Preparation method and device of rare earth-containing Y-type molecular sieve

Abstract

The application discloses a preparation method of a rare earth-containing Y-type molecular sieve, and comprises the following steps: S1, slushing NaY molecular sieve, humic acid and water, filtering, and forming a NaY molecular sieve filter cake; S2, mixing and slushing NaY molecular sieve, a rare earth salt and an ammonium salt-containing solution, obtaining RE-NaY one-interchange molecular sieve slurry, placing the RE-NaY one-interchange molecular sieve slurry on the NaY molecular sieve filter cake, filtering, obtaining a RE-NaY one-interchange molecular sieve composite filter cake, washing, drying and calcining the RE-NaY one-interchange molecular sieve composite filter cake, and obtaining a one-calcined molecular sieve; S3, slushing the one-calcined molecular sieve and water, filtering to obtain a filter cake, and then exchanging the filter cake with an ammonium salt solution and washing with water, and obtaining the rare earth-containing Y-type molecular sieve. The preparation method of the rare earth-containing Y-type molecular sieve provided by the application recovers the lost ammonium ions and rare earth ions in the filter liquid through the NaY molecular sieve filter cake layer and the humic acid adsorption, and realizes the recycling of the ammonium ions and the rare earth.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of molecular sieve materials and preparation thereof, in particular to a preparation method and device of rare earth-containing Y-type molecular sieve. BACKGROUND

[0002] Fluid catalytic cracking (FCC) is a very important process in petroleum refining process, and plays a vital role in refineries. About 70-80% of domestic gasoline is obtained from the catalytic cracking process. With the continuous introduction of environmental protection regulations and emission standards, the limitation on the quality of FCC gasoline is becoming more and more strict, and the limitation on the content of olefins is also more and more strict. Therefore, the research and development of catalytic cracking catalysts with the ability to reduce olefins has always been paid attention by researchers.

[0003] At present, the active component of the FCC catalyst widely used for reducing the content of olefins in gasoline is a rare earth-containing Y-type molecular sieve. In order to exchange a proper amount of rare earth on the molecular sieve, it is hoped that the cation sites on the molecular sieve are partially occupied by ammonium ions. In this case, the rare earth-containing Y-type molecular sieve is obtained by simultaneously or separately exchanging, filtering, drying or not drying the filter cake, and then calcining the NaY molecular sieve with an ammonium solution and a rare earth solution.

[0004] Patent CN1053808A discloses a preparation method of REY molecular sieve suitable for hydrocarbon cracking catalyst. NaY molecular sieve is exchanged with RE 3+ After one ion exchange in an aqueous solution, the molecular sieve is calcined at 450-600℃ in 100% flowing water vapor for 1-3 hours, and then further exchanged with NH4 + or washed with water.

[0005] Patent ZL200410096002.1 discloses a preparation method of a rare earth-containing ultra-stable Y-type molecular sieve cracking catalyst. The method is characterized in that the NaY molecular sieve is contacted twice or more than twice with an aqueous solution containing 6-94% by weight of ammonium salt at normal pressure and a temperature greater than 90℃ and not greater than the boiling point of the aqueous ammonium salt solution, with the weight ratio of the ammonium salt to the molecular sieve being 0.1-24, so that the Na2O content in the molecular sieve is reduced to less than 1.5% by weight. Then, the molecular sieve is contacted with an aqueous solution containing 2-10% by weight of rare earth salt at 70-95℃, so that the rare earth content in the molecular sieve is 0.5-18% by weight as RE2O3, and then mixed with a carrier and dried.

[0006] There are two problems in the current industrial production of rare earth Y-type molecular sieve: 1) In order to reduce the sodium content to meet the requirements of catalyst preparation, a large amount of ammonium salt is used in the ion exchange process, resulting in a large amount of ammonia-nitrogen wastewater; 2) The utilization rate of rare earth ions is low in the rare earth ion exchange process, and a considerable part of the rare earth ions remains in the exchange solution after liquid phase exchange, and is discharged with the filtrate after filtration, resulting in high cost of molecular sieve preparation.

[0007] Patent CN110862095A discloses a preparation method of rare earth Y-type molecular sieve, which is characterized in that NaY molecular sieve is contacted with a rare earth solution or a mixed solution of rare earth and ammonium salt, filtered, washed with water and dried, then subjected to first calcination treatment to obtain rare earth sodium Y molecular sieve; then the rare earth sodium Y molecular sieve is slurried and contacted with an acid solution, filtered, mixed with a rare earth solution, and the pH value of the slurry is adjusted to 5-6 with ammonia water, filtered or not, dried, and subjected to second calcination treatment to obtain rare earth Y-type molecular sieve. Compared with the prior art, the method can effectively reduce the cost of raw materials, the utilization rate of rare earth in the molecular sieve is more than 98%, the ammonia-nitrogen content in the wastewater is reduced by 30-50%, the wastewater treatment cost is reduced, and energy saving and environmental protection are achieved.

[0008] Patent CN101088613 discloses a preparation method of REY molecular sieve, which is characterized in that NaY molecular sieve is contacted with an aqueous solution containing rare earth ions or with an aqueous solution containing rare earth ions and a solution or colloid containing aluminum ions, then contacted with an additional precipitant to precipitate part of the rare earth on the molecular sieve, subjected to hydrothermal treatment, and finally contacted with an aqueous ammonium salt solution, wherein the precipitant is a soluble carbonate aqueous solution or an alkaline aqueous solution.

[0009] Patent CN100344374C discloses a preparation method of rare earth Y molecular sieve, which is a one-exchange-one-calcination process, in which the pH value of the solution is adjusted to 8-11 with an alkaline solution after one exchange, then the solution is filtered, washed with water, dried and calcined, or the molecular sieve filter cake is separated after one exchange, the filtrate is collected, an alkaline solution is added to adjust the pH value of the solution to 8-11, and then the obtained rare earth hydroxide filter cake and molecular sieve filter cake are slurried with water, filtered, washed with water, dried and calcined. This process precipitates the excess rare earth ions in the solution to avoid loss of rare earth.

[0010] Patent CN1733362 discloses a kind of rare earth Y molecular sieve and its preparation method, the method is that NaY molecular sieve slurry is exchanged with or without ammonium salt, then ion exchange is carried out with rare earth chloride according to the weight ratio of NaY dry basis:RECl3=1:0.17-0.35 at 5-100℃, pH=2.5-7.5, the weight ratio of water to NaY is 3-50, then the solution pH is adjusted to 8-11 with alkaline solution, stirring, filtering, washing, drying, then calcining for more than 0.1 hour under high temperature and water vapor conditions, the calcined molecular sieve is exchanged again according to the weight ratio of molecular sieve dry basis:ammonium salt:water=1:0-1:2-50 at 60-100℃, and the product REY is obtained after washing, filtering and drying.

