A process for the preparation of a catalytic cracking aid

Abstract

The application discloses a preparation method of a catalytic cracking aid, and particularly comprises the following steps: S1, preparing a mixed slurry by adding an IMF structure molecular sieve and an MFI molecular sieve and part of a phosphorus additive; S2, mixing the slurry, metal modified aluminum stone, other inorganic binders and a clay slurry, beating the slurry, and spray drying; S3, after spray drying and forming, introducing the remaining phosphorus additive; and S4, drying and calcining. The phosphorus additive is a phosphorus compound, which can be one or more of phosphorus oxides, phosphoric acid, orthophosphate, phosphite, hypophosphite, alkaline phosphates, acid phosphates and organic compounds containing phosphorus. The catalytic cracking aid can effectively improve the yield and selectivity of propylene and butylene in a catalytic cracking process.

Description

Technical Field

[0001] This invention belongs to the field of materials preparation, specifically relating to a method for preparing a catalytic cracking aid. Background Technology

[0002] The role of additives for producing low-carbon olefins is to increase the yield of low-carbon olefins, especially propylene, in catalytic cracking processes. The most commonly used active component is ZSM-5 molecular sieve. Existing technology discloses a cracking catalyst for producing low-carbon olefins, composed of 0–70% (by weight of catalyst) clay, 5–99% inorganic oxides, and 1–50% zeolite. The zeolite is a mixture of 0–25 wt% REY or high-silica Y-type zeolite and 75–100 wt% phosphorus- and rare-earth-containing five-membered ring high-silica zeolite. This catalyst exhibits higher hydrothermal activity stability, conversion rate, and C2–C4 yield compared to catalysts using ZSM-5 zeolite as the active component.

[0003] Existing technology also discloses a cracking catalyst using phosphorus-modified ZSM-5 zeolite. The preparation of the phosphorus-modified ZSM-5 involves dispersing zeolite in an aqueous solution of a phosphorus-containing compound with a pH above 4.5, loading the zeolite with at least 10 wt% phosphorus (based on P2O5), then slurrying it with a matrix and other zeolite components, followed by spray drying to form the catalyst. The resulting catalyst exhibits a high yield of low-carbon olefins. A catalyst with high zeolite content and high abrasion resistance is also disclosed. This catalyst contains 30–85 wt% ZSM-5 zeolite, 6–24 wt% phosphorus (based on P2O5), and less than 10 wt% Al2O3 and the balance being clay and other components, with the phosphorus present in the matrix. This catalyst, when used in catalytic cracking processes, can increase the yield of light olefins, especially propylene.

[0004] However, the biggest weakness of this type of ZSM-5 molecular sieve is its poor activity stability, which makes it prone to deactivation under the harsh periodic regeneration conditions of FCC devices.

[0005] IM-5 molecular sieve is an IMF (Integrated Mesh Formation) molecular sieve first synthesized by Benazzi in 1998. Its structure was determined by Baerlocher et al. in 2007. This molecular sieve has a two-dimensional ten-membered ring channel structure, with channel diameters similar to those of ZSM-5 molecular sieve, and also possesses a finite channel in the third dimension. Due to its similar channel structure to ZSM-5 molecular sieve, coupled with higher acidity and better hydrothermal stability, it exhibits superior performance in many catalytic reactions. Corma et al. conducted a series of studies on the catalytic performance of IM-5 molecular sieve, finding that it outperforms ZSM-5 molecular sieve in alkane cracking.

[0006] To improve the protection of molecular sieves and enhance the selectivity for low-carbon olefins, the matrix is ​​often modified. Therefore, this invention employs two types of molecular sieves, combined with matrix and catalyst modification techniques, to provide a catalytic cracking aid that increases the concentration of low-carbon olefins in liquefied petroleum gas (LPG) while reducing dry gas and coke production. Summary of the Invention

[0007] To address the aforementioned technical problems, this invention provides a catalytic cracking catalyst additive and its preparation method.

