CN114433182A

CN114433182A - Molecular sieve containing rare earth elements and preparation method thereof

Info

Publication number: CN114433182A
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: 2022-05-06
Anticipated expiration: 2040-11-02
Also published as: CN114433182B

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 a sodium type molecular sieve and a solution containing rare earth element ions to obtain a rare earth element ion exchanged molecular sieve; 2) roasting the molecular sieve subjected to the rare earth element ion exchange obtained in the step 1) to obtain a roasted molecular sieve; 3) and (3) carrying out a second ion exchange reaction on the molecular sieve roasted in the step 2) and a solution containing ammonium ions to obtain the molecular sieve containing the rare earth elements. The preparation method of the rare earth element-containing molecular sieve provided by the invention is simple in process flow, and the prepared rare earth element-containing molecular sieve is low in sodium oxide content and good in hydrothermal stability.

Description

Molecular sieve containing rare earth elements 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

The sodium type molecular sieve is generally prepared industrially by a hydrothermal synthesis method, and the cation of the molecular sieve prepared by the hydrothermal method is sodium ion in general, but in practical application, the sodium ion in the molecular sieve needs to be exchanged for other cations, such as hydrogen ion, potassium ion, rare earth metal ion and the like according to specific situations.

The REY, REHY and REUSY molecular sieves obtained by exchanging and modifying the Y-type molecular sieve with rare earth ions are high-activity components of the catalytic cracking catalyst. The development of REY molecular sieve (rare earth Y molecular sieve) is the earliest and is also one of the most important main active components of high-activity, high-stability and vanadium toxicity resistant catalytic cracking catalyst.

Most of sodium in the catalytic cracking catalyst is brought in by the molecular sieve, and a small part of sodium is brought in by the salt in the raw oil. The excessive existence of sodium ions can affect the thermal stability and selectivity of the catalyst, the toxic action is mainly reflected in that the sodium ions can neutralize the acid active centers of the catalyst, can react with hydrogen and rare earth on the molecular sieve to cause the active centers of the catalyst to be permanently inactivated, and can also form melts with metal oxides at high temperature to cause the crystal lattices of the molecular sieve to be damaged, thereby destroying the structure of the molecular sieve, reducing the specific surface area and causing the micro-counter activity to be reduced, and the toxic action can become more serious along with the increase of the temperature. Therefore, for preparing a catalytic cracking catalyst with excellent performance, the sodium content in the molecular sieve modified by ion exchange 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 content of residual sodium in the molecular sieve after ion exchange modification, the preparation of the rare earth Y type molecular sieve in industry is generally realized by adopting a mode of alternately carrying out multiple exchange and high-temperature roasting. However, in the existing traditional preparation process of "two-way and one-way baking" or "two-way and two-way baking", the rare earth ion exchange time is long, the production and preparation process is complicated, the production energy consumption is large, 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 catalytic cracking catalyst finished product can be reduced to below 0.2-0.3% index 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 propose a plurality of related modification methods. In order to achieve the required degree of exchange for the rare earth element ion by one-time exchange, researchers have studied and adopted the hot-pressing exchange method, but the long-time high-temperature and high-pressure exchange condition not only increases the energy consumption of production, but also may affect the crystal structure of the molecular sieve.

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

CN101088613A discloses a preparation method of REY molecular sieve, comprising the steps of contacting NaY molecular sieve with an aqueous solution containing rare earth ions or with an aqueous solution containing rare earth ions and a solution or colloid containing aluminum ions, adding a precipitator to enable partial rare earth ions to be precipitated on the molecular sieve, then roasting, and finally contacting with an ammonium salt solution. The method is simple and easy to implement, the preparation process 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 preparation method of a rare earth Y molecular sieve. Firstly mixing a NaY molecular sieve, a rare earth chloride solution and deionized water, then carrying out ion exchange, adding an oxalic acid solution into an exchange solution to completely precipitate the rare earth which is not exchanged, adding rare earth chloride and deionized water into a filtered filter cake to carry out ion exchange, and filtering to obtain the filter cake and a recycled filtrate. The filter cake is roasted by a muffle furnace to obtain a product REY molecular sieve, the recycled filtrate completely or partially replaces the rare earth chloride solution and enters the ion exchange process of the next batch of NaY molecular sieve, the utilization rate of rare earth almost reaches 100 percent, the production cost is reduced, REY with high rare earth content can be obtained, and the method has the advantages of high activity and high thermal stability.

