CN114433182B

CN114433182B - Molecular sieve containing rare earth element and preparation method thereof

Info

Publication number: CN114433182B
Application number: CN202011205648.4A
Authority: CN
Inventors: 杨柳; 李腾飞; 任靖; 殷喜平; 周岩; 武永安; 李柯志; 赵保槐; 胡海强; 韩帅; 苏海霞; 张南
Original assignee: China Petroleum and Chemical Corp; Sinopec Catalyst Co
Current assignee: China Petroleum and Chemical Corp; Sinopec Catalyst Co
Priority date: 2020-11-02
Filing date: 2020-11-02
Publication date: 2023-11-24
Anticipated expiration: 2040-11-02
Also published as: CN114433182A

Abstract

The invention relates to the field of preparation of molecular sieve catalytic materials, and discloses a molecular sieve containing rare earth elements and a preparation method thereof. The method comprises the following steps: 1) Under the microwave condition, carrying out a first ion exchange reaction on the sodium molecular sieve and a solution containing rare earth element ions to obtain a molecular sieve subjected to rare earth element ion exchange; 2) Roasting the molecular sieve subjected to the ion exchange of the rare earth elements obtained in the step 1) to obtain a roasted molecular sieve; 3) And 2) carrying out a second ion exchange reaction on the molecular sieve roasted in the step 2) and the solution containing ammonium ions to obtain the molecular sieve containing rare earth elements. The preparation method of the rare earth element-containing molecular sieve provided by the invention has the advantages of simple process flow, low sodium oxide content in the prepared rare earth element-containing molecular sieve and good hydrothermal stability.

Description

Molecular sieve containing rare earth element and preparation method thereof

Technical Field

The invention relates to the field of preparation of molecular sieve catalytic materials, in particular to a molecular sieve containing rare earth elements and a preparation method thereof.

Background

In the industry, a hydrothermal synthesis method is generally adopted to prepare a sodium molecular sieve, and the cations of the molecular sieve prepared by the hydrothermal method are sodium ions in general, but in practical application, the sodium ions are required to be exchanged for other cations, such as hydrogen ions, potassium ions, rare earth metal ions and the like, according to specific conditions.

Wherein REY, REHY and REUSY molecular sieves obtained by modifying the Y-type molecular sieves through ion exchange with rare earth are high-activity components of the catalytic cracking catalyst. REY molecular sieves (rare earth Y molecular sieves) were first developed and are also one of the most important major active components of high activity, high stability and vanadium toxicity resistant catalytic cracking catalysts.

Most of sodium in the catalytic cracking catalyst is carried in by the molecular sieve, and the least part is carried in by the salt in the raw oil. The excessive presence of sodium ions affects the thermal stability and selectivity of the catalyst, the poisoning effect is mainly represented by that the sodium ions can neutralize the acid active center of the catalyst, can react with hydrogen and rare earth on the molecular sieve to lead to the permanent deactivation of the active center of the catalyst, and can also form a melt with metal oxide at high temperature to damage the crystal lattice of the molecular sieve, thereby damaging the molecular sieve structure, reducing the specific surface area and leading to the reduction of micro-reactivity, and the poisoning effect can become more serious with the increase of temperature. Therefore, for preparing a catalytic cracking catalyst with excellent performance, the sodium content in the molecular sieve after ion exchange modification must be strictly controlled.

In order to improve the exchange degree of sodium ions and rare earth ions in the NaY-type molecular sieve and reduce the residual sodium content in the molecular sieve after ion exchange modification, the industrial preparation of the rare earth Y-type molecular sieve is generally realized by adopting a mode of alternately carrying out multiple times of exchange and high-temperature roasting. However, in the existing conventional preparation process of 'two-for-one baking' or 'two-for-two baking', the rare earth ion exchange time is long, the production and preparation flow is complicated, the production energy consumption is high, the preparation cost is high, and the sodium oxide content of the synthesized rare earth Y molecular sieve finished product is generally about 1.5%, so that the sodium oxide content in the finished product of the catalytic cracking catalyst can be reduced to below 0.2-0.3% index only by washing in the subsequent catalytic cracking catalyst preparation process.

In order to further optimize the preparation method of the rare earth Y molecular sieve, researchers have proposed a plurality of related modification methods. In order to make the rare earth element ion reach the exchange degree required by industry through one-time exchange, the scholars have studied to adopt the hot-press exchange method, but the long-time high-temperature and high-pressure exchange condition not only increases the production energy consumption, but also possibly influences the crystal structure of the molecular sieve.

CN1053808A reports a preparation method of rare earth Y molecular sieve, after exchanging NaY with rare earth salt solution once, roasting for 1-3 hours in 100% water vapor environment at 450-600 ℃. The method shortens the preparation flow, reduces the consumption and production cost of rare earth elements, and the prepared molecular sieve has relatively high hydrothermal structural stability and cracking activity stability.

CN101088613a discloses a preparation method of REY molecular sieve, after contacting NaY molecular sieve with rare earth ion-containing aqueous solution or with rare earth ion-containing aqueous solution and aluminum ion-containing solution or colloid, adding precipitant to precipitate part of rare earth ions on molecular sieve, roasting, and finally contacting with ammonium salt solution. The method is simple and easy to implement, the preparation flow of the REY molecular sieve can be shortened, and the prepared molecular sieve is suitable for processing heavy oil with high vanadium content and has good cracking reaction activity.

