CN112808298B

CN112808298B - Catalyst containing hierarchical pore Y-type molecular sieve and preparation method thereof

Info

Publication number: CN112808298B
Application number: CN201911126333.8A
Authority: CN
Inventors: 付强; 李永祥; 张成喜; 王子建; 胡合新
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2019-11-18
Filing date: 2019-11-18
Publication date: 2023-07-11
Anticipated expiration: 2039-11-18
Also published as: CN112808298A

Abstract

The invention provides a preparation method of a catalyst containing a hierarchical pore Y-type molecular sieve, which is characterized by comprising the steps of contacting the Y-type molecular sieve with an acidic solution containing hydrogen ions and at least two different carboxylate ions, regulating the pH value to be 4.5-5.5, filtering, washing and drying to obtain the hierarchical pore Y-type molecular sieve, and then mixing the hierarchical pore Y-type molecular sieve with a matrix material.

Description

Catalyst containing hierarchical pore Y-type molecular sieve and preparation method thereof

Technical Field

The invention relates to a catalyst containing a Y-type molecular sieve and a preparation method thereof, and further relates to a catalyst containing a hierarchical pore Y-type molecular sieve and a preparation method thereof.

Background

At the end of fifty years, milton and Breck successfully synthesized Y-type molecular sieves due to SiO in the structure of NaY molecular sieves ₂ /Al ₂ O ₃ The ratio is larger than that of the X-type molecular sieve, so that the thermal stability and the water stability are improved. In the beginning of seventies, grace developed a guiding agent method for synthesizing NaY molecular sieves, and water glass was used as a raw material to replace expensive silica sol, so that the process is simplified, and the growth cycle is shortened, thereby enabling the NaY molecular sieves to be rapidly and widely applied to petrochemical industry, particularly the petroleum cracking catalytic field. Among the hundreds of molecular sieves that have been developed so far, the largest amount used in industry is the Y-type molecular sieve. Currently, the synthesis of NaY molecular sieves is mainly carried out industrially by a seed crystal gel method. The use and improvement of the seed crystal gel greatly shortens the synthesis crystallization time of the Y-type molecular sieve and lays a foundation for the industrialization of the Y-type molecular sieve. The application and development of industry put higher demands on the synthesis of molecular sieves and the performance of the products thereof, which in turn promotes the intensive research of the synthesis of molecular sieves, and the synthesis of Y-type molecular sieves with hierarchical pores and regular mesopores becomes a new hot spot.

Preparing a hierarchical pore structure molecular sieve is yet another solution. In designing a catalyst, it is desirable to maximize the accessibility of the active sites to fully exploit its catalytic potential, and to minimize the pore space to achieve higher catalytic activity. There is therefore a need to find an optimal balance between the accessibility of the active sites and the bulk density of the active sites, i.e. to create an optimal hierarchical pore distribution in the catalytic material. The hierarchical pore molecular sieve truly realizes the functions of hierarchical pore structure, namely hierarchical pore distribution and hierarchical acid strength distribution.

The presently reported methods for preparing hierarchical pore molecular sieves can be largely categorized into "constructive" and "destructive" methods. "constructive" methods are also known as template methods, and are classified into hard template methods and soft template methods according to template types. The pore volume and the pore diameter of the hierarchical pore structure zeolite synthesized by using the hard template are totally dependent on the particle size and the dispersity of the hard template because the hard template and the molecular sieve synthesis raw material have no direct effect because the pore volume of the medium pore is larger and the pore distribution is wider. The pore volume of the hierarchical zeolite mesoporous structure synthesized by using the soft template is smaller than that of the sample synthesized by using the hard template, and is generally concentrated in 0.2-0.5 cm ³ And the mesoporous distribution is narrower between/g. The common soft template mainly comprises high molecular polymer, organosilane, surfactant and the like, and the cost for synthesizing the sample by using the soft template is high. The destructive method is mainly divided into dealumination modification and desilication modification. Typical dealumination processes include hydrothermal dealumination and acid treatment dealumination. Dealumination modification can generate a large number of secondary mesoporous defects in the molecular sieve framework. For the silicon-aluminum molecular sieve with low silicon-aluminum ratio, the dealumination treatment is a simple and easy method for forming the intra-crystal mesopores. For the Y-type molecular sieve, the most widely used method for preparing the hierarchical pores in industry at present is to prepare the mesopores by a hydrothermal treatment method, and the method has the advantages of easy operability and low industrial amplification cost, but similar to other dealumination modification, closed mesopore cavities are inevitably introduced. Therefore, the modification method has no obvious advantage for improving the mass transfer performance of the molecular sieve.

