatively, automatic valves AV1 and AV3 may be closed while automatic valves AV2 and AV4 are opened to switch the supply of the mixed gas from carbon dioxide adsorption tower 3a to carbon dioxide adsorption tower 3b. By switching, the mixed gas is supplied to carbon dioxide adsorption tower 3b at an adsorption pressure P a The carbon dioxide adsorption tower 3a is supplied at a pressure of (for example, 105 kPa). Furthermore, by opening automatic valve AV5 with automatic valve AV3 closed and reducing the pressure using the pressure reducing device 9, the pressure inside the carbon dioxide adsorption tower 3a decreases, bringing the pressure of the carbon dioxide adsorption tower to the target pressure P. b Carbon dioxide is recovered from carbon dioxide adsorption tower 3a by performing the desorption operation at a pressure (for example, 2 kPa). b The time of arrival at T 1c As a result, carbon dioxide adsorbed onto the adsorbent in the carbon dioxide adsorption tower 3a is desorbed, recovering carbon dioxide and regenerating the adsorbent.

[0153] Next, when the carbon dioxide concentration of the gas flowing out of carbon dioxide adsorption tower 3b exceeds 5 volume%, automatic valves AV2 and AV4 may be closed, and automatic valves AV1 and AV3 may be opened to switch the supply of the mixed gas from carbon dioxide adsorption tower 3b to 3a (the relevant time is T 1d (Assuming...). In addition, carbon dioxide is recovered from carbon dioxide adsorption tower 3b by opening the automatic valve AV6 and reducing the pressure with the depressurization device 9 to a pressure of 2 kPa in carbon dioxide adsorption tower 3b and performing the desorption operation. Subsequently, when the carbon dioxide concentration exceeds 5 volume% in the component analyzer 73 (for example, at time T in Figure 2)... 1e Alternatively, automatic valves AV1 and AV3 may be closed while automatic valves AV2 and AV4 are opened, and the supply of the mixed gas may be switched again from carbon dioxide adsorption tower 3a to carbon dioxide adsorption tower 3b.

[0154] The above time T 1a ~T 1d The series of operations up to this point constitutes one cycle C1 of pressure fluctuation in the carbon dioxide adsorption tower 3a. Also, at time T 1b ~T 1e The series of operations up to this point constitutes one cycle C1 of the pressure fluctuation in the carbon dioxide adsorption tower 3b. In other words, cycle C1 includes one adsorption step and one desorption step. By repeating similar operations, the second cycle C2 and the third cycle C3 of the pressure fluctuation may be repeated, with the adsorption and desorption steps being repeated each time.

[0155] The separation device 100 may be applied, for example, to the purification of industrial exhaust gas containing carbon dioxide or biogas obtained by the fermentation of organic matter. Among these applications, it is particularly suitable for the purification of biogas. [Examples]

[0156] The embodiment will be described in more detail below with reference to examples, but this embodiment is not limited to the following examples.

[0157] In this embodiment, various physical properties were measured by the following method.

[0158] [Acid quantity (thermal desorption method (TPD))] The acid content can be measured by the following method using the thermal desorption method (TPD). Approximately 0.05 g of the sample was pre-treated by heating it to 250°C in helium gas, holding it at 250°C for 1 hour, and then cooling it to 100°C. Next, at a sample temperature of 100°C, ammonia gas diluted with helium gas (ammonia concentration in helium is 7.5 vol%; hereinafter also referred to as "7.5%NH3-He") was added to adsorb the ammonia. Afterward, the sample was purged in helium gas for 30 minutes to remove the physically adsorbed ammonia. Then, the temperature was increased from 100°C to 610°C under conditions of a helium gas flow rate of 50 mL / min and a heating rate of 10°C / min, and the amount of desorption was measured. Gas chromatography equipped with a thermal conductivity detector (TCD) was used to detect the desorbed ammonia. The area of ​​the signal obtained from the measurement was calculated as the integrated value of the signal within the temperature range of 300°C to 500°C, without using fitting based on a normal distribution or the like. Using a calibration curve that utilizes the relationship between flow rate and area when 7.5% NH3-He is flowed separately at a predetermined flow rate, the signal area value was converted to the amount of ammonia desorbed. Furthermore, by dividing this value by the mass of the sample after the measurement was completed, the amount of NH3 desorbed per gram of zeolite at 300-500°C (mmol / g) was calculated and defined as the acid content. Regarding the ammonia desorption temperature in TPD measurement, the peak position of the peak with maximum intensity in the temperature range of 300°C or higher is P H (°C), the peak position of the peak with maximum intensity in the temperature range below 300°C is P L (°C)

