A method for preparing mesoporous molecular sieves without ammonium

Abstract

The present invention provides a method for preparing a mesoporous molecular sieve by an ammonium-free method, comprising the following steps: placing an organic polymer in an alkaline solution for depolymerization, then adding a molecular sieve and a soluble modified metal compound, stirring evenly and then calcining, and subjecting the calcined product to an isomorphous substitution reaction with a halogen-containing gas, and then washing with water to obtain a molecular sieve containing mesopores. The method of the present invention has a simple preparation process, and achieves the purpose of molecular sieve without ammonium exchange and having a large number of mesopores.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve preparation, and specifically relates to a method for preparing a mesoporous molecular sieve by an ammonium-free method. Background Art

[0002] Catalytic cracking is a parallel sequential reaction. A rich and developed pore structure is one of the important directions for catalyst design. The catalyst has developed pores, which can not only enhance the mass transfer and diffusion performance and improve the catalytic efficiency, but also make it easy to remove hydrocarbons between particles during stripping in the catalytic cracking unit, greatly reducing the amount of hydrocarbons entrained by the catalyst into the regenerator, which is conducive to the recovery of catalyst activity after regeneration and improving the actual operating activity and selectivity of the unit. Therefore, the development of FCC catalysts with developed pore structures and high molecular sieve stability has always been the focus of research in various research institutions.

[0003] In terms of improving and constructing the mesoporous pore structure of molecular sieves, soft and hard template methods and post-treatment methods are usually used to achieve this. CN201710373424.6 introduces a method for producing alumina and SBA-15 mesoporous molecular sieves from fly ash, CN202011129576.X discloses a method for growing mesoporous molecular sieves on the surface of microporous molecular sieves, and CN201810945900.1 adds ultraviolet light and hydrogen peroxide synthesis during the preparation of mesoporous molecular sieves to improve acidity; CN201810959715.8 provides a method for preparing mesoporous molecular sieves, in which ultraviolet light and sodium persulfate are added during the preparation of mesoporous molecular sieves to improve the acidity of the mesoporous molecular sieves. CN201910143399.1 describes in detail a method for preparing mesoporous molecular sieves by direct hydrothermal method without mesoporous template in a system where mesoporous silica is a silicon source precursor. CN202011201229.3 synthesizes mesoporous molecular sieves by adding quaternary ammonium salts; CN201410083041.1 discloses the use of molecular sieve precursor assembly and seeding methods to obtain highly stable mesoporous molecular sieves. CN201310147769.1 introduces a method for preparing a mesoporous Y-type molecular sieve, which is treated with organic acid and alkali, and then treated with ammonium nitrate. CN1388064A discloses a method for preparing a Y-type molecular sieve with a unit cell constant of 24.20 to 24.40 angstroms, which method subjects NaY molecular sieves or Y-type molecular sieves that have been subjected to ultra-stabilization treatment to one or more ammonium exchanges, hydrothermal treatments and / or chemical dealumination to form pores. CN1803612A adds a surfactant during the acid dealumination process to reduce the degree of damage to the molecular sieve. CN104229823A discloses a modification method for obtaining a mesoporous ultrastable Y molecular sieve by simultaneously adding an organic acid and an inorganic salt dealumination agent during the modification process to carry out organic acid-inorganic salt combined modification.

