Molecular sieve product forming pretreatment method

Abstract

The invention relates to the technical field of molecular sieves, in particular to a forming pretreatment method, a molecular sieve product and application of the molecular sieve product. The invention relates to a forming pretreatment method, which comprises the following steps: pretreating a mixed material containing molecular sieve raw powder and a peptizing agent to obtain a precursor; wherein the pretreatment is carried out in high-speed mixing equipment, and the linear speed difference between a rotor and an inner cylinder is controlled to be greater than or equal to 5m / s. According to the method, the homogeneous and dense precursor is obtained by controlling the linear speed difference, and then the molecular sieve product which is relatively good and stable in crushing strength is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of molecular sieves, and particularly relates to a method for pre-treatment before forming, a molecular sieve product and its application. Background Art

[0002] Before the molecular sieve is extruded and formed, the kneading method is often used to knead and compact the materials to ensure the subsequent forming quality. The prior art generally adds the materials into a kneading machine first, mixes them, adds water, and performs differential shearing through a pair of cooperating and rotating paddle blades for pre-treatment, and then sends them to an extruding machine for forming. Since the linear speed of kneading is generally 0.1 m / s, which is relatively slow, local over-wetting is likely to occur after adding water, forming large chunks, and the moisture often cannot be fully and evenly incorporated into the interior of the materials, and the situation of insufficient kneading often occurs, resulting in fluctuations in the quality of the extruded strips. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems such as insufficient pre-treatment of the molecular sieve product in the existing methods, resulting in large fluctuations in product quality, and to provide a method for pre-treatment before forming, a molecular sieve product and its application. By controlling the linear speed difference, a homogeneous and dense precursor is obtained, and then a molecular sieve product with good and stable crushing strength is obtained.

[0004] To achieve the above purpose, the first aspect of the present invention provides a method for pre-treatment before forming, the method comprising: performing pre-treatment on a mixed material containing molecular sieve raw powder and peptizing agent to obtain a precursor; wherein, the pre-treatment is carried out in a high-speed mixing device, and the linear speed difference between the rotor and the inner cylinder is controlled to be ≥ 5 m / s.

[0005] In the present invention, unless otherwise specified, the high-speed mixing device is equipped with a rotor and an inner cylinder, and the rotor and the inner cylinder have different linear speeds; controlling the linear speed difference between the rotor and the inner cylinder to be ≥ 5 m / s means that the difference between the linear speed of the rotor and the linear speed of the inner cylinder is ≥ 5 m / s.

[0006] Preferably, the method comprises the following steps:

[0007] (1) Dry-mix the molecular sieve raw powder, binder and lubricant to obtain a dry powder;

[0008] (2) Mix the dry powder and the peptizing agent, and perform the pre-treatment on the obtained mixed material.

[0009] The second aspect of the present invention provides a molecular sieve product, which is obtained by successively forming, drying and calcining the precursor prepared by the method provided in the first aspect.

[0010] The third aspect of the present invention provides an application of the molecular sieve product provided in the second aspect in a catalyst and an adsorbent.

[0011] Through the above technical solution, the method provided by the present invention pre-treats the mixed material in a high-speed mixing device and regulates the linear speed difference between the rotor and the inner cylinder within a specific range, so that the molecular sieve raw powder and the peptizing agent in the mixed material are fully mixed to obtain a homogeneous and dense precursor; this method avoids the defects such as insufficient kneading and fluctuating extrusion quality in the prior art, and the prepared product has high crushing strength and quality stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a countercurrent schematic diagram of pre-treatment before forming provided by the present invention;

[0013] Figure 2 is a cross-flow schematic diagram of another pre-treatment before forming provided by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0014] In the ranges disclosed herein, the endpoints and any values are not limited to the exact ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, between the endpoint values of each range, between the endpoint values of each range and individual point values, and between individual point values, they can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed herein.

[0015] The first aspect of the present invention provides a method for pre-treatment before forming, the method comprising: pre-treating a mixed material containing molecular sieve raw powder and peptizing agent to obtain a precursor;

[0016] Wherein, the pre-treatment is carried out in a high-speed mixing device, and the linear speed difference between the rotor and the inner cylinder is controlled to be ≥5 m / s.

