A modified y-type molecular sieve rich in secondary pores and a method for preparing the same

Abstract

The application relates to a modified Y-type molecular sieve rich in secondary pores and a preparation method thereof, wherein the skeleton silicon aluminum ratio of the modified Y-type molecular sieve is 11-47 in terms of the SiO2 / Al2O3 molar ratio; the modified Y-type molecular sieve is rich in secondary pores, the pore diameter of the secondary pores is 2-100 nm, the pore volume percentage of the secondary pores in the total pore volume is 35-50%, the specific surface area of the modified Y-type molecular sieve is not less than 675 m 2 / g, and the relative crystallinity of the modified Y-type molecular sieve is not less than 75%. The preparation method of the modified Y-type molecular sieve comprises the steps that a NaY molecular sieve filter cake is contacted with a NaY mother liquor under stirring, and a dilute acid aqueous solution is slowly added. The preparation method of the modified Y-type molecular sieve can not only improve the crystallinity and heavy oil conversion capacity of the Y-type molecular sieve, but also improve the recovery rate of the NaY mother liquor, reduces the production cost, and reduces the wastewater and waste residue emissions of catalyst production enterprises.

Description

TECHNICAL FIELD

[0001] The present application relates to a modified Y-type molecular sieve and a preparation method thereof. Further, the present application relates to a modified Y-type molecular sieve rich in secondary pores and a preparation method thereof. BACKGROUND

[0002] It is known that molecular sieves with secondary pores have higher accessibility of active sites, thus making the corresponding catalysts have better catalytic performance.

[0003] CN 1127161 discloses a preparation method of a rare earth-containing silicon-rich ultra-stable Y-type molecular sieve. The method is to use SiCl4 to perform gas phase dealumination and silicon supplementation in the presence of solid RECl3, thus completing the ultra-stabilization and rare earth ion exchange of NaY in one step. The molecular sieve prepared according to the method has a unit cell constant a of 2.430-2.460 nm, a rare earth content of 0.15-10.0 wt%, and a Na2O content of less than 1.0%. However, the molecular sieve is prepared only by a gas phase ultra-stabilization method. Although the ultra-stable Y molecular sieve containing rare earth can be prepared, the prepared molecular sieve lacks secondary pores. o

[0004] The hydrothermal ultra-stabilization method is one of the most widely used modification methods for Y-type molecular sieves in industry. The method first exchanges NaY zeolite with an aqueous solution of ammonium ions to reduce the sodium ion content in the zeolite, and then calcines the ammonium ion-exchanged zeolite at 500-800°C in a water vapor atmosphere to make it ultra-stable. This method has low cost and is easy to industrialize and mass produce, but has the disadvantage that the crystallinity of the ultra-stable Y zeolite is severely lost, and it is difficult to prepare a hydrothermal ultra-stable molecular sieve with a high framework silica-alumina ratio and high crystallinity and small unit cell.

[0005] On the other hand, the method of forming a silicon-aluminum hydrogel is currently mainly used in industrial NaY production to recover silicon in the mother liquor. However, this method has the following main disadvantages: (1) The NaY mother liquor in actual industrial production inevitably contains part of P-type crystal microcrystals. In order to avoid the adverse effects of P-type crystal seeds in the recovered silicon-aluminum gel on the synthesis system, the proportion of the recovered silicon source is limited, generally not more than 25%, and the silicon utilization rate is only about 75%, so the silicon in the mother liquor cannot be completely recovered; (2) When the recovered solid silicon-aluminum gel is mixed with the liquid silicon-aluminum source in the raw material tank to prepare a synthesis gel, it is difficult to achieve uniformity of the gel system composition, and P-type crystal formation is easily induced during the crystallization process, leading to unstable production process of NaY synthesis; (3) The average particle size of the NaY molecular sieve synthesized based on part of the recovered silicon-aluminum gel is reduced, leading to a decrease in product quality and possibly causing adverse effects on the hydrothermal stability in the subsequent use process.

[0006] ​In summary, the existing hydrothermal super-stable technology is difficult to prepare Y-type molecular sieve with high framework silica-alumina ratio, high crystallinity and rich secondary pores, and it is difficult to achieve higher NaY mother liquor recovery rate. SUMMARY

[0007] One of the technical problems to be solved by the present application is to provide a modified Y-type molecular sieve rich in secondary pores, which not only is rich in secondary pores, has high framework silica-alumina ratio, high crystallinity, but also has higher hydrothermal stability, and still has high relative crystallinity retention after harsh aging conditions.

[0008] According to a first aspect of the present application, the present application provides a modified Y-type molecular sieve rich in secondary pores, wherein the rare earth content of the modified Y-type molecular sieve is 0.5-9wt% based on the total weight of the dry basis of the Y-type molecular sieve, the sodium content of the modified Y-type molecular sieve is not more than 0.3wt% based on sodium oxide, the framework silica-alumina ratio of the modified Y-type molecular sieve is 11-47 based on the molar ratio of SiO2 / Al2O3, preferably 12-38; the modified Y-type molecular sieve is rich in secondary pores, the pore size of the secondary pores is 2-100nm, the pore volume of the secondary pores accounts for 35-50% of the total pore volume, preferably 36-46%; the specific surface area of the modified Y-type molecular sieve is not less than 675m 2 / g, preferably 675-695m 2 / g; the relative crystallinity of the modified Y-type molecular sieve is not less than 75%, preferably 76-83%; the lattice collapse temperature of the modified Y-type molecular sieve is not less than 1080℃, preferably 1080℃-1100℃.

[0009] According to an embodiment of the present application, the unit cell constant of the modified Y-type molecular sieve is 2.426-2.444nm, preferably 2.428-2.442nm.

[0010] According to an embodiment of the present application, the total pore volume is 0.39-0.51mL / g, preferably 0.42-0.49mL / g.

[0011] According to an embodiment of the present application, the secondary pores include larger secondary pores, the pore size of the larger secondary pores is 8-100nm; the pore volume of the larger secondary pores accounts for 68-85% of the total secondary pore volume, preferably 70-83%.

[0012] Another technical problem to be solved by the present application is to provide a method for preparing a modified Y-type molecular sieve rich in secondary pores, which can not only maximize the recycling of the remaining silicon source in the NaY mother liquor, thereby reducing costs, reducing emissions, and protecting the environment, but also overcome the shortcomings of the existing hydrothermal ultrastable technology, and prepare a Y-type molecular sieve with high framework silica-alumina ratio, high crystallinity, and rich in secondary pores.

[0013] According to a second aspect of the present application, the present application provides a method for preparing the modified Y-type molecular sieve rich in secondary pores according to the first aspect, comprising the following steps:

[0014] (1) contacting NaY molecular sieve with NaY mother liquor to be recycled, adding dilute acid aqueous solution, and optionally stirring and filtering;

[0015] (2) contacting the NaY molecular sieve obtained in step (1) with a rare earth salt solution to perform ion exchange reaction, and optionally filtering and washing to obtain a Y-type molecular sieve containing rare earth elements with reduced sodium oxide content;

[0016] (3) subjecting the Y-type molecular sieve containing rare earth elements with reduced sodium oxide content to a mild hydrothermal ultrastable modification treatment, and optionally drying to obtain a Y-type molecular sieve with reduced unit cell constant;

[0017] (4) contacting the Y-type molecular sieve with reduced unit cell constant with silicon tetrachloride gas to react, and optionally washing and filtering to obtain an ultrastable modified Y-type molecular sieve;

[0018] (5) contacting the gas-phase ultrastable modified Y-type molecular sieve obtained in step (4) with an acid solution to perform channel cleaning modification.

[0019] According to an embodiment of the present application, the dilute acid aqueous solution in step (1) is dilute hydrochloric acid or dilute sulfuric acid or dilute nitric acid, and the concentration of the dilute acid aqueous solution is 0.001 to 0.1 mol / L in terms of the molar concentration of H + in the solution; preferably 0.005 to 0.05 mol / L.

[0020] According to an embodiment of the present application, the volume ratio of the dilute acid aqueous solution in step (1) to the NaY mother liquor is (0.5-1.5):1.

[0021] According to an embodiment of the present application, the ratio of the NaY mother liquor to the NaY molecular sieve in step (1) is 1-1.9 mL of NaY mother liquor:1 g of NaY molecular sieve.

[0022] According to one embodiment of the present application, in step (2), the rare earth salt solution is an aqueous solution of a rare earth salt; and preferably, the rare earth salt is a rare earth chloride and / or a rare earth nitrate; the rare earth content in the rare earth element-containing Y-type molecular sieve with reduced sodium oxide content is 6.5-14 wt% as RE2O3, wherein RE represents a rare earth element; the sodium oxide content is 4-8 wt%, for example, 4.5-7.5 wt%, and the unit cell constant is 2.465-2.472 nm.

