A method for preparing an MTO catalyst

Abstract

The application discloses a preparation method of MTO catalyst. The method comprises the following steps: a) treating a phosphosilicate aluminosilicate molecular sieve in a titanium acid ester-containing alcohol solution, and drying to obtain a modified molecular sieve; b) mixing the modified molecular sieve obtained in the step a), a liquid medium, a matrix material, a structure reinforcing material and a binder to form a suspension; the structure reinforcing material is ceramic fiber with a diameter of 2-6 microns and a length-diameter ratio of 1-15; c) high-speed shearing the suspension obtained in the step b), and spray drying to obtain a microsphere catalyst; and d) calcining the microsphere catalyst obtained in the step c) to obtain a finished catalyst. The catalyst solves the problems of poor catalytic performance and high abrasion index of the fluidized bed catalyst in the prior art.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation, and more specifically to a method for preparing an MTO catalyst. Background Technology

[0002] Methanol-to-olefins (MTO) is a process technology that uses methanol, typically produced from natural gas or coal, to produce low-carbon olefins such as polymer-grade ethylene and propylene under the action of a catalyst. The MTO route has attracted widespread attention due to the large-scale, inexpensive, and convenient availability of syngas as a feedstock. In recent years, dozens of MTO plants have been put into commercial operation, achieving significant economic and social benefits.

[0003] The core of methanol-to-olefins (MTO) technology lies in the development of molecular sieve catalysts. Early catalysts used in MTO were mostly silica-alumina zeolite molecular sieves, such as ZSM-5. However, their relatively large pore size and strong acidity resulted in low yields of low-carbon olefins. In 1982, Union Carbide Corporation (UCC) first synthesized the SAPO series of silica-alumina phosphate molecular sieves. Among them, SAPO-34 molecular sieve is the most noteworthy. It possesses a chalcogenide-like structure, along with small pore size, moderate acidity, and strong hydrothermal stability. It exhibits excellent selectivity for low-carbon olefins in the catalytic reaction of methanol to low-carbon olefins, thus attracting widespread attention from researchers both domestically and internationally.

[0004] When molecular sieves are used in industrial catalysis, they generally cannot be prepared as catalysts using 100% molecular sieves. Firstly, molecular sieves have poor binding properties and excessively fine particle size, making them difficult to mold into catalysts directly applicable to industrial processes. Secondly, the manufacturing cost of molecular sieves is generally high; using 100% molecular sieves as industrial catalysts would increase costs. Since most MTO processes utilize fluidized bed reactors, current technologies typically involve directly preparing a suspension of molecular sieves with binders and liquid media, followed by shearing, drying, and calcination to create microsphere fluidized bed catalysts.

[0005] In summary, although some existing patents address the issue of improving the wear resistance of fluidized bed catalysts, the wear resistance of fluidized bed catalysts still needs to be further improved, while also ensuring that the catalyst's catalytic performance does not decline and that production energy consumption does not increase. Summary of the Invention

[0006] The technical problem this invention aims to solve is the poor wear resistance and low selectivity for ethylene and propylene found in existing molecular sieve fluidized bed catalysts. This invention provides a method for preparing an MTO catalyst. The catalyst prepared by this method exhibits high wear resistance and good selectivity for ethylene and propylene.

[0007] The first aspect of this invention provides a method for preparing an MTO catalyst, comprising:

[0008] a) The silica-alumina molecular sieve was treated in an alcohol solution containing titanate and dried to obtain the modified molecular sieve.

[0009] b) The modified molecular sieve obtained in step a), liquid medium, matrix material, structural reinforcing material and binder are mixed to form a suspension; the structural reinforcing material is ceramic fiber with a diameter of 2 to 6 μm and an aspect ratio of 1 to 15;

[0010] c) The suspension obtained in the high-speed shearing step b) is spray-dried to obtain the microsphere catalyst;

[0011] d) Calcining the microsphere catalyst obtained in step c) yields the catalyst.

[0012] According to one aspect of the present invention, the processing method in step a) involves mixing and stirring a molecular sieve and a titanate-containing alcohol solution at a certain weight ratio, followed by processing. The weight ratio of the molecular sieve to the titanate-containing alcohol solution is 10–40:100, preferably 10–30:100; the processing temperature is 30–90°C, preferably 50–90°C; and the processing time is 30–90 minutes, preferably 30–50 minutes.