[0011] Patent CN103058217B discloses a preparation method of Y molecular sieve containing rare earth, which comprises the following steps: taking NaY molecular sieve as raw material, first carrying out ammonium exchange treatment, then carrying out water vapor treatment, treating the Y molecular sieve after water vapor treatment with a mixed solution containing H + , NH4 + , RE 3+ and organic solvent, and finally drying to obtain finished product. The method adds organic reagent in ion exchange solution to enhance the ion exchange capacity of rare earth.

[0012] Patent CN103508467B discloses a method for preparing rare earth Y molecular sieve, which is characterized in that NaY molecular sieve is contacted with a rare earth solution or a mixed solution of rare earth solution and ammonium salt, and then filtered, washed with water and dried, followed by calcination to obtain rare earth sodium Y molecular sieve; then the rare earth sodium Y molecular sieve is slurried and contacted with an ammonium salt solution without filtration, mixed with a rare earth solution and adjusted to a pH of the slurry with an alkaline liquid to deposit rare earth, followed by filtration, drying and second calcination to obtain rare earth Y molecular sieve. The method has high rare earth utilization rate and effectively reduces the production cost of molecular sieve.

[0013] Patent CN103130240A discloses a preparation method of modified Y-type molecular sieve, which adopts a process of two exchanges and two calcinations combined with rare earth deposition. In the preparation process, the pH value of slurry in the rare earth deposition process is adjusted to a range of 6-10. The method has high ammonia-nitrogen content in wastewater and great environmental protection pressure.

[0014] As can be seen from the above, the methods provided in the above patents can only improve the utilization rate of rare earth or reduce the ammonia-nitrogen content in wastewater, and cannot simultaneously solve the problems of rare earth loss in the exchange process of Y-type molecular sieve and reduction of ammonia-nitrogen wastewater discharge.

[0015] There are two methods for ammonium and rare earth ion exchange of sodium type Y molecular sieve in industry: the first method is to mix Y type molecular sieve with aqueous solution containing ammonium ion and / or rare earth ion, and then to carry out ion exchange, filtration, washing, drying, and calcination or non-calcination. In the method, plate and frame filter is used. The method has the disadvantages of low efficiency and large water consumption; the second method is to mix Y type molecular sieve with water to form a slurry, and then to continuously transfer the slurry to the filter cloth of a belt filter to form a filter cake with a certain thickness on the filter cloth, and then to add aqueous solution containing ammonium ion and / or rare earth ion from the top of the filter cake, and to continuously pass the solution through the filter cake under the action of vacuum in the liquid receiver under the filter cloth to carry out ion exchange. The belt filter has the characteristics of energy saving and high efficiency, and is widely used in large-scale industrial production.

[0016] US3943233 discloses a method for continuously ion exchanging fluidizable zeolite particles, which comprises mixing the zeolite particles with a first liquid to form a slurry, continuously feeding the slurry to the feed end of a continuous horizontal belt vacuum filter at a substantially constant rate, continuously moving the filter belt loaded with the slurry through a filter cake forming zone, at least one ion exchange zone and a washing zone, and simultaneously applying vacuum to the liquid receiver under each separate filter belt to discharge the filter cake from the filter belt. The method is characterized in that the filter cake leaving the filter cake forming zone is substantially free of surface cracks, but contains liquid in the interstices of the fluidizable zeolite particles, and in the ion exchange process, the filter cake is contacted with an ion exchange liquid in the ion exchange zone under filtration conditions, and the filter cake leaves the ion exchange zone in the form of a cake which is smooth, substantially free of surface cracks, and contains liquid in the interstices of the fluidizable zeolite particles, and the ion exchanged filter cake is rapidly washed under vacuum.

[0017] CN1142024C discloses a method for ion exchanging rare earth ions of molecular sieve, which comprises mixing a molecular sieve with water to form a slurry, continuously transferring the slurry to the filter belt of a horizontal belt vacuum filter, sequentially passing through a filter cake forming zone and an ion exchange zone, applying vacuum to the liquid receiver under the filter cake forming zone and the ion exchange zone, washing and drying the filter cake, and discharging the filter cake from the filter belt, and is characterized in that the molecular sieve refers to Y type molecular sieve after ion exchange and calcination, acid and / or salt are added to the slurry, the amount of the acid or salt is 0.1-5% by weight based on the amount of the molecular sieve, the vacuum degree in the liquid receiver of the filter cake forming zone ensures that the surface of the filter cake is substantially free of cracks, and the solution containing rare earth ions is added to the upper part of the filter cake in the ion exchange zone, and the concentration of the solution containing rare earth ions is such that the weight ratio of rare earth oxide to the molecular sieve is 0.01-0.5%.

[0018] CN1485136A continuously loads a PH2-7 molecular sieve slurry on the filter cloth of a horizontal belt filter, and sequentially passes the filter cloth loaded with the molecular sieve slurry through a filter cake forming zone, an ion exchange zone and a water washing zone, then absorbs dry, unloads and dries, and finally obtains the exchanged molecular sieve filter cake. In the ion exchange zone, a rare earth compound aqueous solution with a temperature of 10-100°C is added from the upper part of the filter cake, and the amount of the rare earth compound aqueous solution is such that the weight ratio of rare earth oxide to molecular sieve is 0.01-0.2.

[0019] Patent ZL02130783.0 discloses a method for ammonium and rare earth ion exchange of molecular sieve, which comprises continuously loading a molecular sieve slurry on the filter cloth of a horizontal belt filter, sequentially passing the filter cloth loaded with the molecular sieve slurry through a filter cake forming zone, a first ion exchange zone, a first washing zone, a second ion exchange zone and a second washing zone, and uniformly mixing, drying and calcining the obtained filter cake. The method realizes rare earth ion and ammonium ion exchange of the molecular sieve on a belt filter using ammonium sulfate as the ammonium source, and prepares a rare earth-containing molecular sieve product.

[0020] Patent ZL02146392.1 discloses a method for ammonium and rare earth ion mixed exchange of molecular sieve, which comprises slushing the molecular sieve with water, continuously loading the obtained slurry on the filter cloth of a horizontal belt filter, sequentially passing through a filter cake forming zone and an ion exchange zone, washing and absorbing the filter cake, unloading the filter cake from the filter cloth, wherein the molecular sieve is a Y-type molecular sieve with one exchange and one calcination, the slurry further contains acid and / or salt, the amount of the acid and / or salt is 0.1-5% by weight of the molecular sieve, the vacuum degree in the liquid receiver of the filter cake forming zone ensures that there is substantially no crack on the surface of the filter cake, in the ion exchange zone, a mixed aqueous solution containing ammonium salt and rare earth compound is added from the upper part of the filter cake, the amount of the mixed aqueous solution containing ammonium salt and rare earth compound is such that the weight ratio of rare earth oxide to molecular sieve is 0.01-0.2, and the weight ratio of ammonium salt to molecular sieve, calculated based on ammonium chloride, is 0.01-0.4. The patent successfully completes the exchange of the Y-type molecular sieve with one exchange and one calcination on the belt filter using ammonium salt and rare earth compound.

