Zeolite composite and method for producing the same

Abstract

To provide a zeolite composite which is excellent in mechanical strength, chemical resistance, heat resistance, durability, adsorption and desorption speed, etc., and in chemisorption ability and catalytic ability as zeolite, and has properties excellent in recoverability and handleability of floating on a liquid surface such as water, and to provide a method for manufacturing the zeolite composite by effectively utilizing a natural mineral at low costs in terms of raw materials, equipment and the manufacturing method.SOLUTION: By precipitating zeolite through a chemical reaction on a surface of a support comprising an inorganic solid substance containing a crystal to form an integrated structure chemically bonded, a zeolite composite is obtained in which a surface of a three-dimensional porous body having macropores is zeolitized. Zeolite is precipitated on a surface of a natural mineral or the like used as a raw material through a liquid phase reaction at 150°C or lower.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a zeolite composite and a method for producing the same. More specifically, the present invention relates to a zeolite composite in which zeolite is precipitated over the entire surface of a three-dimensional porous body having macropores, using a crystal-containing inorganic solid substance as a support, and which has excellent mechanical strength, heat resistance, durability, catalytic activity, recoverability, etc. The present invention also relates to a method for producing the zeolite composite using natural minerals or other inorganic solid raw materials through a liquid-phase reaction at 150°C or less, which reduces raw material and production costs. [Background technology]

[0002] Zeolite is a type of clay mineral that can also be artificially synthesized. In typical zeolites, the atomic arrangement of silicon, aluminum, and oxygen forms a framework structure that creates pores of a few angstroms in size, with cations present within the pores to compensate for the framework's negative charge. Zeolite framework structures vary widely, depending on the atomic ratio and production environment (synthesis conditions). The International Zeolite Association assigns a code number to each zeolite framework structure, and as of December 2020, 253 code numbers have been assigned.

[0003] Because the atomic arrangement forms pores, zeolites have extremely small pore sizes of less than 1 nm (10 Å), uniform pore sizes, and three-dimensionally connected pores. Because the pore sizes are on the same order of magnitude as the molecular size, zeolites function as "molecular sieves" that separate specific molecules based on their molecular size. Furthermore, cations within the framework exhibit selectivity based on priority according to ionic radius and valence, and ion exchange properties are known to selectively chemisorb specific ions. Furthermore, this ion exchange ability can be used to give zeolites solid acidic or basic properties. Taking advantage of their molecular sieving, ion exchange, and solid acidic / basic properties, various types of zeolites are widely used as adsorbents, catalysts, fertilizers, and other applications.

[0004] For example, zeolite is used as an industrial catalyst in various manufacturing processes, including petroleum refining and petrochemicals, taking advantage of its properties and heat resistance. It is also used in everyday applications, such as purifying and maintaining water quality in household aquariums, detergents, antiperspirants, and toothpaste. + and Sr 2+ Zeolites that selectively adsorb radioactive materials such as ammonium nitrate and ammonium nitrate are also known and have been used for decontamination at the Fukushima Daiichi Nuclear Power Plant.

[0005] Of the more than 250 types of zeolites, the majority do not exist in nature and can only be obtained through artificial synthesis. The framework structure of a typical zeolite is composed of silicon, aluminum, and oxygen, elements abundant on the Earth's surface. Research and development into zeolite synthesis using natural minerals and industrial waste as raw materials is actively underway. To obtain zeolites, the raw materials must be dissolved and the atoms rearranged to form the zeolite's unique framework, resulting in precipitation. The silicon component of the raw materials, in particular, is typically present as silicon oxide or aluminosilicate, making it difficult to use in reactions due to its low solubility. For example, the high chemical stability and low solubility of silicon oxide can be seen in the fact that laboratory beakers are made of glass, primarily composed of silicon oxide. Therefore, powdered raw materials, which are easily soluble, are used in zeolite synthesis.

[0006] Zeolites obtained from powdered raw materials are naturally in powder form. However, in actual cases where zeolites are used as adsorbents or catalysts, the powder form is not always optimal. For example, bulk zeolites are easy to handle, allowing them to be grasped directly. For bulk zeolites that float on water or oil, such as pumice, the floating zeolites can be scooped up and recovered with a net, dramatically simplifying replacement work. Furthermore, since many solid materials, such as sludge, have a density greater than 1, meaning they sink in water, floating bulk zeolites can be easily separated from these materials in water. Furthermore, because powders tend to float in the air or disperse in water, in situations where this is to be avoided, the powders must be solidified or fixed to a substrate or other material to be used as bulk materials.

[0007] There are three main methods known for obtaining such bulk zeolites and zeolite composites: supporting zeolite on a bulk material, forming a bulk material from zeolite particles, and precipitating zeolite on the surface of a bulk material.

[0008] As the first method for supporting zeolite in a bulk material, for example, a sterilizing, purifying, and deodorizing ball is known, which is formed by coating the surface of a spherical core material made of shirasu balloons with a zeolite membrane (Patent Document 1). This method has the advantage that any type of zeolite can be used as long as it is possible to coat it. However, it has disadvantages such as limitations on the coating area and thickness because the zeolite is coated from the outside, and poor adhesion at the interface between the support and the zeolite, resulting in poor abrasion resistance and durability.

[0009] As the second method for forming a bulk body from zeolite particles, for example, a molded body is known which is obtained by mixing zeolite, an acidic raw material, and a clay raw material, molding, and firing (Patent Document 2). This method has the advantage that it can be molded into any shape. However, because zeolite is a hydroxide containing crystal water, it cannot maintain its crystalline structure up to temperatures near its melting point, and it thermally decomposes or changes to an oxide phase at temperatures several hundred degrees below the melting point. In other words, a sintered body cannot be obtained, and what is obtained is merely a molded body.

[0010] Therefore, the addition of a suitable amount of binder component is required to achieve sufficient mechanical strength for practical use. When organic binders are used with emphasis on bonding, the zeolite has poor light resistance, weather resistance, chemical resistance, and heat resistance. Another disadvantage is the poor adhesion at the interface between the support or additive and the zeolite. It is extremely difficult to achieve ideal porosity and pore distribution while maintaining a certain level of mechanical strength. For example, in a densely molded bulk zeolite, the pore distribution is biased toward ultrafine pores, resulting in poor adsorption / desorption speed and flow rate, i.e., poor processing capacity as a purification material or catalyst.

[0011] Therefore, the present inventors focused on the third method of precipitating zeolite on the surface of a bulk body. As a result of examining related publicly known technologies, they found a soil treatment method using foamed glass with a zeolite surface and an apparatus using the same (Patent Document 3), a membrane in which a zeolite layer is deposited on a porous support (Patent Document 4), and a zeolite membrane formed on a single crystal substrate and preferentially oriented in a specific crystal orientation (Patent Document 5). [Prior art documents] [Patent documents]

[0012] [Patent Document 1] Patent Publication No. 2004-330100 [Patent Document 2] Patent Publication No. 2010-168239 [Patent Document 3] Patent Publication No. 2006-110466 [Patent Document 4] Patent Publication No. 2000-225327 [Patent Document 5] Patent Publication H7-330326 Summary of the Invention [Problem to be solved by the invention]

[0013] However, in these known techniques, zeolite is precipitated by a chemical reaction after a precursor liquid containing raw material components is applied to a bulk support. Therefore, in areas where the precursor liquid cannot penetrate due to surface tension, wettability, viscosity, etc., zeolite does not precipitate uniformly and the coverage area is insufficient. This means that the zeolite has poor chemical adsorption and catalytic properties. Furthermore, because the precursor liquid is added to supplement the Si or Al components that make up the zeolite framework, the concentrations of the Si and Al components are extremely uneven between the support side and the solution side, resulting in a problem of uneven precipitation across the thickness.

