WO2024060868A1

WO2024060868A1 - Modified molecular sieve, preparation method therefor, and use thereof

Info

Publication number: WO2024060868A1
Application number: PCT/CN2023/112206
Authority: WO
Inventors: 段宏昌; 刘涛; 胡晓丽; 苏怡; 谭争国; 景丽; 曹庚振; 陆通; 刘超伟; 郑云锋
Original assignee: 中国石油天然气股份有限公司
Priority date: 2022-09-20
Filing date: 2023-08-10
Publication date: 2024-03-28
Also published as: CN117776204A

Abstract

The present invention relates to the technical field of molecular sieves, and in particular to a preparation method for a modified molecular sieve, a modified molecular sieve prepared by the preparation method, and use of the modified molecular sieve. The preparation method comprises: (1) subjecting a Na-type molecular sieve to metal ion exchange to obtain a metal ion slurry; (2) adding a first precipitant to allow part of metal ions in the metal ion exchange slurry to be subjected to first precipitation to obtain a first precipitation slurry; (3) subjecting the first precipitation slurry to filtering, first ammonium sulfate exchange, first water washing, and first roasting sequentially to obtain a one-exchange one-roasting molecular sieve dry powder; and (4) adding a second precipitant to allow part of metal ions in the one-exchange one-roasting molecular sieve dry powder to be subjected to second precipitation, and then carrying out second ammonium sulfate exchange, second water washing, and optional second roasting sequentially to obtain the modified molecular sieve. The modified molecular sieve prepared by the method has relatively low sulfate radical content, and the crystallinity and stability of the modified molecular sieve are improved.

Description

Modified molecular sieve and its preparation method and application

Cross-references to related applications

This application claims the rights and interests of Chinese patent application 202211148910.5 submitted on September 20, 2022. The contents of this application are incorporated herein by reference.

Technical field

The present invention relates to the technical field of molecular sieves, and in particular to a preparation method of modified molecular sieves, a modified molecular sieve prepared by the preparation method and its application.

Background technique

The catalytic cracking reaction is a typical acid-catalyzed gas-solid heterogeneous reaction that follows the carbon ion mechanism. NaY molecular sieve itself is not acidic and usually requires exchange modification to remove Na ions and modulate its acidity and pore structure. Because the acid H ⁺ is too acidic, it is easy to destroy the Y-type molecular sieve skeleton structure, resulting in a decrease in crystallinity and selectivity. However, the REY-type molecular sieve is prone to coke and deactivation during the catalytic cracking reaction due to its excessive acidity and acid density. Therefore, the currently commonly used modification method is to use ammonium salts or/and rare earths for exchange, and then prepare modified REHY or REUSY molecular sieves with different acidities and pore structures through thermal or hydrothermal roasting.

Ammonium chloride is easy to decompose at high temperatures and crystallize at low temperatures, so it is easy to block the catalyst flue and bag dust collector, resulting in the inability to produce continuously; while ammonium nitrate is susceptible to high temperature, high pressure, the presence of oxidizable substances (reducing agents), and sparks. It will explode and is a key raw material for making explosives. It is expensive and therefore is not used. Ammonium sulfate is stable and cheap. It is often used for exchange modification of industrial molecular sieves. However, because it easily forms rare earth sulfate precipitation with rare earths, it is difficult to use it. On the one hand, rare earth ions cannot migrate into the cage of the molecular sieve, effectively stabilizing the molecular sieve skeleton structure. On the other hand, it can easily cause excessive sulfate radicals, destroying the molecular sieve skeleton structure, and the sulfate radicals will be converted into sulfides during the oil refining process after being made into catalysts. , corrosion equipment.

In the existing technology, the method of precipitating rare earths is often used to improve the utilization rate of rare earths, and at the same time generate independent phase rare earths to improve the anti-V pollution performance of molecular sieves; rare earths and ammonium salts are exchanged at the same time, and due to competitive exchange, the exchange efficiency is low; Ammonium salt exchange is carried out before rare earth exchange. The use of ammonium chloride and ammonium nitrate will cause problems such as high cost and equipment corrosion. However, the use of low-cost and recyclable ammonium sulfate requires a large amount of water washing to remove sulfate precipitation in order to avoid the formation of sulfate precipitation. Sulfate radicals will also cause increased water consumption. After hydrothermal roasting of rare earth-modified molecular sieves, it is inevitable that some rare earths cannot be positioned in the sodalite gabion, so ammonium sulfate exchange is used in the subsequent process, resulting in the formation of rare earth sulfate precipitation, resulting in an increase in sulfate radicals in the molecular sieve and a decrease in crystallinity. Although pre-exchange can reduce the sodium oxide and sulfate radicals of modified molecular sieves, it has the problems of long process, water consumption and high cost. REY molecular sieves prepared without ammonium salts have the problem of high coke generation.

CN200610087535.2 discloses a preparation method of REY molecular sieve. The method includes: contacting the 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, and then contacting it with an external precipitant. Part of the rare earth is precipitated on the molecular sieve, and then hydrothermally treated, and finally contacted with an ammonium salt solution. The prepared molecular sieve has strong vanadium resistance. Although rare earth exchange, precipitation, filtration, and roasting are used to prepare a cross-baked rare earth modified Y-type molecular sieve, and then the ammonium salt exchange is directly performed to obtain REY molecular sieve, although the loss of rare earth is avoided through precipitation during the first cross-crossing process, Due to the cross-baked rare earth modified Y-type molecular sieve, the rare earth will inevitably exist on the outer surface of the molecular sieve or in the supercage space. If ammonium sulfate is used as the exchange agent later, this part of the rare earth will easily form rare earth sulfate precipitation with sulfate radicals, resulting in the molecular sieve High sulfate, low crystallinity, and poor stability.

