A catalytic cracking process and a cracking catalyst comprising a phosphorus-modified ZSM-5 molecular sieve

Abstract

A catalytic cracking catalyst, containing 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder and 2-60% clay by dry basis weight, characterized in that the phosphorus-modified ZSM-5 molecular sieve has a P MAS-NMR spectrum with a resonance signal peak in the chemical shift range of 5 to -20 ppm, and an area ratio of resonance signal peaks with chemical shifts of -30±3 ppm and -40±3 ppm is >1 after hydrothermal aging at 800 DEG C under 100% water vapor for 17 h. 31 In the P MAS-NMR spectrum, the resonance signal peaks have a chemical shift range of 5 to -20 ppm, and an area ratio of resonance signal peaks with chemical shifts of -30±3 ppm and -40±3 ppm is >1 after hydrothermal aging at 800 DEG C under 100% water vapor for 17 h.

Description

Technical Field

[0001] This invention relates to a cracking method and a cracking catalyst, and more specifically to a catalytic cracking method and a cracking catalyst containing Y-type molecular sieves and phosphorus-modified ZSM-5 molecular sieves. Background Technology

[0002] Hydrocarbon cracking at high temperatures converts long-chain hydrocarbons into high-value-added low-carbon olefins such as ethylene and propylene. ZSM-5 molecular sieve (USP3702886), developed by Mobil Petroleum Corporation in the United States, is a high-silica, three-dimensional, straight-channel mesoporous molecular sieve with an MFI structure. Its unique pore structure gives it excellent shape-selective catalysis and isomerization performance. It also features high thermal and hydrothermal stability, high specific surface area, a wide range of silica-to-alumina ratios, unique surface acidity, and low carbon deposition. ZSM-5 molecular sieve is widely used as a catalyst and catalyst support, and has been successfully applied in alkylation, isomerization, disproportionation, catalytic cracking, methanol-to-gasoline, and methanol-to-olefins production processes.

[0003] Since 1983, ZSM-5 molecular sieves have been used as octane enhancers in catalytic cracking processes to improve the octane number and selectivity of low-carbon olefins in catalytic cracked gasoline. US3758403 first reported the use of ZSM-5 as an active component to enhance propylene production, specifically preparing an FCC catalyst using ZSM-5 and REY together as active components. US5997728 disclosed the use of ZSM-5 molecular sieves as an additive to enhance propylene production without any modification to the sieve. Both of these techniques resulted in low propylene yields. While HZSM-5 molecular sieves possess good shape selectivity and isomerization properties, their drawback is poor hydrothermal stability; they are prone to deactivation under harsh high-temperature hydrothermal conditions, leading to reduced catalytic performance.

[0004] In the 1980s, Mobil discovered that phosphorus could improve the hydrothermal stability of ZSM-5 molecular sieves. Furthermore, phosphorus modification of ZSM-5 molecular sieves could selectively convert primary cracking products (such as gasoline olefins) into C3 and C4 olefins, thereby increasing the yield of low-carbon olefins.

[0005] CN 1211469A discloses a five-membered ring molecular sieve composition that produces high yields of propylene and ethylene, comprising 85-95 wt% of a five-membered ring molecular sieve, 2-10 wt% of phosphorus (based on oxides), 0.3-5 wt% of alkaline earth metals (based on oxides), and 0.3-5 wt% of transition metal elements (based on oxides). This composition yields high ethylene yields when used in catalytic thermal cracking reactions.

[0006] US5171921 discloses a phosphorus-modified ZSM-5 molecular sieve with a silicon-to-aluminum ratio of 20-60. After being impregnated with a phosphorus-containing compound and treated with steam at 500-700°C, it exhibits higher activity than untreated HZSM-5 when used in the reaction of converting C3-C20 hydrocarbons into C2-C5 olefins.

[0007] CN102166533A discloses a method for preparing phosphorus-modified ZSM-5 molecular sieves. The method involves adding the molecular sieve to a phosphorus-containing aqueous solution and reacting it for a period of time under specific pH, temperature, and pressure conditions. The resulting product is then filtered, dried, and calcined to obtain the phosphorus-modified molecular sieve. Subsequently, the phosphorus-modified molecular sieve is added to an aqueous solution containing rare earth ions and reacted for a period of time under specific temperature and pressure conditions. This reaction is then followed by filtration, washing, drying, and calcination to obtain a composite modified molecular sieve. Model catalysts prepared using this composite modified molecular sieve exhibit higher hydrothermal stability and micro-activity compared to model catalysts containing unmodified molecular sieves or those modified by other methods.

[0008] CN106994364A discloses a method for preparing phosphorus-modified ZSM-5 molecular sieves. The method involves first mixing one or more phosphorus-containing compounds selected from phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate, and ammonium phosphate with a ZSM-5 molecular sieve containing high alkali metal ions to obtain a mixture with a phosphorus loading of at least 0.1 wt% (based on P2O5). The mixture is then dried, calcined, and subjected to ammonium ion exchange and water washing steps to reduce the alkali metal ion content to below 0.10 wt%. Finally, it undergoes drying and hydrothermal aging at 400-1000℃ under 100% steam conditions. The phosphorus-containing ZSM-5 molecular sieve obtained by this method has a high total acid content, excellent cracking conversion rate and propylene selectivity, and a high liquefied gas yield.

[0009] Although modifying ZSM-5 molecular sieves with organic / inorganic phosphorus compounds can inhibit framework dealuminization and thus improve hydrothermal stability, the introduction of phosphorus species can also regulate the acid center properties of ZSM-5 molecular sieves, thereby improving the cracking conversion rate of long-chain alkanes and the selectivity of low-carbon olefins. However, phosphoric acid or ammonium phosphate salts will generate large molecular phosphoric acid species such as polyphosphoric acid due to dehydration and self-polymerization. These species are prone to accumulate on the outer surface of the molecular sieve, blocking the pores, reducing the pore volume and specific surface area, resulting in low phosphorus-aluminum activation efficiency. Therefore, phosphorus modification cannot achieve the ideal effect of improving hydrothermal stability. Summary of the Invention

[0010] Based on extensive experiments, the inventors discovered that phosphorus-modified ZSM-5 molecular sieves prepared using solid phosphorus-containing compounds with a +1 valence, such as hypophosphoric acid and hypophosphite, as precursors have different physicochemical characteristics from those of molecular sieves prepared by the conventional +5 valence phosphorus source aqueous solution impregnation method. This method can improve the phosphorus-aluminum stabilization efficiency, and the hydrothermal stability, pyrolysis activity, and low-carbon olefin selectivity of the modified ZSM-5 molecular sieve are all improved.

[0011] One objective of this invention is to provide a catalytic cracking method in which one of the active components of the catalyst is a phosphorus-modified ZSM-5 molecular sieve with different physicochemical characteristics from conventional phosphorus-containing ZSM-5 molecular sieves and improved phosphorus-aluminum stabilization efficiency. This method has high cracking conversion rate and high yield of low-carbon olefins and liquefied gas in hydrocarbon catalytic cracking reactions. The second objective is to provide a cracking catalyst used in this cracking method.

[0012] To achieve one of the above objectives, the first aspect of the present invention provides a catalytic cracking method, which involves contacting hydrocarbon oil with a cracking catalyst under catalytic cracking reaction conditions. The cracking catalyst, on a dry basis, contains 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder, and 2-60% clay. The characteristic feature is that the phosphorus-modified ZSM-5 molecular sieve... 31 In the PMAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm.

[0013] To achieve the second objective mentioned above, a second aspect of the present invention provides a pyrolysis catalyst, comprising, on a dry basis by weight, 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder, and 2-60% clay, characterized in that the phosphorus-modified ZSM-5 molecular sieve, 31 In the PMAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm.