[0004] Through the analysis of relevant patents on the preparation of mesoporous molecular sieves, for molecular sieves in catalytic cracking catalysts, soft templates have the disadvantage of environmental problems caused by the subsequent calcination and removal of organic matter. The hard template method uses carbon powder or other inorganic materials to adjust the pore structure by controlling the appropriate amount of addition, but there are disadvantages such as disordered pore structure, difficult to control pore volume, and difficult to control catalyst strength. The post-treatment method has a long process flow, complex preparation, and difficulty in treating the wastewater generated, which is not conducive to industrial implementation. In order to obtain a Y-type molecular sieve with a very small unit cell constant and a large pore volume, deep dealumination is often used, which causes serious damage to the molecular sieve skeleton, and it is difficult to obtain a molecular sieve product with good crystallinity and a high silicon-aluminum ratio. In addition, the introduction of ammonium salt exchange also brings about prominent ammonia nitrogen pollution problems. In order to solve the problem of exchanging molecular sieves without ammonium, CN202010059891.3 discloses a method for preparing mesoporous molecular sieves without ammonia, in which the molecular sieve raw material is contacted with a dealuminizing pore-forming agent in water for chemical dealuminizing pore-forming treatment without ammonium exchange to obtain a secondary mesoporous molecular sieve product. Although this method can prepare a certain amount of mesopores, it is difficult to implement in industry; CN201711117556.9 introduces in detail the method of contacting NaY molecular sieve raw powder with chlorine-containing gas for gas phase ion exchange reaction, completing the sodium reduction and ultra-stabilization of NaY molecular sieve raw powder in one step, and preparing a low-sodium high silicon-aluminum ratio molecular sieve. CN201711074372.9, CN201611117946.1, and CN1286721C all report the use of gas phase ultra-stabilization to achieve ammonium-free exchange. Patent CN101850239A manufactures molecular sieve into molecular sieve paper, then heat presses the molecular sieve paper into a corrugated shape, alternately stacks or rolls it with molecular sieve paper to form a honeycomb, places it in a sealed container, and reacts with a mixed gas of nitrogen and silicon tetrachloride gas. After the reaction is completed, the molecular sieve honeycomb is repeatedly cleaned and then washed with acid. The product obtained by this method has uniform properties and avoids the problem of molecular sieves sticking together. However, in order to manufacture molecular sieve paper and honeycomb, if a powder product is to be obtained, the honeycomb needs to be broken, which increases the manufacturing cost and labor intensity. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing mesoporous molecular sieves by an ammonium-free method, so as to solve the problems of long process flow, high wastewater volume, reduced quality of molecular sieves, and few mesopores in the prior art.

[0006] To achieve the above object, the present invention provides a method for preparing mesoporous molecular sieves by an ammonium-free method, comprising the following steps:

[0007] The organic polymer is placed in an alkaline solution for depolymerization, and then a molecular sieve and a soluble modified metal compound are added, stirred evenly and then calcined, the calcined product is subjected to an isomorphous substitution reaction with a halogen-containing gas, and then washed with water to obtain a molecular sieve containing mesopores.

[0008] In the method for preparing mesoporous molecular sieves by an ammonium-free process described in the present invention, the modified metal compound is one or more of a zinc salt, an alkaline earth metal salt and a rare earth metal compound, the zinc salt is zinc chloride and / or zinc nitrate, the alkaline earth metal salt is one or more of a chloride, a nitrate, a chlorate and an acetate, and the rare earth metal compound is one or more of a rare earth chloride, a rare earth nitrate and a rare earth hydroxide.

[0009] The type of alkaline earth metal is not specifically limited, and is preferably one or more of chlorides, nitrates, chlorates and acetates mainly composed of magnesium (Mg) and calcium (Ca), the rare earth elements are one or more of rare earth chlorides, rare earth nitrates, rare earth carbonates and rare earth hydroxides mainly composed of lanthanum, cerium, yttrium, etc., and the molecular sieve is one or more of Y, ZSM-5, type A, mercerized, ZSM-11.

[0010] In the method for preparing mesoporous molecular sieve by the ammonium-free method of the present invention, the organic polymer is one or more of anionic, cationic or neutral polyacrylamide, carboxymethyl cellulose, methyl cellulose, cellulose and starch.

[0011] In the method for preparing mesoporous molecular sieves by the ammonium-free method of the present invention, the depolymerization temperature is 60 to 120° C., preferably 70 to 100° C., and the depolymerization time is 0.5 to 6 hours, preferably 1 to 4 hours.

[0012] The alkaline solution used in the depolymerization process can be ammonia water, sodium hydroxide solution, potassium hydroxide solution, etc., preferably ammonia water. In the aqueous solution of alkaline substances, the side chains of the polymer can be unfolded and extended. Those skilled in the art can determine the amount of the organic polymer and the alkaline solution according to the liquid-to-solid ratio, temperature and time of mixing. As long as the side chains of the organic polymer are fully unfolded and extended, there is no special limitation. Preferably, if ammonia water with a concentration of 5-28% is selected as the alkaline solution, the liquid-to-solid ratio of ammonia water to the organic polymer is 1:1.5-10.

[0013] In the ammonium-free method for preparing mesoporous molecular sieves of the present invention, the organic polymer is added in an amount of 1-20% of the molecular sieve mass; the modified metal compound is added in an amount of 0.1-10% of the molecular sieve mass.

[0014] In the method for preparing mesoporous molecular sieve by the ammonium-free method of the present invention, the calcination is performed by spray flash drying at 500 to 850° C. for 30 to 240 minutes.