[0023] According to one embodiment of the present application, in step (3), the mild hydrothermal super-stable modification treatment comprises calcining the Y-type molecular sieve at a temperature of 350-550°C in an atmosphere containing 40-95 vol% water vapor for 4.5-7 hours; and optionally drying.

[0024] According to one embodiment of the present application, in step (3), the unit cell constant of the Y-type molecular sieve with reduced unit cell constant is 2.447-2.458 nm, and the water content of the Y-type molecular sieve with reduced unit cell constant is not more than 1 wt%.

[0025] According to one embodiment of the present application, in step (4), the weight ratio of silicon tetrachloride to the Y-type molecular sieve with reduced unit cell constant on a dry basis is 0.1-0.85:1, the reaction temperature is 200°C-600°C, and the reaction time is 10 minutes to 5 hours.

[0026] According to one embodiment of the present application, in step (5), the contacting is arranged to first contact the Y-type molecular sieve with a solution of an inorganic acid with a medium strength or above, and then with a solution of an organic acid.

[0027] According to one embodiment of the present application, the inorganic acid with a medium strength or above is selected from one or more of the following: phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

[0028] According to one embodiment of the present application, the organic acid is selected from one or more of the following: oxalic acid, malonic acid, succinic acid, methyl succinic acid, malic acid, tartaric acid, citric acid, salicylic acid.

[0029] According to one embodiment of the present application, wherein the contacting is for a time of 60 minutes or more, preferably 1-4 hours; at a temperature of 80-99°C; and the weight ratio of the inorganic acid with a medium strength or above to the molecular sieve is 0.001-0.05:1, the weight ratio of the organic acid to the molecular sieve is 0.02-0.10:1, and the weight ratio of water to the molecular sieve is 5-20:1.

[0030] The present application also relates to the use of the modified Y-type molecular sieve described herein for heavy oil catalytic cracking or hydrocracking. DETAILED DESCRIPTION

[0031] In the present application, the weight of various molecular sieves involved, whether explicitly mentioned or not, is based on the dry basis; the weight or content of rare earth salt, rare earth or sodium is based on the weight or content of rare earth oxide; the framework silica-alumina ratio is based on the molar ratio of SiO2 / Al2O3; and the water vapor is based on the volume ratio.

[0032] In the present application, "heavy oil" refers to the remaining heavy oil after the extraction of gasoline and diesel from crude oil, which is characterized by high molecular weight and high viscosity. Examples of heavy oil include, but are not limited to, one or more of atmospheric wax oil, vacuum wax oil, coking wax oil, atmospheric residue, vacuum residue, and heavy cycle oil (HCO).

[0033] In the present application, "catalytic cracking" is one of the petroleum refining processes, which is a process in which heavy oil is converted into cracked gas, gasoline and diesel, etc. under the action of heat and catalyst.

[0034] In the present application, "hydrocracking" is one of the petroleum refining processes, which is a process in which heavy oil is converted into gas, gasoline, jet fuel, diesel, etc. under the action of heat, high hydrogen pressure and catalyst.

[0035] One object of the present application is to provide a modified Y-type molecular sieve rich in secondary pores, wherein the rare earth content of the modified Y-type molecular sieve is 0.5-9 wt% based on the total weight of the Y-type molecular sieve on a dry basis, the sodium content of the modified Y-type molecular sieve is not more than 0.3 wt% based on sodium oxide, and the framework silica-alumina ratio of the modified Y-type molecular sieve is 11-47, preferably 12-38, based on the molar ratio of SiO2 / Al2O3; the modified Y-type molecular sieve is rich in secondary pores, the pore size of the secondary pores is 2-100 nm, the percentage of the pore volume of the secondary pores to the total pore volume is 35-50%, preferably 36-46%, and the specific surface area of the modified Y-type molecular sieve is not less than 675 m 2 / g, preferably 675-695 m 2 / g; the relative crystallinity of the modified Y-type molecular sieve is not less than 75%, preferably 76-83%, and the lattice collapse temperature of the modified Y-type molecular sieve is not less than 1080°C, preferably 1080°C-1100°C.

[0036] Another object of the present application is to provide a method for preparing the modified Y-type molecular sieve rich in secondary pores as described above, which comprises the following steps:

[0037] (1) contacting NaY molecular sieve with NaY mother liquor, adding dilute aqueous acid, and optionally stirring and filtering;

[0038] (2) contacting the NaY molecular sieve obtained in step (1) with a rare earth salt solution to perform an ion exchange reaction, and optionally filtering and washing to obtain a Y-type molecular sieve containing rare earth elements with reduced sodium oxide content;

[0039] (3) subjecting the Y-type molecular sieve containing rare earth elements with reduced sodium oxide content to a mild hydrothermal ultrastable modification treatment, and optionally drying to obtain a Y-type molecular sieve with reduced unit cell constant;

[0040] (4) contacting the Y-type molecular sieve with reduced unit cell constant with silicon tetrachloride gas to perform a reaction, and optionally washing and filtering to obtain an ultrastable modified Y-type molecular sieve;

[0041] (5) contacting the gas-phase ultrastable modified Y-type molecular sieve obtained in step (4) with an acid solution to perform a pore cleaning modification.

[0042] According to one embodiment of the present application, step (1) comprises contacting the NaY molecular sieve filter cake with a NaY mother liquor under stirring, heating to 50-75°C, and slowly adding a dilute aqueous acid solution, and then continuing to stir for 30-60 minutes before filtering.

[0043] According to one embodiment of the present application, the dilute aqueous acid solution in step (1) is dilute hydrochloric acid or dilute sulfuric acid or dilute nitric acid, and the concentration of the dilute aqueous acid solution is 0.001-0.1 mol / L in terms of the molar concentration of H + in the solution; preferably 0.005-0.05 mol / L.

[0044] According to one embodiment of the present application, the volume of the dilute aqueous acid solution in step (1) : the volume of the NaY mother liquor = (0.5-1.5) : 1.

[0045] According to one embodiment of the present application, the ratio of the NaY mother liquor to the NaY molecular sieve is 1-1.9 mL of the NaY mother liquor : 1 g of the NaY molecular sieve.

[0046] According to one embodiment of the present application, the NaY mother liquor in step (1) is from a NaY zeolite synthesis process and is a byproduct of the NaY zeolite synthesis process.

[0047] According to one embodiment of the present application, the NaY mother liquor in step (1) is from Sinopec Catalyst Qilu Branch Company and is the mother liquor remaining after the solid NaY in the NaY synthesis slurry is filtered and separated. In one embodiment, the NaY mother liquor to be recovered contains about 25-40 g / L of SiO2.

[0048] In one embodiment, in step (1) of preparing the modified Y-type molecular sieve, the purpose of adding the dilute aqueous acid solution is to neutralize the basic soluble substances in the NaY mother liquor, change the pH value of the NaY mother liquor, and then make the free soluble Si in the NaY mother liquor uniformly form solid Si in the NaY molecular sieve, so as to provide sufficient Si source accessible to the de-aluminated vacancy for the subsequent hydrothermal ultra-stable process of the molecular sieve, and to maximize the protection of the crystallinity of the molecular sieve from damage in the hydrothermal ultra-stable process.

[0049] In one embodiment, the concentration of the dilute aqueous acid solution in step (1) is 0.001 to 0.1 mol / L in terms of the molar concentration of H + ; preferably 0.005 to 0.05 mol / L; and the volume of the dilute aqueous acid solution can be adjusted to completely precipitate the free soluble Si in the NaY mother liquor into solid Si uniformly in the NaY molecular sieve.

[0050] According to one embodiment of the present application, in step (2), the rare earth salt solution is an aqueous solution of a rare earth salt; and preferably, the rare earth salt is a rare earth chloride and / or a rare earth nitrate; the rare earth content in the Y-type molecular sieve containing a reduced content of sodium oxide and containing a rare earth element is 6.5 to 14 wt% in terms of RE2O3, wherein RE represents a rare earth element; the sodium oxide content is 4 to 8 wt%, for example 4.5 to 7.5 wt%, and the unit cell constant is 2.465 nm to 2.472 nm.

[0051] According to one embodiment of the present application, in step (2), the NaY molecular sieve is subjected to ion exchange with the rare earth solution, and the exchange temperature is preferably 15 to 95°C, for example 20 to 65°C or 65 to 95°C, and the exchange time is preferably 30 to 120 minutes, for example 45 to 90 minutes.

[0052] In one embodiment, in step (2), the NaY molecular sieve (on a dry basis): rare earth salt (in terms of RE2O3): H2O = 1:0.01 to 0.18:5 to 20 by weight.