[0021] The above-mentioned molecular sieve belt filter exchange patents only provide methods for ammonium and rare earth ion exchange of molecular sieve, and do not involve the technical problem of improving the utilization rate of rare earth ions and ammonium ions in the ion exchange process. Therefore, how to effectively improve the utilization rate of ammonium ions and rare earth in the ion exchange process of the rare earth-containing Y-type molecular sieve belt filter, reduce the discharge of ammonia-nitrogen wastewater and the loss of rare earth is an important measure for molecular sieve production enterprises to reduce costs and increase benefits, and is one of the key research topics of molecular sieve production enterprises. SUMMARY

[0022] The application aims to provide a preparation method of rare earth Y-type molecular sieve, so as to solve the problems of low utilization rate of rare earth and serious ammonia nitrogen pollution in the production process of rare earth Y-type molecular sieve in the prior art.

[0023] The application also aims to provide a device for preparing rare earth Y-type molecular sieve.

[0024] To achieve the above-mentioned purpose, the application provides a preparation method of rare earth Y-type molecular sieve, comprising the following steps:

[0025] S1, beating up NaY molecular sieve, humic acid and water, filtering to form NaY molecular sieve filter cake;

[0026] S2, mixing and beating up NaY molecular sieve, rare earth salt and ammonium salt solution to obtain RE-NaY one-interchange molecular sieve slurry, placing the RE-NaY one-interchange molecular sieve slurry on the NaY molecular sieve filter cake, filtering to obtain RE-NaY one-interchange molecular sieve composite filter cake, washing, drying and calcining the RE-NaY one-interchange molecular sieve composite filter cake to obtain one calcined molecular sieve;

[0027] S3, filtering the filter cake after beating up one calcined molecular sieve with water, then exchanging the filter cake with ammonium salt solution and washing with water to obtain rare earth Y-type molecular sieve.

[0028] In the preparation method of rare earth Y-type molecular sieve, the slurry after beating up in step S1 is adjusted to a pH of 6-10, preferably 7-9, by using acid, and then filtered, the acid is one or more of oxalic acid, citric acid, phosphoric acid, hydrochloric acid, sulfuric acid and nitric acid, preferably oxalic acid and / or citric acid.

[0029] In the preparation method of rare earth Y-type molecular sieve, the dry weight ratio of humic acid to NaY molecular sieve in step S1 is 0.01-0.03:1, and the humic acid is one or more of yellow humic acid, brown humic acid and black humic acid.

[0030] In the preparation method of rare earth Y-type molecular sieve, in step S2, the weight ratio of rare earth salt (calculated as rare earth oxide) to NaY molecular sieve is 0.12-0.35:1, the weight ratio of ammonium salt solution (calculated as solution mass) to NaY molecular sieve is 2-10:1, preferably 3-6:1, the beating up temperature is 50-100 DEG C, the beating up time is 0.5-2 hours, and the ammonia nitrogen content in the ammonium salt solution is 500-3500 ppm.

[0031] In the preparation method of rare earth Y-type molecular sieve, in step S3, the weight ratio of ammonium salt to one calcined molecular sieve is 0.1-0.25:1.

[0032] The preparation method of the rare earth Y-type molecular sieve provided by the application is characterized in that the NaY molecular sieve has a sodium content of 9-15%.

[0033] The preparation method of the rare earth Y-type molecular sieve provided by the application is characterized in that the rare earth salt is a nitrate or chloride of the rare earth, and the rare earth is one or more of lanthanum, cerium, praseodymium, neodymium and yttrium.

[0034] The preparation method of the rare earth Y-type molecular sieve provided by the application is characterized in that the ammonium salt in step S2 and the ammonium salt in step S3 are each independently one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate and ammonium bicarbonate, and preferably ammonium chloride and / or ammonium sulfate.

[0035] The preparation method of the rare earth Y-type molecular sieve provided by the application is characterized in that the filtrate for forming the RE-NaY one-interchange molecular sieve composite filter cake in step S2 and the exchange solution obtained by ion exchange in step S3 are recycled as the ammonium salt-containing solution in step S2.

[0036] To achieve the above-mentioned purpose, the application further provides a device for preparing a rare earth Y-type molecular sieve, which comprises a horizontal belt filter, and the horizontal belt filter comprises a NaY molecular sieve filter cake forming area, a one-interchange molecular sieve filter cake forming area and an ion exchange area, wherein the NaY molecular sieve filter cake forming area is used for forming a NaY molecular sieve filter cake, the one-interchange molecular sieve filter cake forming area is used for forming a RE-NaY one-interchange molecular sieve composite filter cake on the NaY molecular sieve filter cake, and the ion exchange area is used for ion exchange between the ammonium salt-containing solution and the composite filter cake.

[0037] The application has the following beneficial effects:

[0038] The preparation method of the rare earth Y-type molecular sieve provided by the application is characterized in that the ammonium salt in step S2 and the ammonium salt in step S3 are each independently one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate and ammonium bicarbonate, and preferably ammonium chloride and / or ammonium sulfate. + , effectively removing Na + from the NaY molecular sieve layer. The humic acid added in the NaY molecular sieve slurry in the application is a multi-element organic complex, which can limit the migration of ammonium ions and rare earth ions in the filtrate through adsorption, and inhibit the loss of ammonium ions and rare earth ions with the filtrate. The preparation method of the rare earth Y-type molecular sieve provided by the application recovers the lost ammonium ions and rare earth ions in the filtrate through the NaY molecular sieve filter cake layer and the humic acid, and realizes the recycling of ammonium ions and rare earth. Therefore, compared with the prior art, the preparation method of the rare earth Y-type molecular sieve provided by the application can exchange Na +And the ammonium and rare earth can reach 100% utilization. Moreover, the preparation method of the rare earth-containing Y-type molecular sieve provided by the application does not need to add additional reagents, the process is simple, and the recycling of ammonium and rare earth ions is realized in the molecular sieve exchange process, which can provide technical support for continuous production of molecular sieves and energy saving and consumption reduction of enterprises. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A flow chart of the first exchange process of the molecular sieve of the application;

[0040] Figure 2 A flow chart of the second exchange process of the molecular sieve of the application.

