Modified catalytic cracking catalyst as well as preparation method and application thereof

Abstract

The invention relates to the field of catalytic cracking, in particular to a modified catalytic cracking catalyst and a preparation method and application thereof. The modified catalytic cracking catalyst is of a core-shell structure and comprises an inner core and an outer shell, the inner core contains catalytic cracking catalyst finished product particles and alkaline earth metal elements, and the outer shell contains the alkaline earth metal elements and rare earth metal elements. Compared with other catalysts of the same type, the modified catalytic cracking catalyst has more excellent nickel resistance on the basis of not influencing the catalytic cracking performance, and also has lower dehydrogenation activity.

Description

Technical Field

[0001] The present invention relates to the field of catalytic cracking, and particularly relates to a modified catalytic cracking catalyst, a method for preparing the modified catalytic cracking catalyst, the catalytic cracking catalyst prepared by the method, and the application of the catalytic cracking catalyst in the field of catalytic cracking. Background Art

[0002] In recent years, as world crude oil has been gradually developing towards the direction of heavy and inferior quality, the heavy metals in crude oil, especially the content of metallic nickel, have been gradually increasing, and exist in the forms of porphyrin and non-porphyrin complexes, which cannot be completely removed during the electro-de-salting process. Therefore, heavy metals are continuously alternately circulated during the catalytic cracking reaction and regeneration process, and are continuously deposited on the surface of the catalytic cracking catalyst, causing catalyst poisoning, deteriorating the distribution of catalytic cracking products, and affecting the activity and selectivity of the catalytic cracking catalyst.

[0003] At present, the main way to reduce the poisoning of catalytic cracking catalysts is to use a nickel passivator to form an alloy with the metal, inhibit the deposition of the metal on the surface of the catalytic cracking catalyst, and improve the activity and selectivity of the catalytic cracking catalyst. However, the nickel passivator contains elements such as antimony and bismuth metals, which will be introduced into the catalytic cracking catalyst. According to the "National Hazardous Waste List" in 2021 edition, catalysts containing elements such as antimony and bismuth metals are not environmentally friendly products, and need to be treated as hazardous wastes, with relatively high treatment costs. How to develop an anti-nickel pollution catalytic cracking catalyst with low toxicity and flexible operation has become a technical problem to be solved in the current catalytic cracking field.

[0004] In the prior art, the nickel poisoning mechanism of catalytic cracking catalysts is as follows: the nickel-containing metal complexes in crude oil decompose at high temperatures, and the generated nickel after decomposition will be deposited on the surface of the catalytic cracking catalyst. Among them, part of the nickel is dispersed on the silicon-rich matrix (such as high-silicon or dealuminated zeolite), and during the catalytic cracking reaction process, it is highly dispersed in the matrix in the form of relatively stable nickel aluminate or nickel silicoaluminate, and is only reduced to nickel at a higher temperature; another part of the nickel is attached to the surface of the catalytic cracking catalyst in the form of nickel oxide nanoparticles, and during the catalytic cracking reaction process, it is reduced to metallic nickel, which is relatively easy to aggregate, and the toxicity is smaller than when it is evenly dispersed.

[0005] The toxicity of nickel is manifested as a strong catalytic dehydrogenation effect, which seriously affects the selectivity of the catalytic cracking catalyst, deteriorates the distribution of catalytic cracking products, increases the yields of hydrogen and carbon, and is not conducive to increasing the economic benefits of refineries. Based on the above nickel poisoning mechanism of catalytic cracking catalysts, it is necessary to specifically propose methods to improve the anti-nickel pollution performance.

[0006] CN102513163A discloses a water-soluble catalytic cracking metal passivator and its preparation method. The invention relates to a catalytic cracking metal passivator and its preparation method, especially a water-soluble catalytic cracking metal passivator and its preparation method. The metal passivator includes a nickel passivator and a vanadium passivator. The nickel passivator is antimony pentoxide sol, and the vanadium passivator is an aqueous solution of an organic acid salt of lanthanum or cerium. The content of antimony in the passivator is 8%-30%, and the content of lanthanum or cerium is 0%-7%. The invention adopts the preparation process of hydrogen peroxide, with a short reaction time, no external heating required, energy saving and consumption reduction. The prepared passivator is convenient to use and has stable properties, and can be infinitely miscible with water. However, the design of this scheme involves antimony metal, which is not conducive to the subsequent post-treatment of the catalytic cracking equilibrium catalyst.

[0007] CN105828932A discloses an FCC catalyst composition containing boron oxide and phosphorus for resisting catalytic cracking metal poisoning. The boron-based anti-metal catalytic cracking catalyst of this company conducts nickel passivation treatment by utilizing the migration of boron, and synthesizes a first particle type containing one or more boron oxide components and a second particle type containing a phosphorus component and 20%-95% zeolite. For the catalytic cracking of residue oil containing vanadium and nickel, it has a lower hydrogen and coke yield. However, this patent does not explain how to avoid damaging the molecular sieve during the preparation process. In addition, the metal pollution level corresponding to this method is relatively low, and no relevant implementation for resisting high metal pollution is carried out.