CN201511020519.7 discloses a method for preparing a modified Y-type molecular sieve. The method includes: exchanging NaY molecular sieve with ammonium salt first, filtering and mixing compounds containing IIIB elements of the periodic table, spray drying and water directly without washing. Thermal roasting, then exchange with ammonium salt, add precipitant or precipitant and filter aid, and perform hydrothermal roasting with or without filtration. Although this method mixes and roasts the ammonium salt-exchanged molecular sieve filter cake with IIIB element compounds, and at the same time adds a precipitant after the diacrotium salt exchange to avoid the loss of IIIB element compounds, it also after one cross-baking, Directly exchange with ammonium salt, if ammonium sulfate is used as As an exchange agent, this part of IIIB elements easily reacts with sulfate to form rare earth sulfate precipitation, resulting in high sulfate, low crystallinity and poor stability of the molecular sieve.

Therefore, a new method for preparing modified molecular sieves is urgently needed.

Contents of the invention

The purpose of the present invention is to overcome the problems of high sulfate, low crystallinity, equipment corrosion, long production process, high cost and other problems in the existing preparation methods of modified molecular sieves, and provide a preparation method of modified molecular sieves. The modified molecular sieve prepared by the preparation method and its application. The modified molecular sieve prepared by the preparation method has the characteristics of low sulfate content, high crystallinity, good stability, etc. At the same time, the method simplifies the process flow and facilitates industrial production.

In order to achieve the above object, the first aspect of the present invention provides a preparation method of modified molecular sieve, the preparation method includes the following steps:

(1) Perform metal ion exchange on Na-type molecular sieve to obtain a metal ion slurry;

(2) Add a first precipitating agent to cause part of the metal ions in the metal ion exchange slurry to undergo first precipitation to obtain a first precipitation slurry;

(3) The first precipitation slurry is sequentially subjected to filtration, first ammonium sulfate exchange, first water washing, and first roasting to obtain a cross-baked molecular sieve dry powder;

(4) Add a second precipitating agent to cause a second precipitation of some metal ions in the cross-baked molecular sieve dry powder, and then sequentially perform a second ammonium sulfate exchange, a second water washing, and an optional second roasting to obtain modification Molecular sieves.

A second aspect of the present invention provides a modified molecular sieve prepared by the preparation method provided in the first aspect.

A third aspect of the present invention provides an application of the modified molecular sieve provided in the second aspect in heavy oil conversion and resistance to heavy metal vanadium pollution.

Compared with the existing technology, the present invention has the following advantages:

(1) The preparation method of the modified molecular sieve provided by the present invention is by placing the Na-type molecular sieve in a metal ion interaction After the exchange and before the ammonium sulfate exchange, add a precipitant (i.e., the first precipitant and the second precipitant) to generate a precipitation precursor of the metal oxide with the metal ions to avoid the exchange system during the subsequent ammonium sulfate exchange and sodium reduction process. Free metal ions and sulfate radicals in the solution, on the molecular sieve surface or in the supercage form precipitates, thereby achieving the purpose of reducing sulfate radicals;

(2) The preparation method provided by the invention also improves the crystallinity and stability of the modified molecular sieve, improves metal utilization, generates independent phase multivalent metal oxides, and improves heavy oil conversion capacity and resistance to heavy metal vanadium pollution. capability; at the same time, the preparation method is simple to operate, simplifies the process flow, and facilitates industrial production.

Detailed ways

The endpoints and any values of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoint values of each range, the endpoint values of each range and the individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed in this article.

In the present invention, unless otherwise specified, "first" and "second" neither indicate a sequence nor a limitation on each material or step, and are only used to distinguish that these are not the same step or material. For example, the "first" and "second" in "first ammonium sulfate exchange" and "second ammonium sulfate exchange" are only used to indicate that this is not the same ammonium sulfate exchange.

A first aspect of the present invention provides a method for preparing modified molecular sieves. The preparation method includes the following steps:

(4) Add a second precipitating agent to allow part of the metal ions in the cross-baked molecular sieve dry powder to undergo a second Precipitate, and then perform the second ammonium sulfate exchange, the second water washing, and the optional second roasting in sequence to obtain the modified molecular sieve.

In some embodiments of the present invention, preferably, in step (1), the metal ion exchange conditions include: temperature is 25-180°C, preferably 50-80°C; pH is 2.8-6.5, preferably 3.5 -4.5; time is 0.3-3.5h, preferably 0.5-1.5h.

In some embodiments of the present invention, preferably, the metal ion exchange process includes: mixing the Na-type molecular sieve and water, and then adding a soluble metal salt to perform the metal ion exchange.

In some embodiments of the present invention, preferably, the weight ratio of the Na-type molecular sieve and water is 1:1.5-30, for example, 1:1.5, 1:2, 1:3, 1:4, 1:5 , 1:10, 1:20, 1:30, and any value in the range of any two numerical values, preferably 1:2-5.