[0017] The inventors of the present invention have found through research that: pre-treating a mixed material containing molecular sieve raw powder and peptizing agent in a high-speed mixing device, by regulating the linear speed difference between the rotor and the inner cylinder, during the pre-treatment process, the rotor and the inner cylinder each drive a stream of material to move relatively in a countercurrent or cross-flow manner, and through dispersion, mixing, adhesion, and compaction, a homogeneous and dense precursor is achieved; in particular, the greater the linear speed difference between the rotor and the inner cylinder, the more intense the relative movement of the material, and the more sufficient the treatment effect.

[0018] In the present invention, without special circumstances, in addition to the molecular sieve raw powder and the peptizing agent, the mixed material also contains a binder, a lubricant, etc.

[0019] In some embodiments of the present invention, the linear velocity difference between the rotor and the inner cylinder is ≥5 m / s. For example, 5 m / s, 8 m / s, 10 m / s, 12 m / s, 15 m / s, 18 m / s, 20 m / s, 25 m / s, 23 m / s, 25 m / s, 30 m / s, and any value within the range composed of any two numerical values. Preferably, it is ≥10 m / s, more preferably ≥18 m / s, and even more preferably ≥25 m / s.

[0020] In some embodiments of the present invention, preferably, the linear velocity of the rotor is 9 m / s - 27.5 m / s. For example, 9 m / s, 10 m / s, 15 m / s, 17 m / s, 20 m / s, 25 m / s, and any value within the range composed of any two numerical values. Preferably, it is 17 m / s - 27.5 m / s. In the present invention, the linear velocity of the rotor is adjustable. In the present invention, the linear velocity of the rotor = (πRv) / 60, where R is the diameter of the rotor, in m; v is the rotational speed of the rotor, in r / min.

[0021] In some embodiments of the present invention, preferably, the linear velocity of the inner cylinder is 0.2 m / s - 1.6 m / s. In the present invention, the linear velocity of the inner cylinder is adjustable. In the present invention, the linear velocity of the inner cylinder = (πR’v’) / 60, where R’ is the inner diameter of the inner cylinder, in m; v’ is the rotational speed of the inner cylinder, in r / min.

[0022] In some embodiments of the present invention, preferably, the pre-treatment method is selected from countercurrent or crossflow, and preferably countercurrent. Compared with the crossflow pre-treatment method, when using the countercurrent pre-treatment method, the linear velocity difference is greater and the effect is better.

[0023] In a specific embodiment of the present invention, as Figure 1 shown, the "plus" in the figure represents the rotor. When using the countercurrent pre-treatment method, the linear velocity difference between the rotor and the inner cylinder is the linear velocity of the rotor + the linear velocity of the inner cylinder; as Figure 2 shown, the "plus" in the figure represents the rotor. When using the crossflow pre-treatment method, the linear velocity difference between the rotor and the inner cylinder is the linear velocity of the rotor - the linear velocity of the inner cylinder.

[0024] In some embodiments of the present invention, preferably, the method includes the following steps:

[0025] (1) Dry-mix the molecular sieve raw powder, binder, and lubricant to obtain a dry powder;

[0026] (2) Mix the dry powder and peptizing agent, and subject the obtained mixed material to the pre-treatment.

[0027] In the present invention, the dry mixing is intended to uniformly mix the molecular sieve raw powder, the binder, and the lubricant to obtain a uniformly mixed dry powder. Preferably, in step (1), the dry mixing is carried out in a high-speed mixing device; the conditions for the dry mixing include: the linear velocity difference is 3 m / s - 8 m / s, for example, 3 m / s, 5 m / s, 5.5 m / s, 6 m / s, 8 m / s, and any value within the range composed of any two of these values, preferably 5 m / s - 6 m / s; the time is 1 - 10 min, preferably 1 - 5 min. Meeting the above conditions, a uniformly mixed dry powder can be obtained on the premise of reducing dust emission.

[0028] In some embodiments of the present invention, preferably, the conditions for the dry mixing further include: controlling the linear velocity of the rotor to be 2 m / s - 5 m / s; controlling the linear velocity of the inner cylinder to be 0.5 m / s - 1.6 m / s.