[0013] According to one aspect of the present invention, after the treatment in step a), conventional filtration and washing operations are performed before drying. The drying conditions are: temperature of 80–130°C and time of 0.5–12 h.

[0014] According to one aspect of the invention, the molecular sieve in step a) is washed with water and then subjected to solid-liquid separation before being treated with an alcohol solution containing titanate, and the resulting solid is not dried.

[0015] According to one aspect of the invention, deionized water is added to an alcohol solution containing titanate, wherein the weight ratio of titanate, alcohol and water satisfies the following conditions: titanate: alcohol = 1 to 4: 100, and deionized water: alcohol = 1 to 5: 100.

[0016] According to one aspect of the invention, the titanate is selected from at least one of tetrabutyl titanate and tetraisopropyl titanate, preferably tetrabutyl titanate (purity ≥ 98 wt%).

[0017] According to one aspect of the invention, the alcohol is selected from at least one of ethanol and isopropanol, preferably ethanol.

[0018] According to one aspect of the present invention, the silica-alumina molecular sieve is selected from at least one of SAPO-18 and SAPO-34, preferably SAPO-34; the Si / Al molar ratio of the SAPO-34 molecular sieve is 0.05 to 0.5:1, and the Si / Al molar ratio of the SAPO-18 molecular sieve is 0.1 to 0.3.

[0019] According to one aspect of the invention, the structural reinforcing material is ceramic fiber, which is an ultrafine fiber formed by spinning a mixture of electrofused alumina and silica, wherein the mass content of Al2O3+SiO2 is ≥98.0%.

[0020] According to one aspect of the present invention, the ceramic fibers need to be pretreated in a phosphoric acid solution of 0.1–0.3 mol / L for 0.5–2.0 hours. The weight ratio of ceramic fibers to phosphoric acid solution is 20–60:100, and the pretreatment is carried out under stirring conditions at a temperature of 20–30°C. After pretreatment, the fibers are obtained by conventional filtration, washing, and drying to obtain the pretreated ceramic fibers.

[0021] According to one aspect of the present invention, the solid content of the suspension in step b) is preferably 20-50%, and the pH value is preferably 2.5-5.5.

[0022] According to one aspect of the invention, in step b), the binder is a sol, the matrix material is clay and / or hydrotalcite, and the liquid medium is deionized water.

[0023] According to one aspect of the invention, in step b), the binder is preferably silica sol or alumina sol; the matrix material is clay and / or hydrotalcite, preferably selected from at least one of kaolin, bentonite and hydrotalcite, and more preferably kaolin.

[0024] According to one aspect of the invention, in step b) the suspension, by weight percentage: molecular sieve is preferably 5-40% by weight; binder is preferably 1-20% by weight; matrix material is preferably 5-50% by weight; liquid medium is preferably 10-88% by weight; and structural reinforcing material is preferably 1-10% by weight.

[0025] According to one aspect of the invention, in step b) the suspension, by weight percentage: molecular sieve more preferably 10-30% by weight; binder more preferably 1-10% by weight; matrix material more preferably 10-40% by weight; liquid medium more preferably 15-77% by weight; and structural reinforcing material more preferably 2-8% by weight.

[0026] According to one aspect of the invention, in step c), the particle size of 90% of the particles in the mixture that are rapidly sheared to the point of origin is preferably less than 5 micrometers.

[0027] According to one aspect of the present invention, the spray drying conditions in step c) are: inlet temperature of 180-300°C, outlet temperature of 100-160°C, and centrifugal speed of 5000-15000 rpm.

[0028] According to one aspect of the present invention, in step d), the calcination temperature is 500-900°C, preferably 550-750°C, the calcination time is 0.5-24 hours, preferably 4-12 hours, and the calcination atmosphere is a flowing atmosphere, preferably flowing air, with the flow driving force coming from a vacuum.