In some embodiments of the present invention, preferably, the content of the soluble metal salt calculated as oxide in the Na-type molecular sieve on a dry basis is 1-20wt%, for example, 1wt%, 4wt%, 6wt%, 8wt%, 10wt%, 12wt%, 14wt%, 16wt%, 20wt%, and any value in the range of any two numerical values, preferably 6-16wt%. Using optimal conditions is more conducive to reducing the sulfate content in the modified molecular sieve, thereby eliminating the impact of sulfate on the performance of the modified molecular sieve, and improving the crystallinity and catalytic performance of the modified molecular sieve.

In the present invention, during the metal ion exchange process, the metal ions in the soluble metal salt are completely attached to the surface and internal pores of the Na-type molecular sieve. Therefore, the weight ratio of the Na-type molecular sieve on a dry basis and the soluble metal salt on an oxide basis is 100:1-20, preferably 100:6-16.

In the present invention, unless otherwise stated, solubility refers to being easily soluble in water or easily soluble in water under the action of additives.

In some embodiments of the present invention, preferably, the soluble metal salt is selected from chlorates and/or nitrates containing at least one of rare earth elements, alkaline earth metal elements, and transition metal elements, preferably selected from chlorates and/or nitrates containing at least one of rare earth elements, alkaline earth metal elements, and transition metal elements. The chlorate and/or nitrate of rare earth elements is more preferably selected from lanthanum chloride and/or lanthanum nitrate. In the present invention, the alkaline earth metal element is selected from calcium and/or barium; the transition metal element is selected from silver and/or lead.

In the present invention, the type of Na-type molecular sieve has a wide selection range. Preferably, the The silicon-to-aluminum ratio of the Na-type molecular sieve is 2-100, preferably 2-50; further preferably, the Na-type molecular sieve is selected from the group consisting of NaY molecular sieve, NaHY molecular sieve, NaUSY molecular sieve, NaREHY molecular sieve, NaREUSY molecular sieve, Naβ molecular sieve, NaHβ molecular sieve, At least one of NaREHβ molecular sieve, NaX molecular sieve, NaREX molecular sieve and NaHX molecular sieve is preferably selected from NaY molecular sieve and/or NaHY molecular sieve, more preferably NaY molecular sieve.

In some embodiments of the present invention, preferably, in step (2), the amount of the first precipitating agent satisfies the mole content of 1-4 wt% of metal ions in the Na-type molecular sieve after the first precipitation. Proportion; further preferably, the amount of the first precipitating agent satisfies the molar proportion of the first precipitation of metal ions with a content of 1.5-2.5 wt% in the Na-type molecular sieve. Using optimal conditions is more conducive to reducing the sulfate content of the modified molecular sieve, thereby improving the crystallinity and catalytic performance of the modified molecular sieve.

In the present invention, the type of the first precipitating agent has a wide selection range, as long as the metal ions are converted into metal oxides. Preferably, the first precipitating agent is selected from at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate, ammonia, urea and ammonium acetate, preferably at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate and ammonia. A sort of.

In some embodiments of the present invention, preferably, the conditions for the first precipitation include: temperature is 25-180°C, preferably 50-80°C; time is 0.1-5h, preferably 0.1-2h.

In the present invention, the first ammonium sulfate exchange is intended to further exchange Na ⁺ in the Na-type molecular sieve. Preferably, in step (3), the first ammonium sulfate exchange process includes: exchanging the filtered product and the first ammonium sulfate aqueous solution.

In some embodiments of the present invention, preferably, the weight ratio of the first ammonium sulfate aqueous solution and Na-type molecular sieve calculated as ammonium sulfate is 5-50:100, for example, 5:100, 10:100, 15: 100, 20:100, 25:100, 30:100, 40:100, 50:100, and any value in the range of any two values, preferably 10-25:100.

In some embodiments of the present invention, preferably, the concentration of ammonium sulfate in the first ammonium sulfate aqueous solution 20-400g/L, for example, 20g/L, 50g/L, 80g/L, 120g/L, 150g/L, 200g/L, 250g/L, 300g/L, 400g/L, and any two values Any value within the composition range is preferably 120-250 g/L.

In some embodiments of the present invention, preferably, the conditions for the first ammonium sulfate exchange include: temperature is 15-150°C, preferably 50-80°C; time is 0.1-5h, preferably 0.5-2h.

In some embodiments of the present invention, preferably, the amount of water used in the first water wash is 1-8 times the weight of the Na-type molecular sieve, for example, 1 times, 2 times, 3 times, 4 times, 5 times, 8 times, and any value in the range of any two values, preferably 2-5 times.

In some embodiments of the present invention, preferably, the conditions for the first roasting include: 100% water vapor atmosphere; temperature is 400-700°C, preferably 500-650°C; time is 0.1-5h, preferably 0.5 -3h.

In some embodiments of the present invention, preferably, the amount of the second precipitant satisfies the molar ratio of the metal ions in the cross-roasted molecular sieve dry powder of 0.5-3wt% through the second precipitation; further preferably, the amount of the second precipitant satisfies the molar ratio of the metal ions in the cross-roasted molecular sieve dry powder of 1-2wt% through the second precipitation. The use of the preferred conditions is more conducive to reducing the sulfate content of the modified molecular sieve, thereby improving the crystallinity and catalytic performance of the modified molecular sieve.

