Catalytic cracking method and cracking catalyst containing phosphorus modified ZSM-5 molecular sieve

Abstract

The invention relates to a catalytic cracking catalyst which comprises the following components in percentage by dry base weight: 2-20% of a Y-type molecular sieve, 3-80% of a phosphorus modified ZSM-5 molecular sieve, 1-70% of an inorganic binder and 2-60% of clay, and is characterized in that in a 31P MAS-NMR spectrogram, the chemical shift range of a resonance signal peak of the phosphorus modified ZSM-5 molecular sieve is 5-20 ppm, and the chemical shift range of the resonance signal peak of the phosphorus modified ZSM-5 molecular sieve is 5-20 ppm. And after hydrothermal aging for 17h under the conditions of 800 DEG C and 100% water vapor, the resonance signal peak area ratio of-30 + / -3ppm to-40 + / -3ppm of chemical shifts is greater than 1.

Description

Technical Field

[0001] The present invention relates to a cracking method and a cracking catalyst, and more particularly to a catalytic cracking method and a cracking catalyst containing Y-type molecular sieve and phosphorus-modified ZSM-5 molecular sieve. Background Art

[0002] The cracking reaction of hydrocarbons at high temperature is to convert long-chain hydrocarbons into high-value-added light olefins such as ethylene and propylene. ZSM-5 molecular sieve is a mesoporous molecular sieve with a high-silica three-dimensional straight channel structure of MFI type developed by Mobil Oil Company of the United States (USP3702886). Its unique pore structure endows it with good shape-selective catalysis and isomerization performance. It also has characteristics such as high thermal and hydrothermal stability, high specific surface area, wide range of silicon-aluminum ratio variation, unique surface acidity, and low carbon deposition amount. ZSM-5 molecular sieve is widely used as a catalyst and catalyst carrier, and has been successfully applied in production processes such as alkylation, isomerization, disproportionation, catalytic cracking, methanol-to-gasoline, and methanol-to-olefins.

[0003] Since 1983, ZSM-5 molecular sieve has been applied to the catalytic cracking process as a catalytic cracking octane number promoter, aiming to improve the octane number of catalytic cracking gasoline and the selectivity of light olefins. US3758403 first reported using ZSM-5 as an active component for increasing propylene production, that is, preparing an FCC catalyst by using ZSM-5 and REY together as active components. US5997728 discloses using ZSM-5 molecular sieve as an additive for increasing propylene production without any modification of the molecular sieve. The propylene yields of the above two technologies are not high. Although HZSM-5 molecular sieve has good shape-selective performance and isomerization performance, its disadvantage is poor hydrothermal stability, and it is easily deactivated under harsh high-temperature hydrothermal conditions, resulting in a decrease in catalytic performance.

[0004] In the 1980s, Mobil Company found that phosphorus can improve the hydrothermal stability of ZSM-5 molecular sieve. At the same time, after modifying ZSM-5 molecular sieve with phosphorus, the primary cracking products (such as gasoline olefins) can be selectively converted into C3 and C4 olefins, increasing the light olefin yield.

[0005] CN 1211469A discloses a pentacyclic molecular sieve composition for producing more propylene and ethylene, which is composed of 85-95% by weight of pentacyclic molecular sieve, 2-10% by weight of phosphorus in terms of oxide, 0.3-5% by weight of alkaline earth metal in terms of oxide, and 0.3-5% by weight of transition metal element in terms of oxide. When this composition is used in catalytic thermal cracking reaction, a higher ethylene yield can be obtained.

[0006] A ZSM-5 molecular sieve modified with phosphorus disclosed in US5171921, having a silica-alumina ratio of 20-60, after being impregnated with a phosphorus-containing compound and treated with steam at 500-700 °C, has higher activity when used in the reaction of converting C3-C20 hydrocarbons into C2-C5 olefins compared to the untreated HZSM-5.

[0007] A preparation method of a phosphorus-modified ZSM-5 molecular sieve disclosed in CN102166533A is to add the molecular sieve into an aqueous solution containing phosphorus, react for a period of time under certain pH value, temperature and pressure, then filter, dry and calcine to obtain the phosphorus-modified molecular sieve; thereafter, add the phosphorus-modified molecular sieve into an aqueous solution containing rare earth ions, react for a period of time under certain temperature and pressure, then filter, wash, dry and calcine to obtain the composite-modified molecular sieve. Using this composite-modified molecular sieve to prepare a model catalyst has higher hydrothermal stability and microactivity performance than the model catalysts containing unmodified and other modified molecular sieves.

[0008] A preparation method of a phosphorus-modified ZSM-5 molecular sieve disclosed in CN106994364A is to first mix a ZSM-5 molecular sieve with a high alkali metal ion content with a phosphorus-containing compound selected from one or more of phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and ammonium phosphate to obtain a mixture with a phosphorus loading of at least 0.1 wt% calculated as P2O5. The mixture is dried, calcined, then subjected to an ammonium exchange step and a water washing step to reduce the alkali metal ion content to below 0.10 wt%, and then undergoes drying and hydrothermal aging at 400-1000 °C and 100% steam conditions. The phosphorus-containing ZSM-5 molecular sieve obtained by this preparation method has a high total acid amount, excellent cracking conversion rate and selectivity for propylene, and at the same time has a high liquefied gas yield.

[0009] Although modifying the ZSM-5 molecular sieve with organic / inorganic phosphorus-containing compounds can inhibit framework dealumination and thus improve hydrothermal stability, the introduction of phosphorus species also has the effect of regulating the nature of the acid centers of the ZSM-5 molecular sieve, improving the cracking conversion rate of long-chain alkanes and the selectivity for light olefins. However, phosphoric acid or ammonium phosphate salts will dehydrate and self-polymerize to form macromolecular phosphorus species such as polyphosphoric acid, which are easily enriched 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 and unable to achieve the ideal effect of improving hydrothermal stability after phosphorus modification. Summary of the Invention

[0010] Based on a large number of experiments, the inventors found that the phosphorus-modified ZSM-5 zeolite prepared from solid phosphorus-containing compounds with a valence of +1 such as hypophosphorous acid and hypophosphite has physicochemical characteristics different from those of the zeolite prepared by the conventional impregnation method using a +5-valent phosphorus source aqueous solution, and can improve the phosphorus-aluminum stabilization efficiency. The hydrothermal stability, cracking activity, and light olefin selectivity of the ZSM-5 zeolite modified in this way are all improved.

[0011] One of the objectives of the present invention is to provide a catalytic cracking method. One of the active components in the catalyst used in this method is a phosphorus-modified ZSM-5 zeolite with physicochemical characteristics different from those of the conventional phosphorus-containing ZSM-5 zeolite and an improved phosphorus-aluminum stabilization efficiency of the zeolite. This method has a high cracking conversion rate and light olefin yield, and a high liquefied gas yield in the catalytic cracking reaction of hydrocarbon oil; the second objective is to provide the cracking catalyst used in this cracking method.

