Method and device for ammonium ion exchange of y-type molecular sieve

Abstract

The application provides an ammonium ion exchange method and device of Y-type molecular sieve, and the method comprises the following steps: step 1, forming a NaY molecular sieve filter cake layer by using a slurry of NaY molecular sieve; step 2, mixing and beating the NaY molecular sieve with an ammonium salt solution to form an NH-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, and obtaining a composite filter cake; and step 3, performing ion exchange on the composite filter cake obtained in step 2 by using the ammonium salt solution, and performing calcination to obtain ammonium-exchanged Y-type molecular sieve. The Y-type molecular sieve ammonium ion exchange method provided by the application realizes high utilization of ammonium salt in the NaY molecular sieve exchange process by using NaY filter cake layers and humic acid to recover the lost ammonium in the filtrate.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve materials and their preparation, specifically to a method and apparatus for ammonium ion exchange of Y-type molecular sieves. Background Technology

[0002] As we all know, the petroleum refining industry is an important pillar of the national economy, with a long industrial chain, a wide range of products, and close ties to people's lives. One of the most important refining methods in the petroleum refining process is catalytic cracking technology. 70% of the gasoline, 40% of the diesel, and 35% of the propylene needed in my country come from catalytic cracking, and the catalytic cracking catalyst is the core component of catalytic cracking.

[0003] To reduce the sodium oxide content in catalysts, which significantly impacts catalytic activity, selectivity, and stability, semi-synthetic molecular sieve catalysts typically employ ammonium ion exchange to lower the sodium oxide content. To enhance the sodium ion exchange rate, multiple ammonium exchange processes, washing, and intermediate roasting are often used. However, the extensive use of ammonium salts results in substantial amounts of ammonia nitrogen wastewater and exhaust gas, increasing production costs and wastewater treatment burdens, as well as the investment and maintenance costs of ammonia nitrogen removal equipment. Furthermore, ammonia nitrogen exchanged or adsorbed on the molecular sieve or catalyst is released into the atmosphere during intermediate roasting, contributing to air pollution. Therefore, reducing production costs and addressing ammonia nitrogen pollution during catalyst preparation are key priorities and challenges in the development of catalytic cracking catalysts.

[0004] CN103240113A discloses a method for preparing an in-situ crystallization catalyst to reduce ammonia nitrogen pollution. The method involves adding polydimethyldiallyl ammonium chloride, which can modulate the inter-kaolin packing pattern, during spraying. After obtaining the in-situ crystallization product, the exchange environment of the exchange ions is first cleaned with an acidic solution, followed by other exchange and calcination steps to obtain a catalytic cracking catalyst. This method can reduce the amount of ammonium salt used by more than 15%, effectively alleviate the ammonia nitrogen pollution problem in the preparation process of the in-situ crystallization catalyst, reduce production costs, and improve the catalyst's reaction performance.

[0005] CN100404432C discloses a method for reducing ammonia nitrogen pollution during zeolite modification. The method involves exchanging sodium in the zeolite with potassium compounds during the modification process, followed by further zeolite exchange modification with ammonium salts. This method does not increase the cost of zeolite modification, reduces the amount of ammonium salt used by approximately 50%, thereby reducing ammonia nitrogen pollution and the burden and investment in ammonia nitrogen wastewater treatment. It is an environmentally friendly technology for modifying zeolite. The prepared zeolite and catalyst have a lower sodium oxide content, while the catalyst performance remains essentially unchanged or is improved.

[0006] CN103028431A discloses a clean production process for molecular sieve catalytic cracking catalysts. This method uses a conventional in-situ crystallization method to prepare modified molecular sieves or molecular sieve catalytic cracking catalysts. The mother liquor from molecular sieve crystallization filtration and / or the washing water from the crystallization material is mixed with ammonia nitrogen wastewater generated during the molecular sieve exchange process and used as the scrubbing liquid in a scrubbing tower for the catalyst spray granulation tail gas. Aluminum chloride or acid is added to the above-mentioned scrubbing liquid, which is then gelled, filtered, and the filtrate is discharged. The filter residue is used as raw material for synthesizing molecular sieves. This method, while producing qualified catalytic cracking catalyst products, allows the high ammonia nitrogen content wastewater generated during the process to directly meet discharge standards at very low operating costs, and the silicon compounds in the wastewater can be fully recovered and recycled.

[0007] While the methods described above significantly reduce ammonia nitrogen wastewater during catalytic cracking, they still introduce ammonium ions to varying degrees, failing to achieve ammonia-free production. The ammonia nitrogen content in the filtrate from the ammonium exchange step can reach 4000-10000 mg / kg, and even the ammonia nitrogen content in the wash water can reach 150-1500 mg / kg. However, the national standard "Integrated Wastewater Discharge Standard" requires ammonia nitrogen levels of 15 mg / kg for primary discharge and 50 mg / kg for secondary discharge. Therefore, with the implementation of the new Environmental Protection Law and the increasing environmental awareness of citizens, there is an urgent need to develop new technologies for preparing catalytic cracking catalysts that are simple in process, low in cost, and ammonia-free in production.

[0008] Patent CN102795636B discloses an exchange modification method for reducing the sodium oxide content in Y-type molecular sieves. The method involves contacting a Y-type molecular sieve with a high Na content with an aqueous solution containing inorganic and organic acids at 0-5°C for 0.5-3 hours, followed by separation, washing, and drying to obtain a Y-type molecular sieve with a lower sodium oxide content. The weight ratio of H₂O to molecular sieve is 11-18:1. This method significantly reduces the sodium oxide content in Y-type molecular sieves without using ammonium salts, eliminating ammonia nitrogen pollution at its source. It also significantly reduces water consumption and wastewater discharge during the Y-type molecular sieve exchange process.

[0009] Patent CN102557070B discloses a method for sodium removal via exchange using organic carboxylic acids during the preparation of Y-type molecular sieves. The method involves mixing NaY molecular sieves, organic carboxylic acids, and a dispersion medium, followed by stirring, filtration, washing, and drying to obtain NaHY molecular sieves. The organic carboxylic acid is acetic acid. The raw material ratio is acetic acid / NaY molecular sieve = 0.15-0.6 mmol / g, and dispersion medium / NaY molecular sieve = 5-200 (w / w). This invention avoids the introduction of inorganic ammonium salts as byproducts, reduces unnecessary inorganic salt byproducts generated during the exchange process, and mitigates the environmental impact of nitrogen-containing wastewater discharge.

[0010] Patent CN102794191A discloses a novel ammonia-free method for preparing catalytic cracking catalysts. In this method, the exchange process between the molecular sieve and the catalyst is carried out in a mixed acid solution of inorganic and organic acids at low temperature and low acid concentration. This method reduces the sodium oxide content in the catalyst, avoids ammonia nitrogen pollution during the molecular sieve exchange and catalyst washing processes, and significantly reduces water consumption and wastewater treatment costs. However, a drawback is that while using inorganic and organic acids to exchange and wash the molecular sieve and catalyst to reduce sodium, it also significantly damages the crystal structure of the molecular sieve, resulting in poor crystallinity of the molecular sieve in the catalyst and reducing its thermal and hydrothermal stability.