In some embodiments of the present invention, preferably, the second precipitant is selected from at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate, ammonia water, urea and ammonium acetate, preferably selected from at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate and ammonia water.

In some embodiments of the present invention, preferably, the conditions for the second precipitation include: temperature is 15-40°C, preferably 20-30°C; time is 0.1-5h, preferably 0.1-2h.

In some embodiments of the present invention, preferably, in step (4), the second ammonium sulfate exchange process includes: exchanging the second precipitation product and the second ammonium sulfate aqueous solution.

In some embodiments of the present invention, preferably, the weight ratio of the second ammonium sulfate aqueous solution and cross-baked molecular sieve dry powder calculated as ammonium sulfate is 5-50:100, for example, 5:100, 10:100 , 15:100, 20:100, 25:100, 30:100, 40:100, 50:100, and any value in the range of any two values, preferably for 10-25:100.

In some embodiments of the present invention, preferably, the concentration of ammonium sulfate in the second aqueous ammonium sulfate solution is 20-400 g/L, for example, 20 g/L, 50 g/L, 80 g/L, 120 g/L, 150 g/L, 200 g/L, 250 g/L, 300 g/L, 400 g/L, and any value in the range consisting of any two values, preferably 120-250 g/L.

In some embodiments of the present invention, preferably, the conditions for the second ammonium sulfate exchange include: temperature is 20-85°C, preferably 50-80°C; time is 0.1-5h, preferably 0.1-2h.

In some embodiments of the present invention, preferably, the amount of water used in the second water washing is 1-8 times the weight of the cross-baked molecular sieve dry powder, for example, 1 time, 2 times, 3 times, 4 times times, 5 times, 8 times, and any value in the range consisting of any two numerical values, preferably 2-5 times.

In some embodiments of the present invention, preferably, the conditions for the second roasting include: 20-100% water vapor atmosphere; temperature 400-700°C, preferably 450-650°C; time 0.1-10h, preferably is 0.5-5h.

In some embodiments of the present invention, preferably, before the second precipitation, the cross-baked molecular sieve dry powder and water are mixed.

In some embodiments of the present invention, preferably, in step (4), the weight ratio of the cross-baked molecular sieve dry powder to water is 1:1.5-30, for example, 1:1.5, 1:2, 1:3, 1:4, 1:5, 1:10, 1:20, 1:30, and any value in the range consisting of any two values, preferably 1:2-5.

The modified molecular sieve prepared by the preparation method provided by the invention has low sulfate content, high crystallinity, good stability, etc., and has high activity in heavy oil conversion and resistance to medium metal vanadium pollution.

In some embodiments of the present invention, preferably, the modified molecular sieve satisfies: SO ₄ ^2- content ≤ 0.5 wt%, preferably 0.01-0.45 wt%.

In some embodiments of the present invention, preferably, the modified molecular sieve has a Na ₂ O content of ≤1 wt%, and a RE ₂ O ₃ content of ≥5 wt%; further preferably, the modified molecular sieve has a Na ₂ O content of 0.5-1 wt%, and a RE ₂ O ₃ content of 10-20 wt%.

In some embodiments of the present invention, preferably, the crystallinity C/C ₀ of the modified molecular sieve is ≥50%, preferably 55-75%.

In the present invention, unless otherwise specified, the SO ₄ ^2- content parameter is measured by XRF fluorescence method; the crystallinity parameter is measured by X-ray diffraction method; the micro-reaction activity parameter is tested as follows: the sample is pre-treated at 800°C and 100% water vapor for different times; the reaction raw material is Dagang light diesel, the reaction temperature is 460°C, the reaction time is 70s, the catalyst loading is 5g, the catalyst-oil weight ratio is 3.2, and the total conversion rate is taken as the micro-reaction activity.

According to a particularly preferred embodiment of the present invention, a method for preparing a modified molecular sieve comprises the following steps:

(4) Add a second precipitating agent to cause a second precipitation of some metal ions in the cross-baked molecular sieve dry powder, and then sequentially perform a second ammonium sulfate exchange, a second water washing, and an optional second roasting to obtain modification molecular sieve;

Wherein, in step (2), the amount of the first precipitating agent satisfies the molar ratio of the first precipitation of metal ions with a content of 1.5-2.5 wt% in the Na-type molecular sieve;

Wherein, in step (3), the conditions for the first roasting include: 100% water vapor atmosphere; temperature 500-650°C; time 0.5-3h;

Wherein, in step (4), the amount of the second precipitating agent satisfies the molar ratio of the second precipitation of metal ions with a content of 1-2wt% in the cross-baked molecular sieve dry powder; the second The conditions for roasting include: 20-100% water vapor atmosphere; temperature 450-650°C; time 0.5-5h.

The present invention will be described in detail below through examples.

NaY molecular sieve was purchased from Lanzhou Catalyst Factory;

SO ₄ ^2- content parameters were measured using XRF fluorescence method;

Crystallinity parameters were measured using X-ray diffraction method;

The micro-reaction parameter test is as follows: the sample is pre-treated at 800°C and 100% water vapor for different times; the reaction raw material is Dagang light diesel oil, the reaction temperature is 460°C, the reaction time is 70s, the catalyst loading is 5g, and the agent-to-oil weight ratio is 3.2. The total conversion rate was used as the microreaction activity.