CN1493402A discloses a mixed exchange method of ammonium and rare earth ions of a molecular sieve. The molecular sieve filter cake passes through the ion exchange area in sequence on the horizontal belt filter to complete the exchange, washing, filtering and roasting. The method can realize the exchange of ammonium salt and rare earth compound on the once-exchanged and once-baked Y-shaped molecular sieve at the same time, and has the advantages of low water consumption and high efficiency.

CN103058217A discloses a preparation method of a Y molecular sieve containing rare earth. Using NaY molecular sieve as raw material, firstly making ammonium exchange treatment, then making hydrothermal treatment at 550-750 deg.C, making the Y molecular sieve after the water vapour treatment contain H⁺、NH₄ ⁺、RE³⁺And 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 distribution of rare earth on the molecular sieve and strong vanadium resistance.

CN103130240A discloses a modified Y-type molecular sieve and its preparation method, which adopts the process of two-phase two-baking combined rare earth deposition, the modulation range of the slurry pH value in the rare earth deposition process in the preparation process is 6-10, the rare earth content of the obtained 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 the peak with 2 theta of 11.8 +/-0.1 degree in the X-ray diffraction spectrogram of the molecular sieve₁Intensity of peak 12.3 + -0.1 DEG with 2 theta₂Ratio of (I)₁/I₂) The product value of the weight percentage of the rare earth and the rare earth in the molecular sieve calculated by the rare earth oxide is more than 50. But the ammonia nitrogen content in the wastewater generated by the method is higher, and the environmental protection pressure is large.

In the prior art, no matter the one-cross one-baking, two-cross one-baking or two-cross two-baking process is adopted to prepare the rare earth Y-type molecular sieve, the preparation process is optimized to a certain extent in all aspects, or the production flow is simplified, or the utilization rate of rare earth is improved, or the stability of rare earth ions in the cage is improved. However, in general, the content of sodium oxide in the rare earth Y molecular sieve prepared by these methods is still relatively high, and washing operation is required in the subsequent preparation process of the catalyst cracking catalyst, which is not beneficial to the subsequent production, 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 and production process flow, high production energy consumption and the like of a molecular sieve containing rare earth elements in the prior art, and provides the molecular sieve containing the rare earth elements and a preparation method thereof. The preparation method of the rare earth element-containing molecular sieve provided by the invention is simple in process flow, and the prepared rare earth element-containing molecular sieve is low in sodium oxide content and good in hydrothermal stability.

In order to achieve the above objects, in one aspect, 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 a sodium type molecular sieve and a solution containing rare earth element ions to obtain a rare earth element ion exchanged molecular sieve;

2) roasting the molecular sieve subjected to the rare earth element ion exchange obtained in the step 1) to obtain a roasted molecular sieve;

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

Preferably, in step 1), the microwave conditions include: the microwave power is 0.01-100KW, the microwave heating time is 1-300min, the temperature is increased to the exchange temperature of 181-; more preferably, the microwave conditions include: the microwave power is 0.1-10KW, the microwave temperature rising time is 1-60min, the temperature is raised to the exchange temperature of 181-: the microwave power is 0.1-1.5KW, the microwave temperature-rising time is 5-30min, the temperature is raised to the exchange temperature of 181-.

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

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

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

Preferably, the rare earth element ions are derived from one or more of rare earth element hydrochlorides and rare earth element nitrates.

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 derived 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 the rare earth element ion exchange is dried and roasted.