[0014] The catalytic cracking method provided by this invention uses a catalyst containing a phosphorus-modified ZSM-5 molecular sieve with specific physicochemical parameters. This phosphorus-modified ZSM-5 molecular sieve is obtained by modifying it with a +1 valent phosphorus source. 31 In the pMAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm. Attached Figure Description

[0015] Figure 1 For phosphorus-modified ZSM-5 molecular sieve samples 31 P MAS-NMR spectrum.

[0016] Figure 2 The phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 PMAS-NMR spectrum.

[0017] Figure 3 For phosphorus-modified ZSM-5 molecular sieve samples 27 Al MAS-NMR spectrum.

[0018] Figure 4 For phosphorus-modified ZSM-5 molecular sieve samples 31 P MAS-NMR spectrum.

[0019] Figure 5 The phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 PMAS-NMR spectrum.

[0020] Figure 6 For phosphorus-modified ZSM-5 molecular sieve samples 27 Al MAS-NMR spectrum.

[0021] Figure 7 For phosphorus-modified ZSM-5 molecular sieve samples 31 P MAS-NMR spectrum.

[0022] Figure 8 The phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 PMAS-NMR spectrum.

[0023] Figure 9 For phosphorus-modified ZSM-5 molecular sieve samples 27 Al MAS-NMR spectrum.

[0024] Figure 10 For phosphorus-modified ZSM-5 molecular sieve samples 31 P MAS-NMR spectrum.

[0025] Figure 11 The phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 PMAS-NMR spectrum.

[0026] Figure 12 For phosphorus-modified ZSM-5 molecular sieve samples 27 Al MAS-NMR spectrum. Detailed Implementation

[0027] The catalytic cracking method provided by this invention involves contacting hydrocarbon oil with a cracking catalyst under catalytic cracking reaction conditions. The cracking catalyst, on a dry basis, contains 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder, and 2-60% clay. The key feature is that the phosphorus-modified ZSM-5 molecular sieve... 31 In the ppm MAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm. The phosphorus-modified ZSM-5 molecular sieve is obtained by modification with a phosphorus-containing compound in which phosphorus has a +1 valence state.

[0028] In the method of this invention, the cracking feedstock can be various hydrocarbon oils. The hydrocarbon oils can be selected from various petroleum fractions, such as crude oil, naphtha, catalytic gasoline, atmospheric residue, vacuum residue, atmospheric wax oil, vacuum wax oil, straight-run wax oil, propane light / heavy deoiling, coking wax oil, and one or more of coal liquefaction products. The hydrocarbon oils may contain heavy metal impurities such as nickel and vanadium, as well as sulfur and nitrogen impurities. For example, the sulfur content in the hydrocarbon oil can be as high as 3.0 wt%, the nitrogen content can be as high as 2.0 wt%, and the content of metallic impurities such as vanadium and nickel can be as high as 3000 ppm.

[0029] In the hydrocarbon oil catalytic cracking method of the present invention, the catalytic cracking conditions can be those conventional in the art, preferably including: a reaction temperature of 500-800°C, for example 550-680°C.

[0030] In the method of this invention, the cracking catalyst can be used alone, that is, added separately to the catalytic cracking reactor, for example, by contacting and reacting the hydrocarbon oil with the catalytic cracking catalyst of this invention under catalytic cracking conditions. Alternatively, the cracking catalyst can be used in a mixture with other conventional cracking catalysts, wherein the cracking catalyst of this invention accounts for no more than 30% by weight of the total mixture, preferably 1-25% by weight, more preferably 3-15% by weight. The other conventional cracking catalysts are well known to those skilled in the art, mainly cracking catalysts with Y-type molecular sieves as the main active component, and will not be described in detail here.

[0031] The pyrolysis catalyst described in the method of this invention contains 2-20% Y-type molecular sieve. The Y-type molecular sieve may be selected from at least one of PSRY molecular sieve, PSRY-S molecular sieve, rare earth-containing PSRY molecular sieve, rare earth-containing PSRY-S molecular sieve, USY molecular sieve, rare earth-containing USY molecular sieve, REY molecular sieve, REHY molecular sieve, and HY molecular sieve.

[0032] The pyrolysis catalyst described in the method of this invention contains 3-80% phosphorus-modified ZSM-5 molecular sieve. The phosphorus-modified ZSM-5 molecular sieve has physicochemical characterization parameters different from those of existing technologies. 31In the phospho-MAS-NMR spectrum, due to the diversity of phosphorus species, the chemical shifts of the resulting resonance signal peaks have a certain range, representing the overall degree of phosphorus species condensation. Resonance signal peaks in the low-field ranges of 0 ppm, -6 ppm, and -15 ppm represent phosphorus species with a lower degree of condensation, such as monomeric phosphate and pyrophosphate, while resonance signal peaks in the range of -20 to -40 ppm represent polyphosphate species with a higher degree of condensation. The inventors of this invention unexpectedly discovered that by using a different calcination method (300–400 ppm with air) than the conventional 550 ℃ calcination method used in the preparation of phosphorus-modified ZSM-5 molecular sieves, the chemical shift range of the resonance signal peaks is 5 to -20 ppm, indicating a lower degree of phosphorus species condensation. In contrast, phosphorus-modified molecular sieves obtained by the conventional 550 ℃ calcination method in the prior art exhibit a higher degree of phosphorus species condensation, with a resonance signal peak chemical shift range of 5 to -50 ppm.

[0033] Furthermore, the phosphorus-modified ZSM-5 molecular sieve described in this invention undergoes hydrothermal aging at 800°C and 100% steam for 17 hours. 31 In the pMAS-NMR spectrum, the ratio of the resonance peak area at a chemical shift of -30±3 ppm to that at a chemical shift of -40±3 ppm is >1, preferably 1.05–1.4, and more preferably 1.1–1.3. The -30±3 ppm resonance signal represents a tetracoordinated phosphorus species formed after stabilizing the framework aluminum species, while the -40±3 ppm resonance signal represents a condensed pentacoordinated phosphorus species. A larger ratio of the -30±3 ppm to -40±3 ppm resonance peak areas indicates a greater number of phosphorus species in the phosphorus-modified molecular sieve that can stabilize the framework aluminum. In existing technologies, the ratio of the -30±3 ppm to -40±3 ppm resonance peak areas in ZSM-5 molecular sieves modified with phosphorus-containing precursors (such as diammonium hydrogen phosphate or phosphoric acid with a +5 valence) is <1.

[0034] Furthermore, the phosphorus-modified ZSM-5 molecular sieve described in this invention undergoes hydrothermal aging at 800°C and 100% steam for 17 hours. 27 In the Al MAS-NMR spectrum, resonance signal peaks with chemical shifts of 39±3 ppm and -12±3 ppm appeared simultaneously. The resonance signal with a chemical shift of 39±3 ppm represents a framework aluminum species stabilized after coordination with a phosphorus species, i.e., a twisted four-coordinate framework aluminum; the resonance signal with a chemical shift of -12±3 ppm represents an extra-framework aluminum species bound to a phosphorus species.

[0035] The phosphorus-modified ZSM-5 molecular sieve described in this invention exhibits a higher phosphorus retention rate after water washing. For example, after washing with hot water at 70°C for 2 hours, the phosphorus content retention rate is higher than 50%, approximately 51-75%. In contrast, the phosphorus content retention rate in existing technologies is less than 50%. The phosphorus content retention rate is defined as the ratio of P2O5 before water washing to P2O5 after water washing, calculated as a percentage by mass.

[0036] The phosphorus-modified ZSM-5 molecular sieve described in this invention has a ratio of phosphorus and aluminum of 0.01 to 5 when both are measured in molar amounts, with a preferred ratio of 0.1 to 3.