[0029] According to one aspect of the present invention, the catalyst prepared by spray drying, after being calcined at high temperature, has an attrition index of less than 1.00 wt% / h, preferably less than 0.50 wt% / h, more preferably less than 0.30 wt% / h, and even more preferably 0.16 to 0.19 wt% / h.

[0030] According to one aspect of the invention, the catalyst obtained in step d) has an average particle size of 70-130 micrometers, preferably 80-100 micrometers.

[0031] According to one aspect of the invention, in the catalyst obtained in step d), the content of TiO2, calculated as Ti, is 0.500%-1.500% based on the weight of the catalyst.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] 1. The MTO catalyst of this invention exhibits high catalytic performance and a low attrition index. When applied to the methanol-to-olefins reaction, it demonstrates high selectivity for low-carbon olefins and a low attrition index. While ensuring the catalytic performance of the MTO fluidized bed catalyst, it achieves a high-attrition-resistant fluidized bed catalyst without significantly increasing the catalyst production cost.

[0034] 2. Existing hydrothermal synthesis methods produce silica-alumina phosphate molecular sieves with crystal sizes only a few hundred nanometers. During the drying process of the molecular sieve powder, the high surface energy molecular sieve crystals are prone to agglomeration. The agglomerated molecular sieve crystals, within the spray-formed catalyst microspheres, cause localized stress differences due to uneven distribution between the molecular sieve and the matrix material, leading to a decrease in the catalyst's wear resistance. In this invention, the surface of the silica-alumina phosphate molecular sieve is modified with tetrabutyl titanate before drying. The modified molecular sieve is less prone to agglomeration. Simultaneously, ceramic fibers are added during the slurry preparation process of catalyst spray drying. This not only yields a more uniform slurry but also strengthens the structure of the spherical structure formed by sintering molecular sieve, kaolin, and alumina sol, resulting in a silica-alumina phosphate fluidized bed catalyst with a low wear index. In addition, the TiO2 generated by calcining the titanate on the surface of the molecular sieve grains can reduce the micro-stress between the grains and the matrix material and improve the grain boundary bonding strength, which is one of the reasons why the catalyst prepared in this invention has higher wear resistance. Attached Figure Description

[0035] Figure 1 The XRD pattern of the SAPO-34 molecular sieve obtained in Example 5;

[0036] Figure 2 The XRD pattern of the SAPO-18 molecular sieve obtained in Example 9;

[0037] Figure 3 SEM image of the internal structure of the molecular sieve fluidized bed catalyst obtained in Comparative Example 1 after grinding and crushing;

[0038] Figure 4 This is a SEM image of the internal structure of the molecular sieve fluidized bed catalyst obtained in Example 1 after grinding and crushing.

[0039] Figure 5 This is a SEM image of the molecular sieve fluidized bed catalyst obtained in Example 1. Detailed Implementation

[0040] The wear index described in this invention was determined on a VINCI D5757-11 fluidized bed wear tester, using the method described in Chapter 7 of Q / SH 361.552-2017.

[0041] In this invention, the wear index ω The value is expressed as a mass fraction per hour (% / h) and is calculated using the following formula:

[0042]

[0043] In the formula:

[0044] m5 — The mass of the powder collection system after 5 hours, expressed in grams (g);

[0045] m1 — The mass of the powder collection system after 1 hour, in grams (g);

[0046] m — the numerical value of the sample mass, in grams (g);

[0047] m0 — The mass of the powder collection system before the test, in grams (g);

[0048] 4 — The unit is h.

[0049] The arithmetic mean of the two measurements was taken as the analytical result, and rounded according to GB / T 8170 to an accuracy of 0.01% / h.

[0050] The average particle size of the catalyst described in this invention was determined by a laser particle size analyzer (model: Malvern 2000).

[0051] The present invention does not have any particular limitation on the high-speed shearing, and it can be carried out in accordance with conventional technical means in the field, which will not be elaborated here.

[0052] The morphology of the catalyst described in this invention was determined using a Philips XL300 scanning electron microscope.

[0053] The internal structure of the catalyst described in this invention was determined using a Philips XL300 scanning electron microscope. The catalyst was ground into fragments to observe its internal structure.

[0054] The Ti content in the catalyst described in this invention was tested using ICP. Instrument parameters: Varian 725ES; Test method: Standard curve method. Test conditions are shown in Table 1.