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

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

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

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

Preferably, in the second ion exchange reaction, the weight ratio of the calcined molecular sieve 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 calcined molecular sieve 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 1-30 min; more preferably, the conditions of the second ion exchange reaction are: the exchange temperature is 15-80 deg.C, and the exchange time is 10-20 min.

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

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

Preferably, when the obtained rare earth element-containing molecular sieve is washed with an ammonium ion-containing solution after the second ion exchange reaction, the weight ratio of the rare earth element-containing molecular sieve to the ammonium ion source compound is 1: 0.01-1; more preferably, when the rare earth element-containing molecular sieve obtained after the second ion exchange reaction 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: and in the step 3), washing the molecular sieve containing the rare earth element obtained after the second ion exchange.

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

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

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 0.1-0.5 wt%.

Preferably, the rare earth element-containing molecular sieve contains 20-25 wt% of rare earth in terms of rare earth oxide.

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

At present, the content of sodium oxide in the rare earth Y molecular sieve prepared by adopting two-phase exchange and one-baking in industrial production is generally about 1.5-1.6 weight percent, while the content of residual sodium oxide in the rare earth element-containing molecular sieve prepared by adopting the method provided by the invention is far lower than the current industrial production level, and the rare earth Y 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 effect.

In addition, the prepared molecular sieve containing the rare earth elements has good hydrothermal stability, and particularly has higher micro-activity index and good cracking reaction activity after hydrothermal treatment at 800 ℃, 100% of water vapor and 4h and 17h, 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 of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For numerical ranges, each range between its endpoints and individual point values, and each individual point value can be combined with each other to give one or more new numerical ranges, and such numerical ranges should be construed as specifically disclosed herein.

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The invention provides a preparation method of a molecular sieve containing rare earth elements, wherein the method comprises the following steps:

The inventor of the invention finds that firstly, rare earth element ions are used for exchanging sodium ions in a sodium type molecular sieve under the microwave condition, and then ammonium ions are further used for exchanging residual sodium ions in the molecular sieve after roasting, so that the residual sodium content in the molecular sieve can be obviously reduced, and the rare earth element-containing molecular sieve with the residual sodium oxide content of less than 0.5 weight percent is obtained.

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

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

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

In the invention, the content of the sodium type molecular sieve in the aqueous solution containing the rare earth element ions can be changed in a large range, and preferably, the weight ratio of water in the aqueous solution to the sodium type molecular sieve in the first ion exchange reaction is 5-30: 1; more preferably, the weight ratio of water to sodium type molecular sieve in the aqueous solution during the first ion exchange reaction is from 8 to 20: 1. Although the treatment efficiency can be improved by increasing the amount of the sodium type molecular sieve, 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 present invention, the weight ratio of the rare earth element ion source compound to the sodium type molecular sieve in the aqueous solution containing the rare earth element ions at the time of the first ion exchange may also vary within a wide range, and it is preferable that the weight ratio of the rare earth element ion source compound to the sodium type molecular sieve in the aqueous solution at the time of the first ion exchange reaction is 0.02 to 1: 1; more preferably, the weight ratio of the rare earth ion source compound to the sodium type molecular sieve in the aqueous solution at the first ion exchange reaction is 0.2-0.8: 1; further preferably, the weight ratio of the rare earth ion source compound to the sodium type molecular sieve in the aqueous solution at the first ion exchange reaction is 0.4 to 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 is 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 β 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 rare earth element hydrochloride and a rare earth element nitrate.

As the rare earth element, 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 may be mentioned.