[0015] In the method for preparing mesoporous molecular sieve by the ammonium-free method of the present invention, the halogen-containing gas is one or more of phosphorus trichloride, phosphorus pentachloride, phosphorus trifluoride, phosphorus pentafluoride, monochloramine, dichloramine and trichloramine.

[0016] In the ammonium-free method for preparing mesoporous molecular sieves of the present invention, the mass ratio of the halogen-containing gas to the calcined product is 0.01-0.8:1, preferably 0.05-0.4:1, the temperature of the isomorphous substitution reaction is 200-900° C., and the contact reaction time is 0.1-60 min.

[0017] The method for preparing mesoporous molecular sieves by an ammonium-free method of the present invention comprises the following steps: in the water washing step, washing is performed with distilled water, the mass ratio of the molecular sieve to H2O is 1:1-25, the pH value of the formed molecular sieve slurry is 2.5-8.5, the washing temperature is 30-95°C, and the washing time is 0.5-2h.

[0018] The ammonium-free method for preparing mesoporous molecular sieves of the present invention carries out isomorphous substitution reaction in a down-flowing bed isomorphous substitution reactor, the calcined product is added to the upper part of the reactor, and the halogen-containing gas is added from the lower part of the reactor for countercurrent contact.

[0019] The isomorphous substitution reactor of the present invention is a down-flow bed reactor, comprising a reaction chamber, a heating jacket is arranged outside the reaction chamber, the upper part of the reaction chamber is a buffer zone, the lower part is a reaction zone, a feeding device is arranged on the top of the buffer zone, and an atomizer is arranged in the feeding device.

[0020] The calcined product is added to the upper part of the isomorphous substitution reactor. Specifically, it can be transported to the sample inlet of the isomorphous substitution reactor feeding device by a lifting conveyor, and then enters the atomizer, sprayed into the reactor through the atomizer, and passes through the buffer zone and the reactor from top to bottom, and countercurrently contacts with the halogen-containing gas introduced from the bottom of the isomorphous substitution reactor. The atomizer is made of stainless steel, contains 20 symmetrically distributed air eyes, the diameter of the air eyes is 80-200 μm, and the gas pressure is 0.1-6 MPa. The effect of the reaction in the reaction zone and the buffer zone is controlled by the change of the internal diameter of the reactor and the gas flow rate. The diameter of the reaction cavity of the reactor is 0.05-0.5 meters, and the height is 0.2-2 meters. Preferably, the diameter of the buffer zone gradually decreases from top to bottom, the reaction zone is straight, the bottom end of the buffer zone is the same as the top end of the reaction zone, the ratio of the inner diameter of the top end of the buffer zone to the inner diameter of the reaction zone is 1:1-4:1, preferably 1:1-3:1, and the height of the buffer zone and the reaction zone is 0.1-1 meters respectively. The halogen-containing gas is carried into the reactor by a carrier gas, the carrier gas can be nitrogen, and the volume ratio of the halogen-containing gas to the carrier gas is 0.1-100%. The gas after the reaction enters the recovery system and is neutralized and collected by an alkaline solution in the recovery system, the alkaline solution can be a sodium hydroxide solution, a sodium carbonate solution, a sodium bicarbonate solution, etc., and the concentration can be 1-20wt%. The isomorphous substitution reactor heats the reaction chamber by a jacket electric heating method or a heating belt heating method.

[0021] The beneficial effects of the present invention are:

[0022] 1. First, the organic high molecular polymer is treated with an alkaline solution. The side chains of the treated organic high molecular polymer are unfolded and extended to form a chain network structure, thereby fixing the modified elements and ensuring that the modified elements are not lost.

[0023] 2. The addition of modified organic high molecular polymer can change the fluidization distribution state of the molecular sieve, so that the molecular sieve forms a stable fluidization state, the amount of dust is reduced, and thus the reaction efficiency of isomorphous substitution is improved.

[0024] 3. The addition of modified metal elements, on the one hand, provides the necessary modified elements for the Y-type molecular sieve; on the other hand, the introduction of these elements can migrate into the crystal structure of the Y-type molecular sieve, stabilize the structure of the molecular sieve, and lay the foundation for isomorphous substitution reaction.