CN108097288A provides a method for preparing rare earth Y molecular sieve. Firstly mixing NaY molecular sieve, rare earth chloride solution and deionized water, then carrying out ion exchange, adding oxalic acid solution into the exchange liquid to completely precipitate the non-exchanged rare earth, adding rare earth chloride and deionized water into the filtered filter cake to carry out ion exchange, and filtering to obtain filter cake and reuse filtrate. The REY molecular sieve product is obtained after the filter cake is roasted by a muffle furnace, the recycled filtrate completely or partially replaces the rare earth chloride solution, and enters the ion exchange process of the NaY molecular sieve of the next batch, the utilization rate of rare earth almost reaches 100%, the production cost is reduced, and REY with high rare earth content can be obtained simultaneously, so that the REY molecular sieve has the advantages of high activity and high thermal stability.

CN1493402a discloses a method for mixing and exchanging ammonium and rare earth ions of a molecular sieve. And sequentially passing the molecular sieve filter cake through an ion exchange area on a horizontal belt filter to finish exchange, washing and filtering, and roasting. The method can realize the exchange of ammonium salt and rare earth compound simultaneously for the one-to-one baking Y-type molecular sieve, and has the advantages of low water consumption and high efficiency.

CN103058217a discloses a preparation method of a rare earth-containing Y molecular sieve. Taking NaY molecular sieve as raw material, performing ammonium exchange treatment, performing hydrothermal treatment at 550-750deg.C, and subjecting the water vapor treated Y molecular sieve to H-containing treatment ⁺ 、NH ₄ ⁺ 、RE ³⁺ And (3) treating the mixed solution of the organic solvent, and drying to obtain a finished product. The rare earth Y molecular sieve prepared by the method has uniform rare earth distribution on the molecular sieve and strong vanadium resistance.

CN103130240A discloses a modified Y-type molecular sieve and a preparation method thereof, which adopts a process of combining two-step baking with rare earth deposition, wherein the pH value of slurry in the process of rare earth deposition is regulated within 6-10 in the preparation process, and the obtained fractionThe rare earth content of the molecular sieve is 10-25 wt% calculated by rare earth oxide, the unit cell constant is 2.440-2.472nm, the crystallinity is 35-65%, the skeleton silicon-aluminum atomic ratio is 2.5-5.0, the intensity I of 2 theta = 11.8 +/-0.1 degree peak in the X-ray diffraction spectrum of the molecular sieve ₁ Intensity I of peak at 2θ=12.3±0.1° ₂ Ratio (I) ₁ /I ₂ ) The product value of the rare earth weight percent calculated by the rare earth oxide in the molecular sieve is more than 50. However, the ammonia nitrogen content in the wastewater produced by the method is high, and the environmental protection pressure is high.

In the prior art, the rare earth Y-type molecular sieve is prepared by adopting the one-cross one-baking, two-cross one-baking or two-cross two-baking process, and the preparation process is optimized to a certain extent in various aspects, so that the production flow is simplified, the rare earth utilization rate is improved, the stability of rare earth ions in a cage is improved, and the like. However, in general, the content of sodium oxide in the rare earth Y molecular sieve prepared by the method is still relatively high, and the washing operation is required in the subsequent preparation process of the catalyst cracking catalyst, so that the subsequent production is not facilitated, and the production cost is relatively high.

Disclosure of Invention

The invention aims to solve the problems of high sodium oxide content, long exchange period, long production process flow, high production energy consumption and the like in a rare earth element-containing molecular sieve in the prior art, and provides the rare earth element-containing molecular sieve and a preparation method thereof. The preparation method of the rare earth element-containing molecular sieve provided by the invention has the advantages of simple process flow, low sodium oxide content in the prepared rare earth element-containing molecular sieve and good hydrothermal stability.

In order to achieve the above object, an aspect of the present invention provides a method for preparing a rare earth element-containing molecular sieve, the method comprising:

1) Under the microwave condition, carrying out a first ion exchange reaction on the sodium molecular sieve and a solution containing rare earth element ions to obtain a molecular sieve subjected to rare earth element ion exchange;

2) Roasting the molecular sieve subjected to the ion exchange of the rare earth elements obtained in the step 1) to obtain a roasted molecular sieve;

3) And 2) carrying out a second ion exchange reaction on the molecular sieve roasted in the step 2) and the solution containing ammonium ions to obtain the molecular sieve containing rare earth elements.

Preferably, in step 1), the microwave conditions include: microwave power is 0.01-100KW, microwave heating time is 1-300min, heating to exchange temperature is 181-260 ℃, and keeping at the temperature for 1-720min; more preferably, the microwave conditions include: the microwave power is 0.1-10KW, the microwave heating time is 1-60min, the temperature is raised to 181-250 ℃, the temperature is kept for 1-120min, and further preferably, the microwave condition comprises: the microwave power is 0.1-1.5KW, the microwave heating time is 5-30min, the heating temperature is 181-220 ℃, and the temperature is kept for 5-120min.

Preferably, in step 1), the solution containing rare earth element ions is an aqueous solution, and the pH of the solution is 3-6 during the first ion exchange reaction.

Preferably, in the first ion exchange reaction, the weight ratio of water in the aqueous solution to the sodium molecular sieve is 5-30:1; more preferably, in the first ion exchange reaction, the weight ratio of water to sodium molecular sieve in the aqueous solution is 8-20:1.

Preferably, in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.02-1:1; more preferably, in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.2-0.8:1; further preferably, in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.4-0.8:1.

Preferably, in step 1), the sodium type molecular sieve is selected from one or more of an X type molecular sieve, a Y type molecular sieve, a ZSM-5 type molecular sieve, an a type molecular sieve and a beta molecular sieve; more preferably, the sodium type molecular sieve is selected from the group consisting of Y type molecular sieves.