In a particularly preferred embodiment of the present invention, the rare earth element ions are 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 the sodium type 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: the microwave power is 0.01-100KW, the microwave heating time is 1-300min, the temperature is increased to the exchange temperature of 181-; preferably, the microwave conditions include: the microwave power is 0.1-10KW, the microwave temperature rise time is 1-60min, the temperature is raised to the exchange temperature of 181-; more preferably, the microwave conditions include: the microwave power is 0.1-1.5KW, the microwave temperature-rising time is 5-30min, the temperature is raised to the exchange temperature of 181-. By performing the first ion exchange between the rare earth element ions and the sodium ions in the molecular sieve under the above conditions, the ion exchange rate can be promoted, the ion exchange degree can be improved, and the content of the sodium ions in the molecular sieve can be reduced.

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

In the 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 can be preferably washed. Therefore, preferably, the method of the present invention comprises a step of washing the rare earth element ionic molecular sieve obtained in step 1).

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

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

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

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

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

According to the invention, the amount of molecular sieve obtained after calcination in step 2) may vary within wide limits with respect to the solution containing ammonium ions during the second ion exchange reaction. Preferably, the dosage of the molecular sieve obtained after the roasting in the step 2) is 50-400g/L relative to 1L of the solution containing ammonium ions; more preferably, the amount of the molecular sieve obtained after the calcination in step 2) is 100-350g/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 solution containing ammonium ions in the second ion exchange reaction may be determined according to the weight of the molecular sieve, and preferably, the weight ratio of the calcined molecular sieve of step 2) to the ammonium ion source compound in the solution containing ammonium ions in the second ion exchange reaction 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 solution containing ammonium ions is 1: 0.05-2; further preferably, in the second ion exchange reaction, the weight ratio of the calcined molecular sieve 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 ions are 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 the aqueous solution is added to the molecular sieve calcined in step 2) to perform the 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 1-30 min; preferably, the conditions of the second ion exchange reaction are: the exchange temperature is 15-80 ℃, and the exchange time is 5-30 min; more preferably, the conditions of the second ion exchange reaction are: the exchange temperature is 25-80 deg.C, and the exchange time is 10-20 min.

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

When the washing is carried out by using the solution containing the ammonium ions, the weight ratio of the molecular sieve containing the rare earth elements to the ammonium ion source compound is preferably 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, to further remove impurities in the obtained rare earth element-containing molecular sieve, preferably, the method further comprises: in the step 3), washing the rare earth element-containing molecular sieve obtained after the second ion exchange; when the water washing is carried out, the weight ratio of water to the molecular sieve is preferably 1-10: 1; more preferably, the weight ratio of water to molecular sieve is from 3 to 6: 1.

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

In addition, in the molecular sieve containing the rare earth elements, 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 below with reference to examples, but the present invention is not limited to the following examples.

In the following examples and comparative examples, NaY molecular sieves used were produced by chandeling division, petrochemical catalyst ltd, china.

In the following examples and comparative examples, the determination method of the content of rare earth oxide and residual sodium oxide in the molecular sieve is as follows: and uniformly grinding the dried powder sample, tabletting and forming, and measuring the contents of the rare earth oxide and the 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 type 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 is adjusted to 4.5 with dilute hydrochloric acid solution (5% strength by weight). Then placing the obtained mixed solution under the microwave condition to carry out first ion exchange, wherein the microwave condition comprises the following steps: the frequency is 2450MHz, the microwave power is 1.5KW, the temperature is raised from 25 ℃ to the exchange temperature of 220 ℃, the microwave temperature-raising time is 5min, and the temperature is kept for 5min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with 6 times of volume after the filtration, and then 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) at 550 ℃ for 3h to obtain a roasted molecular sieve;

3) mixing the roasted 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 roasting is 200g/L relative to 1L of the aqueous solution of ammonium chloride, the weight ratio of the ammonium chloride to the roasted molecular sieve obtained in the step 2) is 0.1:1, adjusting the pH 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 80 deg.C for 20min, and filtering after exchange;