[0012] To achieve the above objective one, a catalytic cracking method provided in the first aspect of the present invention is to carry out a contact reaction between hydrocarbon oil and a cracking catalyst under catalytic cracking reaction conditions. Based on the dry basis weight, the cracking catalyst contains 2-20% of Y-type zeolite, 3-80% of phosphorus-modified ZSM-5 zeolite, 1-70% of inorganic binder, and 2-60% of clay. It is characterized in that the phosphorus-modified ZSM-5 zeolite, its 31 In the PMAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5 to -20 ppm.

[0013] To achieve the above objective two, the second aspect of the present invention provides a cracking catalyst. Based on the dry basis weight, it contains 2-20% of Y-type zeolite, 3-80% of phosphorus-modified ZSM-5 zeolite, 1-70% of inorganic binder, and 2-60% of clay. It is characterized in that the phosphorus-modified ZSM-5 zeolite, its 31 In the PMAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5 to -20 ppm.

[0014] The catalytic cracking method provided by the present invention uses a catalyst containing a phosphorus-modified ZSM-5 zeolite with special physicochemical parameters. This phosphorus-modified ZSM-5 zeolite is obtained by modification with a +1-valent phosphorus source; its 31 In the P MAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5 to -20 ppm. Description of the Drawings

[0015] Figure 1 For the 31 P MAS-NMR spectrum of the phosphorus-modified ZSM-5 zeolite sample.

[0016] Figure 2 PMAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h 31 PMAS-NMR spectra

[0017] Figure 3 Al MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 27 Al MAS-NMR spectra

[0018] Figure 4 P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 31 P MAS-NMR spectra

[0019] Figure 5 PMAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h 31 PMAS-NMR spectra

[0020] Figure 6 Al MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 27 Al MAS-NMR spectra

[0021] Figure 7 P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 31 P MAS-NMR spectra

[0022] Figure 8 PMAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h 31 PMAS-NMR spectra

[0023] Figure 9 Al MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 27 Al MAS-NMR spectra

[0024] Figure 10 P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 31 P MAS-NMR spectra

[0025] Figure 11 PMAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h 31 PMAS-NMR spectra

[0026] Figure 12 Al MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample 27 Al MAS-NMR spectra Detailed implementation methods

[0027] The catalytic cracking method provided by the present invention is to make hydrocarbon oil contact and react with a cracking catalyst under catalytic cracking reaction conditions. Based on dry basis weight, the cracking catalyst contains 2-20% of Y-type molecular sieve, 3-80% of phosphorus-modified ZSM-5 molecular sieve, 1-70% of inorganic binder and 2-60% of clay. It is characterized in that the phosphorus-modified ZSM-5 molecular sieve, its 31 In the P MAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5~-20 ppm. The phosphorus-modified ZSM-5 molecular sieve is obtained by modifying with a phosphorus-containing compound with a phosphorus valence state of +1.

[0028] In the method of the present invention, the cracking feedstock can be various hydrocarbon oils. The hydrocarbon oil can be selected from various petroleum fractions, such as crude oil, naphtha, catalytic gasoline, atmospheric residue, vacuum residue, atmospheric gas oil, vacuum gas oil, straight-run gas oil, propane light / heavy deoiled oil, coker gas oil and coal liquefaction products, one or more of them. The hydrocarbon oil can contain heavy metal impurities such as nickel and vanadium and 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 metal 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 conventional in the art, preferably including: reaction temperature 500~800 °C, for example 550~680 °C.

[0030] In the method of the present invention, the cracking catalyst can be used alone, that is, it can be added alone into the catalytic cracking reactor. For example, under catalytic cracking conditions, the hydrocarbon oil is made to contact and react with the catalytic cracking catalyst of the present invention. Or, the cracking catalyst forms a mixture with other conventional cracking catalysts. In the mixture, the cracking catalyst of the present invention accounts for no more than 30 wt% of the total amount of the mixture, preferably 1-25 wt%, more preferably 3-15 wt%. The other conventional cracking catalysts are well-known to those skilled in the art, mainly cracking catalysts with Y-type molecular sieve as the main active component, which will not be elaborated here.

[0031] The cracking catalyst in the method of the present invention contains 2-20% of Y-type molecular sieve. The Y-type molecular sieve can 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 cracking catalyst in the method of the present invention contains 3-80% of phosphorus-modified ZSM-5 molecular sieve. The phosphorus-modified ZSM-5 molecular sieve has physicochemical characterization parameters different from those of the prior art. 31In the P MAS-NMR spectrum, due to the diversity of phosphorus species, the chemical shifts of the resonance signal peaks it generates have a certain range, representing the degree of condensation of the overall phosphorus species. The resonance signal peaks in the low-field range of 0 ppm, -6 ppm, -15 ppm, etc. represent phosphorus species with a relatively low degree of condensation such as monomeric phosphoric acid and pyrophosphoric acid, while the resonance signal peaks in the range of -20 to -40 ppm represent polyphosphoric acid species with a relatively high degree of condensation. The inventors of the present invention unexpectedly found that during the preparation of phosphorus-modified ZSM-5 molecular sieves, a roasting method different from the conventional 550 °C roasting method in the prior art was adopted, and it was replaced by low-temperature roasting at 300 to 400 °C in an air atmosphere. After that, the chemical shift range of the resonance signal peaks was 5 to -20 ppm, indicating that the degree of condensation of its phosphorus species was relatively low; while for the phosphorus-modified molecular sieve obtained by the conventional 550 °C roasting method in the prior art, the degree of condensation of the phosphorus species was relatively high, and the chemical shift range of the resonance signal peaks was 5 to -50 ppm.

[0033] Furthermore, after the phosphorus-modified ZSM-5 molecular sieve in the present invention is hydrothermally aged for 17 h under the conditions of 800 °C and 100% water vapor, 31 In the P MAS-NMR spectrum, the ratio of the resonance signal peak area with a chemical shift of -30 ± 3 ppm to the resonance signal peak area with a chemical shift of -40 ± 3 ppm > 1. Preferably, the area ratio is 1.05 to 1.4, and more preferably, the area ratio is 1.1 to 1.3. Among them, the resonance signal with a chemical shift of -30 ± 3 ppm represents the tetracoordinated phosphorus species formed after stabilizing the framework aluminum species, and the resonance signal with a chemical shift of -40 ± 3 ppm represents the condensed pentacoordinated phosphorus species. The larger the ratio of the resonance signal peak areas of -30 ± 3 ppm to -40 ± 3 ppm, the more phosphorus species in the phosphorus-modified molecular sieve that can stabilize the framework aluminum. In the prior art, the ratio of the resonance signal peak areas of -30 ± 3 ppm to -40 ± 3 ppm of the ZSM-5 molecular sieve modified with phosphorus-containing precursors with a phosphorus valence of +5 such as diammonium hydrogen phosphate or phosphoric acid < 1.

