Faujasite-type zeolite

Abstract

To provide a faujasite-type zeolite having a reduced proportion of Bronsted acids with high acid strength.SOLUTION: A faujasite-type zeolite has: a molar ratio of SiO2 / Al2O3 in a range of 40 or more and 200 or less; a crystallinity in a range of 0.20 or more and 1.00 or less; a Bronsted acid amount in a range of 20 μmol / g or more and 400 μmol / g or less, as measured by pyridine-adsorbed FT-IR after evacuation at 150°C; and a proportion of the Bronsted acid amount, measured after evacuation at 450°C, of less than 65%, relative to the Bronsted acid amount measured after evacuation at 150°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a faujasite-type zeolite having high acid strength and low Bronsted acidity. [Background technology]

[0002] Zeolite is a general term for crystalline porous aluminosilicates. Among these, faujasite-type zeolites, which have strong solid acidity and relatively large micropores, have long been used as catalyst components in oil refining and petrochemical industries.

[0003] It has long been known that solid acids of zeolites can act as catalysts in hydrocarbon cracking reactions, and for example, faujasite-type zeolites are widely used as components of fluid catalytic cracking catalysts and hydrocracking catalysts.

[0004] The solid acid of zeolite is mainly composed of protons (H + ) and are also called acidic hydroxyl groups. Protons are also commonly called Brønsted acids, and the Brønsted acidity of zeolites is determined by the amount of Al in the zeolite framework. To adjust the amount of Al in the zeolite framework, a method is used to adjust the framework SiO2 / Al2O3 ratio of the zeolite.

[0005] Known methods for adjusting the framework SiO2 / Al2O3 ratio of faujasite-type zeolite include a combination of hydrothermal treatment with water vapor and acid treatment (see Patent Documents 1 and 2), EDTA treatment, and dealumination treatment such as ammonium hexafluorosilicate treatment (see Non-Patent Document 1). By using such treatments, it is possible to adjust the framework SiO2 / Al2O3 ratio of faujasite-type zeolite and obtain faujasite-type zeolite having a desired Bronsted acidity.

[0006] The amount and strength of Bronsted acid in zeolite affect the activity and selectivity of hydrocarbon cracking reactions. For example, it has been reported that a hydrocracking catalyst using highly dealuminated, extremely low acidity USY together with silica-alumina has improved catalytic activity and increased total distillate yield (see Patent Document 3).

[0007] It has also been reported that by using a faujasite-type zeolite with reduced strong acid sites in a hydrocracking catalyst, high selectivity to middle distillates can be obtained even in a region where cracking activity is high (see Patent Document 4). A method of adding alkaline earth metals or rare earths to reduce the strong acid sites of zeolites is known (see Patent Document 4 and Non-Patent Document 2). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 7145343 [Patent Document 2] Japanese Patent Publication No. 2023-90424 [Patent Document 3] Special Publication No. 2006-505671 [Patent Document 4] Patent Publication No. 2021-151641 [Non-patent literature]

[0009] [Non-Patent Document 1] Yoshio Ono and Takeaki Yashima (eds.), "The Science and Engineering of Zeolites", 1st edition, Kodansha, July 10, 2000, pp. 119-134 [Non-patent document 2] Yoji Sano, Journal of the Petroleum Society, Vol. 35, No. 6, pp. 429-440, 1992 Summary of the Invention [Problem to be solved by the invention]

[0010] The methods of Patent Documents 1 and 2 and Non-Patent Document 1 can adjust the acid amount of the Brønsted acid in the faujasite zeolite, but have the problem that it is difficult to change the acid strength of the Brønsted acid. Also, the methods of Patent Document 4 and Non-Patent Document 2 have the problem that the alkaline earth metal ions and rare earth ions added to reduce the Brønsted acid with high acid strength in the zeolite are desorbed during use as a catalyst, causing the Brønsted acid with high acid strength to return and increase in its proportion.