[0159] [X-ray diffraction] X-ray diffraction was performed using the following procedure. (1) The dried materials obtained in each example and comparative example were used as samples and ground in an agate mortar. (2) The sample from (1) above was uniformly fixed onto a non-reflective sample plate for powders, and the crystal structure was analyzed under the following conditions. X-ray diffractometer (XRD): Rigaku Corporation powder X-ray diffractometer "RINT2500" (product name) X-ray source: Cu tube (40kV, 200mA) Measurement temperature: 25℃ Measurement range: 5~60° (0.02° / step) Measurement speed: 0.2° / min Slit width (scattering, divergence, receiving): 1°, 1°, 0.15mm (3) The obtained X-ray diffraction spectrum was analyzed using the XRD data analysis software "PDXL2" (software name, manufactured by Rigaku Corporation), with the "α cut value" setting in the analysis software set to 3.00. The 2θ value and peak height of the peaks were measured. If no peak was detected, the peak height was set to 0. For the obtained peaks, the B / A value was calculated when the peak heights around 2θ = 12.10° to 13.22° and 17.6° were denoted as A and B, respectively. If the B / A value was 0.10 or greater, and the diffraction peak was between 2θ = 27.55° to 28.74°, the obtained zeolite was determined to be of the GIS type.

[0160] [ 29 [Measurement of Si-MAS-NMR spectra and SAR] The SAR of zeolite in zeolite molded products is 29 This can be determined by measuring Si-MAS-NMR. First, to prepare the zeolite for humidity control, water was placed at the bottom of a desiccator, and the zeolite in a sample tube was kept on top of it for 48 hours. After the humidity control treatment, under the following conditions... 29 Si-MAS-NMR measurements were performed. Equipment: JEOL RESONANCE ECA700 Magnetic field strength: 16.44 T( 1 H resonance frequency 700MHz) Nucleus for measurement: 29 Si Resonance frequency: 139.08MHz NMR tube: 4mm diameter (zirconia rotor) Measurement method: DD / MAS (dipolar decoupling angle magic spinning) Pulse width: 45° Waiting time: 50 seconds Total number of measurements: 800 (Measurement time: approximately 22 hours) MAS: 10,000Hz Chemical shift standard: Silicone rubber (-22.34 ppm) external standard In molded articles containing GIS-type zeolite, 29 The Si-MAS-NMR spectrum shows the following five peaks. (1) Q4(0Al): Peak of Si that is not bonded to Al at all via oxygen. (2) Q4(1Al): Peak of Si bonded to one Al via oxygen. (3) Q4(2Al): Peak of Si bonded to two Al via oxygen. (4) Q4(3Al): Peak of Si bonded to 3 Al via oxygen. (5) Q4(4Al): Peak of Si bonded to 4 Al via oxygen. Also, 29 In Si-MAS-NMR spectra, these peaks are generally located between -112 ppm and -80 ppm and can be attributed to Q4(0Al), Q4(1Al), Q4(2Al), Q4(3Al), and Q4(4Al) from the high-field side. The peak positions may vary depending on the cation species present in the zeolite framework, but generally the peaks are located within the following range. (1) Q4(0Al): -105 ppm to -112 ppm (2) Q4(1Al): -100 ppm to -105 ppm (3) Q4(2Al): -95 ppm to -100 ppm (4) Q4(3Al): -87 ppm to -95 ppm (5) Q4(4Al): -80 ppm to -87 ppm 29The peak area intensity of the Si-MAS-NMR spectrum is obtained by analyzing it using the analysis program dmfit (version #202000113) with Gaussian and Lorentz functions, and optimizing four parameters—amplitude (height of the maximum value of the spectrum), position (spectral position, ppm), width (full width at half maximum of the spectrum, ppm), and Gauss / Lorentz ratio (xG / a (1-x)L)—using a least squares algorithm. The peak areas of Q4(0Al), Q4(1Al), Q4(2Al), Q4(3Al), and Q4(4Al) obtained in this way are A_Q4(0Al), A_Q4(1Al), A_Q4(2Al), A_Q4(3Al), and A_Q4(4Al). If we add up the sum of A_Q4(0Al), A_Q4(1Al), A_Q4(2Al), A_Q4(3Al), and A_Q4(4Al) to get A_total, then the SAR can be calculated as follows. SAR=100 / 〔A_Q4(1Al) / 4+2×A_Q4(2Al) / 4 +3×A_Q4(3Al) / 4+4×A_Q4(4Al) / 4〕×2