[0055] Table 1

[0056] name Technical parameters name Technical parameters Plasma power 1100W Injection time 45s Ar plasma <![CDATA[15L min -1 ]]> Reading time 5s Auxiliary gas (Ar) <![CDATA[1.5L min -1 ]]> Sample injection pump speed 15rpm Atomizer flow rate <![CDATA[0.75L min -1 ]]> Observation mode radial observation height 10mm Ti wavelength measurement 336.122nm

[0057] The present invention will be described in detail below through embodiments.

[0058] The reagents used in the following examples are commercially available and of analytical grade.

[0059]

Preparation Example 1

[0060] This preparation example illustrates the preparation of the tetrabutyl titanate ethanol solution described in this invention:

[0061] Weigh out 100 parts of ethanol solution and 4 parts of tetrabutyl titanate by weight. Add the tetrabutyl titanate dropwise to the ethanol solution while stirring. Weigh out 5 parts of deionized water and add it to the above solution. Continue stirring until homogeneous.

[0062]

Preparation Example 2

[0063] This preparation example illustrates the preparation of the tetrabutyl titanate ethanol solution described in this invention:

[0064] Weigh 100 parts of ethanol solution and 1 part of tetrabutyl titanate by weight. Add the tetrabutyl titanate dropwise to the ethanol solution while stirring. Weigh 2 parts of deionized water and add them to the above solution. Continue stirring until homogeneous.

[0065]

Preparation Example 3

[0066] This preparation example illustrates the preparation of the tetrabutyl titanate ethanol solution described in this invention:

[0067] Weigh 100 parts of ethanol solution and 2 parts of tetrabutyl titanate by weight. Add the tetrabutyl titanate dropwise to the ethanol solution while stirring. Weigh 3 parts of deionized water and add them to the above solution. Continue stirring until homogeneous.

[0068]

Preparation Example 4

[0069] This preparation example illustrates the preparation of the isopropyl titanate isopropanol solution described in this invention:

[0070] Weigh 100 parts of ethanol solution and 2 parts of isopropyl titanate by weight. Add isopropyl titanate dropwise to the isopropanol solution while stirring. Weigh 3 parts of deionized water and add it to the above solution. Continue stirring until homogeneous.

[0071]

Preparation Example 5

[0072] This preparation example illustrates the preparation of the SAPO-34 molecular sieve described in this invention:

[0073] Weigh out 12.0 parts γ-Al2O3 and 35.0 parts deionized water and mix them evenly to form solution a; mix 23.1 parts phosphoric acid (85% by weight) and 37.5 parts deionized water evenly to form solution b; after mixing a and b, stir at room temperature for 2 hours to form a homogeneous solution c; while stirring, add 20.2 parts triethylamine, 15 parts tetraethylammonium hydroxide (TEAOH), 4.5 parts silica sol (40% by weight) and 10.0 parts deionized water to c in sequence, and stir thoroughly to obtain mixture A.

[0074] Mixture A was placed in a crystallization vessel and heated to 200°C with stirring. After crystallization for 24 hours, the solid product was recovered by solid-liquid separation. The solid product was washed three times with deionized water and then dried. XRD characterization showed that the obtained product was pure phase SAPO-34 (Si / Al molar ratio of 0.15).

[0075]

Preparation Example 6

[0076] This preparation example illustrates the pretreatment preparation of the ceramic fibers described in this invention:

[0077] Weigh 1 part of ceramic fiber cotton (5 μm in diameter, aspect ratio of 1.2 to 6) and 5 parts of 0.1 mol / L phosphoric acid solution, stir at 25°C for 1.0 hour, filter, wash, and dry to obtain pretreated ceramic fiber.

[0078]

Preparation Example 7

[0079] This preparation example illustrates the pretreatment preparation of the ceramic fibers described in this invention:

[0080] Weigh 1 part of ceramic fiber cotton (diameter 4μm, aspect ratio 1.5-7) and 5 parts of 0.1 mol / L phosphoric acid solution, stir at 25℃ for 2.0 hours, filter, wash, and dry to obtain pretreated ceramic fiber.