[0041] In the drawings, reference signs are:

[0042] 1, 5, 12 pulp tank;

[0043] 2, 6, 10, 13, 17, 21 pipeline;

[0044] 3, 14 filter cloth;

[0045] 4 NaY filter cake formation area

[0046] 7 first exchange molecular sieve filter cake formation area

[0047] 8, 19 liquid receiver

[0048] 9, 16, 20 container

[0049] 11, 22 water washing area

[0050] 15 second exchange filter cake formation area

[0051] 18 ion exchange area

[0052] 19 vacuum box

[0053] 23 recovered filtrate DETAILED DESCRIPTION

[0054] The application will be specifically described below by examples. It is necessary to point out here that the following examples are only used to further illustrate the application and cannot be understood as limiting the protection scope of the application, and those skilled in the art can make some non-essential improvements and adjustments to the application according to the above content of the application.

[0055] The application provides a preparation method of a rare earth-containing Y-type molecular sieve, comprising the following steps:

[0056] S1, pulp beating NaY molecular sieve, humic acid and water, filtering to form a NaY molecular sieve filter cake;

[0057] S2, mixing the NaY molecular sieve, the rare earth salt and the solution containing the ammonium salt to obtain a RE-NaY one-interchange molecular sieve slurry, placing the RE-NaY one-interchange molecular sieve slurry on the NaY molecular sieve filter cake, filtering to obtain a RE-NaY one-interchange molecular sieve composite filter cake, and washing, drying and calcining the RE-NaY one-interchange molecular sieve composite filter cake to obtain a calcined molecular sieve;

[0058] S3, slurring the calcined molecular sieve with water, filtering to obtain a filter cake, and then exchanging the filter cake with an ammonium salt solution and washing to obtain the rare earth-containing Y-type molecular sieve.

[0059] The preparation method of the rare earth-containing Y-type molecular sieve provided by the present application first forms a NaY molecular sieve filter cake, then loads the Y-type molecular sieve after the exchange of the ammonium salt and the rare earth on the NaY molecular sieve filter cake layer to form a RE-NaY one-interchange molecular sieve composite filter cake. During the formation of the RE-NaY one-interchange molecular sieve composite filter cake or in the subsequent ion exchange process, the unexchanged ammonium ions and rare earth ions can be further adsorbed by the NaY filter cake through the adsorption characteristics of the NaY filter cake for ammonium ions and rare earth ions. At the same time, the excess ammonium ions and rare earth ions can also exchange part of the Na + of the NaY molecular sieve layer when passing through the NaY molecular sieve layer. + Therefore, the adsorption and ion exchange of the NaY molecular sieve can further recover the ammonium ions and rare earth ions lost in the filtrate, realizing the effective utilization of the ammonium salt and the rare earth. The humic acid added in the NaY molecular sieve slurry is a multi-element organic complex, which can limit the migration of ammonium ions and rare earth ions in the filtrate through adsorption, and inhibit the loss of ammonium ions and rare earth ions with the filtrate.

[0060] The Y-type molecular sieve to be ion-exchanged is not particularly limited in the present application, and in an embodiment, the Y-type molecular sieve of the present application is a Y-type molecular sieve containing Na + , i.e. a NaY molecular sieve; in another embodiment, the mass content of sodium oxide in the NaY molecular sieve of the present application is 9-15%. The NaY molecular sieve and its preparation method are known to those skilled in the art. For example, the synthesis method of the NaY molecular sieve provided in patent CN103449468B: mixing water glass, sodium metaaluminate and deionized water, aging at 15-70℃ for 0.5-48 hours to obtain a crystallization directing agent; uniformly mixing the crystallization directing agent, water glass, an acidic aluminum salt and a sodium aluminate solution to prepare a silica-alumina gel; crystallizing the silica-alumina gel at 80-140℃; crystallizing for 0.1-80 hours; adding a peroxide to the crystallized silica-alumina gel, so that the molar ratio of O2 2- in the peroxide to Al2O3 in the gel is 0.05-20, and continuing to crystallize for 5-20 hours to obtain the product.

[0061] In addition, the source of the NaY molecular sieve is not particularly limited in the present application, and the NaY molecular sieve can be prepared by a conventional method or purchased commercially.

[0062] Firstly, the NaY molecular sieve to be ion-exchanged is formed into a slurry, for example, the NaY molecular sieve is slurried with water to form a slurry. The slurring conditions of the NaY molecular sieve with water are well known to those skilled in the art, for example, the content of the NaY molecular sieve in the slurry is generally 100-300 g / L. The slurring temperature can be 10-100°C, preferably 50-90°C.

[0063] The ion-exchanged molecular sieve can be treated by water washing, drying and calcination, and the water washing conditions are well known to those skilled in the art, and the present application is not particularly limited, for example, the water washing temperature is 20-100°C, preferably 60-80°C, and the water amount is 1-15 times, preferably 3-5 times the mass of the molecular sieve. The drying and calcination conditions are well known to those skilled in the art, and the present application is not particularly limited, for example, the drying temperature is room temperature to 200°C, preferably 100-150°C, the calcination temperature is 500-800°C, preferably 600-700°C, and the calcination time is 1-3 hours, preferably 2-3 hours.

[0064] The filter cake of the water-washed molecular sieve in step S3 is dried and calcined or not spray-dried and calcined to obtain the rare earth-containing Y-type molecular sieve.

[0065] In an embodiment, the slurry after slurring in step S1 is filtered after adjusting the pH to 6-10, preferably 7-9, using an acid, and the acid is one or more of oxalic acid, citric acid, phosphoric acid, hydrochloric acid, sulfuric acid and nitric acid, preferably oxalic acid and / or citric acid.

[0066] In an embodiment, the weight ratio of the humic acid to the NaY molecular sieve in step S1 is 0.01-0.03:1, and the humic acid is one or more of fulvic acid, humic acid and humin acid.

[0067] In an embodiment, the weight ratio of the rare earth salt to the NaY molecular sieve in step S2 is 0.12-0.35:1, and the weight ratio of the ammonium salt solution to the NaY molecular sieve is 2-10:1, preferably 3-6:1, the slurring temperature is 50-100°C, the slurring time is 0.5-2 hours, and the ammonia nitrogen content in the ammonium salt solution is 500-3500 ppm.

[0068] In an embodiment, the weight ratio of the ammonium salt to the calcined molecular sieve in step S3 is 0.1-0.25:1.

[0069] In an embodiment, the NaY molecular sieve contains 9-15% of sodium oxide.

[0070] In one embodiment, the rare earth salt is a nitrate or chloride salt of a rare earth, and the rare earth is one or more of lanthanum, cerium, praseodymium, neodymium and yttrium.

[0071] In one embodiment, the ammonium salt-containing solution in step S2 and the ammonium salt in step S3 are each independently one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate and ammonium bicarbonate, preferably ammonium chloride and / or ammonium sulfate.

