Titanium silical molecular sieve and preparation method thereof by rolling ball molding

Abstract

The application discloses a kind of titanium silicalite and its preparation method of rolling ball forming, comprising the following steps: S1: after the slurry of titanium silicalite to be rolled into a ball is crystallized, it is obtained by spray drying and calcination that the molecular sieve powder for rolling ball is obtained;S2: the molecular sieve powder prepared in step S1, binder, water, lubricant are mixed to obtain once-formed wet ball by rolling ball;S3: the once-formed wet ball prepared in step S2 is mixed with the molecular sieve powder prepared in step S1, binder, water and lubricant, and then secondary forming is carried out by rolling ball to obtain secondary forming wet ball;S4: the secondary forming wet ball prepared in step S3 is dried and calcined to obtain the final titanium silicalite after rolling ball forming.The application optimizes the uniformity and size control of rolling ball by step forming combined with the use of lubricant, avoids cracking or deformation, and the small ball prepared by the method has high strength and uniform particle size, and has good application in olefin epoxidation.

Description

Technical Field

[0001] This invention belongs to the field of titanium-silicon molecular sieve spheroidizing technology, and in particular relates to a titanium-silicon molecular sieve and a method for preparing the spheroidizing process. Background Technology

[0002] TS-1 is a Pentasil-type heteroatom molecular sieve containing titanium atoms in its framework. In addition to maintaining the original topology of MFI molecular sieves, TS-1 also has special Si-O-Ti framework bonds due to the uniform distribution of titanium atoms in the framework, which gives it both catalytic oxidation activity and shape-selective catalytic performance.

[0003] With ongoing research, the performance of titanium-silicon molecular sieve catalysts has been continuously improved, leading to their industrialization in numerous fields, particularly cyclohexanone ammonium oxime oxidation and olefin epoxidation. Currently, in industrial applications, the requirements for catalysts vary depending on the reactor type. Fixed-bed catalysts, in particular, need to be molded to the millimeter scale and possess sufficient strength to meet the requirements of fixed-bed packing.

[0004] Currently, common molding methods for titanium-silicon molecular sieves include extrusion molding, tablet molding, and ball forming. Ball forming produces catalyst particles with regularity, low bed pressure drop, and minimal breakage during loading, making it a relatively ideal molding method.

[0005] Regardless of the molding method, a certain amount of binder, such as silica sol, is required for molding. A higher binder ratio results in better strength, but the catalytic performance is affected as the proportion of raw powder decreases. Therefore, developing a ball-forming method with a low binder ratio and high strength is important for industrial applications. Summary of the Invention

[0006] In view of this, the present invention aims to provide a titanium-silicon molecular sieve and a method for preparing the same by spheroidization, in order to solve at least one technical problem in the background art.

[0007] To achieve the above objectives, the technical solution of the present invention is implemented as follows:

[0008] A method for preparing a titanium-silicon molecular sieve and its spheroidization process includes the following steps:

[0009] S1: The slurry of titanium-silicon molecular sieve to be rolled into balls is obtained by spray drying and calcination after crystallization.

[0010] S2: The molecular sieve powder, binder, water and lubricant prepared in step S1 are rolled into wet balls in one step to obtain wet balls;

[0011] S3: The wet spheres prepared in step S2 are mixed with the molecular sieve powder, binder, water and lubricant prepared in step S1 and then rolled to form secondary wet spheres.

[0012] S4: Dry and calcine the secondary molded wet spheres prepared in step S3 to obtain the final rolled sphere titanium-silicon molecular sieve;

[0013] Wherein, the proportion of water in step S3 in the total molecular sieve powder, binder, water and lubricant prepared in step S1 is not less than the proportion of water in step S2 in the total molecular sieve powder, binder, water and lubricant prepared in step S1; and the proportion of lubricant in step S3 in the total molecular sieve powder, binder, water and lubricant prepared in step S1 is not greater than the proportion of lubricant in step S2 in the total molecular sieve powder, binder, water and lubricant prepared in step S1.

[0014] Further, in step S2, the molar ratio of molecular sieve powder, binder, water, and lubricant is 1:(0.01-0.2):(0.01-0.1):(0.05-0.2), and in step S3, the molar ratio of molecular sieve powder, binder, water, and lubricant is 1:(0.01-0.2):(0.05-0.2):(0.01-0.1).

[0015] Furthermore, in step S2, the diameter of the wet bulb formed in one step is 0.3-0.6 mm;

[0016] And / or, the diameter of the secondary formed wet ball in step S3 is 1.5-3 mm.

