A modified Y-type molecular sieve and its preparation method

Abstract

A method for preparing a modified Y-type molecular sieve comprises the following steps: S1, mixing REY molecular sieve and AlCl3 solid evenly in a dry atmosphere; S2, passing air through the mixture of REY molecular sieve and AlCl3 solid, reacting at 50-350°C for 0.5-12 hours, and purging with nitrogen for 1-5 hours after the reaction is completed; and S3, washing and drying to obtain the modified Y-type molecular sieve. The present invention treats the rare earth exchanged REY molecular sieve by a new gas phase dealumination method, and the prepared modified Y-type molecular sieve product contains rare earth elements, and compared with silicon tetrachloride gas phase dealumination and siliconization, has more developed mesoporous channels, and is more suitable as an active component in a catalyst for treating heavy and inferior oil products.

Description

Technical Field

[0001] The invention belongs to the field of catalysts, and in particular relates to a modified Y-type molecular sieve and a preparation method thereof. Background Art

[0002] In catalytic cracking catalysts, molecular sieves with high silicon-aluminum ratio are important active components, and their performance directly affects the reaction performance of catalytic cracking catalysts. The preparation of molecular sieves with high silicon-aluminum ratio mainly includes hydrothermal dealumination, ammonium fluorosilicate dealumination and siliconization, and gas phase dealumination and siliconization. The hydrothermal method is the most commonly used method in industry at present. However, this method is prone to lattice collapse, and the non-framework aluminum produced will block the pores, affecting the accessibility of the active center. The ammonium fluorosilicate method of dealumination and siliconization can obtain molecular sieves with high crystallinity, silicon-aluminum ratio and thermal stability while siliconization, but the operating conditions are harsh, and insoluble AlF3 will be formed during the process, and it will pollute the environment. The gas phase dealumination and siliconization method can obtain products with complete crystal structure and high relative crystal retention, but there are no mesoporous channels in the product, and SiCl4 is highly corrosive when it comes into contact with water, and the generated NaAlCl4 will seriously block the pores, reducing the accessibility of the acidic sites of the molecular sieve.

[0003] The most commonly used elements for molecular sieve modification are rare earths, which can increase the acid density and strength, inhibit the dealumination and structural collapse of the molecular sieve framework, and improve the structural stability and activity of the molecular sieve.

[0004] Patent CN102452658A discloses a method for continuous contact reaction of molecular sieve and SiCl4 gas, and also discloses a tubular reactor. The molecular sieve contacts the gas phase SiCl4 in the gas under a flowing state, and the contact temperature of the molecular sieve and the gas phase SiCl4 is 250-700°C, and the contact time is 10 seconds to 100 minutes. In this inventive method, the contact temperature, reaction conditions and reaction degree are controllable. Moreover, the molecular sieve is evenly mixed with the gas containing the gas phase SiCl4, which ensures that the silicon replenishment reaction can be carried out evenly and fully. However, the realization of this process requires the construction of a new special reactor, and the obtained product also has no mesoporous channels, and there is also the problem of NaAlCl4 blocking the channels.

[0005] Patent CN1127161A discloses a method for preparing rare earth-containing silicon-rich ultra-stable Y-type molecular sieve by ultra-stabilization of NaY and rare earth ion exchange in one step. Using NaY as raw material, SiCl4 is used to carry out gas phase dealumination and silicon replenishment reaction in the presence of solid ReCl3. After mixing NaY molecular sieve and solid RECl3, SiCl4 carried by dry air is introduced, and reacted in a reactor at 150-550°C for 10 minutes to 5 hours. After the reaction, dry air is purged in the reactor for 10 minutes to 2 hours, and then washed and filtered to obtain the product. This method reduces the preparation process of rare earth-containing ultra-stable Y-type molecular sieve, but the process conditions are strict, especially the water content in the solid mixture raw material and the gas is reduced as much as possible to reduce the corrosiveness during the operation.

[0006] Since the traditional dealumination method of Y-type molecular sieve has some shortcomings in process or product properties, and rare earth elements are currently necessary for the preparation of catalytic cracking catalysts, it is necessary to develop a new preparation method of rare earth-containing Y molecular sieve. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing a modified Y-type molecular sieve, so as to solve the problems of complicated operation and harsh reaction conditions in the preparation method of the prior art.