[0014] In addition to the above, Patent Document 3 uses glass instead of crystalline oxide, which results in problems with poor mechanical strength, chemical resistance, and heat resistance. Patent Document 3 also has a problem in that it requires high-temperature firing at 400°C or higher in the foaming process, and Patent Document 4 has a problem in that it requires high-temperature firing at 400°C or higher in the chelating agent removal process. Patent Document 5 also has a problem in terms of the manufacturing method, in that it requires a special sol-like raw material.

[0015] The present invention has been made in view of the above-mentioned background art and its problems, and aims to provide a zeolite composite that is excellent in mechanical strength, chemical resistance, light resistance, weather resistance, heat resistance, abrasion resistance, durability, adsorption / desorption rate and flow rate, and chemical adsorption ability and catalytic ability of zeolite. Another aim is to provide a zeolite composite that has the added properties of floating on the surface of liquids such as water, making it easy to recover, separate, and handle. A further aim is to provide a method for producing such a zeolite composite using low-cost raw materials, equipment, and production methods, and that effectively utilizes natural minerals. [Means for solving the problem]

[0016] As a result of intensive research aimed at solving the above-mentioned problems, the present inventors have discovered that a zeolite composite having excellent mechanical strength, chemical resistance, light resistance, weather resistance, heat resistance, abrasion resistance, durability, adsorption / desorption rate, and flow rate can be obtained by chemically precipitating zeolite on the surface of a support made of an inorganic solid material containing crystals to form a chemically bonded integral structure, and then zeolitizing the surface of a three-dimensional porous structure having macropores. Furthermore, the present inventors have discovered that a zeolite composite can be obtained at low cost, making effective use of natural minerals, by using a natural mineral or other inorganic solid raw material that contains crystals and has a three-dimensional porous structure as a raw material and precipitating zeolite on the surface of the raw material through a liquid-phase reaction at 150°C or less. Further research into the structure and manufacturing method of the zeolite composite led to the completion of the present invention.

[0017] That is, the present invention provides a zeolite composite in which a zeolite is chemically bonded to the surface of a support made of a crystal-containing inorganic solid substance, the zeolite composite being a three-dimensional porous body having macropores, and the zeolite is precipitated on all or part of the outer and inner surfaces of the zeolite composite.

[0018] By forming a three-dimensional porous structure using an inorganic solid substance containing crystals as a support, it becomes possible to obtain a product with excellent mechanical strength, chemical resistance, light resistance, weather resistance, heat resistance, abrasion resistance, and durability. Furthermore, by precipitating zeolite on the surface of the support through a reaction between only the components contained in the support and the solution, a structure in which the support and zeolite are uniformly chemically bonded to each other is formed, resulting in excellent adhesion, i.e., excellent abrasion resistance and durability. Furthermore, by forming a three-dimensional porous structure in which zeolite is precipitated even inside the support, it is possible to obtain a bulk body that not only has excellent adsorption ability and catalytic ability, but also has large-diameter macropores, resulting in excellent adsorption / desorption speed, flow rate, etc.

[0019] The present invention also relates to the zeolite composite, wherein the zeolite crystalline phase comprises one or more zeolites selected from the group consisting of CHA zeolite, FAU zeolite, LTA zeolite, GIS zeolite, FER zeolite, ANA zeolite, and SOD zeolite.

[0020] In the liquid phase synthesis of zeolites, the concentration of Si and Al that form the framework structure, and the amount of Na that is incorporated into the structure are important. + , Ca 2+ , K. + The phase of the metastable precipitated zeolite changes depending on the conditions such as the concentration of cations, temperature, pressure, and reaction time. Therefore, by selecting the composition of the inorganic solid material as the raw material and the reaction conditions of the liquid phase reaction, it is possible to precipitate multiple types of zeolite on a support. Zeolite composites in which multiple types of zeolite are precipitated can be produced, for example, by using Cs + , Sr 2+ , NH4 +It is effective for use as a chemical adsorbent that can simultaneously adsorb and remove multiple types of ions such as:

[0021] Furthermore, the present invention relates to the zeolite composite, wherein the main crystalline phase of the zeolite is CHA-type zeolite, FAU-type zeolite, or GIS-type zeolite.

[0022] CHA-type zeolite is a zeolite with pores of 0.38 nm, which is classified as a relatively small diameter among zeolites, and is known to exhibit high adsorption and catalytic properties. By using CHA-type zeolite as the main crystalline phase, it can be used as a chemical adsorbent, for example, for the adsorption of Cs + It is effective as a radioactive material decontamination material that selectively adsorbs NH4 + It can also be used to maintain the water quality of aquariums for fish farmers and home use, and is effective as a catalyst for NOx purification, for example, and can be used as an exhaust gas catalyst in automobiles and factories.

[0023] FAU zeolite is a zeolite with pores of 0.74 nm, which is relatively large among zeolites, and is known to exhibit high adsorption and catalytic properties. By using FAU zeolite as the main crystalline phase, it can be used for pre-purification in air separation, taking advantage of its ability to selectively adsorb carbon dioxide gas. It is also effective as a catalyst for producing hydrocarbons such as gasoline and diesel from heavy oil, and can be used as an oil refining catalyst in petrochemical complexes.

[0024] The present invention also relates to the above-mentioned zeolite composite, wherein the support is derived from a natural mineral containing crystals and having a three-dimensional porous structure.

[0025] For example, the shirasu used in the examples described below contains both crystals and glass. The crystals contribute to the mechanical strength and hardness of the support, while the glass is reactive and serves as a raw material for zeolite. Furthermore, its three-dimensional porous structure contains not only macropores but also mesopores, which are expected to provide superior adsorption / desorption speeds and flow rates compared to micropores, as well as the ability to adsorb and capture molecules and viruses on the order of nanometers or even tens of nanometers. Furthermore, shirasu is an inexhaustible natural resource, covering 50-60% of the mainland area of ​​Kagoshima Prefecture. Using it as a raw material not only offers functional and economic benefits, such as the stable procurement of a raw material with excellent support performance at low cost, but also plays an important social role by effectively utilizing environmental resources.

[0026] Furthermore, the present invention provides a method for producing a granular material having a specific surface area of ​​50 m 2 The zeolite composite is characterized by having a specific surface area of ​​1 / g or more. In the present invention, since the zeolite composite is produced without using a precursor liquid, the zeolite is precipitated at the interface between the raw material support and the solution through a liquid-phase reaction of only the components contained in the raw material and the components contained in the solution. Since the solution penetrates into the interior of the three-dimensional porous body of the raw material, the zeolite is precipitated uniformly on the outer and inner surfaces of the three-dimensional porous body. In other words, the resulting zeolite composite exhibits a high specific surface area. This allows the adsorption and catalytic capabilities of the zeolite to be fully utilized.