4) ammonium washing the second ion exchanged molecular sieve obtained in the step 3) with an ammonium chloride aqueous solution, wherein the weight ratio of the molecular sieve to an ammonium ion source compound in the ammonium washing is 1:0.05, and then washing the obtained molecular sieve with 5 times of volume of deionized water to obtain the rare earth element-containing molecular sieve S-1, wherein the physicochemical properties of the molecular sieve are shown in Table 1, and the X-ray diffraction spectrum of the molecular sieve is shown in FIG. 1. As can be seen from FIG. 1, the crystal structure of the molecular sieve is not destroyed by performing rare earth ion exchange under the microwave condition, and characteristic diffraction peaks of rare earth ions located 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: the pH was adjusted to 4.5 with dilute hydrochloric acid solution (5% strength by weight). Then placing the obtained mixed solution under the microwave condition to carry out first ion exchange, wherein the microwave condition comprises the following steps: the frequency is 2450MHz, the microwave power is 0.5KW, the temperature is raised from 25 ℃ to the exchange temperature 181 ℃, the microwave temperature-raising time is 5min, and the temperature is kept for 25min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with 6 times of volume after the filtration, and then 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) at 550 ℃ for 2.5 hours to obtain a roasted molecular sieve;

3) mixing the roasted 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 roasting is 200g/L relative to 1L of the aqueous solution of ammonium chloride, the weight ratio of the ammonium chloride to the roasted molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH 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 25 deg.C for 20min, and filtering after exchange;

4) ammonium washing the molecular sieve obtained in the step 3) after the second ion exchange with an ammonium chloride aqueous solution, wherein the weight ratio of the molecular sieve to an ammonium ion source compound in the ammonium washing is 1:0.01, and then washing the obtained molecular sieve with 5 times of volume of deionized water to obtain the molecular sieve S-2 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve S-2 are shown in 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: the pH is adjusted to 4 with dilute hydrochloric acid solution (5% strength by weight). Then placing the obtained mixed solution under the microwave condition to carry out first ion exchange, wherein the microwave condition comprises the following steps: the frequency is 2450MHz, the microwave power is 1KW, the temperature is increased from 25 deg.C to 190 deg.C, the microwave temperature-increasing time is 5min, and the temperature is maintained at the exchange temperature for 20 min. Filtering after the exchange is finished, washing the obtained product by using deionized water with 6 times of volume after the filtration, and then 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) at 550 ℃ for 2h to obtain a roasted molecular sieve;

3) mixing the roasted 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 roasting is 200g/L relative to 1L of the aqueous solution of ammonium chloride, the weight ratio of the ammonium chloride to the roasted molecular sieve obtained in the step 2) is 0.1:1, adjusting the pH 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 60 deg.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 5 times of volume to obtain the molecular sieve S-3 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve S-3 are shown in 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: the pH was adjusted to 4.5 with a dilute hydrochloric acid solution (10% by weight). Then placing the obtained mixed solution under the microwave condition to carry out first ion exchange, wherein the microwave condition comprises the following steps: the frequency is 2450MHz, the microwave power is 0.3KW, the temperature is increased from 25 ℃ to 190 ℃ and the microwave temperature-increasing time is 5min, and the temperature is kept for 15min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with 6 times of volume after the filtration, and then drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

3) mixing the calcined 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 calcination is 200g/L relative to 1L of the aqueous solution of ammonium sulfate, the weight ratio of the ammonium sulfate to the calcined molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH 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 45 deg.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 5 times of volume to obtain the molecular sieve S-4 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve are shown in 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: the pH was adjusted to 4.5 with dilute hydrochloric acid solution (5% strength by weight). Then placing the obtained mixed solution under the microwave condition to carry out first ion exchange, wherein the microwave condition comprises the following steps: the frequency is 2450MHz, the microwave power is 0.2KW, the temperature is increased from 25 ℃ to 190 ℃ and the microwave temperature-increasing 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 6 times of volume after the filtration, and then drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