[0037] The phosphorus-modified ZSM-5 molecular sieve described in this invention is obtained by modification with a phosphorus-containing compound in which phosphorus has a +1 valence state. In one embodiment, the phosphorus-modified ZSM-5 molecular sieve is obtained by modification with a phosphorus-containing compound in which phosphorus has a +1 valence state and by a step including air calcination at 300-400°C. The modification includes two methods: impregnation with an aqueous solution of a phosphorus precursor in which +1 valence phosphorus is present and heat melting treatment.

[0038] In one more specific embodiment, the phosphorus-modified ZSM-5 molecular sieve can be obtained by contacting and impregnating HZSM-5 molecular sieve with an aqueous solution of a phosphorus-containing compound with a phosphorus oxidation state of +1, followed by drying and calcination in air at 300–400°C. In the impregnation, the water-to-sieve weight ratio is 0.5–2, and the process lasts for 0.5–10 hours. The drying is carried out in an air atmosphere at 100–120°C for 2–24 hours. The calcination is carried out in an air atmosphere at 300–400°C, preferably 330–370°C, and more preferably 350°C for 0.5–12 hours.

[0039] In a more specific embodiment, the mixture obtained by grinding HZSM-5 molecular sieve with a solid phosphorus-containing compound in the +1 oxidation state of phosphorus can be heated and melted, then cooled to 20-25°C and calcined at 300-400°C. During the heating and melting process, the temperature is higher than the melting point of the solid phosphorus-containing compound but lower than the temperature at which the solid phosphorus-containing compound decomposes or dehydrates (e.g., hypophosphoric acid has a melting point of 26.5°C and a decomposition temperature of 130°C), and the treatment time is 2-72 hours.

[0040] Treating HZSM-5 molecular sieves with phosphorus-containing compounds having a +1 valence state accelerates the migration of phosphorus species into the pores of the ZSM-5 molecular sieve by selecting a relatively small +1 valence phosphorus source, thereby increasing the activation efficiency of phosphorus-aluminum species. The phosphorus-containing compounds having a +1 valence state include one or more of hypophosphorous acid, ammonium hypophosphorus, and hypophosphite; or, the aqueous solution of the phosphorus-containing compounds having a +1 valence state is obtained by adjusting the pH of an aqueous solution of hypophosphorous acid to 5-9 with ammonia. These serve as phosphorus-containing precursors, and after air calcination at 300-400℃, especially 350℃, the phosphorus valence state is converted to a higher oxidation state, providing the conditions for stabilizing the skeletal aluminum framework during aging.

[0041] Regarding the phosphorus-modified ZSM-5 molecular sieve involved in this application, this application also incorporates the contents of Chinese Invention Application No. 202310788556.0, filed on June 30, 2023, for reference.

[0042] In the method of the present invention, the pyrolysis catalyst preferably comprises 6-85% by dry weight of the Y-type molecular sieve and the phosphorus-modified ZSM-5 molecular sieve. Further, the Y-type molecular sieve comprises 3-15% by dry weight of the pyrolysis catalyst, and the phosphorus-modified molecular sieve comprises 5-75% by dry weight of the pyrolysis catalyst. More preferably, the weight ratio of the Y-type molecular sieve to the phosphorus-modified ZSM-5 molecular sieve is 1:(0.25-40).

[0043] In the cracking catalyst used in the method of the present invention, the inorganic binder includes a phosphorus-aluminum inorganic binder, which comprises 5-40% by weight on a dry basis of the catalyst. Based on the dry weight of the phosphorus-aluminum inorganic binder, the phosphorus-aluminum inorganic binder comprises 15-40% by weight of aluminum component based on Al2O3 and 45-80% by weight of phosphorus component based on P2O5, and its P / Al weight ratio is 1.0-6.0, pH value is 1-3.5, and solid content is 15-60% by weight; for example, it comprises 15-40% by weight of aluminum component based on Al2O3 and 45-80% by weight of phosphorus component based on P2O5; preferably, it contains 15-35% by weight of aluminum component based on Al2O3 and 50-75% by weight of phosphorus component based on P2O5, and its P / Al weight ratio is preferably 1.2-6.0, more preferably 2.0-5.0, and pH value is preferably 1.5-3.0. Preferably, the phosphorus-aluminum inorganic binder, based on its dry weight, comprises 20-40% by weight of aluminum (Al2O3) and 60-80% by weight of phosphorus (P2O5). The phosphorus-aluminum inorganic binder can be prepared by the following steps: dispersing an alumina source, clay (e.g., borax, kaolin) with water into a slurry with a solid content of 5-50% by weight; wherein the alumina source is acid-soluble aluminum hydroxide and / or alumina (e.g., boehmite, SB powder, γ-alumina), relative to 15-50 parts by weight of the alumina source (based on Al2O3); adding concentrated phosphoric acid to the slurry under stirring at a P / Al weight ratio of 1-6, and reacting the resulting mixed slurry at 50-99°C for 15-90 minutes; wherein in the P / Al ratio, P is the weight of phosphorus in the phosphoric acid (based on elemental content), and Al is the weight of aluminum in the alumina source (based on elemental content).

[0044] In the pyrolysis catalyst used in the method of the present invention, the inorganic binder may also contain at least one selected from boehmite, aluminum sol, silica-alumina sol and water glass.

[0045] In the pyrolysis catalyst used in the method of the present invention, the clay is well known to those skilled in the art. The clay can be at least one selected from kaolin, sepiolite, attapulgite, palygorskite, montmorillonite, and diatomaceous earth, preferably kaolin, metakaolin, or palygorskite. Based on the dry weight of the catalytic pyrolysis catalyst, it contains 2-60% clay, preferably 5-55% clay, and more preferably 15-40% clay.

[0046] In one specific preparation embodiment of the cracking catalyst used in the method of the present invention, an inorganic binder (e.g., boehmite, alumina sol, silica sol, aluminosilicate gel, or a mixture of two or more thereof) is mixed with clay (e.g., kaolin) and water (e.g., deoxygenated water and / or deionized water) to prepare a slurry with a solid content of 10-50% by weight. The mixture is stirred evenly, and the pH of the slurry is adjusted to 1-4 with an inorganic acid such as hydrochloric acid, nitric acid, phosphoric acid, or sulfuric acid. The pH is maintained, and the mixture is allowed to age at 20-80°C for 0-2 hours, for example, 0.3-2 hours. Then, alumina sol and / or silica sol are added, and the mixture is stirred for 0.5-1.5 hours to form a colloid. Then, molecular sieves, including the phosphorus-modified ZSM-5 molecular sieve and Y-type molecular sieve, are added to form a catalyst slurry with a solid content of, for example, 20-45% by weight. After further stirring, the mixture is spray-dried to prepare microsphere catalysts. The microsphere catalyst is then calcined, for example at 350–650°C or 400–600°C, preferably 450–550°C, for 0.5–6 hours or 0.5–2 hours. It is then washed with ammonium sulfate (the washing temperature can be 40–70°C, and the weight ratio of ammonium sulfate:microsphere catalyst:water is 0.2–0.8:1:5–15) until the sodium oxide content is less than 0.25% by weight. After washing with water and filtering, it is then dried.

[0047] In another specific preparation embodiment of the cracking catalyst used in the method of the present invention, Y-type molecular sieve and phosphorus-modified ZSM-5 molecular sieve, phosphorus aluminum inorganic binder and other inorganic binders can be mixed, clay can be added, pulping can be carried out, and spray drying can be performed.

[0048] This invention further provides a pyrolysis catalyst for the above-described pyrolysis method, comprising, on a dry weight basis, 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder, and 2-60% clay, wherein the phosphorus-modified ZSM-5 molecular sieve... 31 In the ppm MAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm. This phosphorus-modified ZSM-5 molecular sieve is obtained by modifying phosphorus-containing compounds with phosphorus in the +1 oxidation state and calcining in air at 300 to 400 °C.