[0029] In the present invention, without special instructions, the dry mixing is carried out in a high-speed mixing device, and the dry mixing method is selected from countercurrent or crossflow.

[0030] In some embodiments of the present invention, preferably, in step (1), the weight ratio of the molecular sieve raw powder to the binder based on dry basis is 60 - 95:40 - 5, for example, 60:40, 70:30, 80:20, 90:10, 95:5, and any value within the range composed of any two of these values.

[0031] In the present invention, there is a relatively wide selection range for the type of the binder. Preferably, the binder is selected from at least one of pseudo-boehmite, γ-aluminum oxide, and clay.

[0032] In some embodiments of the present invention, preferably, based on the total weight of the molecular sieve raw powder and the binder, the content of the lubricant is 1 - 10 wt%, for example, 1 wt%, 2 wt%, 3 wt%, 5 wt%, 8 wt%, 10 wt%, and any value within the range composed of any two of these values, preferably 1 - 5 wt%.

[0033] In some embodiments of the present invention, preferably, the lubricant is selected from at least one of starch, methyl cellulose, sesbania powder, and graphite.

[0034] In the present invention, the dosage of the peptizing agent depends not only on the weight of the dry powder but also on the type of the peptizing agent.

[0035] In some embodiments of the present invention, preferably, the peptizing agent is selected from inorganic acids and / or organic acids, preferably selected from at least one of nitric acid, hydrochloric acid, sulfuric acid, and citric acid.

[0036] In some embodiments of the present invention, preferably, the peptizing agent exists in the form of an aqueous solution, and the concentration of the peptizing agent aqueous solution is 0.5 - 20 wt%, for example, 0.5 wt%, 1 wt%, 2 wt%, 5 wt%, 8 wt%, 10 wt%, 15 wt%, 20 wt%, and any value within the range composed of any two numerical values, preferably 1 - 10 wt%.

[0037] In some embodiments of the present invention, preferably, the time of the pretreatment is 20 - 60 min, preferably 25 - 35 min. When the time of the pretreatment is too short, the treatment is insufficient; when the time of the pretreatment is too long, the improvement effect is not obvious, but instead affects the production efficiency.

[0038] The second aspect of the present invention provides a molecular sieve product, which is prepared by successively subjecting the precursor prepared by the method provided in the first aspect to shaping, drying, and calcination.

[0039] In the present invention, there is a wide range of choices for the shaping method. Preferably, the shaping method is selected from extrusion molding and rolling molding. The extrusion molding is carried out in an extruder; the rolling molding is carried out in a rolling ball machine.

[0040] In some embodiments of the present invention, preferably, the drying conditions include: the temperature is 80 - 150 °C, preferably 100 - 130 °C; the time is 0.1 - 10 h, preferably 0.5 - 5 h.

[0041] In some embodiments of the present invention, preferably, the calcination conditions include: the temperature is 400 - 600 °C, preferably 500 - 600 °C; the time is 0.1 - 10 h, preferably 0.5 - 3 h.

[0042] In some embodiments of the present invention, preferably, the variance of the crushing strength of the molecular sieve product ≤ 30%, preferably ≤ 10%, for example, 0.2%, 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, and any value within the range composed of any two numerical values. Meeting the above parameters indicates that the crushing strength of the molecular sieve product is stable and has small fluctuations.

[0043] In some embodiments of the present invention, preferably, the crushing strength of the molecular sieve product ≥ 100 N / cm, for example, 110 N / cm, 112 N / cm, 115 N / cm, 118 N / cm, 120 N / cm, and any value within the range composed of any two numerical values. In the present invention, the crushing strength is tested by a DL2 particle strength tester (produced by Dalian Penghui Science and Technology Development Co., Ltd.).

[0044] In some embodiments of the present invention, a preparation method of a molecular sieve product includes:

[0045] (1) In a high-speed mixing device, the molecular sieve raw powder, binder, and lubricant are dry-mixed to obtain a dry powder;

[0046] (2) In a high-speed mixing device, the dry powder and peptizing agent are mixed, and the obtained mixed material is pretreated to obtain a precursor;

[0047] (3) The precursor is successively molded, dried, and calcined to obtain the molecular sieve product.