[0161] [Measurement of silicon, aluminum, K / Al, and A / T] Zeolite was thermally dissolved in an aqueous sodium hydroxide solution or aqua regia, and the concentrations of silicon, potassium, lithium, and alkali metals in the zeolite were measured using ICP-AES (hereinafter also referred to as "ICP-AES," instrument name: SPS3520UV-DD, manufactured by Seiko Instruments Inc.) by thermal dissolution of the solution and appropriate dilution. 29 The number of aluminum atoms was calculated from the SAR obtained from the Si-MAS-NMR spectrum and the silicon content obtained from ICP-AES. The potassium content in the zeolite was calculated as the ratio of the number of potassium atoms to the number of aluminum atoms (K / Al). Furthermore, it was calculated as the ratio (A / T) of the total amount of potassium and lithium to the total amount of alkali metals (T).

[0162] [CO2 adsorption amount and hysteresis amount; gas adsorption / desorption isotherm measurement] Gas adsorption / desorption isotherm measurements were performed using the following procedure. (1) The dried products obtained in each example and comparative example were used as samples, and 0.2 g was placed in a 12 mm cell (Micro Meritics). (2) The sample placed in the cell described in (1) above was placed in the Micro Meritics gas adsorption analyzer "3-Flex" (product name) and subjected to heating and vacuum degassing treatment at 250°C and 0.001 mmHg or less for 12 hours. (3) The sample placed in the cell after the treatment described in (2) above was placed in constant temperature circulating water at 30°C. After the sample temperature reached 30±0.2°C, the absolute pressure was measured from 0.25 to 760 mmHg using liquefied carbon dioxide (manufactured by Sumitomo Seika Co., Ltd., purity 99.9% by mass or higher). During the above measurement, the pressure was measured over time, and it was determined that the saturation adsorption amount had been reached when the pressure fluctuation became 0.001% / 10 sec or less, and this was recorded as the amount of CO2 adsorbed at 30°C (unit: cc / g). (4) Following the measurements in (3) above, the pressure was gradually reduced from an absolute pressure of 760 to 0.25 mmHg, and the desorption isotherm of carbon dioxide was measured. As with (3), equilibrium was determined when the pressure fluctuation was 0.001% / 10 sec or less. (5) As an index to indicate the amount of hysteresis in the adsorption-desorption isotherm of carbon dioxide, when the equilibrium adsorption amount at the 75 mmHg adsorption isotherm measured in (3) and the equilibrium adsorption amount at the 75 mmHg desorption isotherm measured in (4) are denoted as q(Ad1) and q(De1), respectively, q(Ad1) / q(De1) was used as an index to indicate the amount of hysteresis. When q(Ad1) / q(De1) = 1.00, it indicates that there is no hysteresis, and the smaller q(Ad1) / q(De1), the greater the hysteresis.

[0163] [Thermal stability] As an indicator of the thermal stability of zeolites, the equilibrium adsorption amounts at the 760 mmHg adsorption isotherm measured in (3) of the gas adsorption / desorption isotherm of the zeolite after synthesis and the zeolite after calcination in a muffle furnace at 350°C for 6 hours were denoted as q(Ad2) and q(Ad3), respectively, and q(Ad3) / q(Ad2) was used as an indicator of thermal stability. The closer q(Ad3) / q(Ad2) is to 1, the higher the thermal stability.