[0053] In one embodiment, the ion exchange of the NaY molecular sieve with a rare earth salt solution comprises forming a mixture of the NaY molecular sieve (also referred to as NaY zeolite), a rare earth salt and water in a weight ratio of NaY molecular sieve (dry basis): rare earth salt (as RE2O3): H2O = 1 : 0.01 to 0.18 : 5 to 15, stirring at 15 to 95 °C, such as room temperature to 60 °C or 20 to 60 °C or 30 to 45 °C or 65 to 95 °C, preferably for 30 to 120 minutes to exchange the rare earth ions for sodium ions. In one embodiment, the weight ratio of NaY molecular sieve to water is 1 : 6 to 20, preferably 7 to 15. The mixture of NaY molecular sieve, rare earth salt and water can be formed by slurrying the NaY molecular sieve with water and then adding the rare earth salt and / or an aqueous solution of the rare earth salt to the slurry. The rare earth salt is preferably a rare earth chloride and / or a rare earth nitrate. The rare earth is, for example, one or more of La, Ce, Pr, Nd and mixed rare earths, preferably the mixed rare earths contain one or more of La, Ce, Pr and Nd, or also at least one rare earth other than La, Ce, Pr and Nd. The washing in step (2) is to remove the exchanged sodium ions, for example, the washing can be with deionized water or de- cationic water. Preferably, the rare earth content of the reduced sodium oxide content rare earth containing conventional unit cell size Y-type molecular sieve obtained in step (2) is 6.5 to 14 wt% RE2O3, such as 7 to 14 wt% or 7.5 to 13 wt%, and the sodium oxide content is no more than 8 wt%, such as 4.5 to 7.5 wt%, and the unit cell constant is 2.465 nm to 2.472 nm.

[0054] In one embodiment, in step (3), the mild hydrothermal USY modification treatment comprises calcining the Y-type molecular sieve at a temperature of 350 to 550 °C in an atmosphere containing 40 to 95 vol% water vapor for 4.5 to 7 hours; and optionally drying.

[0055] In one embodiment, in step (3), the unit cell constant of the unit cell constant reduced Y-type molecular sieve is 2.447 to 2.458 nm, and the water content of the unit cell constant reduced Y-type molecular sieve is no more than 1 wt%.

[0056] In one embodiment, in step (4), the weight ratio of silicon tetrachloride to the unit cell constant reduced Y-type molecular sieve (dry basis) is 0.1 to 0.85 : 1, the reaction temperature is 200 °C to 600 °C, and the reaction time is 10 minutes to 5 hours.

[0057] In one embodiment, step (4) can be washed or not washed, and after washing, the washing can be dried or not dried. The washing can be by a conventional washing method, such as with water, for example de- cationic water or deionized water, to remove residual Na from the zeolite.+ Cl - and Al 3+ Soluble byproducts, such as those from the washing process, can be removed under the following conditions: a weight ratio of washing water to molecular sieve of 5–20:1, a molecular sieve to H₂O weight ratio of 1:6–15, a pH value preferably of 2.5–5.0, and a washing temperature of 30–60°C. Typically, the washing process continues until no free Na₂O is detectable in the resulting solution. + Cl - and Al 3+ Plasma, typically Na in washed molecular sieve samples + Cl - and Al 3+ The content of each ion is no more than 0.05% by weight.

[0058] In one embodiment, in step (5), the pore cleaning modification is performed in two steps, including first contacting the Y-type molecular sieve with an inorganic acid solution of moderate to strong strength, and then contacting it with an organic acid solution. After a period of contact reaction, the reacted molecular sieve is separated from the acid solution, for example by filtration, and then optionally washed to remove residual Na from the zeolite. + Cl - and Al 3+ Soluble byproducts are then optionally dried.

[0059] In one embodiment, in step (5), the inorganic acid of moderate strength or higher is selected from one or more of the following: phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

[0060] In one embodiment, in step (5), the organic acid is selected from one or more of the following: oxalic acid, malonic acid, succinic acid, methylsuccinic acid, malic acid, tartaric acid, citric acid, and salicylic acid.

[0061] In one embodiment, in step (5), the contact time is 60 minutes or more, preferably 1 to 4 hours; the contact temperature is 80 to 99°C; and the weight ratio of inorganic acid of medium strength or above to molecular sieve is 0.001 to 0.05:1, the weight ratio of organic acid to molecular sieve is 0.02 to 0.10:1, and the weight ratio of water to molecular sieve is 5 to 20:1.

[0062] In one embodiment, after aging for 17 hours at 800°C, atmospheric pressure, and a 100% water vapor atmosphere, the relative crystallinity retention of the modified Y-type molecular sieve is 50% or more, for example, 55-65%. In this application, "atmospheric pressure" refers to 1 atm.

[0063] According to the method of the present application, especially by recycling the NaY mother liquor to be recycled for the preparation process of the molecular sieve, the recovery rate of the NaY mother liquor is significantly improved. Compared with the prior art, according to the method of the present application, the recovery rate of the NaY mother liquor can be as high as 89.2% or even 95.2%.

[0064] In addition, the method of the present application significantly improves the crystallinity of the Y-type molecular sieve, and significantly improves the framework silica-alumina ratio of the molecular sieve, so that the lattice collapse temperature of the obtained Y-type molecular sieve is significantly improved.

[0065] In one embodiment, the lattice collapse temperature of the modified Y-type molecular sieve is not less than 1080°C, preferably 1080°C to 1100°C, for example 1083°C, 1087°C, 1090°C or 1096°C, indicating that it has high thermal stability.

[0066] Without being limited by any theory, the inventors of the present application believe that the ultrastable process of the conventional hydrothermal ultrastable method is to use water molecules to attack aluminum atoms on the molecular sieve framework at high temperature, so that Al atoms are removed from the molecular sieve framework to generate Al(OH)3, and after the Al atoms on the framework are removed, Al vacancies are left, then free Si in the molecular sieve migrates to the Al vacancies and fills into the vacancies to complete the dealumination and silicon supplementation process, and the framework silica-alumina ratio is increased, and the molecular sieve structure is ultrastabilized. However, the problem in the conventional hydrothermal ultrastabilization is that the speed of dealumination of the molecular sieve is much greater than the speed of silicon migration, and since the silicon source near the aluminum of the molecular sieve framework is small, the vacancies generated after the aluminum on the framework is removed by water vapor cannot be timely supplemented by silicon migration, resulting in lattice collapse and thus loss of crystallinity of the molecular sieve, and therefore it is difficult to produce a hydrothermal ultrastable molecular sieve with high crystallinity and high silica-alumina ratio.

[0067] In comparison, in the method of the present application, firstly, in step (1), the silicon source is introduced by recovering the NaY mother liquor, so that the free soluble Si in the NaY mother liquor uniformly forms solid Si in the NaY molecular sieve, providing sufficient Si source accessible to migrate to the dealuminated vacancy in the subsequent hydrothermal ultrastable process, so as to maximize the protection of the crystallinity of the molecular sieve from damage in the hydrothermal ultrastable process. Secondly, in step (3), by controlling the hydrothermal ultrastable conditions, including controlling the temperature to be 350-550°C, controlling the water vapor atmosphere to contain 40-95% by volume of water vapor, and controlling the calcination time to be 4.5-7 hours, the mild hydrothermal ultrastable process is realized, and the molecular sieve maintains a relatively high crystallinity in the hydrothermal ultrastable process. Thirdly, on the basis that the molecular sieve still maintains a relatively high crystallinity after the hydrothermal ultrastable process, in step (4), by contacting the silicon tetrachloride gas with the molecular sieve at a relatively high temperature, a dealumination and silicon supplementation reaction occurs with Al in the framework structure of the molecular sieve, and then the framework silicon to aluminum ratio of the molecular sieve can be further increased while the molecular sieve maintains a relatively high crystallinity. The organic combination of steps (1) and (3) and (4) realizes the relay dealumination and silicon supplementation of the molecular sieve under the condition of maintaining a relatively high crystallinity, so that the Y-type molecular sieve obtained by the present application has a relative crystallinity of not less than 75%, a relative crystallinity retention of not less than 55%, a framework silicon to aluminum ratio as high as 11-47, preferably 12-38, a structure collapse temperature as high as 1080°C, and even as high as 1096°C.

[0068] In addition, according to the method of the present application, the prepared molecular sieve can have a uniform aluminum distribution, a low non-framework aluminum content, a high secondary pore content, unobstructed secondary pore channels, and a high specific surface area with a high proportion of secondary pores.

[0069] The modified Y-type molecular sieve rich in secondary pores prepared by the method of the present application can be used to prepare a catalyst for the catalytic cracking of heavy oil. The obtained catalyst has a high light oil yield, a high liquid yield, a low coke selectivity, and an increased gasoline yield, and a higher heavy oil conversion activity.