[0008] The present invention also aims to provide a modified Y-type molecular sieve.

[0009] To achieve the above object, the present invention provides a method for preparing a modified Y-type molecular sieve, comprising the following steps:

[0010] S1, mixing REY molecular sieve and AlCl3 solid evenly under dry atmosphere;

[0011] S2, passing air into the mixture of REY molecular sieve and AlCl3 solid, reacting at 50-350°C for 0.5-12 hours, and purging with nitrogen for 1-5 hours after the reaction is completed; and

[0012] S3, after washing and drying, the modified Y-type molecular sieve is obtained.

[0013] AlCl3 solid contains a certain amount of crystalline water, which can be slowly released to obtain gaseous HCl molecules by controlling the reaction temperature at medium and high temperatures. It can be used for controllable dealumination of NaY molecular sieves, and a certain amount of mesopores can also be obtained.

[0014] The preparation method of the modified Y-type molecular sieve of the present invention, wherein the preparation method of the REY molecular sieve is: Y molecular sieve and rare earth solution are ion exchanged for 0.5 to 5 hours at 20 to 90° C. and pH 3.0 to 5.0, and the REY molecular sieve is obtained after filtering, washing and drying.

[0015] The preparation method of the modified Y-type molecular sieve described in the present invention, wherein the Y molecular sieve is not limited to the original NaY molecular sieve, and can be applicable to Y-type molecular sieves treated by different treatment methods, preferably one or more of NaY molecular sieve, NH4Y molecular sieve and HY molecular sieve.

[0016] The preparation method of the modified Y-type molecular sieve of the present invention, wherein the grain size of the Y molecular sieve is 400-1000nm, and the silicon-aluminum ratio of the Y molecular sieve is 3-6 based on the molar ratio of SiO2 and Al2O3.

[0017] The preparation method of the modified Y-type molecular sieve of the present invention, wherein the silicon-aluminum ratio of the Y molecular sieve is 5-6 based on the molar ratio of SiO2 and Al2O3.

[0018] The preparation method of the modified Y-type molecular sieve of the present invention, wherein, in the preparation process of the REY molecular sieve, the mass ratio of the Y molecular sieve dry basis: RE2O3: water is 1:0.10-0.20:50-120.

[0019] The method for preparing the modified Y-type molecular sieve of the present invention, wherein, based on 100% mass of the REY molecular sieve, the Na2O content in the REY molecular sieve is 0.5-3.0%.

[0020] In the preparation method of the modified Y-type molecular sieve of the present invention, in step S1, the mass ratio of REY molecular sieve to AlCl3 solid is 1:0.005-0.1. If the AlCl3 solid content is too low, the requirement of sufficient ultra-stable dealumination cannot be achieved.

[0021] In the preparation method of the modified Y-type molecular sieve of the present invention, in step S1, the water content of the REY molecular sieve and the AlCl3 solid is less than 10 wt%. The dealumination process of the REY molecular sieve of the present invention is carried out in a gas phase environment. If the water content is too high, water vapor will be generated after the air is introduced, and a hydrothermal atmosphere will be formed at high temperature, which is not conducive to the control of the dealumination degree. In addition, if the AlCl3 contains too much water, it will be partially hydrolyzed, resulting in only a part of the effect.

[0022] The method for preparing the modified Y-type molecular sieve of the present invention, wherein, in step S1, the water content of the REY molecular sieve and the AlCl3 solid is both less than 5 wt%.

[0023] The preparation method of the modified Y-type molecular sieve of the present invention, wherein in step S2, the temperature is uniformly increased to 50-350°C, and the heating rate is 0.5°C / min-10°C / min. The uniform heating rate and the heating rate are set to slowly release the crystal water of AlCl3, ensuring a smooth process and easy operation.

[0024] In the method for preparing the modified Y-type molecular sieve of the present invention, the air introduction rate in step S2 is 30-60 ml / min. The introduction rate can ensure that the air can have sufficient contact with the mixture of the molecular sieve and the AlCl3 solid, and ensure that the solid mixture is not blown away.