[0011] In light of these circumstances, an object of the present invention is to provide a faujasite-type zeolite in which the proportion of Bronsted acids, which have high acid strength, is reduced without adding alkaline earth metal ions or rare earth ions. [Means for solving the problem]

[0012] The present inventors attempted to reduce the acid strength of Brønsted acids by generating irregularities in the framework structure while maintaining the faujasite zeolite framework. Specifically, they found that by specifying the hydrothermal treatment conditions, the temperature of the acid treatment, or the amount of acid added, irregularities are generated in the framework structure while maintaining the crystal structure of faujasite zeolite, and the proportion of Brønsted acids with high acid strength can be reduced.

[0013] That is, the faujasite-type zeolite of the present invention has a SiO2 / Al2O3 molar ratio in the range of 40 to 200, a crystallinity in the range of 0.20 to 1.00, a Brønsted acid amount in the range of 20 to 400 μmol / g as measured by pyridine adsorption FT-IR after evacuation at 150°C, and a ratio of the Brønsted acid amount measured after evacuation at 450°C to the Brønsted acid amount measured after evacuation at 150°C of less than 65%.

[0014] With this configuration, a faujasite-type zeolite having a reduced proportion of Bronsted acids with high acid strength can be obtained. [Effects of the Invention]

[0015] According to the present invention, it is possible to reduce the proportion of Bronsted acids with high acid strength while maintaining the crystal structure of faujasite-type zeolite. DETAILED DESCRIPTION OF THE INVENTION

[0016] The faujasite-type zeolite of the present invention will be described in detail below.

[0017] The faujasite-type zeolite of the present invention (hereinafter also referred to as "the zeolite of the present invention") is a zeolite in which the proportion of the amount of Bronsted acids with high acid strength to the total amount of Bronsted acids is determined by the ratio of the areas of pyridine adsorption IR spectra at different exhaust temperatures, and this proportion is reduced. Specifically, the amount of acid calculated from the area of ​​the pyridine adsorption FT-IR spectrum after exhaust at 150°C is defined as the total amount of Bronsted acids, and the amount of acid calculated from the area of ​​the pyridine adsorption IR spectrum after exhaust at 450°C is defined as the amount of Bronsted acids with high acid strength, and the proportion of these is set to less than 65%.

[0018] The zeolite of the present invention must have an SiO2 / Al2O3 molar ratio (hereinafter also referred to as the silica-alan ratio) in the range of 40 to 200, preferably in the range of 50 to 200. This silica-alan ratio is calculated from the composition ratio of the zeolite of the present invention. The higher this silica-alan ratio, the higher the silica-alan ratio in the framework, and the amount of Al in the framework and the amount of Brønsted acid tend to decrease. By setting the silica-alan ratio in the range of 40 to 200, the amount of Brønsted acid can be optimized. If the silica-alan ratio is too high, the amount of Al in the framework will decrease, leading to a decrease in the amount of Brønsted acid. Therefore, it is more preferable that the silica-alan ratio of the zeolite of the present invention be in the range of 50 to 150.

[0019] The crystallinity of the zeolite of the present invention must be in the range of 0.20 to 1.00, preferably 0.35 to 0.95. The crystallinity of a zeolite affects its durability and solid acidity. In the present invention, the intensity of the diffraction peak derived from the faujasite crystal structure obtained by X-ray diffraction measurement is used as an index of the crystallinity of the zeolite. Specifically, a faujasite-type zeolite obtained by a specific method is used as a standard substance, and the intensity ratio of the peak derived from the faujasite structure obtained by X-ray diffraction measurement is defined as the crystallinity of the zeolite of the present invention. By adjusting the crystallinity within the above-mentioned range, the proportion of Bronsted acids with high acid strength can be reduced while maintaining the crystal structure of the faujasite-type zeolite. Zeolites with a crystallinity of less than 0.20 do not maintain the faujasite crystal structure. The crystallinity of the zeolite of the present invention more preferably ranges from 0.50 to 0.90. The crystallinity measurement method is as described in the Examples below.