[0008] This invention provides a catalytic cracking additive comprising IMF-structured molecular sieves and MFI molecular sieves, metal-modified alumina, phosphorus additives, other inorganic binders, and clay; based on the dry weight of the additive,

[0009] IMF structured molecular sieves and MFI molecular sieves account for 10-75% by weight;

[0010] Metal-modified alumina accounts for 3-20% by weight, of which the metal, in terms of oxides, accounts for 1-30% by weight of the alumina.

[0011] Phosphorus additives account for 3-35% by weight;

[0012] Other inorganic binders account for 3-20% by weight;

[0013] Clay accounts for 0-60% by weight;

[0014] In this adjuvant 27 In Al MAS NMR, the ratio of the resonance signal peak area with a chemical shift of 40±5ppm to that with a chemical shift of 54ppm±3ppm is 0.1 to 1.

[0015] According to one embodiment of the present invention, the method for preparing the metal-modified aluminum is as follows:

[0016] (1) Add aluminum stone to decationized water and slurry; the solid content of the slurry is preferably 8-15% by weight;

[0017] (2) Choose acidic salts of the metal to dissolve it;

[0018] (3) Add metal salts directly to the aluminum oxide to acidify it;

[0019] (4) Add or not add hydrochloric acid, and control the final colloid pH < 4. Preferably, the pH value is 1.5-3.

[0020] According to one embodiment of the present invention, the metal is selected from at least one of IB, IIB, IVB and VIIIB; preferably, the metal is selected from one or more of Fe, Zr and Cu;

[0021] The metal salt is selected from at least one of chlorides, nitrates, and sulfates.

[0022] According to one embodiment of the present invention, the phosphorus additive is added in two steps.

[0023] According to one embodiment of the present invention, the phosphorus additive is a phosphorus compound. Preferably, the phosphorus additive is one or more of phosphorus oxides, phosphoric acid, orthophosphate, phosphite, hypophosphite, basic phosphate, acid phosphate, and phosphorus-containing organic compounds. More preferably, the phosphorus additive is one or more of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and aluminum phosphate. More preferably, the phosphorus additive is diammonium hydrogen phosphate.

[0024] According to one embodiment of the present invention, the mass ratio of the IMF structured molecular sieve to the MFI molecular sieve is 0.01-100, preferably 0.1-30, and more preferably 0.5-9.

[0025] According to one embodiment of the present invention, the IMF structured molecular sieve is selected from one or more of hydrogen-form IM-5, phosphorus-containing IM-5, and phosphorus- and transition metal-containing IM-5 molecular sieves; the MFI molecular sieve is selected from one or more of hydrogen-form MFI molecular sieves, phosphorus-containing MFI molecular sieves, and phosphorus- and transition metal-containing MFI molecular sieves.

[0026] According to one embodiment of the present invention, the clay is selected from at least one of kaolin, sepiolite, attapulgite, rettoite, montmorillonite, and diatomaceous earth.

[0027] According to one embodiment of the present invention, the other inorganic binder is at least one selected from aluminum sol, aluminosilicate sol, and silica sol.

[0028] This invention provides a method for preparing the above-mentioned auxiliary agent, specifically including the following steps:

[0029] S1. Add some phosphorus additives to the IMF structured molecular sieve and MFI molecular sieve to prepare a mixed slurry;

[0030] S2. Mix the above slurry, the metal-modified alumina, the other inorganic binders and the clay slurry, slurry, and spray dry;

[0031] S3. After spray drying and molding, the remaining phosphorus additives are introduced;

[0032] S4. Drying and roasting.

[0033] According to one embodiment of the present invention, the drying temperature is room temperature to 400°C, preferably 100-300°C; the calcination temperature is 400-700°C, and the calcination time is 0.5-100 hours, preferably 0.5-10 hours.

[0034] According to one embodiment of the present invention, the phosphorus additive added before spraying is 1-10% by weight, and the phosphorus additive added after spraying is 2.1-24% by weight.