In the synthesis of a multi-stage pore canal zeolite molecular sieve, another research hot spot is to utilize organosilane to regulate crystallization of the zeolite molecular sieve, and long-chain alkylsilane coupling agent is adopted to limit growth of the zeolite molecular sieve and synthesize nano zeolite. The zeolite molecular sieve with disordered mesoporous channels in the crystal can be successfully synthesized by adopting the partially silanized polymer as a template. In 2006, serrano et al found that organosilane can limit zeolite molecular sieve growth, and during zeolite synthesis organosilane forms with conventional silica alumina species a multi-stage pore zeolite molecular sieve that is stable under hydrothermal conditions (Serrano D.P., aguado J., escola J.M., rodriguez J.M., peral A.: hierarchical Zeolites with Enhanced Textural and Catalytic Properties Synthesized from Organofunctionalized Seeds [ J ]. Chem. Mater.,2006, 18:2462-2464.). The organosilane can limit the growth of zeolite molecular sieves, and can form multistage pore channels with conventional silicon aluminum species under hydrothermal conditions during the synthesis of zeolite. The method utilizes organosilane to be added into the pre-crystallized zeolite molecular sieve synthetic gel to synthesize Si-C bonds of the zeolite molecular sieve with disordered mesoporous channels in crystals, and limits the growth of the zeolite molecular sieve, thereby obtaining the agglomeration of the nano zeolite molecular sieve. The nano zeolite agglomerates have a very small particle size and a large number of mesopores are present. CN102774854a discloses a synthesis method of a meso-microporous NaY molecular sieve, which uses a reaction product substituted by NH group polymer and aliphatic epoxy silane amine as a template agent, and adds the template agent in the process of synthesizing the Y molecular sieve to generate a meso-microporous structure in situ.

CN102936017B discloses a mesoporous nano zeolite aggregate and a preparation method thereof. The method comprises the steps of silanizing the surface of nano silicon dioxide, adding a template agent and an aluminum source by taking the silicon source as a silicon source, and carrying out hydrothermal crystallization under certain conditions to obtain Beta nano zeolite aggregates formed by self-aggregation of nano zeolite crystal grains with inner crystal mesopores. Overcomes the defect that nano Beta zeolite is not easy to separate in the synthesis and use processes.

CN102874836a discloses a method for synthesizing mesoporous a-type molecular sieve. The method adopts a mixture of multi-wall carbon nanotubes and silane coupling agents after bridging as a template agent, adds another silane coupling agent after adding the mixture into a silicon source, processes the mixture under the heating condition to react, transfers the mixture into an aluminum source after finishing the reaction, and removes the template agent through high-temperature calcination after stirring, crystallization, suction filtration, washing and drying, thus obtaining the mesoporous A-type molecular sieve.

US20070258884 reports the modification of polyethyleneimine with 3- (2, 3-glycidoxy) propyltrimethoxysilane to prepare a mixed template agent, in-situ generation of mesopores in the synthesis process of ZSM-5 molecular sieves, the pore size of the mesopores being concentrated around 3 nm.

The patent adopts the template agent added in the synthesis process of the molecular sieve to prepare micropores and mesopores in situ. When the catalyst is used in the hydrothermal synthesis of the Y molecular sieve, P-type hetero-crystals are easy to generate, the synthesis of the Y molecular sieve is influenced, and further the generation of micropores and mesopores is influenced.

Disclosure of Invention

The invention aims to provide a preparation method of a catalyst containing a hierarchical pore Y-type molecular sieve and a catalyst obtained by the method, aiming at the problems of low crystallinity and low strength of B acid existing in the existing catalyst after two steps of dealumination and desilication of an active component Y-type molecular sieve.

The preparation process of the catalyst with hierarchical porous Y-type molecular sieve includes contacting the Y-type molecular sieve with acid solution containing hydrogen ion and at least two kinds of different carboxylate radical ion, regulating pH value to 4.5-5.5, filtering, washing and drying to obtain the hierarchical porous Y-type molecular sieve, and mixing with matrix material.

The invention also provides a catalyst containing the hierarchical pore Y-type molecular sieve, which is obtained by the preparation method.

The preparation method of the invention adopts special treatment steps, has obvious protection effect on the crystallinity of the molecular sieve, and only involves dealumination in the process, thereby avoiding the damage of the removal of framework silicon to strong B acid.

Drawings

FIG. 1 is a TEM photograph of a hierarchical pore-containing Y-type molecular sieve sample A obtained in example 1.

FIG. 2 is a TEM photograph of a hierarchical pore-containing Y-type molecular sieve sample B obtained in example 2.

FIG. 3 is a TEM photograph of a hierarchical pore-containing Y-type molecular sieve sample C obtained in example 3.

FIG. 4 shows mesoporous pore size distribution curves of samples A and C containing the hierarchical pore Y-type molecular sieve obtained in examples 1 and 3, respectively.

Detailed Description

In the preparation method, the Y-type molecular sieve containing the hierarchical pores is obtained by contacting the Y-type molecular sieve with an acidic solution, regulating the pH value to be 4.5-5.5, and filtering, washing and drying, wherein the acidic solution contains hydrogen ions and at least two different carboxylate ions. The method comprises the steps of adjusting the pH value, and the dealumination rate and the aluminum supplementing rate of the molecular sieve in the acidic solution by controlling the type and the concentration of carboxylate ions in the acidic solution. When the dealumination rate is greater than the aluminum supplementing rate to a certain extent, mesopores can be introduced into the molecular sieve. When the dealumination rate is approximately equal to or far greater than the aluminum replenishment rate, no mesopores can be formed. Different carboxylate ions have different capabilities to promote dealumination or make-up aluminum.

The ratio of the acid solution to the Y-type molecular sieve is 8-25:1, wherein the acidic solution is in volume (mL) and the Y-type molecular sieve is in mass (g).

