CN1060098C - Hydrothermal treatment process of zeolite - Google Patents

Abstract

A method for hydrothermal treatment of zeolite, which comprises mixing zeolite with a sodium oxide content of less than 1% by weight, one or more forming aids selected from organic carbon-containing compounds with binding and lubricating functions, and water at a ratio of 100:1 ～15:50～140 weight ratio mixing, extrusion molding, and then at 500～870 ° C, the molded product is contacted with a water vapor-containing atmosphere with a water vapor weight space velocity of 0.05～3.5 hours ⁻¹ for 0.5～8 hours. Suitable for industrial production.

Description

A kind of hydrothermal treatment method of zeolite

The invention relates to a modification method of molecular sieves, more specifically to a hydrothermal treatment method of silica-alumina zeolite.

Catalysts with zeolite as the active component have been widely used in various hydrocarbon conversion reactions. The types and properties of zeolite used in the catalyst are also very different for different types of reactions. The selectivity of zeolite needs to be carried out various modification, and since US3,293,192, US3,402,996 discloses the method for treating Y-type zeolite with high-temperature steam to prepare ultra-stable Y, steam treatment zeolite has been It has become one of the most commonly used modification methods for zeolites. Zeolites modified by this method or other methods containing this method, such as faujasite, ZSM-5 zeolite, mordenite, Beta zeolite, etc., can be used as various hydrocarbons Active components of conversion catalysts, especially catalytic cracking and hydrocracking catalysts.

EP0,667,185A1 discloses a method for preparing modified Y zeolite, which method comprises (a) exchanging NaY zeolite with an ammonium salt solution, so that the _Na2O content in the zeolite is reduced to below 7% by weight; (b) The product obtained in (a) is contacted with an acidic aluminum-containing aqueous solution of pH 2 to 4, so that the zeolite contains, in terms of Al ₂ O ₃ , 0.5 to 6% by weight of exchanged aluminum; (c), separation and washing (b) The obtained product is calcined at 450-800° C. under a steam atmosphere for 15 minutes to 4 hours; (d) the zeolite obtained in (c) is treated with a phosphorus-containing compound to introduce 0.1 to 4 % phosphorus (calculated as P ₂ O ₅ ), the modified zeolite prepared by this method has higher selectivity of gasoline and light cycle oil, and reduces coke yield.

However, as pointed out in US 5,288,396, if the molecular sieve is hydrothermally treated before being mixed with the heat-resistant inorganic oxide and formed, the molecular sieve is powdery and the particles are very small (0.1-10 microns in diameter generally) ), when hydrothermal treatment is carried out in an inclined kiln rotary furnace, a large number of particles flow along the furnace wall or furnace core, and the water vapor is not uniformly distributed in the flow, which makes it difficult for molecular sieve particles to evenly contact with water vapor in the flow, some Molecular sieve particles were exposed to too much water vapor and removed too much framework aluminum, while other molecular sieve particles were exposed to little water vapor, and the framework aluminum was basically not removed, which led to the product after hydrothermal treatment of molecular sieve particles. The stability is not good. For example, the catalytic activity and/or selectivity of the molecular sieve products obtained in two experiments under the same conditions are very different, and the catalytic activity and/or selectivity of the molecular sieve particles in the same experiment are also very different. It is difficult to Well suited for industrial applications. Furthermore, if the molecular sieve powder is subjected to hydrothermal treatment in a fixed bed, too small molecular sieve particles will cause too high a pressure drop, so it cannot be applied in industry.

In the hydrocracking method disclosed in US 5,288,396, a hydrothermal modification method of zeolite is disclosed. The hydrocracking process comprises contacting a hydrocarbon feedstock with a catalyst in the presence of hydrocracking and external hydrogenation, the catalyst contains a zeolite with a unit cell size of 24.20 to 24.40A, and the preparation of the zeolite The method comprises: (a) extruding at least one refractory inorganic oxide and a cracking active crystalline aluminosilicate zeolite component having a unit cell size of 24.40 ~24.95 angstroms selected from the group consisting of Y zeolite, modified Y zeolite, X zeolite and modified X zeolite; The conditions are such that the unit cell size of the crystalline aluminosilicate zeolite shrinks to 24.20-24.40 Angstroms. For example, the roasting temperature is at least 500°C, usually 600-870°C, preferably 700-850°C, the total pressure is 7.5-3000Psia, preferably 15-1500Psia, and the common range of water vapor partial pressure is 200-150Psia, preferably 5. 0～35Psia. The diameter of the catalyst particles prepared by this method is at least 1/32 inch, which is much larger than the molecular sieve particles. Therefore, when the catalyst particles are hydrothermally treated in the rotary furnace, they can pass through the furnace body evenly, and each catalyst particle can contact approximately The same amount of steam, so the properties of the catalyst after steam treatment are uniform and repeatable, and the treatment method can also be carried out in a fixed bed. However, what is obtained by this method is only a hydrocracking catalyst composition instead of pure zeolite. In addition, the carrier non-molecular sieve component (ie, heat-resistant inorganic oxide) is simultaneously treated with high-temperature water vapor in this way. change its nature. In the laboratory, the method of first pressing the zeolite into tablets and then crushing it into particles, then sieving the zeolite with a suitable particle size, and finally performing steam treatment is used. This method can obtain pure molecular sieves, but the operation is complicated. When crushing and sieving to get a suitable particle size, the yield is very low, and this method obviously cannot be applied on a large scale in industry.