[0035] The method of introducing the phosphorus additive after spraying is as follows: at least one phosphorus-containing compound selected from phosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and ammonium phosphate is used to impregnate the catalyst microspheres and / or chemically adsorb the phosphorus compound, and then introduces it through solid-liquid separation (if necessary), drying and calcination processes.

[0036] In the obtained additives, the phosphorus additives added before spraying exist in the form of phosphorus compounds (such as phosphorus oxides, orthophosphates, phosphites, basic phosphates, and acid phosphates). These phosphorus additives can be present in any possible location within the additive, such as inside the pores of the zeolite, on the surface of the zeolite, or in the matrix material; the phosphorus compounds introduced after spraying are mainly present in the matrix material. The types of phosphorus additives added before and after spraying can be the same or different.

[0037] pass 27 Al MAS NMR characterization of the Al coordination state of this additive showed a ratio of 0.1–1 between the resonance peak area at a chemical shift of 40 ± 5 ppm and the resonance peak area at a chemical shift of 54 ± 3 ppm. In the 27Al MAS NMR, the resonance signal at a chemical shift of 54 ± 3 ppm represents a four-coordinated framework aluminum species, while the resonance signal at a chemical shift of 40 ± 3 ppm represents a phosphorus-coordinated framework aluminum species. These characterization results indicate that a two-step phosphorus additive addition can reduce the interaction between phosphorus and the molecular sieve framework aluminum.

[0038] Furthermore, the two-step addition of phosphorus additives also reduces the interaction between phosphorus and the matrix Al.

[0039] The present invention provides a catalytic cracking catalyst, comprising the above-mentioned additives or additives obtained by the above-mentioned preparation method.

[0040] This invention provides a method for preparing metal-modified aluminum, comprising:

[0041] (1) Add aluminum stone to decationized water and slurry; the solid content of the slurry is preferably 8-15% by weight;

[0042] (2) Dissolve the metal in acidic salts;

[0043] (3) Add metal salts directly to the aluminum oxide to acidify it;

[0044] (4) Add or not add hydrochloric acid, and control the final colloid pH < 4. Preferably, the pH value is 1.5 to 3.

[0045] Compared to conventional aluminum oxide aluminate, the metal-modified aluminate prepared by this method reduces the amount of hydrochloric acid used, which is beneficial for improving the activity and stability of the catalytic converter. Beneficial effects: The two-step addition of phosphorus additives and metal-modified aluminate improves the selectivity of the catalyst for low-carbon olefins. The two-step addition reduces the interaction between phosphorus and the matrix AL, thereby simultaneously reducing dry gas and coke production. The catalytic cracking converter provided by this invention, used in the catalytic cracking process, can effectively improve the yield and selectivity of propylene and butene through the synergistic effect between its components.

[0046] The method for preparing metal-modified aluminum provided by this invention involves acidifying aluminum with a metal salt solution to obtain metal-modified aluminum with good performance. It can be used as a catalyst matrix for catalytic cracking and can improve the performance of low-carbon olefins. The metal-modified aluminum can also be used as a catalyst support for other catalysts. Detailed Implementation

[0047] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0048] The method for introducing phosphorus additives after spraying according to the present invention is as follows: at least one phosphorus-containing compound selected from phosphoric acid, ammonium hydrogen phosphate, ammonium dihydrogen phosphate and ammonium phosphate is used to impregnate and / or chemically adsorb phosphorus compounds onto catalyst microspheres, and then introduces the phosphorus compounds through solid-liquid separation (if necessary), drying and calcination processes. The drying temperature can be from room temperature to 400°C, preferably 100-300°C, the calcination temperature can be 400-700°C, preferably 450-650°C, and the calcination time can be 0.5-100 hours, preferably 0.5-10 hours.