[0017] Furthermore, in step S1, after crystallization, the solid spherical particles are prepared by spray drying and shaping using a spray drying device, and then calcined to obtain a spherical molecular sieve.

[0018] Furthermore, the spray drying equipment is either a pressure spray dryer or a centrifugal spray dryer;

[0019] And / or, the diameter of the solid spherical particles is 10-200 micrometers; preferably 20-40 micrometers;

[0020] And / or, the temperature during spray drying is 200-500℃;

[0021] And / or, after spray drying, calcination is carried out at a temperature of 400-800℃ for 2-10 hours.

[0022] Furthermore, the lubricant used in steps S2 and S3 is the mother liquor that has not been spray-dried after molecular sieve crystallization.

[0023] Furthermore, the binder in steps S2 and S3 includes silica sol or water glass. Preferably, the binder is silica sol, and preferably, the solid content of the binder is 20%-40%.

[0024] Furthermore, the ball rolling in steps S2 and S3 uses a ball rolling machine;

[0025] And / or, the diameter of the ball rolling machine is 0.5-2m;

[0026] And / or, the rotation speed of the ball rolling machine is 200-3000 rpm.

[0027] Furthermore, after secondary molding, the wet balls do not stick together. After sieving, they are sieved through a 1.5-3mm sieve and then dried and calcined.

[0028] And / or, after secondary molding and screening, the small balls are dried at a temperature of 50-100℃ for 24-72 hours.

[0029] And / or, the firing temperature after secondary molding is 400-800℃, and the firing time is 2-10h.

[0030] Furthermore, the diameter of the titanium-silicon molecular sieve after spheroidizing is 1.5-3 mm, and the strength is 5N-15N / mm.

[0031] Compared with existing technologies, the titanium-silicon molecular sieve and its preparation method by spheroidization described in this invention have the following advantages:

[0032] 1. This application utilizes a secondary ball-forming process to coat the surface of wet balls with molecular sieve powder and binder, forming a denser layered structure. This significantly improves the compressive strength and wear resistance of the balls, reducing the risk of breakage in industrial applications. Simultaneously, the step-by-step forming process combined with the use of lubricant optimizes the uniformity and size control of the balls, preventing cracking or deformation. The balls prepared by this method exhibit high strength and uniform particle size, making them well-suited for applications in olefin epoxidation.

[0033] 2. The spray drying and staged calcination process of this application effectively removes organic template agents and lubricants, improving the specific surface area and accessibility of active sites of the molecular sieve. Secondary molding results in a more uniform distribution of titanium active centers, reducing pore blockage by binders and thus improving catalytic efficiency, making it suitable for demanding oxidation reactions (such as olefin epoxidation).

[0034] 3. The stepwise drying and calcination process in this application avoids the defects caused by direct high-temperature treatment of wet bulbs, resulting in a high yield and good repeatability. This method reduces production costs by balancing binder dosage and mechanical strength, while also meeting the needs of large-scale production, providing a reliable solution for the industrial application of titanium-silicon molecular sieves. Detailed Implementation

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0036] The present invention will now be described in detail with reference to the embodiments.

[0037] The molecular sieves used in the following examples and comparative examples were prepared in accordance with patent ZL201410826401.2.

[0038] Example 1:

[0039] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 10 micrometers by centrifugal spray drying, and then calcined at 400℃ for 10h to obtain a molecular sieve for rolling balls.

[0040] 2) In the ball-forming machine, molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used during ball forming is the mother liquor of molecular sieve crystallization that has not been spray-dried) are sequentially formed in one step to obtain wet balls of approximately 0.3 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming process is 1:0.01:0.01:0.05.

[0041] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used in the ball rolling process is the mother liquor of molecular sieve crystallization that has not been spray-dried) and then subjected to secondary forming to obtain wet balls of about 1.5 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.01:0.05:0.01.

[0042] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 50℃ and the drying time is 24h. The calcination temperature after secondary molding is 400℃ and the calcination time is 2h.

[0043] 5) The diameter of the ball rolling machine used is 2m. The rotation speed of the ball rolling machine is 200rpm.

[0044] Example 2:

[0045] 1) After the prepared titanium-silicon molecular sieve is crystallized, the slurry is prepared into solid spherical particles of 50 micrometers by pressure spray drying, and then calcined at 800℃ for 2 hours to obtain a molecular sieve for rolling.

[0046] 2) In the ball rolling machine, molecular sieve powder, binder (silica sol), water, and lubricant are sequentially formed in one step to obtain wet balls of approximately 0.6 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.2:0.1:0.2.