[0034] Furthermore, after the phosphorus-modified ZSM-5 molecular sieve in the present invention is hydrothermally aged for 17 h under the conditions of 800 °C and 100% water vapor, 27 In the Al MAS-NMR spectrum, resonance signal peaks with chemical shifts of 39 ± 3 ppm and -12 ± 3 ppm appear simultaneously. Among them, the resonance signal with a chemical shift of 39 ± 3 ppm represents the framework aluminum species stabilized after coordinating with phosphorus species, that is, distorted tetracoordinated framework aluminum; the resonance signal with a chemical shift of -12 ± 3 ppm represents the extra-framework aluminum species combined with phosphorus species.

[0035] In the present invention, the phosphorus-modified ZSM-5 molecular sieve has a higher phosphorus retention rate after water washing. For example, after water washing with hot water at 70 °C for 2 h, the phosphorus content retention rate is higher than 50%, about 51-75%; in the prior art, the phosphorus content retention rate is less than 50%. The definition of the phosphorus content retention rate is P2O5 before water washing / P2O5 after water washing, calculated as a mass percentage.

[0036] In the present invention, for the phosphorus-modified ZSM-5 molecular sieve, when both phosphorus and aluminum are measured in moles, the ratio of the two is 0.01-5, and the preferred ratio is 0.1-3.

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

[0038] In one more specific embodiment, it can be that after the HZSM-5 molecular sieve is contacted and impregnated with an aqueous solution of a phosphorus-containing compound with a phosphorus valence state of +1, it is dried and then calcined in air at 300-400 °C to obtain the phosphorus-modified ZSM-5 molecular sieve. In the impregnation, the weight ratio of water to sieve is 0.5-2, and it is carried out for 0.5-10 hours; for the drying, the atmosphere is air, carried out at 100-120 °C for 2-24 hours; for the calcination, the atmosphere is air, carried out at 300-400 °C, preferably 330-370 °C, more preferably 350 °C for 0.5-12 hours.

[0039] In one more specific embodiment, it can be that after the mixture obtained by mixing and grinding the HZSM-5 molecular sieve with a solid phosphorus-containing compound with a phosphorus valence state of +1 is subjected to heat melting treatment, it is cooled to 20-25 °C and then calcined at 300-400 °C. In the heat melting treatment, the temperature is higher than the melting point of the solid phosphorus-containing compound and lower than the temperature at which the solid phosphorus-containing compound decomposes or dehydrates (for example, the melting point of hypophosphorous acid is 26.5 °C and the decomposition temperature is 130 °C), and the treatment time is 2-72 hours.

[0040] The HZSM-5 zeolite is treated with a phosphorus-containing compound in which the valence state of phosphorus is +1. By selecting a +1-valent phosphorus source with a relatively small molecule, the migration process of phosphorus species into the pores of the ZSM-5 zeolite is accelerated, and the activation efficiency of phosphorus-aluminum species is improved. The phosphorus-containing compound in which the valence state of phosphorus is +1 is one or more of hypophosphorous acid, ammonium hypophosphite, and hypophosphite; alternatively, the aqueous solution of the phosphorus-containing compound in which the valence state of phosphorus is +1 is obtained by adjusting the pH value of the aqueous solution of hypophosphorous acid to 5-9 with ammonia water. As a phosphorus-containing precursor, after air calcination at 300-400 °C, especially 350 °C, phosphorus is converted from the +1 valence state to a higher oxidation state and has the condition to stabilize framework aluminum during the aging process.

[0041] Regarding the phosphorus-modified ZSM-5 zeolite involved in the present application, the content of the Chinese invention application with the application number 202310788556.0 and the filing date of June 30, 2023 is incorporated herein by reference.

[0042] In the cracking catalyst described in the method of the present invention, preferably, the Y-type zeolite and the phosphorus-modified ZSM-5 zeolite account for 6-85% of the dry basis weight of the cracking catalyst. Further, the Y-type zeolite based on the dry basis weight accounts for 3-15% of the dry basis of the cracking catalyst, and the phosphorus-modified zeolite based on the dry basis weight accounts for 5-75% of the cracking catalyst. More preferably, the weight ratio of the Y-type zeolite to the phosphorus-modified ZSM-5 zeolite is 1:(0.25-40).

[0043] In the cracking catalyst used in the method of the present invention, the inorganic binder includes a phosphoaluminum inorganic binder, and based on the dry basis of the catalyst, the phosphoaluminum inorganic binder is 5-40% by weight. Based on the dry basis weight of the phosphoaluminum inorganic binder, the phosphoaluminum inorganic binder includes 15-40% by weight of an aluminum component based on Al2O3 and 45-80% by weight of a phosphorus component based on P2O5, and its P / Al weight ratio is 1.0-6.0, the pH value is 1-3.5, and the solid content is 15-60% by weight; for example, it includes 15-40% by weight of an aluminum component based on Al2O3 and 45-80% by weight of a phosphorus component based on P2O5; preferably, it contains 15-35% by weight of an aluminum component based on Al2O3 and 50-75% by weight of a phosphorus component based on P2O5, and its P / Al weight ratio is preferably 1.2-6.0, more preferably 2.0-5.0, and the pH value is preferably 1.5-3.0. Preferably, based on the dry basis weight of the phosphoaluminum inorganic binder, the phosphoaluminum inorganic binder includes 20-40% by weight of an aluminum component based on Al2O3 and 60-80% by weight of a phosphorus component based on P2O5. The phosphoaluminum inorganic binder can be prepared by the following steps: slurrying and dispersing an alumina source, clay (such as rectorite, kaolin) and water into a slurry with a solid content of 5-50% by weight; wherein the alumina source is aluminum hydroxide and / or alumina that can be acid peptized (such as pseudoboehmite, 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 in a stirred state according to a weight ratio of P / Al = 1-6, and reacting the resulting mixed slurry at 50-99 °C for 15-90 minutes; wherein P in the P / Al is the weight of phosphorus in the phosphoric acid in elemental form, and Al is the weight of aluminum in elemental form in the alumina source.

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

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

[0046] For the cracking catalyst used in the method of the present invention, in a specific preparation embodiment of its preparation process, an inorganic binder (such as pseudo-boehmite, aluminum sol, silica sol, silica-alumina gel or a mixture of two or more thereof) can be mixed with clay (such as kaolin) and water (such as deoxygenated ion water and / or deionized water) to prepare a slurry with a solid content of 10-50% by weight, 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. After maintaining this pH value and standing and aging at 20-80°C for 0-2 hours (such as 0.3-2 hours), aluminum sol and / or silica sol are added, stirred for 0.5-1.5 hours to form a colloid, and then molecular sieves are added. The molecular sieves include the phosphorus-modified ZSM-5 molecular sieve and Y-type molecular sieve to form a catalyst slurry. The solid content of the catalyst slurry is, for example, 20-45% by weight. After continuous stirring, it is spray-dried to make a microsphere catalyst. Then the microsphere catalyst is calcined (such as calcined at 350-650°C or 400-600°C, preferably 450-550°C for 0.5-6 hours or 0.5-2 hours), and then washed with ammonium sulfate (wherein the washing temperature can be 40-70°C, ammonium sulfate: microsphere catalyst: water = 0.2-0.8:1:5-15 by weight ratio) until the sodium oxide content is less than 0.25% by weight, washed with water and filtered, and then dried.