[0072] In one embodiment, the filtrate formed in step S2 in the formation of the RE-NaY-one exchange molecular sieve composite filter cake and the exchange solution obtained in step S3 by ion exchange are recycled as the ammonium salt-containing solution in step S2. Other ammonium salt-containing solutions collected in the process can also be used as the ammonium salt-containing solution in step S2, so that the ammonium salt can be fully utilized and zero ammonia-nitrogen wastewater discharge can be achieved.

[0073] The present application also provides a device for preparing a rare earth Y-type molecular sieve, comprising a horizontal belt filter, which comprises a NaY molecular sieve filter cake formation zone, a one exchange molecular sieve filter cake formation zone and an ion exchange zone, wherein the NaY molecular sieve filter cake formation zone is used to form a NaY molecular sieve filter cake, the one exchange molecular sieve filter cake formation zone is used to form a RE-NaY-one exchange molecular sieve composite filter cake on the NaY molecular sieve filter cake, and the ion exchange zone is used for ion exchange between an ammonium salt-containing solution and the composite filter cake.

[0074] I. Formation of NaY filter cake

[0075] NaY molecular sieve slurry (comprising NaY molecular sieve, humic acid, water) at 10-100°C, preferably 50-90°C, is continuously loaded from a beater tank 1 through a pipeline 2 onto a filter cloth 3 of a horizontal vacuum belt filter, the filter cloth continuously moves into a NaY filter cake formation zone 4. A liquid receiver 8 is located below the filter cloth 3, and the liquid receiver 8 is vacuumed, under the action of vacuum, the liquid in the slurry on the filter cloth 3 passes through the filter cloth 3 into the liquid receiver 8. At the same time, the NaY slurry on the filter cloth 3 forms a filter cake, and the loading speed of the NaY slurry should ensure that the thickness of the NaY filter cake is 0.5-1.5 centimeters, preferably 0.8-1.5 centimeters. The vacuum degree in the vacuum box 8 makes the surface of the filter cake free of cracks. The vacuum degree in the vacuum box 8 is generally 0.02-0.08 MPa, preferably 0.05-0.08 MPa.

[0076] II. Formation of one exchange filter cake

[0077] A 50-100°C first-interchange molecular sieve slurry (including NaY molecular sieve, rare earth salt, ammonium salt solution) is continuously loaded from a beater tank 5 through a pipeline 6 onto a NaY filter cake layer of a horizontal vacuum belt filter, and moves with the filter cloth into a first-interchange molecular sieve filter cake formation zone 7. Under the action of a liquid receiver 8, the first-interchange molecular sieve slurry passes through the NaY filter cake layer and the filter cloth, and forms a first-interchange molecular sieve filter cake on the NaY filter cake. The loading speed of the first-interchange molecular sieve slurry should ensure that the thickness of the first-interchange molecular sieve filter cake is 0.5-1.5 cm, and preferably 0.8-1.5 cm.

[0078] Three, first-interchange washing

[0079] The washing method is known to those skilled in the art. The filter cake obtained in the first-interchange molecular sieve filter cake formation zone 7 moves with the filter cloth into a water washing zone 11. Deionized water is added from a container 9 through a pipeline 10. The weight ratio of deionized water to molecular sieve is generally 1-15, and preferably 2-10. The temperature of the deionized water is 20-100°C, and preferably 30-90°C. Under the action of vacuum, the liquid permeates through the filter cake, and the residual ions, especially anions, in the filter cake are washed away.

[0080] Four, formation of a calcined molecular sieve slurry

[0081] The filter cake after water washing is dried and calcined to obtain a calcined molecular sieve. The calcined molecular sieve is slurried with water to form a calcined molecular sieve slurry.

[0082] Five, formation of a second-interchange filter cake

[0083] A 10-100°C, and preferably 50-90°C calcined molecular sieve slurry is continuously loaded from a beater tank 12 through a pipeline 13 onto a filter cloth 14 of a horizontal vacuum belt filter. The filter cloth continuously moves into a second-interchange filter cake formation zone 15. A liquid receiver 19 is located below the filter cloth 14. The liquid receiver 19 is vacuumed. Under the action of vacuum, the liquid in the slurry on the filter cloth 14 passes through the filter cloth 14 into the liquid receiver 19. At the same time, the calcined molecular sieve slurry on the filter cloth 14 forms a filter cake. The loading speed of the calcined molecular sieve slurry should ensure that the thickness of the calcined molecular sieve filter cake is 0.5-2.0 cm, and preferably 0.8-1.5 cm. The vacuum degree in the vacuum box 19 prevents the filter cake surface from cracking. The vacuum degree in the vacuum box 19 is generally 0.02-0.08 MPa, and preferably 0.03-0.08 MPa.

[0084] Five, second-interchange ammonium ion exchange

[0085] As the filter cloth 14 moves, the filter cake formed in the second-interchange filter cake formation zone 15 enters an ion exchange zone 18. An ammonium salt solution with a temperature of 20-100°C, and preferably 30-90°C is added from a container 16 through a pipeline 17. Under the action of vacuum, the ammonium salt solution passes through the filter cake while ion exchange is carried out.

[0086] Six, two cross washing

[0087] The washing method is well known to those skilled in the art. The filter cake obtained in the ion exchange zone 18 is moved with the filter cloth into the water washing zone 22, and deionized water is added from the container 20 through the pipeline 21. The weight ratio of the deionized water to the molecular sieve is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100°C, preferably 30-90°C. Under the action of vacuum, the liquid permeates the filter cake, and the residual ions in the filter cake are washed away.

[0088] The recovered filtrate 23 received by the molecular sieve two-cross process liquid receiver 19 can be used as an ammonium salt-containing solution for the formation of a one-cross molecular sieve slurry, which on the one hand reduces the amount of water used, and on the other hand recovers the ammonium ions in the two-cross process filtrate, reduces the amount of sewage discharged, and improves the utilization rate of ammonium salt.

[0089] The technical solutions of the present application will be further described in detail below through specific examples.

[0090] Raw material sources:

[0091] 1) NaY molecular sieve: industrial product, produced by Lanzhou Petrochemical Company, crystallinity 94%, silicon-aluminum ratio 5, Na2O content 14.3%;

[0092] 2) Lanthanum chloride, cerium nitrate, yttrium chloride, oxalic acid, citric acid, ammonium sulfate, ammonium chloride, hydrochloric acid, sulfuric acid, fulvic acid, brown humic acid, black humic acid, ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium oxalate, ammonium bicarbonate: analytical pure, all are chemical reagents.

[0093] Evaluation and analysis methods:

[0094] 1) Sodium oxide and rare earth oxide content: analyzed by X-ray fluorescence spectroscopy.