[0047] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 3mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.2:0.1:0.2.

[0048] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 100℃ and the drying time is 72h. The calcination temperature after secondary molding is 800℃ and the calcination time is 10h.

[0049] 5) The diameter of the ball rolling machine used for ball rolling is 0.5m. The rotation speed of the ball rolling machine is 3000rpm.

[0050] Example 3:

[0051] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 20 micrometers by centrifugal spray drying, and then calcined at 600℃ for 6 hours to obtain a molecular sieve for rolling spheres.

[0052] 2) In the ball rolling machine, molecular sieve powder, binder (silica sol), water, and lubricant are sequentially formed in one step to obtain wet balls of approximately 0.6 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.1:0.05:0.1.

[0053] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 2.5 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.1:0.05:0.1.

[0054] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 80℃ and the drying time is 36h. The calcination temperature after secondary molding is 700℃ and the calcination time is 8h.

[0055] 5) The diameter of the ball rolling machine used for ball rolling is 1m, and the speed of the ball rolling machine is 2000rpm.

[0056] Example 4:

[0057] 1) After the prepared titanium-silicon molecular sieve is crystallized, the slurry is prepared into solid spherical particles of 30 micrometers by pressure spray drying, and then calcined at 550℃ for 4 hours to obtain a molecular sieve for rolling.

[0058] 2) In the ball rolling machine, molecular sieve powder, binder (water glass), water, and lubricant are sequentially formed in one step to obtain wet balls of about 0.6 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.1:0.05:0.1.

[0059] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (water glass), water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 2 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.1:0.05:0.1.

[0060] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 80℃ and the drying time is 24h. The calcination temperature after secondary molding is 80℃ and the calcination time is 6h.

[0061] 5) The diameter of the ball rolling machine used for ball rolling is 2m, and the speed of the ball rolling machine is 2000rpm.

[0062] Example 5:

[0063] 1) After the prepared titanium-silicon molecular sieve is crystallized, the slurry is prepared into solid spherical particles of 40 micrometers by pressure spray drying, and then calcined at 700℃ for 8 hours to obtain a molecular sieve for rolling.

[0064] 2) In the ball rolling machine, molecular sieve powder, binder (silica sol), water, and lubricant are sequentially formed in one step to obtain wet balls of approximately 0.6 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.1:0.05:0.1.

[0065] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 2 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.1:0.05:0.1.

[0066] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 80℃ and the drying time is 24h. The calcination temperature after secondary molding is 80℃ and the calcination time is 6h.

[0067] 5) The diameter of the ball rolling machine used for ball rolling is 2m, and the speed of the ball rolling machine is 3000rpm.

[0068] Example 6:

[0069] 1) After the prepared titanium-silicon molecular sieve is crystallized, the slurry is prepared into solid spherical particles of 20 micrometers by pressure spray drying, and then calcined at 700℃ for 6 hours to obtain a molecular sieve for rolling.

[0070] 2) In the ball rolling machine, molecular sieve powder, binder (silica sol), water, and lubricant are sequentially formed in one step to obtain wet balls of approximately 0.6 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.1:0.05:0.1.

[0071] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 2 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.1:0.05:0.1.

[0072] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 90℃ and the drying time is 12h. The calcination temperature after secondary molding is 700℃ and the calcination time is 6h.

[0073] 5) The diameter of the ball rolling machine used for ball rolling is 2m, and the speed of the ball rolling machine is 2500rpm.

[0074] Comparative Example 1:

[0075] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 10 micrometers by centrifugal spray drying, and then calcined at 400℃ for 10h to obtain a molecular sieve for rolling balls.

[0076] 2) Molecular sieve powder, binder, and water are sequentially formed in a ball-forming machine to obtain wet balls of approximately 0.3 mm in size. The ratio of molecular sieve, binder (converted to pure silica), and water in the one-time forming process is 1:0.01:0.01.

[0077] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder, water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 1.5 mm in size. The ratio of molecular sieve powder, binder, and water used in the secondary forming is 1:0.01:0.05.

[0078] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 50℃ and the drying time is 24h. The calcination temperature after secondary molding is 400℃ and the calcination time is 2h.

[0079] 5) The diameter of the ball rolling machine used for ball rolling is 2m, and the speed of the ball rolling machine is 200rpm.

[0080] Comparative Example 2:

[0081] 1) After the prepared titanium-silicon molecular sieve is crystallized, the slurry is prepared into particles of 100-200 micrometers by pressure spray drying. The particles are broken and incomplete. After calcination at 800℃ for 2 hours, a spherical molecular sieve is obtained.