[0025] 4. A down-going bed isomorphous substitution reactor is used to contact the molecular sieve with a halogen gas in countercurrent to carry out an isomorphous substitution reaction. Halogen gases such as phosphorus trichloride not only play an isomorphous substitution role, but also have a dealumination effect, so that the molecular sieve has more mesopores. Through the implementation of the above technology, the purpose of molecular sieve without ammonium exchange and having a large number of mesopores is achieved. This contact mode can not only effectively overcome the problems of catalyst back mixing and uneven radial distribution of catalyst particles caused by the reverse gravity operation of the upward riser, but also realize ultra-short contact operation of materials and reactants due to the increase in the gas-solid two-phase flow rate, and the reaction is uniform, so the excellent reaction effect is very outstanding, which is very suitable for gas and solid phase rapid processing reaction process.

[0026] 5. The isomorphous substitution reaction greatly improves the efficiency of reducing sodium oxide, without the need for ammonium salt exchange, and no ammonia nitrogen is produced during the modification process. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic structural diagram of the isomorphous substitution reactor of the present invention.

[0028] Wherein, the reference numerals are:

[0029] 1. Buffer zone;

[0030] 2. Reaction zone;

[0031] 3. Sample inlet;

[0032] 4. Atomizer;

[0033] 5. Gas inlet;

[0034] 6. Discharge port;

[0035] 7. Heating jacket. DETAILED DESCRIPTION

[0036] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0037] Figure 1 The schematic diagram of the structure of the down-bed isomorphous substitution reactor used in the present invention includes a reaction chamber, a heating jacket 7 is arranged outside the reaction chamber, a buffer zone 1 is arranged at the top of the reaction chamber, a reaction zone 2 is arranged at the bottom, a feeding device is arranged at the top of the buffer zone 1, and an atomizer 4 is arranged inside the feeding device.

[0038] The calcined product is transported to the sample inlet 3 of the isomorphous substitution reactor feeding device, and then enters the atomizer 4, sprayed into the reactor through the atomizer 4, passes through the buffer zone 1 and the reaction zone 2 from top to bottom, and countercurrently contacts with the halogen-containing gas introduced from the gas inlet 5 at the bottom of the isomorphous substitution reactor. In one embodiment of the present invention, the atomizer 4 is made of stainless steel, contains 20 symmetrically distributed gas eyes, the diameter of the gas eyes is 80 to 200 μm, and the gas pressure is 0.1 to 6 MPa.

[0039] The desired effect of the reaction of the reaction zone 2 and the buffer zone 1 is controlled by the change of the internal diameter of the reactor and the gas flow rate. In one embodiment of the present invention, the diameter of the reaction chamber of the reactor is 0.05 to 0.5 meters, and the height is 0.2 to 2 meters. In a preferred embodiment, the diameter of the buffer zone gradually decreases from top to bottom, the reaction zone is a straight cylinder, the bottom end of the buffer zone has the same diameter as the top end of the reaction zone, the ratio of the inner diameter of the top end of the buffer zone 1 to the inner diameter of the reaction zone 2 is 1:1 to 4:1, preferably 1:1 to 3:1, and the heights of the buffer zone 1 and the reaction zone 2 are 0.1 to 1 meter, respectively.

[0040] The halogen-containing gas is carried into the reactor by a carrier gas. In one embodiment of the present invention, the carrier gas can be nitrogen, and the volume ratio of the halogen-containing gas to the carrier gas is 0.1-100%. The gas after the reaction enters the recovery system and is neutralized and collected by an alkaline solution in the recovery system. In one embodiment of the present invention, the alkaline solution can be a sodium hydroxide solution, a sodium carbonate solution, a sodium bicarbonate solution, etc., and the concentration can be 1-20wt%. The isomorphous substitution reactor heats the reaction chamber by a jacket electric heating method or a heating belt heating method.

[0041] The present invention is explained below by way of examples.

[0042] Source of raw materials:

[0043] 1) Ammonia, chemically pure, Longyao Group

[0044] 2) Carboxymethyl cellulose, analytical grade, 100g (Shanghai test)

[0045] 5) Methyl cellulose, analytical grade, 100 g (Shanghai test)

[0046] 6) Starch, analytical grade, 100g (Shanghai test)

[0047] 7) Polyacrylamide, analytical grade, 100 g (Shanghai test)

[0048] 7) Molecular sieve: industrial product NaY, collected from Lanzhou Petrochemical Company Catalyst Plant (C / C0: 89%)

[0049] 8) Halogen gas: analytical grade, 250ml (Aladdin)

[0050] Specific analysis method:

[0051] The crystallinity of the Y-type molecular sieve was tested on a D / max-3C X-ray powder diffractometer manufactured by Rigaku, Japan, using the X-ray diffraction method to determine the crystallinity and silicon-aluminum ratio of the sample. The sample pore distribution test was conducted using the Autosorb-3B specific surface measuring instrument of Quantachrome, USA, and the specific surface area, pore size distribution and pore volume of the sample were determined by the N2 low temperature (77.3K) adsorption-desorption experimental method.