[0049] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0050] X-ray diffraction (XRD) patterns were determined using a Rigaku TTR-3 powder X-ray diffractometer. Instrument parameters: copper target (tube voltage 40 kV, tube current 250 mA), scintillation counter, step width 0.02°, scan rate 0.4 (°) / min. ZSM-5 molecular sieve synthesized using the method in Example 1 of CN1056818C was used as a standard, and its crystallinity was defined as 100%. Relative crystallinity was expressed as a percentage, representing the sum of the peak areas of the five characteristic diffraction peaks between 2θ and 25.0° in the X-ray diffraction patterns of the obtained product and the standard.

[0051] 31 P MAS-NMR spectral analysis was performed using a Bruker AVANCE III 600WB spectrometer. Instrument parameters: rotor diameter 4 mm, resonance spectrum 202.4 MHz, pulse width 0.4 μs (corresponding to a 15° chamfer), magic angle rotation speed 10 kHz. 31 The peak areas of the P MAS-NMR spectrum, with a chemical shift of -30±3ppm and -40±3ppm, were calculated by peak fitting.

[0052] 27 Al MAS-NMR spectral analysis was performed using a Bruker AVANCE III 600WB spectrometer. Instrument parameters: rotor diameter 4 mm, resonance spectrum 156.4 MHz, pulse width 0.4 μs (corresponding to a 15° chamfer), magic angle rotation speed 12 kHz, and delay time 1 s. 27 The Al MAS-NMR spectrum features a characteristic peak at 39±3 ppm, which is attributed to phosphorus-stable framework aluminum (twisted four-coordinate framework aluminum). The full width at half maximum (FWHM) of this characteristic peak is calculated by fitting the peaks.

[0053] X-ray photoelectron spectroscopy (XPS) was used for the analysis of phosphorus species on the surface of molecular sieves. The valence state changes of phosphorus compounds loaded on phosphorus-modified molecular sieves after drying and calcination were investigated using a Thermo Fisher-VG ESCALAB 250 X-ray photoelectron spectrometer. Instrument parameters: The excitation source was monochromatic AlKα X-rays with a power of 150 W; the charge shift was corrected using the C1s peak (284.8 eV) from contaminating carbon.

[0054] Unless otherwise specified, the instruments and reagents used in the embodiments of the present invention are instruments and reagents commonly used by those skilled in the art.

[0055] The properties of some of the raw materials used in the examples are as follows:

[0056] Boehmite is an industrial product manufactured by Shandong Aluminum Company, with a solid content of 60% by weight.

[0057] The aluminum sol is an industrial product manufactured by Sinopec Catalysts Shandong Branch, with an Al2O3 content of 21.5% by weight.

[0058] The silica sol is an industrial product manufactured by Sinopec Catalysts Qilu Branch, with a SiO2 content of 28.9% by weight and a Na2O content of 8.9%.

[0059] The kaolin is a special kaolin for catalytic cracking catalysts produced by Suzhou Kaolin Company, with a solid content of 78% by weight. The rettosite is produced by Hubei Zhongxiang Mingliu Rettosite Development Co., Ltd., with a quartz sand content of <3.5% by weight, an Al2O3 content of 39.0% by weight, a Na2O content of 0.03% by weight, and a solid content of 77% by weight.

[0060] SB aluminum hydroxide powder, manufactured by Condex GmbH, Germany, has an Al2O3 content of 75% by weight.

[0061] HRY molecular sieve is an industrial product manufactured by Sinopec Catalyst Changling Branch, with a rare earth content of 10% by weight.

[0062] PSRY molecular sieve is an industrial product manufactured by Sinopec Catalyst Changling Branch. It has a Na2O content of <1.5 wt%, a P2O5 content of 0.8-1.2 wt%, a cell constant of <2.456 nm, and a crystallinity of ≥64%.

[0063] Unless otherwise specified, the instruments and reagents used in the embodiments of the present invention are instruments and reagents commonly used by those skilled in the art.

[0064] Examples 1-8 illustrate the preparation and characterization of the phosphorus-modified ZSM-5 molecular sieve used in this invention.

[0065] Example 1

[0066] 6.9 g of hypophosphoric acid was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 350 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve sample was designated as TCB-1.

[0067] Example 2

[0068] 6.9g of solid hypophosphoric acid was added to 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30), and the mixture was ground and mixed for 0.5h. The mixture was then transferred to a Teflon-lined stainless steel high-pressure reactor for a melting process at 40℃ for 10h. After the melting process, the sample was allowed to cool to room temperature naturally before being removed. The sample was then calcined at 350℃ for 2h to obtain a phosphorus-containing ZSM-5 molecular sieve sample, denoted as TRCB-1.

[0069] Comparative Example 1

[0070] 13.9g of diammonium hydrogen phosphate was dissolved in 145g of deionized water at 25℃ and stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30) was added and modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. Then, it was calcined in an air atmosphere in a muffle furnace at 550℃ for 2h. The resulting phosphorus-containing ZSM-5 molecular sieve control sample was designated as DPB-1.

[0071] Comparative Example 2

[0072] 12.1 g of phosphoric acid solution (85 wt%) was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 550 °C for 2 h. The resulting phosphorus-containing ZSM-5 molecular sieve control sample was designated as DPB-2.

[0073] Comparative Example 3

[0074] 6.9 g of hypophosphoric acid was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 550 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve sample was designated JCB-1.

[0075] Phosphorus-modified ZSM-5 molecular sieve samples TCB-1 and TRCB-1, and control samples DPB-1, DPB-2, and JCB-1 31 The pMAS-NMR spectrum is shown below. Figure 1 . Figure 1In the study, the characteristic peaks with chemical shifts at 0 ppm, -6 ppm, and -15 ppm belong to oligophosphoric acid species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm belong to polyphosphoric acid species.

[0076] Phosphorus-modified ZSM-5 molecular sieve samples TCB-1 and TRCB-1, and control samples DPB-1, DPB-2, and JCB-1 were subjected to hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 The pMAS-NMR spectrum is shown below. Figure 2 . Figure 2 In the table, the resonance signal with a chemical shift of -30±3ppm represents the tetracoordinated phosphorus species formed after the stabilization of the framework aluminum species, and the resonance signal with a chemical shift of -40±3ppm represents the condensation-polymerized pentacoordinated phosphorus species. The ratio of the peak area of ​​the -30±3ppm signal to that of the -40±3ppm signal is shown in Table 1.

[0077] Phosphorus-modified ZSM-5 molecular sieve samples TCB-1 and TRCB-1, and control samples DPB-1, DPB-2, and JCB-1 27 The Al MAS-NMR spectrum is shown below. Figure 3 .

[0078] The relative crystallinity and crystal retention of phosphorus-modified ZSM-5 molecular sieve samples TCB-1 and TRCB-1, and control samples DPB-1, DPB-2, and JCB-1 before and after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours are shown in Table 2.

[0079] The phosphorus content retention rates of phosphorus-modified ZSM-5 molecular sieve samples TCB-1 and TRCB-1, and control samples DPB-1, DPB-2, and JCB-1 after washing with water are shown in Table 3.

[0080] Table 1

[0081] sample -30±3ppm / -40±3ppm signal peak area ratio TCB-1 1.2 TRCB-1 1.1 DPB-1 0.6 DPB-2 0.7 JCB-1 0.7

[0082] Table 2

[0083]

[0084] Table 3

[0085] sample Phosphorus content retention rate / % TCB-1 62 TRCB-1 61 DPB-1 45 DPB-2 48 JCB-1 49

[0086] Example 3

[0087] 3.45 g of hypophosphoric acid was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 350 °C for 2 h. The resulting phosphorus-containing ZSM-5 molecular sieve sample was designated as TCB-2.