[0020] The zeolite of the present invention must have a Bronsted acidity in the range of 20 μmol / g to 400 μmol / g, preferably 30 μmol / g to 300 μmol / g, as measured by pyridine adsorption FT-IR after evacuation at 150°C. The objective of the present invention is to reduce this Bronsted acidity. If the Bronsted acidity is too low, the activity and selectivity of the hydrocarbon cracking reaction will be insufficient. Therefore, the zeolite of the present invention more preferably has a Bronsted acidity in the range of 40 μmol / g to 150 μmol / g. Furthermore, the ratio of the Bronsted acid amount measured after evacuation at 450°C to the Bronsted acid amount measured after evacuation at 150°C must be less than 65%, and preferably 60% or less. If this ratio exceeds 65%, the ratio of Bronsted acids with high acid strength relative to the total acid amount of Bronsted acids will be too high, resulting in insufficient selectivity for the hydrocarbon cracking reaction. The method for measuring these Bronsted acid amounts is as described in the Examples below.

[0021] The lattice constant of the zeolite of the present invention is preferably in the range of 2.410 nm or more and 2.429 nm or less, and more preferably in the range of 2.415 nm or more and 2.425 nm or less. In the present invention, the lattice constant is an index showing the silica-aluminum ratio of the framework of the zeolite of the present invention. When the amount of aluminum in the framework increases (the silica-aluminum ratio of the framework decreases), the lattice constant increases, and when the amount of aluminum in the framework decreases (the silica-aluminum ratio of the framework increases), the lattice constant decreases. When this lattice constant is in the above-mentioned range, the acid strength of the Bronsted acid tends to decrease.

[0022] The zeolite of the present invention has a specific surface area of ​​650 m 2 / g or more, and 2 The higher the specific surface area, the better, but the upper limit is 850 m 2 / g or less. Zeolites generally have an extremely large specific surface area due to the pore structure derived from their skeleton. When this specific surface area is within the above-mentioned range, the zeolite skeleton is maintained, and a Bronsted acidity corresponding to the amount of Al in the skeleton can be secured.

[0023] The zeolite of the present invention preferably has a Na content of 0.5% by mass or less, more preferably 0.2% by mass or less, and particularly preferably 0.1% by mass or less, calculated as Na2O. + The Na content in the above range is preferred because it increases the solid acidity of the zeolite.

[0024] The zeolite of the present invention can be prepared by acid treating a faujasite-type zeolite having a crystal lattice size within a specific range and many defects with an acid solution containing an excess amount of acid at a specific temperature range. The crystal lattice size is expressed as the lattice constant. Furthermore, since a faujasite-type zeolite having many defects will have a larger water adsorption capacity than a faujasite-type zeolite having few defects, the water adsorption capacity of the faujasite-type zeolite was used as an index of defects in this production method. The reason why a faujasite-type zeolite having many defects has a larger water adsorption capacity is because it has a large number of silanol groups and a high affinity for water.

[0025] The zeolite of the present invention can be prepared, for example, by a production method comprising an acid treatment step of treating a faujasite-type zeolite having a lattice constant in the range of 2.430 nm to 2.440 nm and a water adsorption amount in the range of 10% to 23% with an acid solution, wherein the temperature of the acid solution is in the range of 20°C to 50°C, and the molar number of protons derived from the acid contained in the acid solution is in the range of 3.0 to 8.0 relative to the molar number of Al contained in the faujasite-type zeolite. This production method is referred to as the present production method and is described in detail below.