[0008] CN112108171A discloses a preparation method of an anti-heavy metal catalytic cracking catalyst. This method prepares a precursor of the catalytic cracking catalyst through an in-situ crystallization reaction, and prepares an anti-heavy metal catalytic cracking catalyst by subjecting the in-situ crystallization microspheres to aluminum salt, acid exchange and rare earth impregnation. By using aluminum salt, acid and rare earth modification and exchange to adjust the pore structure, the metal resistance of the catalyst is improved. However, the preparation process of this method is relatively long and complex, which is not conducive to industrial promotion and application. It will also affect the activity of the main agent and the product distribution, resulting in a reduction in the yield of high-value products such as gasoline and liquefied gas.

[0009] CN115957799A discloses a complex and its application in the preparation of a heavy catalytic cracking catalyst resistant to metal pollution. The invention introduces a modified metal element resistant to pollution metal into the catalytic cracking catalyst by mixing a complexing agent and a modified metal ion in a molar ratio of 0.5:1 to 10:1, and can have a good anti-metal pollution effect under the condition of a relatively low content of the modified metal. The invention needs to apply the catalyst precursor microspheres, and carry out exchange treatment modification through the interactive contact of the complex solution and the aluminum compound dispersion liquid. This product has a lower hydrogen and coke yield, and can significantly reduce the hydrogen-methane ratio. Compared with the catalysts prepared by other methods, the catalytic cracking catalyst provided by the invention has a lower dry gas and hydrogen-methane ratio and a lower hydrogen yield in the presence of polluting metals. Summary of the Invention

[0010] The object of the present invention is to overcome the problem of serious metal pollution, especially nickel pollution, existing in the existing catalytic cracking reaction, and to provide a modified catalytic cracking catalyst, a method for preparing the modified catalytic cracking catalyst, the catalytic cracking catalyst prepared by the method, and the application of the catalytic cracking catalyst in the field of catalytic cracking. Among them, compared with other catalysts of the same type, the catalyst of the present invention has more excellent nickel resistance on the basis of not affecting the catalytic cracking performance, and at the same time has lower dehydrogenation activity.

[0011] To achieve the above object, the present invention provides a modified catalytic cracking catalyst in the first aspect. Among them, the modified catalytic cracking catalyst has a core-shell structure, including a core and a shell;

[0012] Among them, the core contains finished product particles of the catalytic cracking catalyst and alkaline earth metal elements, and the shell contains alkaline earth metal elements and rare earth metal elements;

[0013] The mass of the alkaline earth metal element in terms of oxide accounts for 0.01-0.9% of the total mass of the modified catalytic cracking catalyst.

[0014] The present invention provides a method for preparing a modified catalytic cracking catalyst in the second aspect. The method includes the following steps:

[0015] (1) In the presence of a solvent, contact the finished product particles of the catalytic cracking catalyst with an alkaline earth metal compound to obtain a first material;

[0016] (2) Contact the solution containing alkaline earth metal elements and the solution containing modified elements with the first material respectively, and after drying, obtain the modified catalytic cracking catalyst.

[0017] The present invention provides a modified catalytic cracking catalyst prepared by the method described in the second aspect in the third aspect.

[0018] The present invention provides an application of the modified catalytic cracking catalyst described in the first aspect or the third aspect in the field of catalytic cracking, preferably the application of resisting Ni and V in the field of catalytic cracking.

[0019] Without changing the internal structure and catalytic cracking activity of the catalytic cracking catalyst, the present invention introduces alkaline earth metal elements into the core and shell of the catalyst, and introduces alkaline earth metal elements and rare earth metal elements into the shell of the catalyst. Among them, the rare earth metal elements in the shell can effectively interact with vanadium, improving the performance of the catalytic cracking catalyst against vanadium poisoning. The alkaline earth metal elements in the shell can effectively combine with the nickel element, a pollution source in the catalyst, to form a eutectic, increasing the reduction temperature of the nickel element, thereby enhancing the nickel resistance of the catalytic cracking catalyst, reducing the poisoning of the catalyst, and improving the dehydrogenation activity of the catalytic cracking catalyst of the catalyst; the presence of the alkaline earth metal elements in the core can cause the nickel elements remaining dispersed in the high-silica matrix to combine with the alkaline earth metal elements, further improving the performance of the catalytic cracking catalyst.

[0020] Compared with the existing catalytic cracking catalysts, the catalyst of the present invention has the characteristics of environmental friendliness and economy; at the same time, the preparation process of the catalyst of the present invention is simple, which is conducive to large-scale industrial production and application. Detailed implementation manners

[0021] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0022] To achieve the above object, the first aspect of the present invention provides a modified catalytic cracking catalyst, wherein the modified catalytic cracking catalyst has a core-shell structure, including a core and a shell;

[0023] Among them, the core contains finished catalytic cracking catalyst particles and alkaline earth metal elements, and the shell contains alkaline earth metal elements and rare earth metal elements;

[0024] The mass of the alkaline earth metal element calculated as the oxide accounts for 0.01-0.9% of the total mass of the modified catalytic cracking catalyst.