[0049] The method for preparing the catalytic cracking additive disclosed herein involves slurrying IMF structured molecular sieves and MFI molecular sieves, and adding a portion of phosphorus additives; mixing inorganic binders, clay, and molecular sieve slurry, and slurrying. There are no special requirements for the order of addition, but preferably, the clay and molecular sieve slurry are mixed first, and then mixed with metal-modified alumina and other inorganic binders and slurryed. This is beneficial to improving the activity and strength of the additive.

[0050] The method for preparing catalytic cracking additives provided in this disclosure further includes a step of spray drying the slurry obtained by pulping. Spray drying methods are well known to those skilled in the art, and this disclosure does not specify any particular method.

[0051] The catalytic cracking additives provided in this disclosure are suitable for various hydrocarbon oil catalytic cracking processes. When used in catalytic cracking processes, they can be added alone to the catalytic cracking reactor or mixed with the catalytic cracking catalyst. Generally, the additives provided in this disclosure account for no more than 30% by weight of the total mixture of FCC catalyst and additives provided in this disclosure, preferably 1-25% by weight, more preferably 3-15% by weight. The hydrocarbon oils are selected from various petroleum fractions, such as crude oil, atmospheric residue, vacuum residue, atmospheric wax oil, vacuum wax oil, straight-run wax oil, propane light / heavy deoiling, coking wax oil, and coal liquefaction products, or one or more of these.

[0052] The catalytic cracking additive disclosed herein is used in the catalytic cracking process, and the hydrocarbon oil catalytic cracking conditions can be conventional catalytic cracking conditions. Generally, the hydrocarbon oil catalytic cracking conditions include a reaction temperature of 400-600℃, preferably 450-550℃, and a weight hourly space velocity of 8-120 h⁻¹. -1 Preferably 8-80 hours -1 The catalyst-to-oil ratio (by weight) is 1-20, preferably 3-15. The catalytic cracking additives provided in this disclosure can be used in various existing catalytic cracking reactors, such as fixed-bed reactors, fluidized-bed reactors, riser reactors, and multi-reaction-zone reactors.

[0053] The present disclosure is further illustrated by the following examples, but the present disclosure is not limited thereto. Unless otherwise specified, the instruments and reagents used in the embodiments of the present disclosure are instruments and reagents commonly used by those skilled in the art.

[0054] When evaluating the performance of the additives disclosed herein in catalytic cracking reactions, an ACE apparatus is used for evaluation.

[0055] For details of the RIPP standard method described in this disclosure, please refer to "Analytical Methods in Petrochemical Industry", edited by Yang Cuiding et al., 1990 edition.

[0056] The properties of some of the raw materials used in the examples are as follows:

[0057] Boehmite is an industrial product manufactured by Shandong Aluminum Company, with a solid content of 60% by weight.

[0058] The aluminum sol is an industrial product produced by Sinopec Catalyst Qilu Branch, with an Al2O3 content of 21.5% by weight.

[0059] The kaolin is a special kaolin for catalytic cracking catalysts produced by Suzhou Kaolin Company, with a solid content of 78% by weight.

[0060] Hydrochloric acid: chemically pure, concentration 36-38% by weight, produced by Beijing Chemical Plant.

[0061] ZRP-5: An industrial product manufactured by Sinopec Catalysts Qilu Branch, with a P2O5 content of 4.12% and a crystallinity of 75%.

[0062] P-IM-5: H-IM-5 molecular sieve was impregnated with a 0.2 mol / L ammonium dihydrogen phosphate solution by stirring for two hours, dried at 120℃ for 10 hours, and calcined at 500℃ for 3 hours to obtain phosphorus-modified IM-5 molecular sieve P-IM-5, which has a P2O5 content of 4.23% by mass and a crystallinity of 78%.