[0026] The present production method includes an acid treatment step of treating, with an acid solution, faujasite-type zeolite having a lattice constant in the range of 2.430 nm to 2.440 nm and a water adsorption amount in the range of 10% to 23%. In this step, it is preferable to treat, with an acid solution, faujasite-type zeolite having a lattice constant in the range of 2.435 nm to 2.440 nm. It is also preferable to treat, with an acid solution, faujasite-type zeolite having a water adsorption amount in the range of 17% to 23%. This faujasite-type zeolite may be purchased and processed from a commercial source, or may be synthesized by a conventionally known method. For example, faujasite-type zeolite can be synthesized by adding a Si raw material, an Al raw material, and then adding a Na raw material and water, followed by hydrothermal treatment at a temperature in the range of 80°C to 120°C. If the lattice constant of the faujasite-type zeolite obtained in this manner is not within the above-mentioned range, the lattice constant can be adjusted to some extent by ion-exchanging the ion exchange sites of the faujasite-type zeolite with ammonium ions and then steaming the zeolite. The steaming is preferably performed at a temperature in the range of 400°C to 800°C. When the faujasite-type zeolite is steamed in this manner, Al is extracted from the faujasite skeletal structure, thereby reducing the lattice constant. Furthermore, after Al is extracted from the faujasite skeletal structure, some of the Al is re-inserted with Si, forming a framework, while some of the Si is not re-inserted, forming defects. By adjusting the steaming conditions and temperature, the proportion of Si re-inserted after Al is extracted from the faujasite skeletal structure can be controlled, thereby obtaining a faujasite-type zeolite with a crystal lattice size and defect count within the desired range.

[0027] In this step, it is preferable to use a faujasite-type zeolite having a silica-alan ratio in the range of 4 to 10, and it is more preferable to use a faujasite-type zeolite having a silica-alan ratio in the range of 5 to 9. Faujasite-type zeolite having a silica-alan ratio in this range is likely to have a lattice constant within the above-mentioned range.

[0028] In this step, it is preferable to use a faujasite-type zeolite having a crystallinity in the range of 0.75 to 2.00, and it is more preferable to use a faujasite-type zeolite having a crystallinity in the range of 0.80 to 1.50. When a faujasite-type zeolite having a crystallinity in the above range is used, it is possible to impart irregularity to the faujasite-type zeolite while maintaining its framework structure in the acid treatment step.

[0029] In this step, the faujasite-type zeolite is acid-treated using an acid solution. The temperature of this acid solution is in the range of 20°C to 50°C, and preferably in the range of 35°C to 45°C. By adjusting the temperature of the acid solution to a low temperature in this manner, it is possible to impart irregularity to the skeletal structure while maintaining it.

[0030] In this step, the molar amount of protons derived from the acid contained in the acid solution relative to the molar amount of Al contained in the faujasite-type zeolite is preferably in the range of 3.0 to 9.0, and more preferably 4.0 to 8.0. In this way, by adjusting the molar amount of protons derived from the acid contained in the acid solution to be three times or more the molar amount of Al contained in the faujasite-type zeolite, it is possible to impart irregularity to the framework structure.

[0031] In this step, the acid contained in the acid solution may be any known inorganic acid, such as sulfuric acid, nitric acid, or hydrochloric acid, and sulfuric acid is preferred.

[0032] In this step, the acid treatment is preferably carried out for 0.5 to 8 hours, more preferably 0.5 to 6 hours. By carrying out the acid treatment for such a relatively short time, it is possible to impart irregularity to the framework structure of the faujasite zeolite while maintaining the framework structure.

[0033] The present production method may include various steps after the acid treatment step, as long as the steps do not impair the characteristics of the zeolite of the present invention that is finally obtained. For example, the method may include an ion exchange step, a filtration step, a washing step, a drying step, a calcination step, an acid treatment step, or a molding step. [Example]

[0034] The zeolite of the present invention will be described in detail below using examples, but the present invention is not limited to these examples in any way.

[0035] Measurements and evaluations in the examples of the present invention were carried out by the following methods.

[0036] (composition analysis) The composition of the zeolite was analyzed using an X-ray fluorescence analyzer (Rigaku Corporation, product name "RIX-3000"). The Si and Al contents were converted to SiO2 and Al2O3, respectively, and the silica-alumina ratio (SiO2 / Al2O3 molar ratio) was calculated.

[0037] (Na content measurement) The sodium content was measured using an atomic absorption spectrophotometer (Hitachi, product name "Z-5300"). The sample was placed in a platinum crucible, and sulfuric acid and hydrofluoric acid were added. The sample was then heated and evaporated to dryness. Hydrochloric acid and water were then added, and the mixture was heated to dissolve. The diluted solution was then diluted with ion-exchanged water. The sodium concentration of this diluted solution was measured using the atomic absorption spectrophotometer. The sodium content of the sample was calculated in terms of Na2O from the results.