The carboxylate ions are at least two selected from oxalate ions, lactate ions and citrate ions. The concentration of the carboxylate ions is 0.1-0.5 mol/L. The carboxylate ions are preferably oxalate ions and lactate ions. The proportion of oxalate ions to lactate ions is 0.4-2.5 based on carboxylate ions mole: 1

In the process of contacting the Y-type molecular sieve with the acidic solution, the acidic solution can be prepared by mixing one carboxylic acid with the ammonium salt of the other carboxylic acid, or can be prepared by preparing a mixed acid solution from the two carboxylic acids, and then dropwise adding ammonia water to adjust the pH value to 4.5-5.5. In the process of contacting the Y-type molecular sieve with the acidic solution, the temperature is 20-100 ℃, preferably 80-100 ℃ for 1-12 hours, preferably 2-4 hours.

In the preparation method of the invention, the Y-type molecular sieve can be NaY or NH ₄ Y molecular sieves, preferably NH ₄ And Y molecular sieve.

More preferred Y-type molecular sieves should have a uniform aluminum distribution. The acid treatment chemical dealumination method is an outside-in dealumination method, so that dealumination is uneven, namely the dealumination degree of the outer surface of the molecular sieve is maximum, and dealumination degree in the molecular sieve is smaller, so that uneven distribution of acid sites in and out of the molecular sieve is caused, more acid sites in the molecular sieve with lower accessibility and less acid sites on the outer surface layer with higher accessibility are caused, and the catalytic effect of the Y molecular sieve is inevitably influenced by the acid distribution. In order to solve the problem of uneven dealumination existing in the chemical dealumination method under the common acid treatment, the more preferable Y-type molecular sieve is prepared by the following steps: NH (NH) ₄ The Y molecular sieve is contacted with a salt solution containing alkali metal ions and/or a salt solution containing alkaline earth metal ions, and the product is obtained after filtering, washing and drying, wherein the alkali metal is selected from rubidium and cesium, and the alkaline earth metal is selected from strontium and barium. Wherein the salt solution containing alkali metal ions is selected from rubidium chloride, cesium chloride, rubidium nitrate, cesium nitrate, rubidium sulfate and cesium sulfate, and the salt solution containing alkaline earth metal ions is selected from strontium chloride, barium chloride and strontium nitrate. The concentration of the salt solution containing alkali metal ions or the salt solution containing alkaline earth metal ions is 0.1-2 mol/L. Preferably, the alkali metal is cesium or rubidium, and the concentration of the alkali metal ion solution is 0.5-1 mol/L of NH ₄ The Y molecular sieve is contacted with the salt solution containing alkali metal ions and/or the salt solution containing alkaline earth metal ions for 0.2 to 2 hours at the temperature of 20 to 80 ℃.

In the preparation method of the invention, the matrix material is selected from one or more of alumina, silica and clay. Precursors of alumina are, for example, hydrated alumina, alumina sol. The hydrated alumina is selected from one or more of hydrated aluminas commonly used in cracking catalysts, such as one or more of hydrated aluminas having pseudo-Boehmite structure (pseudoboehmite), boehmite (Boehmite), gibbsite (Gibbsite) and Bayerite (Bayerite) structures, preferably pseudo-Boehmite and/or Gibbsite. The precursor of the silicon oxide is silica sol. The Y-type molecular sieve containing the hierarchical pores is mixed with a matrix material to form slurry with the solid content of 35-40%. The acid is selected from hydrochloric acid, nitric acid or phosphoric acid. In a preferred embodiment, the hierarchical pore-containing Y-type molecular sieve is mixed with the matrix material, the components are added in the sequence of adding acid into pseudo-boehmite, then adding clay, uniformly mixing, then adding the hierarchical pore-containing Y-type molecular sieve, and finally adding alumina sol, silica sol and water. In the addition sequence described in the preferred embodiment, the clay is partially peptized under the action of pseudo-boehmite and acid, and after the molecular sieve is added, the carrier and the molecular sieve are bonded, so that the strength of the catalyst can be improved, and finally, the alumina sol and the silica sol are added, so that the molecular sieve and the carrier are ensured to be mixed uniformly to the greatest extent.

The invention also provides the catalyst containing the hierarchical pore Y-type molecular sieve, which is prepared by the preparation method, and the micropore specific surface area of the catalyst is 400-650 m ² Per gram, the micropore volume is 0.25-0.35 cm ³ Per gram, the specific surface area of the mesoporous is 30 to 200m ² Per g, mesoporous volume of 0.07-0.85 cm ³ And/g, the mesoporous aperture is 2.0-6.0 nm, and the intensity is 8.5-13.5N/mm.

The invention is further illustrated by the following examples, which are not intended to limit the scope of the invention.

In the examples and comparative examples, the relative crystallinity of the molecular sieves was determined by X-ray diffraction (XRD). The experimental instrument is an XPert Powder X-ray diffractometer of the Panatt company of Netherlands. The testing process comprises the following steps: tube voltage 40kV, tube current 40ma, cu target ka radiation, scan speed 2 (°/min, scan range 2θ=5° to 35 °. The (5,3,3) crystal face peak area was used to calculate the relative crystallinity of the molecular sieve.