[0052] Example 1

[0053] Weigh 20 grams of cationic polyacrylamide and add it to a 28% ammonia solution with a liquid-to-solid ratio of 10. After treating at 60°C for 6 hours, add 100 grams of molecular sieve and 10 grams of zinc chloride. After stirring for 60 minutes, enter the spray flash drying device and roast at 850°C for 30 minutes. Add the roasted molecular sieve to the upper part of the isomorphous substitution reactor and slowly add it to the top of the downward bed reactor through the feeder. The top of the reactor is an atomizer with a gas eye diameter of 200μm and a pressure of 6MPa. After spraying by the atomizer, it runs downward and meets phosphorus trichloride gas. The volume ratio of phosphorus trichloride to nitrogen is 100:1. The reaction temperature is 900°C. The contact time with the gas is 0.1min. Control the gas flow rate to ensure that the mass ratio of phosphorus trichloride to molecular sieve is 0.5:1. The inner diameter of the buffer zone and the reaction zone are both 0.05 meters, and the heights are 0.2 and 0.3 meters respectively. After the reacted material enters the absorption tower for 30 minutes of purging, the reacted gas is discharged through the gas outlet pipe by pumping and enters the recovery system. The recovery system is a 10wt% sodium hydroxide solution, which neutralizes and collects the reacted gas. After the molecular sieve is collected by the collector at the bottom of the absorption tower, it is first washed with water. The molecular sieve washed with water: H2O=1:25, pH value is 8.5, washing temperature is 30℃, and washing time is 0.5h. The product after washing is washed and dried to become Y1.

[0054] Example 2

[0055] Weigh 6 grams of anionic polyacrylamide and add it to a 5% ammonia solution with a liquid-solid ratio of 1.5. After treating at 70°C for 0.5h, add 200 grams of molecular sieve and 4 grams of magnesium nitrate. After stirring for 120 minutes, enter the spray flash drying device and roast at 500°C for 200 minutes. Slowly add 150 grams of the roasted molecular sieve to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 50μm and a pressure of 0.1MPa. After spraying by the atomizer, the molecular sieve runs downward and meets phosphorus trifluoride gas. The volume ratio of phosphorus trifluoride to nitrogen is 0.1:1. The gas-solid phase reaction temperature is 200°C, and the contact time with the gas is 3min. Control the gas flow rate to ensure that the mass ratio of phosphorus trifluoride to molecular sieve is 0.01:1. The inner diameters of the buffer zone and the reaction zone are 0.5 meters and 0.125 meters respectively, and the height is 1 meter. The reacted material is purged in the absorption tower for 15 minutes. The gas is pumped out through the gas outlet pipe and enters the recovery system. The recovery system is a 20wt% sodium carbonate solution, which neutralizes and collects the gas after the reaction. The molecular sieve is collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water is: H2O=1:20, pH value is 6.5, washing temperature is 50℃, and washing time is 1h. The washed product is recorded as Y2.

[0056] Example 3

[0057] Weigh 15 grams of methyl cellulose and add it to a 10% ammonia solution with a liquid-solid ratio of 6. After treating at 120°C for 3 hours, add 150 grams of molecular sieve and 3 grams of magnesium chloride. After stirring for 100 minutes, enter the spray flash drying device and roast at 700°C for 240 minutes. Slowly add 100 grams of the roasted molecular sieve to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 80μm and a pressure of 4MPa. After the spray of the atomizer, it runs downward and meets phosphorus pentachloride gas. The volume ratio of phosphorus pentachloride to nitrogen is 10:1. The gas-solid phase reaction temperature is 400°C. The contact time with the gas is 60 minutes. The gas flow rate is controlled to ensure that the mass ratio of phosphorus pentachloride to molecular sieve is 0.8:1. The inner diameters of the buffer zone and the reaction zone are 0.4 meters and 0.2 meters respectively, and the heights are 0.5 meters and 0.2 meters respectively. The reacted material is purged for 40 minutes, and the gas is pumped out through the gas outlet pipe and enters the recovery system. The recovery system is a 12wt% sodium hydroxide solution, which neutralizes and collects the reacted gas. The molecular sieve is collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water: H2O=1:1, pH value is 2.5, washing temperature is 70℃, and washing time is 2.5h. After drying, it becomes Y3.