[0025] In the present invention, the shell refers to the thickness of the modified elements coated on the outer layer of the finished catalyst particles.

[0026] According to a preferred embodiment of the present invention, the mass of the alkaline earth metal element calculated as the oxide accounts for 0.3-0.7% of the total mass of the modified catalytic cracking catalyst. The alkaline earth metal elements within the above range can effectively combine with the equivalent reduced-state nickel elements in the catalyst to form a solid solution with a certain chemical combination ratio (for example, nickel combines with the alkaline earth metal magnesium to form a nickel-magnesium solid solution), increasing the reduction temperature of the nickel element.

[0027] According to a preferred embodiment of the present invention, the alkaline earth metal element is selected from one or more of magnesium element, calcium element and barium element, and more preferably magnesium element. Selecting the alkaline earth metal element within a more preferred range can better combine with nickel element without changing the product distribution of the fluid catalytic cracking catalyst, and form a more stable eutectic.

[0028] According to a preferred embodiment of the present invention, the alkaline earth metal element in the inner core accounts for 20wt%-40wt% of the total amount of all alkaline earth metal elements in the catalyst. For example, it can be specific percentage contents such as 20wt%, 22wt%, 24wt%, 26wt%, 28wt%, 30wt%, 32wt%, 34wt%, 36wt%, 38wt%, 40wt% or the range between the two. Preferably, the alkaline earth metal element in the inner core accounts for 25wt%-35wt% of the total amount of all alkaline earth metal elements in the catalyst. When the alkaline earth metal element in the inner core accounts for 25wt%-35wt% of the total amount of all alkaline earth metal elements in the catalyst, the synergistic effect between the alkaline earth metal element in the inner core and the alkaline earth metal element in the outer shell can be further improved, so that nickel deposited on the surface of the fluid catalytic cracking catalyst and partially dispersed on the silica-rich matrix combines with the modified alkaline earth metal element and forms a solid solution (for example, nickel combines with alkaline earth metal magnesium to form a nickel-magnesium solid solution), the reduction temperature of nickel is increased, the strong catalytic dehydrogenation effect after catalyst nickel poisoning is reduced, and further the influence on the fluid catalytic cracking selectivity after catalyst nickel poisoning is reduced.

[0029] According to a preferred embodiment of the present invention, the mass of the rare earth metal element in the form of oxide in the outer shell accounts for 0.5-2% of the total mass of the modified fluid catalytic cracking catalyst, and preferably 0.5-1.5%.

[0030] According to a preferred embodiment of the present invention, the rare earth metal element is selected from cerium element and / or lanthanum element, and preferably cerium element. Using the rare earth metal element within a preferred range can better promote the combination of the alkaline earth metal element and the contaminant metal, and improve the metal resistance performance of the fluid catalytic cracking catalyst.

[0031] According to a preferred embodiment of the present invention, the molar ratio of the alkaline earth metal element to the rare earth metal element in the outer shell is 1-3, and preferably 1.5-2. By using the above preferred range of molar ratio, the anti-nickel and anti-vanadium effects of the alkaline earth metal element and the rare earth metal element can be further improved, and the metal resistance performance of the fluid catalytic cracking catalyst can be improved.

[0032] According to a preferred embodiment of the present invention, the average particle size of the modified fluid catalytic cracking catalyst is 72 - 80 μm, preferably 74 - 78 μm. By using the average particle size within the preferred range, the uniformity of the distribution of the modifying elements in the pore channels and on the surface of the catalyst particles can be further improved, thereby better promoting the combination of the alkaline earth metal element and the nickel element.

[0033] According to a preferred embodiment of the present invention, the shell thickness is 0.2 - 3.5 μm, preferably 1 - 3 μm. The shell thickness within the above preferred range can further enhance the synergistic effect between the alkaline earth metal element in the core and the alkaline earth metal element in the shell, enabling the nickel deposited on the surface of the fluid catalytic cracking catalyst and partially dispersed on the silica-rich matrix to combine with the alkaline earth metal element and form a solid solution (for example, nickel combines with the alkaline earth metal magnesium to form a nickel-magnesium solid solution), increasing the reduction temperature of nickel, reducing the strong catalytic dehydrogenation effect after the catalyst is poisoned by nickel, and further reducing the impact on the fluid catalytic cracking selectivity after the catalyst is poisoned by nickel.

[0034] In the present invention, the shell thickness is half of the difference between the particle size of the modified fluid catalytic cracking catalyst and the particle size of the finished catalyst particles.

[0035] According to a preferred embodiment of the present invention, the specific surface area of the modified fluid catalytic cracking catalyst is 250 - 290 m 2 / g.

[0036] According to a preferred embodiment of the present invention, the pore volume of the modified fluid catalytic cracking catalyst is 0.35 - 0.45 mL / g.

[0037] The second aspect of the present invention provides a method for preparing a modified fluid catalytic cracking catalyst, which includes the following steps:

[0038] (1) In the presence of a solvent, contacting the finished catalyst particles of fluid catalytic cracking with an alkaline earth metal compound to obtain a first material;

[0039] (2) Separately contacting the solution containing the alkaline earth metal element and the solution containing the modifying element with the first material, and after drying, obtaining the modified fluid catalytic cracking catalyst.