In the examples and comparative examples, the pore structure parameters of the molecular sieves were determined by the low temperature nitrogen adsorption capacity method (BET). The experimental instrument was an ASAP24000 adsorber from micromrtitics company, USA. The testing process comprises the following steps: degassing the sample at 300 ℃ for 6 hours, performing nitrogen adsorption and desorption test at 77.4K to obtain a nitrogen adsorption-desorption curve, calculating the specific surface area of the sample by using a BET formula, and calculating the mesoporous pore size distribution by using a BJH method.

In the examples and comparative examples, the mesoporous morphology of the molecular sieves was observed by Transmission Electron Microscopy (TEM). The experimental instrument was an F20G 2 transmission electron microscope from FEI.

In examples and comparative examples, the acid amount of the molecular sieve was determined from NH ₃ And (3) measuring temperature programmed desorption (NH 3-TPD). The experimental instrument is Autochem II 2920 temperature programming desorption instrument of America microphone company. The testing process comprises the following steps: weighing 0.15g of molecular sieve powder, placing the molecular sieve powder in a sample tube, placing the sample tube in a heating furnace of a thermal conductivity cell, taking helium as carrier gas (25 mL/min), heating to 550 ℃ at a speed of 20 ℃/min, and purging for 60min to remove impurities adsorbed on the surface of the molecular sieve. Then cooling to 100 ℃, keeping the temperature for 10min, switching ammonia helium mixed gas (10.02 percent of NH3+89.98 percent of He) for adsorption for 30min, and continuing to purge with helium for 90min until the baseline is stable, so as to desorb the physically adsorbed NH3. Heating to 250 ℃ at a speed of 10 ℃/min, maintaining for 30min, heating to 350 ℃ at a speed of 10 ℃/min, maintaining for 30min, heating to 450 ℃ at a speed of 10 ℃/min, maintaining for 30min, heating to 550 ℃ at a speed of 10 ℃/min, and maintaining for 30 min. And detecting the change of the gas components by adopting a TCD detector, and automatically integrating by an instrument to obtain the acid quantity at each temperature.

In the examples and comparative examples, the B acid acidity of the molecular sieves was determined by pyridine adsorption infrared spectroscopy (Py-FTIR). The experimental instrument is a model TENSOR II infrared spectrometer of Bruker company. The testing process comprises the following steps: about 20mg of molecular sieve is taken and pressed into a tablet, the tablet is placed in an in-situ tank of an infrared spectrometer for sealing, the temperature is raised to 500 ℃ at the speed of 10 ℃/min, and the vacuum pumping treatment is carried out for 2 hours, so as to desorb impurities such as water molecules physically adsorbed by the molecular sieve. After cooling to room temperature, a background spectrum was collected, and pyridine was adsorbed for 10min. Then heating to 200 ℃ at a speed of 10 ℃/min, vacuumizing for 30min, cooling to room temperature, measuring pyridine adsorption infrared spectrum, and calculating total acid content by integration; then heating to 350 ℃, vacuumizing for 30min, cooling to room temperature, measuring pyridine adsorption infrared spectrum, and integrating to calculate the strong acid amount.

In examples and comparative examples, the catalyst strength was measured by tabletting and pulverizing the catalyst into 20 to 40 mesh particles and measuring the particles on a DL 3-type particle strength measuring instrument manufactured by the technology of Lian Peng.

The starting materials used in the examples were all analytically pure reagents unless otherwise specified.

Example 1

This example illustrates the process of dealuminating a Y-type molecular sieve with lactic acid/ammonium oxalate to obtain a Y-type molecular sieve with hierarchical pores.

An acidic solution containing lactate and oxalate was prepared by mixing 3.60g of lactic acid (national drug Cluster chemical reagent Co., ltd., hereinafter referred to as "C"), 5.68g of ammonium oxalate monohydrate (national drug Cluster chemical reagent Co., hereinafter referred to as "C.) and adding water to 200 mL. Wherein the concentration of lactate and oxalate ions is 0.2mol/L.

10g NaY molecular sieve (supplied by Kagaku catalyst Co., ltd., n (Si)/n (Al) =2.5, na) ₂ O% = 13%, the following is the same) according to a general method (NaY molecular sieve and 120g/L ammonium chloride solution are mixed and beaten, the solid-liquid ratio is 1:3.75, the mixture is heated to 85 ℃ for 1h, and suction filtration is carried out; repeating the above steps for 1 time, filtering, washing, adding distilled water into a filter cake for pulping, adjusting the pH value to 8.0-8.5 by using dilute ammonia water, filtering, and drying; the obtained sample is roasted for 2 hours at 550 ℃, the ammonium exchange step is repeated for 4 times, and the obtained sample is subjected to suction filtration, washing and drying. ) Ammonium exchange to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ Adding the Y molecular sieve into the 200mL of acid solution, heating to 100 ℃, adjusting the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying to obtain the product A.

The relative crystallinity and pore structure parameters of sample A are shown in Table 1, the acid data are shown in Table 2, the bulk phase and surface composition characterization of the molecular sieve are shown in Table 3, the morphology of sample A is shown in TEM photograph shown in FIG. 1, and the mesoporous pore size distribution is shown in FIG. 4.