[0164] [Example 1] (Synthesis of GIS-type zeolite) A mixed gel was prepared by mixing 56.70 g of water, 0.335 g of sodium hydroxide (NaOH, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), 1.13 g of sodium aluminate (NaAlO2, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 12.42 g of water glass No. 3 (manufactured by Kishida Chemical Co., Ltd.), and stirring for 30 minutes. The composition of the mixed gel was α=SiO2 / Al2O3=8.17, β=Na2O / Al2O3=9.23, γ=H2O / Al2O3=431.0, and δ=R / Al2O3=0.00. The mixed gel was placed in a 200 mL stainless steel microcylinder (manufactured by HIRO COMPANY) containing a fluororesin inner cylinder, and hydrothermally synthesized for 4 days at a stirring speed of 30 rpm and 135°C in a stirring-type constant temperature bath (manufactured by HIRO COMPANY) that allows the microcylinder to rotate vertically. The product was filtered and dried at 120°C to obtain powdered zeolite. XRD spectroscopy confirmed that the obtained zeolite was a GIS-type zeolite. Furthermore, the absence of peaks originating from other zeolites or amorphous silica-alumina led to its evaluation as a high-purity GIS-type zeolite.

[0165] (Potassium exchange in GIS-type zeolite) Two g of the aforementioned GIS-type zeolite was placed in 500 mL of a 0.1 N potassium carbonate aqueous solution prepared using potassium carbonate (K2CO3, manufactured by Nippon Soda Co., Ltd.), and the mixture was stirred at 500 rpm for 3 hours at room temperature. The product was filtered and dried at 120°C to obtain a powdered zeolite in which some of the cations were replaced with potassium. XRD spectroscopy confirmed that the obtained zeolite was a GIS-type zeolite. Furthermore, the absence of peaks originating from other zeolites or amorphous silica-alumina led to its evaluation as a high-purity GIS-type zeolite.

[0166] (Acid treatment of GIS-type zeolite) 1.0 g of the aforementioned GIS-type zeolite was dispersed in 20 g of 0.1 N sulfuric acid to obtain a dispersion. A stirring bar was added to this dispersion and stirred at 25°C for 30 minutes. The product was then filtered and dried at 120°C, followed by acid washing to obtain the GIS-type zeolite. The acid content of the obtained GIS-type zeolite after acid washing was 0.50 mmol / g, and the diffraction peaks obtained by X-ray diffraction were 2θ = 12.63° and 28.49°. The ammonia desorption temperature in the TPD measurement was P H =495℃, P L The temperature was 200°C. Aluminum and silicon concentrations were measured using ICP-AES, and the silica-alumina ratio was calculated to be SAR = 6.9. The potassium concentration was measured, and the potassium concentration in the zeolite was K / Al = 0.21. The alkali metal concentration was also measured, and the ratio of potassium to lithium in the alkali metals was A / T = 0.95. When the adsorption isotherms of CO2 were measured, the values ​​were q(Ad1) / q(De1) = 0.973 and q(Ad3) / q(Ad2) = 0.89.

[0167] [Example 2] 1.0 g of GIS-type zeolite, obtained by synthesis and potassium exchange in the same manner as in Example 1, was dispersed in 20 g of 1N phosphoric acid to obtain a dispersion. A stirring bar was added to this dispersion and stirred at 25°C for 30 minutes. The product was then filtered and dried at 120°C, followed by acid washing to obtain GIS-type zeolite. The acid content of the obtained GIS-type zeolite after acid washing was 0.36 mmol / g, and the diffraction peaks obtained by X-ray diffraction were 2θ = 12.73° and 28.67°, and the ammonia desorption temperature in the TPD measurement was P H =454℃, P LThe temperature was 210°C. Aluminum and silicon concentrations were measured using ICP-AES, and the silica-alumina ratio was calculated to be SAR = 8.2. The potassium concentration was measured, and the potassium concentration in the zeolite was K / Al = 0.40. The alkali metal concentration was also measured, and the ratio of potassium to lithium in the alkali metals was A / T = 0.75. When the adsorption isotherms of CO2 were measured, the values ​​were q(Ad1) / q(De1) = 0.896 and q(Ad3) / q(Ad2) = 0.97.

[0168] [Example 3] (Potassium exchange in GIS-type zeolite) Two g of GIS-type zeolite, synthesized in the same manner as in Example 1, was placed in 500 mL of a 0.02 N potassium carbonate aqueous solution prepared using potassium carbonate (K2CO3, manufactured by Nippon Soda Co., Ltd.), and stirred at 500 rpm at room temperature for 3 hours. The product was filtered and dried at 120°C to obtain a powdered zeolite in which some of the cations were replaced with potassium. XRD spectroscopy confirmed that the obtained zeolite was a GIS-type zeolite. Furthermore, the absence of peaks originating from other zeolites or amorphous silica-alumina led to its evaluation as a high-purity GIS-type zeolite.