The purpose of the present invention is to provide a hydrothermal treatment method of zeolite which has uniform properties and good repeatability and is more suitable for industrial application on the basis of the prior art.

The method provided by the invention comprises mixing zeolite with a sodium oxide content of less than 1% by weight, one or more auxiliary molding agents selected from organic carbon-containing compounds with binding and lubricating functions, and water at a ratio of 100:1 to 15:50 to Mixing at a weight ratio of 140, extrusion molding, and then contacting the molded product with an atmosphere containing water vapor at a water vapor weight space velocity of 0.05 to 3.5 hours ⁻¹ at 500 to 870 ° C for 0.5 to 8 hours.

According to the method provided by the present invention, the zeolite can be any existing zeolite, such as natural or synthetic faujasite, ZSM series zeolite, mordenite, Beta zeolite, omega zeolite, etc., preferably X-type zeolite, Y-type Zeolite, mordenite or ZSM-5 zeolite, more preferably Y-type zeolite, mordenite or ZSM-5 zeolite, preferably Y-type zeolite, said zeolite may be a zeolite containing other desired components, such as rare earth-containing Rare earth type zeolite, zeolite containing alkaline earth metal, zeolite containing elements such as nickel, cobalt, iron, zinc, and aluminum type zeolite containing external aluminum, etc., the method provided by the invention is especially suitable for AlY zeolite containing external aluminum. Other components in the zeolite of other components (such as aluminum) can be introduced by conventional ion exchange method, impregnation method, or by mechanically mixing the salt of the ion or its aqueous solution which can be burned off by high temperature roasting and zeolite. , when the ions are aluminum ions, the introduction amount of aluminum ions (calculated as alumina) is not more than 20% by weight, preferably 0.05-10% by weight; the zeolite containing sodium oxide below 1% by weight can Sodium zeolite is obtained by ion exchange (such as ammonium ion exchange).

The auxiliary molding agent selected from organic carbon-containing compounds can be any organic carbon-containing compound that has bonding and lubricating effects and can be burned at high temperature, preferably one of methyl cellulose, polyvinyl alcohol, and vegetable starch. One or several kinds, the weight ratio of zeolite to auxiliary forming agent and water is preferably 100:2～10:60～120.

The temperature of the hydrothermal treatment is preferably 550-700° C.; the atmosphere containing water vapor can be a mixture of water vapor and air, a mixture of water vapor and oxygen, a mixture of water vapor and other inert gases such as nitrogen, or 100 °C. % water vapor, preferably a mixture of water vapor and air, which can ensure that most of the auxiliary molding agent is burned off after steam treatment. When the atmosphere containing water vapor is a mixture of water vapor and air, water vapor The weight space velocity is preferably 0.1 to 2.45 hours ^-1 , the volume space velocity of air can be 0.1 to 1500 hours ^-1 , preferably 1 to 1200 hours ^-1 ; the zeolite particles and the water vapor atmosphere The contact time is preferably 2 to 6 hours. When the steam-containing atmosphere does not contain air or oxygen, part of the auxiliary forming agent remains in the processed molded product. At this time, the auxiliary forming agent can be removed by roasting under the air atmosphere.

According to the method provided by the present invention, the zeolite, the auxiliary forming agent and water are firstly mixed uniformly, extruded and formed, and then the formed product is subjected to hydrothermal treatment, and the radial mechanical strength of the formed product before the hydrothermal treatment is not less than 6.0 kg/cm , the radial strength after hydrothermal treatment is not more than 10 kg/cm. On the one hand, the molded product with such strength ensures that the molded product is not easy to be crushed or broken during the hydrothermal treatment process, and on the other hand, it ensures that the zeolite is easy to grind after the hydrothermal treatment. It is convenient for the preparation of the zeolite-containing catalyst, so it is more suitable for the needs of industrial production.