The physical property parameters of the modified molecular sieves (Z1-Z7 and DZ1-DZ4) prepared in Examples 1-7 and Comparative Examples 1-4 are listed in Table 1.

Example 1

(1) After beating 1000 grams of NaY molecular sieve (dry basis weight) with 5L of deionized water, add 0.537L (calculated as La ₂ O ₃ ) of a LaCl ₃ solution with a concentration of 298g/L (La ³⁺ is 0.98 mol) Carry out metal ion exchange (temperature: 80°C, time: 0.5h) to obtain a metal ion exchange slurry; wherein the content of LaCl ₃ calculated as La ₂ O ₃ in the NaY molecular sieve calculated on a dry basis is 16 wt%;

(2) Add (32g, 0.225mol) ammonium oxalate monohydrate to cause 2.4wt% La ³⁺ in the above metal ion exchange slurry to undergo first precipitation (temperature: 80°C, time: 0.5h) to obtain the first precipitation slurry ;

(3) The first precipitate slurry was filtered and drained, 0.833 L of 180 g/L ammonium sulfate aqueous solution was added, exchanged at 60° C. for 1 h, drained, rinsed with 3 L of water, and then calcined at 500° C. for 2 h in a 100% water vapor atmosphere to obtain a cross-linked and roasted molecular sieve dry powder;

(4) Beat the above 1000g (dry basis weight) cross-baked molecular sieve dry powder with 5L deionized water, then add (25.6g, 0.18mol) ammonium oxalate monohydrate, so that the above cross-baked molecular sieve dry powder After the second precipitation of 2wt% La ³⁺ (temperature: 25°C, time: 0.5h), add 0.6L ammonium sulfate aqueous solution with a concentration of 250g/L, exchange at 80°C for 1.5h, filter, drain, and add 5L Water rinse, 450℃ in 100% water vapor atmosphere After roasting for 2 hours, modified molecular sieve Z1 was obtained.

Example 2

(1) After beating 1000 grams of NaY molecular sieve (dry basis weight) with 5L of deionized water, add 0.358L of La(NO ₃ ) ₃ solution (La ³⁺ ) with a concentration of 280g/L (calculated as La ₂ O ₃ ) (0.615 mol) for metal ion exchange (temperature: 50°C, time: 1.5h) to obtain a metal ion exchange slurry; wherein, La (NO ₃ ) ₃ calculated as La ₂ O ₃ is on a dry basis NaY molecular sieve Content is 10wt%;

(2) adding (25.6 g, 0.18 mol) of ammonium oxalate monohydrate to allow 2 wt % of La ³⁺ in the metal ion exchange slurry to undergo a first precipitation (temperature of 50° C., time of 0.5 h) to obtain a first precipitation slurry;

(3) Filter the above-mentioned first precipitation slurry, drain it, add 1.111L ammonium sulfate aqueous solution with a concentration of 180g/L, exchange it at 80°C for 1 hour, drain it, add 3L water to rinse, and then rinse it in a 100% water vapor atmosphere. Roast at 600°C for 2 hours to obtain cross-roasted molecular sieve dry powder;

(4) The above 1000 g (dry basis) cross-linked and roasted molecular sieve powder was slurried with 5 L of deionized water, and then (13 g, 0.135 mol) of ammonium carbonate was added to allow 1.5 wt% of La ³⁺ in the above cross-linked and roasted molecular sieve powder to undergo a second precipitation (temperature of 25°C, time of 0.5 h). Then, 1.666 L of 120 g/L ammonium sulfate aqueous solution was added, exchanged at 50°C for 1 h, filtered, drained, rinsed with 2 L of water, and calcined at 500°C in an 80% water vapor atmosphere for 2.5 h to obtain a modified molecular sieve Z2.

Example 3

(1) After beating 1000 grams of NaY molecular sieve (dry basis weight) with 5L of deionized water, add 0.336L of LaCl ₃ solution (La ³⁺ is 0.615 mol) with a concentration of 298g/L (calculated as La ₂ O ₃ ) Carry out metal ion exchange (temperature: 50°C, time: 1h) to obtain a metal ion exchange slurry; wherein the content of LaCl ₃ calculated as La ₂ O ₃ in the NaY molecular sieve calculated on a dry basis is 10wt%;

(2) Add 16mL of 28% industrial ammonia water to make 1.5wt% of La ³⁺ in the above metal ion exchange slurry. Perform the first precipitation (temperature: 50°C, time: 0.5h) to obtain the first precipitation slurry;

(3) Filter the above first precipitation slurry, drain it, add 1.389L ammonium sulfate aqueous solution with a concentration of 180g/L, exchange it at 50°C for 1.5 hours, drain it, add 3L water to rinse, and then rinse it in 100% water vapor Roast at 650°C for 2 hours in the atmosphere to obtain cross-roasted molecular sieve dry powder;

(4) Beat the above 1000g (dry basis weight) cross-baked molecular sieve dry powder with 5L deionized water, then add (12.8g, 0.09mol) ammonium oxalate monohydrate, so that the above cross-baked molecular sieve dry powder After the second precipitation of 1wt% La ³⁺ (temperature: 25°C, time: 0.5h), add 1.389L ammonium sulfate aqueous solution with a concentration of 180g/L, exchange at 50°C for 1h, filter, drain, and add 3L water Rinse and roast at 650°C for 2 hours in a 60% water vapor atmosphere to obtain modified molecular sieve Z3.