[0081] Preparation Example 88

[0082] This preparation example illustrates the pretreatment preparation of the ceramic fibers described in this invention:

[0083] Weigh 1 part of ceramic fiber cotton (diameter 2μm, aspect ratio 4-15) and 3 parts of 0.2 mol / L phosphoric acid solution, stir at 25℃ for 0.5 hours, filter, wash, and dry to obtain pretreated ceramic fiber.

[0084]

Example 1

[0085] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 1 at a weight ratio of 20:100 without drying. The mixture was stirred at 60°C for 30 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 6 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0086] The raw materials were weighed according to the following proportions: 16% (by weight) of the modified SAPO-34 molecular sieve; 18% (by weight) of kaolin; 4% (by weight) of alumina sol; 2% (by weight) of ceramic fiber obtained in Preparation Example 6; and 60% (by weight) of deionized water. Except for water, all raw material proportions here are dry weight ratios. First, the modified SAPO-34 molecular sieve and a certain amount of water were mixed and stirred for 1 hour. After high-speed shearing for 15 minutes, a uniform molecular sieve suspension was formed. Alumina sol was added to the suspension, and the mixture was rapidly stirred for 15 minutes, followed by high-speed shearing for 15 minutes. Kaolin was added, and the mixture was stirred for 30 minutes. Ceramic fiber slurry was added, and the mixture was stirred for 15 minutes, followed by high-speed shearing for 45 minutes to obtain a suspension with a solid content of 40% and a pH of 2.9. 90% of the particles in this suspension were smaller than 3.6 micrometers. The suspension was spray-dried (inlet temperature 290℃, outlet temperature 140℃, centrifugation speed 10000 rpm) and then calcined in air at 600℃ for 6 hours to obtain a molecular sieve fluidized bed catalyst.

[0087] The average particle size and TiO2 content of the catalyst obtained in Example 1 are shown in Table 2.

[0088]

Example 2

[0089] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 1 at a weight ratio of 20:100 without drying. The mixture was stirred at 30°C for 30 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 6 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0090] The raw materials were weighed according to the following proportions: 16 wt% of the modified SAPO-34 molecular sieve; 17 wt% of kaolin; 3 wt% of alumina sol; 4 wt% of the ceramic fiber obtained in Preparation Example 6; and 60 wt% of deionized water. Except for water, all raw material proportions here are dry weight ratios. First, the modified SAPO-34 molecular sieve and a certain amount of water were mixed and stirred for 1 hour, followed by high-speed shearing for 15 minutes to form a uniform molecular sieve suspension. Alumina sol was added to the suspension, and the mixture was rapidly stirred for 15 minutes, followed by high-speed shearing for 15 minutes. Kaolin was added, and the mixture was stirred for 30 minutes. Ceramic fiber slurry was added, and the mixture was stirred for 15 minutes, followed by high-speed shearing for 45 minutes to obtain a suspension with a solid content of 39.8% and a pH of 3.2. 90% of the particles in this suspension were smaller than 3.8 micrometers. The suspension was spray-dried (same as in Example 1) and then calcined at 600°C for 6 hours under air conditions to obtain a molecular sieve fluidized bed catalyst.

[0091] The average particle size and TiO2 content of the catalyst obtained in Example 2 are shown in Table 2.

[0092]

Example 3

[0093] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 1 at a weight ratio of 20:100 without drying. The mixture was stirred at 90°C for 30 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 6 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0094] The raw materials were weighed according to the following proportions: 16 wt% of the modified SAPO-34 molecular sieve; 15 wt% of kaolin; 3 wt% of alumina sol; 6 wt% of the ceramic fiber obtained in Preparation Example 6; and 60 wt% of deionized water. Except for water, all raw material proportions here are dry weight ratios. First, the modified SAPO-34 molecular sieve and a certain amount of water were mixed and stirred for 1 hour, followed by high-speed shearing for 15 minutes to form a uniform molecular sieve suspension. Alumina sol was added to the suspension, and the mixture was rapidly stirred for 15 minutes, followed by high-speed shearing for 15 minutes. Kaolin was added, and the mixture was stirred for 30 minutes. Ceramic fiber slurry was added, and the mixture was stirred for 15 minutes, followed by high-speed shearing for 45 minutes to obtain a suspension with a solid content of 40% and a pH of 3.0. 90% of the particles in this suspension were smaller than 3.8 micrometers. The suspension was spray-dried (same as in Example 1) and then calcined at 600°C for 6 hours under air conditions to obtain a molecular sieve fluidized bed catalyst.