[0027] In addition, the present invention provides a method for producing a sintered body having a bulk density of 1 g / cm 3 and a volume of less than 1 mm 3 The zeolite composite is characterized in that the bulk density is 1 g / cm or more. 3 Since the volume is less than 1 mm, the zeolite composite can float on the liquid surface when dropped into a liquid such as water. 3As a result, the zeolite composite of the present invention can be scooped, picked up, or grasped with a net or the like. This allows for the separation of contaminated soil, sludge, etc. in a liquid after purification treatment by taking advantage of the difference in specific gravity, and further prevents powder from flying around or adhering to the container wall due to static electricity, etc. Thus, the zeolite composite of the present invention is excellent in recoverability, separability, and handleability.

[0028] The present invention also relates to the zeolite composite, characterized by carrying a photocatalyst. The zeolite composite of the present invention combines excellent mechanical strength, chemical resistance, light resistance, weather resistance, heat resistance, abrasion resistance, durability, adsorption / desorption rate, flow rate, adsorption capacity, catalytic activity, recoverability, separability, and ease of handling with the organic matter decomposition activity and photoinduced superhydrophilicity of the photocatalyst, making it promising for use as a material capable of water treatment simply by floating it on water. Furthermore, since phytoplankton tend to grow near the water surface where photosynthesis is most easily facilitated, the photocatalytic organic matter decomposition activity can be effectively exerted by utilizing solar energy on the water surface where sunlight is irradiated, breaking down plankton into water and carbon dioxide. Specifically, it can be used to combat red tides and blue-green algae.

[0029] Furthermore, the present invention provides a method for producing the zeolite composite, which comprises using an inorganic solid material containing crystals and having a three-dimensional porous structure as a raw material and precipitating zeolite on the outer and inner surfaces of the inorganic solid material through a liquid-phase reaction at 150°C or less while partially maintaining the crystals and the three-dimensional porous structure. Production under mild synthesis conditions of a liquid-phase reaction at 150°C or less not only reduces production equipment and running costs, but also has advantages in terms of production safety. These advantages are further enhanced when the liquid-phase reaction temperature is 100°C or less.

[0030] The present invention also provides a method for producing the zeolite composite, characterized in that the crystalline phase of the precipitated zeolite contains one or more zeolites selected from the group consisting of CHA zeolite, FAU zeolite, LTA zeolite, GIS zeolite, FER zeolite, ANA zeolite, and SOD zeolite by controlling the composition of the inorganic solid material and the reaction conditions of the liquid-phase reaction, and that the primary crystalline phase of the precipitated zeolite can be selected from CHA zeolite, FAU zeolite, and GIS zeolite. By simply controlling the types of raw materials and the alkali concentration of the liquid-phase reaction, it is possible to form the crystalline phase of the precipitated zeolite from multiple types of zeolite, or to produce the primary crystalline phase of the precipitated zeolite as CHA zeolite, FAU zeolite, or GIS zeolite, depending on the application of the zeolite composite.

[0031] Furthermore, the present invention provides a method for producing the zeolite composite, characterized in that the inorganic solid material is a natural mineral. As in the above, this method not only provides functional and economic benefits such as a stable supply of high-quality raw materials at low cost, but also brings about social benefits such as the effective use of domestic environmental resources. [Effects of the Invention]

[0032] The zeolite composite of the present invention is a zeolite composite in which zeolite is precipitated over the entire surface of a three-dimensional porous body having macropores, using a crystal-containing inorganic solid substance as a support, and is excellent in performance such as mechanical strength, chemical resistance, heat resistance, durability, adsorption / desorption rate, adsorption capacity, catalytic activity, etc. In particular, those having multiple types of zeolites as the crystalline phase or those having CHA-type zeolite or FAU-type zeolite, which are known as highly functional types among zeolites, as the primary crystalline phase can be effectively used for water quality maintenance, water purification, radioactive material removal, exhaust gas catalysts, industrial catalysts, air purification, oil refining, etc.

[0033] Furthermore, the method for producing the zeolite composite of the present invention allows synthesis in a low-temperature process at 150°C or below, resulting in low production costs and high safety. By controlling the reaction conditions, it is possible to produce a zeolite crystalline phase composed of multiple types of zeolite, or to produce a zeolite composed primarily of CHA-type zeolite, FAU-type zeolite, or GIS-type zeolite. Furthermore, using only natural minerals as raw materials not only offers functional and economic benefits such as excellent performance and low raw material costs, but also social benefits such as the effective use of environmental resources. [Brief explanation of the drawings]

[0034] [Figure 1] 1 is a photograph showing the appearance of the Shirasu pumice used as a raw material in Examples 1 to 3. [Figure 2] 1 shows an enlarged observation image (300x magnification) of the Shirasu pumice used as a raw material in Examples 1 to 3, observed with a scanning electron microscope. [Figure 3] 1 shows an enlarged observation image (magnification: 2000 times) of the Shirasu pumice used as a raw material in Examples 1 to 3, observed with a scanning electron microscope. [Figure 4] 1 shows an X-ray diffraction pattern of a sample prepared in Example 1. [Figure 5] 1 is a magnified observation image (100x magnification) of a sample prepared in Example 1 under hydrothermal treatment conditions of 4M, 100°C, and 20 hours, observed with a scanning electron microscope. [Figure 6] 1 is a magnified observation image (magnification: 2000 times) of a sample prepared in Example 1 under hydrothermal treatment conditions of 4M, 100° C., and 20 hours, observed with a scanning electron microscope.

[0035] [Figure 7] 1 is an enlarged image of a sample prepared in Example 1 under hydrothermal treatment conditions of 3M, 100°C, and 20 hours, observed with a scanning electron microscope. [Figure 8] 1 is a graph showing the ammonium ion adsorption rates of a sample (pumice-like) prepared in Example 1 under hydrothermal treatment conditions of 4M, 80°C, and 20 hours, and a sample (powder-like) obtained by pulverizing the same. [Figure 9] 1 shows an X-ray diffraction pattern of a sample prepared in Example 3. [Figure 10] 1 is an enlarged image of a sample prepared in Example 3 under normal pressure treatment conditions of 1M 100° C. for 20 hours, observed with a scanning electron microscope. [Figure 11] 1 shows an X-ray diffraction pattern of a sample prepared in Example 4. [Figure 12] 1 is an enlarged image of a sample prepared in Example 4 under hydrothermal treatment conditions of 2M, 90°C, and 20 hours, observed with a scanning electron microscope.