[0063] Example 1 of metal-modified aluminum:

[0064] Add bauxite to decationized water and slurry for 10 min; dissolve FeCl3 and measure pH = 2; add FeCl3 solution directly to bauxite to acidify bauxite; finally add hydrochloric acid to reach a colloidal state and control the final colloid pH = 3 to obtain MAL-1;

[0065] Example 2 of metal-modified aluminum:

[0066] Add the alumina to deionized water and slurry for 10 minutes; dissolve ZrOCl2 and measure the pH = 1; add the ZrOCl2 solution directly to the alumina to acidify it, and control the final colloid pH = 2.5, MAL-2;

[0067] Example 3: Metal-modified aluminum

[0068] Add the alumina to deionized water and slurry for 10 minutes; dissolve CuCl2 and measure the pH to be 1.5; add the CuCl2 solution directly to the alumina to acidify it, and finally add hydrochloric acid to bring it to a colloidal state, controlling the final colloid pH to be 2.5, MAL-3.

[0069] Catalyst Example 1:

[0070] (1) Take molecular sieves P-IM-5 and ZRP-5, add decationized water and slurry for 10 min, add diammonium hydrogen phosphate (a) and slurry for 120 min to obtain molecular sieve slurry; add kaolin, alumina sol and metal-modified alumina to decationized water and slurry for 20 min, add molecular sieve slurry while stirring, add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 min. Spray dry the obtained slurry to obtain microspheres.

[0071] (2) Following the saturated impregnation method, the water absorption rate of the microspheres was measured first. The remaining diammonium hydrogen phosphate (b) was dissolved in water and then slowly added to the microspheres. The mixture was stirred evenly, allowed to stand at room temperature for 4 hours, and then calcined at 500℃ for 2 hours to obtain CAT-1. The ratio is shown in Table 2.

[0072] Examples 2-5: Same steps as Example 1, specific proportions are shown in Table 2.

[0073] Comparative Example 1:

[0074] (1) Take ZRP-5 molecular sieve, kaolin and alumina, add decationized water and alumina sol and slurry for 120 minutes, add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 minutes. Spray dry the obtained slurry to obtain microspheres.

[0075] (2) Following the saturated impregnation method, the water absorption rate of the microspheres was measured first. The remaining diammonium hydrogen phosphate was dissolved in water and then slowly added to the microspheres. The mixture was stirred evenly, allowed to stand at room temperature for 4 hours, and then calcined at 500℃ for 2 hours to obtain DCAT-2. The ratio is shown in Table 1.

[0076] Table 1

[0077]

[0078]

[0079] The following examples use a fixed fluidized bed reactor to illustrate the cracking reaction effect of the cracking aid provided by the present invention.

[0080] The catalytic cracking catalyst SLA, along with 30 grams each of CAT-1~5 and DCAT1~5, were aged for 17 hours at 800℃ under a 100% steam atmosphere. Different amounts of the aged catalyst were mixed with SLA (main properties shown in Table 2), and the catalyst mixtures were loaded into a reactor of a small fixed fluidized bed reactor to catalytically crack the feedstock oil shown in Table 3. Table 4 shows the reaction conditions and results.

[0081] Table 2 Main Properties of SLA

[0082]

[0083] Table 3 Evaluation of Crude Oil Properties

[0084]

[0085]

[0086] Table 4 Evaluation Results

[0087]

[0088]

[0089] As can be seen from Table 4, compared with the reference additive, the catalytic additive provided by the present invention can effectively increase the yield of catalytic cracking liquefied gas, significantly increase the concentration of propylene and butene in catalytic cracking liquefied gas, greatly improve the selectivity of low carbon olefins, and at the same time reduce dry gas and coke.