Comparative example 1

Description of the present comparative example pair NH ₄ The Y molecular sieve was subjected to a 0.2mol/L lactic acid treatment and the comparative sample obtained.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve is added into 200mL of 0.2mol/L lactic acid solution, heated to 100 ℃ for 2h, filtered, washed and dried, and the obtained product is marked as DB1.

The comparative sample DB1 has the relative crystallinity and pore structure parameters shown in Table 1, the acid data shown in Table 2, and the bulk and surface composition characterization of the molecular sieves shown in Table 3.

Comparative example 2

Description of the present comparative example pair NH ₄ The Y molecular sieve was subjected to a 0.2mol/L oxalic acid treatment and the comparative sample obtained.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve is added into 200mL of 0.2mol/L oxalic acid solution, heated to 100 ℃ for 2h, filtered, washed and dried, and the obtained product is marked as DB2.

The comparative sample DB2 has the relative crystallinity and pore structure parameters shown in table 1, the acid data shown in table 2, and the bulk and surface composition characterization of the molecular sieve shown in table 3.

Comparative example 3

Description of the present comparative example pair NH ₄ The Y molecular sieve was subjected to only the procedure of lactic acid/oxalic acid mixed acid treatment and the comparative sample obtained.

A mixed acid solution of lactic acid and oxalic acid was prepared by mixing 3.60g of lactic acid (molecular weight 90.08) and 5.04g of oxalic acid dihydrate (national pharmaceutical chemicals, the same applies below) and adding water to 200 mL. Wherein the concentration of lactic acid and oxalic acid is 0.2mol/L.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ Adding the Y molecular sieve into the mixed acid solution, heating to 100 ℃ for 2 hours, filtering, washing and drying to obtain a product which is named DB3.

The comparative sample DB3 has the relative crystallinity and pore structure parameters shown in table 1, the acid data shown in table 2, and the bulk and surface composition characterization of the molecular sieve shown in table 3.

Example 2

This example illustrates the process of dealuminating a Y-molecular sieve with lactic acid/ammonium oxalate to obtain a Y-molecular sieve containing hierarchical pores.

An acidic solution containing lactate and oxalate was prepared by mixing 3.60g of lactic acid and 5.68g of ammonium oxalate monohydrate and adding water to 200 mL. Wherein the concentration of lactate and oxalate ions is 0.2mol/L.

10g of NaY molecular sieve is added into the 200mL of acid solution, heated to 100 ℃, the pH value of the solution is regulated to 4.5-5.5, the solution is treated for 2 hours, and the obtained product is marked as B after filtration, washing and drying.

The relative crystallinity and pore structure parameters of sample B are shown in table 1, the acid data are shown in table 2, and the bulk and surface composition characterization of the molecular sieve are shown in table 3. The morphology of the sample B is shown in a TEM picture shown in figure 2.

Example 3

3.60g of lactic acid and 11.37g of ammonium oxalate monohydrate are taken and mixed, and water is added to 200mL to prepare an acidic solution containing lactate and oxalate, wherein the concentration of lactate ions is 0.2mol/L and the concentration of oxalate ions is 0.4mol/L.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ Adding the Y molecular sieve into the 200mL of acid solution, heating to 100 ℃, adjusting the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying to obtain the product C.

The relative crystallinity and pore structure parameters of sample C are shown in Table 1, the acid data are shown in Table 2, and the bulk and surface composition characterization are shown in Table 3. The morphology of the sample C is shown in a TEM photograph shown in fig. 3, and the mesoporous pore size distribution is shown in fig. 4.

Comparative example 4

The comparative example provides NH obtained by directly subjecting NaY molecular sieves to ammonium exchange ₄ A sample of Y molecular sieve, designated DB4, was used to compare the B acid strength of the sample obtained by the method of the invention, DB 4.

The comparative sample DB4 has the relative crystallinity and pore structure parameters shown in table 1 and the acid data shown in table 2. The bulk and surface composition characterization of the molecular sieves is shown in Table 3

Example 4

This example illustrates the process of performing oxalic acid/citric acid dealumination on a Y-molecular sieve to obtain a hierarchical pore-containing Y-molecular sieve.

Ammonium exchanging 10g NaY molecular sieve according to general method to obtain NH ₄ And mixing 10.08g of oxalic acid dihydrate and 16.81g of citric acid monohydrate, and adding water to 200mL to obtain an oxalic acid/citric acid mixed acid solution, wherein the concentration of oxalate ions and citrate ions is 0.2mol/L. Heating the mixed acid solution to 80 ℃, dropwise adding ammonia water at the temperature until the pH value of the solution is 4.5-5.5, and adding NH ₄ Adding Y molecular sieve into the solution, treating at 80 ℃ for 4 hours, filtering, washing and drying to obtain the product D.

The relative crystallinity and pore structure parameters for sample D are shown in Table 1, and the acid data are shown in Table 2. The bulk and surface composition characterization of the molecular sieves is shown in table 3.

Sample D shows similar characteristics to sample A, namely mesoporous appears, the relative crystallinity is higher, and the acid quantity and the acid strength of B are slightly increased, but the mesoporous pore diameter is uneven.

Example 5

This example illustrates the process of subjecting a Y-type molecular sieve to cesium ion exchange and lactic acid/ammonium oxalate dealumination to obtain a Y-type molecular sieve containing hierarchical pores.