[0040] In the present invention, for the selection of the contact temperature and contact time in step (1), the range is relatively wide, as long as sufficient contact can be achieved, and those skilled in the art can select according to actual needs. Preferably, the contact temperature is 10 - 60 °C and the contact time is 30 - 80 min.

[0041] In the present invention, the selection range of the contact method in step (1) is relatively wide, as long as sufficient contact can be achieved, and those skilled in the art can make a selection according to actual needs. For example, sufficient contact between the finished particles of the fluid catalytic cracking catalyst and the alkaline earth metal compound enables the introduction of alkaline earth metal elements into the pores of the finished catalyst particles by an exchange method.

[0042] According to a preferred embodiment of the present invention, in step (1), the solvent is water or acidic water, preferably acidic water.

[0043] According to a preferred embodiment of the present invention, in step (1), the pH value of the first material is less than 7.5. For example, the pH value of the first material is specific values such as 3, 3.5, 4, 4.5, 5, 5.5, 6, 6.5, 7, 7.5 or a range between any values; more preferably, the first material is acidic; further preferably, the pH value of the first material is 4 - 6.5. By using the pH within the above further preferred range, the exchange degree between the modified Mg element and Na in the finished catalyst particles can be more effectively improved.

[0044] In the present invention, the selection range of the amount of the solvent in step (1) is relatively wide, as long as sufficient contact between the finished particles of the fluid catalytic cracking catalyst and the alkaline earth metal compound can be achieved, and those skilled in the art can make a selection according to actual needs. Preferably, the mass amount of the solvent is 2 - 6 times the mass amount of the finished catalyst particles.

[0045] According to a preferred embodiment of the present invention, the alkaline earth metal element in the alkaline earth metal compound is selected from one or more of magnesium element, calcium element, and barium element, preferably magnesium element. Using the alkaline earth metal element within a more preferred range can better promote the combination of the alkaline earth metal element and the nickel element to form a more stable eutectic.

[0046] According to a preferred embodiment of the present invention, the alkaline earth metal compound is an alkaline earth metal salt and its oxide, more preferably one or more of magnesium chloride, magnesium sulfate, magnesium oxide, calcium chloride, calcium oxide, barium chloride, and barium oxide, and further preferably magnesium chloride and / or magnesium sulfate.

[0047] In the present invention, the selection range of the solvent in step (1) is relatively wide, as long as sufficient contact can be achieved, and those skilled in the art can make a selection according to actual needs. Preferably, the solvent is water or acidic water.

[0048] According to a preferred embodiment of the present invention, in step (1), the method includes: filtering the obtained first material. In the present invention, there is no particular limitation on the filtering method, as long as solid-liquid separation can be achieved, and those skilled in the art can select according to actual needs. Preferably, the filtering method is filtering in a suction flask.

[0049] In the present invention, the selection ranges of the drying temperature and drying time in step (2) are relatively wide, as long as drying can be achieved, and those skilled in the art can select according to actual needs. Preferably, the drying temperature is 140 - 210 °C.

[0050] In the present invention, the selection ranges of the contact methods in step (2) are relatively wide, as long as sufficient contact can be achieved, and those skilled in the art can select according to actual needs. Preferably, the contact method is rinsing.

[0051] According to a preferred embodiment of the present invention, in step (2), the contact sequence is to first contact the first material with a solution containing an alkaline earth metal element (preferably rinsing), and then contact the first material with a solution containing a rare earth metal element (preferably rinsing). Contacting the first material in the above sequence can enable the alkaline earth metal elements to be uniformly dispersed inside the pores of the catalyst and deposited on the catalytic surface in the form of exchange. For example, the alkaline earth metal compound exchanges the alkaline earth metal elements into the pores of the finished catalytic cracking catalyst particles through sufficient contact with the finished catalytic cracking catalyst particles, and the solution containing the alkaline earth metal elements introduces the alkaline earth metal elements to the surface of the first material by rinsing, ultimately obtaining a modified catalytic cracking catalyst.

[0052] According to a preferred embodiment of the present invention, in step (2), before contacting the first material with the solution containing an alkaline earth metal element and the solution containing a modifying element respectively, the method further includes: contacting the first material with an alkaline solution. Contacting the first material with the alkaline solution can increase the number of Brønsted acid sites of the catalytic cracking catalyst and improve the activity of the catalytic cracking catalyst. Preferably, the contact method between the alkaline solution and the first material is rinsing.

[0053] According to a preferred embodiment of the present invention, the alkaline solution is ammonia water, more preferably ammonia water with a concentration of 3 - 10 wt%. Using ammonia water within the more preferred range can better contact the catalyst uniformly and improve the distribution state of the acid sites of the catalytic cracking catalyst.

[0054] According to a preferred embodiment of the present invention, relative to 100 parts by weight of the finished catalytic cracking catalyst particles, the dosage of ammonia water calculated as NH4 + is 1 - 5 parts by weight. Using ammonia water within the above range can better contact the catalyst uniformly and improve the distribution state of the acid sites of the catalytic cracking catalyst.