[0038] (X-ray diffraction measurement) An X-ray diffractometer (Rigaku Corporation, product name "RINT-2100", radiation source: CuKα) was used to measure the crystalline structure of zeolites. If peaks attributable to the diffraction planes of faujasite-type zeolite were confirmed in the X-ray diffraction pattern at 2θ = 5 to 50°, the zeolite was determined to be faujasite-type zeolite. Specifically, the presence or absence of peaks attributable to the (331), (511), (440), (533), (642), and (555) planes was confirmed. The positions of the peaks attributable to these diffraction planes can be confirmed from technical literature (MMJ Treacy, Jb Higgins, COLLECTION OF SIMULATED XRD POWDERPATTERNS FOR ZEOLITES, Fifth Revised Edition, Elsevier). The peak position may vary slightly depending on the measurement conditions, and so if it is within ±0.5° from the peak position described in the above document, it can be considered that the peak is derived from faujasite-type zeolite. From the X-ray diffraction pattern thus obtained, the intensities of the peaks assigned to the (331), (511), (440), (533), (642), and (555) planes of faujasite-type zeolite were summed. The peak intensities of the faujasite-type zeolite (JRC-Z-Y5.3) reference catalyst of the Catalysis Society, which were measured in the same manner, were summed up. The ratio of the intensity of the peaks relating to the faujasite-type zeolite obtained in the examples to the total intensity of these peaks was calculated to calculate the X-ray diffraction intensity ratio, which was taken as the crystallinity of the zeolite obtained in the examples.

[0039] (Lattice constant measurement) The lattice constants of zeolites were measured using an X-ray diffractometer (Rigaku Corporation, product name "RINT-2100"). Zeolite powder and TiO2 anatase powder (titanium(IV) oxide (anatase) manufactured by Kanto Chemical Co., Ltd.) as an internal standard were mixed in a mortar at a weight ratio of 2:1 to prepare a measurement sample. X-ray diffraction patterns were measured using CuKα radiation at 2θ = 23 to 33°, and the lattice constants were calculated from the following formulas (1) to (3) using 2θ, which indicates the center of the half-width of the peaks of the (533) and (642) planes of TiO2 anatase and faujasite zeolites.

[0040]

number

[0041] A: Center of half-width of peak showing (533) plane (2θ) [°] B: Center of half-width of peak representing (642) plane (2θ) [°] C: Center of half-width of peak (2θ) [°] shown by TiO2 anatase type

[0042] (Water adsorption evaluation) 1.0 g of zeolite powder was pretreated at 500°C for 1 hour, and then allowed to absorb moisture for 5 hours in a thermo-hygrostat (Tokyo Rikaki Co., Ltd., product name "KCL-2000") at 40°C and 40% humidity. The amount of water adsorption was calculated from the sample weight before and after moisture absorption as follows: Water adsorption amount (%) = [(sample weight after moisture absorption - sample weight before moisture absorption) / sample weight before moisture absorption] × 100

[0043] (Pyridine adsorption FT-IR measurement) 20 mg of zeolite powder was molded into a 20 mm diameter disk, placed in an IR cell connected to a vacuum line, and evacuated at 500 °C for one hour. After pretreatment, the temperature was lowered to 150 °C, and the IR spectra of the sample disk were measured using a Fourier transform infrared spectrophotometer (manufactured by JASCO Corporation, product name "FT / IR-4600") before and after the introduction of pyridine vapor. After pyridine was introduced, the IR spectrum of the sample disk was similarly measured after evacuation at 450 °C. Quantitation of Bronsted acid sites was performed based on technical literature (CA Emeis, J. Catal., 141, 347-354 (1993)).