[0082] 2) Molecular sieve powder, binder, water, and lubricant are sequentially formed in a ball rolling machine to obtain wet balls of approximately 0.6 mm in size. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-time forming process is 1:0.2:0.1:0.2.

[0083] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder, water, and lubricant, and then subjected to secondary forming to obtain wet balls of about 3mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.2:0.1:0.2.

[0084] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 100℃ and the drying time is 72h. The calcination temperature after secondary molding is 800℃ and the calcination time is 10h.

[0085] 5) The diameter of the ball rolling machine used for ball rolling is 0.5m, and the speed of the ball rolling machine is 3000rpm.

[0086] After molding, the catalyst was tested using a strength tester. The specific method referred to the HG T 2782-2011 standard for determining the crushing resistance of fertilizer catalyst particles. The strength of the entire particle was tested and then divided by the diameter, as shown below:

[0087] Comparative Example 3:

[0088] The difference from Example 1 is that only one molding is performed, without a second molding.

[0089] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 10 micrometers by centrifugal spray drying, and then calcined at 400℃ for 10h to obtain a molecular sieve for rolling balls.

[0090] 2) In the ball-forming machine, molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used during ball forming is the mother liquor of molecular sieve crystallization that has not been spray-dried) are sequentially formed in one step to obtain wet balls of about 1.5 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.01:0.01:0.05.

[0091] 3) The shaped wet spheres are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 50℃ and the drying time is 24h. After the second shaping, the calcination temperature is 400℃ and the calcination time is 2h.

[0092] 4) The diameter of the ball rolling machine used is 2m. The rotation speed of the ball rolling machine is 200rpm.

[0093] Comparative Example 4

[0094] The difference from Example 1 is that it involves three molding processes.

[0095] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 10 micrometers by centrifugal spray drying, and then calcined at 400℃ for 10h to obtain a molecular sieve for rolling balls.

[0096] 2) In the ball-forming machine, molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used during ball forming is the mother liquor of molecular sieve crystallization that has not been spray-dried) are sequentially formed in one step to obtain wet balls of approximately 0.3 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming process is 1:0.01:0.01:0.05.

[0097] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used in the ball rolling process is the mother liquor of molecular sieve crystallization that has not been spray-dried) and then subjected to secondary forming to obtain wet balls of about 1.5 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.01:0.05:0.01.

[0098] 4) In the ball rolling machine, the wet balls formed in the second stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used in the ball rolling process is the mother liquor of molecular sieve crystallization that has not been spray-dried) and then subjected to a third stage of forming to obtain wet balls of about 2.5 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the second stage of forming is 1:0.01:0.05:0.01.

[0099] 5) The wet spheres after the third molding process are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 50℃ and the drying time is 24h. After the second molding, the calcination temperature is 400℃ and the calcination time is 2h.

[0100] 6) The diameter of the ball rolling machine used is 2m. The rotation speed of the ball rolling machine is 200rpm.

[0101] Comparative Example 5:

[0102] The difference from Example 1 is that the proportion of water in the primary molding is greater than the proportion of water in the secondary molding.

[0103] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 10 micrometers by centrifugal spray drying, and then calcined at 400℃ for 10h to obtain a molecular sieve for rolling balls.

[0104] 2) In the ball-forming machine, molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used during ball forming is the mother liquor of molecular sieve crystallization that has not been spray-dried) are sequentially formed in one step to obtain wet balls of approximately 0.3 mm in size. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming process is 1:0.01:0.05:0.05.

[0105] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used in the ball rolling process is the mother liquor of molecular sieve crystallization that has not been spray-dried) and then subjected to secondary forming to obtain wet balls of about 1.5 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.01:0.01:0.01.

[0106] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 50℃ and the drying time is 24h. The calcination temperature after secondary molding is 400℃ and the calcination time is 2h.

[0107] 5) The diameter of the ball rolling machine used is 2m. The rotation speed of the ball rolling machine is 200rpm.

[0108] Comparative Example 6:

[0109] The difference from Example 1 is that the proportion of lubricant in the primary molding is less than the proportion of lubricant in the secondary molding.

[0110] 1) After crystallizing the prepared titanium-silicon molecular sieve slurry, it was prepared into solid spherical particles of 10 micrometers by centrifugal spray drying, and then calcined at 400℃ for 10h to obtain a molecular sieve for rolling balls.