[0055] In the present invention, unless otherwise specified, the weight of the finished catalytic cracking catalyst particles is measured on a dry basis.

[0056] According to a preferred embodiment of the present invention, the rare earth metal element is cerium element and / or lanthanum element, and more preferably cerium element. Using rare earth metal elements within the preferred range can better endow the catalytic cracking catalyst with the performance of resisting vanadium poisoning and improve the anti-metal performance of the catalytic cracking catalyst.

[0057] According to a preferred embodiment of the present invention, relative to 100 parts by weight of the finished catalytic cracking catalyst particles, the amount of the alkaline earth metal compound in terms of alkaline earth metal oxide is 0.05 - 1 part by weight, preferably 0.1 - 0.5 part by weight. The alkaline earth metal elements in the above preferred dosage range can effectively perform ion exchange with the finished catalyst particles and better introduce the alkaline earth metal elements into the internal pores of the catalyst.

[0058] According to a preferred embodiment of the present invention, relative to 100 parts by weight of the finished catalytic cracking catalyst particles, the amount of the solution containing alkaline earth metal elements in terms of alkaline earth metal element oxide is 0.05 - 1 part by weight, preferably 0.1 - 0.5 part by weight. The alkaline earth metal elements in the above preferred dosage range can effectively coat the surface of the finished catalyst particles and better form a catalyst shell containing alkaline earth metal elements.

[0059] According to a preferred embodiment of the present invention, the amount of the alkaline earth metal compound in step (1) and the amount of the solution containing alkaline earth metal elements in step (2) are such that in the prepared catalyst, the alkaline earth metal elements in the core account for 20% - 40% of the total mass of all alkaline earth metal elements in the catalyst. Using the alkaline earth metal compound in the above dosage range, the prepared modified catalytic cracking catalyst has a more excellent cooperation effect, can effectively improve the combination of alkaline earth metal elements and nickel from both the surface and internal pores of the catalyst, and form a solid solution (for example, nickel combines with alkaline earth metal magnesium to form a nickel-magnesium solid solution) during the catalytic cracking reaction regeneration process, thereby improving the anti-nickel poisoning ability of the catalyst.

[0060] In the present invention, the selection range of the type of the solution containing alkaline earth metal elements is relatively wide, as long as it contains alkaline earth metal elements, and those skilled in the art can select according to actual needs.

[0061] According to a preferred embodiment of the present invention, relative to 100 parts by weight of the finished catalytic cracking catalyst particles, the amount of the solution containing rare earth metal elements in terms of rare earth metal element oxide is 0.5 - 5 parts by weight, preferably 1 - 2 parts by weight.

[0062] In the present invention, the types of solutions containing the modifying element have a relatively wide selection range, as long as they contain the modifying element, and those skilled in the art can select according to actual needs.

[0063] According to a preferred embodiment of the present invention, the molar ratio of the alkaline earth metal element to the rare earth metal element in the outer shell is 1 - 3, preferably 1.5 - 2. By adopting the molar ratio of the alkaline earth metal element to the rare earth metal element within the preferred range, it is possible to better promote the modified fluid catalytic cracking catalyst to have both vanadium poisoning resistance performance and improve the metal resistance performance of the fluid catalytic cracking catalyst.

[0064] According to a preferred embodiment of the present invention, the preparation method of the modified fluid catalytic cracking catalyst is also applicable to the production of modified fluid catalytic cracking catalysts on an industrial scale.

[0065] In the present invention, the types of finished particles of the fluid catalytic cracking catalyst have a relatively wide selection range, as long as they have a catalytic effect in the fluid catalytic cracking reaction, and those skilled in the art can select according to actual needs. Preferably, the finished particles of the fluid catalytic cracking catalyst are prepared by mixing molecular sieve, pseudo - boehmite (calculated as alumina), aluminum sol (calculated as solute), kaolin, and hydrochloric acid in a mass ratio of 30 - 40:15 - 25:5 - 10:30 - 45; more preferably, the solid content of the finished particles of the fluid catalytic cracking catalyst is 85 - 90 wt%, wherein the solids in the finished particles of the fluid catalytic cracking catalyst include 40 - 50 wt% of Al2O3, 41 - 57 wt% of SiO2, 1 - 4 wt% of Re2O3, 0.1 - 0.3 wt% of Na2O, 0.5 - 1.5 wt% of Cl element, 0.5 - 1.5 wt% of SO3, 0.2 - 0.8 wt% of Fe2O3, and 0.2 - 1 wt% of P2O5.

[0066] The third aspect of the present invention provides a modified fluid catalytic cracking catalyst prepared by the method described in the second aspect.

[0067] The fourth aspect of the present invention provides an application of the modified fluid catalytic cracking catalyst described in the first aspect or the third aspect in the field of fluid catalytic cracking, preferably for the application of resisting Ni and V in the field of fluid catalytic cracking.

[0068] In the present invention, the analysis of the composition of each material is carried out by the XRF fluorescence analysis method (RIPP 117 - 90 standard method), as described in "Petrochemical Analysis Methods" (RIPP Test Methods), edited by Yang Cuideng et al., published by Science Press in 1990.