[0036] [Figure 13] 1 is an enlarged image of a sample prepared in Example 4 under hydrothermal treatment conditions of 2M, 120°C, and 20 hours, observed with a scanning electron microscope. [Figure 14] 1 shows an X-ray diffraction pattern of a sample prepared in Example 5. [Figure 15] 1 is a photograph showing the appearance of perlite used as a raw material in Example 6. [Figure 16] 1 is an enlarged image of perlite used as a raw material in Example 6, observed with a scanning electron microscope. [Figure 17] 1 shows an X-ray diffraction pattern of a sample prepared in Example 6. [Figure 18] 1 is an enlarged image of a sample prepared in Example 6 under hydrothermal treatment conditions of 6M 100°C 2h, observed with a scanning electron microscope. DETAILED DESCRIPTION OF THE INVENTION

[0037] The zeolite composite and its manufacturing method of the present invention will be described in detail below. Note that the structure, characteristics, composition, manufacturing method, etc., which are not described here, may be the same or substantially the same as those known to those skilled in the art.

[0038] The present invention provides a zeolite composite in which a zeolite is chemically bonded to the surface of a support made of a crystal-containing inorganic solid substance, the zeolite composite being a three-dimensional porous body having macropores, and the zeolite is precipitated on all or part of the outer and inner surfaces.

[0039] In the present invention, a "crystal" refers to a substance in which atoms are regularly arranged over a long period. Specifically, a substance in which peaks are detected rather than halo patterns in its X-ray diffraction pattern is called a crystal. Because oriented crystal planes and crystalline phases such as cristobalite, in which peak intensities other than the strongest line are extremely weak, are sometimes present, even if only one strongest line is detected, the substance is considered to be a crystal. Furthermore, even if the support material contains an amorphous material such as glass, if a sample is randomly extracted from this material and a peak is detected in the X-ray diffraction pattern, the inorganic solid material containing a crystal of the present invention is considered to be a crystal-containing inorganic solid material. The measurement conditions for powder X-ray diffraction testing are standard test conditions that a person skilled in the art would use when using an X-ray diffraction testing device, as specifically exemplified in Example 1.

[0040] Examples of the crystalline inorganic solid substance that constitutes the support include silicon oxide, aluminum oxide, titanium oxide, iron oxide, magnesium oxide, calcium oxide, manganese oxide, cobalt oxide, copper oxide, zinc oxide, yttrium oxide, zirconium oxide, palladium oxide, silver oxide, composite oxides thereof, and salts thereof.

[0041] Natural minerals containing these and having a three-dimensional porous structure include feldspars such as alkali feldspar and plagioclase, clays such as kaolinite, montmorillonite, smectite, allophane, zeolite, and layered double hydroxides, rocks, debris, stone, soil, sand, silt, ash, and mixtures thereof, as well as calcium phosphate compounds such as apatite, calcium carbonate compounds, and carbon. Further examples include industrial waste materials such as fly ash, blast furnace slag, and paper sludge incineration ash. These materials may be used after washing, refining, classifying, calcining, mixing, molding, sintering, etc. Among these, the use of natural minerals obtained from natural resources as raw materials is preferred from the viewpoints of expected excellent performance as a support, low cost, and effective utilization of environmental resources.

[0042] The natural mineral used in the present invention is preferably an inorganic solid with heterogeneous crystallinity, containing both crystals and glass (amorphous). Crystals contribute to the mechanical strength and hardness of the support, while glass is reactive and serves as a raw material for zeolites. Natural minerals with three-dimensional porous structures have a wide pore size distribution, possessing not only macropores (50 nm or larger) but also mesopores (2 to 50 nm). This allows for the capture of molecules and viruses on the order of nanometers or tens of nanometers, which macropores lack, and superior adsorption / desorption rates and flow rates compared to micropores (2 nm or smaller). Furthermore, natural minerals contain a wide variety of elements, including Ca, Fe, and K in addition to Si, Al, and Na, making it possible to deposit multiple types of zeolites on a support.

[0043] Natural resources tend to vary in chemical composition, particle size, etc. depending on the extraction site, which leads to variations in the performance of the zeolite composite obtained using them as raw materials, so natural minerals that can be extracted in large quantities in one location or natural minerals with little variation in chemical composition and particle size depending on the extraction site are preferred. Preferred examples of natural minerals that can be expected to perform well as supports and can be extracted in large quantities as homogeneous materials include feldspars such as alkali feldspar and plagioclase, kaolinite, natural zeolite, and pyroclastic pumice.

[0044] The zeolite may be any type as long as its framework structure has been assigned a code number by the International Zeolite Association, and one type or a mixture of two or more types may be used. Among the many types of zeolites, CHA-type zeolite and FAU-type zeolite, which have excellent adsorption and catalytic properties, LTA-type zeolite, which is widely used as an auxiliary agent in detergents, and Cs + GIS-type zeolites, which have the ability to selectively adsorb ammonium hydroxide, are preferred. CHA-type zeolites and FAU-type zeolites, which are known as highly functional zeolites and are expected to have potential for industrial applications, are particularly preferred, and GIS-type zeolites are also particularly preferred when used in contaminated water treatment.

[0045] CHA zeolite is a type of zeolite with relatively small pore diameters of 0.38 nm, which is about the same size as a methane molecule. Only small molecules can diffuse through these pores, while larger molecules such as aromatic compounds are trapped within the zeolite cage. It is one of the zeolites that has been attracting attention in recent years. Cs + It is known that it can selectively adsorb radioactive materials such as NH4 + , Ca 2+ , Mg 2+ It can also be used to remove pollutants such as pollutants and maintain the water quality in aquariums and natural environments.

[0046] Furthermore, it is known to exhibit excellent performance in catalytic applications, for example, as a catalyst for NOx purification and as an industrial catalyst for the process of producing ethylene or propylene from methanol. In the latter example, by using a CHA-type zeolite with solid acidity, the reaction conversion rate can reach 85 to 90%. This allows it to be used, for example, as an automobile exhaust gas catalyst in response to stricter exhaust gas regulations for factories and diesel vehicles, or as an industrial catalyst for manufacturing processes. Although it may be mixed with other types of zeolites, in these applications, it is preferable that the main zeolite crystal phase is CHA-type zeolite, and more preferably, it is a single CHA-type zeolite phase.

[0047] On the other hand, FAU zeolite is a zeolite with a relatively large pore size of 0.74 nm among zeolites. It is also called X-type zeolite (Si / Al<2) or Y-type zeolite (Si / Al>2) depending on its Si / Al ratio, and is one of the most widely used zeolites today. It is known to exhibit the property of selectively adsorbing carbon dioxide gas, and can be used, for example, in pre-purification in air separation. It is also known to be useful as a catalyst for obtaining hydrocarbons such as gasoline and diesel from heavy oil. This allows it to be used as an oil refining catalyst in petrochemical complexes and other facilities. Although it may be mixed with other types of zeolites, in these applications, it is preferable that the main zeolite crystalline phase is FAU zeolite, and even more preferably, it is a single FAU zeolite phase.

[0048] The state in which the support and zeolite are chemically bonded refers to a bond that is defined or described as a chemical bond in chemistry books and literature, such as an ionic bond or a covalent bond, and does not include a state in which the zeolite is simply physically deposited on the support.