[0095] 2) Filtrate ammonia nitrogen content: detected by Nessler's reagent spectrophotometry. Specific examples:

[0097] The following examples use a cloth funnel filter device to conduct experiments to illustrate the method provided by the present application. Since the cloth funnel filter device also goes through the stages of filter cake formation, ion exchange and washing, only these steps are carried out separately, and thus are equivalent to the continuous process on the belt filter.

[0098] Comparative Example 1

[0099] A one-roast molecular sieve sample was prepared according to the method provided in the patent CN1216687C.

[0100] I. Filter cake formation

[0101] The NaY molecular sieve is mixed with deionized water to prepare a slurry with a pH of 9 and a solid content of 100 g / L. The slurry is heated to 70°C under stirring and poured into a Buchner funnel. At the same time, the filter cake in the Buchner funnel is vacuumed to 0.05 MPa. Under the action of vacuum, a filter cake with a thickness of about 1.2 cm is formed on the filter cloth of the Buchner funnel, and the waste liquid in the filter bottle is emptied.

[0102] II. Ion exchange

[0103] The vacuum in the filter bottle is maintained, and when the surface of the filter cake is about to be free of liquid, an aqueous lanthanum chloride solution containing 50 g / L of lanthanum oxide at a temperature of 65°C is slowly added. The addition rate is such that liquid is always present on the surface of the filter cake until the weight ratio of rare earth lanthanum oxide to molecular sieve in the aqueous solution is 0.15.

[0104] III. Washing

[0105] The vacuum in the filter bottle is maintained, and when the surface of the filter cake is about to be free of liquid, deionized water at a temperature of 65°C is slowly added. The addition rate of deionized water is such that liquid is always present on the surface of the filter cake until the amount of deionized water added is three times the weight of the molecular sieve in the filter cake.

[0106] IV. Drying

[0107] The vacuum is continued until no liquid flows out of the funnel, and a dried filter cake and a filtrate A are obtained.

[0108] V. Removing the filter cake and drying

[0109] The filter cloth is removed from the funnel, and the filter cake is removed from the filter cloth and dried at 140°C to obtain a calcined molecular sieve. The sodium oxide content of the calcined molecular sieve is 4.3%, the rare earth content is 13.6%, and the utilization rate of rare earth is 90.6%.

[0110] Then, the sample is prepared according to the method provided in Patent CN1142024C.

[0111] The calcined molecular sieve prepared in the above, deionized water and the filtrate A described above were mixed and slurried to produce a molecular sieve-containing slurry having a molecular sieve content of 120 g / L, wherein the amount of salt (i.e., the lanthanum chloride and sodium chloride contained in the filtrate used) was 1.1 wt% of the molecular sieve. The resulting molecular sieve slurry was heated to 90°C and poured into a Buchner funnel while the filter flask was evacuated to 0.07 MPa, forming a filter cake having a thickness of 10 mm on the filter cloth. When no liquid was present on the surface of the filter cake, a solution containing ammonium chloride having a temperature of 90°C was immediately added at a rate that ensured that no cracks formed on the surface of the filter cake, and the amount of the ammonium chloride solution was such that the weight ratio of ammonium chloride to molecular sieve was 0.10. When no liquid was present on the surface of the filter cake, deionized water having a temperature of 90°C was immediately added to wash the filter cake, and the weight ratio of deionized water to molecular sieve was 5. The filter cake was then removed and the filtrate B was collected, and the filter cake was dried at 120°C to produce a rare earth Y-type molecular sieve D1. The sodium oxide content of the D1 molecular sieve sample was 1.1%, the rare earth content was 13.8%, the rare earth utilization rate was 90.7%, the ammonia-nitrogen content of the filtrate B was 3311 ppm, and the rare earth content was 875 ppm.

[0112] Comparative Example 2

[0113] The sample was prepared according to Patent CN1208134C.

[0114] The calcined molecular sieve prepared in Comparative Example 1, deionized water and the filtrate B described in Comparative Example 1 were mixed and slurried to produce a molecular sieve-containing slurry having a molecular sieve content of 120 g / L, wherein the amount of salt (i.e., the lanthanum chloride, sodium chloride and ammonium chloride contained in the filtrate B used) was 1.0 wt% of the molecular sieve. The resulting molecular sieve slurry was heated to 80°C and poured into a Buchner funnel while the filter flask was evacuated to 0.07 MPa, forming a filter cake having a thickness of 10 mm on the filter cloth. When no liquid was present on the surface of the filter cake, a mixed solution of ammonium chloride having a concentration of 100 g / L and a temperature of 70°C was immediately added at a rate that ensured that no cracks formed on the surface of the filter cake, and the amount of the mixed solution of ammonium chloride was such that the weight ratio of ammonium chloride to molecular sieve was 0.10. When no liquid was present on the surface of the filter cake, deionized water having a temperature of 70°C was immediately added to wash the filter cake, and the weight ratio of deionized water to molecular sieve was 5. The filter cake was then removed and the filtrate C was collected, and the filter cake was dried at 120°C to produce a rare earth Y-type molecular sieve D2. The sodium oxide content of the D2 molecular sieve sample was 0.9%, the rare earth content was 13.7%, the rare earth utilization rate was 90.6%, the ammonia-nitrogen content of the filtrate C was 3288 ppm, and the rare earth content was 973 ppm.

[0115] Comparative Example 3

[0116] 1) NaY zeolite was mixed with water to make a zeolite slurry with a zeolite content of 180 g / L, and oxalic acid was added to adjust the pH value to 8.9. The obtained zeolite slurry was heated to 80°C and poured into a Buchner funnel, and the filter bottle was simultaneously vacuumed to 0.07 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0117] 2) NaY zeolite was mixed with an ammonium-containing filtrate (filtrate B of Comparative Example 1) and lanthanum chloride to make a zeolite slurry, the mass of the ammonium-containing filtrate being 5 times that of the NaY zeolite, and the amount of lanthanum chloride added was such that the mass ratio of lanthanum oxide to zeolite was 0.15. The obtained zeolite slurry was heated to 70°C and stirred for 1 h, and then poured onto the NaY filter cake of step 1) in a Buchner funnel, and the filter bottle was simultaneously vacuumed to 0.07 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0118] 3) When there was no liquid on the surface of the filter cake, deionized water at a temperature of 80°C was immediately added to wash the filter cake, and the weight ratio of deionized water to zeolite was 5. Then the filter cake was removed and the filtrate D was collected, and the filter cake was dried at 120°C and calcined at 600°C for 2 h to obtain a calcined zeolite.