[0088] Example 4

[0089] 3.45g of solid hypophosphoric acid was added to 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30), and the mixture was ground and mixed for 0.5h. The mixture was then transferred to a Teflon-lined stainless steel high-pressure reactor for a melting process at 40℃ for 10h. After the melting process, the sample was allowed to cool to room temperature naturally before being removed. The sample was then calcined at 350℃ for 2h to obtain a phosphorus-modified ZSM-5 molecular sieve sample, denoted as TRCB-2.

[0090] Comparative Example 4

[0091] 6.95g of diammonium hydrogen phosphate was dissolved in 145g of deionized water at 25℃ and stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30) was added, and the solution was modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. The solution was then calcined in an air atmosphere in a muffle furnace at 550℃ for 2h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated as DPB-3.

[0092] Comparative Example 5

[0093] 6.05 g of phosphoric acid solution (85 wt%) was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 550 °C for 2 h to obtain a phosphorus-modified ZSM-5 molecular sieve control sample, denoted as DPB-4.

[0094] Comparative Example 6

[0095] 3.45 g of hypophosphoric acid was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 550 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated JCB-2.

[0096] Phosphorus-modified ZSM-5 molecular sieve samples TCB-2 and TRCB-2, and control samples DPB-3, DPB-4, and JCB-2 31 The pMAS-NMR spectrum is shown below. Figure 4 . Figure 4 In the study, the characteristic peaks with chemical shifts at 0 ppm, -6 ppm, and -15 ppm belong to oligophosphoric acid species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm belong to polyphosphoric acid species.

[0097] Phosphorus-modified ZSM-5 molecular sieve samples TCB-2 and TRCB-2, and control samples DPB-3, DPB-4, and JCB-2 were subjected to hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 The pMAS-NMR spectrum is shown below. Figure 5 . Figure 5 In the table, the resonance signal with a chemical shift of -30±3ppm represents the tetracoordinated phosphorus species formed after the stabilization of the framework aluminum species, and the resonance signal with a chemical shift of -40±3ppm represents the condensation-polymerized pentacoordinated phosphorus species. The peak area ratio of the -30±3ppm / -40±3ppm signals is shown in Table 4.

[0098] Figure 6 for 27 Al MAS-NMR spectrum.

[0099] The relative crystallinity and crystal retention of phosphorus-modified ZSM-5 molecular sieve samples TCB-2 and TRCB-2, and control samples DPB-3, DPB-4, and JCB-2 before and after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours are shown in Table 5.

[0100] The phosphorus content retention rates of phosphorus-modified ZSM-5 molecular sieve samples TCB-2 and TRCB-2, and control samples DPB-3, DPB-4, and JCB-2 after washing with water are shown in Table 6.

[0101] Table 4

[0102] sample -30±3ppm / -40±3ppm signal peak area ratio TCB-2 1.3 TRCB-2 1.2 DPB-3 0.7 DPB-4 0.7 JCB-2 0.8

[0103] Table 5

[0104]

[0105] Table 6

[0106] sample Phosphorus content retention rate / % TCB-2 70 TRCB-2 71 DPB-3 48 DPB-4 46 JCB-2 47

[0107] Example 5

[0108] 10.35g of hypophosphoric acid was dissolved in 145g of deionized water at 25℃. Ammonia was added to adjust the pH of the solution to be within the range of 5-9. The solution was stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30) was added, and the solution was modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. The solution was then calcined in an air atmosphere in a muffle furnace at 350℃ for 2h. The resulting phosphorus-modified ZSM-5 molecular sieve sample was designated as TCB-3.

[0109] Example 6

[0110] 13.02g of ammonium hypophosphite was added to 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30), and the mixture was ground and mixed for 0.5h. The mixture was then transferred to a Teflon-lined stainless steel high-pressure reactor for a melting process at 40℃ for 10h. After the melting process, the sample was allowed to cool to room temperature naturally before being removed. The sample was then calcined at 350℃ for 2h to obtain a phosphorus-modified ZSM-5 molecular sieve sample, denoted as TRCB-3.

[0111] Comparative Example 7

[0112] 20.85g of diammonium hydrogen phosphate was dissolved in 145g of deionized water at 25℃ and stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30) was added, and the solution was modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. The solution was then calcined in an air atmosphere in a muffle furnace at 550℃ for 2h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated as DPB-5.

[0113] Comparative Example 8

[0114] 18.15 g of phosphoric acid solution (85 wt%) was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 550 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated as DPB-6.

[0115] Comparative Example 9

[0116] 10.35g of hypophosphoric acid was dissolved in 145g of deionized water at 25℃. Ammonia was added to adjust the pH of the solution to be within the range of 5-9. The solution was stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=30) was added, and the solution was modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. The solution was then calcined in an air atmosphere in a muffle furnace at 550℃ for 2h to obtain a phosphorus-modified ZSM-5 molecular sieve control sample, denoted as JCB-4.

[0117] Phosphorus-modified ZSM-5 molecular sieve samples TCB-3 and TRCB-3, and control samples DPB-5, DPB-6, and JCB-4 31 The pMAS-NMR spectrum is shown below. Figure 7 . Figure 7 In the study, the characteristic peaks with chemical shifts at 0 ppm, -6 ppm, and -15 ppm belong to oligophosphoric acid species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm belong to polyphosphoric acid species.

[0118] Phosphorus-modified ZSM-5 molecular sieve samples TCB-3 and TRCB-3, and control samples DPB-5, DPB-6, and JCB-4 were subjected to hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 The pMAS-NMR spectrum is shown below. Figure 8 . Figure 8 In the table, the resonance signal with a chemical shift of -30±3ppm represents the tetracoordinated phosphorus species formed after the stabilization of the framework aluminum species, and the resonance signal with a chemical shift of -40±3ppm represents the pentacoordinated phosphorus species formed by condensation. The peak area ratio of the -30±3ppm / -40±3ppm signals is shown in Table 7.

[0119] Figure 9 for 27 Al MAS-NMR spectrum.

[0120] The relative crystallinity and crystal retention of phosphorus-modified ZSM-5 molecular sieve samples TCB-3 and TRCB-3, and control samples DPB-5, DPB-6, and JCB-4 before and after hydrothermal aging treatment at 800℃ and 100% steam for 17 hours are shown in Table 8.

[0121] The phosphorus content retention rates of phosphorus-modified ZSM-5 molecular sieve samples TCB-3, TRCB-3, and control samples DPB-5, DPB-6, and JCB-4 after washing with water are shown in Table 9.

[0122] Table 7

[0123] sample -30±3ppm / -40±3ppm signal peak area ratio TCB-3 1.2 TRCB-3 1.2 DPB-5 0.7 DPB-6 0.8 JCB-4 0.8

[0124] Table 8

[0125]

[0126] Table 9

[0127] sample Phosphorus content retention rate / % TCB-3 58 TRCB-3 55 DPB-5 42 DPB-6 41 JCB-4 45

[0128] Example 7

[0129] 1.36 g of ammonium hypophosphite was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 100) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 350 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve sample was designated as TCB-4.

[0130] Comparative Example 10

[0131] 2.16g of diammonium hydrogen phosphate was dissolved in 145g of deionized water at 25℃ and stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=100) was added, and the mixture was modified by impregnation. After impregnation at 25℃ for 0.5h, it was transferred to an oven and dried at 120℃ for 12h. Then, it was calcined in an air atmosphere in a muffle furnace at 550℃ for 2h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated as DPB-7.

[0132] Comparative Example 11

[0133] 1.36 g of ammonium hypophosphate was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 100) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 550 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated JCB-5.