[0025] The method for preparing the modified Y-type molecular sieve of the present invention comprises the following steps: in step S3, washing is performed with deionized water or an ammonia solution.

[0026] The method for preparing the modified Y-type molecular sieve of the present invention, wherein in step S3, the drying condition is 70-150° C., and the drying time is 4-16 hours.

[0027] To achieve the above object, the present invention also provides a modified Y-type molecular sieve, which is prepared by the above method. Based on 100% mass of the modified Y-type molecular sieve, the Na2O content in the modified Y-type molecular sieve is 0.5-2.5%, the unit cell constant is 2.440-2.450, the crystal retention degree is ≥75%, and the mesopore volume is ≥0.04 ml / g.

[0028] The beneficial effects of the present invention are:

[0029] The invention uses a novel gas phase dealumination method to treat rare earth exchanged REY molecular sieves. The prepared modified Y-type molecular sieve product contains rare earth elements and has more developed mesoporous channels compared with silicon tetrachloride gas phase dealumination and siliconization, and is more suitable as an active component in a catalyst for treating heavy and inferior oil products. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the preparation method of the modified Y-type molecular sieve of the present invention;

[0031] Figure 2 It is a schematic diagram of the preparation method of REY molecular sieve of the present invention. DETAILED DESCRIPTION

[0032] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0033] In each embodiment and comparative example, the Na2O content was determined by X-ray fluorescence spectroscopy.

[0034] The relative crystallinity and unit cell constant of the synthesized NaY zeolite were determined using a BRUKER D8 ADVANCE (Bruker, Germany) X-ray diffractometer under the following experimental conditions: CuKa radiation (0.1541 nm), tube voltage 40 kV, and tube current 40 mA.

[0035] The relative crystallinity was determined according to the standard method SH / T 0340-92 (Compilation of Chemical Industry Standards, China Standards Press, published in 2000).

[0036] The zeolite standard sample used as the crystallinity standard in the examples and comparative examples is derived from the industrial NaY reference sample No. 040617, and its crystallinity is set to 100%.

[0037] Relative crystallinity retention = (relative crystallinity of Y-type molecular sieve obtained by the inventive method / relative crystallinity of original Y molecular sieve) × 100%

[0038] The pore volume of the molecular sieve is determined by low-temperature nitrogen adsorption method. According to the RIPP151-90 standard method "Petrochemical Analysis Method (RIPP Test Method)", the total pore volume of the molecular sieve is determined according to the adsorption isotherm, and then the micropore volume of the molecular sieve is determined from the adsorption isotherm according to the T plot method. The total pore volume minus the micropore volume is taken as the mesopore volume.

[0039] A method for preparing a modified Y-type molecular sieve comprises the following steps:

[0040] S1, mixing REY molecular sieve and AlCl3 solid evenly under dry atmosphere;

[0041] S2, passing air into the mixture of REY molecular sieve and AlCl3 solid, reacting at 50-350°C for 0.5-12 hours, and purging with nitrogen for 1-5 hours after the reaction is completed; and

[0042] S3, after washing and drying, a modified Y-type molecular sieve is obtained.

[0043] AlCl3 solid contains a certain amount of crystalline water, which can be slowly released to obtain gaseous HCl molecules by controlling the reaction temperature at medium and high temperatures. It can be used for controllable dealumination of NaY molecular sieves, and a certain amount of mesopores can also be obtained.

[0044] The preparation method of the modified Y-type molecular sieve of the present invention, wherein the preparation method of the REY molecular sieve is: Y molecular sieve and rare earth solution are ion exchanged for 0.5 to 5 hours at 20 to 90° C. and pH 3.0 to 5.0, and the REY molecular sieve is obtained after filtering, washing and drying.

[0045] The preparation method of the modified Y-type molecular sieve described in the present invention, wherein the Y molecular sieve is not limited to the original NaY molecular sieve, and can be applicable to Y-type molecular sieves treated by different treatment methods, preferably one or more of NaY molecular sieve, NH4Y molecular sieve and HY molecular sieve.