Example 4

(1) After beating 1000 grams of NaY molecular sieve (dry basis weight) with 5L of deionized water, add 0.43L of mixed RECl ₃ solution (Ce ₂ O ₃ and La) with a concentration of 326g/L (calculated as RE ₂ O ₃ ) The weight ratio of ₂ O ₃ is 6:4; (RE ³⁺ is 0.9287 mol), perform metal ion exchange (temperature: 60°C, time: 1h) to obtain a metal ion exchange slurry; where RECl calculated as RE ₂ O ₃ ₃ The content of NaY molecular sieve on a dry basis is 14wt%;

(2) Add (25.6g, 0.18mol) ammonium oxalate monohydrate, and then add 5mL of 28% industrial ammonia water, so that 2.4wt% RE ³⁺ in the above metal ion exchange slurry undergoes the first precipitation (temperature is 60°C, time is 0.5h) to obtain the first precipitation slurry;

(3) Filter the above first precipitation slurry, drain it, add 1.222L ammonium sulfate aqueous solution with a concentration of 180g/L, exchange it at 100°C for 0.5h, drain it, add 5L water to rinse, and then rinse it with 100% water vapor Roast at 600°C for 2 hours in the atmosphere to obtain cross-roasted molecular sieve dry powder;

(4) After beating the above 1000 grams (dry basis weight) cross-baked molecular sieve dry powder with 5L deionized water, add (18g, 0.187 mol) ammonium carbonate to make the above-mentioned cross-baked molecular sieve dry powder 1.8wt% After the second precipitation of RE ³⁺ (temperature is 25°C, time is 0.5h), 1L ammonium sulfate aqueous solution with a concentration of 120g/L is added, Exchange at 25°C for 1 hour, filter, drain, add 4L water to rinse, and roast at 550°C for 2 hours in a 20% water vapor atmosphere to obtain modified molecular sieve Z4.

Example 5

According to the method of Example 1, the difference is that in step (1), 0.537L ( _calculated as _La2O3 ) of a LaCl ₃ solution with a concentration of 298g/L is replaced with _0.67L (calculated as _La2O3 ) concentration A LaCl ₃ solution of 298g/L, such that the content of LaCl ₃ in terms of La ₂ O ₃ in the NaY molecular sieve on a dry basis is 20wt%;

The remaining conditions were the same and modified molecular sieve Z5 was obtained.

Example 6

The method of Example 1 is followed, except that in step (2), (32 g, 0.225 mol) ammonium oxalate monohydrate is replaced with (12.8 g, 0.09 mol) ammonium oxalate monohydrate, so that 1 wt% of La ³⁺ in the above metal ion exchange slurry is subjected to a first precipitation (temperature of 80° C., time of 0.5 h);

The remaining conditions were the same and modified molecular sieve Z6 was obtained.

Example 7

The method of Example 1 is followed, except that in step (4), (25.6 g, 0.18 mol) ammonium oxalate monohydrate is replaced with (6.4 g, 0.045 mol) ammonium oxalate monohydrate, so that 0.5 wt% of La ³⁺ in the above cross-baked molecular sieve dry powder is subjected to a second precipitation (temperature of 25° C., time of 0.5 h)

The remaining conditions were the same and modified molecular sieve Z7 was obtained.

Comparative example 1

According to the method disclosed in CN200610087535.2, prepare modified molecular sieve DZ1, that is,

Take 1000 grams of NaY molecular sieve (dry basis weight), beat it with 8L of deionized water, and add 0.385L with a concentration of 312g/L (calculated as La ₂ O ₃ ) RECl ₃ solution, then add 240g aluminum sulfate, exchange at 90°C for 1 hour, then add 75g ammonium bicarbonate, stir at constant temperature for 0.25h, filter, rinse with 5L water, and then The filter cake is roasted at 600°C in a 100% water vapor atmosphere for 2 hours to obtain cross-baked molecular sieve dry powder;

Take 1000 g (dry basis weight) of the cross-baked molecular sieve powder, slurry it with 6 L of deionized water, add 300 g of ammonium sulfate, exchange it at 75° C. for 1 h, filter it, rinse it with 6 L of water, and dry the filter cake to obtain the modified molecular sieve DZ1.

Comparative Example 2

According to the method of Example 1, the difference is that in step (2), (32g, 0.225mol) ammonium oxalate monohydrate is not added, and the other conditions are the same to obtain modified molecular sieve DZ2.

Comparative example 3

According to the method of Example 2, the difference is that in step (4), (25.6g, 0.18mol) ammonium oxalate monohydrate is not added, and the other conditions are the same to obtain modified molecular sieve DZ3.

Comparative example 4

According to the method of Example 3, the difference is that in step (2), 8mL of 28% industrial ammonia water is not added, in step (4), (12.8g, 0.09mol) ammonium oxalate monohydrate is not added, and the remaining conditions are the same to obtain Modified molecular sieve DZ4.

Table 1

It can be seen from the results in Table 1 that the modified molecular sieve prepared by the method provided by the present invention has higher rare earth utilization rate, lower sulfate content and higher crystallinity.