[0048] The third aspect of the present invention provides an application of the molecular sieve product provided in the second aspect in a catalyst and an adsorbent.

[0049] According to a particularly preferred embodiment of the present invention, a preparation method of a molecular sieve product includes:

[0050] (1) In a high-speed mixing device, the molecular sieve raw powder, binder, and lubricant are dry-mixed to obtain a dry powder; the conditions for the dry mixing include: controlling the linear velocity difference between the rotor and the inner cylinder to be 5 m / s - 6 m / s; the time is 1 - 5 min; controlling the linear velocity of the rotor to be 2 m / s - 5 m / s; controlling the linear velocity of the inner cylinder to be 0.5 m / s - 1.6 m / s;

[0051] (2) In a high-speed mixing device, the dry powder and peptizing agent are mixed, and the obtained mixed material is pretreated to obtain a precursor; the conditions for the pretreatment include: the time is 25 - 35 min, controlling the linear velocity difference between the rotor and the inner cylinder to be ≥25 m / s, the linear velocity of the rotor is 17 m / s - 27.5 m / s, and the linear velocity of the inner cylinder is 0.2 m / s - 1.6 m / s;

[0052] (3) The precursor is successively molded, dried, and calcined to obtain a molecular sieve product;

[0053] Among them, the variance of the crushing strength of the molecular sieve product ≤10%; the crushing strength of the molecular sieve product ≥100 N / cm.

[0054] The present invention will be described in detail below through examples.

[0055] Example 1

[0056] (1) In a high-speed mixing device, a high-silica (silicon-aluminum molar ratio of 120) molecular sieve raw powder, binder (pseudoboehmite), and lubricant (spergon powder) are countercurrently dry-mixed to obtain a dry powder;

[0057] Among them, the weight ratio of the above-mentioned molecular sieve raw powder to the binder based on dry basis is 70:30; based on the total weight of the above-mentioned molecular sieve raw powder and binder, the content of the above-mentioned lubricant is 2 wt%;

[0058] The conditions for the above dry mixing include: the linear velocity difference is 5 m / s; the time is 2 min, the linear velocity of the rotor is 4 m / s, and the linear velocity of the inner cylinder is 1 m / s;

[0059] (2) To the above dry powder, a peptizing agent (aqueous nitric acid solution with a concentration of 6 wt%) is added, and countercurrent mixing is carried out, controlling the linear velocity difference to be 29 m / s, the time to be 30 min, the linear velocity of the rotor to be 27.5 m / s, and the linear velocity of the inner cylinder to be 1.5 m / s, to obtain a precursor;

[0060] (3) The above precursor is transferred to an extruder, and small strips with a diameter of 2 mm are extruded, dried at 120 °C for 2 h to obtain broken strips with a length of 3 - 8 mm, and calcined at 550 °C for 2 h.

[0061] The above operations are repeated 3 times to obtain molecular sieve samples S1-1, S1-2, and S1-3 respectively, and the crushing strength tests are carried out respectively. The test results are shown in Table 1.

[0062] Example 2

[0063] According to the method of Example 1, the difference is that

[0064] In step (2), the linear velocity of the rotor is adjusted to 20 m / s, the linear velocity of the inner cylinder is 0.8 m / s, and cross-flow mixing is carried out to make the linear velocity difference 19.2 m / s;

[0065] Under the same other conditions, the above operations are repeated 3 times to obtain molecular sieve samples S2-1, S2-2, and S2-3 respectively, and the crushing strength tests are carried out respectively.

[0066] Example 3

[0067] According to the method of Example 1, the difference is that

[0068] In step (2), the linear velocity of the rotor is adjusted to 15 m / s, and countercurrent mixing is adopted to make the linear velocity difference 16.5 m / s;

[0069] Under the same other conditions, the above operations are repeated 3 times to obtain molecular sieve samples S3-1, S3-2, and S3-3 respectively, and the crushing strength tests are carried out respectively. The test results are shown in Table 1.