10g NaY molecular sieve (supplied by Kagaku catalyst Co., ltd., n (Si)/n (Al) =2.5, na) ₂ O% = 13%, the following is the same) according to a general method (NaY molecular sieve and 120g/L ammonium chloride solution are mixed and beaten, the solid-liquid ratio is 1:3.75, the mixture is heated to 85 ℃ for 1h, and suction filtration is carried out; repeating the above steps for 1 time, filtering, washing, adding distilled water into a filter cake for pulping, adjusting the pH value to 8.0-8.5 by using dilute ammonia water, filtering, and drying; the obtained sample is roasted for 2 hours at 550 ℃, the ammonium exchange step is repeated for 4 times, and the obtained sample is subjected to suction filtration, washing and drying. ) Ammonium exchange to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve was added to 40mL of distilled water, stirred and beaten at 30℃and 3.37g of cesium chloride (Aba Ding Shiji (Shanghai) Co., ltd.) was added thereto, and the mixture was exchanged for 0.5 hours, filtered, washed and dried to obtain a cesium ion exchanged product.

An acidic solution containing lactate and oxalate was prepared by mixing 3.60g of lactic acid (national drug Cluster chemical reagent Co., ltd., hereinafter referred to as "C"), 5.68g of ammonium oxalate monohydrate (national drug Cluster chemical reagent Co., hereinafter referred to as "C.) and adding water to 200 mL.

Adding the cesium ion exchange product into 200mL of the acid solution, heating to 100 ℃, adjusting the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying, and carrying out ammonium exchange on the obtained sample for 4-6 times, wherein the obtained product is marked as E.

The relative crystallinity and pore structure parameters of sample E are shown in Table 1, the acid data are shown in Table 2, and the bulk and surface composition characterization are shown in Table 3.

The molecular sieve morphology of sample E is similar to sample A, and a large number of relatively uniform mesopores appear.

Comparative example 5

This comparative example illustrates the sodium ion exchange and lactic acid/ammonium oxalate dealumination of a Y molecular sieve.

An acidic solution containing lactate and oxalate was prepared by mixing 3.60g of lactic acid and 5.68g of ammonium oxalate monohydrate and adding water to 200 mL.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve was added to 40mL of distilled water, stirred and beaten at 30℃and then 2.34g of sodium chloride (Ala Ding Shiji (Shanghai) Co., ltd.) was added thereto, and the mixture was exchanged for 0.5h, filtered, washed and dried to obtain a sodium ion exchanged sample. Adding the obtained sample into the acidic solution, heating to 100 ℃, adjusting the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying, and then carrying out ammonium exchange on the obtained sample for 4-6 times, wherein the obtained product is DB5. This comparative sample DB5 was used for comparison with the E sample described above, demonstrating Cs ⁺ With Na and Na ⁺ Different roles in the process.

The comparative sample DB5 has the relative crystallinity and pore structure parameters shown in Table 1, the acid data shown in Table 2, and the bulk and surface composition characterization shown in Table 3.

Example 6

This example illustrates the process of subjecting a Y-molecular sieve to rubidium ion exchange and lactic acid/ammonium oxalate dealumination to obtain a hierarchical pore-containing Y-molecular sieve.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ Adding the Y molecular sieve into 40mL of distilled water, stirring and pulping at 80 ℃, adding 9.68g of rubidium chloride (Ara Ding Shiji (Shanghai) Co., ltd.), exchanging for 2h, filtering, washing and drying to obtain rubidium ion exchanged product.

Adding the obtained rubidium ion exchange product into the acid solution, heating to 100 ℃, adjusting the pH value of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying the obtained sample, and carrying out ammonium exchange for 4-6 times, wherein the obtained product is marked as F.

The relative crystallinity and pore structure parameters of sample F are shown in Table 1, the acid data are shown in Table 2, and the bulk and surface composition characterization are shown in Table 3.

Example 7

This example illustrates the process of subjecting a Y-type molecular sieve to strontium ion exchange and lactic acid/ammonium oxalate dealumination to obtain a Y-type molecular sieve containing hierarchical pores.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve was added to 40mL of distilled water, stirred and beaten at 20℃and 6.34g of strontium chloride (Ara Ding Shiji (Shanghai) Co., ltd.) was added thereto, and the resultant was exchanged for 1 hour, filtered, washed and dried.

An acidic solution containing lactate and oxalate was prepared by mixing 3.60g of lactic acid and 11.37g of ammonium oxalate monohydrate and adding water to 200 mL.

Adding the strontium ion exchanged product into the 200mL of acid solution, heating to 100 ℃, adjusting the pH value of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying the obtained sample, and carrying out ammonium exchange for 4-6 times, wherein the obtained product is marked as G.

The relative crystallinity and pore structure parameters of sample G are shown in table 1, the acid data are shown in table 2, and the bulk and surface composition characterization are shown in table 3.

Example 8

This example illustrates the process of subjecting a Y-molecular sieve to barium ion exchange and lactic acid/ammonium oxalate dealumination to obtain a Y-molecular sieve containing hierarchical pores.

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ Adding the Y molecular sieve into 40mL of distilled water, stirring and pulping at 20 ℃, adding 2.50g of barium chloride (Ala Ding Shiji (Shanghai) Co., ltd.) into the mixture, exchanging for 1h, filtering, washing and drying to obtain a barium ion exchanged product.