[0111] 2) In the ball rolling machine, molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used during ball rolling is the mother liquor of molecular sieve crystallization that has not been spray-dried) are sequentially formed in one step to obtain wet balls of about 0.3 mm. The ratio of molecular sieve, binder (converted to pure silica), water, and lubricant in the one-step forming is 1:0.01:0.01:0.01.

[0112] 3) In the ball rolling machine, the wet balls formed in the first stage are mixed with molecular sieve powder, binder (silica sol), water, and lubricant (the lubricant used in the ball rolling process is the mother liquor of molecular sieve crystallization that has not been spray-dried) and then subjected to secondary forming to obtain wet balls of about 1.5 mm in size. The ratio of molecular sieve powder, binder, water, and lubricant used in the secondary forming is 1:0.01:0.05:0.05.

[0113] 4) The wet spheres after secondary molding are dried and calcined to obtain the final spheroidized titanium-silicon molecular sieve. The drying temperature is 50℃ and the drying time is 24h. The calcination temperature after secondary molding is 400℃ and the calcination time is 2h.

[0114] 5) The diameter of the ball rolling machine used is 2m. The rotation speed of the ball rolling machine is 200rpm.

[0115] Table 1. Test results of Examples 1-6 and Comparative Examples 1 and 2

[0116]

[0117]

[0118] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing titanium-silicon molecular sieves by spherical molding, characterized in that: The process includes the following steps: S1: After crystallization, the slurry of the titanium-silicon molecular sieve to be ball-forming is spray-dried and calcined to obtain molecular sieve powder for ball-forming; S2: The molecular sieve powder, binder, water, and lubricant prepared in step S1 are ball-formed in one step to obtain a one-time formed wet ball; S3: The one-time formed wet ball prepared in step S2 is mixed with the molecular sieve powder, binder, water, and lubricant prepared in step S1 and then ball-formed in a second step to obtain a two-time formed wet ball; S4: The two-time formed wet ball prepared in step S3 is dried and calcined to obtain the final ball-forming product. The titanium-silicon molecular sieve; wherein, in step S3, the proportion of water in the total molecular sieve powder, binder, water, and lubricant prepared in step S1 is not less than the proportion of water in step S2 in the total molecular sieve powder, binder, water, and lubricant prepared in step S1; and the proportion of lubricant in step S3 in the total molecular sieve powder, binder, water, and lubricant prepared in step S1 is not greater than the proportion of lubricant in step S2 in the total molecular sieve powder, binder, water, and lubricant prepared in step S1. In step S1, after crystallization, the solid spherical particles are prepared by drying and shaping using a spray drying device. The spray drying equipment is either pressure spray drying or centrifugal spray drying; the diameter of the solid spherical particles is 20-40 micrometers.

2. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 1, characterized in that: In step S2, the ratio of molecular sieve powder, binder, water, and lubricant is 1:(0.01-0.2):(0.01-0.1):(0.05-0.2), and in step S3, the ratio of molecular sieve powder, binder, water, and lubricant is 1:(0.01-0.2):(0.05-0.2):(0.01-0.1).

3. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 1, characterized in that: In step S2, the diameter of the wet bulb formed in the first step is 0.3-0.6 mm; and / or, in step S3, the diameter of the wet bulb formed in the second step is 1.5-3 mm.

4. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 1, characterized in that: The spray drying temperature is 200-500℃; and / or the calcination temperature is 400-800℃, and the calcination time is 2-10h.

5. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 1, characterized in that: The lubricant used in steps S2 and S3 is the mother liquor that was not spray-dried after molecular sieve crystallization.

6. The method for preparing a titanium-silicon molecular sieve by spherical forming according to claim 1, characterized in that: The binder in steps S2 and S3 includes silica sol or water glass.

7. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 6, characterized in that: The binder is silica sol.

8. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 6, characterized in that: The solid content of the adhesive is 20%-40%.

9. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 1, characterized in that: The ball rolling in steps S2 and S3 uses a ball rolling machine; and / or the diameter of the ball rolling machine is 0.5-2m; and / or the rotation speed of the ball rolling machine is 200-3000rpm.

10. The method for preparing a titanium-silicon molecular sieve by spherical molding according to claim 1, characterized in that: The secondary molding wet bulb drying temperature is 50-100℃, and the drying time is 24-72h; and / or, the calcination temperature after secondary molding is 400-800℃, and the calcination time is 2-10h.

11. The spheroidized titanium-silicon molecular sieve prepared by the spheroidizing method according to any one of claims 1-10 is characterized in that: The diameter of the titanium-silicon molecular sieve after spheroidization is 1.5-3 mm, and the strength is 10.8-15 N / mm.

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