[0047] In another specific preparation embodiment of the preparation process of the cracking catalyst used in the method of the present invention, Y-type molecular sieve, phosphorus-modified ZSM-5 molecular sieve, phosphoaluminum inorganic binder and other inorganic binders can be mixed, clay is added, and then slurried and spray-dried.

[0048] The present invention further provides a cracking catalyst for the above cracking method. Based on the dry basis weight, it contains 2-20% of Y-type molecular sieve, 3-80% of phosphorus-modified ZSM-5 molecular sieve, 1-70% of inorganic binder and 2-60% of clay, wherein the phosphorus-modified ZSM-5 molecular sieve 31 In the P MAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5 to -20 ppm. This phosphorus-modified ZSM-5 molecular sieve is modified with a phosphorus-containing compound with a phosphorus valence state of +1 and obtained through a step including air calcination at 300-400°C.

[0049] The following details the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention.

[0050] The X-ray diffraction (XRD) pattern was determined on a Rigaku TTR-3 powder X-ray diffractometer in Japan. Instrument parameters: copper target (tube voltage 40 kV, tube current 250 mA), scintillation counter, step width 0.02°, scanning rate 0.4 (°) / min. The ZSM-5 molecular sieve synthesized by the method of Example 1 in CN1056818C was used as a standard sample, and its crystallinity was set at 100%. The relative crystallinity is expressed as a percentage of the ratio of the sum of the peak areas of five characteristic diffraction peaks with 2θ between 22.5 and 25.0° in the X-ray diffraction patterns of the obtained product and the standard sample.

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

[0052] 27 The Al MAS-NMR spectrum analysis was carried out on a Bruker AVANCE III 600WB spectrometer. Instrument parameters: rotor diameter 4 mm, resonance frequency spectrum 156.4 MHz, pulse width 0.4 μs (corresponding to a 15° flip angle), magic angle spinning speed 12 kHz, delay time 1 s. 27 For the characteristics of the Al MAS-NMR spectrum, the characteristic peak at 39 ± 3 ppm is attributed to phosphorus-stabilized framework aluminum (distorted tetrahedral coordinated framework aluminum), and the full width at half maximum of this characteristic peak was calculated by deconvolution fitting.

[0053] X-ray photoelectron spectroscopy (XPS) was used for the analysis of phosphorus species on the surface of the molecular sieve to investigate the valence state changes of the phosphorus compounds loaded on the phosphorus-modified molecular sieve after drying and calcination. An ESCALAB 250 X-ray photoelectron spectrometer from Thermo Fisher-VG was used. Instrument parameters: the excitation source is monochromatized AlKα X-ray with a power of 150 W, and the charge shift was corrected using the C1s peak (284.8 eV) from contaminated carbon.

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

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

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

[0057] The aluminum sol is an industrial product produced by Qilu Branch of Sinopec Catalyst Co., Ltd., with an Al2O3 content of 21.5 wt%.

[0058] The silica sol is an industrial product produced by Qilu Branch of Sinopec Catalyst Co., Ltd., with an SiO2 content of 28.9 wt% and an Na2O content of 8.9%.

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

[0060] The SB aluminum hydroxide powder is produced by German Condex Co., Ltd., with an Al2O3 content of 75 wt%.

[0061] The HRY molecular sieve is an industrial product produced by Changling Branch of Sinopec Catalyst Co., Ltd., with a rare earth content of 10 wt%.

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

[0063] The instruments and reagents used in the examples of the present invention are, unless otherwise specified, the 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 the present invention.

[0065] Example 1

[0066] Take 6.9 g of hypophosphorous acid and dissolve it in 145 g of deionized water at 25°C, stir for 0.5 h to obtain an aqueous solution containing phosphorus, add 100 g of HZSM - 5 molecular sieve (nSiO2 / nAl2O3 = 30), modify it by the impregnation method, impregnate at 25°C for 0.5 h, then transfer it to an oven for drying at 120°C for 12 h, and perform calcination treatment in a muffle furnace under an air atmosphere at 350°C for 2 h to obtain the phosphorus - modified ZSM - 5 molecular sieve sample, denoted as TCB - 1.

[0067] Example 2

[0068] 6.9 g of solid hypophosphorous acid was added to 100 g of HZSM-5 zeolite (nSiO2 / nAl2O3 = 30), and the mixture was ground for 0.5 h and then transferred to a Teflon-lined stainless steel autoclave for a melting process at 40 °C for 10 h. After completion, the sample was taken out after naturally cooling to room temperature; the above sample was calcined at 350 °C for 2 h to obtain a phosphorus-containing ZSM-5 zeolite sample, denoted as TRCB-1.

[0069] Comparative Example 1

[0070] 13.9 g of diammonium hydrogen phosphate was dissolved in 145 g of deionized water at 25 °C, and the mixture was stirred for 0.5 h to obtain a phosphorus-containing aqueous solution. 100 g of HZSM-5 zeolite (nSiO2 / nAl2O3 = 30) was added, and it was modified by the impregnation method. After impregnation at 25 °C for 0.5 h, it was transferred to an oven for drying at 120 °C for 12 h, and then calcined at 550 °C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-containing ZSM-5 zeolite comparative sample, denoted as DPB-1.

[0071] Comparative Example 2

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

[0073] Comparative Example 3

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

[0075] The P MAS-NMR spectra of the phosphorus-modified ZSM-5 zeolite samples TCB-1, TRCB-1, and the comparative samples DPB-1, DPB-2, JCB-1 31 are shown in Figure 1 . Figure 1Among them, the characteristic peaks at chemical shifts of 0 ppm, -6 ppm, and -15 ppm belong to oligophosphorus species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm belong to high-polymeric phosphorus species.

[0076] For the phosphorus-modified ZSM-5 molecular sieve samples TCB-1, TRCB-1, and the comparative samples DPB-1, DPB-2, and JCB-1, after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h 31 The P MAS-NMR spectra are shown in Figure 2 . Figure 2 Among them, the resonance signal with a chemical shift of -30 ± 3 ppm represents the tetracoordinated phosphorus species formed after stabilizing the framework aluminum species, and the resonance signal of -40 ± 3 ppm represents the condensed pentacoordinated phosphorus species. The ratio of the signal peak area at -30 ± 3 ppm to the signal peak area at -40 ± 3 ppm is shown in Table 1.

[0077] For the phosphorus-modified ZSM-5 molecular sieve samples TCB-1, TRCB-1, and the comparative samples DPB-1, DPB-2, and JCB-1 27 The Al MAS-NMR spectra are shown in Figure 3 .