[0011] Patent CN1840614A describes a method that involves contacting one or more of dried NaY, RENaY, REHY, or REY molecular sieves with silicon tetrachloride at a weight ratio of silicon tetrachloride:Y-type molecular sieve = 0.1-0.9:1 at 100-600℃ for 10 minutes to 6 hours. After the gas-phase ion exchange reaction, over 90% of the sodium oxide in the Y-type molecular sieve is removed. The reacted Y-type molecular sieve is then directly mixed with a binder and clay to form a slurry. After spray molding, washing, filtration, and drying, the final catalytic cracking catalyst is obtained. The disadvantages of this method are that during the gas-phase ion exchange of the rare earth-containing Y-type molecular sieve, a significant amount of rare earth ions are exchanged by silicon tetrachloride, reducing the utilization rate of rare earths. Furthermore, the direct mixing and spraying of the molecular sieve with other raw materials after sodium reduction and stabilization without a washing and exchange step can lead to the removal of harmful ions, such as Na+, during the gas-phase ion exchange process. + NH4 + SO4 2- Ions and other particles re-enter the molecular sieve and catalyst.

[0012] CN102553630A describes the preparation of NaY molecular sieve microspheres using a traditional in-situ crystallization method. These microspheres are then contacted with silicon tetrachloride gas at a weight ratio of 0.1-0.9:1 at 150-500℃ for 10 minutes to 6 hours. The resulting in-situ crystallized NaY zeolite microspheres are then washed with deionized water at 20-100℃ to remove residual Na. + Cl - Al 3+ Soluble byproducts are used to prepare catalytic cracking catalysts with Y-type molecular sieves containing small crystals with high silicon-to-aluminum ratios. However, this method still cannot avoid the drawbacks of in-situ crystallization technology being difficult, production costs being high, and difficulty in reducing sodium content in molecular sieves or catalysts.

[0013] Patent CN106732745B discloses a method for preparing a catalytic cracking catalyst. This method involves contacting NaY molecular sieve powder with a halogen-containing gas to carry out a gas-phase ion exchange reaction, thereby completing the sodium reduction and ultrastabilization of the NaY molecular sieve powder in one step to obtain a low-sodium, high-silicon-alumina ratio molecular sieve. The method also involves compounding different types of clay ore and treating them with high-concentration acid to obtain acid-activated composite clay. The low-sodium, high-silicon-alumina ratio molecular sieve, acid-activated composite clay, binder, rare earth elements, and decationized water are then mixed, slurried, spray-granulated, and calcined to solidify, without the need for washing or drying, to obtain the finished catalytic cracking catalyst.

[0014] The gas-phase ion exchange reaction of silicon tetrachloride involves contact reaction in a specific gas-phase reactor with silicon tetrachloride gas, or silicon tetrachloride gas that has not been diluted by a carrier gas. Silicon tetrachloride hydrolyzes to produce silica gel and hydrochloric acid. Silica gel easily clogs pipes, while hydrochloric acid is extremely damaging to equipment and molecular sieves. Therefore, the molecular sieve raw material needs to be pre-dried and dehydrated at 400-600℃ before the reaction to achieve gas-phase exchange and sodium reduction. After the reaction, the molecular sieve, with or without washing, is mixed with binder, clay, and decationized water, slurried, and spray-molded. After washing and drying, a catalytic cracking catalyst is obtained. However, no effective treatment method has been provided for the high-salt waste liquid that absorbs silicon tetrachloride tail gas, and it is even directly discharged, which causes significant environmental pollution.

[0015] There are two industrial methods for ion exchange using NaY molecular sieves: The first method involves mixing the Y-type molecular sieve with an aqueous solution containing rare earth ions to form a slurry, followed by ion exchange, filtration, washing, drying, and calcination (or no calcination). A plate and frame filter press is used for filtration. The disadvantages of this method are low efficiency and high water consumption. The second method involves mixing the Y-type molecular sieve with water to form a Y-type molecular sieve slurry. This slurry is directly transferred onto the filter cloth of a belt filter, forming a filter cake of a certain thickness. An aqueous solution of ammonium ions and / or rare earth ions is then added from above the filter cake. Under vacuum in the liquid receiver below the filter cloth, the solution containing ammonium ions and / or rare earth ions continuously passes through the filter cake, resulting in ion exchange. Belt filters are energy-efficient and highly effective, and are widely used in large-scale industrial production.

[0016] US3943233 discloses a method for continuous ion exchange of fluidizable zeolite particles. The method includes slurrying the zeolite particles with a first liquid, loading the slurry at a substantially constant rate into the feed end of a continuous horizontal belt vacuum filter, continuously moving the filter belt containing the slurry through a cake forming zone, at least one ion exchange zone, and a washing zone, while simultaneously applying vacuum to liquid receivers under each independent filter belt, and unloading the filter cake from the filter belt. The method is characterized by the filter cake leaving the cake forming zone with substantially no surface cracks, but containing liquid within the voids of the fluidizable zeolite particles. During the ion exchange process, the filter cake, in the ion exchange zone, contacts an ion exchange liquid under filtration conditions, leaves the ion exchange zone as a smooth, substantially crack-free filter cake containing liquid within the voids of the fluidizable zeolite particles, and is rapidly washed under vacuum after ion exchange.

[0017] CN1142024C discloses a method for rare earth ion exchange using a molecular sieve. The method includes slurrying a molecular sieve with water, continuously transferring the resulting slurry onto the filter belt of a horizontal belt vacuum filter, sequentially passing it through a cake forming zone and an ion exchange zone, applying vacuum to liquid receivers under the filter belt in both the cake forming and ion exchange zones, washing and drying the filter cake, and removing the filter cake from the filter belt. The method is characterized by the molecular sieve being a Y-type chelate-battery molecular sieve, the addition of acid and / or salt to the slurry (the amount of acid or salt being 0.1-5% by weight of the molecular sieve), the vacuum level in the liquid receiver of the cake forming zone ensuring that the filter cake surface is essentially free of cracks, and the addition of a rare earth ion-containing solution to the upper part of the filter cake in the ion exchange zone, the concentration of the rare earth ion-containing solution being such that the weight ratio of rare earth oxides to the molecular sieve is 0.01-0.5%.

[0018] CN1485136A describes a method for continuously loading a molecular sieve-containing slurry with a pH of 2-7 onto the filter cloth of a horizontal belt filter. The filter cloth loaded with the molecular sieve slurry is sequentially passed through a cake forming zone, an ion exchange zone, and a washing zone. It is then blotted dry, unloaded, and dried to obtain the exchanged molecular sieve filter cake. In the ion exchange zone, an aqueous solution of rare earth compounds at a temperature of 10-100℃ is added from the top of the filter cake. The amount of rare earth compound aqueous solution used is such that the weight ratio of rare earth oxides to molecular sieves is 0.01-0.2.

[0019] In existing technologies, after ammonium ion exchange using molecular sieves, the ion exchange process typically involves filtration and washing. This results in incomplete exchange of ammonium ions onto the molecular sieve, with some ions being lost into the filtrate, leading to low ammonium ion utilization. Furthermore, the aforementioned molecular sieve belt filter exchange patent only provides an ion exchange method for molecular sieves and does not address the technical issues of improving ammonium ion utilization during the ion exchange process.