3) mixing the calcined molecular sieve obtained in the step 2) with an aqueous solution containing ammonium sulfate, wherein the dosage of the molecular sieve obtained after the calcination in the step 2) is 200g/L relative to 1L of the aqueous solution of ammonium sulfate, the weight ratio of the ammonium sulfate to the calcined molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH 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 30 deg.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 5 times of volume 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 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 the lanthanum chloride to the NaY molecular sieve is 0.4: the pH was adjusted to 4.5 with dilute hydrochloric acid solution (5% strength by weight). Then placing the obtained mixed solution under the microwave condition to carry out first ion exchange, wherein the microwave condition comprises the following steps: the frequency is 2450MHz, the microwave power is 0.1KW, the temperature is raised from 25 ℃ to the exchange temperature of 185 ℃, the microwave temperature-raising time is 5min, and the temperature is kept for 8min at the exchange temperature. Filtering after the exchange is finished, washing the obtained product by using deionized water with 6 times of volume after the filtration, and then drying for 6 hours at 120 ℃ to obtain the molecular sieve after the rare earth element ion exchange;

3) mixing the calcined molecular sieve obtained in the step 2) with an aqueous solution containing ammonium sulfate, wherein the dosage of the molecular sieve obtained after the calcination in the step 2) is 200g/L relative to 1L of the aqueous solution of ammonium sulfate, the weight ratio of the ammonium sulfate to the calcined molecular sieve obtained in the step 2) is 0.05:1, adjusting the pH 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 15 deg.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 5 times of volume to obtain the molecular sieve S-6 containing the rare earth elements, wherein the physicochemical properties of the molecular sieve are shown in Table 1.

Comparative example 1

The procedure is as in example 1, except that:

the conventional two-way one-way baking method is adopted, namely, in the step 1), the conditions of the first ion exchange comprise: heating the obtained mixed solution from 25 deg.C to exchange temperature of 220 deg.C by electric heating, heating for 120min, and maintaining at the exchange temperature for 5 min. The molecular sieve D-1 containing rare earth elements is obtained, and the physicochemical properties are shown in Table 1.

Comparative example 2

The procedure is as in example 1, except that:

step 3) and step 4) are not carried out, and the molecular sieve D-2 containing rare earth elements is obtained after roasting, wherein the physicochemical properties of the molecular sieve D-2 are shown in Table 1.

TABLE 1

Product numbering	S-1	S-2	S-3	S-4	S-5	S-6	D-1	D-2
									Na₂O content (% by weight)	0.12	0.20	0.35	0.42	0.48	0.5	1.6	2.0
Re₂O₃Content (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 molecular sieve containing rare earth elements prepared by the method provided by the invention has far lower residual sodium oxide content than that of the conventional two-way one-way roasting product (D-1) and higher thermal stability.

Test example

1) Sample pretreatment: the rare earth element-containing molecular sieve samples D-1 and D-2 obtained in the comparative example were subjected to ion exchange repeatedly with an aqueous ammonium chloride solutionAnd washing until Na in the D-1 and D-2 molecular sieves₂The content of O is less than 0.5 wt%, wherein, during ion exchange, the weight ratio of the molecular sieve to the ammonium chloride to the water is 1: 0.3: 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 treated molecular sieves D-1 'and D-2' containing rare earth elements.

2) Hydrothermal aging of a sample: the molecular sieves containing the rare earth elements and the molecular sieves D-1 'and D-2' containing the rare earth elements prepared in the examples 1 to 6 were subjected to 100% steam aging by using a rotary evaporation aging apparatus, wherein the aging temperature was 800 ℃, the aging time was 4 hours and 17 hours, respectively, and the water inlet rate was 1.8 g/min.