[0049] In the present invention, "macropores" are defined as pores with a diameter of 50 nm (0.050 μm) or more, as defined by IUPAC. The zeolite composite of the present invention has a hierarchical pore structure consisting of both macropores and micropores formed by the framework structure consisting of the atomic arrangement of zeolite crystals. Larger macropore diameters result in superior adsorption / desorption rates and flow rates, while smaller macropore diameters result in increased mechanical strength of the zeolite composite, resulting in superior durability and ease of handling. Therefore, the diameter is preferably in the range of 0.1 to 100 μm, and more preferably in the range of 1 to 10 μm.

[0050] The macropores may be artificially formed in the raw material support by mechanical processing or chemical processes such as dissolution, foaming, extraction, removal, etc., but it is necessary to form a plurality of macropores so that they are interconnected. The presence of macropores offers the advantage of excellent adsorption / desorption speed and flow rate, and can realize high-speed reactions in industrial processes such as water treatment and catalysis.

[0051] Furthermore, a "three-dimensional porous body" is a bulk body having a three-dimensional structure with multiple macropores or mesopores. The three-dimensional structure refers to a structure consisting of a three-dimensional pore network, based on a size of 50 nm, which is the lower limit of the diameter of macropores. To exhibit high mechanical strength, the average thickness in the thinnest direction of the coordinate axes in three-dimensional space is preferably 50 μm or more, which corresponds to 1000 times this standard, and more preferably 500 μm or more.

[0052] To that extent, the external shape of the zeolite composite as a bulk body may be in the form of a thin film. In addition to a film, any shape, such as a cube, a rectangle, a polyhedron, a pillar, a sphere, an oval sphere, a pillar, a cylinder, or an irregular shape, may be used. A support preprocessed into any of these shapes may be used as a raw material, or the zeolite composite may be obtained and then processed. Furthermore, the zeolite composite may be crushed to an appropriate size and then packed. Having appropriate macropores of an appropriate size allows for excellent adsorption / desorption speed and flow rate, enabling high-speed reactions.

[0053] The outer surface of a three-dimensional porous body refers to the outer surface of the three-dimensional porous structure as a bulk body. The inner surface of a three-dimensional porous body refers to the surface of the inner walls of the macropores and mesopores of the three-dimensional porous body. Furthermore, "all" includes a form in which zeolite is precipitated on almost the entire surface to the extent that defects or detachment can be recognized in some areas and still be considered equivalent in terms of effectiveness. "Part" includes a form in which zeolite is precipitated on a portion other than the entire surface or on most of the surface. It is preferable that zeolite is precipitated on 10% or more of the area of ​​the outer and inner surfaces, and more preferably on 25% or more of the area.

[0054] The area ratio of zeolite precipitated can be measured by, for example, enlarging and observing the outer surface of the zeolite composite and the inner surface of a sample cut from the zeolite composite, measuring the zeolite coverage area in a given area of ​​multiple observation images, and calculating and using the average value. Alternatively, the specific surface area described below may be used as an indirect index. In this case, the specific surface area (SA) of the zeolite composite after the zeolite treatment is a ) and the specific surface area (SA b ) and the ratio (SA a / SA b ) is preferably 3 or more, more preferably 15 or more.

[0055] The larger the specific surface area of ​​the zeolite composite of the present invention, the greater the reaction area and the more improved the catalytic activity. 2 / g or more, and 200m 2 / g or more is more preferable. The specific surface area refers to the value determined by a BET plot based on an adsorption model using nitrogen gas, known as the N2-BET method. The specific surface area of ​​typical pure zeolite powder is several hundred m 2 / g, and the highest is 700-800m 2 Some zeolites exhibit specific surface areas of 1 / g.

[0056] In conventional zeolite composites, zeolite is supported or precipitated only on the surface of a bulk body using a precursor liquid, so the zeolite exists only near the surface, making it difficult to increase the specific surface area of ​​the entire sample. In the present invention, the surface of a raw material having a three-dimensional porous structure is dissolved and used as a raw material component to precipitate zeolite without using a precursor liquid, so zeolite can be uniformly precipitated evenly on the outer and inner surfaces of the three-dimensional porous body, and this can be controlled by the manufacturing conditions.

[0057] The bulk density of the zeolite composite is 1 g / cm 3If the density is less than 1g / cm3, it will float on the surface of liquids such as water at room temperature. Bulk density is the weight divided by the apparent volume. The density of most solids is 1g / cm3. 3 The zeolite composite floats on the liquid surface, allowing for easy separation in the liquid by taking advantage of the difference in specific gravity between it and the target substance, such as contaminated soil. Furthermore, by combining it with a photocatalyst, it becomes possible to use it for photodecomposition while efficiently utilizing solar energy on the liquid surface, and it is possible to fully utilize not only the floating property in the liquid but also the high specific surface area derived from the micropores of zeolite and the ability to retain adsorbed substances derived from the macropores.

[0058] A large external volume of the zeolite complex is preferable because it is easy to scoop, pinch, or grip with a net, and it prevents powder from flying around or adhering to the container wall due to static electricity, etc. When scooping with a net, the size must be larger than the mesh of the net, and it is recommended to use a mesh size of 1 mm or larger. 3 It is anticipated that the combination of the external size and the property of floating on the liquid surface will be utilized, resulting in excellent recovery from the liquid surface, separation from the target substance such as sludge, and ease of handling during water treatment work.

[0059] When a zeolite composite supports a photocatalyst, the organic matter decomposition activity and surface superhydrophilization activity of the photocatalyst can be utilized. Examples of supported photocatalysts include titanium oxide, zinc oxide, tungsten oxide, and strontium titanate. Among these, titanium oxide is preferred because it is chemically stable, inexpensive, and has high photocatalytic activity. The crystalline phase of titanium oxide is preferably the anatase phase, a metastable phase that has high organic matter decomposition activity and is widely used in practical applications. However, as long as the crystalline phase is primarily anatase, it may also contain a crystalline phase of titanium oxide other than the anatase phase, such as the brookite phase or the rutile phase. Titanium oxide doped with elements such as platinum, copper, iron, silver, gold, cobalt, nickel, vanadium, manganese, and cerium to enhance its activity may also be used.

[0060] Methods for supporting a photocatalyst include dry or wet mixing of a zeolite composite with photocatalyst particles, adding a zeolite composite to a liquid phase containing photocatalyst raw materials and precipitating photocatalyst particles or a photocatalyst coating layer through a liquid-phase reaction, and depositing a photocatalyst on the surface of a zeolite composite in the gas phase by CVD or PVD. When using photocatalyst particles, in order to secure a surface area for photocatalytic activity, it is preferable to use nanoparticles with a number-average diameter of primary particles of 100 nm or less, and more preferably 30 nm or less. Furthermore, if the crystallinity of the photocatalyst particles or photocatalyst coating layer is low, electrons and holes recombine at crystal defects, preventing sufficient organic matter decomposition activity. Therefore, it is preferable for the crystallite size to be 10 nm or more, showing high crystallinity. When coating, the film thickness is arbitrary, but it is preferable for the crystallite size to be 10 nm or more, which is the preferred crystallite size.

[0061] The present invention also provides a method for producing a zeolite composite, characterized by using an inorganic solid material containing crystals and having a three-dimensional porous structure as a raw material, and precipitating zeolite on the outer and inner surfaces of the inorganic solid material by a liquid-phase reaction at 150°C or less while partially maintaining the crystals and the three-dimensional porous structure.