[0046] The preparation method of the modified Y-type molecular sieve of the present invention, wherein the grain size of the Y molecular sieve is 400-1000nm, and the silicon-aluminum ratio of the Y molecular sieve is 3-6 based on the molar ratio of SiO2 and Al2O3.

[0047] The preparation method of the modified Y-type molecular sieve of the present invention, wherein the silicon-aluminum ratio of the Y molecular sieve is 5-6 based on the molar ratio of SiO2 and Al2O3.

[0048] The preparation method of the modified Y-type molecular sieve of the present invention, wherein, in the preparation process of the REY molecular sieve, the mass ratio of the Y molecular sieve dry basis: RE2O3: water is 1:0.10-0.20:50-120.

[0049] The method for preparing the modified Y-type molecular sieve of the present invention, wherein, based on 100% mass of the REY molecular sieve, the Na2O content in the REY molecular sieve is 0.5-3.0%.

[0050] In the preparation method of the modified Y-type molecular sieve of the present invention, in step S1, the mass ratio of REY molecular sieve to AlCl3 solid is 1:0.005-0.1. If the AlCl3 solid content is too low, the requirement of sufficient ultra-stable dealumination cannot be achieved.

[0051] In the preparation method of the modified Y-type molecular sieve of the present invention, in step S1, the water content of the REY molecular sieve and the AlCl3 solid is less than 10 wt%. The dealumination process of the REY molecular sieve of the present invention is carried out in a gas phase environment. If the water content is too high, water vapor will be generated after the air is introduced, and a hydrothermal atmosphere will be formed at high temperature, which is not conducive to the control of the dealumination degree. In addition, if the AlCl3 contains too much water, it will be partially hydrolyzed, resulting in only a part of the effect.

[0052] The method for preparing the modified Y-type molecular sieve of the present invention, wherein, in step S1, the water content of the REY molecular sieve and the AlCl3 solid is both less than 5 wt%.

[0053] The preparation method of the modified Y-type molecular sieve of the present invention, wherein in step S2, the temperature is uniformly increased to 50-350°C, and the heating rate is 0.5°C / min-10°C / min. The uniform heating rate and the heating rate are set to slowly release the crystal water of AlCl3, ensuring a smooth process and easy operation.

[0054] In the method for preparing the modified Y-type molecular sieve of the present invention, the air introduction rate in step S2 is 30-60 ml / min. The introduction rate can ensure that the air can have sufficient contact with the mixture of the molecular sieve and the AlCl3 solid, and ensure that the solid mixture is not blown away.

[0055] The method for preparing the modified Y-type molecular sieve of the present invention comprises the following steps: in step S3, washing is performed with deionized water or an ammonia solution.

[0056] The method for preparing the modified Y-type molecular sieve of the present invention, wherein in step S3, the drying condition is 70-150° C., and the drying time is 4-16 hours.

[0057] The present invention also provides a modified Y-type molecular sieve, which is prepared by the above method. Based on 100% mass of the modified Y-type molecular sieve, the Na2O content in the modified Y-type molecular sieve is 0.5-2.5%, the unit cell constant is 2.440-2.450, the crystal retention degree is ≥75%, and the mesopore volume is ≥0.04 ml / g.

[0058] Specifications of raw materials used in the embodiments and comparative examples:

[0059] Rare earth chloride solution: lanthanum chloride reagent (calculated as La2O3) and water are prepared in a mass ratio of 1:660.

[0060] Unless otherwise specified, the chemical reagents used in the embodiments and comparative examples were of analytical grade.

[0061] Example 1

[0062] In a beaker, add 200g (dry basis) NaY molecular sieve with an average grain size of 400~500nm and a silicon-aluminum ratio of 5.6 and 20kg deionized water, stir evenly, slowly add 0.12L of rare earth chloride solution, adjust pH=3.5~4.5, exchange at 80℃ for 1.0h, filter, wash and dry to obtain REY molecular sieve with a water content of <5wt% and a Na2O content of 0.7411%. While hot, mix REY molecular sieve and 2.4g AlCl3 solid with a water content of 1.8wt% and put it into the reactor, introduce air into the reactor, the air introduction rate is 50ml / min, the temperature is uniformly heated to 250℃ at a heating rate of 5℃ / min, the reaction time is 45min, and then purged with nitrogen for 2h. After taking out the molecular sieve, wash the soluble impurities with deionized water, and obtain Y-type molecular sieve after drying, which is recorded as Y1.