Preferably, the rare earth element ion is derived from one or more of a hydrochloride salt of a rare earth element and a nitrate salt of a rare earth element.

Preferably, the rare earth element is selected from one or more of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium; more preferably, the rare earth element ions are from one or more of lanthanum chloride, cerium chloride, lanthanum nitrate, and cerium nitrate.

Preferably, the method further comprises: in the step 2), the molecular sieve obtained in the step 1) after ion exchange of the rare earth element is dried and then baked.

Preferably, the drying temperature is 80-150 ℃ and the drying time is 1-12h.

Preferably, the roasting temperature is 450-600 ℃, and the roasting time is 0.5-4h.

Preferably, in step 3), the solution containing ammonium ions is an aqueous solution, and the pH of the solution is 3-6 during the second ion exchange reaction.

Preferably, the molecular sieve obtained after roasting in the step 2) is used in an amount of 50-400g/L relative to 1L of the solution containing ammonium ions; more preferably, the molecular sieve obtained after calcination in step 2) is used in an amount of 100 to 350g/L relative to 1L of the solution containing ammonium ions.

Preferably, in the second ion exchange reaction, the weight ratio of the molecular sieve after roasting in the step 2) to the ammonium ion source compound in the aqueous solution is 1:0.01-6; more preferably, in the second ion exchange reaction, the weight ratio of the molecular sieve calcined in the step 2) to the ammonium ion source compound in the aqueous solution is 1:0.05-0.1.

Preferably, in step 3), the conditions of the second ion exchange reaction are: the exchange temperature is 5-90 ℃ and the exchange time is 1-30min; more preferably, the conditions of the second ion exchange reaction are: the exchange temperature is 15-80 ℃, and the exchange time is 10-20min.

Preferably, the ammonium ion is from one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium oxalate and ammonium carbonate; more preferably, the ammonium ion is derived from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

Preferably, the method further comprises: in step 3), after the second ion exchange reaction, the obtained molecular sieve containing rare earth elements is washed with a solution containing ammonium ions.

Preferably, after the second ion exchange reaction, when the obtained molecular sieve containing the rare earth element is washed by a solution containing ammonium ions, the weight ratio of the molecular sieve containing the rare earth element to the ammonium ion source compound is 1:0.01-1; more preferably, after the second ion exchange reaction, when the obtained rare earth element-containing molecular sieve is washed with an ammonium ion-containing solution, the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1:0.01-0.05.

Preferably, the method further comprises: in the step 3), the molecular sieve containing rare earth elements obtained after the second ion exchange is washed with water.

Preferably, in the water washing process, the weight ratio of the water to the molecular sieve obtained after the second ion exchange is 1-10:1; more preferably, the weight ratio of water to the molecular sieve obtained after the second ion exchange is 3-6:1 when the water is washed.

In a second aspect, the invention provides a molecular sieve containing rare earth elements, which is prepared by the method in the first aspect.

Preferably, the rare earth element-containing molecular sieve is a Y-type molecular sieve.

Preferably, the content of sodium oxide in the rare earth element-containing molecular sieve is 0.1 to 0.5 wt%.

Preferably, the rare earth element-containing molecular sieve has a rare earth content of 20 to 25 wt% in terms of rare earth oxide.

Through the technical scheme, sodium ions and rare earth element ions in the sodium molecular sieve can be subjected to ion exchange under the microwave condition, and then the rare earth element-containing molecular sieve with the residual sodium content of less than 0.5 weight percent (calculated as oxide) can be obtained after the exchange with ammonium ions.

At present, the content of sodium oxide in the rare earth Y molecular sieve prepared by two-step one-step baking in industrial production is generally about 1.5-1.6 wt%, while the content of residual sodium oxide in the rare earth element-containing molecular sieve prepared by the method provided by the invention is far lower than the current industrial production level, and the rare earth element-containing molecular sieve has the advantages of high ion exchange degree, short preparation period, capability of greatly reducing the production energy consumption cost and clean and environment-friendly effects.

In addition, the prepared rare earth element-containing molecular sieve has good hydrothermal stability, in particular, has higher micro-activity index after being subjected to hydrothermal treatment at 800 ℃ and 100% steam for 4h and 17h, has good cracking reaction activity, and can be used as an active component of a catalytic cracking catalyst.

Drawings

FIG. 1 is an X-ray diffraction pattern of a rare earth element-containing molecular sieve prepared in example 1 of the present invention.

Detailed Description

The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.

The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.

The first aspect of the present invention provides a method for producing a rare earth element-containing molecular sieve, wherein the method comprises:

The inventor of the present invention found that, firstly, sodium ions in the sodium molecular sieve are exchanged with rare earth element ions under the microwave condition, and then, the residual sodium ions in the molecular sieve are exchanged with ammonium ions after roasting, so that the residual sodium content in the molecular sieve can be significantly reduced, and the molecular sieve containing rare earth element with the residual sodium oxide content of less than 0.5 wt% can be obtained.

First, a first ion exchange reaction of exchanging sodium ions in a sodium molecular sieve with rare earth ions under microwave conditions will be described.

According to the invention, under the microwave condition, the sodium molecular sieve and the solution containing rare earth element ions are subjected to a first ion exchange reaction to obtain the molecular sieve after rare earth element ion exchange.

In the present invention, preferably, the solution containing rare earth element ions is an aqueous solution, and the pH of the solution is 3 to 6, preferably, the pH of the solution is 3 to 5, in the first ion exchange reaction.