Adding the barium ion exchanged product into 200mL of the acid solution containing lactate and oxalate, heating to 100 ℃, adjusting the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying, and carrying out ammonium exchange on the obtained sample for 4-6 times, wherein the obtained product is named as H.

The relative crystallinity and pore structure parameters of sample H are shown in Table 1, the acid data are shown in Table 2, and the bulk and surface composition characterization are shown in Table 3.

Example 9

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve was added to 40mL of distilled water, stirred and beaten at 80℃and 6.74g of cesium chloride (Aba Ding Shiji (Shanghai) Co., ltd.) was added thereto, and the mixture was exchanged for 0.5 hours, filtered, washed and dried to obtain a cesium ion exchanged product.

Adding cesium ion exchange product into the 200mL acid solution containing lactate and oxalate, heating to 100 ℃, regulating the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying, and carrying out ammonium exchange on the obtained sample for 4-6 times, wherein the obtained product is named as I.

The relative crystallinity and pore structure parameters of sample I are shown in Table 1, the acid data are shown in Table 2, and the bulk and surface composition characterization are shown in Table 3.

Example 10

Ammonium exchange is carried out on 10g NaY molecular sieve according to a general method to obtain NH ₄ And Y molecular sieve. The NH obtained ₄ The Y molecular sieve was added to 40mL of distilled water, stirred and beaten at 30℃and then 1.69g of cesium chloride (Aba Ding Shiji (Shanghai) Co., ltd.) was added thereto, and the mixture was exchanged for 2 hours, filtered, washed and dried to obtain a cesium ion exchanged product.

Heating 200mL of the acidic solution containing lactate and oxalate to 100 ℃, regulating the pH of the solution to 4.5-5.5, treating for 2 hours, filtering, washing and drying, and then carrying out ammonium exchange on the obtained sample for 4-6 times, wherein the obtained product is named J.

The relative crystallinity and pore structure parameters of sample J are shown in Table 1, the acid data are shown in Table 2, and the bulk and surface composition characterization are shown in Table 3.

TABLE 1

TABLE 2

As can be seen from Table 1 and FIG. 1, a large number of mesopores appeared in sample A, while no mesopores were generated in samples DB1, DB2, and DB3. This suggests that either a single lactic acid, oxalic acid treatment, or a simple mixing of both treatments cannot be performed in NH ₄ The mesoporous particles were introduced into the Y molecular sieve, as in example 1When the acid solution contains two acid radical ions and has pH of 4.5-5.5, the acid solution can be treated in NH ₄ Mesoporous is introduced into the Y molecular sieve, and the crystallinity is kept high.

As shown in Table 1 and FIG. 2, a larger number of mesopores were also present in sample B, but the mesopore area and volume were slightly smaller than that of sample A, indicating that the treatment was equally effective on NaY molecular sieves, except that the mesopore introducing effect was slightly worse than that of NH ₄ And Y molecular sieve.

In example 3, compared with example 1, the amount of oxalate ions is increased, and as shown in table 1, fig. 3 and fig. 4, the mesoporous pores of the sample C obtained after the oxalate ions are increased are also increased, but the mesoporous pore diameter is obviously increased compared with that of the sample a, and the degree of mesoporous non-uniformity is also increased. This shows that the change of the acid radical ion amount in the method can regulate the mesoporous pore diameter.

In addition, as can be seen from Table 2, the hierarchical pore-containing Y-type molecular sieve prepared by this method has an increased acid content and an increased B-acid strength to a different extent than those before the treatment.

TABLE 3 Table 3

As seen from Table 3, the product passes through Cs ⁺ 、Rb ⁺ 、Sr ²⁺ 、Ba ²⁺ The surface dealumination of the sample subjected to acid treatment after exchange is obviously reduced, wherein Cs ⁺ 、Rb ⁺ The surface protection effect is obvious, so that the surface silicon-aluminum ratio of the sample E, F is obviously smaller than the bulk silicon-aluminum ratio; and Sr ²⁺ 、Ba ²⁺ The surface protection was weaker, and the surface silicon to aluminum ratio of sample G, H of examples 7 and 8 was still greater than or similar to the bulk silicon to aluminum ratio, but was significantly lower than that of the comparative examples. Through Na ⁺ Sample DB5 of comparative example 5, which was acid treated after exchange, showed no significant difference from samples A-C of sample examples 1-3, and showed severe surface dealumination; sample I is subjected to high concentration of Cs ⁺ Exchange and low-concentration acid treatment, the dealumination degree is light, and Cs is the same as that of the aluminum ⁺ The lower surface is protected from dealumination; sample J is subjected to low concentration Cs ⁺ Exchange and high concentration acid sitesIn principle, the degree of dealumination is severe, but Cs can still be seen ⁺ Protection of surface aluminum. The optimal metal ion with uniform aluminum distribution can be selected as Cs ⁺ Or Rb ⁺ The concentration of the optimal metal ion solution is 0.5-1 mol/L.