[0044] (specific surface area measurement) The specific surface area of ​​zeolite was measured using an MR-6 analyzer manufactured by Nippon Bell Co., Ltd. Zeolite powder was pretreated for 1 hour at 500°C in an inert gas atmosphere. A mixed gas of 30 vol% nitrogen and 70 vol% helium was passed through the measurement sample cell at -196°C to adsorb nitrogen onto the zeolite powder. The ambient temperature was then raised to 25°C, allowing the nitrogen adsorbed on the zeolite powder to desorb. The amount of desorbed nitrogen was detected using a TCD (thermal conductivity) detector. The specific surface area per gram of zeolite powder was calculated by converting the detected amount of desorbed nitrogen into specific surface area using the cross-sectional area of ​​the nitrogen molecule.

[0045] [Example 1] A faujasite-type zeolite with a lattice constant of 2.439 nm, a water adsorption capacity of 19.5%, a crystallinity of 0.88, a silica-alumina ratio of 5.0, and a Na content of 1.10 mass% was prepared. 8.0 kg of this faujasite-type zeolite was suspended in 62 L of water at room temperature, and the molar amount of protons relative to the amount of Al contained in the faujasite-type zeolite (H + An acid solution was prepared by gradually adding 25% by mass of sulfuric acid so that the saturation ratio (S / Al) was 3.1, and the temperature was raised to 40°C, maintained at this temperature, and stirred for 4 hours. After stirring, the acid solution was filtered, and the obtained solid was washed with 96 L of ion-exchanged water at 60°C and further dried at 110°C for 20 hours. The zeolite obtained through this process was subjected to the above measurements and evaluations. The results are shown in Table 1.

[0046] [Example 2] A zeolite was obtained in the same manner as in Example 1, except that sulfuric acid was added so that the molar amount of protons relative to the amount of Al contained in the faujasite zeolite was 6.0. This zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0047] [Example 3] A zeolite was obtained in the same manner as in Example 1, except that sulfuric acid was added so that the molar amount of protons relative to the amount of Al contained in the faujasite zeolite was 7.2. This zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0048] [Comparative Example 1] A zeolite was obtained in the same manner as in Example 1, except that after preparing the acid solution, the temperature was raised to and maintained at 90°C, and sulfuric acid was added so that the molar amount of protons relative to the amount of Al contained in the faujasite zeolite was 4.6. The zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0049] Comparative Example 2 The molar amount of protons (H + A zeolite was obtained in the same manner as in Comparative Example 1, except that sulfuric acid was added so that the saturation ratio (S / Al) was 5.6. This zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0050] Comparative Example 3 The molar amount of protons (H + A zeolite was obtained in the same manner as in Example 1, except that sulfuric acid was added so that the saturation ratio (S / Al) was 1.6. The zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0051] Comparative Example 4 The molar amount of protons (H + A zeolite was obtained in the same manner as in Example 1, except that sulfuric acid was added so that the saturation ratio (S / Al) was 9.7. The zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0052] Comparative Example 5 The faujasite-type zeolite used had a lattice constant of 2.429 nm, a water adsorption capacity of 9.0%, a crystallinity of 0.85, a silica-alumina ratio of 5.0, and a Na content of 1.1 mass%. The molar amount of protons relative to the amount of Al contained in the faujasite-type zeolite (H + A zeolite was obtained in the same manner as in Example 1, except that sulfuric acid was added so that the saturation ratio (S / Al) was 4.6. The zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0053] Comparative Example 6 The faujasite-type zeolite used had a lattice constant of 2.442 nm, a water adsorption capacity of 24.4%, a crystallinity of 0.86, a silica-alumina ratio of 5.0, and a Na content of 1.1 mass%. The molar amount of protons relative to the amount of Al contained in the faujasite-type zeolite (H + A zeolite was obtained in the same manner as in Example 1, except that sulfuric acid was added so that the saturation ratio (S / Al) was 3.0. The zeolite was subjected to the same measurements and evaluations as in Example 1. The results are shown in Table 1.