In the invention, the content of the sodium type molecular sieve in the aqueous solution containing rare earth element ions can be changed in a larger range, and preferably, the weight ratio of water in the aqueous solution to the sodium type molecular sieve is 5-30:1 in the first ion exchange reaction; more preferably, in the first ion exchange reaction, the weight ratio of water to sodium molecular sieve in the aqueous solution is 8-20:1. Although increasing the amount of the sodium type molecular sieve may increase the treatment efficiency, when the amount of the sodium type molecular sieve exceeds the above range, the degree of ion exchange may be decreased, affecting the effect of the first ion exchange reaction.

In the invention, in the first ion exchange, the weight ratio of the rare earth element ion source compound to the sodium type molecular sieve in the aqueous solution containing rare earth element ions can also be changed within a large range, and preferably, in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium type molecular sieve in the aqueous solution is 0.02-1:1; more preferably, in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.2-0.8:1; further preferably, in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.4-0.8:1. When the weight ratio of the rare earth element ion source compound to the sodium type molecular sieve is within the range, the ion exchange degree can be improved, and the cost can be saved.

According to the present invention, the sodium type molecular sieve may be various sodium type molecular sieves commonly used in the art, and as such sodium type molecular sieves, for example, one or more selected from the group consisting of an X type molecular sieve, a Y type molecular sieve, a ZSM-5 type molecular sieve, an a type molecular sieve and a beta type molecular sieve; preferably, the sodium type molecular sieve is a Y type molecular sieve.

In the present invention, the rare earth element ion may be derived from one or more of a hydrochloride salt of a rare earth element and a nitrate salt of a rare earth element.

The rare earth element may be, for example, one or more selected from lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium.

In a particularly preferred embodiment of the present invention, the rare earth element ion is selected from one or more of lanthanum chloride, cerium chloride, lanthanum nitrate and cerium nitrate.

In the present invention, preferably, the rare earth element ion source compound is mixed with water to obtain a solution containing rare earth element ions, and then sodium molecular sieve is added to perform the first ion exchange reaction under the microwave condition.

According to the invention, the first ion exchange reaction is carried out under microwave conditions comprising: microwave power is 0.01-100KW, microwave heating time is 1-300min, heating to exchange temperature is 181-260 ℃, and keeping at the temperature for 1-720min; preferably, the microwave conditions include: microwave power is 0.1-10KW, microwave heating time is 1-60min, heating to exchange temperature is 181-250 ℃, and keeping at the temperature for 1-120min; more preferably, the microwave conditions include: the microwave power is 0.1-1.5KW, the microwave heating time is 5-30min, the heating temperature is 181-220 ℃, and the temperature is kept for 5-120min. By making the rare earth element ions and sodium ions in the molecular sieve perform first ion exchange under the above conditions, the ion exchange rate can be promoted, the ion exchange degree can be improved, and the content of sodium ions in the molecular sieve can be reduced.

According to the present invention, after the first ion exchange reaction is performed, the molecular sieve after the rare earth element ion exchange can be obtained by solid-liquid separation, which can be performed by a method conventionally performed in the art, for example, solid-liquid separation can be achieved by a method such as filtration, centrifugation, or the like. In the present invention, preferably, the molecular sieve after ion exchange of rare earth element is obtained by filtration.

In the present invention, in order to remove impurities contained in the rare earth element ion-exchanged molecular sieve obtained in step 1), the obtained rare earth element ion-exchanged molecular sieve may preferably be washed. Thus, preferably, the process of the present invention comprises a step of washing the rare earth element ion molecular sieve obtained in step 1).

The washing may be carried out using various methods conventional in the art for washing molecular sieves. For example, the washing may be performed with deionized water, and the weight ratio of deionized water to molecular sieve may be 2-10:1, preferably 3-6:1.

In addition, according to the present invention, the method may further include: before the step 2), drying the molecular sieve obtained after the ion exchange of the rare earth element in the step 1), wherein the drying temperature is preferably 80-150 ℃ and the drying time is 1-12h; more preferably, the drying temperature is 100-150 ℃ and the drying time is 2-6h.

According to the invention, in order to promote sodium ion migration and facilitate the subsequent second ion exchange, the molecular sieve obtained in the step 1) after the ion exchange of the rare earth element is roasted. The conditions of the calcination may be conventional conditions for calcination of molecular sieves in the art, preferably, the calcination temperature is 450 to 600 ℃ and the calcination time is 0.5 to 4 hours; more preferably, the roasting temperature is 450-550 ℃ and the roasting time is 1-3h.

Next, the molecular sieve calcined in step 2) and the solution containing ammonium ions are subjected to a second ion exchange reaction.

In the present invention, preferably, the solution containing ammonium ions is an aqueous solution, and the pH of the solution is 3 to 6, preferably, the pH of the solution is 3 to 5, in the second ion exchange reaction.

According to the invention, the amount of molecular sieve obtained after calcination in step 2) can be varied over a wide range in relation to the solution containing ammonium ions in the second ion exchange reaction. Preferably, the molecular sieve obtained after roasting in the step 2) is used in an amount of 50-400g/L relative to 1L of the solution containing ammonium ions; more preferably, the molecular sieve obtained after calcination in step 2) is used in an amount of 100 to 350g/L relative to 1L of the solution containing ammonium ions.

According to the present invention, the content of the ammonium ion source compound in the ammonium ion-containing solution in the second ion exchange reaction may be determined according to the weight of the molecular sieve, and preferably, in the second ion exchange reaction, the weight ratio of the molecular sieve calcined in the step 2) to the ammonium ion source compound in the ammonium ion-containing solution is 1:0.01-6; more preferably, in the second ion exchange reaction, the weight ratio of the molecular sieve after roasting in the step 2) to the ammonium ion source compound in the solution containing ammonium ions is 1:0.05-2; further preferably, in the second ion exchange reaction, the weight ratio of the molecular sieve calcined in the step 2) to the ammonium ion source compound in the solution containing ammonium ions is 1:0.05-0.1.