[0063] Example 2

[0064] In a beaker, add 200g (dry basis) NaY molecular sieve with an average grain size of 500~600nm and a silicon-aluminum ratio of 5.2 and 20kg deionized water, stir evenly, slowly add 0.10L rare earth chloride solution, adjust pH=3.5~4.5, exchange at 60℃ for 2.5h, filter, wash and dry to obtain REY molecular sieve with a water content of <5wt% and a Na2O content of 0.9612%. While hot, mix REY molecular sieve and 2.1g AlCl3 solid with a water content of 0.75wt% and put it into the reactor, introduce air into the reactor, the air introduction rate is 50ml / min, the temperature is uniformly heated to 200℃ at a heating rate of 1℃ / min, the reaction time is 3h, and then purged with nitrogen for 2h. After taking out the molecular sieve, wash the soluble impurities with deionized water, and obtain Y-type molecular sieve after drying, which is recorded as Y2.

[0065] Example 3

[0066] In a beaker, add 200g (dry basis) NaY molecular sieve with an average grain size of 400~500nm and a silicon-aluminum ratio of 4.9 and 20kg deionized water, stir evenly, slowly add 0.16L of rare earth chloride solution, adjust pH=4.0~5.0, exchange at 20℃ for 5.0h, filter, wash and dry to obtain REY molecular sieve with a water content of <5wt% and a Na2O content of 2.3118%. While hot, mix REY molecular sieve and 5.8g AlCl3 solid with a water content of 3.02wt% and put them into the reactor, introduce air into the reactor at a rate of 40ml / min, and uniformly increase the temperature to 300℃ at a rate of 0.5℃ / min. The reaction time is 5.0h, and then purged with nitrogen for 3h. After taking out the molecular sieve, wash the soluble impurities with deionized water, and obtain Y-type molecular sieve after drying, which is recorded as Y3.

[0067] Example 4

[0068] In a beaker, add 200g (dry basis) HY molecular sieve with an average grain size of 800~900nm and a silicon-aluminum ratio of 4.4 and 20kg deionized water, stir evenly, slowly add 0.16L of rare earth chloride solution, adjust pH=3.5~4.0, exchange at 85℃ for 1.0h, filter, wash and dry to obtain REY molecular sieve with a water content of <5wt% and a Na2O content of 0.6351%. While hot, mix REY molecular sieve and 8.8g AlCl3 solid with a water content of 0.4417wt% and put it into the reactor, introduce air into the reactor, the air introduction rate is 60ml / min, the temperature is uniformly heated to 350℃ at a heating rate of 10℃ / min, the reaction time is 1.0h, and then purged with nitrogen for 5h. After taking out the molecular sieve, wash the soluble impurities with deionized water, and obtain Y-type molecular sieve after drying, which is recorded as Y5.

[0069] Comparative Example 1

[0070] In a beaker, add 200g (dry basis) NaY molecular sieve with an average grain size of 400~500nm and a silicon-aluminum ratio of 5.6 and 20kg deionized water, stir evenly, slowly add 0.12L rare earth chloride solution, adjust pH=3.5~4.5, exchange at 80℃ for 1.0h, filter, wash and dry to obtain REY molecular sieve with a water content of <5wt% and a Na2O content of 0.7411%. Put the REY molecular sieve into a tubular furnace, pass nitrogen, check for leaks, and after preparation, set the reactor to heat up, maintain the temperature at 500℃ for 2h, then cool down, and pass N2 saturated with SiCl4 when the temperature drops to 115℃. After heating to 250℃ at a heating rate of 3℃ / min for 45min, stop passing N2 saturated with SiCl4 and continue to purge for 2h, stop heating and cool to room temperature, and prepare the Y-type molecular sieve after washing and drying the sample, recorded as Y6.