[0058] Example 4

[0059] Weigh 45 grams of cellulose and add it to a 16% ammonia solution with a liquid-solid ratio of 8. After treating at 115°C for 1 hour, add 300 grams of molecular sieve and 24 grams of zinc nitrate. After stirring for 70 minutes, enter the spray flash drying device and roast at 650°C for 150 minutes. Slowly add 230 grams of the roasted molecular sieve to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 150μm and a pressure of 3MPa. After spraying by the atomizer, the catalyst particles are dispersed in the reactor and run downward to meet phosphorus pentafluoride gas. The volume ratio of phosphorus pentafluoride to nitrogen is 0.5:1. The gas-solid phase reaction temperature is 500°C, and the contact time with the gas is 30 minutes. Control the gas flow rate to ensure that the mass ratio of phosphorus pentafluoride to molecular sieve is 0.78:1. The inner diameters of the buffer zone and the reaction zone are 0.3 meters and 0.15 meters, respectively, and the heights are 0.3 meters and 0.7 meters, respectively. The reacted material is purged in the absorption tower for 60 minutes, and the gas is discharged through the gas outlet pipe by pumping and enters the recovery system. The recovery system is a 15wt% sodium hydroxide solution, which neutralizes and collects the reacted gas. The molecular sieve is collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water: H2O=1:10, pH value is 3.5, washing temperature is 80℃, and washing time is 1.5h. The washed product is recorded as Y4.

[0060] Example 5

[0061] Weigh 20 grams of corn starch and add it to a 20% ammonia solution with a liquid-solid ratio of 4. After treating at 80°C for 2 hours, add 250 grams of molecular sieve and 12.5 grams of magnesium acetate. After stirring for 80 minutes, enter the spray flash drying device and roast at 650°C for 150 minutes. Slowly add 230 grams of the roasted molecular sieve to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 180μm and a pressure of 5MPa. After spraying by the atomizer, the molecular sieve runs downward and meets monochloramine. The volume ratio of monochloramine to nitrogen is 30:1. The gas-solid phase reaction temperature is 600°C, and the contact time with the gas is 50 minutes. Control the gas flow rate to ensure that the mass ratio of monochloramine to molecular sieve is 0.45:1. The inner diameters of the buffer zone and the reaction zone are 0.45 meters and 0.3 meters, respectively, and the heights are 0.7 meters and 0.5 meters, respectively. The gas after the reaction is discharged through the gas outlet pipe by pumping and enters the recovery system. The recovery system is a 10wt% sodium hydroxide solution. After the reacted material is purged in the absorption tower for 25 minutes, the gas is acid-base neutralized and collected. The molecular sieve is collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water: H2O=1:15, pH value is 4.8, washing temperature is 75°C, washing time is 1h, and the washed product is recorded as Y5.

[0062] Example 6

[0063] Weigh 17 grams of carboxymethyl cellulose and add it to an 8% ammonia solution with a liquid-solid ratio of 3. After treating at 90°C for 5 hours, add 100 grams of molecular sieve and 9 grams of cerium chloride. After stirring for 60 minutes, enter the spray flash drying device and roast at 750°C for 110 minutes. The roasted molecular sieve is slowly added to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 130μm and a pressure of 2.2MPa. After spraying by the atomizer, the molecular sieve runs downward and meets dichloramine. The volume ratio of dichloramine to nitrogen is 90:1, the gas-solid phase reaction temperature is 300°C, and the contact time with the gas is 20 minutes. The gas flow rate is controlled to ensure that the mass ratio of monochloramine to molecular sieve is 0.37:1. The inner diameters of the buffer zone and the reaction zone are 0.2 meters and 0.1 meters, respectively, and the heights are 0.4 meters and 0.6 meters, respectively. The reacted material was purged in the absorption tower for 30 minutes, and the gas was pumped out through the gas outlet pipe and entered the recovery system. The recovery system was a 5wt% sodium carbonate solution, which neutralized and collected the reacted gas. The molecular sieve was collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water was: H2O=1:8, pH value was 5.8, washing temperature was 85°C, and washing time was 0.5h. The washed product was recorded as Y6.