[0134] Example 8

[0135] 0.91 g of ammonium hypophosphate was dissolved in 145 g of deionized water at 25 °C and stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 150) was added, and the solution was modified by impregnation. After impregnation at 25 °C for 0.5 h, the solution was transferred to an oven and dried at 120 °C for 12 h. The solution was then calcined in an air atmosphere in a muffle furnace at 350 °C for 2 h. The resulting phosphorus-modified ZSM-5 molecular sieve sample was designated as TCB-5.

[0136] Comparative Example 12

[0137] 1.45g of diammonium hydrogen phosphate was dissolved in 145g of deionized water at 25℃ and stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=150) was added, and the solution was modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. The solution was then calcined in an air atmosphere in a muffle furnace at 550℃ for 2h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated as DPB-8.

[0138] Comparative Example 13

[0139] 0.91g of ammonium hypophosphate was dissolved in 145g of deionized water at 25℃ and stirred for 0.5h to obtain a phosphorus-containing aqueous solution. 100g of HZSM-5 molecular sieve (nSiO2 / nAl2O3=150) was added, and the solution was modified by impregnation. After impregnation at 25℃ for 0.5h, the solution was transferred to an oven and dried at 120℃ for 12h. The solution was then calcined in an air atmosphere in a muffle furnace at 550℃ for 2h. The resulting phosphorus-modified ZSM-5 molecular sieve control sample was designated JCB-6.

[0140] Phosphorus-modified ZSM-5 molecular sieve sample TCB-4, control sample DPB-7, control sample JCB-5, sample TCB-5, control sample DPB-8, and control sample JCB-6 31 The pMAS-NMR spectrum is shown below. Figure 10 . Figure 10 In the study, the characteristic peaks with chemical shifts at 0 ppm, -6 ppm, and -15 ppm belong to oligophosphoric acid species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm belong to polyphosphoric acid species.

[0141] Phosphorus-modified ZSM-5 molecular sieve sample TCB-4, control sample DPB-7, control sample JCB-5, sample TCB-5, control sample DPB-8, and control sample JCB-6 were subjected to hydrothermal aging treatment at 800℃ and 100% steam for 17 hours. 31 The pMAS-NMR spectrum is shown below. Figure 11 . Figure 11In the table, the resonance signal with a chemical shift of -30±3ppm represents the tetracoordinated phosphorus species formed after the stabilization of the framework aluminum species, and the resonance signal with a chemical shift of -40±3ppm represents the pentacoordinated phosphorus species formed by condensation. The peak area ratio of the -30±3ppm / -40±3ppm signals is shown in Table 10.

[0142] Figure 12 for 27 Al MAS-NMR spectrum.

[0143] The relative crystallinity and crystal retention of phosphorus-modified ZSM-5 molecular sieve sample TCB-4, control sample DPB-7, control sample JCB-5, sample TCB-5, control sample DPB-8, and control sample JCB-6 before and after hydrothermal aging treatment at 800℃ and 100% steam for 17h are shown in Table 11.

[0144] The phosphorus content retention rates of phosphorus-modified ZSM-5 molecular sieve samples TCB-4, DPB-7, JCB-5, TCB-5, DPB-8, and JCB-6 after washing with water are shown in Table 12.

[0145] Table 10

[0146] sample -30±3ppm / -40±3ppm signal peak area ratio TCB-4 1.2 DPB-7 0.7 JCB-5 0.8 TCB-5 1.1 DPB-8 0.7 JCB-6 0.7

[0147] Table 11

[0148]

[0149] Table 12

[0150] sample Phosphorus content retention rate / % TCB-4 73 DPB-7 45 JCB-5 47 TCB-5 72 DPB-8 44 JCB-6 43

[0151] Examples 9-16 illustrate the preparation of the cracking catalyst provided by the present invention.

[0152] The phosphorus aluminum inorganic binders NJ1 and NJ2 used in the examples were prepared using the following process:

[0153] 1. NJ1: 1.91 kg of boehmite (containing 1.19 kg of Al2O3), 0.56 kg of kaolin (0.5 kg on a dry basis), and 3.27 kg of decationized water were mixed into a slurry for 30 minutes. While stirring, 5.37 kg of concentrated phosphoric acid (85% by mass) was added to the slurry at a rate of 0.04 kg phosphoric acid / min / kg alumina source. The temperature was raised to 70°C, and the mixture was reacted at this temperature for 45 minutes to obtain the phosphorus-aluminum inorganic binder. The material ratio is shown in Table 13, and the sample number is NJ1.

[0154] 2. NJ2: Following the preparation process of NJ1, the material ratio is shown in Table 13, and the sample number is NJ2.

[0155] Table 13

[0156]

[0157] Examples 9-10

[0158] Take the phosphorus-modified ZSM-5 molecular sieve sample TCB-1, Y-type molecular sieve (PSRY molecular sieve), kaolin, and pseudoboehmite from Example 1, add decationized water and slurry for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 minutes. Then add phosphorus-aluminum inorganic binder NJ1, stir for 30 minutes, and spray dry the obtained slurry to obtain microspheres. Calcine the microspheres at 500°C for 1 hour to obtain the cracking catalyst, designated Cat1.

[0159] The phosphorus-modified ZSM-5 molecular sieve sample TCB-1 of Example 1 was replaced with the phosphorus-modified ZSM-5 molecular sieve sample TRCB-1 of Example 2, and the same preparation process as described above was used to prepare the cracking catalyst, which was numbered Cat2.

[0160] In the material ratio of Cat1 and Cat2, on a dry basis, phosphorus-modified ZSM-5 molecular sieve accounts for 60%, PSRY accounts for 5%, kaolin accounts for 20%, phosphorus aluminum binder NJ1 accounts for 10%, and pseudoboehmite accounts for 5%.

[0161] Comparative Examples 14, 15, and 16

[0162] The preparation process and material ratio were the same as in Example 9, except that the phosphorus-modified ZSM-5 molecular sieve comparative samples DPB-1, DPB-2 and JCB-1 of Comparative Examples 1, 2 and 3 were used to replace the phosphorus-modified ZSM-5 molecular sieve sample TCB-1, respectively, to prepare comparative cracking catalysts, which were numbered DCat1, DCat2 and DCat3.

[0163] Examples 11-12

[0164] Take the phosphorus-modified molecular sieve TCB-2, Y-type molecular sieve (HRY molecular sieve), and kaolin from Example 3, add decationized water and aluminum sol, and slurry for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 minutes. Then add phosphorus-aluminum inorganic binder NJ2, stir for 30 minutes, and spray dry the obtained slurry to obtain microspheres. Calcine the microspheres at 500°C for 1 hour to obtain the cracking catalyst, designated Cat3.

[0165] Using the phosphorus-modified molecular sieve TRCB-2 from Example 4 instead of molecular sieve TCB-2, and following the same preparation process as described above, cracking catalysts were prepared, designated Cat4.

[0166] In the material ratio of the cracking catalysts Cat3 and Cat4, on a dry basis, phosphorus-modified ZSM-5 molecular sieve accounts for 60%, HRY accounts for 5%, kaolin accounts for 20%, phosphorus-aluminum binder NJ2 accounts for 10%, and aluminum sol accounts for 5%.

[0167] Comparative Examples 17, 18, and 19

[0168] The preparation process and material ratio were the same as in Example 11, except that phosphorus-modified molecular sieves DPB-3, DPB-4, and JCB-2 from Comparative Examples 4, 5, and 6 were used to replace molecular sieve TCB-2. Comparative cracking catalysts were prepared and labeled DCat4, DCat5, and DCat6, respectively.

[0169] Examples 13-14

[0170] Take the phosphorus-modified ZSM-5 molecular sieve sample TCB-3, Y-type molecular sieve (PSRY molecular sieve), and kaolin from Example 5, add decationized water and aluminum sol, and slurry for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 minutes. Then add phosphorus-aluminum inorganic binder NJ2, stir for 30 minutes, and spray dry the obtained slurry to obtain microspheres. Calcine the microspheres at 500°C for 1 hour to obtain the cracking catalyst, designated Cat5.