[0078] The relative crystallinity and crystallinity retention of the phosphorus-modified ZSM-5 molecular sieve samples TCB-1, TRCB-1, and the comparative samples DPB-1, DPB-2, and JCB-1 before and after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h are shown in Table 2.

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

[0080] Table 1

[0081] Sample Signal peak area ratio of -30±3 ppm / -40±3 ppm 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 Retention rate of phosphorus content / % TCB-1 62 TRCB-1 61 DPB-1 45 DPB-2 48 JCB-1 49

[0086] Example 3

[0087] Take 3.45 g of hypophosphorous acid and dissolve it in 145 g of deionized water at 25 °C. Stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 zeolite (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating at 25 °C for 0.5 h, transfer it to an oven and dry at 120 °C for 12 h. Then, perform a calcination treatment at 350 °C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-containing ZSM-5 zeolite sample, denoted as TCB-2.

[0088] Example 4

[0089] Take 3.45 g of solid hypophosphorous acid and add it to 100 g of HZSM-5 zeolite (nSiO2 / nAl2O3 = 30). Grind and mix them for 0.5 h, then transfer to a stainless steel autoclave with a Teflon liner and carry out a melting process at a heating temperature of 40 °C for 10 h. After completion, wait for the sample to naturally cool to room temperature and then take it out. The above sample is calcined at 350 °C for 2 h to obtain a phosphorus-modified ZSM-5 zeolite sample, denoted as TRCB-2.

[0090] Comparative Example 4

[0091] Take 6.95 g of diammonium hydrogen phosphate and dissolve it in 145 g of deionized water at 25 °C. Stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 zeolite (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating at 25 °C for 0.5 h, transfer it to an oven and dry at 120 °C for 12 h. Then, perform a calcination treatment at 550 °C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 zeolite comparative sample, denoted as DPB-3.

[0092] Comparative Example 5

[0093] Take 6.05 g of phosphoric acid solution (mass fraction 85 wt%) and dissolve it in 145 g of deionized water at 25 °C. Stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 zeolite (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating at 25 °C for 0.5 h, transfer it to an oven and dry at 120 °C for 12 h. Then, perform a calcination treatment at 550 °C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 zeolite comparative sample, denoted as DPB-4.

[0094] Comparative Example 6

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

[0096] The P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve samples TCB-2, TRCB-2, and the comparative samples DPB-3, DPB-4, JCB-2 31 are shown in Figure 4 . Figure 4 Among them, the characteristic peaks at chemical shifts of 0 ppm, -6 ppm, and -15 ppm are attributed to oligophosphorus species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm are attributed to high-polymeric phosphorus species.

[0097] After the phosphorus-modified ZSM-5 molecular sieve samples TCB-2, TRCB-2, and the comparative samples DPB-3, DPB-4, JCB-2 were hydrothermally aged at 800 °C, 100% water vapor for 17 h, 31 their P MAS-NMR spectra are shown in Figure 5 . Figure 5 Among them, the resonance signal at a chemical shift of -30 ± 3 ppm represents the tetracoordinated phosphorus species formed after the stabilization of framework aluminum species, and the resonance signal at -40 ± 3 ppm represents the condensed pentacoordinated phosphorus species. The area ratio of the -30 ± 3 ppm / -40 ± 3 ppm signal peaks is shown in Table 4.

[0098] Figure 6 is 27 the spectrum of Al MAS-NMR.

[0099] The relative crystallinity and crystallization retention of the phosphorus-modified ZSM-5 molecular sieve samples TCB-2, TRCB-2, and the comparative samples DPB-3, DPB-4, JCB-2 before and after hydrothermal aging at 800 °C, 100% water vapor for 17 h are shown in Table 5.

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

[0101] Table 4

[0102] Sample Signal peak area ratio of -30±3 ppm / -40±3 ppm 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 Retention rate of phosphorus content / % TCB-2 70 TRCB-2 71 DPB-3 48 DPB-4 46 JCB-2 47

[0107] Example 5

[0108] Take 10.35 g of hypophosphorous acid and dissolve it in 145 g of deionized water at 25°C. Add ammonia water to adjust the pH value of the solution within the range of 5 - 9, and stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating for 0.5 h at 25°C, transfer it to an oven and dry at 120°C for 12 h. Then, perform a calcination treatment at 350°C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 molecular sieve sample, denoted as TCB-3.

[0109] Example 6

[0110] Take 13.02 g of ammonium hypophosphite and add it to 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30). Grind and mix them for 0.5 h, then transfer them to a stainless steel autoclave with a Teflon liner and carry out a melting process at a heating temperature of 40°C for 10 h. After completion, wait for the sample to naturally cool to room temperature and then take it out. After calcining the above sample at 350°C for 2 h, a phosphorus-modified ZSM-5 molecular sieve sample is obtained, denoted as TRCB-3.

[0111] Comparative Example 7

[0112] Take 20.85 g of diammonium hydrogen phosphate and dissolve it in 145 g of deionized water at 25°C. Stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating for 0.5 h at 25°C, transfer it to an oven and dry at 120°C for 12 h. Then, perform a calcination treatment at 550°C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as DPB-5.

[0113] Comparative Example 8

[0114] Take 18.15 g of phosphoric acid solution (mass fraction 85 wt%) and dissolve it in 145 g of deionized water at 25°C. Stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating for 0.5 h at 25°C, transfer it to an oven and dry at 120°C for 12 h. Then, perform a calcination treatment at 550°C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as DPB-6.

[0115] Comparative Example 9

[0116] Take 10.35 g of hypophosphorous acid and dissolve it in 145 g of deionized water at 25°C. Add ammonia water to adjust the pH value of the solution within the range of 5 - 9, and stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 30), and modify it by the impregnation method. After impregnating for 0.5 h at 25°C, transfer it to an oven and dry at 120°C for 12 h, and then calcine it in a muffle furnace under an air atmosphere at 550°C for 2 h to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as JCB-4.

[0117] The 31 P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve samples TCB-3, TRCB-3, and the comparative samples DPB-5, DPB-6, JCB-4 are shown in Figure 7 . Figure 7 Among them, the characteristic peaks at chemical shifts of 0 ppm, -6 ppm, and -15 ppm belong to oligophosphorus species such as monomeric phosphoric acid and pyrophosphoric acid; the characteristic peaks in the range of -20 to -50 ppm belong to high-polymeric phosphorus species.

[0118] The 31 P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve samples TCB-3, TRCB-3, and the comparative samples DPB-5, DPB-6, JCB-4 after being hydrothermally aged at 800°C, 100% water vapor, and for 17 h are shown in Figure 8 . Figure 8 Among them, the resonance signal at a chemical shift of -30 ± 3 ppm represents the four-coordinate phosphorus species formed after the stable framework aluminum species, and the resonance signal at -40 ± 3 ppm represents the condensed five-coordinate phosphorus species. The area ratio of the -30 ± 3 ppm / -40 ± 3 ppm signal peaks is shown in Table 7.