[0070] The modified Y-type molecular sieve rich in secondary pores prepared by the method of the present application can be used to prepare a catalyst for the hydrocracking of heavy oil; the hydrocracking catalyst with the molecular sieve as the acidic component has a high hydrogenation activity (toluene conversion rate) and a high hydrocracking activity (n-decane conversion rate).

[0071] The modified Y-type molecular sieve of the present application and its preparation and application will be described in detail below in conjunction with specific examples, but it should be understood that the specific examples given are only for illustration and do not limit the present application in any way.

[0072] Examples

[0073] Raw materials

[0074] In the examples and comparative examples, the NaY molecular sieve (also referred to as NaY zeolite) used was provided by Qilu Branch of Sinopec Catalyst Co., Ltd., with a sodium oxide content of 13.5 wt%, a framework silica-alumina ratio (molar ratio of SiO2 / Al2O3) = 4.6, a unit cell constant of 2.470 nm, and a relative crystallinity of 90%; the NaY mother liquor was provided by Qilu Branch of Sinopec Catalyst Co., Ltd., and was a mother liquor discharged after the solid NaY was separated by filtration from the NaY synthesis slurry, which contained a silicon source that failed to be recycled to the NaY molecular sieve synthesis process, with the silicon source being about 30 g / L in terms of SiO2 mass concentration; it is also known in the prior art that the Si recovery rate in the NaY mother liquor is 62-75%; the chlorinated rare earth and the nitric rare earth were chemical pure reagents produced by Beijing Chemical Plant; the pseudoboehmite was an industrial product produced by Shandong Aluminum Factory, with a solid content of 61 wt%; the kaolin was a cracking catalyst special kaolin produced by Suzhou China Kaolin Co., Ltd., with a solid content of 76 wt%; the aluminum sol was provided by Qilu Branch of Sinopec Catalyst Co., Ltd., and had an alumina content of 21 wt%. The raw oil Wuhan mix three-2007 was purchased from Sinopec Wuhan Branch. The chemical reagents used in the examples and comparative examples were of chemical purity unless otherwise specified.

[0075] Analytical method

[0076] In each of the examples and comparative examples, the elemental content of the Y-type molecular sieve was determined by X-ray fluorescence spectroscopy; the unit cell constant and the relative crystallinity of the Y-type molecular sieve were determined by X-ray powder diffraction (XRD) according to the standard methods of RIPP 145-90 and RIPP 146-90 (see Petroleum Chemical Industry Analysis Methods (RIPP Test Methods) edited by Yang Cuiding et al., published by Science Press in 1990); the total silica-alumina ratio of the Y-type molecular sieve was calculated based on the Si and Al elemental contents determined by X-ray fluorescence spectroscopy; the framework silica-alumina ratio of the NaY molecular sieve was calculated according to the following formula: SiO2 / Al2O3 molar ratio = 2 x (2.5858 - a0) / (a0 - 2.4191), wherein a0 is the unit cell constant in nm; the crystal structure collapse temperature was determined by differential thermal analysis (DTA).

[0077] In each of the examples and comparative examples, the total pore volume of the molecular sieve was determined according to the adsorption isotherm according to the standard method of RIPP 151-90 (Petroleum Chemical Industry Analysis Methods (RIPP Test Methods) edited by Yang Cuiding et al., published by Science Press in 1990), and then the micropore volume of the molecular sieve was determined from the adsorption isotherm according to the T plotting method, and the secondary pore volume was obtained by subtracting the micropore volume from the total pore volume.

[0078] In each of the examples, the calculation method of the Si recovery rate in the NaY mother liquor was as follows:

[0079] In the synthesis of NaY molecular sieve, the total amount of NaY mother liquor produced is about 7.64 mL per 1 g of NaY molecular sieve, and it is known that about 62% to 75% of Si in the mother liquor can be recycled in the existing NaY synthesis process.

[0080] The total Si recovery rate of the NaY mother liquor according to the present application = the Si recovery rate of the NaY mother liquor in the existing NaY synthesis process + the additional Si recovery rate of the NaY mother liquor according to the method of the present application

[0081] The Si recovery rate of the NaY mother liquor in the existing NaY synthesis process is about 75%

[0082] The additional Si recovery rate of the NaY mother liquor according to the method of the present application = the Si recovery amount (mL) of the NaY mother liquor according to the method of the present application / the dry basis weight (g) of the NaY mother liquor / 7.64 (mL / g)

[0083] The total Si recovery rate of the NaY mother liquor according to the method of the present application = the additional Si recovery amount (mL) of the NaY mother liquor according to the method of the present application / the dry basis weight (g) of the NaY mother liquor / 7.64 (mL / g) + the Si recovery rate of the NaY mother liquor in the existing NaY synthesis process.

[0084] Example 1

[0085] 200 kg (dry basis weight) of NaY zeolite filter cake (solid content 46%, sodium oxide content 13.5 wt%, industrial product of SINOPEC Catalyst Qilu Branch) was added to an exchange tank containing 217 L of NaY mother liquor (the NaY mother liquor was the remaining mother liquor after the solid NaY was separated by filtration from the NaY synthesis slurry of SINOPEC Catalyst Qilu Branch, and the SiO2 mass concentration was 30 g / L) under stirring, and the temperature was raised to 50°C under stirring, then 217 L of dilute nitric acid with a molar concentration of 0.01 mol / L was slowly added, and after stirring for 30 minutes, filtration was performed. Then, 2 m + L of 10% sodium carbonate solution was added, and the temperature was raised to 50°C under stirring, then 217 L of dilute nitric acid with a molar concentration of 0.01 mol / L was slowly added, and after stirring for 30 minutes, filtration was performed. Then, 2 m 3The water in the primary exchange tank was stirred at 25°C until uniform, then 63.2 L of the RECl3 solution (the rare earth concentration in the RECl3 solution was 312 g / L as RE2O3, and RE2O3 contained 64.5% Ce2O3 and 35.5% La2O3) was added, and stirring was continued for 60 min, then the mixture was filtered and washed, and the filter cake was sent to a flash drying oven for drying; then, the mixture was sent to a calcination furnace for calcination at a temperature of 410°C under an atmosphere containing 65% water vapor for 6 h; then, the mixture was calcined at a temperature of 500°C under a dry air atmosphere for 2.5 h to reduce the water content to less than 1% by weight, thereby obtaining Y-type molecular sieve with a reduced unit cell constant, and the unit cell constant of the Y-type molecular sieve was 2.456 nm; then, the Y-type molecular sieve was subjected to a gas phase ultrastabilization reaction, and the process conditions for the gas phase ultrastabilization reaction were as follows: the weight ratio of SiCl4 to Y-type zeolite was 0.5:1, and the reaction temperature was 485°C, and the reaction time was 1.5 h. After the gas phase ultrastabilization reaction, the molecular sieve material was separated by a gas-solid separator and was then sent to a secondary exchange tank, and 2 m 3 of water was added to the secondary exchange tank in advance, and the weight of the molecular sieve material added to the secondary exchange tank was 200 kg (dry basis), and the mixture was stirred until uniform, then 60 L of 10% by weight hydrochloric acid was added, and the temperature was raised to 90°C, and stirring was continued for 60 min, then 14 kg of citric acid was added, and stirring was continued at 90°C for 60 min, then the mixture was filtered and washed, and was dried to obtain a modified Y-type molecular sieve (molecular sieve is also referred to as zeolite) product, which is referred to as SZ-1. Table 1 shows the composition, unit cell constant, relative crystallinity, framework silica-alumina ratio, structure collapse temperature, specific surface area, and percentage of secondary pores with a pore size of 8 nm to 100 nm relative to the total secondary pores (2 nm to 100 nm), and total secondary pore volume of the SZ-1.