[0171] The phosphorus-modified molecular sieve TRCB-3 from Example 6 was used to replace molecular sieve TCB-3, and the same preparation process as described above was used to prepare a cracking catalyst, designated Cat6.

[0172] In the material ratio of the cracking catalysts Cat5 and Cat6, on a dry basis, phosphorus-modified ZSM-5 molecular sieve accounts for 60%, PSRY accounts for 5%, kaolin accounts for 20%, phosphorus-aluminum binder NJ2 accounts for 10%, and aluminum sol accounts for 5%.

[0173] Comparative Examples 20, 21, and 22

[0174] The preparation process and material ratios were the same as in Example 13, except that phosphorus-modified ZSM-5 molecular sieves DPB-5, DPB-6, and JCB-4 of Comparative Examples 7, 8, and 9 were used to replace molecular sieve TCB-3. Comparative cracking catalysts were prepared and numbered DCat7, DCat8, and DCat9, respectively.

[0175] Example 15

[0176] Take the phosphorus-modified molecular sieve TCB-4, Y-type molecular sieve (PSRY-S molecular sieve), and kaolin from Example 7, add decationized water and aluminum sol, and slurry for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 minutes. Then add phosphorus-aluminum inorganic binder NJ1, stir for 30 minutes, and spray dry the obtained slurry to obtain microspheres. Calcine the microspheres at 500°C for 1 hour to obtain the cracking catalyst, designated Cat7.

[0177] In the material composition of the cracking catalyst Cat7, on a dry basis, phosphorus-modified ZSM-5 molecular sieve accounts for 60%, PSRY-S accounts for 5%, kaolin accounts for 20%, phosphorus-aluminum binder NJ1 accounts for 10%, and aluminum sol accounts for 5%.

[0178] Comparative Examples 23 and 24

[0179] The preparation process and material ratio were the same as in Example 15, except that the phosphorus-modified ZSM-5 molecular sieves DPB-7 and JCB-5 of Comparative Examples 10 and 11 were used to replace TCB-4 to prepare comparative cracking catalysts, numbered DCat10 and DCat11 respectively.

[0180] Example 16

[0181] Take the phosphorus-modified ZSM-5 molecular sieve sample TCB-5, Y-type molecular sieve (HRY molecular sieve), and kaolin from Example 8, add decationized water and aluminum sol, and slurry for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH of the slurry to 3.0, and then continue slurrying for 45 minutes. Then add phosphorus-aluminum inorganic binder NJ1, stir for 30 minutes, and spray dry the obtained slurry to obtain microspheres. Calcine the microspheres at 500°C for 1 hour to obtain the cracking catalyst, designated Cat8.

[0182] In the material composition of the cracking catalyst Cat8, on a dry basis, phosphorus-modified ZSM-5 molecular sieve accounts for 60%, HRY accounts for 5%, kaolin accounts for 20%, phosphorus-aluminum binder NJ1 accounts for 10%, and aluminum sol accounts for 5%.

[0183] Comparative Examples 25 and 26

[0184] The preparation process and material ratio were the same as in Example 16, except that the phosphorus-modified ZSM-5 molecular sieves DPB-8 and JCB-6 of Comparative Examples 12 and 13 were used to replace TCB-5, respectively, to prepare comparative cracking catalysts, numbered DCat12 and DCat13.

[0185] The following examples illustrate the catalytic cracking method provided by the present invention.

[0186] Examples 17-18

[0187] The cracking catalysts Cat1 and Cat2 were aged at 800℃ for 17 hours under a 100% steam atmosphere. The aged catalysts were then loaded into a fixed-bed microreactor to evaluate their catalytic cracking capacity for light hydrocarbons. The evaluation conditions were: reaction temperature 650℃, regeneration temperature 620℃, and catalyst-to-oil ratio 3.2.

[0188] The properties of the feedstock oil are shown in Table 14.

[0189] The results of the catalytic cracking reaction are shown in Table 15.

[0190] Table 14

[0191] project Light hydrocarbons <![CDATA[Density (20 °C) / (kg·m -3 )]]> 670.7 Elemental mass composition / % C 83.81 H 16.19 <![CDATA[S / mg.L -1 ]]> 2.6 <![CDATA[N / mg.L -1 ]]> <0.3 Distillation range / ℃ Initial boiling point 33.7 10％ 56.3 30％ 69.1 50％ 86.6 70％ 107.2 90％ 130.5 95％ 137.5 Final boiling point 155.7 Hydrocarbon mass composition / % n-Alkanes 72.69 Isoalkanes 25.48 Olefins 0.13 Cycloalkanes 1.56 Aromatics 0.17 total 100.03

[0192] Comparative examples 27, 28, and 29

[0193] Same as Example 17, except that Cat1 is replaced by comparative cracking catalysts DCat1, DCat2, and DCat3 respectively.

[0194] The reaction results are shown in Table 15.

[0195] Table 15

[0196]

[0197]

[0198] Examples 19-20

[0199] The pyrolysis catalysts Cat3-Cat4 were aged at 800℃ for 17 hours under a 100% steam atmosphere. The aged catalysts were then loaded into a fixed-bed microreactor to evaluate their catalytic cracking capacity for light hydrocarbons. The evaluation conditions were: reaction temperature 650℃, regeneration temperature 620℃, and catalyst-to-oil ratio 3.2.

[0200] The reaction results are shown in Table 16.

[0201] Comparative Examples 30, 31, and 32

[0202] Same as Example 19, except that Cat3 is replaced by comparative cracking catalysts DCat4, DCat5, and DCat6 respectively.

[0203] The reaction results are shown in Table 16.

[0204] Table 16

[0205]

[0206] Examples 21-22

[0207] The cracking catalysts Cat5-Cat6 were aged at 800℃ for 17 hours under a 100% steam atmosphere. The aged cracking catalysts were then loaded into a fixed-bed microreactor to evaluate their catalytic cracking ability for light hydrocarbons. The evaluation conditions were: reaction temperature 650℃, regeneration temperature 620℃, and catalyst-to-oil ratio 3.2.

[0208] The reaction results are shown in Table 17.

[0209] Comparative Examples 33, 34, and 35

[0210] Same as Example 21, except that Cat5 is replaced by comparative cracking catalysts DCat7, DCat8, and DCat9 respectively.

[0211] The reaction results are shown in Table 17.

[0212] Table 17

[0213]

[0214] Examples 23-24

[0215] The pyrolysis catalysts Cat7-Cat8 were aged at 800℃ for 17 hours under a 100% steam atmosphere. The aged catalysts were then loaded into a fixed-bed microreactor to evaluate their catalytic cracking capacity for light hydrocarbons. The evaluation conditions were: reaction temperature 650℃, regeneration temperature 620℃, and catalyst-to-oil ratio 3.2.

[0216] The reaction results are shown in Table 18.

[0217] Comparative Examples 33, 34, 35, and 36

[0218] Same as Example 23, except that comparative catalysts DCat10, DCat11, DCat12, and DCat13 are used instead of Cat7.

[0219] The reaction results are shown in Table 18.

[0220] Table 18

[0221]

[0222] As shown in Tables 16, 17, and 18, the cracking catalysts prepared by modifying ZSM-5 molecular sieves with phosphorus compounds having a +1 valence state by low-temperature calcination all exhibit increased hydrocarbon conversion rates and higher ethylene and propylene yields in the catalytic cracking reaction compared to the cracking catalysts prepared by modifying ZSM-5 molecular sieves with phosphorus compounds having a +5 valence state and phosphorus compounds having a +1 valence state by high-temperature calcination.