[0119] Figure 9 is 27 the spectrum of Al MAS-NMR.

[0120] The relative crystallinity and crystallization retention of the phosphorus-modified ZSM-5 molecular sieve samples TCB-3, TRCB-3, and the comparative samples DPB-5, DPB-6, JCB-4 before and after being hydrothermally aged at 800°C, 100% water vapor, and for 17 h are shown in Table 8.

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

[0122] Table 7

[0123] Sample Signal peak area ratio of -30±3 ppm / -40±3 ppm 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 Retention rate of phosphorus content / % TCB-3 58 TRCB-3 55 DPB-5 42 DPB-6 41 JCB-4 45

[0128] Example 7

[0129] Take 1.36 g of ammonium hypophosphite and dissolve it in 145 g of deionized water at 25°C, stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 100), modify it by the impregnation method, after impregnating for 0.5 h at 25°C, transfer it to an oven and dry it at 120°C for 12 h, and perform calcination treatment at 350°C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 molecular sieve sample, denoted as TCB-4.

[0130] Comparative Example 10

[0131] Take 2.16 g of diammonium hydrogen phosphate and dissolve it in 145 g of deionized water at 25°C, stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 100), modify it by the impregnation method, after impregnating for 0.5 h at 25°C, transfer it to an oven and dry it at 120°C for 12 h, and perform calcination treatment at 550°C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as DPB-7.

[0132] Comparative Example 11

[0133] Take 1.36 g of ammonium hypophosphite and dissolve it in 145 g of deionized water at 25°C, stir for 0.5 h to obtain an aqueous solution containing phosphorus. Add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 100), modify it by the impregnation method, after impregnating for 0.5 h at 25°C, transfer it to an oven and dry it at 120°C for 12 h, and perform calcination treatment at 550°C for 2 h in an air atmosphere in a muffle furnace to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as JCB-5.

[0134] Example 8

[0135] Dissolve 0.91 g of ammonium hypophosphite in 145 g of deionized water at 25 °C, stir for 0.5 h to obtain an aqueous solution containing phosphorus, add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 150), modify it by the impregnation method, impregnate for 0.5 h at 25 °C, then transfer it to an oven for drying at 120 °C for 12 h, and calcine it in a muffle furnace under an air atmosphere at 350 °C for 2 h to obtain a phosphorus-modified ZSM-5 molecular sieve sample, denoted as TCB-5.

[0136] Comparative Example 12

[0137] Dissolve 1.45 g of diammonium hydrogen phosphate in 145 g of deionized water at 25 °C, stir for 0.5 h to obtain an aqueous solution containing phosphorus, add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 150), modify it by the impregnation method, impregnate for 0.5 h at 25 °C, then transfer it to an oven for drying at 120 °C for 12 h, and calcine it in a muffle furnace under an air atmosphere at 550 °C for 2 h to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as DPB-8.

[0138] Comparative Example 13

[0139] Dissolve 0.91 g of ammonium hypophosphite in 145 g of deionized water at 25 °C, stir for 0.5 h to obtain an aqueous solution containing phosphorus, add 100 g of HZSM-5 molecular sieve (nSiO2 / nAl2O3 = 150), modify it by the impregnation method, impregnate for 0.5 h at 25 °C, then transfer it to an oven for drying at 120 °C for 12 h, and calcine it in a muffle furnace under an air atmosphere at 550 °C for 2 h to obtain a phosphorus-modified ZSM-5 molecular sieve comparative sample, denoted as JCB-6.

[0140] The P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample TCB-4, the comparative sample DPB-7, the comparative sample JCB-5, the sample TCB-5, the comparative sample DPB-8, and the comparative sample JCB-6 31 are shown in Figure 10 . Figure 10 Among them, the characteristic peaks at chemical shifts of 0 ppm, -6 ppm, and -15 ppm are attributed to monomeric phosphoric acid, pyrophosphoric acid and other oligophosphorus species; the characteristic peaks in the range of -20 to -50 ppm are attributed to high-polymeric phosphorus species.

[0141] The P MAS-NMR spectra of the phosphorus-modified ZSM-5 molecular sieve sample TCB-4, the comparative sample DPB-7, the comparative sample JCB-5, the sample TCB-5, the comparative sample DPB-8, and the comparative sample JCB-6 after being hydrothermally aged at 800 °C, 100% steam, and 17 h are shown in 31 are shown in Figure 11 . Figure 11Among them, the resonance signal with a chemical shift of -30 ± 3 ppm represents the tetracoordinate phosphorus species formed after the stable framework aluminum species, and the resonance signal of -40 ± 3 ppm represents the condensed pentacoordinate phosphorus species. The signal peak area ratio of -30 ± 3 ppm / -40 ± 3 ppm is shown in Table 10.

[0142] Figure 12 For 27 the spectrum of Al MAS-NMR.

[0143] The relative crystallinity and crystallization retention of the phosphorus-modified ZSM-5 molecular sieve samples TCB-4, the comparative sample DPB-7, the comparative sample JCB-5, the sample TCB-5, the comparative sample DPB-8, and the comparative sample JCB-6 before and after hydrothermal aging treatment at 800 °C, 100% water vapor, and 17 h are shown in Table 11.

[0144] For the phosphorus-modified ZSM-5 molecular sieve samples TCB-4, the comparative sample DPB-7, the comparative sample JCB-5, the sample TCB-5, the comparative sample DPB-8, and the comparative sample JCB-6 after being washed with water, the phosphorus content retention rate is shown in Table 12.

[0145] Table 10

[0146] Sample Signal peak area ratio of -30±3 ppm / -40±3 ppm 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 Retention rate of phosphorus content / % 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 by the following process:

[0153] 1. NJ1: 1.91 kg of pseudo-boehmite (containing 1.19 kg of Al2O3), 0.56 kg of kaolin (dry basis 0.5 kg) were slurried with 3.27 kg of deionized water for 30 minutes. While stirring, 5.37 kg of concentrated phosphoric acid (mass concentration 85%) was added to the slurry, and the addition rate of phosphoric acid was 0.04 kg of phosphoric acid / minute / kg of alumina source. The temperature was raised to 70 °C, and then the reaction was carried out 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: According to 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 of Example 1, add deionized water and beat for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH value of the slurry to 3.0, then continue to beat for 45 minutes, then add the phosphorus - aluminum inorganic binder NJ1, stir for 30 minutes, and then spray - dry the obtained slurry to obtain microspheres. Calcinate the microspheres at 500 °C for 1 hour to prepare a cracking catalyst, numbered Cat1.

[0159] Replace the phosphorus - modified ZSM - 5 molecular sieve sample TCB - 1 of Example 1 with the phosphorus - modified ZSM - 5 molecular sieve sample TRCB - 1 of Example 2 respectively, and through the same above - mentioned preparation process, prepare a cracking catalyst, numbered Cat2.