[0086] After the SZ-1 was aged at 800°C, 1 atm, and 100% water vapor for 17 h in a naked state, the relative crystallinity of the molecular sieve before and after aging was analyzed by XRD, and the relative crystallinity retention after aging was calculated, and the results are shown in Table 2, wherein:

[0087]

[0088] Example 2

[0089] The filter cake of 200 kg (dry basis) of NaY zeolite (solid content was 46%, and the sodium oxide content was 13.5% by weight, and the product was an industrial product of SINOPEC Catalyst Qilu Branch) was added to an exchange tank containing 257 L of NaY mother liquor (the NaY mother liquor was the mother liquor remaining after the solid NaY was separated from the NaY synthesis slurry of SINOPEC Catalyst Qilu Branch, and the SiO2 mass concentration was 30 g / L) while stirring, and the temperature was raised to 80°C, then H +dilute hydrochloric acid of 0.012 mol / L 215 L, then, continue stirring for 50 minutes, and filter. Then, add into the primary exchange tank with 2 m 3 water, stir well, then add 85.2 L RECl3 solution (the rare earth concentration in the RECl3 solution is 312 g / L in terms of RE2O3, and RE2O3 contains 64.5% Ce2O3 and 35.5% La2O3), stir for 60 minutes; filter, wash, and dry the filter cake in a flash drying oven to obtain the rare earth-containing conventional cell size Y-type molecular sieve with reduced sodium oxide content, the sodium oxide content of which is 5.5% by weight, and the cell constant is 2.471 nm; then, send it into the calcination furnace to be calcined at a temperature (atmosphere temperature) of 490°C for 5.5 hours in a 80% water vapor atmosphere; then, the molecular sieve material is sent into the calcination furnace for calcination drying treatment, the calcination temperature is 500°C, the atmosphere is dry air atmosphere, and the calcination time is 2 hours, so that the water content is less than 1% by weight, to obtain the Y-type molecular sieve with reduced cell constant, the cell constant of which is 2.455 nm; then, directly send the Y-type molecular sieve material with reduced cell constant into the gas phase ultrastable reactor for gas phase ultrastable reaction, the process conditions are: the weight ratio of SiCl4 to Y-type zeolite is 0.25:1, the reaction temperature is 500°C, and the reaction time is 50 minutes. After the gas phase ultrastable reaction, the molecular sieve material is separated by a gas-solid separator and then sent into the secondary exchange tank, the secondary exchange tank is previously added with 2 m 3 of water, the weight of the molecular sieve material added into the secondary exchange tank is 200 Kg (dry basis), stir well, then add 0.09 m 3 of sulfuric acid solution with a concentration of 7% by weight, and heat to 93°C, stir for 80 minutes, then add 7 Kg of citric acid and 5 Kg of tartaric acid, continue stirring at 93°C for 70 minutes, then filter, wash, and dry to obtain the modified Y-type molecular sieve product, which is recorded as SZ-2. Table 1 shows the composition, cell constant, relative crystallinity, framework silica-alumina ratio, structure collapse temperature, specific surface area, and the percentage of secondary pores with a larger pore size (pore size of 8-100 nm) in the total secondary pores (2-100 nm), and the total secondary pore volume of SZ-2.

[0090] Then filter, dry, and obtain the modified Y-type molecular sieve product, which is recorded as SZ-2. Table 1 shows the composition, cell constant, relative crystallinity, framework silica-alumina ratio, structure collapse temperature, specific surface area, and the percentage of secondary pores with a larger pore size (pore size of 8-100 nm) in the total secondary pores (2-100 nm), and the total secondary pore volume of SZ-2.

[0091] After aging SZ-2 in a naked state at 800°C for 17 hours in a 100% water vapor atmosphere, the crystallinity of the zeolite before and after aging of SZ-2 was analyzed by XRD, and the relative crystallinity retention after aging was calculated, and the results are shown in Table 2.

[0092] Example 3

[0093] A 200 kg (dry basis) NaY zeolite filter cake (solid content 46%, sodium oxide content 13.5 wt%, industrial product of SINOPEC Qilu Catalyst Branch Company) was added to an exchange tank containing 302 L of NaY mother liquor (NaY mother liquor is the mother liquor remaining after the solid NaY is separated from the NaY synthesis slurry of SINOPEC Qilu Catalyst Branch Company, and the SiO2 mass concentration is 30 g / L) under stirring, and heated to 80°C under stirring, then H + 336 L of dilute sulfuric acid with a molar concentration of 0.009 mol / L was slowly added, and after 50 minutes of continuous stirring, filtration was performed. Then, the filter cake was added to a first exchange tank containing 2 m 3 L of water, and stirred uniformly at 90°C, then 69.5 L of RECl3 solution (the rare earth concentration in the RECl3 solution is 312 g / L as RE2O3, and the RE2O3 contains 64.5% Ce2O3 and 35.5% La2O3) was added, and after 60 minutes of continuous stirring, filtration, washing, and drying of the filter cake in a flash dryer, a conventional cell size Y-type molecular sieve containing rare earth with a reduced sodium oxide content was obtained, and the sodium oxide content was 7.5 wt%, and the cell constant was 2.471 nm; then, the Y-type molecular sieve was sent to a calcination furnace and calcined at a calcination temperature of 470°C under a 75 vol% water vapor atmosphere for 5 hours; then, the Y-type molecular sieve was sent to a calcination furnace for calcination drying treatment, and the calcination temperature was 520°C, the calcination atmosphere was dry air, and the calcination time was 1.5 hours, so that the water content was less than 1 wt%, and a Y-type molecular sieve with a reduced cell constant was obtained, and the cell constant was 2.457 nm; then, the Y-type molecular sieve with a reduced cell constant was sent to a gas phase ultrastable reactor for gas phase ultrastable reaction. The process conditions were as follows: the weight ratio of SiCl4 to Y-type zeolite was 0.45:1, the reaction temperature was 510°C, and the reaction time was 2 hours. After the gas phase ultrastable reaction, the molecular sieve material was separated by a gas-solid separator and sent to a second exchange tank, and 20 m 3 L of deionized water was previously added to the second exchange tank, and the weight of the molecular sieve material added to the second exchange tank was 200 kg (dry basis), and the mixture was stirred uniformly, then 0.12 m 3and the temperature was raised to 95°C and stirring was continued for 90 minutes. Then, 9 Kg of citric acid and 4 Kg of oxalic acid were added and stirring was continued at 93°C for 70 minutes. After filtration and washing, a sample was dried and was designated as SZ-3. The composition, unit cell constant, relative crystallinity, framework silica to alumina ratio, structure collapse temperature, specific surface area, and percentage of secondary pores having a large pore size (pore size of 80-100 nm) to the total secondary pores (2-100 nm) and total secondary pore volume of SZ-3 are given in Table 1. After aging of SZ-3 in the naked state at 800°C for 17 hours under 100% steam, the crystallinity of the zeolite of SZ-3 before and after aging was analyzed by XRD and the relative crystallinity retention after aging was calculated, and the results are given in Table 2.

[0094] Comparative Example 1

[0095] Two thousand grams of NaY zeolite (dry basis) were added to 20 liters of de- cationized water and stirred to mix uniformly. Then, 1000 grams of (NH4)2SO4 were added and stirred. The temperature was raised to 90-95°C and maintained for 1 hour. After filtration and washing, the filter cake was dried at 120°C and then subjected to hydrothermal modification treatment (calcination at 650°C under 100% steam for 5 hours). After that, the product was added to 20 liters of de-cationized water and stirred to mix uniformly. Then, 1000 grams of (NH4)2SO4 were added and stirred. The temperature was raised to 90-95°C and maintained for 1 hour. After filtration and washing, the filter cake was dried at 120°C and then subjected to second hydrothermal modification treatment (calcination at 650°C under 100% steam for 5 hours). Thus, a rare earth-free hydrothermally stabilized Y-type zeolite which was subjected to ion exchange twice and hydrothermal stabilization twice was obtained and was designated as DZ-1. The composition, unit cell constant, relative crystallinity, framework silica to alumina ratio, structure collapse temperature, specific surface area, and percentage of secondary pores having a large pore size (pore size of 80-100 nm) to the total secondary pores (2-100 nm) and total secondary pore volume of DZ-1 are given in Table 1. After aging of DZ-1 in the naked state at 800°C for 17 hours under 100% steam, the crystallinity of the zeolite of DZ-1 before and after aging was analyzed by XRD and the relative crystallinity retention after aging was calculated, and the results are given in Table 2.

[0096] In this comparative example, the NaY mother liquor involved in the preparation of NaY zeolite was recovered by a method known in the art and the recovery rate was 62.5%.

[0097] Comparative Example 2

[0098] Take 2000 grams of NaY molecular sieve (dry base) into 20 liters of de-cationic water solution, stir to mix evenly, add 1000 grams of (NH4)2SO4, stir, heat to 90-95°C for 1 hour, then filter, wash, and after drying the filter cake at 120°C, proceed with hydrothermal modification treatment, the conditions of hydrothermal modification treatment: temperature 650°C, 100% water vapor for 5 hours, then add to 20 liters of de-cationic water solution, stir to mix evenly, add 200 ml of RE(NO3)3 solution (rare earth solution concentration: 319 g / L of RE2O3), and 900 grams of (NH4)2SO4, stir, heat to 90-95°C for 1 hour, then filter, wash, and after drying the filter cake at 120°C, proceed with second hydrothermal modification treatment (temperature 650°C, 100% water vapor for 5 hours), to obtain a rare earth-containing hydrothermally stabilized Y-type molecular sieve which has been ion exchanged twice and hydrothermally stabilized twice, denoted as DZ-2. Table 1 gives the composition, unit cell constant, relative crystallinity, framework silica-alumina ratio, structure collapse temperature, specific surface area, and percentage of secondary pores with a larger pore size (pore size 8-100 nm) to the total secondary pores (2-100 nm), and total secondary pore volume of DZ-2. DZ-2 was aged at 800°C for 17 hours in 100% water vapor in a naked state, and the crystallinity of the zeolite before and after aging of DZ-2 was analyzed by XRD, and the relative crystallinity retention after aging was calculated, and the results are shown in Table 2.