[0020] Currently, the main industrial technologies for treating high concentrations of ammonia nitrogen in wastewater, both domestically and internationally, include alkali stripping or steam stripping, membrane separation, and biochemical denitrification. While stripping technology is relatively mature, it suffers from high operating costs, severe equipment corrosion, and requires significant energy and alkali consumption when the water is acidic, making it economically unfeasible. Furthermore, while adsorption-exchange, chemical precipitation, and electrochemical methods have been extensively documented, they all suffer from drawbacks such as high investment costs, complex operation, and high operating expenses.

[0021] Patent CN8610692A uses natural clinoptilolite or mordenite as the main raw material, adds a certain amount of aluminum hydroxide, potassium chloride, sodium hydroxide and water, mixes and crystallizes for a long time to synthesize an adsorbent for treating ammonia nitrogen wastewater.

[0022] Patent CN1485281A uses 13X molecular sieve to treat ammonia nitrogen wastewater, and the molecular sieve is regenerated using a 20% sodium chloride solution.

[0023] Patent CN1274406C describes an adsorbent prepared by mixing NaY molecular sieve with aluminum hydroxide dry gel powder, guar gum powder, organic acid and inorganic acid to remove ammonia nitrogen from wastewater in a fixed bed configuration. The adsorbent is regenerated using a 1-20% sodium carbonate solution, and its adsorption capacity can be restored to more than 90%.

[0024] Patent CN1840482A describes a method for treating ammonia-nitrogen-containing industrial wastewater by contacting it with a gel in a molar ratio of rNa₂O:Al₂O₃:xSiO₂:yX:zH₂O, where r = 0.01-2, x = 3-11, y = 0.01-3, z = 0-500, and X is one or more elements selected from acids, oxides, or other elements. The contact method involves either co-slurrying the wastewater with the gel followed by filtration or adsorption using an adsorption bed.

[0025] Patent CN101007261A describes a process of mixing 60-95% zeolite with 30% filler, 1-30% binder, 0-20% pore-forming agent, and 0-20% acid, spray granulating, and calcining to produce 20-500μm powder particles for treating ammonia nitrogen wastewater, with a pore volume greater than 0.5ml / g.

[0026] In summary, to reduce ammonia nitrogen wastewater discharge and environmental pollution, existing technologies all employ adsorbents to adsorb ammonia nitrogen and meet emission standards. This operation requires prolonged contact between the adsorbent and the wastewater, and the adsorbent needs periodic regeneration. This cannot meet the continuous production requirements of the molecular sieve preparation process, severely impacting the production capacity of molecular sieves.

[0027] Therefore, how to effectively improve the ammonium ion utilization rate in the ion exchange process of Y-type molecular sieve belt filters and reduce ammonia nitrogen wastewater discharge is an important measure for molecular sieve manufacturers to reduce costs and increase efficiency, and it is also one of the key research topics for molecular sieve manufacturers. Summary of the Invention

[0028] The main objective of this invention is to provide a method and apparatus for ammonium ion exchange using Y-type molecular sieves, in order to solve the problem of severe ammonia nitrogen pollution in the existing technology of ammonium ion exchange using Y-type molecular sieves.

[0029] To achieve the above objectives, the present invention provides an ammonium ion exchange method using a Y-type molecular sieve, comprising the following steps:

[0030] Step 1: Form a NaY molecular sieve filter cake layer from the NaY molecular sieve slurry;

[0031] Step 2: Mix NaY molecular sieve with ammonium salt solution and slurry to form NH-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, and obtain composite filter cake;

[0032] Step 3: The ammonium salt solution is subjected to ion exchange with the composite filter cake obtained in Step 2, followed by calcination to obtain an ammonium-exchanged Y-type molecular sieve.

[0033] The ammonium ion exchange method for Y-type molecular sieves of the present invention includes the addition of humic acid to the slurry of NaY molecular sieve in step 1. The humic acid is selected from fulvic acid, brown humic acid, black humic acid or a mixture thereof, and the dry weight ratio of the humic acid to the NaY molecular sieve in step 1 is 0.001-0.05:1.

[0034] The ammonium ion exchange method for Y-type molecular sieves of the present invention, wherein the mass ratio of ammonium salt solution to dry NaY molecular sieve in step 2 is 2-10:1, the pulping temperature in step 2 is 50-100℃, and the pulping time is 0.5-2 hours.

[0035] The ammonium ion exchange method for Y-type molecular sieves of the present invention, wherein, in step 3, the ammonium salt solution is added from the top of the composite filter cake and flows through the composite filter cake to perform ion exchange; the weight ratio of the ammonium salt solution in step 3 to the dry basis of NaY molecular sieve in step 2 is 0.05-0.25:1, calculated as ammonium salt.

[0036] The ammonium ion exchange method for Y-type molecular sieves of the present invention further includes step 4, which involves mixing the Y-type molecular sieve calcined in step 3 with water to form a filter cake, performing a secondary ion exchange with the filter cake containing an ammonium salt solution, and then performing a secondary calcination to obtain an ammonium-exchanged Y-type molecular sieve.

[0037] The ammonium ion exchange method for Y-type molecular sieves of the present invention, wherein the ammonium salt solution is calculated as ammonium salt, and the weight ratio of the ammonium salt solution in step 4 to the Y-type molecular sieve after calcination in step 3 is 0.02-0.25:1.

[0038] The ammonium ion exchange method for Y-type molecular sieves of the present invention, wherein the ammonium salt in the ammonium salt solution in step 2 and the ammonium salt solution in step 3 is independently one of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate, and ammonium bicarbonate.

[0039] The ammonium ion exchange method for Y-type molecular sieves of the present invention includes the following steps: the filtrate for forming the NH-NaY molecular sieve filter cake layer in step 2 and the exchange solution obtained from ion exchange in step 3 are recycled as the ammonium salt solution in step 2.

[0040] The ammonium ion exchange method for Y-type molecular sieves of the present invention, wherein, in step 1, the content of NaY molecular sieve in the NaY molecular sieve slurry is 100-300 g / L.

[0041] To achieve the above objectives, the present invention also provides an apparatus for ammonium ion exchange of Y-type molecular sieves. The apparatus includes a horizontal belt filter, which comprises a NaY filter cake forming zone, a composite filter cake forming zone, and an ion exchange zone. The NaY filter cake forming zone is used to form a NaY filter cake layer, the composite filter cake forming zone is used to form an NH-NaY filter cake layer on the NaY filter cake layer, and the ion exchange zone is used for ion exchange between the ammonium salt solution and the composite filter cake.

[0042] The beneficial effects of this invention are:

[0043] (1) The Y-type molecular sieve ammonium ion exchange method provided by this invention first forms a NaY molecular sieve filter cake layer, and then loads the ammonium-exchanged Y molecular sieve onto the NaY molecular sieve filter cake layer to form an NH-NaY molecular sieve filter cake layer. In this way, the excess ammonium ions in the upper filtrate can be recovered by utilizing the adsorption properties of the NaY filter cake layer. At the same time, the excess ammonium ions can also exchange part of the NaY molecular sieve Na in the NaY molecular sieve layer. + Effectively removes Na from the NaY molecular sieve layer + The adsorption and ion exchange properties of NaY molecular sieves can recover ammonium ions lost from the filtrate, thus enabling the effective utilization of ammonium salts.