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

[0161] Comparative Examples 14, 15, 16

[0162] Same as the preparation process and material ratio of Example 9, the difference is that the phosphorus - modified ZSM - 5 molecular sieve comparative samples DPB - 1, DPB - 2, and JCB - 1 of Comparative Examples 1, 2, and 3 are used to replace the phosphorus - modified ZSM - 5 molecular sieve sample TCB - 1 respectively, and comparative cracking catalysts, numbered DCat1, DCat2, and DCat3, are prepared respectively.

[0163] Examples 11 - 12

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

[0165] Replace the molecular sieve TCB - 2 with the phosphorus - modified molecular sieve TRCB - 2 of Example 4, and through the same above - mentioned preparation process, prepare a cracking catalyst, numbered Cat4 respectively.

[0166] In the material ratio of cracking catalysts Cat3 and Cat4, based on the dry weight, the 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] Same as the preparation process and material ratio of Example 11, except that the phosphorus-modified molecular sieves DPB-3, DPB-4, and JCB-2 of Comparative Examples 4, 5, and 6 are used to replace the molecular sieve TCB-2, respectively. Comparative cracking catalysts numbered DCat4, DCat5, and DCat6 are prepared 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 of Example 5, add deionized water and aluminum sol and beat for 120 minutes to obtain a slurry with a solid content of 30% by weight. Add hydrochloric acid to adjust the pH value of the slurry to 3.0, then continue to beat for 45 minutes, then add the phosphorus-aluminum inorganic binder NJ2, stir for 30 minutes, and then spray-dry the obtained slurry to obtain microspheres. Bake the microspheres at 500 °C for 1 hour to prepare a cracking catalyst numbered Cat5.

[0171] Replace the molecular sieve TCB-3 with the phosphorus-modified molecular sieve TRCB-3 of Example 6, and prepare a cracking catalyst numbered Cat6 according to the above preparation process.

[0172] In the material ratio of cracking catalysts Cat5 and Cat6, based on the dry weight, the 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] Same as the preparation process and material ratio of Example 13, except that the phosphorus-modified ZSM-5 molecular sieve comparative samples DPB-5, DPB-6, and JCB-4 of Comparative Examples 7, 8, and 9 are used to replace the molecular sieve TCB-3, respectively. Comparative cracking catalysts numbered DCat7, DCat8, and DCat9 are prepared respectively.

[0175] Example 15

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

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

[0178] Comparative Examples 23 and 24

[0179] Same as the preparation process and material ratio of Example 15, the difference is that the phosphorus-modified ZSM-5 molecular sieve comparative samples DPB-7 and JCB-5 of Comparative Examples 10 and 11 are used to replace TCB-4 respectively to prepare comparative cracking catalysts, numbered DCat10 and DCat11.

[0180] Example 16

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

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

[0183] Comparative Examples 25 and 26

[0184] Same as the preparation process and material ratio of Example 16, the difference is that the phosphorus-modified ZSM-5 molecular sieve comparative samples DPB-8 and JCB-6 of Comparative Examples 12 and 13 are 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 respectively subjected to an aging treatment for 17 hours at 800 °C under a 100% steam atmosphere. The aged catalysts were loaded into a fixed-bed micro-reactor to evaluate the catalytic cracking ability of the catalysts for light hydrocarbons. The evaluation conditions were a reaction temperature of 650 °C, a regeneration temperature of 620 °C, and a catalyst-to-oil ratio of 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] Item Light hydrocarbon <![CDATA[Density (20 °C) / (kg·m -3 )]]> 670.7 Element mass composition / % C 83.81 H 16.19 <![CDATA[S / mg.L -1 > 2.6 <![CDATA[N / mg.L -1 > <0.3 Distillation range / °C 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-alkane 72.69 iso-alkane 25.48 Olefin 0.13 Naphthene 1.56 Aromatic hydrocarbon 0.17 Total 100.03

[0192] Comparative Examples 27, 28, and 29

[0193] Same as Example 17, except that the comparative cracking catalysts DCat1, DCat2, and DCat3 were used to replace Cat1, respectively.

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

[0195] Table 15

[0196]

[0197]

[0198] Examples 19 - 20

[0199] The cracking catalysts Cat3 - Cat4 were respectively subjected to an aging treatment for 17 hours at 800 °C under a 100% steam atmosphere. The aged catalysts were loaded into a fixed-bed micro-reactor to evaluate the catalytic cracking ability of the catalysts for light hydrocarbons. The evaluation conditions were a reaction temperature of 650 °C, a regeneration temperature of 620 °C, and a catalyst-to-oil ratio of 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 the comparative cracking catalysts DCat4, DCat5, and DCat6 were used to replace Cat3, 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 respectively subjected to an aging treatment for 17 hours at 800 °C under a 100% steam atmosphere. The aged cracking catalysts were loaded into a fixed - bed micro - reactor to evaluate the catalytic cracking ability of the catalysts for light hydrocarbons. The evaluation conditions were a reaction temperature of 650 °C, a regeneration temperature of 620 °C, and a catalyst - to - oil ratio of 3.2.

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

[0209] Comparative Examples 33, 34, 35

[0210] Same as Example 21, except that the comparative cracking catalysts DCat7, DCat8, and DCat9 were used to replace Cat5 respectively.

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

[0212] Table 17

[0213]

[0214] Examples 23 - 24

[0215] The cracking catalysts Cat7 - Cat8 were respectively subjected to an aging treatment for 17 hours at 800 °C under a 100% steam atmosphere. The aged catalysts were loaded into a fixed - bed micro - reactor to evaluate the catalytic cracking ability of the catalysts for light hydrocarbons. The evaluation conditions were a reaction temperature of 650 °C, a regeneration temperature of 620 °C, and a catalyst - to - oil ratio of 3.2.

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

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

[0218] Same as Example 23, except that the comparative catalysts DCat10, DCat11, DCat12, and DCat13 were used to replace Cat7 respectively.

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

[0220] Table 18

[0221]

[0222] As can be seen from Tables 16, 17, and 18, the cracking catalysts prepared by modifying ZSM - 5 zeolite with phosphorus - containing compounds with a phosphorus valence state of +1 after low - temperature calcination are all better than the cracking catalysts prepared by modifying ZSM - 5 zeolite with phosphorus - containing compounds with a phosphorus valence state of +5 and phosphorus - containing compounds with a phosphorus valence state of +1 after high - temperature calcination. In the catalytic cracking reaction, the hydrocarbon conversion rate increases, and the yields of ethylene and propylene increase.

Claims

1. A catalytic cracking method, which is to carry out a contact reaction between hydrocarbon oil and a cracking catalyst under catalytic cracking reaction conditions. Based on dry basis weight, the cracking catalyst contains 2-20% of Y-type molecular sieve, 3-80% of phosphorus-modified ZSM-5 molecular sieve, 1-70% of inorganic binder and 2-60% of clay, and is characterized in that, The described phosphorus-modified ZSM-5 molecular sieve, its 31 In the PMAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5 to -20 ppm.