[0064] Example 7

[0065] Weigh 10 grams of neutral polyacrylamide and add it to a 23% ammonia solution with a liquid-to-solid ratio of 5. After treating at 100°C for 4 hours, add 200 grams of molecular sieve and 6 grams of lanthanum nitrate. After stirring for 90 minutes, enter the spray flash drying device and roast at 800°C for 60 minutes. The roasted molecular sieve is slowly added to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 70μm and a pressure of 3.5MPa. After spraying by the atomizer, the molecular sieve runs downward and meets trichloramine. The volume ratio of trichloramine to nitrogen is 60:1. The gas-solid phase reaction temperature is 800°C, and the contact time with the gas is 10 minutes. The gas flow rate is controlled to ensure that the mass ratio of trichloramine to molecular sieve is 0.23:1. The inner diameter of the buffer zone and the reaction zone are both 0.25 meters, and the heights are 0.6 meters and 0.9 meters respectively. After the reacted material is purged through the absorption tower for 20 minutes, the gas is pumped out through the gas outlet pipe and enters the recovery system. The recovery system is a 13wt% sodium hydroxide solution, which neutralizes and collects the reacted gas. After the catalytic molecular sieve agent is collected by the collector at the bottom of the absorption tower, it is first washed with water. The molecular sieve washed with water: H2O=1:23, pH value is 6.8, washing temperature is 95℃, and washing time is 0.5h. After washing, it is recorded as Y7.

[0066] Example 8

[0067] Weigh 36 grams of methyl cellulose and add it to a 3% ammonia solution with a liquid-solid ratio of 9. After treating at 85°C for 3.5 hours, add 300 grams of molecular sieve and 1.8 grams of yttrium hydroxide. After stirring for 120 minutes, enter the spray flash drying device and roast at 550°C for 80 minutes. The roasted molecular sieve is slowly added to the top of the descending bed reactor through a feeder. The top of the reactor is an atomizer with a gas eye diameter of 85μm and a pressure of 4.7MPa. After spraying by the atomizer, the molecular sieve runs downward and meets phosphorus trichloride gas. The volume ratio of phosphorus trichloride to nitrogen is 50:1. The gas-solid phase reaction temperature is 700°C. The contact time with the gas is 2 minutes. The gas flow rate is controlled to ensure that the mass ratio of phosphorus trichloride to molecular sieve is 0.14:1. The inner diameters of the buffer zone and the reaction zone are 0.3 meters and 0.15 meters, respectively, and the heights are 0.8 meters and 1 meter, respectively. After the reacted material is purged in the absorption tower for 50 minutes, the gas is pumped out through the gas outlet pipe and enters the recovery system. The recovery system is a 10wt% sodium carbonate solution, which neutralizes and collects the reacted gas. The molecular sieve is collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water: H2O=1:18, pH value is 3.8, washing temperature is 65℃, and washing time is 2h. The washed product is recorded as Y8.

[0068] Comparative Example 1

[0069] 200 grams of molecular sieves were put into the spray flash drying device and roasted at 800℃ for 60min. The roasted molecular sieves were slowly added to the top of the descending bed reactor through the feeder. The top of the reactor was an atomizer with a gas eye diameter of 70μm and a pressure of 3.5MPa. After the spraying of the atomizer, the molecular sieves moved downward and met trichloramine. The volume ratio of trichloramine to nitrogen was 60:1. The gas-solid phase reaction temperature was 800℃. The contact time with the gas was 10min. The gas flow rate was controlled to ensure that the mass ratio of trichloramine to molecular sieve was 0.23:1. The inner diameters of the buffer zone and the reaction zone were both 0.25 meters, and the heights were 0.6 meters and 0.9 meters respectively. After the reacted material was purged through the absorption tower for 20 minutes, the gas was discharged through the gas outlet pipe by pumping and entered the recovery system. The recovery system was a 13wt% sodium hydroxide solution, and the reacted gas was acid-base neutralized and collected. After the catalytic molecular sieve is collected by the collector at the bottom of the absorption tower, it is first washed with water. The molecular sieve washed with water: H2O=1:23, pH value is 6.8, washing temperature is 95°C, washing time is 0.5h, and the washed molecular sieve is recorded as Y9.