[0044] (2) The humic acid added to the NaY molecular sieve slurry in this invention is a multi-component organic complex that dissolves in the NaY molecular sieve system to form sodium humate. Sodium humate can restrict the migration of ammonium ions in the filtrate through adsorption and exchange, thus inhibiting the loss of ammonium ions with the filtrate.

[0045] (3) The Y-type molecular sieve ammonium ion exchange method provided by this invention recovers the ammonium lost from the filtrate through the adsorption of NaY filter cake layer and humic acid, achieving zero loss of ammonium salts during the NaY molecular sieve exchange process. Therefore, compared with the prior art, the Y-type molecular sieve ammonium ion exchange method provided by this invention can exchange Na in the molecular sieve. +This method enables 100% utilization of ammonium salts. Furthermore, the Y-type molecular sieve ammonium ion exchange method provided by this invention is simple and achieves zero ammonia nitrogen wastewater discharge during the molecular sieve exchange process, promoting continuous molecular sieve production and energy conservation and emission reduction for enterprises. Attached Figure Description

[0046] Figure 1 This is a flowchart of the molecular sieve exchange process of the present invention;

[0047] Figure 2 This is a flowchart of the molecular sieve two-stage exchange process of the present invention.

[0048] In the attached figures, the following labels are used:

[0049] 1,5,15 Pulping Tank

[0050] Pipelines 2, 6, 10, 13, 16, 20, 24, 26

[0051] 3.17 Filter cloth

[0052] 4 NaY molecular sieve filter cake formation zone

[0053] 7. Molecular sieve filter cake formation zone

[0054] 8.22 Liquid Receiver

[0055] 9,12,19,23 Containers

[0056] 11,21 Ion exchange regions

[0057] 14,25 Washing Area

[0058] 18. Dichroic molecular sieve filter cake formation zone Detailed Implementation

[0059] The technical solution of the present invention will be described in detail below. The following embodiments are implemented under the premise of the technical solution of the present invention and a detailed implementation process is given. However, the protection scope of the present invention is not limited to the following embodiments. Structures or experimental methods that do not specify specific conditions in the following embodiments are generally performed under conventional conditions.

[0060] This invention provides a method for ammonium ion exchange using Y-type molecular sieves, comprising the following steps:

[0061] Step 1: Form a NaY molecular sieve filter cake layer from the NaY molecular sieve slurry;

[0062] Step 2: Mix NaY molecular sieve with ammonium salt solution and slurry to form NH-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, and obtain composite filter cake;

[0063] Step 3: The ammonium salt solution is subjected to ion exchange with the composite filter cake obtained in Step 2, followed by calcination to obtain an ammonium-exchanged Y-type molecular sieve.

[0064] The Y-type molecular sieve ammonium ion exchange method provided by this invention first forms a NaY molecular sieve filter cake layer, and then loads the ammonium-exchanged Y molecular sieve onto the NaY molecular sieve filter cake layer to form an NH-NaY molecular sieve filter cake layer. During the formation of the NH-NaY molecular sieve filter cake layer or in subsequent ion exchange processes, ammonium ions that have not been exchanged by the NH-NaY molecular sieve filter cake layer can be further adsorbed by the NaY filter cake layer due to its ammonium ion adsorption properties. Simultaneously, excess ammonium ions can also exchange some of the Na+ in the NaY molecular sieve when passing through the NaY molecular sieve layer. + Effectively removes Na from the NaY molecular sieve layer + Therefore, the adsorption and ion exchange properties of NaY molecular sieves can further recover the ammonium ions lost from the filtrate, thus achieving the effective utilization of ammonium salts.

[0065] The present invention does not particularly limit the Y-type molecular sieve to be used for ion exchange. In one embodiment, the Y-type molecular sieve of the present invention contains Na. + The present invention relates to a Y-type molecular sieve, namely NaY molecular sieve; in another embodiment, the sodium oxide content in the NaY molecular sieve is 9-15% by mass. NaY molecular sieve and its preparation method are well known to those skilled in the art. For example, the NaY molecular sieve synthesis method provided by patent CN103449468B involves: mixing water glass, sodium aluminate, and deionized water, and aging at 15-70°C for 0.5-48 hours to obtain a crystallization guiding agent; uniformly mixing the crystallization guiding agent, water glass, acidic aluminum salt, and sodium aluminate solution to obtain a silica-alumina gel; crystallizing the silica-alumina gel at 80-140°C for 0.1-80 hours; and adding peroxide to the crystallized silica-alumina gel to allow the O2 in the peroxide to dissolve. 2- The molar ratio of Al2O3 in the gel is 0.05-20, and then crystallization is continued for 5-20 hours to obtain the final product.

[0066] Furthermore, the present invention does not specifically limit the source of NaY molecular sieves; they can be prepared using existing methods or are commercially available.

[0067] This invention first forms a slurry from a portion of the NaY molecular sieve to be ion-exchanged, for example, by pulping the NaY molecular sieve with water. In one embodiment, the pulping conditions for the NaY molecular sieve with water are well known to those skilled in the art; for example, the NaY molecular sieve content in the slurry is generally 100-300 g / L. The pulping temperature can be 10-100°C, preferably 50-90°C.

[0068] Then, the NaY molecular sieve slurry is used to form a NaY molecular sieve filter cake layer. In one embodiment, the thickness of the NaY molecular sieve filter cake layer is 0.5-1.5 cm.

[0069] In one embodiment, humic acid is further added to the slurry of the NaY molecular sieve of the present invention, and the weight ratio of humic acid to the dry basis of the NaY molecular sieve is 0.001-0.05:1. In another embodiment, the humic acid is selected from fulvic acid, brown humic acid, black humic acid, or mixtures thereof.

[0070] The humic acid added to the NaY molecular sieve slurry in this invention is a multi-component organic complex that dissolves in the NaY molecular sieve system to form sodium humate. Sodium humate can restrict the migration of ammonium ions in the filtrate through adsorption and exchange, thus inhibiting the loss of ammonium ions with the filtrate.

[0071] Step 2 is as follows: NaY molecular sieve is mixed with an ammonium salt solution and slurryed to form an NH-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, thus obtaining a composite filter cake.

[0072] Step 2 involves mixing and slurrying the remaining NaY molecular sieve to be ion-exchanged with an ammonium salt solution. The sum of the NaY molecular sieve to be ion-exchanged in Step 1 and the remaining NaY molecular sieve to be ion-exchanged in Step 2 constitutes all the NaY molecular sieve to be ion-exchanged. This invention does not specifically limit the ratio of the partially ion-exchanged NaY molecular sieve to the remaining NaY molecular sieve to be ion-exchanged. In one embodiment, the thickness of the NaY molecular sieve filter cake layer formed by the partially ion-exchanged NaY molecular sieve in Step 1 is 0.5-1.5 cm, and the thickness of the NH-NaY molecular sieve filter cake layer formed by the remaining NaY molecular sieve to be ion-exchanged in Step 2 is 0.5-1.5 cm.