2. The method according to claim 1, characterized in that, The cracking catalyst is used alone, or the cracking catalyst forms a mixture with other cracking catalysts. In the mixture, the cracking catalyst accounts for no more than 30% by weight of the total amount of the mixture, preferably 1-25% by weight, more preferably 3-15% by weight.

3. The method according to claim 1, wherein, The catalytic cracking reaction conditions include a reaction temperature of 500-800 °C.

4. The method according to claim 1, wherein The hydrocarbon oil is selected from one or more of crude oil, naphtha, gasoline, atmospheric residue, vacuum residue, atmospheric gas oil, vacuum gas oil, straight-run gas oil, propane light / heavy deoiled oil, coker gas oil, and coal liquefaction products.

5. The method according to claim 1, wherein, 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.

6. The method according to claim 1, wherein After the phosphorus-modified ZSM-5 molecular sieve is hydrothermally aged for 17 h under the conditions of 800 °C and 100% water vapor, 31 In the P MAS-NMR spectrum, the ratio of the peak area of the resonance signal with a chemical shift of -30 ± 3 ppm to the peak area of the resonance signal with a chemical shift of -40 ± 3 ppm > 1, preferably 1.05 to 1.4, more preferably 1.1 to 1.

3.

7. The method according to claim 1, characterized in that, After the phosphorus-modified ZSM-5 molecular sieve is hydrothermally aged for 17 h under the conditions of 800 °C and 100% water vapor, 27 In the Al MAS-NMR spectrum, resonance signal peaks with chemical shifts of 39 ± 3 ppm and -12 ± 3 ppm appear simultaneously.

8. The method according to claim 1, wherein After the phosphorus-modified ZSM-5 molecular sieve is washed with hot water at 70 °C for 2 h, the retention rate of phosphorus content is higher than 50%, about 51-75%. The definition of the retention rate of phosphorus content is P2O5 before washing / P2O5 after washing, calculated as a mass percentage.

9. A cracking catalyst, based on dry basis weight, contains 2-20% of Y-type molecular sieve, 3-80% of phosphorus-modified ZSM-5 molecular sieve, 1-70% of inorganic binder and 2-60% of clay, characterized in that, The phosphorus-modified ZSM-5 molecular sieve, wherein 31 in the PMAS-NMR spectrum, the chemical shift range where resonance signal peaks appear is 5 to -20 ppm.

10. The cracking catalyst according to claim 9, characterized in that, After the phosphorus-modified ZSM-5 molecular sieve is hydrothermally aged for 17 h under the conditions of 800 °C and 100% water vapor, 31 In the P MAS-NMR spectrum, the ratio of the peak area of the resonance signal with a chemical shift of -30 ± 3 ppm to the peak area of the resonance signal with a chemical shift of -40 ± 3 ppm > 1, preferably 1.05 - 1.4, more preferably 1.1 - 1.

3.

11. The cracking catalyst according to claim 9, wherein, After the phosphorus-modified ZSM-5 molecular sieve is hydrothermally aged for 17 h under the conditions of 800 °C and 100% water vapor, 27 In the spectrum of Al MAS-NMR, resonance signal peaks with chemical shifts of 39 ± 3 ppm and -12 ± 3 ppm appear simultaneously.

12. The cracking catalyst according to claim 9, wherein, After the phosphorus-modified ZSM-5 molecular sieve is washed with hot water at 70 °C for 2 h, the retention rate of phosphorus content is higher than 50%, about 51-75%. The definition of the retention rate of phosphorus content is P2O5 before washing / P2O5 after washing, calculated as a mass percentage.

13. The cracking catalyst according to claim 9, characterized in that, For the phosphorus-modified ZSM-5 molecular sieve, when both phosphorus and aluminum are in terms of moles, the ratio of the two is 0.01-5, preferably 0.1-3.

14. The cracking catalyst according to claim 9, characterized in that, The phosphorus-modified ZSM-5 molecular sieve is obtained by modifying with a phosphorus-containing compound with a phosphorus valence state of +1 and including a step of air calcination at 300-400 °C.

15. The cracking catalyst according to claim 1, characterized in that, For the phosphorus-modified ZSM-5 molecular sieve, when both phosphorus and aluminum are in terms of moles, the ratio of the two is 0.01-5, preferably 0.1-3.

16. The cracking catalyst according to claim 1, wherein The phosphorus-modified ZSM-5 molecular sieve is obtained by modifying with a phosphorus-containing compound with a phosphorus valence state of +1 and including a step of air calcination at 300-400 °C.

17. The cracking catalyst according to claim 16, wherein The phosphorus-modified ZSM-5 molecular sieve is obtained by contacting and impregnating the HZSM-5 molecular sieve with an aqueous solution of a phosphorus-containing compound with a phosphorus valence 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 obtained by mixing and grinding the HZSM-5 molecular sieve with a solid phosphorus-containing compound with a phosphorus valence state of +1, cooling to 20-25 °C, and then air calcining at 300-400 °C.

18. The cracking catalyst according to claim 17, wherein For the impregnation, the weight ratio of water to sieve is 0.5-2, and it is carried out at room temperature for 0.5-10 hours; for the drying, the atmosphere is air, and it is carried out at 100-120 °C for 2-24 hours; for the air calcination, it is carried out at 330-370 °C, such as 350 °C, for 0.5-12 hours.

19. The cracking catalyst according to claim 17, wherein For the heating and melting treatment, the temperature is higher than the melting point temperature of the solid phosphorus-containing compound and lower than the temperature at which the solid phosphorus-containing compound decomposes or dehydrates, and the treatment time is 2-72 hours.

20. The cracking catalyst according to claim 17, wherein The phosphorus-valence +1 phosphorus-containing compound is selected from one or more of hypophosphorous acid, ammonium hypophosphite, and hypophosphite; alternatively, the aqueous solution of the phosphorus-valence +1 phosphorus-containing compound is obtained by adjusting the pH value of an aqueous solution of hypophosphorous acid to 5-9 with ammonia water.

21. The cracking catalyst according to claim 17, wherein, The molar ratio of the HZSM-5 molecular sieve to the phosphorus-valence +1 phosphorus-containing compound is (0.1-2.5):1, preferably (0.5-1.5):1, where the HZSM-5 molecular sieve is calculated based on aluminum and the phosphorus-containing compound is calculated based on phosphorus.

22. The cracking catalyst according to claim 9, wherein, The inorganic binder includes a phosphoaluminum inorganic binder, and based on the dry basis of the catalyst, the phosphoaluminum inorganic binder is 5-40% by weight.

23. The cracking catalyst according to claim 9 or 22, wherein, The inorganic binder further contains at least one selected from pseudoboehmite, aluminum sol, silica-alumina sol, and water glass.

24. The cracking catalyst according to claim 9, wherein, The clay is selected from at least one of kaolin, sepiolite, attapulgite, rectorite, montmorillonite, and diatomite.

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