Compared with Example 5, Example 1 adjusts the content of the soluble metal salt on a dry basis in the Na-type molecular sieve within the preferred protection range on a dry basis, and the modified molecular sieve obtained has a lower sulfuric acid content. Root content and higher crystallinity.

Compared with Example 6, Example 1 adjusts the amount of the first precipitating agent so that the content of the first precipitated metal ions is within the preferred protection range. The modified molecular sieve obtained has a lower sulfate content and a higher Crystallinity.

Compared with Example 7, Example 1 adjusts the amount of the second precipitant so that the content of precipitated metal ions is within the preferred protection range. The modified molecular sieve obtained has a lower sulfate content and a higher crystallinity. .

Test example 1

The modified molecular sieves (Z1-Z7 and DZ1-DZ4) prepared in Examples 1-7 and Comparative Examples 1-4 were subjected to hydrothermal stabilization. Qualitative testing.

The test conditions include: 100g (dry basis) modified molecular sieves (Z1-Z7 and DZ1-DZ4) are pressed into tablets, crushed into 20-40 mesh particles, and subjected to 100% water vapor and 800°C conditions in a fixed-bed hydrothermal treatment device. After aging for 10 hours, the microactivity index (MA1) was measured on the catalytic cracking automatic microreactivity evaluator. The test results are listed in Table 2.

Test Example 2

The modified molecular sieves (Z1-Z7 and DZ1-DZ4) prepared in Examples 1-7 and Comparative Examples 1-4 were tested for their resistance to heavy metal vanadium pollution.

The test conditions include: Impregnating the modified molecular sieves (Z1-Z7 and DZ1-DZ4) with equal volumes of 2000ppm ammonium metavanadate (measured in V), mixing thoroughly, leaving it sealed for 12 hours, and placed in a blast drying oven at 120°C. Dry for 16 hours, press into tablets, and grind into particles of 20-40 mesh. After aging for 2 hours at 100% water vapor and 800°C in a fixed-bed hydrothermal treatment device, measure the microactivity index on a catalytic cracking automatic microreactivity evaluator. (MA2), the test results are listed in Table 2.

Table 2

It can be seen from the data in Table 2 that compared with Comparative Examples 1-4, the modified molecular sieve prepared in Examples 1-7 has significantly higher micro-reaction activity (i.e., higher MA1 value). Therefore, the modified molecular sieve provided by the present invention has better hydrothermal stability and cracking activity.

In the same way, it can be seen from the data in Table 2 that compared with Comparative Examples 1-4, the modified molecular sieve prepared in Examples 1-7 was contaminated with 2000 ppm vanadium. After aging for 2 hours under 100% water vapor and 800°C, the micro-reaction activity was significantly higher than that of Comparative Examples 1-4. High (i.e., with a higher MA2 value). Therefore, the modified molecular sieve provided by the present invention has better resistance to heavy metal vanadium pollution.

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 concept of the present invention, many simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the disclosed content of the present invention. All belong to the protection scope of the present invention.

Claims

A method for preparing modified molecular sieves, characterized in that the preparation method includes the following steps:

(1) exchanging metal ions on a Na-type molecular sieve to obtain a metal ion slurry;

(2) adding a first precipitant to cause a portion of the metal ions in the metal ion exchange slurry to undergo a first precipitation to obtain a first precipitation slurry;

(3) the first precipitation slurry is filtered, subjected to a first ammonium sulfate exchange, subjected to a first water wash, and subjected to a first roasting in sequence to obtain a cross-exchanged and roasted molecular sieve dry powder;

(4) Add a second precipitating agent to cause a second precipitation of some metal ions in the cross-baked molecular sieve dry powder, and then sequentially perform a second ammonium sulfate exchange, a second water washing, and an optional second roasting to obtain modification Molecular sieves.
The preparation method according to claim 1, wherein in step (1), the silicon-to-aluminum ratio of the Na-type molecular sieve is 2-100;

And/or, the Na type molecule is selected from at least one of NaY molecular sieve, NaHY molecular sieve, NaUSY molecular sieve, NaREHY molecular sieve, NaREUSY molecular sieve, Naβ molecular sieve, NaHβ molecular sieve, NaREHβ molecular sieve, NaX molecular sieve, NaREX molecular sieve and NaHX molecular sieve.
The preparation method according to claim 2, wherein in step (1), the silicon-aluminum ratio of the Na-type molecular sieve is 2-50;

And/or, the Na-type molecules are selected from NaY molecular sieves and/or NaHY molecular sieves.
The preparation method according to claim 1, wherein in step (1), the metal ion exchange conditions include: temperature is 25-180°C; pH is 2.8-6.5; time is 0.3-3.5h;

And/or, the metal ion exchange process includes: mixing the Na-type molecular sieve and water, and then adding a soluble metal salt to perform the metal ion exchange.
The preparation method according to claim 4, wherein the metal ion exchange conditions include: temperature is 50-80°C; pH is 3.5-4.5; time is 0.5-1.5h;

And/or, the weight ratio of the Na-type molecular sieve and water is 1:1.5-30;

And/or, the content of the soluble metal salt calculated as oxide in the Na-type molecular sieve on a dry basis is 1-20 wt%;

And/or, the soluble metal salt is selected from chlorates and/or nitrates containing at least one element selected from rare earth elements, alkaline earth metal elements, and transition metal elements.
The preparation method according to claim 5, wherein the weight ratio of the Na-type molecular sieve and water is 1:2-5;