[0073] In one embodiment, the ammonium salt in the ammonium salt solution in step 2 of the present invention is a soluble ammonium salt, that is, an ammonium salt soluble in water. In another embodiment, the ammonium salt of the present invention is one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate, and ammonium bicarbonate, preferably ammonium chloride and ammonium sulfate. Step 2, mixing and pulping the NaY molecular sieve with the ammonium salt solution, allows this portion of the NaY molecular sieve to undergo preliminary ammonium ion exchange. In this step, the mass ratio of the ammonium salt solution to the dry basis of the NaY molecular sieve is 2-10:1, preferably 3-6. The concentration of the ammonium salt in the ammonium salt solution, expressed as nitrogen, is 100-20000 ppm. The pulping temperature is 50-100℃, and the time is 0.5-2 hours.

[0074] Then, the slurry formed in step 2 is applied to the NaY molecular sieve filter cake layer to form an NH-NaY molecular sieve filter cake layer, thus obtaining a composite filter cake.

[0075] Step 3 involves ion-exchanging the ammonium salt solution with the composite filter cake obtained in step 2, followed by calcination to obtain an ammonium-exchanged Y-type molecular sieve.

[0076] In one embodiment, the ammonium salt solution is added from the top of the composite filter cake and flows through the composite filter cake to perform ion exchange. The weight ratio of the ammonium salt solution in step 3 to the dry basis of the NaY molecular sieve in step 2 (i.e., the remaining NaY molecular sieve to be ion exchanged in step 2) is 0.05-0.25:1, based on ammonium salt.

[0077] In one embodiment, the ammonium salt in the ammonium salt solution in step 3 is a soluble ammonium salt, that is, an ammonium salt that is soluble in water. In another embodiment, the ammonium salt of the present invention is one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate, and ammonium bicarbonate, preferably ammonium chloride and ammonium sulfate.

[0078] In step 3 of this invention, during the ion exchange process, the ammonium salt solution is added from the top of the composite filter cake and flows through it. Ammonium ions that have not been exchanged by the NH-NaY molecular sieve filter cake layer can be further adsorbed by the humic substances and NaY molecular sieve in the NaY filter cake layer when passing through it. This can improve the utilization rate of ammonium salt and reduce the content of ammonium salt in the filtrate.

[0079] The ion-exchange molecular sieve can be treated by washing, drying, and calcining to obtain ammonium-exchange Y-type molecular sieves. Washing conditions are well known to those skilled in the art and are not particularly limited in this invention. For example, the washing temperature is 20-100℃, preferably 60-80℃, and the water volume is a water-to-molecular-sieve mass ratio of 1-15, preferably 3-5. Drying and calcining conditions are well known to those skilled in the art and are not particularly limited in this invention. For example, the drying temperature is room temperature to 200℃, preferably 100-150℃, the calcination temperature is 500-800℃, preferably 600-700℃, and the calcination time is 1-3 hours, preferably 2-3 hours.

[0080] In one embodiment, the ammonium-exchange Y-type molecular sieve obtained in step 3 is a cross-linked and calcined molecular sieve. In order to improve the ammonium exchange rate of the molecular sieve, the cross-linked and calcined molecular sieve can continue to undergo an ammonium ion exchange process. For example, it also includes step 4, which involves slurrying the cross-linked and calcined molecular sieve with water to form a filter cake, and then performing a secondary ion exchange with the filter cake by the ammonium salt solution and a secondary calcination to obtain the ammonium-exchange Y-type molecular sieve.

[0081] In one embodiment, the ammonium salt in the ammonium salt solution of step 4 of the present invention is a soluble ammonium salt, that is, an ammonium salt soluble in water. In another embodiment, the ammonium salt of the present invention is one or more of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate, and ammonium bicarbonate, preferably ammonium chloride and ammonium sulfate. The weight ratio of the ammonium salt solution in step 4 to the molecular sieve in step 3, calculated as ammonium salt, is 0.02-0.25:1.

[0082] The present invention does not impose a particular limitation on the thickness of the filter cake formed in step 4, and those skilled in the art can adjust it as needed.

[0083] In one embodiment, the filtrate from step 2 forming the NH-NaY molecular sieve filter cake layer, the exchange liquid obtained from step 3 ion exchange, and the exchange liquid obtained from step 4 secondary ion exchange can all be recycled as the ammonium salt solution in step 2. Ammonium salt solutions collected from other processes can also be used as the ammonium salt solution in step 2. This can achieve full utilization of ammonium salts and achieve zero ammonia nitrogen wastewater discharge.

[0084] The present invention also provides an apparatus for ammonium ion exchange of Y-type molecular sieves. The apparatus includes a horizontal belt filter, which comprises a NaY filter cake forming zone, a composite filter cake forming zone, and an ion exchange zone. The NaY filter cake forming zone is used to form a NaY filter cake layer, the composite filter cake forming zone is used to form an NH-NaY filter cake layer on the NaY filter cake layer, and the ion exchange zone is used for ion exchange between the ammonium salt solution and the composite filter cake.

[0085] The Y-type molecular sieve ammonium ion exchange device of the present invention forms a composite filter cake of NaY molecular sieve filter cake layer and NH-NaY molecular sieve filter cake layer. It can recover excess ammonium ions in the upper filtrate by taking advantage of the adsorption properties of ammonium ions by the NaY filter cake layer, thereby realizing the effective utilization of ammonium salts.

[0086] In one embodiment, the steps for performing ammonium ion exchange using the apparatus of the present invention are as follows:

[0087] 1) Slurry NaY molecular sieve, humic acid and water, and continuously load the resulting NaY molecular sieve slurry onto a horizontal belt filter to form a NaY molecular sieve filter cake layer, wherein the dry weight ratio of humic acid to NaY molecular sieve is 0.001-0.05:1.

[0088] 2) The NaY molecular sieve is slurried with an ammonium salt solution to obtain an NH-NaY cross-linked molecular sieve slurry. The NH-NaY cross-linked molecular sieve slurry is continuously loaded onto the NaY molecular sieve filter cake layer of the horizontal belt filter described in step 1) to form an NH-NaY cross-linked molecular sieve composite filter cake layer. The composite filter cake layer passes sequentially through the ion exchange zone and water washing zone of the horizontal belt filter, and is then dried and calcined to form a calcined molecular sieve. When passing through the ion exchange zone, an ammonium salt solution is added to the upper part of the composite filter cake layer.

[0089] 3) The zeolite molecular sieve described in step 2) is mixed with water to form a slurry. The slurry is continuously loaded onto a horizontal belt filter and passed sequentially through the filter cake forming zone, the ion exchange zone, and the water washing zone. When passing through the ion exchange zone, an ammonium salt solution is added to the upper part of the filter cake layer.

[0090] In one embodiment, a liquid receiver is provided below the filter cloth of the horizontal belt filter of the present invention, which can be in a depressurized or vacuum state to facilitate the collection of the filtrate.