[0069] In the present invention, the specific surface area is measured by the GB5816 standard method.

[0070] In the present invention, the pore volume is measured by the GB5816 standard method.

[0071] In the present invention, the method for measuring the average particle size is to analyze and measure using a laser particle size analyzer according to the ASTM D4464-15 standard.

[0072] The present invention will be described in detail below through examples. In the following preparation examples, the SOY-12 molecular sieve is produced by Qilu Branch of the catalyst; the pseudo-boehmite is produced by Shandong Aluminum Co., Ltd.; the aluminum sol is produced by Qilu Branch of the catalyst, and its aluminum content is 12% by weight; the kaolin is produced by Suzhou Kaolin Co., Ltd.

[0073] Preparation Example

[0074] (1) Mix 35 parts by weight of SOY-12 molecular sieve, 20 parts by weight of pseudo-boehmite calculated as alumina, 8 parts by weight of aluminum sol calculated as solute, 37 parts by weight of kaolin, and 4 parts by weight of 31 wt% hydrochloric acid calculated as HCl to obtain a slurry.

[0075] (2) Spray-dry and form the slurry obtained in step (1), and calcine it at 500 °C for 2 h to obtain a first solid.

[0076] (3) Wash the first solid obtained in step (2) with a large amount of 0.5 wt% ammonium sulfate solution, wash it twice in total. After washing, dry it at 150 °C for 5 h to obtain the finished product particles of the fluid catalytic cracking catalyst.

[0077] The solid content of the finished product particles of the fluid catalytic cracking catalyst is 88% by weight. The solids in the finished product particles of the fluid catalytic cracking catalyst include 50.0 parts by weight of Al2O3, 40.5 parts by weight of SiO2, 4.5 parts by weight of Re2O3, 0.08 parts by weight of Na2O, 0.55 parts by weight of Cl element, 0.45 parts by weight of SO3, 0.55 parts by weight of Fe2O3, and 0.45 parts by weight of P2O5.

[0078] The following is the preparation method of the modified fluid catalytic cracking catalyst.

[0079] Example 1

[0080] (1) At 25 °C, mix 100 g of the finished product particles of the fluid catalytic cracking catalyst (with an average particle size of 72 μm based on dry basis), 0.1 g of light magnesium oxide, and 400 g of distilled water for 60 min to obtain a first material;

[0081] (2) Filter the first material obtained in step (1) in a suction flask to obtain a filter cake; then wash the filter cake with 2 g of 6 wt% ammonia water calculated as NH4 + to obtain a second material;

[0082] (3) The second material was successively leached with 0.5 g of 6 wt% magnesium sulfate solution (calculated as magnesium oxide) and 1 g of 5.8 wt% cerium chloride solution (calculated as cerium oxide) to obtain the third material, which was dried at 120 °C for 2 h to obtain the modified fluid catalytic cracking catalyst CAT-1.

[0083] Example 2

[0084] The preparation steps were the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used was 0.5 g; in step (3), the amount of magnesium sulfate solution added was 0.1 g (calculated as magnesium oxide), to obtain the modified fluid catalytic cracking catalyst CAT-2.

[0085] Example 3

[0086] The preparation steps were the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used was 0.3 g; in step (3), the amount of magnesium sulfate solution added was 0.3 g (calculated as magnesium oxide), to obtain the modified fluid catalytic cracking catalyst CAT-3.

[0087] Example 4

[0088] The preparation steps were the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used was 0.05 g; in step (3), the amount of magnesium sulfate solution added was 0.8 g (calculated as magnesium oxide), to obtain the modified fluid catalytic cracking catalyst CAT-4.

[0089] Example 5

[0090] The preparation steps were the same as those in Example 2, except that in step (1), the amount of light magnesium oxide used was 0.8 g; in step (3), the amount of magnesium sulfate solution added was 0.05 g (calculated as magnesium oxide), to obtain the modified fluid catalytic cracking catalyst CAT-5.

[0091] Example 6

[0092] The preparation steps were the same as those in Example 3, except that in step (2), the concentration of ammonia water (calculated as NH4 + was 10 wt%; in step (3), the amount of cerium chloride solution added was 2 g (calculated as cerium oxide).

[0093] Comparative Example 1

[0094] The preparation steps were the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used was 0; in step (2), the amount of ammonia water added was 0; in step (3), the amount of magnesium sulfate solution added was 0, and finally the modified fluid catalytic cracking catalyst CAT-DB1 was obtained.

[0095] Comparative Example 2

[0096] The preparation steps are the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used is 0; in step (3), the amount of magnesium sulfate solution added is 1 g (calculated as magnesium oxide), and finally the modified fluid catalytic cracking catalyst CAT-DB2 is obtained.

[0097] Comparative Example 3

[0098] The preparation steps are the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used is 1.5 g; in step (3), the amount of magnesium sulfate solution added is 0, and finally the modified fluid catalytic cracking catalyst CAT-DB3 is obtained.

[0099] Comparative Example 4

[0100] The preparation steps are the same as those in Example 1, except that in step (1), the amount of light magnesium oxide used is 1 g; in step (3), the amount of magnesium sulfate solution added is 1 g (calculated as magnesium oxide), and finally the modified fluid catalytic cracking catalyst CAT-DB4 is obtained.