And/or, the content of the soluble metal salt calculated as oxide in the Na-type molecular sieve on a dry basis is 6-16 wt%.
The preparation method according to claim 1, wherein in step (2), the amount of the first precipitating agent satisfies the mole amount of the metal ions with a content of 1-4wt% in the Na-type molecular sieve after the first precipitation. proportion;

And/or, the first precipitating agent is selected from at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate, ammonia, urea and ammonium acetate;

And/or, the conditions for the first precipitation include: temperature is 25-180°C; time is 0.1-5h.
The preparation method according to claim 7, wherein in step (2), the amount of the first precipitating agent satisfies the concentration of 1.5-2.5 wt% of metal ions in the Na-type molecular sieve after the first precipitation. molar ratio;

And/or, the first precipitating agent is selected from at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate and ammonia water;

And/or, the conditions for the first precipitation include: temperature is 50-80°C; time is 0.1-2h.
The preparation method according to claim 1, wherein in step (3), the first ammonium sulfate exchange process includes: exchanging the filtered product and the first ammonium sulfate aqueous solution;

And/or, the conditions for the first ammonium sulfate exchange include: temperature is 15-150°C; time is 0.1-5h;

And/or, the amount of water used in the first water washing is 1-8 times the weight of the Na-type molecular sieve;

And/or, the conditions for the first roasting include: 100% water vapor atmosphere; temperature 400-700°C; time 0.1-5h.
The preparation method according to claim 9, wherein the weight ratio of the first ammonium sulfate aqueous solution and Na-type molecular sieve calculated as ammonium sulfate is 5-50:100;

And/or, the concentration of ammonium sulfate in the first ammonium sulfate aqueous solution is 20-400g/L;

And/or, the conditions for the first ammonium sulfate exchange include: temperature is 50-80°C; time is 0.5-2h;

And/or, the amount of water used in the first water washing is 2-5 times the weight of the Na-type molecular sieve;

And/or, the conditions for the first roasting include: temperature is 500-650°C; time is 0.5-3h.
The preparation method according to claim 10, wherein the weight ratio of the first ammonium sulfate aqueous solution and Na-type molecular sieve calculated as ammonium sulfate is 10-25:100;

And/or, the concentration of ammonium sulfate in the first ammonium sulfate aqueous solution is 120-250g/L.
The preparation method according to claim 1, wherein in step (4), the amount of the second precipitant is such that the content of the metal ions in the cross-baked molecular sieve dry powder is 0.5-3wt% through the second precipitant. The molar ratio of precipitation;

And/or, the second precipitating agent is selected from ammonium oxalate, ammonium carbonate, ammonium bicarbonate, ammonia, urea and ammonium acetate at least one of;

And/or, the conditions for the second precipitation include: temperature is 15-40°C; time is 0.1-5h;

And/or, the second ammonium sulfate exchange process includes: exchanging the second precipitation product and the second ammonium sulfate aqueous solution;

And/or, the conditions for the second ammonium sulfate exchange include: temperature is 20-85°C; time is 0.1-5h;

And/or, the amount of water used in the second water washing is 1-8 times the weight of the cross-baked molecular sieve dry powder;

And/or, the conditions for the second roasting include: 20-100% water vapor atmosphere; temperature 400-700°C; time 0.1-10h.
The preparation method according to claim 12, wherein the amount of the second precipitating agent satisfies the molar ratio of the second precipitation of metal ions with a content of 1-2wt% in the cross-baked molecular sieve dry powder;

And/or, the second precipitating agent is selected from at least one of ammonium oxalate, ammonium carbonate, ammonium bicarbonate and ammonia water;

And/or, the conditions for the second precipitation include: temperature is 20-30°C; time is 0.1-2h.

And/or, the weight ratio of the second ammonium sulfate aqueous solution and cross-baked molecular sieve dry powder calculated as ammonium sulfate is 5-50:100;

And/or, the concentration of ammonium sulfate in the second ammonium sulfate aqueous solution is 20-400g/L;

And/or, the conditions for the second ammonium sulfate exchange include: temperature is 50-80°C; time is 0.1-2h;

And/or, the amount of water used in the second water washing is 2-5 times the weight of the cross-baked molecular sieve dry powder;

And/or, the conditions for the second roasting include: temperature is 450-650°C; time is 0.5-5h.
The preparation method according to claim 13, wherein the weight ratio of the second ammonium sulfate aqueous solution and the cross-baked molecular sieve dry powder calculated as ammonium sulfate is 10-25:100;

And/or, the concentration of ammonium sulfate in the second ammonium sulfate aqueous solution is 120-250g/L.
The preparation method according to any one of claims 1-14, wherein before the second precipitation, the cross-baked molecular sieve dry powder and water are mixed;

Wherein, the weight ratio of the cross-baked molecular sieve dry powder and water is 1:1.5-30.
The modified molecular sieve prepared by the preparation method according to any one of claims 1-15;

Wherein, the SO 4 2- content in the modified molecular sieve is ≤0.5wt%.
The modified molecular sieve according to claim 16, wherein the SO 4 2- content in the modified molecular sieve is 0.01-0.45wt%.
Application of the modified molecular sieve described in claim 16 or 17 in heavy oil conversion and resistance to heavy metal vanadium pollution.