Theoretically, in the method provided by the present invention, the particle size of the zeolite molding can be adjusted according to the activation furnace used and the specific experimental conditions. If it is used in a fixed bed activation furnace, the particle size of the zeolite needs to be adjusted to be larger to reduce the bed size. The layer pressure drop will not cause channeling and other phenomena at the same time. When used in a rotary kiln, the particle size of the molded product can be determined according to the air velocity or other reaction conditions. According to the method of US 5,288,396, it is necessary to take into account the catalyst in the reaction. It is difficult to match the particle size in the medium with the particle size of the hydrothermal treatment. Furthermore and US 5,288, the same reason as stated in 396, the zeolite obtained by the method provided by the present invention has uniform properties and good repeatability.

The zeolite treated with the method provided by the invention can be widely used as active components of various hydrocarbon conversion catalysts such as catalytic cracking catalysts, hydrotreating catalysts, hydrocracking catalysts, alkylation catalysts, and isomerization catalysts, and is especially suitable for Used as an active component of hydroprocessing and hydrocracking catalysts, for example, the unit cell constant of Y-type zeolite or AlY zeolite treated according to the method provided by the present invention can shrink from 24.56A to less than 24.43A, The secondary porosity is greater than or equal to 24.5%, and the hydrocracking catalyst containing this zeolite has higher cracking activity while maintaining similar isomerization selectivity compared with the prior art industrial catalyst, such as using n-heptane As the reaction raw material, under the reaction conditions of 350° C. of reaction humidity, 2.5 MPa of hydrogen pressure, and ¹ hour of volume space velocity, when using the zeolite hydrotreating catalyst prepared by the method containing 5% by weight, when maintaining and existing While the technical catalyst has similar isomerization selectivity, the conversion rate of n-heptane is increased to 35.06-45.18% by weight, while the conversion rate of n-heptane is only 20.49% by weight when using the prior art catalyst.

The following examples will further illustrate the present invention.

Example 1

According to the method provided by the invention, the Y-type zeolite is subjected to hydrothermal treatment.

Put 800 grams of NaY zeolite (SiO ₂ /Al ₂ O ₃ =3.5, product of Changling Refinery Catalyst Factory) into 4000 ml of ammonium chloride (analytically pure, product of Beijing Chemical Plant) aqueous solution with a concentration of 1.0M , exchanged at 90°C for 1 hour, filtered, washed with deionized water until no chloride ions were detected, dried at 120°C, roasted at 550°C for 4 hours, and repeated the above process twice to obtain a sodium oxide content of 0.35% by weight (Determined by flame atomic absorption spectrometry) Y-type zeolite A', the unit cell constant of the zeolite measured by X-ray diffraction method is 24.56A, and the relative crystallinity is determined as 100%.

100 grams of Y-type zeolite A' after the above-mentioned ammonium exchange, 70 milliliters of deionized water and methyl cellulose (brand M20, produced by Shanghai Chemical Reagent Factory,) are mixed uniformly, and extruded into a strip with a diameter of 3 mm on the extruder After drying, its radial strength was measured to be 10.0 kg/cm. The dried molded product was placed in a vertical activation furnace, and water and air were introduced at a rate of 250 g/h and 1 liter/h respectively, and the temperature was raised to 650 °C. ℃ and kept at constant temperature for 2 hours, after cooling, the treated Y-type zeolite A was obtained, and its physical and chemical properties are listed in Table 1. Among them, the radial strength determination method is referred to "Petrochemical Analysis Method" (RIPP test method) P66-67, Science Press, 1990, unit cell constant, relative crystallinity, skeleton silicon-aluminum ratio are measured by X-ray diffraction method, micropore volume 1. The pore volume is determined by the low-temperature nitrogen adsorption BET method, and the secondary porosity = (pore volume-micropore volume)/pore volume×100%.

Example 2

According to the method provided by the invention, the AlY type zeolite is subjected to hydrothermal treatment.

Take aluminum nitrate (chemically pure, Beijing chemical plant product) 11 grams and be dissolved in 65 milliliters of deionized waters and be made into aluminum nitrate solution, this solution and the zeolite A '100 grams that example 1 prepares and methyl cellulose 3.0 grams Mix evenly, extrude into strips with a diameter of 3 mm on the extruder, measure the radial strength after drying to be 12.0 kg/cm, place the dried moldings in a vertical activation furnace, and heat them at 200 g/h And 0.5 liters/hour speed pass into deionized water and air, heat up to 600 ℃ and keep the temperature for 4 hours, after cooling, the treated AlY zeolite B is obtained, and its physical and chemical properties are listed in Table 1.