[0101] The physical and chemical properties of the catalysts prepared in Examples 1-6 and Comparative Examples 1-4 are shown in Table 1, where RE2O3 is a rare earth metal oxide.

[0102] Table 1

[0103]

[0104]

[0105] Note: The mass ratio of MgO in the core refers to the proportion of alkaline earth metal elements in the core to the total mass of all alkaline earth metal elements in the catalyst.

[0106] The following is the evaluation method for the modified fluid catalytic cracking catalyst.

[0107] Test Example 1

[0108] The equilibrium catalyst or the fresh catalyst and additives after steam aging treatment are loaded into a fixed-bed reactor. Using STDF-1 standard oil as the feedstock, after it is fully vaporized in the preheating section of the reactor, it enters the catalyst and additive bed layer, and cracking or pyrolysis reactions are carried out under specified conditions. The liquid products obtained are analyzed by chromatography and the microactivity index of the catalyst and additives is calculated through a formula.

[0109] Test Example 2

[0110] The characterization method of the catalyst core-shell structure is based on the analysis method of scanning electron microscopy combined with X-ray energy spectrometer, which is simply called SEM-EDS analysis technology. The scanning electron microscope used is the QUANTA 200F+EDAX produced by FEI Company in the Netherlands. The conditions for measuring the fluid catalytic cracking catalyst by scanning electron microscope can include: the acceleration voltage is 20KV, the resolution is 3.5nm, and the magnification is 1000. The fixed dissolution and drying method is used to slice and prepare the samples of the fluid catalytic cracking catalyst, and the content of metal elements is read according to the peak intensity data measured by SEM-EDS.

[0111] Test Example 3

[0112] (1) The modified fluid catalytic cracking catalysts prepared in the examples and comparative examples were subjected to cyclic contamination (to deposit Ni and V) experiments on a cyclic aging device. The specific steps are as follows:

[0113] Heavy metals (Ni and V) were introduced into the catalyst mixture by the Michel impregnation method, and then the catalyst mixture after introducing heavy metals was loaded into a small fixed fluidized bed and processed on the small fixed fluidized bed device according to the following steps:

[0114] (a) Under a nitrogen atmosphere, it was heated to 600°C at a heating rate of 20°C / min.

[0115] (b) At a heating rate of 1.5°C / min, after heating to 780°C, it was kept at a constant temperature of 780°C. During the constant temperature process, the treatment atmosphere was changed according to the following steps:

[0116] (i) It was treated with an atmosphere containing 40% by volume of nitrogen (wherein the nitrogen contains 5% by volume of propylene) and 60% by volume of water vapor for 10 minutes;

[0117] (ii) It was treated with an atmosphere containing 40% by volume of nitrogen (pure nitrogen, without propylene) and 60% by volume of water vapor for 10 minutes;

[0118] (iii) It was treated with an atmosphere containing 40% by volume of air (containing 4000 ppm SO2) and 60% by volume of water vapor for 10 minutes;

[0119] (iv) It was treated with an atmosphere containing 40% by volume of nitrogen and 60% by volume of water vapor for 10 minutes; then the cyclic steps (i)-(iv) were repeated in the foregoing order once again, and then step (i) was repeated to end the cyclic contamination step;

[0120] (2) Steps for aging: The catalyst mixture after cyclic contamination was aged at 800°C in an atmosphere containing 100% by volume of water vapor for 4 hours;

[0121] (3) Investigate the catalytic performance of the catalyst mixture after cyclic contamination-aging on the ACE device; the specific evaluation conditions and results are shown in Table 3. Among them: the composition of the reaction feedstock oil is shown in Table 2.

[0122] Table 2

[0123]

[0124] Catalyst-oil ratio = mass of catalytic cracking catalyst / mass of reaction feedstock oil Conversion rate = gasoline yield + liquefied gas yield + dry gas yield + coke yield, Light oil yield = gasoline yield + diesel yield,

[0125] Coke selectivity = coke yield / conversion rate,

[0126] Dry gas selectivity = dry gas yield / conversion rate.

[0127] Table 3

[0128]

[0129]

[0130] The data in Table 3 show that the catalytic cracking catalyst prepared by the method of the embodiment of the present invention has good resistance to heavy metal (Ni 3000 μg / g, V 1000 μg / g) contamination, and has better catalytic cracking activity compared with the catalyst of the comparative example and the catalytic cracking catalyst. The hydrogen-methane ratio of the catalytic cracking reaction is significantly reduced. The catalyst of the present invention has a high conversion rate when applied to the catalytic cracking reaction of the feedstock oil, low selectivity of coke and dry gas, low hydrogen-methane ratio, low catalytic dehydrogenation selectivity, and strong nickel poisoning resistance of the catalyst.

[0131] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the technical concept scope of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A modified fluid catalytic cracking catalyst, characterized in that, The modified fluid catalytic cracking catalyst has a core-shell structure, including a core and a shell; Wherein, the core contains finished fluid catalytic cracking catalyst particles and alkaline earth metal elements, and the shell contains alkaline earth metal elements and rare earth metal elements; The mass of the alkaline earth metal elements calculated as oxides accounts for 0.01-0.9% of the total mass of the modified fluid catalytic cracking catalyst.