[0169] (Acid washing of GIS-type zeolite) 1.0 g of the aforementioned GIS-type zeolite was dispersed in 20 g of 0.2 N sulfuric acid to obtain a dispersion. A stirring bar was added to this dispersion and stirred at 25°C for 30 minutes. The product was then filtered and dried at 120°C, followed by acid washing to obtain the GIS-type zeolite. The acid content of the obtained GIS-type zeolite after acid washing was 0.65 mmol / g, and the diffraction peaks obtained by X-ray diffraction were 2θ = 12.47° and 28.19°. The ammonia desorption temperature in the TPD measurement was P H =481℃, P LThe temperature was 198°C. Aluminum and silicon concentrations were measured using ICP-AES, and the silica-alumina ratio was calculated to be SAR = 8.2. The potassium concentration was measured, and the potassium concentration in the zeolite was K / Al = 0.07. The alkali metal concentration was also measured, and the ratio of potassium to lithium in the alkali metals was A / T = 0.22. When the adsorption isotherms of CO2 were measured, the values ​​were q(Ad1) / q(De1) = 0.978 and q(Ad3) / q(Ad2) = 0.78.

[0170] [Example 4] 1.0 g of GIS-type zeolite, obtained by synthesis and potassium exchange in the same manner as in Example 1, was dispersed in 50 g of 1N acetic acid to obtain a dispersion. A stirring bar was added to this dispersion and stirred at 25°C for 30 minutes. The product was then filtered and dried at 120°C, followed by acid washing to obtain GIS-type zeolite. The acid content of the obtained GIS-type zeolite after acid washing was 0.12 mmol / g, and the diffraction peaks obtained by X-ray diffraction were 2θ = 12.75° and 28.58°. The ammonia desorption temperature in the TPD measurement was P H =448℃, P L The temperature was 188°C. Aluminum and silicon concentrations were measured using ICP-AES, and the silica-alumina ratio was calculated to be SAR = 7.3. The potassium concentration was measured, and the potassium concentration in the zeolite was K / Al = 0.89. The alkali metal concentration was also measured, and the ratio of potassium to lithium in the alkali metals was A / T = 0.96. When the adsorption isotherms of CO2 were measured, the values ​​were q(Ad1) / q(De1) = 0.657 and q(Ad3) / q(Ad2) = 0.98.

[0171] [Example 5] 1.0 g of GIS-type zeolite, obtained by synthesis and potassium exchange in the same manner as in Example 3, was dispersed in 50 g of 5N acetic acid to obtain a dispersion. A stirring bar was added to this dispersion and stirred at 25°C for 30 minutes. The product was then filtered and dried at 120°C, followed by acid washing to obtain GIS-type zeolite. The acid amount of the obtained GIS-type zeolite after pickling was 0.29 mmol / g. The diffraction peaks obtained by X-ray diffraction were 2θ = 12.46° and 28.16°. The ammonia desorption temperature in the TPD measurement was P H = 450 °C, P L = 228 °C. The concentrations of aluminum and silicon were measured by ICP-AES, and the silica-alumina ratio was calculated. As a result, SAR = 8.9. The potassium concentration was measured, and the concentration of potassium in the zeolite was K / Al = 0.02. Also, the alkali metal concentration was measured, and the ratio of potassium to lithium in the alkali metal was A / T = 0.04. When the CO2 adsorption isotherm was measured, q(Ad1) / q(De1) = 0.821 and q(Ad3) / q(Ad2) = 0.28.

[0172] [Comparative Example 1] The acid amount of the GIS-type zeolite synthesized in Example 1 was 0.00 mmol / g. The diffraction peaks obtained by X-ray diffraction were 2θ = 12.46° and 28.14°. The ammonia desorption temperature in the TPD measurement was P H did not exist, P L = 245 °C. The concentrations of aluminum and silicon were measured by ICP-AES, and the silica-alumina ratio was calculated. As a result, SAR = 7.4. The potassium concentration was measured, and the concentration of potassium in the zeolite was K / Al = 0.00. Also, the alkali metal concentration was measured, and the ratio of potassium to lithium in the alkali metal was A / T = 0.00. When the CO2 adsorption isotherm was measured, q(Ad1) / q(De1) = 0.106 and q(Ad3) / q(Ad2) = 0.24.