[0095] The average particle size and TiO2 content of the catalyst obtained in Example 3 are shown in Table 2.

[0096]

Example 4

[0097] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 1 at a weight ratio of 40:100 without drying. The mixture was stirred at 90°C for 30 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 8 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0098] The raw materials were weighed according to the following proportions: 14 wt% of the modified SAPO-34 molecular sieve described above; 18 wt% of kaolin; 4 wt% of alumina sol; 4 wt% of the ceramic fiber obtained in Preparation Example 7; and 60 wt% of deionized water. Except for water, all raw material proportions here are dry weight ratios. Other aspects are the same as in Example 1.

[0099] The average particle size and TiO2 content of the catalyst obtained in Example 4 are shown in Table 2.

[0100]

Example 5

[0101] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 2 at a weight ratio of 15:100 without drying. The mixture was stirred at 90°C for 60 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 8 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0102] The raw materials were weighed according to the following proportions: 16 wt% of the modified SAPO-34 molecular sieve described above; 18 wt% of kaolin; 4 wt% of alumina sol; 2 wt% of the ceramic fiber obtained in Preparation Example 7; and 60 wt% of deionized water. Except for water, all raw material proportions here are dry weight ratios. Other aspects are the same as in Example 1.

[0103] The average particle size and TiO2 content of the catalyst obtained in Example 5 are shown in Table 2.

[0104]

Example 6

[0105] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 2 at a weight ratio of 10:100 without drying. The mixture was stirred at 60°C for 45 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 8 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0106] The raw materials were weighed according to the following proportions: 15 wt% of the modified SAPO-34 molecular sieve described above; 14 wt% of kaolin; 3 wt% of alumina sol; 8 wt% of the ceramic fiber obtained in Preparation Example 8; and 60 wt% of deionized water. Except for water, all raw material proportions here are dry weight ratios. Other aspects are the same as in Example 1.

[0107] The average particle size and TiO2 content of the catalyst obtained in Example 6 are shown in Table 2.

[0108]

Example 7

[0109] The SAPO-34 molecular sieve prepared by hydrothermal synthesis in Preparation Example 5 was separated into solid and liquid phases. The obtained solid product was washed three times with deionized water and then added to the tetrabutyl titanate ethanol solution obtained in Preparation Example 3 at a weight ratio of 30:100 without drying. The mixture was stirred at 70°C for 45 minutes, filtered to remove the solution, and the obtained solid was washed once with ethanol solution to remove free tetrabutyl titanate. The solid was dried at 110°C for 6 hours to obtain the titanate-modified SAPO-34 molecular sieve.

[0110] The raw materials were weighed according to the following proportions: 16 wt% of the modified SAPO-34 molecular sieve described above; 18 wt% of kaolin; 4 wt% of alumina sol; 2 wt% of the ceramic fiber obtained in Preparation Example 8; and 60 wt% of deionized water. Except for water, all raw material proportions here are dry weight ratios. Other aspects are the same as in Example 1.

[0111] The average particle size and TiO2 content of the catalyst obtained in Example 7 are shown in Table 2.

[0112]

Example 8

[0113] The only difference from Example 1 is that the tetrabutyl titanate ethanol solution of Preparation Example 1 is replaced with the tetraisopropyl titanate isopropanol solution of Preparation Example 4.

[0114] The average particle size and TiO2 content of the catalyst obtained in Example 8 are shown in Table 2.

[0115]

Example 9

[0116] The only difference from Example 1 is that SAPO-34 molecular sieve is replaced with SAPO-18 molecular sieve (Si / Al molar ratio of 0.15).

[0117] The average particle size and TiO2 content of the catalyst obtained in Example 9 are shown in Table 2.

[0118]

Example 10

[0119] The only difference from Example 1 is that the ceramic fibers were not pretreated.