[0119] 4) The calcined zeolite was mixed with water to make a zeolite slurry with a zeolite content of 110 g / L, and the obtained zeolite slurry was heated to 60°C and poured into a Buchner funnel, and the filter bottle was simultaneously vacuumed to 0.06 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0120] 5) When there was no liquid on the surface of the filter cake of step 4) above, an ammonium chloride solution was immediately added at a speed that ensured that no cracks were formed on the surface of the filter cake, and the amount of ammonium chloride added was such that the weight ratio of ammonium chloride to zeolite was 0.10. When there was no liquid on the surface of the filter cake, deionized water at a temperature of 90°C was immediately added to wash the filter cake, and the weight ratio of deionized water to zeolite was 5. Then the filter cake was removed and the filtrate E was collected to obtain a zeolite sample D3, which had a sodium oxide content of 1.2%, a rare earth content of 16.7%, a rare earth utilization rate of 92.7%, an ammonia nitrogen content of 126 ppm, and a rare earth content of 275 ppm in the filtrate D.

[0121] Example 1

[0122] 1) NaY zeolite was mixed with water to make a zeolite slurry with a zeolite content of 180 g / L, and oxalic acid was added to adjust the pH value to 8.9. The obtained zeolite slurry was heated to 80°C and poured into a Buchner funnel, and the filter bottle was simultaneously vacuumed to 0.07 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0123] 2) The NaY molecular sieve is mixed with the ammonium-containing filtrate (filtrate B of Comparative Example 1) and lanthanum chloride. The ammonium-containing filtrate is 5 times the mass of the NaY molecular sieve, and the amount of lanthanum chloride is added so that the mass ratio of lanthanum oxide to molecular sieve is 0.15. The obtained molecular sieve slurry is heated to 70°C and stirred for 1 h, and then poured onto the NaY filter cake of step 1) in a Buchner funnel. The filter bottle is simultaneously vacuumed to 0.07 MPa, and a filter cake with a thickness of 10 mm is formed on the filter cloth.

[0124] 3) When there is no liquid on the surface of the filter cake, deionized water at a temperature of 80°C is immediately added to wash the filter cake. The weight ratio of deionized water to molecular sieve is 5. Then the filter cake is removed and the filtrate F is collected. The filter cake is dried at 120°C and calcined at 600°C for 2 h to obtain a calcined molecular sieve.

[0125] 4) The calcined molecular sieve is mixed with water to prepare a molecular sieve slurry with a molecular sieve content of 110 g / L. The obtained molecular sieve slurry is heated to 60°C and poured into a Buchner funnel. The filter bottle is simultaneously vacuumed to 0.06 MPa, and a filter cake with a thickness of 10 mm is formed on the filter cloth.

[0126] 5) When there is no liquid on the surface of the filter cake of step 4) above, an ammonium chloride solution is immediately added at a speed that ensures that no cracks are formed on the surface of the filter cake. The amount of ammonium chloride is added so that the weight ratio of ammonium chloride to molecular sieve is 0.10. When there is no liquid on the surface of the filter cake, deionized water at a temperature of 90°C is immediately added to wash the filter cake. The weight ratio of deionized water to molecular sieve is 5. Then the filter cake is removed and the filtrate G (with an ammonia nitrogen content of 1475 ppm) is collected to obtain a molecular sieve sample S1. The sodium oxide content of the molecular sieve sample S1 is 0.9%, the rare earth content is 17.9%, the rare earth utilization rate is 99.8%, the ammonia nitrogen content of the filtrate F is 18 ppm, and the rare earth content is 3 ppm.

[0127] Example 2

[0128] The operation steps are the same as in Example 1, except that in step 1), the NaY molecular sieve slurry has a content of 300 g / L, the mass ratio of oxalic acid to NaY molecular sieve is 0.03, citric acid is added to adjust the pH to 10, the slurry temperature is 15°C, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 5 mm.

[0129] Step 2) The NaY molecular sieve is mixed with the ammonium-containing filtrate (filtrate G) and cerium nitrate. The amount of filtrate G is 2 times the mass of the NaY molecular sieve, and the mass ratio of cerium oxide to molecular sieve is 0.12. The slurry temperature is 50°C, stirring is performed for 2 h, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 15 mm.

[0130] Step 3) The deionized water temperature is 100°C, and the weight ratio of deionized water to molecular sieve is 1. The filtrate H is collected, the filter cake is dried at a temperature of 200°C, and calcination is performed at a temperature of 500°C for 3 h.

[0131] Step 4) The slurry of the calcined molecular sieve has a molecular sieve content of 300 g / L, the slurry temperature is 80°C, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 5 mm.

[0132] Step 5) The weight ratio of ammonium chloride to the molecular sieve is 0.25, the deionized water temperature is 20°C, and the weight ratio of the deionized water to the molecular sieve is 15. Then the filter cake is removed and the filtrate I (with an ammonia nitrogen content of 3176 ppm) is collected, to obtain the molecular sieve sample S2, which has a sodium oxide content of 1.1%, a rare earth content of 11.9%, a rare earth utilization rate of 99.2%, an ammonia nitrogen content of the filtrate H of 16 ppm, and a rare earth content of 6 ppm.

[0133] Example 3

[0134] The operation steps are the same as those in Example 1, wherein step 1) the slurry of the NaY molecular sieve has a content of 100 g / L, the mass ratio of the phthalic acid to the NaY molecular sieve is 0.01, hydrochloric acid is added to adjust the pH to 6, the slurry temperature is 100°C, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 15 mm.

[0135] Step 2) The NaY molecular sieve is mixed with the ammonium-containing filtrate (filtrate I) and yttrium chloride to form a slurry, the amount of the filtrate I is 10 times that of the NaY molecular sieve, the mass ratio of yttrium oxide to the molecular sieve is 0.35, the slurry temperature is 100°C, the stirring time is 0.5 h, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 5 mm.

[0136] Step 3) The deionized water temperature is 20°C, and the weight ratio of the deionized water to the molecular sieve is 15. The filtrate J is collected, the filter cake is dried at a temperature of 20°C, and the calcination temperature is 800°C and the calcination time is 1 h.

[0137] Step 4) The slurry of the calcined molecular sieve has a molecular sieve content of 100 g / L, the slurry temperature is 20°C, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 20 mm.

[0138] Step 5) The weight ratio of ammonium carbonate to the molecular sieve is 0.10, the deionized water temperature is 100°C, and the weight ratio of the deionized water to the molecular sieve is 15. Then the filter cake is removed and the filtrate K (with an ammonia nitrogen content of 773 ppm) is collected, to obtain the molecular sieve sample S3, which has a sodium oxide content of 1.0%, a rare earth content of 34.8%, a rare earth utilization rate of 99.5%, an ammonia nitrogen content of the filtrate J of 14 ppm, and a rare earth content of 7 ppm.