[0070] Comparative Example 2

[0071] 150 grams of molecular sieve and 3 grams of magnesium chloride were stirred for 100 minutes and then put into a spray flash drying device for calcination at 700°C for 240 minutes. Then 100 grams of calcined molecular sieve were slowly added to the top of the descending bed reactor through a feeder. The top of the reactor was an atomizer with a gas eye diameter of 80μm and a pressure of 4MPa. After the spraying of the atomizer, it ran downward and met with phosphorus pentachloride gas. The volume ratio of phosphorus pentachloride to nitrogen was 10:1. The gas-solid phase reaction temperature was 400°C. The contact time with the gas was 60 minutes. The gas flow rate was controlled to ensure that the mass ratio of phosphorus pentachloride to molecular sieve was 0.8:1. The inner diameters of the buffer zone and the reaction zone were 0.4 meters and 0.2 meters, respectively, and the heights were 0.5 meters and 0.2 meters, respectively. The reacted material was purged for 40 minutes, and the gas was discharged through the gas outlet pipe by pumping and entered the recovery system. The recovery system was a 12wt% sodium hydroxide solution, and the reacted gas was acid-base neutralized and collected. The molecular sieve is collected by the collector at the bottom of the absorption tower and then washed with water. The molecular sieve washed with water: H2O = 1:1, pH value is 2.5, washing temperature is 70°C, washing time is 2.5h. After drying, it becomes Y10.

[0072] Comparative Example 3

[0073] 300g molecular sieve and 24g zinc nitrate were stirred for 70min and then put into spray flash drying device for calcination at 650℃ for 150min. 230g of calcined molecular sieve was exchanged with ammonium chloride under the condition of liquid-solid ratio of 8, ammonium chloride / molecular sieve = 50%, exchange temperature: 90℃, pH value controlled at 3.5-4.0, exchange time for 90min. The exchanged molecular sieve was washed with deionized water, molecular sieve: H2O = 1:10, pH value 3.5, washing temperature 80℃, washing time 1.5h. The washed product was recorded as Y11.

[0074] Table 1 shows the crystallinity, specific surface area and pore volume results of the mesoporous Y-type molecular sieve obtained by using the patent of the present invention.

[0075] Table 1 Specific surface area and pore volume of prepared Y-type molecular sieve

[0076]

[0077] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing mesoporous molecular sieves by an ammonium-free method, characterized in that: The following steps are involved: The organic polymer is placed in an alkaline solution for depolymerization, and then a molecular sieve and a soluble modified metal compound are added, stirred evenly and then calcined, the calcined product is subjected to an isomorphous substitution reaction with a halogen-containing gas, and then washed with water to obtain a molecular sieve containing mesopores; The organic polymer is one or more of anionic, cationic or neutral polyacrylamide, carboxymethyl cellulose, methyl cellulose, cellulose and starch.

2. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The modified metal compound is one or more of a zinc salt, an alkaline earth metal salt and a rare earth metal compound, the zinc salt is zinc chloride and / or zinc nitrate, the alkaline earth metal salt is one or more of a chloride, a nitrate, a chlorate and an acetate, and the rare earth metal compound is one or more of a rare earth chloride, a rare earth nitrate and a rare earth hydroxide.

3. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The depolymerization temperature is 60-120°C and the depolymerization time is 0.5-6h.

4. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The depolymerization temperature is 70-100° C. and the depolymerization time is 1-4 hours.

5. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The amount of the organic polymer added is 1-20% of the mass of the molecular sieve; the amount of the modified metal compound added is 0.1-10% of the mass of the molecular sieve.

6. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The calcination is performed by spray flash drying at 500-850° C. for 30-240 min.

7. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The halogen-containing gas is one or more of phosphorus trichloride, phosphorus pentachloride, phosphorus trifluoride, phosphorus pentafluoride, monochloramine, dichloramine and trichloramine.

8. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The mass ratio of the halogen-containing gas to the calcined product is 0.01-0.8:1, the temperature of the isomorphous substitution reaction is 200-900° C., and the contact reaction time is 0.1-60 min.

9. The method for preparing mesoporous molecular sieves without ammonium according to claim 1, characterized in that: The mass ratio of the halogen-containing gas to the calcined product is 0.05-0.4:

1.

10. The method for preparing mesoporous molecular sieves by an ammonium-free method according to claim 1, characterized in that: In the water washing step, distilled water is used for washing, the mass ratio of molecular sieve to H2O is 1:1-25, the pH value of the formed molecular sieve slurry is 2.5-8.5, the washing temperature is 30-95°C, and the washing time is 0.5-2h.

11. The method for preparing mesoporous molecular sieves by an ammonium-free method according to claim 1, characterized in that: The isomorphous substitution reaction is carried out in a down-flowing bed isomorphous substitution reactor, the calcined product is added to the upper part of the reactor, and the halogen-containing gas is added from the lower part of the reactor for countercurrent contact.

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