[0062] The meaning of the crystals and three-dimensional porous structure and the type of inorganic solid material referred to here are the same as those of the zeolite composite described above. As long as the material contains crystals and has a three-dimensional porous structure with macropores and mesopores, it is possible to use artificial materials or natural minerals such as pumice as raw materials. Those in the form of fine particles must be molded or combined with other three-dimensional porous materials to form a three-dimensional porous structure.

[0063] The liquid-phase reaction refers to a reaction in which the surface of the raw material is dissolved to precipitate zeolite. The raw material is poured into a basic or acidic liquid to dissolve the surface of the raw material, and the temperature, pressure, and solution concentration are controlled to precipitate zeolite on the surface, thereby obtaining a zeolite composite. If all of the raw material is dissolved, the support referred to in the present invention will not be formed, so it is necessary to control the dissolution reaction and precipitation reaction. Specific examples of production methods are given below.

[0064] Solvents used in liquid-phase reactions include solutions of sodium compounds, potassium compounds, ammonia compounds, fluorine compounds, chlorine compounds, sulfur compounds, nitrogen compounds, and hydrogen peroxide. The solution may be an aqueous solution, an organic solvent, or a mixture of these. Since many natural minerals contain large amounts of silicon, aqueous sodium hydroxide solutions, aqueous potassium hydroxide solutions, and hydrofluoric acid, which easily dissolve silicon, are preferred, and sodium hydroxide and potassium hydroxide, which contain cations that can be incorporated into zeolites, are particularly preferred.

[0065] As mentioned above, in liquid-phase reactions, the temperature, pressure, solution concentration, and reaction time are controlled to control the dissolution and precipitation reactions. In the present invention, the crystals and three-dimensional porous structure of the inorganic solid raw material are left partially intact and used as a support, so milder reaction conditions are desirable than those used in general liquid-phase synthesis of zeolites. The optimal ranges for temperature, pressure, solution concentration, and reaction time vary depending on the raw materials and solvent used.

[0066] For example, from the viewpoint of synthesizing a wider variety of zeolite crystal phases, the temperature range is preferably a slightly higher range of 60 to 150°C, more preferably 85 to 125°C. From the viewpoint of milder synthesis conditions, the temperature range is preferably a slightly lower range of 50 to 100°C, more preferably 75 to 100°C. The pressure may be normal pressure or increased. Specific examples include a method of heating at normal pressure in an open container, a method of heating by circulating the vapor volatilized from the solution back into a liquid using a cooling pipe or the like, and a method of heating in a closed container and then applying pressure under the vapor pressure, known as the solvothermal method (also called the hydrothermal method when an aqueous solution is used). The solution concentration is preferably 1 to 8 M (mol / L), more preferably 2 to 6 M (mol / L). The reaction time is preferably several hours to several days, more preferably 6 to 24 hours.

[0067] Furthermore, in the method for producing a zeolite composite of the present invention, by controlling the raw material composition and the reaction conditions of the liquid-phase reaction, it is possible to configure the crystalline phase of the precipitated zeolite to consist of multiple types of zeolite, or to make the main crystalline phase of the precipitated zeolite CHA-type zeolite, FAU-type zeolite, or GIS-type zeolite. The reaction conditions to be controlled are the raw material composition, type and concentration of the solution, temperature, pressure, and time. Control of the raw material composition, solution concentration, and temperature is particularly important.

[0068] In the examples described below, Shirasu pumice, drift pumice (collected from Yoron Island and Okinoerabu Island), etc. were used as raw materials, and by changing the concentration of sodium hydroxide and the reaction temperature, it was possible to form the crystalline phase of the precipitated zeolite into one or more types of zeolite selected from CHA-type, FAU-type, LTA-type, GIS-type, FER-type, ANA-type, and SOD-type zeolite. Furthermore, it was possible to clearly differentiate the main crystalline phase of the precipitated zeolite into CHA-type, FAU-type, or GIS-type zeolite.

[0069] The phase of the zeolite that metastably precipitates under certain conditions is determined by the concentration of Si or Al dissolved in the solution, or the concentration of cations that intercalate within these crystal structures, as well as the temperature and pressure. The zeolite composite obtained under each reaction condition is thought to be determined by the reaction time, i.e., the reaction rate of the raw materials, changes in ion concentration, and the accompanying phase transition of the zeolite. [Example]

[0070] The zeolite composite and the method for producing the same of the present invention will be specifically described below with reference to examples. Note that the present invention is not limited to these examples, and various modifications are possible within the scope of the technical concept of the present invention.

[0071] [Example 1] Figure 1 shows a photograph of the appearance of Shirasu pumice, a pyroclastic flow deposit collected in Kagoshima Prefecture, and Figures 2 and 3 show enlarged images observed using a scanning electron microscope. The length of each side of the Shirasu pumice was approximately 1 to 10 mm. It can be seen that the Shirasu pumice has a three-dimensional porous structure consisting of macropores. This is a type of Shirasu pumice known as Ito Shirasu, and has a glass to crystalline content ratio of approximately 90:10, with a typical chemical composition of SiO2:Al2O3:Fe2O3:Na2O:K2O:CaO in a weight ratio of approximately 74:12:2:4:4:1.

[0072] When this Shirasu pumice was placed in a beaker filled with distilled water, approximately 83 wt% floated to the surface, and the remainder sank to the bottom. The Shirasu pumice that floated to the surface was collected and used as the raw material for the liquid-phase reaction described below. 1 g of raw material was placed in 6 mL of sodium hydroxide aqueous solution prepared in four stages from 1 to 4 M (mol / L), and the container was sealed in a pressure-resistant container and placed in a dryer set to four stages from 70 to 100 °C. After heating for 20 hours, the mixture was removed from the dryer and subjected to solid-liquid separation by filtration. The solid phase was washed with distilled water and then dried on a hot plate at 100 °C to obtain a sample.

[0073] The appearance of the sample was similar to that of the Shirasu pumice used as the raw material, and it was found to have a three-dimensional porous structure consisting of macropores. When distilled water was poured into a beaker and the sample was added, the sample floated on the water, indicating that the bulk density was 1 g / cm. 3 It was found to be less than

[0074] A portion of the sample was crushed in an agate mortar, and the crystalline phase contained in the sample was investigated using a powder X-ray diffractometer (XRD) under the following conditions. Equipment: Rigaku Corporation Ultima IV Detector: D / tex Ultra Voltage, current: 40kV, 40mA Scan: Continuous ·X-ray: CuKα ray Scan speed: 10° / min. Step width: 0.02°

[0075] The results of powder X-ray diffraction pattern measurements are shown in Figure 4. When hydrothermally treated with 1 to 3 M sodium hydroxide aqueous solutions, peaks attributed to CHA zeolite were observed. Under both the 2 M and 3 M conditions, peaks attributed to CHA zeolite were observed at 80 °C, and more clearly at 90 °C. Under the 3 M and 100 °C conditions, peaks attributed to GIS zeolite were also observed. Under the 4 M conditions, peaks attributed to FAU zeolite were predominant, and peaks attributed to GIS zeolite were also observed at 90 °C and LTA zeolite at 100 °C. In all of these samples, peaks attributed to anorthite (CaAl2SiO8), albite (NaAlSiO3), and quartz (SiO2), the same as those in the raw materials, were also observed.