[0054] [Table 1]

[0055] The zeolites obtained by acid treatment at high temperature (Comparative Examples 1 and 2) had a high ratio of Bronsted acids with high acid strength remaining after evacuation at 450°C, at 67%. H + The zeolite obtained by acid treatment under conditions of low H / Al (Comparative Example 3) had a high percentage of strong Bronsted acids remaining after evacuation at 450°C, at 65%. +The zeolite obtained by acid treatment under conditions of high / Al (Comparative Example 4) had a significantly reduced crystallinity, and the lattice constant could not be measured. In addition, the amount of Bronsted acid derived from the zeolite was also small. The zeolite obtained by acid treatment using a faujasite-type zeolite with a small lattice constant (Comparative Example 5) had a high proportion of strong Bronsted acids remaining at 66% after evacuation at 450°C. Furthermore, the zeolite obtained by acid treatment using a faujasite-type zeolite with a large lattice constant (Comparative Example 6) had a significantly reduced crystallinity, as in Comparative Example 4, and the lattice constant could not be measured. In contrast, the lattice constant of faujasite-type zeolite, the temperature of acid treatment, and H + The zeolites (Examples 1 to 3) obtained by acid treatment under conditions where the ratio of SiO2 to Al was within a specific range had a reduced degree of crystallinity while maintaining the faujasite framework structure, and the proportion of Bronsted acids with high acid strength remaining after evacuation at 450°C was low at 50% to 59%.

[0056] The zeolites of Example 1, Comparative Example 1, and Comparative Example 6 were subjected to a performance evaluation test under the following conditions. The results are shown in Table 2.

[0057] (Performance evaluation test) For the performance evaluation test of zeolite, a MAT (Micro Activity Test) device manufactured by Sakuragi Rikagaku Kikai Co., Ltd., designed in accordance with ASTM-D3907-80, was used. Before the performance evaluation test, the zeolite was calcined at 500°C for 1 hour. The operating conditions were as follows: Feedstock: Straight run diesel (LGO) Catalyst amount: 0.80g Oil flow amount / time: 1.60g / 90 seconds Catalyst / oil mass ratio (C / O): 0.50 Reaction temperature: 340℃ Conversion rate = 100 - heavy fraction yield Naphtha boiling point range: 20-145°C Kerosene boiling point range: 145-260°C Boiling range of heavy fraction: 260°C+

[0058] [Table 2]

[0059] According to Table 2, Example 1, in which the proportion of strong Bronsted acids remaining after exhaust at 450°C was 59%, exhibited a higher kerosene yield and a comparable conversion rate than Comparative Example 1, in which the proportion of strong Bronsted acids remaining after exhaust at 450°C was 67%. Comparative Example 6, in which the proportion of strong Bronsted acids remaining after exhaust at 450°C was 5%, exhibited a significantly lower conversion rate than Example 1 and Comparative Example 1. These results confirmed that by adjusting the proportion of strong Bronsted acids remaining in the zeolite after exhausting at 450°C to less than 65%, it is possible to improve the kerosene yield while maintaining a sufficient conversion rate, and also confirmed the usefulness of a catalyst containing the zeolite of the present invention, which has a low proportion of Bronsted acids with high acid strength. [Industrial Applicability]

[0060] The faujasite zeolite of the present invention can be suitably used as a catalyst for increasing the yield of middle distillates cracked with strong Bronsted acids in hydrocracking reactions. In addition, the faujasite zeolite of the present invention can be used as a fluidized bed catalyst or fixed bed catalyst in reactions that are adversely affected by strong Bronsted acids in the fields of petroleum refining and petrochemical industries, and is therefore industrially useful.

Claims

[Claim 1] SiO ２ / Al ２ O ３ The molar ratio of is in the range of 40 or more and 200 or less, The crystallinity is in the range of 0.20 or more and 1.00 or less, the Bronsted acid amount measured by pyridine adsorption FT-IR after evacuation at 150°C is in the range of 20 μmol / g or more and 400 μmol / g or less, The ratio of the Bronsted acid amount measured after evacuation at 450°C to the Bronsted acid amount measured after evacuation at 150°C is less than 65%. Faujasite-type zeolite.

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