[0099] In this comparative example, the NaY mother liquor involved in the preparation of NaY molecular sieve was recovered by a method known in the prior art, and the recovery rate was 65%.

[0100] Comparative Example 3

[0101] Take 2000 kilograms of NaY molecular sieve (dry base) into 20 m 3 Stir to mix evenly, add 650 liters of RE(NO3)3 solution (319 g / L), stir, heat to 90-95°C for 1 hour, then filter, wash, and continuously send the filter cake to a flash and calcination furnace for calcination and drying treatment, control the calcination temperature at 500°C, the calcination atmosphere is dry air atmosphere, and the calcination time is 2 hours, so that the water content is less than 1 wt%, then send the dried molecular sieve material to a continuous gas phase stabilization reactor for gas phase stabilization reaction. The gas phase stabilization reaction process of the molecular sieve in the continuous gas phase stabilization reactor and the subsequent tail gas absorption process are carried out according to the method of Example 1 disclosed in CN103787352A patent, and the process conditions are: SiCl4: Y-type zeolite weight ratio = 0.4:1, the feed amount of the molecular sieve is 800 kg / hour, and the reaction temperature is 580°C. After the gas phase stabilization reaction, the molecular sieve material is separated by a gas-solid separator and sent to a secondary exchange tank, 20 m 3water, the weight of the molecular sieve material in the secondary exchange tank was 2000 Kg (dry basis), and the stirring was uniform, then 5 wt% of nitric acid 1.2 m 3 and the temperature was raised to 95°C, the stirring was continued for 90 minutes, then 90 Kg of citric acid and 40 Kg of oxalic acid were added, the stirring was continued at 93°C for 70 minutes, then filtration, washing, drying and sampling, the sample was recorded as DZ-3. Table 1 shows the composition, cell constant, relative crystallinity, framework silica alumina ratio, structure collapse temperature, specific surface area and percentage of secondary pores with larger pore size (pore size 8-100 nm) in total secondary pores (2-100 nm), total secondary pore volume of DZ-3. After DZ-3 was aged at 800°C for 17 hours in 100% water vapor in a naked state, the crystallinity of the zeolite before and after aging was analyzed by XRD method and the relative crystallinity retention after aging was calculated, the results are shown in Table 2.

[0102] In this comparative example, the NaY mother liquor involved in the preparation of NaY zeolite was recovered by a method known in the prior art, and the recovery rate was 75%.

[0103] Comparative Example 4

[0104] 2000 Kg (dry basis) of NaY type zeolite with a framework SiO2 / Al2O3 ratio of 4.6 (sodium oxide content 13.5 wt%, produced by SINOPEC Qilu Catalyst Co., Ltd.) was added to a 20 m 3The de-cationized water in the first exchange tank was stirred at 90°C, then 800 L of RECl3 solution (the concentration of rare earth in the RECl3 solution was 319 g / L as RE2O3) was added, and stirred for 60 minutes. The mixture was filtered and washed, and the filter cake was sent to a flash drying oven for drying to obtain a conventional cell size Y-type molecular sieve containing rare earth with a reduced sodium oxide content, the sodium oxide content was 5.5 wt%, and the cell constant was 2.471 nm. Then, the Y-type molecular sieve was sent to a calcination furnace for calcination at a temperature (atmosphere temperature) of 450°C under an atmosphere of 80% steam for 5.5 hours. Then, the Y-type molecular sieve was sent to a calcination furnace for calcination and drying treatment, the calcination temperature was 500°C, the atmosphere was dry air, and the calcination time was 2 hours, so that the water content was less than 1 wt%, and a Y-type molecular sieve with a reduced cell constant was obtained, the cell constant was 2.461 nm. Then, the Y-type molecular sieve with a reduced cell constant was directly sent to a continuous gas phase ultra-stable reactor for gas phase ultra-stable reaction. The gas phase ultra-stable reaction process of the molecular sieve in the continuous gas phase ultra-stable reactor and the subsequent tail gas absorption process were carried out according to the method of Example 1 of the patent CN103787352A, and the process conditions were as follows: the weight ratio of SiCl4 to Y-type zeolite was 0.25:1, the feeding amount of the molecular sieve was 800 kg / hour, and the reaction temperature was 490°C. After the gas phase ultra-stable reaction, the molecular sieve material was separated by a gas-solid separator and then sent to a second exchange tank. The second exchange tank was pre-filled with 20 m 3 of de-cationized water, and the weight of the molecular sieve material added into the second exchange tank was 2000 Kg (dry basis). After stirring uniformly, 0.9 m 3 of a 7 wt% sulfuric acid solution was added, and the temperature was raised to 93°C. The mixture was stirred for 80 minutes, then 70 Kg of citric acid and 50 Kg of tartaric acid were added. The mixture was continuously stirred at 93°C for 70 minutes, then filtered, washed, and dried to obtain a modified Y-type molecular sieve product, which was denoted as DZ-4. Table 1 shows the composition, cell constant, relative crystallinity, framework silica-alumina ratio, structure collapse temperature, specific surface area, and the percentage of secondary pores with a pore size of 8-100 nm in the total secondary pores (2-100 nm), and the total secondary pore volume of DZ-4. DZ-4 was aged at 800°C for 17 hours under 100% steam in a naked state. The crystallinity of the zeolite before and after aging was analyzed by XRD, and the relative crystallinity retention after aging was calculated. The results are shown in Table 2.

[0105] In this comparative example, the NaY mother liquor involved in the preparation of NaY molecular sieve was recovered by a method known in the prior art, and the recovery rate was 75%.

[0106] Examples 4-6

[0107] The above materials are mixed with water and slurried according to the weight ratio of (dry basis) molecular sieve: kaolin: pseudo-boehmite: aluminum sol = 30:38:22:10, and then spray dried at 450°C to obtain a spherical catalytic cracking catalyst. The modified Y-type molecular sieves SZ-1, SZ-2 and SZ-3 prepared in Examples 1-3 are used respectively to obtain catalysts SC-1, SC-2 and SC-3.

[0108] Comparative Examples 5-8

[0109] The reference catalysts DC-1, DC-2, DC-3 and DC-4 are prepared according to the method of preparing catalytic cracking catalysts and the material ratio of the catalysts of Example 4, using the molecular sieves DZ-1, DZ-2, DZ-3 and DZ-4 prepared in Comparative Examples 1-4.

[0110] Examples 7-9

[0111] Examples 7-9 illustrate the heavy oil catalytic cracking reaction performance of the modified Y-type molecular sieves provided by the present application.

[0112] Comparative Examples 9-12

[0113] Comparative Examples 9-12 illustrate the heavy oil catalytic cracking reaction performance of the catalysts prepared in Comparative Examples 5-8.

[0114] The heavy oil cracking performance evaluation conditions are that the catalyst is first aged at 800°C under 100% steam for 17 hours, and then evaluated on an ACE (fixed fluidized bed) device, with the raw oil being Wuhan mixed three-2007 (properties shown in Table 3), and the reaction temperature being 500°C.

[0115] Wherein, conversion = gasoline yield + liquefied gas yield + dry gas yield + coke yield

[0116] Light oil yield = gasoline yield + diesel yield

[0117] Liquid yield = liquefied gas + gasoline + diesel

[0118] Coke selectivity = coke yield / conversion

[0119] The catalytic cracking performance of the catalysts prepared in Examples 4-6 and Comparative Examples 5-8 is evaluated according to the above method, and the results are shown in Table 4.