2. The modified fluid catalytic cracking catalyst according to claim 1, wherein, The mass of the alkaline earth metal elements calculated as oxides accounts for 0.3-0.7% of the total mass of the modified fluid catalytic cracking catalyst; Preferably, the alkaline earth metal elements are selected from one or more of magnesium element, calcium element and barium element, and more preferably magnesium element; Preferably, the alkaline earth metal elements in the core account for 20%-40% of the total mass of all alkaline earth metal elements in the catalyst, preferably 25%-35%.

3. The modified fluid catalytic cracking catalyst according to claim 1 or 2, wherein, The mass of the rare earth metal elements calculated as oxides in the shell accounts for 0.5-2% of the total mass of the modified fluid catalytic cracking catalyst, preferably 0.5-1.5%; Preferably, the rare earth metal elements are selected from cerium element and / or lanthanum element, and preferably cerium element; Preferably, the molar ratio of the alkaline earth metal elements to the rare earth metal elements in the shell is 1-3, preferably 1.5-2.

4. The modified fluid catalytic cracking catalyst according to any one of claims 1-3, wherein, The thickness of the shell is 0.2-3.5μm, preferably 1-3μm; Preferably, the average particle size of the modified fluid catalytic cracking catalyst is 72-80μm, preferably 74-78μm; Preferably, the specific surface area of the modified fluid catalytic cracking catalyst is 250-290 m 2 / g.

5. A preparation method of a modified fluid catalytic cracking catalyst, the method comprising the following steps: (1) In the presence of a solvent, contacting the finished fluid catalytic cracking catalyst particles with an alkaline earth metal compound to obtain a first material; (2) Separately contacting a solution containing alkaline earth metal elements and a solution containing rare earth metal elements with the first material, and after drying, obtaining the modified fluid catalytic cracking catalyst.

6. The method according to claim 5, wherein In step (1), the contact temperature is 10-60°C and the contact time is 30-80 min; Preferably, in step (2), the drying temperature is 140-210°C; Preferably, in step (2), the contact method is leaching; Preferably, before separately contacting the solution containing alkaline earth metal elements and the solution containing rare earth metal elements with the first material in step (2), the method further comprises: contacting an alkaline solution with the first material; Preferably, the alkaline solution is ammonia water, more preferably 3-10 wt% ammonia water; Preferably, relative to 100 parts by weight of the finished catalytic cracking catalyst particles, the amount of ammonia water in terms of NH4 + is 1 to 5 parts by weight.

7. The method according to claim 5 or 6, wherein The alkaline earth metal elements in the alkaline earth metal compound are selected from one or more of magnesium element, calcium element and barium element, and preferably magnesium element; Preferably, the alkaline earth metal compound is an alkaline earth metal salt and its oxide, more preferably one or more of magnesium chloride, magnesium sulfate, magnesium oxide, calcium chloride, calcium oxide, barium chloride and barium oxide, and further preferably magnesium chloride and / or magnesium sulfate; Preferably, the solvent in step (1) is water or acidic water; Preferably, in step (1), the pH value of the first material is less than 7.5, and more preferably, the first material is acidic; Preferably, the rare earth metal elements are cerium element and / or lanthanum element, and more preferably cerium element.

8. The method according to any one of claims 5-7, wherein, In step (1), the dosage of the alkaline earth metal compound in terms of alkaline earth metal oxide is 0.05 - 1 part by weight, preferably 0.1 - 0.5 part by weight, based on 100 parts by weight of the finished fluid catalytic cracking catalyst particles; Preferably, in step (2), the dosage of the solution containing an alkaline earth metal element in terms of alkaline earth metal element oxide is 0.05 - 1 part by weight, preferably 0.1 - 0.5 part by weight, based on 100 parts by weight of the finished fluid catalytic cracking catalyst particles; Preferably, the dosage of the alkaline earth metal compound in step (1) and the dosage of the solution containing an alkaline earth metal element in step (2) are such that in the prepared catalyst, the alkaline earth metal element in the core accounts for 20% - 40% of the total mass of all alkaline earth metal elements in the catalyst; Preferably, the dosage of the solution containing a rare earth metal element in terms of rare earth metal element oxide is 0.5 - 5 parts by weight, preferably 1 - 2 parts by weight, based on 100 parts by weight of the finished fluid catalytic cracking catalyst particles; Preferably, the dosages of the solution containing an alkaline earth metal element and the solution containing a rare earth metal element are such that the molar ratio of the alkaline earth metal element to the rare earth metal element in the shell is 0.5 - 3, preferably 1.0 - 2.

5.

9. A modified fluid catalytic cracking catalyst prepared by the method according to any one of claims 5 - 8.

10. Use of the modified fluid catalytic cracking catalyst according to any one of claims 1 - 4 and 9 in the field of fluid catalytic cracking, preferably for resistance to Ni and V in the field of fluid catalytic cracking.

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