3) Micro activity index test: 5 g of the molecular sieve containing the rare earth element and the molecular sieves D-1 'and D-2' containing the rare earth element, which are prepared in the step 2) through hydrothermal aging treatment in the embodiment 1-6, are put into a standard microreactor with the bed temperature controlled at 460 ℃, 1.56 g of standard raw oil is injected into a reactor at a constant speed within 70 seconds for reaction, then nitrogen is used for purging for 10 minutes, the reaction product is collected in a bottle, the collection bottle is placed in a cold trap mixed with ice water, the liquid phase reaction product is analyzed through gas chromatography, and the micro-activity index of each molecular sieve sample is calculated according to the analysis data: micro-activity (MA) is [ 1-liquid oil recovery quality x (1-percentage content of gasoline component in liquid oil recovery)/standard oil quality ] x 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 ℃ -4h)	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 molecular sieve containing rare earth elements prepared by the method provided by the present invention has significantly better hydrothermal stability and retains stronger catalytic cracking activity after undergoing severe hydrothermal treatment compared with the product prepared by the conventional two-way and one-way roasting process.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims

1. A method for preparing a molecular sieve containing rare earth elements is characterized by comprising the following steps:

2. The preparation method according to claim 1, wherein the microwave conditions in step 1) include: the microwave power is 0.01-100KW, the microwave heating time is 1-300min, the temperature is increased to the exchange temperature of 181-;

preferably, the microwave conditions include: the microwave power is 0.1-10KW, the microwave temperature rise time is 1-60min, the temperature is raised to the exchange temperature of 181-,

more preferably, the microwave conditions include: the microwave power is 0.1-1.5KW, the microwave temperature-rising time is 5-30min, the temperature is raised to the exchange temperature of 181-.

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

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

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

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

more preferably, the weight ratio of the rare earth ion source compound to the sodium type molecular sieve in the aqueous solution at the first ion exchange reaction is 0.2-0.8: 1;

further preferably, the weight ratio of the rare earth ion source compound to the sodium type molecular sieve in the aqueous solution at the first ion exchange reaction is 0.4 to 0.8: 1.

4. The method according to any one of claims 1 to 3, 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 molecular sieve;

preferably, the sodium type molecular sieve is selected from Y type molecular sieves;

preferably, the rare earth element ions are derived from one or more of rare earth element hydrochloride and rare earth element nitrate;

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 derived from one or more of lanthanum chloride, cerium chloride, lanthanum nitrate and cerium nitrate.

5. The method according to any one of claims 1-3, wherein the method further comprises: in the step 2), drying and roasting the molecular sieve obtained in the step 1) after the rare earth element ion exchange;

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

6. The method according to any one of claims 1 to 3, wherein in step 3), the solution containing ammonium ions is an aqueous solution, and the pH of the solution is 3 to 6 during the second ion exchange reaction;

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

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

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

7. The method according to any one of claims 1 to 3, wherein in step 3), the conditions of the second ion exchange reaction are: the exchange temperature is 5-90 ℃, and the exchange time is 1-30 min;

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

preferably, the ammonium ions are derived from one or more of ammonium chloride, ammonium nitrate, ammonium sulfate, ammonium oxalate and ammonium carbonate;

preferably, the ammonium ions are from one or more of ammonium chloride, ammonium sulfate and ammonium nitrate.

8. The method according to any one of claims 1-3, wherein the method further comprises: in the step 3), after the second ion exchange reaction, washing the obtained molecular sieve containing the rare earth element by using a solution containing ammonium ions;

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

more preferably, when the rare earth element-containing molecular sieve obtained after the second ion exchange reaction 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.

9. The method according to any one of claims 1-3, wherein the method further comprises: in the step 3), washing the rare earth element-containing molecular sieve obtained after the second ion exchange;

more preferably, the weight ratio of water to the molecular sieve obtained after the second ion exchange in the water washing is 1-10: 1;

further preferably, the weight ratio of water to the molecular sieve obtained after the second ion exchange in the water washing is 3-6: 1.

10. A rare earth element-containing molecular sieve produced by the method for producing a rare earth element-containing molecular sieve according to any one of claims 1 to 9;

preferably, the molecular sieve containing the rare earth element is a Y-type molecular sieve;

preferably, in the rare earth element-containing molecular sieve, the content of sodium oxide is 0.1-0.5 wt%;