[0139] Example 4

[0140] The operation steps are the same as those in Example 1, wherein step 1) the slurry of the NaY molecular sieve has a content of 180 g / L, the mass ratio of the phthalic acid to the NaY molecular sieve is 0.15, sulfuric acid is added to adjust the pH to 7, the slurry temperature is 75°C, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 8 mm.

[0141] Step 2) NaY molecular sieve is mixed with the filtrate containing ammonium salt (filtrate K), lanthanum chloride and cerium nitrate, the amount of filtrate G is 4 times of the NaY molecular sieve, the mass ratio of lanthanum oxide, cerium oxide and molecular sieve is 0.10:0.10:1, the slurry temperature is 70°C, the stirring time is 1.5h, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 13mm.

[0142] Step 3) The temperature of deionized water is 40°C, and the weight ratio of deionized water to molecular sieve is 8. The filtrate L is collected, the drying temperature of the filter cake is 60°C, the calcination temperature is 600°C, and the calcination time is 1.5h.

[0143] Step 4) The slurry of the calcined molecular sieve has a molecular sieve content of 170g / L, the slurry temperature is 60°C, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 18mm.

[0144] Step 5) The weight ratio of ammonium sulfate to molecular sieve is 0.17, the temperature of deionized water is 60°C, and the weight ratio of deionized water to molecular sieve is 9. After the filter cake is dried at 200°C, it is calcined at 500°C for 1h, then the filter cake is removed and the filtrate M (ammonia nitrogen content is 2651ppm) is collected, to obtain a molecular sieve sample S4, which has a sodium oxide content of 1.2%, a rare earth content of 19.9%, a rare earth utilization rate of 99.8%, an ammonia nitrogen content of the filtrate L of 14ppm, and a rare earth content of 2ppm.

[0145] From the results of examples 1 to 4, it can be seen that the rare earth Y-containing molecular sieve obtained by the method of the present application has higher rare earth utilization rate and lower ammonia nitrogen content in the filtrate than the conventional rare earth Y-containing molecular sieve. Compared with the molecular sieves D1 and D2 prepared in the comparative examples, the molecular sieves prepared in the examples have sodium oxide content comparable to that of the comparative molecular sieves, but in the process of preparing the molecular sieves, there is basically no loss of rare earth, the rare earth utilization rate is more than 99%, and the ammonia nitrogen content in the filtrate is less than 20 ppm. The molecular sieve prepared by using comparative example D1 has a rare earth content in the molecular sieve obviously lower than the feeding amount, and a large amount of rare earth is not exchanged onto the molecular sieve in the exchange and is lost with the filtrate in the filtration process, resulting in low utilization rate of the rare earth and environmental pollution caused by the rare earth in the filtrate if not treated. Compared with comparative example D2, the present application introduces a layer of NaY molecular sieve treated with humic acid at the bottom of the molecular sieve rare earth and ammonium ion exchange filter cake, which can significantly improve the utilization rate of rare earth and ammonium salt in the molecular sieve exchange process and reduce the loss of rare earth and ammonia nitrogen. From examples 1 and 2, it can be seen that comparative example 2 recovers part of the rare earth ions and ammonium ions by beating with the filtrate containing rare earth and ammonium, and the rare earth and ammonia nitrogen content in the filtrate is high and cannot meet the direct discharge requirement. From examples 1 and 3, it can be found that the addition of humic acid can improve the utilization rate of rare earth and ammonium in the molecular sieve exchange process, and the rare earth and ammonia nitrogen content in the filtrate is further reduced. Therefore, the rare earth Y-containing molecular sieve prepared by the method provided by the present application can balance the rare earth utilization rate and the sodium oxide content of the molecular sieve, and the ammonia nitrogen content in the filtrate is low, no ammonia nitrogen treatment is required, and the subsequent use of the molecular sieve is not affected, which has good industrial application prospect.

[0146] Of course, the present application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications should all belong to the protection scope of the claims of the present application.

Claims

1. A method for preparing rare earth-containing Y-type molecular sieves, characterized in that, Includes the following steps: S1, NaY molecular sieve, humic acid and water are slurried, filtered to form NaY molecular sieve filter cake; S2, mix and slurry NaY molecular sieve, rare earth salt and ammonium salt solution to obtain RE-NaY cross molecular sieve slurry, place RE-NaY cross molecular sieve slurry on NaY molecular sieve filter cake, filter to obtain RE-NaY cross molecular sieve composite filter cake, wash RE-NaY cross molecular sieve composite filter cake with water, dry and calcine to obtain calcined molecular sieve; S3, after mixing a molecular sieve with water and filtering it to obtain a filter cake, the filter cake is then exchanged with an ammonium salt solution and washed with water to obtain a rare earth Y-type molecular sieve.

2. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The slurry after pulping in step S1 is adjusted to pH 6-10 with acid and then filtered. The acid is one or more of oxalic acid, citric acid, phosphoric acid, hydrochloric acid, sulfuric acid, and nitric acid.

3. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The slurry after pulping in step S1 is adjusted to pH 7-9 with acid and then filtered. The acid is oxalic acid and / or citric acid.

4. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, In step S1, the dry weight ratio of humic acid to NaY molecular sieve is 0.01~0.03:1, and the humic acid is one or more of fulvic acid, brown humic acid and black humic acid.

5. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, In step S2, the rare earth salt, calculated as rare earth oxides, has a weight ratio of 0.12 to 0.35:1 with NaY molecular sieve, and the ammonium salt solution, calculated by solution mass, has a weight ratio of 3 to 6:1 with NaY molecular sieve. The pulping temperature is 50 to 100°C, the pulping time is 0.5 to 2 hours, and the ammonia nitrogen content in the ammonium salt solution is 500 to 3500 ppm.

6. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, In step S2, the ammonium salt solution has a weight ratio of 3 to 6:1 with NaY molecular sieve, based on the mass of the solution.

7. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, In step S3, the weight ratio of ammonium salt to 1-baked molecular sieve is 0.1~0.25:

1.

8. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The sodium oxide content of the NaY molecular sieve is 9-15%.

9. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The rare earth salt is a nitrate or chloride salt of rare earth elements, and the rare earth elements are one or more of lanthanum, cerium, praseodymium, neodymium, and yttrium.

10. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The ammonium salt mentioned in step S2 and the ammonium salt mentioned in step S3 are each independently one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate and ammonium bicarbonate.

11. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The ammonium salt mentioned in step S2 and the ammonium salt mentioned in step S3 are each independently ammonium chloride and / or ammonium sulfate.

12. The method for preparing rare earth Y-type molecular sieves according to claim 1, characterized in that, The filtrate from the RE-NaY-cross molecular sieve composite filter cake formed in step S2 and the exchange liquid obtained from ion exchange in step S3 are recycled as the ammonium salt solution in step S2.

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