[0091] In one specific implementation, please refer to Figure 1 and Figure 2 The ammonium ion exchange method of the Y-type molecular sieve of the present invention is as follows:

[0092] I. Formation of NaY filter cake

[0093] A slurry formed from NaY molecular sieve, humic acid, and water at 10-100℃, preferably 50-90℃, is continuously loaded from a mixing tank 1 onto the filter cloth 3 of a horizontal vacuum belt filter via pipeline 2. The filter cloth moves continuously into the NaY filter cake forming zone 4. A liquid receiver 8 is located below the filter cloth 3. The liquid receiver 8 is evacuated, and under vacuum, the liquid in the slurry on the filter cloth 3 passes through the filter cloth 3 and enters the liquid receiver 8. Simultaneously, a filter cake forms on the NaY slurry on the filter cloth 3. The loading rate of the NaY slurry should ensure that the thickness of the formed NaY filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm. The vacuum level in the vacuum chamber 8 ensures that the filter cake surface is free of cracks. The vacuum level in the vacuum chamber 8 is generally 0.02-0.08 MPa, preferably 0.05-0.08 MPa.

[0094] II. Formation of the filter cake

[0095] A primary molecular sieve slurry at 50-100℃ is continuously loaded from the mixing tank 5 through pipeline 6 onto the NaY filter cake layer of a horizontal vacuum belt filter, and moves with the filter cloth into the primary molecular sieve filter cake forming zone 7. The primary molecular sieve slurry comprises NaY molecular sieves and an ammonium salt solution. The ammonium salt solution can be provided by the secondary molecular sieve process liquid receiver 22, which reduces water consumption, recovers ammonia nitrogen from the secondary process filtrate, reduces wastewater discharge, and improves ammonium salt utilization. Simultaneously, the primary molecular sieve slurry forms a filter cake on the NaY filter cake on the filter cloth 3. The loading speed of the primary molecular sieve slurry should ensure that the thickness of the formed primary molecular sieve filter cake is 0.5-1.5 cm, preferably 0.8-1.5 cm.

[0096] III. Monoammonium Chloride Exchange

[0097] As the filter cloth 3 moves, the filter cake formed in the NaY filter cake forming zone 4 and the cross-linked filter cake forming zone 7 enters the ion exchange zone 11, where an ammonium salt solution at a temperature of 20-100℃, preferably 30-90℃, is added through the container 9 and pipeline 10. Under vacuum, the ammonium salt solution undergoes ion exchange as it passes through the filter cake.

[0098] IV. Washing

[0099] The washing method is well known to those skilled in the art. The filter cake obtained in the ion exchange zone 11 enters the water washing zone 14, and deionized water is added from the container 12 through the pipeline 13. The weight ratio of deionized water to molecular sieve is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100℃, preferably 30-90℃. Under vacuum, the liquid permeates through the filter cake, washing away residual ions, especially anions, from the filter cake.

[0100] V. Formation of the two-stage filter cake

[0101] A 1-baked molecular sieve slurry at 10-100℃, preferably 50-90℃, is continuously loaded from the mixing tank 15 onto the filter cloth 17 of a horizontal vacuum belt filter via pipeline 16. The filter cloth moves continuously into the cake-forming zone 18. A liquid receiver 22 is located below the filter cloth 17. The liquid receiver 22 is evacuated, and under vacuum, the liquid in the slurry on the filter cloth 17 passes through the filter cloth 17 and enters the liquid receiver 22. Simultaneously, a filter cake forms on the 1-baked molecular sieve slurry on the filter cloth 17. The loading rate of the 1-baked molecular sieve slurry should ensure that the thickness of the formed filter cake is 0.5-2.0 cm, preferably 0.8-1.5 cm. The vacuum level in the vacuum chamber 22 ensures that the filter cake surface is free of cracks. The vacuum level in the vacuum chamber 22 is generally 0.02-0.08 MPa, preferably 0.03-0.08 MPa.

[0102] VI. Diammonium Chloride Exchange

[0103] As the filter cloth 17 moves, the filter cake formed in the two-stage filter cake forming zone 18 enters the ion exchange zone 21, where an ammonium salt solution at a temperature of 20-100°C, preferably 30-90°C, is added through the container 19 and pipeline 20. Under vacuum, the ammonium salt solution undergoes ion exchange as it passes through the filter cake.

[0104] 7. Two washes

[0105] The washing method is well known to those skilled in the art. The filter cake obtained in the ion exchange zone 21 enters the washing zone 25, and deionized water is added from the container 23 via pipeline 24. The weight ratio of deionized water to molecular sieve is generally 1-15, preferably 2-10, and the temperature of the deionized water is 20-100℃, preferably 30-90℃. Under vacuum, the liquid permeates through the filter cake, washing away residual ions. The liquid in the liquid receiver 22 is output through pipeline 26.

[0106] The technical solution of the present invention will be further described in detail below through specific embodiments.

[0107] Raw material source:

[0108] 1) NaY molecular sieve: Industrial product, produced by Lanzhou Petrochemical Company, with a crystallinity of 94%, a silicon-to-aluminum ratio (nSiO2 / nAl2O3) of 5, and a Na2O mass content of 14.3%;

[0109] 2) Fulvic acid, brown humic acid, black humic acid, ammonium chloride, ammonium sulfate, ammonium phosphate, ammonium oxalate, and ammonium bicarbonate: analytical grade, all of which are chemical reagents.

[0110] Evaluation and analysis methods:

[0111] 1) Sodium oxide content of molecular sieve: analyzed by X-ray fluorescence spectrometry.

[0112] 2) Ammonia nitrogen content in the filtrate: determined by Nessler's reagent spectrophotometry.

[0113] The following examples use a cloth funnel filtration device to illustrate the method provided by the present invention. Since the cloth funnel filtration device also involves stages such as cake formation, ion exchange, and washing, but these steps are performed separately, it is similar to the continuous process in a belt filter.

[0114] Comparative Example 1

[0115] A 1-baked molecular sieve sample was prepared using conventional processes.

[0116] NaY molecular sieves were mixed with deionized water to prepare a slurry with a solid content of 180 g / L. The resulting slurry was heated to 80°C with stirring and poured into a Buchner funnel. Simultaneously, the filter cake in the Buchner funnel was evacuated to 0.07 MPa. Under vacuum, a filter cake of about 1 cm thickness was formed on the filter cloth of the Buchner funnel. The waste liquid in the filtration flask was then drained.

[0117] Maintain the vacuum in the filter flask. When there is almost no liquid on the surface of the filter cake, immediately and slowly add a mixed aqueous solution at 90°C containing 150 g / L of ammonium chloride. The rate of adding the mixed aqueous solution should be such that there is always liquid on the surface of the filter cake, until the amount of mixed aqueous solution added makes the weight ratio of ammonium chloride to molecular sieve 0.25.

[0118] Maintain the vacuum in the filter flask. When there is almost no liquid on the surface of the filter cake, immediately and slowly add deionized water at a temperature of 80°C. The rate at which the deionized water is added should be such that there is always liquid on the surface of the filter cake. Continue adding deionized water at a rate equivalent to 5 times the weight of the molecular sieve in the filter cake.

[0119] Continue evacuating until no more liquid flows out of the funnel, obtaining the dried filter cake and filtrate A.