In the present invention, the ammonium ion may be derived from various ammonium salts conventionally used in the art, for example, may be derived from one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium oxalate and ammonium carbonate; preferably, the ammonium ion is derived from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

In the present invention, preferably, the ammonium ion source compound is mixed with water to obtain an aqueous solution containing ammonium ions, and then the aqueous solution is added to the molecular sieve calcined in step 2) to perform a second ion exchange reaction.

According to the invention, in step 3), the conditions of the second ion exchange reaction are: the exchange temperature is 5-90 ℃ and the exchange time is 1-30min; preferably, the conditions of the second ion exchange reaction are: the exchange temperature is 15-80 ℃, and the exchange time is 5-30min; more preferably, the conditions of the second ion exchange reaction are: the exchange temperature is 25-80 ℃, and the exchange time is 10-20min.

In the present invention, in order to further exchange the residual sodium ions in the molecular sieve, preferably, the method further comprises: in step 3), after the second ion exchange reaction, the obtained molecular sieve containing rare earth elements is washed with a solution containing ammonium ions.

When washing with an ammonium ion-containing solution, preferably, the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1:0.01-1; more preferably, the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1:0.01-0.5; further preferably, the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1:0.01-0.05.

According to the present invention, in order to further remove impurities in the obtained rare earth element-containing molecular sieve, preferably, the method further comprises: in the step 3), the molecular sieve containing rare earth elements obtained after the second ion exchange is washed; when water washing is carried out, preferably, the weight ratio of water to molecular sieve is 1-10:1; more preferably, the weight ratio of water to molecular sieve is 3-6:1.

In a second aspect, the present invention provides a rare earth element-containing molecular sieve prepared by the method of the first aspect of the present invention. Preferably, the rare earth element-containing molecular sieve is a Y-type molecular sieve.

In addition, in the rare earth element-containing molecular sieve, the content of sodium oxide is 0.1-0.5 wt%, and the content of rare earth is 20-25 wt% calculated by rare earth oxide.

The present invention will be described in detail with reference to examples, but the present invention is not limited to the examples.

In the following examples and comparative examples, naY molecular sieves were used as produced by chinese petrochemical catalyst company, longline division.

In the following examples and comparative examples, the method for measuring the contents of rare earth oxide and residual sodium oxide in the molecular sieve is as follows: and grinding the dried powder sample uniformly, tabletting and forming, and measuring the contents of rare earth oxide and residual sodium oxide in the sample on an X-ray fluorescence spectrometer.

In the following examples and comparative examples, the molecular sieve lattice collapse temperature was measured using a high temperature differential thermal analyzer.

Example 1

1) Mixing a NaY molecular sieve with an aqueous solution containing lanthanum chloride and cerium chloride, wherein the weight ratio of water to the NaY molecular sieve is 20:1, the weight ratio of the total amount of lanthanum chloride and cerium chloride to the NaY molecular sieve is 0.8:1, the pH was adjusted to 4.5 with a dilute hydrochloric acid solution (concentration 5% by weight). And then placing the obtained mixed solution under microwave conditions for first ion exchange, wherein the microwave conditions comprise: the frequency is 2450MHz, the microwave power is 1.5KW, the temperature is raised from 25 ℃ to 220 ℃ at the exchange temperature, the microwave heating time is 5min, and the microwave heating time is kept for 5min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with the volume of 6 times after the filtering, and drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

2) Roasting the rare earth element ion-exchanged molecular sieve obtained in the step 1) for 3 hours at 550 ℃ to obtain a roasted molecular sieve;

3) Mixing the baked molecular sieve obtained in the step 2) with an aqueous solution containing ammonium chloride, wherein the dosage of the molecular sieve obtained in the step 2) after baking is 200g/L relative to 1L of the aqueous solution of ammonium chloride, the weight ratio of the ammonium chloride to the baked molecular sieve obtained in the step 2) is 0.1:1, adjusting the pH value to 4.5 by using a dilute hydrochloric acid solution (the concentration is 5 weight percent), and then carrying out second ion exchange on the mixed solution, wherein the conditions of the second ion exchange comprise: pulping at 80deg.C for 20min, and filtering after exchange;

4) And (3) carrying out ammonium washing on the molecular sieve obtained after the second ion exchange in the step (3) by using an ammonium chloride aqueous solution, wherein the weight ratio of the molecular sieve to an ammonium ion source compound is 1:0.05 during the ammonium washing, and then washing the obtained molecular sieve by using deionized water with the volume of 5 times to obtain the molecular sieve S-1 containing rare earth elements, wherein the physicochemical properties are shown in a table 1, and the X-ray diffraction spectrum is shown in a graph 1. As can be seen from fig. 1, the rare earth ion exchange under the microwave condition does not destroy the crystal structure of the molecular sieve, and characteristic diffraction peaks of the rare earth ions in sodalite cages and supercages appear.