[0120] The average particle size and TiO2 content of the catalyst obtained in Example 10 are shown in Table 2.

[0121] (Comparative Example 1)

[0122] The only difference from Example 1 is that the pure phase SAPO-34 molecular sieve of Preparation Example 5 was used, and no ceramic fibers were added to the suspension.

[0123] The raw materials were weighed according to the following proportions: 16% (by weight) SAPO-34 molecular sieve; 20% (by weight) kaolin; 4% (by weight) alumina sol; and 60% (by weight) deionized water. Except for water, all raw material proportions are dry weight ratios. First, the SAPO-34 molecular sieve and a certain amount of water were mixed and stirred for 1 hour, then subjected to high-speed shearing for 15 minutes. Alumina sol was added, and the mixture was rapidly stirred for 15 minutes, followed by high-speed shearing for 15 minutes. Kaolin was added, and the mixture was stirred for 30 minutes, then subjected to high-speed shearing for 45 minutes to obtain a suspension with a solid content of 38% and a pH of 4.2. 90% of the particles in this suspension were found to be smaller than 3.9 micrometers. The suspension was spray-dried (same as in Example 1) and then calcined in air at 600°C for 6 hours to obtain the molecular sieve fluidized bed catalyst.

[0124] The average particle size and TiO2 content of the catalyst obtained in Comparative Example 1 are shown in Table 2.

[0125] Comparative Example 2

[0126] Compared with Comparative Example 1, the only difference is that the total dry weight of the spray slurry in Comparative Example 1 is considered as 100 parts, and 6 parts of tetrabutyl titanate are added. The re-prepared slurry is spray-dried and calcined to obtain a fluidized bed catalyst of silica-alumina molecular sieve.

[0127] The average particle size and TiO2 content of the catalyst obtained in Comparative Example 2 are shown in Table 2.

[0128] Comparative Example 3

[0129] The only difference from Example 1 is that the pure phase SAPO-34 molecular sieve of Preparation Example 5 was used.

[0130] The average particle size and TiO2 content of the catalyst obtained in Comparative Example 3 are shown in Table 2.

[0131]

Test Example 1

[0132] The fluidized bed catalysts obtained in Examples 1-10 and Comparative Examples 1-3 were subjected to wear index determination on a D5757-11 fluidized bed wear tester, and the results are shown in Table 3.

[0133]

Test Example 2

[0134] The phosphate silica-alumina molecular sieve catalysts obtained in Examples 1-10 and Comparative Examples 1-3 were subjected to methanol-to-olefins reaction in a small fixed fluidized bed. The reaction conditions were: 40 g catalyst, pure methanol feed, and a mass hourly space velocity (WHSV) of 4 h⁻¹. 1 The reaction temperature was 480℃, and the reaction pressure was atmospheric pressure. The reaction results are shown in Table 3.

[0135] Table 2

[0136] Ti content (wt%) Average particle size of catalyst (micrometers) Example 1 0.829 85 Example 2 0.801 85 Example 3 0.897 86 Example 4 0.799 84 Example 5 0.787 88 Example 6 0.932 87 Example 7 0.865 86 Example 8 0.804 85 Example 9 0.825 86 Example 10 0.812 87 Comparative Example 1 0.021 88 Comparative Example 2 0.847 84 Comparative Example 3 0.022 86

[0137] Table 3

[0138]

[0139] The specific embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combining the various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A method for preparing an MTO catalyst, comprising: a) treating a silicoaluminophosphate molecular sieve in a titanium ester-containing alcohol solution, and drying to obtain a modified molecular sieve; b) mixing the modified molecular sieve obtained in step a), a liquid medium, a matrix material, a structure strengthening material, and a binder to form a suspension; the structure strengthening material is ceramic fiber with a diameter of 2-6 μm and an aspect ratio of 1-15; c) high-speed shearing the suspension obtained in step b), and spray drying to obtain a microspheric catalyst; d) calcining the microspheric catalyst obtained in step c) to obtain the catalyst; the silicoaluminophosphate molecular sieve prepared in step a) is subjected to solid-liquid separation after water washing before being treated in the titanium ester-containing alcohol solution, and the obtained solid is not dried; the ceramic fiber in step b) is pretreated in a 0.1-0.3 mol / L phosphoric acid solution for 0.5-2.0 hours.