Claims

1. A catalytic cracking method, comprising reacting hydrocarbon oil with a cracking catalyst under catalytic cracking reaction conditions, wherein the cracking catalyst, by dry weight, contains 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder, and 2-60% clay, characterized in that... The phosphorus-modified ZSM-5 molecular sieve, 31 In the P MAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm; the phosphorus-modified ZSM-5 molecular sieve is obtained by modifying phosphorus-containing compounds with phosphorus in the +1 oxidation state and calcining in air at 300 to 400 °C.

2. The method according to claim 1, characterized in that, The cracking catalyst may be used alone, or the cracking catalyst may be used in a mixture with other cracking catalysts, wherein the cracking catalyst accounts for no more than 30% by weight of the total mixture.

3. The method according to claim 2, characterized in that, In the mixture, the cracking catalyst accounts for 1-25% of the total weight of the mixture.

4. The method according to claim 2, characterized in that, In the mixture, the cracking catalyst accounts for 3-15% of the total weight of the mixture.

5. The method according to claim 1, characterized in that, The catalytic cracking reaction conditions include a reaction temperature of 500-800℃.

6. The method according to claim 1, characterized in that, The hydrocarbon oil is selected from one or more of the following: crude oil, naphtha, gasoline, 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.

7. The method according to claim 1, characterized in that, The Y-type molecular sieve is selected from at least one of PSRY molecular sieve, PSRY-S molecular sieve, rare earth-containing PSRY molecular sieve, rare earth-containing PSRY-S molecular sieve, USY molecular sieve, rare earth-containing USY molecular sieve, REY molecular sieve, REHY molecular sieve, and HY molecular sieve.

8. The method according to claim 1, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 31 In the pMAS-NMR spectrum, the ratio of the area of ​​the resonance signal peak with a chemical shift of -30±3ppm to the area of ​​the resonance signal peak with a chemical shift of -40±3ppm is >1.

9. The method according to claim 1, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 31 In the pMAS-NMR spectrum, the ratio of the resonance signal peak area with a chemical shift of -30±3ppm to that with a chemical shift of -40±3ppm is 1.05 to 1.

4.

10. The method according to claim 1, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 31 In the pMAS-NMR spectrum, the ratio of the peak area of ​​the resonance signal with a chemical shift of -30±3ppm to that with a chemical shift of -40±3ppm is 1.1 to 1.

3.

11. The method according to claim 1, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 27 In the Al MAS-NMR spectrum, resonance signal peaks with chemical shifts of 39±3 ppm and -12±3 ppm appear simultaneously.

12. The method according to claim 1, characterized in that, The phosphorus-modified ZSM-5 molecular sieve, after being washed with hot water at 70°C for 2 hours, has a phosphorus content retention rate of more than 50%. The phosphorus content retention rate is defined as the ratio of P2O5 before washing to P2O5 after washing, calculated as a percentage by mass.

13. The method according to claim 12, characterized in that, After being washed with hot water at 70°C for 2 hours, the phosphorus content retention rate of the phosphorus-modified ZSM-5 molecular sieve was 51-75%.

14. A pyrolysis catalyst, on a dry basis, comprising 2-20% Y-type molecular sieve, 3-80% phosphorus-modified ZSM-5 molecular sieve, 1-70% inorganic binder, and 2-60% clay, characterized in that, The phosphorus-modified ZSM-5 molecular sieve, 31 In the PMAS-NMR spectrum, the chemical shift range of the resonance signal peak is 5 to -20 ppm; the phosphorus-modified ZSM-5 molecular sieve is obtained by modifying phosphorus-containing compounds with phosphorus having a +1 oxidation state and then subjecting the modification to a step including air calcination at 300 to 400°C.

15. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 31 In the PMAS-NMR spectrum, the ratio of the resonance signal peak area with a chemical shift of -30±3ppm to the resonance signal peak area with a chemical shift of -40±3ppm is >1.

16. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 31 In the pMAS-NMR spectrum, the ratio of the resonance signal peak area with a chemical shift of -30±3ppm to that with a chemical shift of -40±3ppm is 1.05 to 1.

4.

17. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 31 In the pMAS-NMR spectrum, the ratio of the resonance signal peak area with a chemical shift of -30±3ppm to that with a chemical shift of -40±3ppm is 1.1 to 1.

3.

18. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve was subjected to hydrothermal aging at 800℃ and 100% steam for 17 hours. 27 In the Al MAS-NMR spectrum, resonance signal peaks with chemical shifts of 39±3ppm and -12±3ppm appear simultaneously.

19. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve, after being washed with hot water at 70°C for 2 hours, has a phosphorus content retention rate of more than 50%. The phosphorus content retention rate is defined as the ratio of P2O5 before washing to P2O5 after washing, calculated as a percentage by mass.

20. The cracking catalyst according to claim 19, characterized in that, After being washed with hot water at 70°C for 2 hours, the phosphorus content retention rate of the phosphorus-modified ZSM-5 molecular sieve was 51-75%.

21. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve has a ratio of 0.01 to 5 when both phosphorus and aluminum are measured in molar amounts.

22. The cracking catalyst according to claim 21, characterized in that, The phosphorus-modified ZSM-5 molecular sieve has a ratio of 0.1 to 3 when both phosphorus and aluminum are measured in molar amounts.

23. The cracking catalyst according to claim 14, characterized in that, The phosphorus-modified ZSM-5 molecular sieve is obtained by contacting and impregnating HZSM-5 molecular sieve with an aqueous solution of a phosphorus-containing compound with a phosphorus oxidation state of +1, followed by drying and air calcination at 300-400°C; or, the phosphorus-modified ZSM-5 molecular sieve is obtained by heating and melting a mixture of HZSM-5 molecular sieve and a solid phosphorus-containing compound with a phosphorus oxidation state of +1, then cooling it to 20-25°C and calcining it in air at 300-400°C.

24. The cracking catalyst according to claim 23, characterized in that, The impregnation is carried out at a water-to-sieve weight ratio of 0.5 to 2 for 0.5 to 10 hours at room temperature; the drying is carried out in an air atmosphere at 100 to 120°C for 2 to 24 hours; the air calcination is carried out at 330 to 370°C for 0.5 to 12 hours.

25. The cracking catalyst according to claim 23, characterized in that, The heating and melting treatment is carried out at a temperature higher than the melting point of the solid phosphorus-containing compound but lower than the temperature at which the solid phosphorus-containing compound decomposes or dehydrates, and the treatment time is 2 to 72 hours.

26. The cracking catalyst according to claim 23, characterized in that, The phosphorus-containing compound with a +1 oxidation state is selected from one or more of hypophosphoric acid, ammonium hypophosphoric acid, and hypophosphite; the aqueous solution of the phosphorus-containing compound with a +1 oxidation state is obtained by adjusting the pH of the aqueous solution of hypophosphoric acid to 5-9 with ammonia.

27. The cracking catalyst according to claim 23, characterized in that, The molar ratio of the HZSM-5 molecular sieve to the phosphorus-containing compound with a +1 valence is (0.1~2.5):1, wherein the HZSM-5 molecular sieve is calculated as aluminum and the phosphorus-containing compound is calculated as phosphorus.

28. The cracking catalyst according to claim 27, characterized in that, The molar ratio of the HZSM-5 molecular sieve to the phosphorus-containing compound with a +1 valence of phosphorus is (0.5~1.5):

1.

29. The cracking catalyst according to claim 14, characterized in that, The inorganic binder includes a phosphorus aluminum inorganic binder, which is 5-40% by weight on a catalyst dry basis.

30. The cracking catalyst according to claim 14 or 29, characterized in that, The inorganic binder also contains at least one selected from boehmite, aluminum sol, silica-alumina sol, and water glass.

31. The cracking catalyst according to claim 14, characterized in that, The clay is selected from at least one of kaolin, sepiolite, attapulgite, raptoite, montmorillonite, and diatomite.

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