Example 2

1) Mixing a NaY molecular sieve with an aqueous solution containing lanthanum chloride and cerium nitrate, wherein the weight ratio of water to the NaY molecular sieve is 15:1, the weight ratio of the total amount of lanthanum chloride and cerium nitrate to the NaY molecular sieve is 0.5:1, the pH was adjusted to 4.5 with a dilute hydrochloric acid solution (concentration 5% by weight). And then placing the obtained mixed solution under microwave conditions for first ion exchange, wherein the microwave conditions comprise: the frequency is 2450MHz, the microwave power is 0.5KW, the temperature is raised from 25 ℃ to 181 ℃ at the exchange temperature, the microwave heating time is 5min, and the temperature is kept at the exchange temperature for 25min. Filtering after the exchange is finished, washing the obtained product by using deionized water with the volume of 6 times after the filtering, and drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

2) Roasting the molecular sieve subjected to the ion exchange of the rare earth element obtained in the step 1) at 550 ℃ for 2.5 hours to obtain a roasted molecular sieve;

3) Mixing the baked molecular sieve obtained in the step 2) with an aqueous solution containing ammonium chloride, wherein the dosage of the molecular sieve obtained in the step 2) after baking is 200g/L relative to 1L of the aqueous solution of ammonium chloride, the weight ratio of the ammonium chloride to the baked molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH value to 4.5 by using a dilute hydrochloric acid solution (the concentration is 5 weight percent), and then carrying out second ion exchange on the mixed solution, wherein the conditions of the second ion exchange comprise: pulping at 25deg.C for 20min, and filtering after exchange;

4) And (2) performing ammonium washing on the second ion-exchanged molecular sieve obtained in the step (3) by using an ammonium chloride aqueous solution, wherein the weight ratio of the molecular sieve to an ammonium ion source compound is 1:0.01 during ammonium washing, and then washing the obtained molecular sieve by using deionized water with the volume of 5 times to obtain the molecular sieve S-2 containing rare earth elements, and the physicochemical properties of the molecular sieve S-2 are shown in a table 1.

Example 3

1) Mixing a NaY molecular sieve with an aqueous solution containing lanthanum nitrate and cerium chloride, wherein the weight ratio of water to the NaY molecular sieve is 10:1, the weight ratio of the total amount of lanthanum nitrate and cerium chloride to the NaY molecular sieve is 0.5:1, the pH was adjusted to 4 with a dilute hydrochloric acid solution (concentration 5% by weight). And then placing the obtained mixed solution under microwave conditions for first ion exchange, wherein the microwave conditions comprise: the frequency is 2450MHz, the microwave power is 1KW, the temperature is raised from 25 ℃ to 190 ℃ at the exchange temperature, the microwave heating time is 5min, and the microwave heating time is kept for 20min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with the volume of 6 times after the filtering, and drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

2) Roasting the rare earth element ion-exchanged molecular sieve obtained in the step 1) for 2 hours at 550 ℃ to obtain a roasted molecular sieve;

3) Mixing the baked molecular sieve obtained in the step 2) with an aqueous solution containing ammonium chloride, wherein the dosage of the molecular sieve obtained in the step 2) after baking is 200g/L relative to 1L of the aqueous solution of ammonium chloride, the weight ratio of the ammonium chloride to the baked molecular sieve obtained in the step 2) is 0.1:1, adjusting the pH value to 4.5 by using a dilute hydrochloric acid solution (the concentration is 5 weight percent), and then carrying out second ion exchange on the mixed solution, wherein the conditions of the second ion exchange comprise: pulping at 60deg.C for 10min, and filtering after exchange;

4) Washing the molecular sieve obtained in the step 3) after the second ion exchange with deionized water with the volume of 5 times to obtain the molecular sieve S-3 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve are shown in a table 1.

Example 4

1) Mixing a NaY molecular sieve with an aqueous solution containing lanthanum chloride, wherein the weight ratio of water to the NaY molecular sieve is 15:1, the weight ratio of lanthanum chloride to NaY molecular sieve is 0.55:1, the pH was adjusted to 4.5 with a dilute hydrochloric acid solution (concentration 10% by weight). And then placing the obtained mixed solution under microwave conditions for first ion exchange, wherein the microwave conditions comprise: the frequency is 2450MHz, the microwave power is 0.3KW, the temperature is raised from 25 ℃ to 190 ℃ at the exchange temperature, the microwave heating time is 5min, and the temperature is kept at the exchange temperature for 15min. Filtering after the exchange is finished, washing the obtained product by using deionized water with the volume of 6 times after the filtering, and drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

3) Mixing the baked molecular sieve obtained in the step 2) with an aqueous solution containing ammonium sulfate, wherein the dosage of the molecular sieve obtained in the step 2) after baking is 200g/L relative to 1L of the aqueous solution of ammonium sulfate, the weight ratio of the ammonium sulfate to the baked molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH value to 4.5 by using a dilute hydrochloric acid solution (the concentration is 10 weight percent), and then carrying out second ion exchange on the mixed solution, wherein the conditions of the second ion exchange comprise: pulping at 45deg.C for 10min, and filtering after exchange;

4) Washing the molecular sieve obtained in the step 3) after the second ion exchange with deionized water with the volume of 5 times to obtain the molecular sieve S-4 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve are shown in a table 1.

Example 5

1) Mixing a NaY molecular sieve with an aqueous solution containing lanthanum chloride, wherein the weight ratio of water to the NaY molecular sieve is 15:1, the weight ratio of lanthanum chloride to NaY molecular sieve is 0.5:1, the pH was adjusted to 4.5 with a dilute hydrochloric acid solution (concentration 5% by weight). And then placing the obtained mixed solution under microwave conditions for first ion exchange, wherein the microwave conditions comprise: the frequency is 2450MHz, the microwave power is 0.2KW, the temperature is raised from 25 ℃ to 190 ℃ at the exchange temperature, the microwave heating time is 5min, and the temperature is kept for 10min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with the volume of 6 times after the filtering, and drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

3) Mixing the baked molecular sieve obtained in the step 2) with an aqueous solution containing ammonium sulfate, wherein the dosage of the molecular sieve obtained in the step 2) after baking is 200g/L relative to 1L of the aqueous solution of ammonium sulfate, the weight ratio of the ammonium sulfate to the baked molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH value to 4.5 by using a dilute hydrochloric acid solution (the concentration is 5 weight percent), and then carrying out second ion exchange on the mixed solution, wherein the conditions of the second ion exchange comprise: pulping at 30deg.C for 10min, and filtering after exchange;

4) Washing the molecular sieve obtained in the step 3) after the second ion exchange with deionized water with the volume of 5 times to obtain the molecular sieve S-5 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve S-5 are shown in a table 1.