2. The method of claim 1, wherein: In step a), the treatment method is mixing and stirring the silicoaluminophosphate molecular sieve and the titanium ester-containing alcohol solution at a certain weight ratio, and then treating; the weight ratio of the molecular sieve to the titanium ester-containing alcohol solution is 10-40:100, the treatment temperature is 30-90℃, and the treatment time is 30-90 minutes.

3. The method of claim 2, wherein: In step a), the weight ratio of the molecular sieve to the titanium ester-containing alcohol solution in the treatment method is 10-30:100, the treatment temperature is 50-90℃, and the treatment time is 30-50 minutes.

4. The method of claim 1, wherein: The titanium ester-containing alcohol solution is added with deionized water, and the weight ratio of the titanium ester, alcohol, and water satisfies titanium ester:alcohol = 1-4:100 and deionized water:alcohol = 1-5:

100.

5. The method of claim 1, wherein: The titanium ester is at least one selected from tetrabutyl titanate and tetraisopropyl titanate; the alcohol is at least one selected from ethanol and isopropanol; the silicoaluminophosphate molecular sieve is at least one selected from SAPO-34 and SAPO-18; the Si / Al molar ratio of the SAPO-34 molecular sieve is 0.05-0.5:1, and the Si / Al molar ratio of the SAPO-18 molecular sieve is 0.1-0.

3.

6. The method of claim 5, wherein: The titanium ester is tetrabutyl titanate; the alcohol is ethanol; and the silicoaluminophosphate molecular sieve is SAPO-34 molecular sieve.

7. The method of claim 1, wherein: The pretreatment temperature of the ceramic fiber in the phosphoric acid solution is 20-30℃; and / or, the weight ratio of the ceramic fiber to the phosphoric acid solution is 20-60:

100.

8. The method of claim 1, wherein: In the suspension in step b), the molecular sieve is 5-40% by weight; the binder is 1-20% by weight; the matrix material is 5-50% by weight; the liquid medium is 10-88% by weight; and the structure strengthening material is 1-10% by weight.

9. The method of claim 8, wherein: In the suspension in step b), the molecular sieve is 10-30% by weight; the binder is 1-10% by weight; the matrix material is 10-40% by weight; the liquid medium is 15-77% by weight; and the structure strengthening material is 2-8% by weight.

10. The method of claim 1, wherein: The solid mass content of the suspension in step b) is 20-50%, and the pH value is 2.5-5.5; In step c), the high-speed shearing is performed until 90% of the particle size in the mixed solution is less than 5 μm.

11. The method of claim 1, wherein: In step b), the binder is sol; the matrix material is clay and / or hydrotalcite; and the liquid medium is deionized water.

12. The method of claim 11, wherein: Step b) the binder is a silica sol or an alumina sol; the base material is at least one of kaolin, bentonite and hydrotalcite.

13. The method of claim 12, wherein: Step b) the base material is kaolin.

14. The method of claim 1, wherein: Step d) the calcination temperature is 500-900°C, the calcination time is 0.5-24 hours, and the calcination atmosphere is flowing air.

15. The method of claim 14, wherein: Step d) the calcination temperature is 550-750°C, the calcination time is 4-12 hours.

16. The method of claim 1, wherein: The catalyst prepared by spray drying has an attrition index of less than 1.0 wt% / h after high-temperature calcination.

17. The method of claim 16, wherein: The catalyst prepared by spray drying has an attrition index of less than 0.50 wt% / h after high-temperature calcination.

18. The method of claim 17, wherein: The catalyst prepared by spray drying has an attrition index of less than 0.30 wt% / h after high-temperature calcination.

19. The method of claim 1, wherein: The catalyst prepared in step d) has an average particle size of 70-130 microns.

20. The method of claim 19, wherein: The catalyst prepared in step d) has an average particle size of 80-100 microns.

21. The method of claim 1, wherein: The catalyst prepared in step d) has a TiO2 content of 0.500%-1.500% (calculated as Ti) based on the weight of the catalyst.

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