The preferred technical proposal for obtaining the Y-type molecular sieve containing hierarchical pores is NH ₄ Y passing through Cs ⁺ 、Rb ⁺ 、Sr ²⁺ 、Ba ²⁺ The acid treatment is carried out easily by using acid which contains hydrogen ions and at least two different carboxylate ions and has the pH value of 4.5-5.5 after the exchange, and the technical effect is that the multistage pore is obtained and the aluminum distribution is uniform.

The following examples illustrate the preparation process and the catalysts obtained according to the invention.

Examples 11 to 20

Adding acid into quantitative hydrated alumina under stirring, adding clay, pulping for 10 minutes under high shearing, mixing uniformly, adding the hierarchical pore Y-type molecular sieve samples A-J, and finally adding aluminum sol, silica sol and water. Kneading, extruding, rolling and sieving the obtained slurry. The catalyst numbers corresponding to the catalysts containing the hierarchical pore Y-type molecular sieve samples A-J are a-J.

The slurry dry basis composition, slurry solids content, alumina content provided by hydrated alumina and alumina sol, and silica content provided by silica sol are given in table 4.

Table 5 gives various parameters of catalyst surface area, pore and strength.

Comparative examples 6 to 10

The difference from example 11 is the comparative Y molecular sieve samples DB 1-DB 5 of comparative examples 1-5. The corresponding comparative catalysts are numbered Z1 to Z5.

Table 5 gives various parameters of catalyst surface area, pore and strength.

TABLE 4 Table 4

TABLE 5

Claims

1. A preparation method of a catalyst containing a hierarchical pore Y-type molecular sieve is characterized by comprising the steps of contacting the Y-type molecular sieve with an acidic solution containing hydrogen ions and at least two different carboxylate ions, regulating the pH value to be 4.5-5.5, filtering, washing and drying to obtain the hierarchical pore Y-type molecular sieve, and then mixing with a matrix material; wherein the Y-type molecular sieve is NH ₄ The Y molecular sieve is contacted with a salt solution containing alkali metal ions and/or a salt solution containing alkaline earth metal ions, and the product is obtained after filtering, washing and drying, wherein the alkali metal is selected from rubidium and cesium, and the alkaline earth metal is selected from strontium and barium.

2. The method according to claim 1, wherein the base material is one or more selected from the group consisting of alumina, silica and clay.

3. The process according to claim 1, wherein the hierarchical pore-containing Y-type molecular sieve is present in an amount of 38 to 90% by weight based on the dry weight of the catalyst.

4. The process according to claim 1, wherein the ratio of the acidic solution to the Y-type molecular sieve is 8 to 25:1, wherein the acidic solution is calculated in mL, and the Y-type molecular sieve is calculated in g.

5. The production method according to claim 1, wherein the carboxylate ion is at least two selected from the group consisting of oxalate ion, lactate ion and citrate ion.

6. The process according to claim 1, wherein the carboxylate ions are each present in a concentration of 0.1 to 0.5mol/L.

7. The process according to claim 1, wherein the contacting of the Y-type molecular sieve with an acidic solution is carried out at a temperature of 20 to 100 ℃ for 1 to 12 hours.

8. The preparation method according to claim 1, wherein the carboxylate ions are oxalate ions and lactate ions, and the ratio of the oxalate ions to the lactate ions is 0.4 to 2.5 in terms of carboxylate ion mole: 1.

9. the process according to claim 1, wherein the alkali metal ion-containing salt solution is selected from the group consisting of rubidium chloride, cesium chloride, rubidium nitrate, cesium nitrate, rubidium sulfate and cesium sulfate, and the alkaline earth metal ion-containing salt solution is selected from the group consisting of strontium chloride, barium chloride and strontium nitrate.

10. The production method according to claim 1, wherein the alkali metal ion-containing salt solution or alkaline earth metal ion-containing salt solution has a concentration of 0.1 to 2mol/L.

11. The process according to claim 1, wherein the NH is ₄ The Y molecular sieve is contacted with the salt solution containing alkali metal ions and/or the salt solution containing alkaline earth metal ions for 0.2 to 2 hours at the temperature of 20 to 80 ℃.

12. The process according to claim 1, wherein the step of mixing the hierarchical pore-containing Y-type molecular sieve with the matrix material comprises mixing the hierarchical pore-containing Y-type molecular sieve with hydrated alumina, alumina sol, silica sol, acid, water and optionally clay to obtain a slurry having a solid content of 35 to 40%.

13. The method according to claim 12, wherein the hydrated alumina is pseudo-boehmite and/or gibbsite.

14. The process according to claim 12, wherein the acid is selected from the group consisting of hydrochloric acid, nitric acid and phosphoric acid.

15. The method of claim 1 wherein the mixing with the matrix material is performed by adding acid to the pseudo-boehmite, adding clay, mixing uniformly, adding a Y-type molecular sieve containing hierarchical pores, and adding alumina sol, silica sol and water.

16. A catalyst comprising a hierarchical pore Y-type molecular sieve obtained by the process of any one of claims 1 to 15.

17. The catalyst according to claim 16, having a micropore specific surface area of 400 to 650m ² Per gram, the micropore volume is 0.25-0.35 cm ³ Per gram, the specific surface area of the mesoporous is 30 to 200m ² Per g, mesoporous volume of 0.07-0.85 cm ³ And/g, the mesoporous aperture is 2.0-6.0 nm, and the intensity is 8.5-13.5N/mm.