Example 6

1) Mixing a NaY molecular sieve with an aqueous solution containing lanthanum chloride, wherein the weight ratio of water to the NaY molecular sieve is 10:1, the weight ratio of lanthanum chloride to NaY molecular sieve is 0.4:1, the pH was adjusted to 4.5 with a dilute hydrochloric acid solution (concentration 5% by weight). And then placing the obtained mixed solution under microwave conditions for first ion exchange, wherein the microwave conditions comprise: the frequency was 2450MHz, the microwave power was 0.1KW, the temperature was raised from 25℃to 185℃at a temperature exchange time of 5min, and the microwave temperature was maintained at this temperature exchange time for 8min. Filtering after the exchange is finished, washing the obtained product by using deionized water with the volume of 6 times after the filtering, and drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

3) Mixing the baked molecular sieve obtained in the step 2) with an aqueous solution containing ammonium sulfate, wherein the dosage of the molecular sieve obtained in the step 2) after baking is 200g/L relative to 1L of the aqueous solution of ammonium sulfate, the weight ratio of the ammonium sulfate to the baked molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH value to 4.5 by using a dilute hydrochloric acid solution (the concentration is 5 weight percent), and then carrying out second ion exchange on the mixed solution, wherein the conditions of the second ion exchange comprise: pulping at 15deg.C for 10min, and filtering after exchange;

4) Washing the molecular sieve obtained in the step 3) after the second ion exchange with deionized water with the volume of 5 times to obtain the molecular sieve S-6 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve are shown in a table 1.

Comparative example 1

The procedure of example 1 was followed, except that:

the conventional two-stage one-bake process is employed, i.e., in step 1), the conditions for the first ion exchange include: and heating the obtained mixed solution from 25 ℃ to exchange temperature to 220 ℃ by adopting an electric heating mode, wherein the heating time is 120min, and keeping the temperature at the exchange temperature for 5min. Molecular sieve D-1 containing rare earth element is obtained, and its physicochemical properties are shown in Table 1.

Comparative example 2

The procedure of example 1 was followed, except that:

the molecular sieve D-2 containing rare earth elements is obtained after roasting without carrying out the step 3) and the step 4), and the physicochemical properties are shown in the table 1.

TABLE 1

Product numbering	S-1	S-2	S-3	S-4	S-5	S-6	D-1	D-2
									Na ₂ O content (wt.%)	0.12	0.20	0.35	0.42	0.48	0.5	1.6	2.0
Re ₂ O ₃ Content (wt.%)	23.6	23.4	23.1	22.8	22.4	22.1	19.1	23.8
									Collapse temperature (. Degree. C.)	1036	1032	1031	1028	1025	1021	1011	1028

As can be seen from the data in Table 1, the rare earth element-containing molecular sieve prepared by the method provided by the invention has much lower content of residual sodium oxide than the conventional secondary-primary baked product (D-1) and higher thermal stability.

Test case

1) Sample pretreatment: repeatedly performing ion exchange and washing on the molecular sieve samples D-1 and D-2 containing the rare earth elements obtained in the comparative example by using an ammonium chloride aqueous solution until Na in the D-1 and D-2 molecular sieves ₂ The content of O is lower than 0.5 weight percent, wherein, during ion exchange, the weight ratio of the molecular sieve to the ammonium chloride to the water is molecular sieve to the ammonium chloride to the water=1 to 0.3 to 10, the exchange temperature is 60 ℃, and the exchange time is 30min each time; and then drying the obtained D-1 and D-2 molecular sieves at 120 ℃ for 6 hours to obtain the treated molecular sieves D-1 'and D-2' containing the rare earth elements.

2) Sample hydrothermal aging: and (3) carrying out 100% steam aging on the rare earth element-containing molecular sieve and the rare earth element-containing molecular sieves D-1 'and D-2' prepared in the examples 1-6 by adopting a rotary steaming aging device, wherein the aging temperature is 800 ℃, the aging time is 4h and 17h respectively, and the water inlet rate is 1.8g/min.

3) Micro-activity index test: 5 g of the rare earth element-containing molecular sieve prepared in examples 1 to 6 subjected to the hydrothermal aging treatment in step 2) and the rare earth element-containing molecular sieves D-1 'and D-2' were charged into a standard microreactor whose bed temperature was controlled at 460 ℃, 1.56 g of standard raw oil was injected into the reactor at a constant speed for reaction within 70 seconds, then purged with nitrogen for 10 minutes, the reaction product was collected in a bottle which was placed in a cold trap mixed with ice water, and the liquid phase reaction product was analyzed by gas chromatography, and the micro-activity index of each molecular sieve sample was calculated from the analysis data: micro-activity index (MA) = [ 1-liquid recovery oil mass× (percentage content of gasoline component in 1-liquid recovery oil)/standard oil mass ] ×100%.

The test results are shown in Table 2.