[0120] Example 10

[0121] 200 kg (dry weight) of NaY zeolite filter cake (solid content 46%, sodium oxide content 13.5 wt%, industrial product of Sinopec Catalyst Qilu Branch) was added to an exchange tank containing 300 L of NaY mother liquor (the NaY mother liquor is the remaining mother liquor after filtering and separating solid NaY from the NaY synthesis slurry of Sinopec Catalyst Qilu Branch, with a SiO2 mass concentration of 30 g / L). The temperature was raised to 50 °C with stirring, and then H was slowly added. + 300 L of dilute hydrochloric acid with a molar concentration of 0.01 mol / L was added, and then stirred for 30 minutes before filtration. Then, it was added to a container containing 2 mL of... 3 After the water was stirred evenly in a primary water exchange tank at 25°C, 65.1 L of RECl3 solution was added (the rare earth concentration in the RECl3 solution was 312 g / L, calculated as RE2O3, containing 64.5% Ce2O3 and 35.5% La2O3). After stirring for 60 minutes, the mixture was filtered, washed, and the filter cake was sent to a flash drying oven for drying. Then, it was sent to a calcination oven and calcined for 6 hours at 530°C with 90% water vapor (the atmosphere contained 90% by volume water vapor). Then, it was calcined for 2.5 hours at 550°C in a dry air atmosphere to reduce the water content to less than 1% by weight, resulting in a Y-type molecular sieve with a reduced cell constant of 2.448 nm. Then, a gas-phase ultrastable reaction was carried out under the following conditions: SiCl4:Y-type zeolite weight ratio = 0.8:1, reaction temperature of 590°C, and reaction time of 2 hours. After the gas-phase ultrastable reaction, the molecular sieve material is separated by a gas-solid separator and then sent to a secondary exchange tank, which is pre-filled with 2m³ of gas. 3 Water was added to the molecular sieve material in the secondary exchange tank at a weight of 200 kg (dry basis), and the mixture was stirred until homogeneous. Then, 60 L of 10% hydrochloric acid was added, and the temperature was raised to 90 °C. The mixture was stirred for 60 minutes, followed by the addition of 14 kg of citric acid. The mixture was stirred for another 60 minutes at 90 °C, then filtered, washed, and dried to obtain the modified Y-type molecular sieve (also known as zeolite) product, denoted as SZ-10. Table 1 shows the composition of SZ-10, including cell constant, relative crystallinity, framework silica-alumina ratio, structural collapse temperature, specific surface area, percentage of secondary pores with larger pore sizes (8 nm to 100 nm) to total secondary pores (2 to 100 nm), and total secondary pore volume.

[0122] After SZ-10 was aged at 800℃, 1 atm, and 100% water vapor for 17 hours in an exposed state, the relative crystallinity of the molecular sieve before and after aging was analyzed by XRD and the relative crystallinity retention after aging was calculated. The results are shown in Table 2.

[0123] Comparative Example 13

[0124] The present comparative example is a preparation method of a modified Y molecular sieve of an acidic component in a hydrocracking catalyst in the prior art.

[0125] (1) 100 g (dry basis) of NaY molecular sieve (produced by Qilu Catalyst Branch Company of Sinopec, cell constant: 2.466 nm, relative crystallinity: 90.2%, Na2O content: 13.5, SiO2 / Al2O3 molar ratio: 5.11) was dispersed in 1300 mL of water, and 100 mL of an aqueous solution containing 45 g of ammonium nitrate (purchased from Beijing Yili Chemical Reagent Factory) was added at a constant speed under stirring at 35°C (the dropwise addition time was controlled to be 40 min). After the aqueous solution was added, the stirring was stopped and the mixture was filtered. The solid phase was washed with deionized water for 3 times and then dried at 110°C in an air atmosphere under normal pressure for 3.5 h, thereby obtaining the exchanged molecular sieve.

[0126] (2) 85 g (dry basis) of the exchanged molecular sieve prepared in step (1) was placed in a tube furnace, water vapor was continuously introduced into the tube furnace (the introduction rate of water vapor was 0.30 mL / (min.g of molecular sieve)), and the temperature in the tube furnace was maintained at 600°C for 2.5 h of hydrothermal treatment. After natural cooling to ambient temperature, the first hydrothermally treated molecular sieve was obtained.

[0127] (3) 80 g (dry basis) of the first hydrothermally treated molecular sieve was dispersed in 1000 mL of distilled water, and 150 mL of an aqueous solution containing 60 g of ammonium sulfate and 10 g of sulfuric acid was added at a constant speed under stirring at 35°C (the dropwise addition time was controlled to be 45 min). After the addition was completed, the stirring was continued for 60 min. Then, the mixture was filtered, the solid phase was washed with deionized water for 2 times, and then dried at 110°C in an air atmosphere under normal pressure for 3 h, thereby obtaining the dealuminated molecular sieve.

[0128] (4) 60 g (dry basis) of the molecular sieve obtained in step (3) was placed in a tube furnace, a mixture of water vapor and air was continuously introduced into the tube furnace (the introduction rate of water vapor was 0.3 mL / (min.g of molecular sieve), and the introduction amount of air was 15 L / (min.g of molecular sieve)), and the temperature in the tube furnace was maintained at 620°C for 3 h of hydrothermal treatment. After the hydrothermal treatment was completed, the second hydrothermally treated molecular sieve was obtained after natural cooling to ambient temperature.

[0129] (5) 60 g (dry basis) of the second hydrothermally treated molecular sieve prepared in step (4) was dispersed in 650 mL of distilled water, and the mixture was heated to 60°C with stirring, and 100 mL of an aqueous solution containing 25 g of ammonium chloride and 15 g of fluosilicic acid was added dropwise at a uniform rate (the dropwise addition was controlled to take 25 min). After the dropwise addition was completed, stirring was continued for 30 min. After the temperature naturally decreased to ambient temperature, the mixture was filtered, the solid phase was washed twice with deionized water, and then dried at 110°C under an air atmosphere at normal pressure for 3 h, thereby obtaining a dealuminized Y-type molecular sieve.

[0130] (6) 5 g of nickel nitrate and 20 g of ammonium heptamolybdate were dissolved in 100 mL of water, and 25 wt% concentrated ammonia water was added dropwise at a rate of 5 mL / min. A blue precipitate appeared initially, and the precipitate dissolved as the dropwise addition continued. The dropwise addition was continued until the pH reached 11, and 145 mL of a blue transparent solution was obtained.

[0131] (7) 100 g of the dealuminized Y-type molecular sieve prepared in step (5) was added to the blue transparent solution obtained in step (6), and continuous stirring was performed for 2 h. After filtration, the solid phase was washed with water, and then dried at 115°C for 1.5 h and calcined at 280°C for 2 h, thereby obtaining a modified molecular sieve DZ-13.

[0132] Table 1 shows the composition, unit cell constant, relative crystallinity, framework silica-alumina ratio, structure collapse temperature, specific surface area, and percentage of large secondary pores (pore size of 8 nm to 100 nm) with respect to total secondary pores (2 nm to 100 nm) and total secondary pore volume of DZ-13. After aging of DZ-13 in a bare state at 800°C, 1 atm, 100% water vapor for 17 h, the relative crystallinity of the molecular sieve before and after aging was analyzed by XRD, and the relative crystallinity retention after aging was calculated. The results are shown in Table 2.

[0133] Example 11

[0134] Example 11 illustrates a method for preparing a heavy oil hydrocracking catalyst using the modified Y-type molecular sieve provided in Example 10 as the acidic component of the hydrocracking catalyst and the hydrocracking reaction performance thereof.

[0135] Preparation of the hydrocracking catalyst: 31.5 g of nickel nitrate was dissolved in 300 mL of water, and 60 g of the molecular sieve SZ-10 sample obtained in Example 10 was added to the solution. The solution was heated to 96°C with stirring, and stirring was performed under reflux for 4 h. After filtration, the solid phase was washed twice with deionized water, and then dried at 120°C for 3 h and calcined at 400°C for 2 h. The prepared molecular sieve was tabletted, crushed, sieved, and 40-60 mesh particles were obtained for use.

[0136] Micro-reaction evaluation: n-decane + toluene mixture (weight ratio of 9:1) was used as the reactant. 40-60 mesh catalyst particles 0.5 g were loaded into the reactor, sulfided at 300℃, 4 MPa hydrogen partial pressure, sulfurized oil space velocity 40 h -1 -1, and the hydrogenation activity (toluene conversion rate converted into first-order reaction rate constant) and hydrocracking activity (n-decane conversion rate) of the catalyst were evaluated under the conditions of 360℃, 4 MPa hydrogen partial pressure, and reaction oil space velocity 40 h -1 -1. The results are shown in Table 5.

[0137] The online gas chromatography method was used to analyze the materials after the reaction, and the conditions included: agilent 6850 chromatograph, HP-1 chromatographic column, program temperature measurement, 40℃ for 2 min, 10℃ / min to 160℃, and 2 min. The chromatography-mass spectrometry method was used to qualitatively analyze the cracked hydrocarbons below C10. Toluene (or n-decane) conversion rate = (molar amount of toluene (or n-decane) before reaction - molar amount of toluene (or n-decane) after reaction) / molar amount of toluene (or n-decane) before reaction, and the higher the toluene conversion rate, the better the hydrogenation activity.

[0138] Comparative Example 14

[0139] Comparative Example 14 illustrates the method for preparing a hydrocracking catalyst using the modified Y-type molecular sieve provided in Comparative Example 13 as the acid component of the hydrocracking catalyst and the hydrocracking reaction performance thereof.

[0140] The preparation method of the hydrocracking catalyst and the micro-reaction evaluation method of the hydrocracking reaction performance are the same as those in Example 11, and the results are shown in Table 5.