[0071] Comparative Example 2

[0072] In a beaker, add 200g (dry basis) NaY molecular sieve with an average grain size of 400~500nm and a silicon-aluminum ratio of 5.6 and 20kg deionized water, stir evenly, slowly add 0.12L rare earth chloride solution, adjust pH=3.5~4.5, exchange at 80℃ for 1.0h, filter, wash and dry to obtain REY molecular sieve with a water content of <5wt% and a Na2O content of 0.7411%. The REY molecular sieve is hydrothermally calcined at 800℃ and 100% water vapor for 1h to obtain a Y-type molecular sieve after dealuminization, recorded as Y7.

[0073] The Y molecular sieve product obtained in the embodiment of the present invention was subjected to relevant characterization tests, and the results are listed in Table 1.

[0074] Table 1 shows the Na2O content, unit cell constant, relative crystal retention, and medium and macropore volume data of the prepared Y molecular sieve.

[0075] Table 1

[0076]

[0077] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a modified Y-type molecular sieve used as a catalyst active component for treating heavy and inferior oil products, characterized in that: The following steps are involved: S1, mixing REY molecular sieve and AlCl3 solid evenly under dry atmosphere; S2, passing air into the mixture of REY molecular sieve and AlCl3 solid, reacting at 200-350°C for 0.5-12 hours, and purging with nitrogen for 1-5 hours after the reaction is completed; and S3, washing and drying to obtain a modified Y-type molecular sieve; In step S1, the mass ratio of REY molecular sieve to AlCl3 solid is 1:0.005-0.1; In step S1, the water content of REY molecular sieve and AlCl3 solid is less than 5 wt%; In step S2, the temperature is uniformly increased to 200-350°C, and the heating rate is 0.5°C / min-10°C / min; The modified Y-type molecular sieve has a unit cell constant of 2.440-2.450, a crystal retention degree of ≥75%, and a mesopore volume of ≥0.04 ml / g.

2. The method for preparing the modified Y-type molecular sieve according to claim 1, characterized in that: The preparation method of the REY molecular sieve is as follows: Y molecular sieve and rare earth solution are ion exchanged for 0.5 to 5 hours at 20 to 90° C. and pH 3.0 to 5.0, and the REY molecular sieve is obtained after filtering, washing and drying.

3. The method for preparing the modified Y-type molecular sieve according to claim 2, characterized in that: The Y molecular sieve is one or more of NaY molecular sieve, NH4Y molecular sieve and HY molecular sieve.

4. The method for preparing the modified Y-type molecular sieve according to claim 2 or 3, characterized in that: The grain size of the Y molecular sieve is 400-1000 nm, and the silicon-aluminum ratio of the Y molecular sieve is 3-6 based on the molar ratio of SiO2 and Al2O3.

5. The method for preparing the modified Y-type molecular sieve according to claim 4, characterized in that: Calculated by the molar ratio of SiO2 to Al2O3, the silicon-to-aluminum ratio of the Y molecular sieve is 5-6.

6. The method for preparing the modified Y-type molecular sieve according to claim 2, characterized in that: During the preparation of REY molecular sieve, the mass ratio of Y molecular sieve dry basis: RE2O3: water is 1:0.10~0.20:50~120.

7. The method for preparing the modified Y-type molecular sieve according to claim 1 or 2, characterized in that: Based on 100% mass of the REY molecular sieve, the Na2O content in the REY molecular sieve is 0.5-3.0%.

8. The method for preparing the modified Y-type molecular sieve according to claim 1, characterized in that: The air introduction rate in step S2 is 30-60 ml / min.

9. The method for preparing the modified Y-type molecular sieve according to claim 1, characterized in that: In step S3, washing is performed with deionized water or an ammonia solution.

10. A modified Y-type molecular sieve used as a catalyst active component for treating heavy and inferior oil products, characterized in that: The modified Y-type molecular sieve is prepared by the method according to any one of claims 1 to 9, wherein the modified Y-type molecular sieve has a Na2O content of 0.5 to 2.5%, a unit cell constant of 2.440 to 2.450, a crystal retention degree of ≥75%, and a mesopore volume of ≥0.04 ml / g based on 100% of the mass of the modified Y-type molecular sieve.

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