Example 3

According to the method provided by the invention, the AlY type zeolite is subjected to hydrothermal treatment.

Take by weighing 31 grams of aluminum nitrate (same as example 2) and be dissolved in 70 milliliters of deionized water to make aluminum nitrate solution, and this solution is mixed with 100 grams of zeolite A' 100 grams prepared by example 1 and 3 grams of fennel powder (produced by Shanghai Native Product Company) Evenly, extrude into strips with a diameter of 3 mm on the extruder, measure its radial strength after drying to be 10 kg/cm, place the dried moldings in a vertical activation furnace, and heat them at 150 g/h and 5 liters respectively Pass deionized water and air at a rate of 1 hour, heat up to 550° C. and keep the temperature constant for 6 hours. After cooling, the treated AlY zeolite C is obtained, and its physical and chemical properties are listed in Table 1.

Example 4 According to the method provided by the present invention, AlY type zeolite was subjected to hydrothermal treatment.

Take by weighing aluminum nitrate (with example 2) 77 grams and be dissolved in 100 milliliters of deionized waters and be made into aluminum nitrate solution, zeolite A ' 100 grams and 3 grams of asparagus powder of this solution and example 1 preparation, polyhexenol (chemical Pure, produced by Shanghai Petrochemical General Plant) 5 grams are mixed evenly, extruded into strips with a diameter of 3 mm on the extruder, and the radial strength is measured as 15 kg/cm after drying, and the dried molding is placed in a vertical activation In the furnace, deionized water and air were introduced at a rate of 10 g/h and 110 liter/h respectively, and the temperature was raised to 650°C and kept at a constant temperature for 4 hours. After cooling, the treated AlY zeolite D was obtained, and its physical and chemical properties are listed in Table 1. middle.

Example 5

According to the method provided by the invention, the mordenite containing external aluminum is subjected to hydrothermal treatment.

Weigh 11 grams of aluminum nitrate and dissolve it in 112 milliliters of deionized water to form an aluminum nitrate solution, mix the solution with mordenite (SiO ₂ /Al ₂ O ₃ =20, sodium oxide content: 0.01% by weight, Fushun Petrochemical Co., Ltd. factory) 150 grams, 3 grams of tianqing powder and 3 grams of methyl cellulose are mixed evenly, extruded into strips with a diameter of 3 mm on the extruder, and the radial strength is measured to be 17 kg/cm after drying. The molded product is placed in a vertical activation furnace, water and air are introduced at a rate of 70 g/h and 10 liters/h respectively, the temperature is raised to 550 ° C and kept at a constant temperature for 4 hours, and after cooling, the treated mordenite E is obtained. Its physical and chemical properties Listed in Table 1.

Example 6

According to the method provided by the invention, ZSM-5 is subjected to hydrothermal treatment.

150 grams of ZSM-5 zeolite (SiO ₂ /Al ₂ O ₃ =40, sodium oxide content: 0.1% by weight, produced by Shanghai No. The base cellulose is mixed evenly, extruded into strips with a diameter of 3 mm on the extruder, and its radial strength measured after drying is 13 kg/cm. hours and 7.5 liters/hour speed into deionized water and air, heated to 550 ° C and kept at a constant temperature for 4 hours, after cooling, the treated ZSM-5 zeolite F was obtained, and its physical and chemical properties are listed in Table 1.

Table 1 instance number 1 2 3 4 5 6 Zeolite product number A B C D. E. f Radial mechanical strength, kg/cm 2.0 3.0 5.0 6.0 2.5 4.0 Unit cell constant, Angstroms 24.43 24.39 24.36 24.32 - - Relative crystallinity, % 95 78 64 54 93 96 Skeleton Si-Al Ratio, mol/mol 7.4 8.9 9.5 11.8 - - Pore volume, ml/g 0.2345 0.2450 0.2080 0.2220 - - Pore volume, ml/g 0.3120 0.3500 0.2870 0.3300 - - Secondary porosity, % 24.8 30.0 27.5 32.7 - -

Example 7~8

The following examples illustrate the catalytic performance of hydroprocessing catalysts containing zeolites prepared by the process of the present invention.