[0141] Table 1

[0142]

[0143] As can be seen from Table 1, the modified Y-type molecular sieve provided by the present application has a low sodium oxide content, a high silicon-aluminum ratio of the molecular sieve, a low non-framework aluminum content when the silicon-aluminum ratio of the molecular sieve is high, a high percentage of the secondary pore volume of 2.0 nm-100 nm to the total pore volume in the molecular sieve, and a high crystallinity, especially a high crystallinity value when the molecular sieve cell constant is small and the rare earth content is high, a high lattice collapse temperature, and high thermal stability.

[0144] In addition, the method for preparing the modified Y-type molecular sieve provided by the present application can further improve the recovery rate of silicon in the NaY mother liquor to be recovered. The method of the present application can further utilize the residual Si in the NaY mother liquor. As shown in the above Comparative Examples 1-4, the method of the prior art can only achieve a silicon recovery rate of not more than 75%. In contrast, the method according to the present application can achieve a recovery rate of the residual silicon in the NaY mother liquor of 89.2% or more, and even as high as 95.2%. This not only reduces the emission of silicon and relieves the pressure of subsequent processing steps, but also forms the "relay dealumination and silicon supplementation" process described in the present application, and prepares a modified Y-type molecular sieve with higher crystallinity, higher lattice collapse temperature, and higher thermal stability.

[0145] In addition, the method for preparing the modified Y-type molecular sieve provided by the present application can produce a modified Y-type molecular sieve rich in secondary pores. As shown in Table 1, the molecular sieve prepared according to the method of the present application has abundant secondary pores, the pore size of the secondary pores is 2-100 nm, the percentage of the pore volume of the secondary pores to the total pore volume is as high as 44%, and the percentage of the pore volume of the larger secondary pores with a pore size of 8-100 nm to the total pore volume of the secondary pores is 70% or more, which enables the modified Y-type molecular sieve obtained in the present application to have good catalytic performance.

[0146] Table 2

[0147]

[0148] As can be seen from Table 2, the modified Y-type molecular sieve provided by the present application has a relatively high relative crystallinity retention after being aged under harsh conditions of 800℃ for 17 hours in a naked state of the molecular sieve sample, indicating that the modified Y-type molecular sieve provided by the present application has higher hydrothermal stability, which is also derived from the method described in the present application, especially the "relay dealumination and silicon supplementation" process described in the present application.

[0149] A catalyst for heavy oil catalytic cracking was also prepared using the molecular sieve prepared in the present application as an active component, and the catalytic performance was evaluated, as shown in Tables 3-4.

[0150] Table 3 ACE evaluation of raw oil properties

[0151]

[0152] Table 4

[0153]

[0154] As can be seen from Table 4, the catalyst prepared by using the molecular sieve prepared by the present application as the active component has higher conversion rate, higher light oil yield and total liquid yield, and excellent coke selectivity, which is at least partially derived from the excellent thermal stability, abundant secondary pores, and significantly higher framework silica-alumina ratio and relative crystallinity of the modified Y-type molecular sieve obtained by the present application. It can be seen that the modified Y-type molecular sieve provided by the present application has very high hydrothermal stability, significantly lower coke selectivity, significantly higher liquid yield, significantly higher light oil yield, increased gasoline yield, and higher heavy oil conversion activity.

[0155] A catalyst for heavy oil hydrocracking was also prepared by using the molecular sieve prepared by the present application as the active component, and the catalytic performance was evaluated, as shown in Table 5.

[0156] Table 5

[0157] Example No. Molecular sieve No. Toluene conversion / % n-Decane conversion / % Comparative Example 14 DZ-13 19.1 60.7 Example 11 SZ-10 21.1 65.9

[0158] As can be seen from Table 5, the heavy oil hydrocracking catalyst prepared by using the molecular sieve prepared by the present application as the acid component has higher toluene conversion rate and n-decane conversion rate, indicating that the heavy oil hydrocracking catalyst prepared by using the molecular sieve prepared by the present application as the acid component has higher hydrogenation activity (toluene conversion rate) and hydrocracking activity (n-decane conversion rate).

[0159] Unless specifically defined, the terms used in the present application are intended to have the meanings commonly understood by those skilled in the art.

[0160] The embodiments described in the present application are merely for illustrative purposes, and are not intended to limit the protection scope of the present application, and various substitutions, changes and improvements can be made by those skilled in the art without departing from the true spirit and scope of the present application, and thus the present application is not limited to the above-described embodiments, but is defined only by the claims.

Claims

1. A method for preparing a modified Y-type molecular sieve rich in secondary pores, comprising the steps of: (1) contacting a NaY molecular sieve with a NaY mother liquor, adding a dilute aqueous acid solution, and optionally stirring and filtering; (2) contacting the NaY molecular sieve obtained in step (1) with a rare earth salt solution to perform an ion exchange reaction, and optionally filtering and washing to obtain a rare earth element-containing Y-type molecular sieve having a reduced sodium oxide content; (3) subjecting the rare earth element-containing Y-type molecular sieve having a reduced sodium oxide content to a mild hydrothermal ultrastabilization modification treatment, and optionally drying to obtain a Y-type molecular sieve having a reduced unit cell constant; (4) contacting the Y-type molecular sieve having a reduced unit cell constant with a silicon tetrachloride gas to perform a reaction, and optionally washing and filtering to obtain an ultrastabilized modified Y-type molecular sieve; and (5) contacting the gas-phase ultrastabilized modified Y-type molecular sieve obtained in step (4) with an acid solution to perform a channel cleaning modification; wherein in the step (2), the rare earth salt solution is an aqueous solution of a rare earth salt; and the rare earth salt is a rare earth chloride and / or a rare earth nitrate.

2. The method according to claim 1, wherein in the rare earth element-containing Y-type molecular sieve having a reduced sodium oxide content, the rare earth content is 6.5 to 14% by weight as RE2O3, where RE represents a rare earth element; the sodium oxide content is 4 to 8% by weight; and the unit cell constant is 2.465 nm to 2.472 nm.

3. The method according to claim 2, wherein the sodium oxide content is 4.5 to 7.5% by weight.

4. The method according to claim 1, wherein in the step (3), the mild hydrothermal ultrastabilization modification treatment comprises calcining the Y-type molecular sieve at a temperature of 350 to 550°C in an atmosphere containing 40 to 95% by volume of water vapor for 4.5 to 7 hours; and optionally drying.

5. The method according to claim 1, wherein in the step (3), the Y-type molecular sieve having a reduced unit cell constant has a unit cell constant of 2.447 to 2.458 nm, and the Y-type molecular sieve having a reduced unit cell constant has a water content of not more than 1% by weight.

6. The method according to claim 1, wherein in the step (4), the weight ratio of the silicon tetrachloride to the Y-type molecular sieve having a reduced unit cell constant on a dry basis is 0.1 to 0.85: 1, the reaction temperature is 200°C to 600°C, and the reaction time is 10 minutes to 5 hours. wherein in the step (1), the dilute aqueous acid is dilute hydrochloric acid, dilute sulfuric acid or dilute nitric acid, the concentration of the dilute aqueous acid is 0.001 to 0.1 mol / L in terms of the molar concentration of H + in the solution; and wherein in the step (1), the dilute aqueous acid is dilute hydrochloric acid, dilute sulfuric acid or dilute nitric acid, the concentration of the dilute aqueous acid is 0.001 to 0.1 mol / L in terms of the molar concentration of H + in the solution; and 7. The method according to claim 1, wherein in the step (5), the contacting is arranged so that the Y-type molecular sieve is first contacted with a solution of an inorganic acid of medium strength or greater, and then contacted with a solution of an organic acid.

8. The method according to claim 7, wherein the inorganic acid of medium strength or greater is selected from one or more of the following: phosphoric acid, hydrochloric acid, nitric acid, and sulfuric acid.

9. The method according to claim 7, wherein the organic acid is selected from one or more of the following: oxalic acid, malonic acid, succinic acid, methylsuccinic acid, malic acid, tartaric acid, citric acid, and salicylic acid. ​ ​ ​ ​ ​ ​ 10. The method according to claim 7, wherein the contacting is for a period of 60 minutes or more; at a temperature of 80 to 99°C; and the weight ratio of the inorganic acid of medium strength or greater to the molecular sieve is 0.001 to 0.05:1, the weight ratio of the organic acid to the molecular sieve is 0.02 to 0.10:1, and the weight ratio of water to the molecular sieve is 5 to 20:

1.

11. The method according to claim 10, wherein the contacting is for a period of 1 to 4 hours.

12. The method of any one of claims 1-11, wherein, The modified Y-type molecular sieve rich in secondary pores as an active component of a catalytic cracking catalyst, or as an acid component of a hydrocracking catalyst.

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