[0173] The above results are summarized in Table 1.

[0174]

Table 1

[0175] As described above, according to the comparison between the examples and the comparative examples, for GIS-type zeolites with an acid amount of 0.01 mmol / g or more, the adsorption / desorption hysteresis can be reduced. [Industrial applicability]

[0176] The GIS-type zeolite according to the present invention makes it possible to separate, recover, and purify carbon dioxide, and has industrial applicability. [Explanation of Symbols]

[0177] 100 Purified gas production equipment 1. Mixed gas supply line 11 Flowmeter 12 Moisture meter 13 Component analyzer 3a,3b Carbon dioxide adsorption tower 31a,31b Fixed floor 5. Carbon dioxide capture line 53a, 53b Pressure gauge 51 Flow meter 52 Moisture meter 54 Component analyzer 7. Second component gas recovery line 71 Flow meter 72 Moisture meter 73 Component analyzer 9. Pressure reducing device AV1, AV2, AV3, AV4 Automatic Valves

Claims

1. GIS-type zeolite in which the acid content per gram of zeolite at 300-500°C is 0.01 mmol / g or more, as measured by the temperature-controlled desorption method.

2. The GIS-type zeolite according to claim 1, wherein the diffraction peak obtained by X-ray diffraction is between 2θ = 12.10° and 13.22°.

3. The GIS-type zeolite according to claim 1, wherein the diffraction peak obtained by X-ray diffraction is between 2θ = 27.55° and 28.74°.

4. NH 3 - Regarding the ammonia desorption temperature in TPD measurement, the position of the peak with maximum intensity in the temperature range of 300°C or higher is P. H When (°C), 370°C ≤ P H A GIS-type zeolite according to claim 1, satisfying the temperature limit of ≤650°C.

5. NH 3 - Regarding the ammonia desorption temperature in TPD measurement, the position of the peak with maximum intensity in the temperature range below 300°C is P L When denoted as (°C), 185°C ≤ P L A GIS-type zeolite according to claim 1, satisfying the temperature ≤ 250°C.

6. NH 3 For the ammonia desorption temperature in the NH-TPD measurement, when the position of the peak having the maximum intensity in the temperature range below 300 °C is P L (°C), the GIS-type zeolite according to claim 4, satisfying 185 °C ≤ P L ≤ 250 °C.

7. The GIS-type zeolite according to claim 1, wherein the silica-alumina ratio is 3.40 or higher.

8. The GIS-type zeolite according to claim 1, comprising potassium as a cation species in the zeolite.

9. The GIS-type zeolite according to claim 8, wherein the ratio of the number of potassium atoms to the number of aluminum atoms in the zeolite (K / Al) is 0.05 or more.

10. The GIS-type zeolite according to claim 8, wherein the ratio (A / T) of the total amount of substance of potassium and lithium (A) to the total amount of substance of alkali metals (T) in the zeolite is 0.05 or more.

11. A molded article comprising a GIS-type zeolite as described in any one of claims 1 to 10.

12. An adsorbent comprising a GIS-type zeolite as described in any one of claims 1 to 10.

13. A method for separating carbon dioxide from a mixed gas containing carbon dioxide and a second component gas other than carbon dioxide, using an adsorbent, An adsorption step is performed by bringing the adsorbent into contact with the mixed gas to adsorb carbon dioxide onto the adsorbent, A desorption step is performed by distributing the adsorbent under reduced pressure to remove the carbon dioxide from the adsorbent. Includes, A separation method wherein the adsorbent comprises a GIS-type zeolite as described in any one of claims 1 to 10.

14. A method for producing purified carbon dioxide, comprising producing purified carbon dioxide by the separation method described in claim 13.

15. A method for producing purified gas, comprising producing a purified second component gas by the separation method described in claim 13.

16. A carbon dioxide adsorption tower filled with an adsorbent containing a GIS-type zeolite as described in any one of claims 1 to 10, A mixed gas supply line supplies a mixed gas containing carbon dioxide and a second component gas different from carbon dioxide into the carbon dioxide adsorption tower, A depressurization device for reducing the pressure of the carbon dioxide adsorption tower, A carbon dioxide recovery line that recovers carbon dioxide from carbon dioxide adsorption during depressurization, A separation device having

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