The AlY zeolite and mordenite prepared by example 2 and example 5 are mixed with SB powder (containing 85% by weight of pseudo-boehmite, produced by Germany Condea Company) in a weight ratio of 5:95 (dry basis), and an appropriate amount of auxiliary agent is added. Squeeze agent and water, extrude strips with a diameter of 2 mm on the extruder, dry at 120 ° C, and roast at 600 ° C for 4 hours to obtain a catalyst carrier containing AlY and mordenite. Weigh the carrier containing AlY zeolite and the carrier containing mordenite 100 grams each of the carrier, impregnated with 65 grams of NH ₄ F (chemically pure, produced by Beijing Chemical Factory) solution with a concentration of 23.1% by weight, dried at 120°C, and then filled with WO ₃ 638.5 grams per liter Ammonium metatungstate (NH ₄ W ₄ O ₃ 18H ₂ O, chemically pure, produced by Sichuan Zigong Cemented Carbide Factory) and NiO 63.85 g/L and nickel nitrate (Ni(NO ₃ ) ₂ 6H ₂ O , chemically pure, Beijing Chemical Plant) solution 65 ml impregnation, 120 ° C drying, 500 ° C roasting for 4 hours, to obtain AlY zeolite-containing catalyst I and mordenite-containing catalyst II, the catalyst contains 5% by weight of fluorine, NiO2. 7% by weight, WO ₃ 27.0% by weight (calculated value).

Catalysts II and II were broken into 40-60 mesh particles respectively, and mixed with quartz sand of equal particle size at a volume ratio of 1:1, and loaded into a 2 ml reactor, using n-heptane as a model compound for catalysts I and II The catalytic performances of the catalysts were evaluated respectively. Before the evaluation, the catalyst was presulfided with n-heptane containing 3% carbon disulfide for 2 hours under a hydrogen atmosphere at 300 ° C. The evaluation conditions were reaction temperature 350 ° C, hydrogen pressure 2.5 MPa, volume empty Speed 1 hour ^-1 , hydrogen flow rate 400 milliliters/minute, reaction product is analyzed by gas chromatography, n-heptane conversion rate and isomerization selectivity are listed in table 2, here, isomerization selectivity=isomeric product yield/ Conversion x 100%.

Comparative example 1

This comparative example shows that the zeolite catalyst prepared by the method provided by the present invention has higher catalytic activity while maintaining high isomerization selectivity compared with existing industrial catalysts.

Under the same conditions as examples 7-8, industrial catalyst III (RL-1, produced by Changling Refinery, alumina carrier, fluorine-containing 4.9% by weight, NiO 2.9% by weight, WO ₃ 28.3% by weight %) for evaluation, the conversion and isomerization selectivity of n-heptane are listed in Table 2. Table 2 instance number 7 8 Comparative example 1 Catalyst number I II III Conversion rate,% 45.18 35.06 20.49 Isomerization selectivity, % 92.0 91.0 92.0

Claims (9)

1. A hydrothermal treatment method for zeolite, which is characterized in that the method comprises zeolite with a sodium oxide content of less than 1% by weight, one or more forming aids selected from organic carbon-containing compounds with binding and lubricating effects, and water Mix at a weight ratio of 100:1~15:50~140, extrude, and then contact the molded product with an atmosphere containing water vapor at a water vapor weight space velocity of 0.05~3.5 hours ^-1 at 500~870°C 0.5 to 8 hours. 2. The method according to claim 1, characterized in that the zeolite refers to Y-type zeolite, mordenite or ZSM-5 zeolite. 3. The method according to claim 2, characterized in that said zeolite refers to Y-type zeolite. 4. The method according to claim 3, characterized in that said zeolite refers to AlY zeolite containing externally added aluminum. 5. The method according to claim 4, characterized in that, based on Al ₂ O ₃ , the amount of aluminum introduced into the AlY zeolite is no more than 20% by weight. 6. The method according to claim 5, characterized in that the amount of aluminum introduced into the AlY zeolite is 0.05-10% by weight. 7. The method according to claim 1, wherein the forming aid is selected from one or more of methyl cellulose, polyvinyl alcohol and vegetable starch, and the weight ratio of zeolite to forming aid and water is 100:2 ~10:60~120. 8. The method according to any one of claims 1-7, characterized in that the water vapor-containing atmosphere refers to a mixture of water vapor and air, and the volumetric space velocity of the air is 0.1-1500 hr ^-1 . 9. The method according to claim 8, characterized in that the water vapor weight space velocity is 0.1 to 2.45 hours ^-1 , the air volume space velocity is 1 to 1200 hours ^-1 , the mixed gas containing water vapor and air and zeolite The contact time of the molding is 2 to 6 hours.