[0076] The results in Figure 4 show that some of the raw material components dissolved in the liquid phase and reprecipitated to form zeolite, while leaving some of the inorganic solid material, including the raw material crystals, intact. Furthermore, by controlling the reaction conditions, such as the concentration and temperature of the alkaline solution, it was found that the zeolite crystalline phase could be differentiated between those primarily composed of CHA-type zeolite and those primarily composed of FAU-type zeolite, and that single-phase zeolite crystalline phases could be obtained for both CHA-type and FAU-type zeolite.

[0077] In particular, the two known CHA-type zeolites are naturally occurring chabazite and synthetically obtained SSZ-13. However, the synthetic zeolite SSZ-13 is usually synthesized using an organic structure-directing agent, which poses the problem of high raw material costs. In this invention, it has been shown that CHA-type zeolite can be precipitated using a simple, low-cost production method using only natural minerals. Although the mechanism is not entirely clear, it is thought that the potassium contained in Shirasu pumice may play an important role in forming the framework structure of CHA-type zeolite.

[0078] From the above results, in a liquid phase reaction using an alkaline aqueous solution with Shirasu pumice as a raw material, in order to make the main crystalline phase of the zeolite CHA-type zeolite, it is considered that the temperature should be set to 80 to 100°C, the solution concentration to 1 to 3 M, and the reaction time to 12 to 24 hours. Also, in order to make the main crystalline phase of the zeolite FAU-type zeolite, it is considered that the temperature should be set to 70 to 100°C, the solution concentration to 4 to 6 M, and the reaction time to 12 to 24 hours.

[0079] Representative examples of images observed using a scanning electron microscope are shown in Figures 5 to 7. It was found that micron-order granular zeolite was densely deposited on the support surface. Furthermore, it was found that the zeolite particles did not appear to have physically accumulated on the sample surface, but rather that the three-dimensional porous structure of the shirasu raw material served as the support, forming an integrated microstructure on which the zeolite had precipitated.

[0080] To evaluate the performance of the sample, the specific surface area was measured by the N2-BET method and the results are shown in Table 1 below. The specific surface area of ​​the Shirasu pumice used as the raw material was 1.4 m 2 / g, whereas the samples after hydrothermal treatment all showed higher specific surface areas than the raw materials. 2 Some samples exhibiting high specific surface areas up to / g were also confirmed.

[0081] [Table 1]

[0082] In addition, 0.1 g of each sample was added to 25 mL of an aqueous solution with an ammonia concentration of 10 mM at room temperature, and the ammonium ion concentration after 24 hours was measured by ion chromatography to calculate the removal rate. The results are shown in Table 2 below. While the Shirasu pumice used as the raw material did not exhibit any ammonium ion adsorption capacity, all of the samples after hydrothermal treatment exhibited adsorption capacity approximately 2 to 3 times higher than that of a commercially available powdered zeolite (Zeolyst CBV600).

[0083] [Table 2]

[0084] Of the above samples, the one prepared under the 4M, 80°C, 20h conditions was crushed into powder in an agate mortar and the adsorption rate was compared with that of a pumice-like sample. The results are shown in Figure 8. The adsorption rate of the pumice-like sample was found to be faster than that of the powdered sample, indicating that the three-dimensional porous structure with macropores contributes to improving the adsorption rate.

[0085] [Example 2] Each sample obtained in Example 1 above was dropped into an aqueous dispersion of titanium oxide nanoparticles (Degussa P25), and then dried on a hot plate at 100°C, thereby enabling the photocatalyst to be supported.

[0086] [Example 3] Samples were obtained in the same manner as in Example 1, except that they were heated under normal pressure in an open system without using a pressure-resistant vessel. The measurement results of these XRD patterns are shown in Figure 9. As with the results of Example 1, when a 1-3 M sodium hydroxide aqueous solution was used, peaks attributed to CHA zeolite were observed except for the 3 M / 90°C condition, under which a peak attributed to FER zeolite was observed. At a high concentration of 4 M, peaks attributed to FAU zeolite were observed between 70 and 90°C, and under the 4 M / 100°C condition, a peak attributed to SOD zeolite was observed. From the above, it was found that even in liquid-phase reactions under normal pressure, different zeolite phases precipitate depending on the reaction conditions, and that different zeolite phases can be produced.

[0087] A representative example of an image observed by a scanning electron microscope is shown in Figure 10. Similar to the results of Example 1, it was found that micron-order particulate zeolite was densely deposited on the surface of the sample, and that the three-dimensional porous structure of the shirasu raw material served as a support, with the zeolite deposited on the surface to form an integrated structure.

[0088] [Example 4] A sample was obtained in the same manner as in Example 1, except that pumice collected from Yoron Island in Kagoshima Prefecture was used as the raw material and the hydrothermal treatment temperature was set to 90 to 150°C. The results of the crystalline phase investigation by XRD are shown in Figure 11. The XRD pattern of the raw material contains peaks attributable to feldspar and pyroxene as well as peaks attributable to sodium chloride. Considering the time and conditions of collection, this suggests that the raw material is pumice washed ashore from an undersea volcano. Peaks attributable to GIS-type zeolite were confirmed under the 2M / 100°C and 2M / 120°C conditions. It was found that by changing the raw material and controlling the concentration and temperature of the alkaline solution, it is possible to produce GIS-type zeolite as the main crystalline phase of the precipitated zeolite.

[0089] At the higher temperature of 2M at 150°C, peaks attributable to ANA and SOD zeolites were observed in addition to GIS zeolite. At the higher concentration of 4M, peaks attributable to FAU, GIS, and SOD zeolites were observed at the relatively low temperature of 4M at 90°C. At 4M at 100°C, a strong peak attributable to SOD zeolite and a weak peak attributable to GIS zeolite were observed, while at 4M at 120°C and 4M at 150°C, peaks attributable to SOD zeolite were observed.

[0090] As representative examples, SEM images of the 2M90°C sample and the 2M120°C sample are shown in Figures 12 and 13, respectively. Although no peaks attributed to zeolite were observed in the XRD pattern of the 2M90°C sample in Figure 11, the SEM image confirmed the precipitation of zeolite particles. The small amount of zeolite precipitated and its low crystallinity are thought to be the reasons why no peaks were observed in the XRD pattern. Figure 13 confirms that zeolite precipitated tightly on the surface of the pumice raw material, leaving the pore structure of the raw material intact, forming an integrated structure of pumice and zeolite.

[0091] [Example 5] Pumice collected in Wadomari, Oshima County, Okinoerabu Island, Kagoshima Prefecture, was used as the raw material. Samples were obtained in the same manner as in Example 1, except that the hydrothermal treatment temperature was 90 to 150°C and the hydrothermal treatment time was 20 or 40 hours. Figure 14 shows the results of the crystalline phase analysis by XRD. For the same reasons as in Example 4, this raw material is presumed to be pumice washed ashore from an undersea volcano. Under the 2M / 120°C / 40h conditions, peaks attributable to not only GIS zeolite but also CHA zeolite were observed. Under the 2M / 150°C / 20h conditions, peaks attributable to GIS zeolite, ANA zeolite, and SOD zeolite were also observed. Under the 4M / 90°C / 20h conditions, peaks attributable to LTA zeolite were observed in addition to FAU, GIS, and SOD zeolite.