Claims

1. A catalytic cracking additive, comprising IMF-structured molecular sieves and MFI molecular sieves, metal-modified alumina, phosphorus additives, other inorganic binders, and clay; based on the dry weight of said additive, IMF structured molecular sieves and MFI molecular sieves account for 10-75% by weight; The IMF structured molecular sieve is selected from one or more of hydrogen-form IM-5, phosphorus-containing IM-5, and phosphorus- and transition metal-containing IM-5 molecular sieves; the MFI molecular sieve is selected from one or more of hydrogen-form MFI molecular sieves, phosphorus-containing MFI molecular sieves, and phosphorus- and transition metal-containing MFI molecular sieves. The mass ratio of the IMF-structured molecular sieve to the MFI molecular sieve is 0.1 to 9. The metal-modified alumina accounts for 3-20% by weight, wherein the metal in the metal-modified alumina, calculated as oxide, accounts for 1-30% by weight of the alumina; wherein the metal is one or more selected from Fe, Zr, and Cu; Phosphorus additives account for 3-35% by weight; Other inorganic binders account for 3-20% by weight; Clay accounts for 0-60% by weight; The preparation method of the aforementioned auxiliary agent includes the following steps: S1. Mix the IMF structured molecular sieve and MFI molecular sieve, add some phosphorus additive, and prepare a mixed slurry; S2. Mix the above slurry, the metal-modified alumina, the other inorganic binders and the clay, slurry, and spray dry; S3. After spray drying and molding, the remaining phosphorus additives are introduced; S4. Drying and roasting.

2. The adjuvant according to claim 1, characterized in that, The preparation method of the metal-modified aluminum is as follows: (1) Add aluminum to decationized water and slurry; the solid content of the slurry is 8-15% by weight; (2) Choose acidic salts of the metal to dissolve it; (3) Add metal salts directly to the aluminum oxide to acidify it; (4) Add or not add hydrochloric acid to control the final colloid pH < 4.

3. The adjuvant according to claim 2, characterized in that, The metal salt is selected from at least one of chlorides, nitrates, and sulfates.

4. The adjuvant according to claim 2, characterized in that, The final colloid has a pH value of 1.5-3.

5. The adjuvant according to any one of claims 1-4, characterized in that, The phosphorus additive is a phosphorus compound.

6. The adjuvant according to claim 5, characterized in that, The phosphorus additive is one or more of phosphorus oxides, phosphoric acid, orthophosphate, phosphite, and hypophosphite.

7. The adjuvant according to claim 5, characterized in that, The phosphorus additive is one or more of basic phosphates, acid phosphates, and phosphorus-containing organic compounds.

8. The adjuvant according to claim 5, characterized in that, The phosphorus additive is one or more of phosphoric acid, ammonium phosphate, ammonium dihydrogen phosphate, diammonium hydrogen phosphate, and aluminum phosphate.

9. The adjuvant according to claim 5, characterized in that, The phosphorus additive is diammonium hydrogen phosphate.

10. The adjuvant according to any one of claims 1-4, characterized in that, The mass ratio of the IMF structured molecular sieve to the MFI molecular sieve is 0.5-9.

11. The adjuvant according to any one of claims 1-4, characterized in that, The IMF structured molecular sieve is hydrogen-form IM-5 or phosphorus-containing IM-5; the MFI molecular sieve is hydrogen-form MFI molecular sieve or phosphorus-containing MFI molecular sieve.

12. The adjuvant according to any one of claims 1-4, characterized in that, The clay is selected from at least one of kaolin, sepiolite, attapulgite, rettoite, montmorillonite, and diatomite.

13. The adjuvant according to any one of claims 1-4, characterized in that, The other inorganic binder is at least one selected from aluminum sol, silica-alumina sol, and silica sol.

14. The adjuvant according to any one of claims 1-4, characterized in that, The drying temperature is from room temperature to 400°C; the calcination temperature is 400-700°C, and the calcination time is 0.5-100 hours.

15. The adjuvant according to claim 14, characterized in that, The drying temperature is 100-300℃.

16. The adjuvant according to claim 14, characterized in that, The roasting time is 0.5-10 hours.

17. The adjuvant according to any one of claims 1-4, characterized in that, The phosphorus additive is added at 1-10% by weight before spraying and at 2.1-24% by weight after spraying.

18. A catalytic cracking catalyst comprising the additives according to any one of claims 1-17.

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