[0120] The filter cloth was removed from the funnel, and the filter cake was removed from the filter cloth. The filter cake was dried at 120°C and calcined at 600°C for 2 hours to obtain a calcined molecular sieve. The sodium oxide content of the calcined molecular sieve was measured to be 4.3%, and the ammonia nitrogen content (as N, the same below) of the filtrate A was 2782 ppm.

[0121] Then, the sample was prepared according to the method provided in patent CN01134275.7.

[0122] The prepared molecular sieve, deionized water, and filtrate A were mixed and slurried to produce a molecular sieve slurry with a molecular sieve content of 110 g / L. The amount of salt (i.e., ammonium chloride and sodium chloride contained in the filtrate) was 1.1% by weight of the molecular sieve. The obtained molecular sieve slurry was heated to 60°C and poured into a Buchner funnel. Simultaneously, the filter flask was evacuated to 0.06 MPa, forming a filter cake with a thickness of 10 mm on the filter cloth. When there was no liquid on the surface of the filter cake, an ammonium chloride solution with a concentration of 150 g / L and a temperature of 90°C was immediately added. The addition speed was such that the surface of the filter cake did not crack, until all the solution was added. The amount of ammonium chloride solution was such that the weight ratio of ammonium chloride to molecular sieve was 0.25. 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. The weight ratio of deionized water to molecular sieve was 5. Then the filter cake was removed and filtrate B was collected. The filter cake was dried at 120°C to obtain Y-type molecular sieve D1. The sodium oxide content of the D1 molecular sieve sample was 1.1%, and the ammonia nitrogen content of the filtrate B was 3311 ppm.

[0123] Example 1

[0124] 1) Mix NaY molecular sieve, humic acid and water to make a molecular sieve slurry with a molecular sieve content of 180 g / L, wherein the mass ratio of humic acid to NaY molecular sieve is 0.05. Heat the obtained molecular sieve slurry to 80°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.07 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0125] 2) Mix NaY molecular sieve with ammonium-containing filtrate (filtrate B from Comparative Example 1) and slurry. The mass of the ammonium-containing filtrate is 5 times that of the NaY molecular sieve to prepare a molecular sieve slurry. Heat the obtained molecular sieve slurry to 70°C and stir for 1 hour. Pour it into the Buchner funnel onto the NaY filter cake from step 1). At the same time, evacuate the filter flask to 0.07 MPa to form a 10 mm thick filter cake on the filter cloth NaY filter cake.

[0126] 3) When there is no liquid on the surface of the filter cake, immediately add an ammonium chloride solution with an ammonium salt content of 150 g / L and a temperature of 90°C. The addition speed should ensure that the filter cake surface does not crack. The amount of ammonium chloride solution used should be such that the weight ratio of ammonium chloride to NaY molecular sieve in step 2) is 0.25. When there is no liquid on the surface of the filter cake, immediately add deionized water at a temperature of 80°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 5. Then remove the filter cake and collect the filtrate C. Dry the filter cake at 120°C and calcine it at 600°C for 2 hours to obtain a pre-calcined molecular sieve.

[0127] 4) Mix a batch of molecular sieve with water to make a molecular sieve slurry with a molecular sieve content of 110 g / L. Heat the obtained molecular sieve slurry to 60°C and pour it into a Buchner funnel. At the same time, evacuate the filter flask to 0.06 MPa to form a filter cake with a thickness of 10 mm on the filter cloth.

[0128] 5) When there is no liquid on the surface of the filter cake in step 4), immediately add an ammonium oxalate solution with an ammonium salt content of 150 g / L and a temperature of 90°C. The addition speed should ensure that the filter cake surface does not crack. The amount of ammonium oxalate used should be such that the weight ratio of ammonium oxalate to molecular sieve is 0.15. When there is no liquid on the surface of the filter cake, immediately add deionized water at a temperature of 90°C to wash the filter cake. The weight ratio of deionized water to molecular sieve is 5. Then remove the filter cake and collect filtrate D (ammonia nitrogen content of 1403 ppm) to obtain molecular sieve sample S1, with a sodium oxide mass content of 0.9% and filtrate C with an ammonia nitrogen content of 2 ppm.

[0129] Example 2

[0130] The operation steps are the same as in Example 1, wherein in step 1), the NaY molecular sieve slurry content is 300 g / L, the mass ratio of humic acid to NaY molecular sieve is 0.03, the slurry temperature is 15℃, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 5 mm.

[0131] Step 2) Mix NaY molecular sieve with ammonium-containing filtrate (filtrate D) and slurry. The mass of filtrate D is twice that of NaY molecular sieve. The slurry temperature is 50℃, and the mixture is stirred for 2 hours. The vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 15 mm.

[0132] Step 3) The ammonium sulfate content in the ammonium salt solution is 80 g / L, the temperature is 100℃, and the weight ratio of ammonium sulfate to NaY molecular sieve in Step 2) is 0.15. The deionized water temperature is 100℃, and the weight ratio of deionized water to molecular sieve is 3. Then, the filter cake is removed and the filtrate E is collected. The filter cake is dried at 200℃, calcined at 500℃ for 3 hours.

[0133] Step 4) The molecular sieve content of the slurry is 300 g / L, the slurry temperature is 80℃, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 5 mm.

[0134] Step 5) The ammonium oxalate content in the ammonium salt solution is 300 g / L, the temperature is 100℃, and the weight ratio of ammonium oxalate to molecular sieve is 0.25. The deionized water temperature is 40℃, and the weight ratio of deionized water to molecular sieve is 10. Then, the filter cake is removed and the filtrate F (ammonia nitrogen content is 2953 ppm) is collected to obtain molecular sieve sample S2, with a sodium oxide mass content of 1.1% and an ammonia nitrogen content of 3 ppm in filtrate E.

[0135] Example 3

[0136] The operation steps are the same as in Example 1, wherein in step 1), the NaY molecular sieve slurry content is 100 g / L, the mass ratio of humic acid to NaY molecular sieve is 0.001, the slurry temperature is 100℃, the vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 15 mm.

[0137] Step 2) Mix NaY molecular sieve with ammonium-containing filtrate (filtrate F) and slurry. The mass of filtrate F is 10 times that of NaY molecular sieve. The slurry temperature is 100℃, and the mixture is stirred for 0.5h. The vacuum degree of the filter bottle is 0.02 MPa, and the filter cake thickness is 5 mm.

[0138] Step 3) The ammonium sulfate solution has an ammonium sulfate content of 300 g / L, a temperature of 20℃, and a weight ratio of ammonium sulfate to NaY molecular sieve from Step 2) of 0.05. The deionized water temperature is 40℃, and the weight ratio of deionized water to molecular sieve is 10. Then, the filter cake is removed and the filtrate G is collected. The filter cake is dried at 20℃, calcined at 800℃ for 1 hour.

[0139] Step 4) The molecular sieve content of the slurry is 100 g / L, the slurry temperature is 40℃, the vacuum degree of the filter bottle is 0.08 MPa, and the filter cake thickness is 20 mm.