[0092] [Example 6] A photograph of the appearance of perlite (manufactured by Akagi Engei Co., Ltd.) is shown in Fig. 15, and an enlarged image thereof observed by a scanning electron microscope is shown in Fig. 16. Figs. 15 and 16 show that the perlite has a three-dimensional porous structure. Using this perlite, a sample was obtained in the same manner as in Example 1, except that the hydrothermal treatment conditions were a 4 to 6 M aqueous sodium hydroxide solution at 100°C for 2 hours.

[0093] The obtained sample floated on water. Figure 17 shows the XRD pattern measurement results for the obtained sample. Under the 4M condition, peaks attributed to FAU and LTA zeolites were confirmed. Under the 5M and 6M conditions, peaks attributed to SOD zeolite were also confirmed. Under the high concentration condition of 6M, the peaks attributed to FAU and LTA zeolites were weaker, and the peak attributed to SOD was stronger. From the above, it was found that even when perlite was used as a raw material, the zeolite phase that precipitated differed depending on the solution concentration conditions, and that it was possible to produce different zeolite phases.

[0094] A representative example of an image observed by a scanning electron microscope is shown in Figure 18. As in Examples 1 and 3, micron-order particulate zeolite was densely precipitated on the surface of the sample, and it was found that the three-dimensional porous structure of the perlite raw material served as a support, with the zeolite precipitated on the surface to form an integrated structure. [Industrial Applicability]

[0095] The zeolite composite of the present invention is useful as a chemical adsorbent or a water treatment material, for example, for the treatment of Cs + and Sr 2+ It can be used in nuclear power plants as a radioactive material decontamination material that selectively adsorbs carbon dioxide gas. It can also be used for pre-purification in air separation by utilizing its property of selectively adsorbing carbon dioxide gas. + It can also be used to remove such substances and maintain the water quality of aquariums for fish farmers and home use.

[0096] Furthermore, the zeolite composite of the present invention has excellent recoverability, separability, and ease of handling. For example, it can be scattered in water or oil and recovered with a net. Taking advantage of these characteristics, it can be used for water treatment and other purposes, even in situations where delicate work, such as with remote-controlled robots, is difficult. In other words, it can contribute to solving urgent issues facing Japan, such as the social problems of aging workers and labor shortages in the primary industry, and the environmental problem of decontaminating radioactive materials at nuclear power plants.

[0097] Furthermore, the zeolite composite of the present invention is easy to handle and has macropores, which allows for low pressure loss and high flow rates, i.e., excellent processing speed. It can be used as a catalyst, for example, as an exhaust gas catalyst in automobiles or factories as a NOx purification catalyst. It can also be effectively used as a catalyst for obtaining hydrocarbons such as gasoline and diesel from heavy oil, and can be used as an oil refining catalyst in petrochemical complexes.

[0098] Furthermore, by supporting a photocatalyst, the properties of the zeolite composite can be combined with its organic matter decomposition activity, and it can be used, for example, as a water treatment material that can purify water and maintain water quality simply by floating it on the water surface. In particular, phytoplankton, which cause blue-green algae and red tides, use photosynthesis and tend to grow near the water surface, and solar energy can be efficiently utilized on the water surface. Therefore, photocatalyst-supported zeolite composites that float on the water surface are highly useful. In this application, the high adsorption capacity due to the high specific surface area of ​​the zeolite composite and the high adsorption rate and retention capacity of the target substance due to the macropores can be combined with the organic matter decomposition activity of the photocatalyst.

[0099] The method for producing a zeolite composite of the present invention can produce a zeolite composite, which is expected to be useful in various industrial fields as described above, using only natural minerals as raw materials and a low-temperature reaction at 150°C or less. For example, the shirasu used in the examples is a natural resource that is considered inexhaustible, covering 50-60% of the mainland area of ​​Kagoshima Prefecture. Large amounts of pumice washed ashore in various locations due to submarine volcanic eruptions have had a significant impact on the fishing and tourism industries, and the high cost of disposal after recovery makes it a major social problem, similar to disaster waste. Perlite is a commercially available gardening product sold for several hundred yen per kilogram. The present invention allows the use of a variety of inorganic resources, and offers economic benefits such as low costs for raw materials, equipment, and production methods, as well as social benefits such as the effective use of environmental resources. It is expected to greatly contribute to industrial development.

Claims

1. A zeolite composite in which zeolite is chemically bonded to the surface of a support made of an inorganic solid material containing crystals, It is a three-dimensional porous body having macropores, The support is made of a natural mineral that contains crystals and forms a three-dimensional porous structure having macropores, the macropores possessed by the support and the three-dimensional porous body include macropores with a diameter of 10 μm or more; The volume of the three-dimensional porous body is 1 mm 3 or more, A zeolite composite, characterized in that the zeolite is precipitated on all or part of the outer and inner surfaces of the three-dimensional porous body.

2. 2. The zeolite composite according to claim 1, wherein the zeolite crystalline phase comprises one or more zeolites selected from the group consisting of CHA-type zeolite, FAU-type zeolite, LTA-type zeolite, GIS-type zeolite, FER-type zeolite, ANA-type zeolite, and SOD-type zeolite.

3. 2. The zeolite composite according to claim 1, wherein the main crystalline phase of the zeolite is CHA-type zeolite, FAU-type zeolite, or GIS-type zeolite.

4. Specific surface area is 50m ２ 4. The zeolite composite according to claim 1, wherein the zeolite composite has a molecular weight of 1 / g or more.

5. Bulk density is 1 g / cm ３ 5. The zeolite composite of claim 1, wherein the zeolite composite has a molecular weight of less than 10 ...

6. The zeolite composite according to claim 1 , which supports a photocatalyst.

7. 7. A method for producing a zeolite composite according to claim 1, wherein a natural mineral containing crystals and having a three-dimensional porous structure is used as a raw material, and zeolite is precipitated on the outer and inner surfaces of the natural mineral by a liquid-phase reaction at 150°C or less while partially maintaining the crystals and the three-dimensional porous structure.

8. 8. The method for producing a zeolite composite according to claim 7, wherein the temperature of the liquid phase reaction is 100°C or lower.

9. 8. A method for producing a zeolite composite according to claim 7, characterized in that the crystalline phase of the zeolite to be precipitated contains one or more zeolites selected from the group consisting of CHA zeolite, FAU zeolite, LTA zeolite, GIS zeolite, FER zeolite, ANA zeolite, and SOD zeolite by controlling the composition of the raw materials and the reaction conditions of the liquid-phase reaction.

10. 8. The method for producing a zeolite composite according to claim 7, wherein the main crystalline phase of the zeolite to be precipitated can be selected from CHA-type zeolite, FAU-type zeolite, and GIS-type zeolite by controlling the composition of the raw materials and the reaction conditions of the liquid-phase reaction.

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