TABLE 2

Product numbering	S-1	S-2	S-3	S-4	S-5	S-6	D-1’	D-2’
									Micro-activity index (800-4 h)	84.2	82.4	81.8	80.9	79.9	78.6	77.8	78.2
Micro-activity index (800-17 h)	77.5	76.4	75.1	74.8	73.4	72.1	70.1	70.8

As can be seen from the data in Table 2, the rare earth element-containing molecular sieve prepared by the method provided by the invention has obviously better hydrothermal stability and retains stronger catalytic cracking activity after being subjected to severe hydrothermal treatment compared with the product prepared by the conventional two-step one-baking process.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims

1. A method for preparing a rare earth element-containing molecular sieve, comprising the steps of:

3) Carrying out a second ion exchange reaction on the molecular sieve roasted in the step 2) and the solution containing ammonium ions to obtain the molecular sieve containing rare earth elements,

the microwave conditions include: microwave power is 0.1-1.5KW, microwave heating time is 5-30min, heating to exchange temperature is 181-220 ℃, and maintaining at the temperature for 5-120min;

the conditions for the second ion exchange reaction are: the exchange temperature is 15-80 ℃, and the exchange time is 10-20min;

in the step 1), the solution containing rare earth element ions is an aqueous solution, and the pH value of the solution is 3-6 during the first ion exchange reaction;

in the first ion exchange reaction, the weight ratio of water in the aqueous solution to the sodium molecular sieve is 5-30:1;

in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.02-1:1;

the method further comprises the steps of: in the step 2), drying and roasting the molecular sieve subjected to the ion exchange of the rare earth element obtained in the step 1);

the drying temperature is 80-150 ℃ and the drying time is 1-12h;

the roasting temperature is 450-600 ℃, and the roasting time is 0.5-4h.

2. The process of claim 1, wherein the weight ratio of water to sodium molecular sieve in the aqueous solution at the time of the first ion exchange reaction is 8-20:1;

in the first ion exchange reaction, the weight ratio of the rare earth element ion source compound to the sodium molecular sieve in the aqueous solution is 0.2-0.8:1.

3. The method of claim 2, wherein the weight ratio of the rare earth ion source compound to the sodium molecular sieve in the aqueous solution is 0.4-0.8:1 in the first ion exchange reaction.

4. The process of claim 1 or 2, wherein in step 1), the sodium-type molecular sieve is selected from one or more of an X-type molecular sieve, a Y-type molecular sieve, a ZSM-5-type molecular sieve, an a-type molecular sieve, and a beta-type molecular sieve;

the rare earth element ions are derived from one or more of a hydrochloride salt of a rare earth element and a nitrate salt of a rare earth element.

5. The process of claim 4, wherein the sodium molecular sieve is selected from the group consisting of Y-type molecular sieves;

the rare earth element is selected from one or more of lanthanum, cerium, praseodymium, neodymium, promethium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, lutetium, yttrium, and scandium.

6. The method of claim 5, wherein the rare earth element ions are from one or more of lanthanum chloride, cerium chloride, lanthanum nitrate, and cerium nitrate.

7. The method according to claim 1 or 2, wherein in step 3), the solution containing ammonium ions is an aqueous solution, and the pH of the solution is 3 to 6 at the time of the second ion exchange reaction;

the dosage of the molecular sieve obtained after roasting in the step 2) is 50-400g/L relative to 1L of the solution containing ammonium ions;

in the second ion exchange reaction, the weight ratio of the molecular sieve after roasting in the step 2) to the ammonium ion source compound in the aqueous solution is 1:0.01-6.

8. The process according to claim 7, wherein the molecular sieve obtained after calcination in step 2) is used in an amount of 100 to 350g/L relative to 1L of the solution containing ammonium ions;

in the second ion exchange reaction, the weight ratio of the molecular sieve after roasting in the step 2) to the ammonium ion source compound in the aqueous solution is 1:0.05-0.1.

9. The method according to claim 1 or 2, wherein,

the ammonium ion is derived from one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium oxalate and ammonium carbonate.

10. The method of claim 9, wherein the ammonium ion is from one or more of ammonium chloride, ammonium sulfate, and ammonium nitrate.

11. The method according to claim 1 or 2, wherein the method further comprises: in step 3), after the second ion exchange reaction, the obtained molecular sieve containing rare earth elements is washed with a solution containing ammonium ions.

12. The method of claim 11, wherein the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1:0.01-1 when the obtained rare earth element-containing molecular sieve is washed with the ammonium ion-containing solution after the second ion exchange reaction.

13. The method of claim 12, wherein the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1:0.01-0.05 when the obtained rare earth element-containing molecular sieve is washed with the ammonium ion-containing solution after the second ion exchange reaction.

14. The method according to claim 1 or 2, wherein the method further comprises: in the step 3), the molecular sieve containing rare earth elements obtained after the second ion exchange is washed with water.

15. The method of claim 14, wherein the weight ratio of water to the molecular sieve obtained after the second ion exchange is 1-10:1 when the water is washed.

16. The method of claim 15, wherein the weight ratio of water to the molecular sieve obtained after the second ion exchange is 3-6:1 when the water is washed.

17. A rare earth element-containing molecular sieve produced by the production method of a rare earth element-containing molecular sieve according to any one of claims 1 to 16.

18. The rare earth element-containing molecular sieve according to claim 17, wherein the rare earth element-containing molecular sieve is a Y-type molecular sieve;

the content of sodium oxide in the rare earth element-containing molecular sieve is 0.1 to 0.5 weight percent;

in the rare earth element-containing molecular sieve, the content of rare earth is 20-25 wt% calculated by rare earth oxide.