[0140] Step 5) The ammonium salt solution has an ammonium salt content of 80 g / L and a temperature of 100°C. The weight ratio of ammonium bicarbonate and ammonium chloride to the molecular sieve is 0.2, and the mass ratio of ammonium bicarbonate to ammonium chloride is 3:7. The deionized water temperature is 100°C, and the weight ratio of deionized water to the molecular sieve is 3. Then, the filter cake is removed and the filtrate H (ammonia nitrogen content is 3370 ppm) is collected to obtain molecular sieve sample S3, which has a sodium oxide mass content of 1.0%. The ammonia nitrogen content in the filtrate G is undetectable.

[0141] Example 4

[0142] The operation steps are the same as in Example 1, wherein in step 1), the NaY molecular sieve slurry content is 220 g / L, the mass ratio of humic acid to NaY molecular sieve is 0.02, the slurry temperature is 55℃, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 8 mm.

[0143] Step 2) Mix NaY molecular sieve with ammonium-containing filtrate (filtrate H) and slurry. The amount of filtrate H is 7 times that of NaY molecular sieve. Add ammonium chloride. The weight ratio of ammonium chloride to molecular sieve is 0.04. The slurry temperature is 80℃. Stir for 1.5h. The vacuum degree of the filter bottle is 0.04 MPa. The filter cake thickness is 13 mm.

[0144] Step 3) The ammonium phosphate solution has an ammonium phosphate content of 200 g / L, a temperature of 70℃, and a weight ratio of ammonium phosphate to NaY molecular sieve from Step 2) of 0.23. The deionized water temperature is 60℃, and the weight ratio of deionized water to molecular sieve is 8. Then, the filter cake is removed and filtrate I is collected. The filter cake is dried at 60℃, calcined at 700℃ for 1.5 h.

[0145] Step 4) The molecular sieve content of the slurry is 210 g / L, the slurry temperature is 70℃, the vacuum degree of the filter bottle is 0.04 MPa, and the filter cake thickness is 18 mm.

[0146] Step 5) The ammonium chloride solution has an ammonium chloride content of 220 g / L and a temperature of 60°C. The weight ratio of ammonium chloride to molecular sieve is 0.02. The deionized water temperature is 60°C, and the weight ratio of deionized water to molecular sieve is 7. The filter cake is dried at 200°C and then calcined at 500°C for 1 hour. The filter cake and filtrate J (ammonia nitrogen content of 221 ppm) are then removed to obtain molecular sieve sample S4, which has a sodium oxide mass content of 1.2% and an ammonia nitrogen content of 4 ppm in filtrate I.

[0147] As can be seen from the results of Examples S1 to S4, the ion exchange of Y-type molecular sieves using the method of the present invention results in a lower ammonia nitrogen content in the filtrate compared to conventional Y-type molecular sieve ion exchange methods, below 5 ppm, meeting the requirements for direct wastewater discharge. The molecular sieve prepared using the method of the present invention has a sodium oxide content comparable to that of the molecular sieve obtained in the comparative example. However, during the molecular sieve exchange process, the ammonia nitrogen content in the filtrate obtained by the method of the present invention is below 15 mg / kg, meeting the national standard "Integrated Wastewater Discharge Standard". In contrast, during the exchange process in the comparative example, a large amount of ammonium salt was not exchanged onto the molecular sieve and was lost with the filtrate during filtration, resulting in low ammonium salt utilization. The ammonia nitrogen content in the first and second cross-linked filtrates A and B exceeded 2000 ppm. If the ammonium entering the filtrate is not treated, it will cause environmental pollution.

[0148] As can be seen from Example S1 and Comparative Example D1, under the same ammonium salt dosage, the Y molecular sieve prepared by the method provided by this invention can balance ammonium salt utilization and sodium oxide content of the molecular sieve, and the filtrate has low ammonia nitrogen content, eliminating the need for ammonia nitrogen treatment and not affecting the subsequent use of the molecular sieve, thus showing good prospects for industrial application. Analysis data of the molecular sieve and filtrate from Example S1 and Comparative Example D1 show that the present invention forms a NaY molecular sieve layer and an NH-NaY molecular sieve layer composite filter cake, which is beneficial for improving ammonium salt utilization, reducing ammonia nitrogen wastewater discharge, and even achieving zero ammonia nitrogen wastewater discharge.

[0149] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for ammonium ion exchange of Y-type molecular sieves, characterized by, Includes the following steps: Step 1: Form a NaY molecular sieve filter cake layer from the NaY molecular sieve slurry; Step 2: Mix NaY molecular sieve with ammonium salt solution and slurry to form NH-NaY molecular sieve filter cake layer on the NaY molecular sieve filter cake layer, and obtain composite filter cake; Step 3: The ammonium salt solution is subjected to ion exchange with the composite filter cake obtained in Step 2, followed by calcination to obtain an ammonium-exchanged Y-type molecular sieve. In step 1, humic acid was also added to the slurry of NaY molecular sieve.

2. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, The humic acid is selected from fulvic acid, brown humic acid, black humic acid or a mixture thereof, and the dry weight ratio of the humic acid to the NaY molecular sieve in step 1 is 0.001-0.05:

1.

3. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, In step 2, the mass ratio of the ammonium salt solution to the dry NaY molecular sieve is 2-10:

1. The pulping temperature in step 2 is 50-100℃, and the pulping time is 0.5-2 hours.

4. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, The ammonium salt solution in step 3 is added from the top of the composite filter cake and flows through the composite filter cake to carry out ion exchange; the weight ratio of the ammonium salt solution in step 3 to the dry basis of NaY molecular sieve in step 2 is 0.05-0.25:1, calculated as ammonium salt.

5. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, The process also includes step 4, in which the Y-type molecular sieve calcined in step 3 is slurried with water to form a filter cake, and the filter cake is subjected to a second ion exchange with an ammonium salt solution and then calcined again to obtain an ammonium-exchanged Y-type molecular sieve.

6. The ammonium ion exchange method for Y-type molecular sieves according to claim 5, characterized in that, The ammonium salt solution, calculated as ammonium salt, has a weight ratio of 0.02-0.25:1 between the ammonium salt solution in step 4 and the Y-type molecular sieve after calcination in step 3.

7. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, The ammonium salts in the ammonium salt solutions in Step 2 and Step 3 are each one of ammonium chloride, ammonium sulfate, ammonium oxalate, ammonium phosphate, and ammonium bicarbonate.

8. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, The filtrate from step 2, which forms the NH-NaY molecular sieve filter cake layer, and the exchange solution obtained from step 3 (ion exchange) are recycled as the ammonium salt solution from step 2.

9. The ammonium ion exchange method for Y-type molecular sieves according to claim 1, characterized in that, In the NaY molecular sieve slurry of step 1, the content of NaY molecular sieve is 100-300 g / L.

10. An apparatus for ammonium ion exchange using Y-type molecular sieves, characterized in that, The ammonium ion exchange method for the Y-type molecular sieve according to any one of claims 1-9, the apparatus for ammonium ion exchange of the Y-type molecular sieve includes a horizontal belt filter, the horizontal belt filter includes a NaY filter cake forming zone, a composite filter cake forming zone and an ion exchange zone, wherein the NaY filter cake forming zone is used to form a NaY filter cake layer, the composite filter cake forming zone is used to form an NH-NaY filter cake layer on the NaY filter cake layer, and the ion exchange zone is used for ion exchange between the ammonium salt solution and the composite filter cake.

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