[0070] Example 4

[0071] According to the method of Example 1, the difference is that

[0072] In step (2), the linear velocity of the rotor is adjusted to 10 m / s, and countercurrent mixing is adopted to make the linear velocity difference 11.5 m / s;

[0073] Under the same other conditions, repeat the above operations 3 times to obtain molecular sieve samples S4-1, S4-2, and S4-3 respectively, and conduct crushing strength tests on them. The test results are shown in Table 1.

[0074] Example 5

[0075] According to the method of Example 1, the difference is that

[0076] In step (2), adjust the linear velocity of the rotor to 4 m / s and adopt a countercurrent mixing method to make the linear velocity difference 5.5 m / s;

[0077] Under the same other conditions, repeat the above operations 3 times to obtain molecular sieve samples S5-1, S5-2, and S5-3 respectively, and conduct crushing strength tests on them. The test results are shown in Table 1.

[0078] Example 6

[0079] According to the method of Example 1, the difference is that

[0080] In step (2), adjust the time of the pretreatment to 40 min;

[0081] Under the same other conditions, repeat the above operations 3 times to obtain molecular sieve samples S6-1, S6-2, and S6-3 respectively, and conduct crushing strength tests on them. The test results are shown in Table 1.

[0082] Example 7

[0083] According to the method of Example 1, the difference is that

[0084] In step (2), adjust the time of the pretreatment to 15 min;

[0085] Under the same other conditions, repeat the above operations 3 times to obtain molecular sieve samples S7-1, S7-2, and S7-3 respectively, and conduct crushing strength tests on them. The test results are shown in Table 1.

[0086] Comparative Example 1

[0087] According to the method of Example 1, the difference is that

[0088] In step (1), the dry mixing is carried out in a kneader, and the blade linear velocity is 0.1 m / s;

[0089] In step (2), the mixing is carried out in a kneader, and the blade linear velocity is 0.1 m / s;

[0090] Under the same other conditions, repeat the above operations 3 times to obtain molecular sieve samples DS1-1, DS1-2, and DS1-3 respectively, and conduct crushing strength tests on them. The test results are shown in Table 1.

[0091] Comparative Example 2

[0092] According to the method of Example 1, except that

[0093] In step (2), the linear velocity of the rotor is adjusted to 2 m / s, and the countercurrent mixing method is adopted to make the linear velocity difference 3.5 m / s;

[0094] Under the same other conditions, the above operations are repeated 3 times to obtain molecular sieve samples DS2-1, DS2-2 and DS2-3 respectively, and the crushing strength tests are carried out respectively. The test results are shown in Table 1.

[0095] Table 1

[0096]

[0097]

[0098] Note: * - The operations of the examples and comparative examples are repeated 3 times, and the obtained molecular sieve samples are subjected to crushing strength tests respectively.

[0099] It can be seen from the results in Table 1 that compared with Comparative Example 1-2, by using the method provided by the present invention, a homogeneous and dense precursor can be obtained; at the same time, the prepared molecular sieve product has a high crushing strength and stable quality.

[0100] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, including any other suitable combination of each technical feature. These simple modifications and combinations should also be regarded as the content disclosed by the present invention and fall within the protection scope of the present invention.

Claims

1. A method for pre-treatment before forming, characterized in that, the method includes: performing pre-treatment on a mixed material containing molecular sieve raw powder and peptizing agent to obtain a precursor; wherein, the pre-treatment is performed in a high-speed mixing device, and the linear velocity difference between the rotor and the inner cylinder is controlled to be ≥5 m / s.

2. The method according to claim 1, wherein, the linear velocity difference between the rotor and the inner cylinder is controlled to be ≥10 m / s, preferably ≥18 m / s, more preferably ≥25 m / s; and / or, the linear velocity of the rotor is 9 m / s - 27.5 m / s, preferably 17 m / s - 27.5 m / s; and / or, the linear velocity of the inner cylinder is 0.2 m / s - 1.6 m / s; and / or, the pre-treatment method is selected from countercurrent or crossflow.

3. The method according to claim 1 or 2, wherein, the method includes the following steps: (1) Dry-mixing the molecular sieve raw powder, binder and lubricant to obtain a dry powder; (2) Mixing the dry powder and peptizing agent, and performing the pre-treatment on the obtained mixed material.

4. The method according to claim 3, wherein, in step (1), the dry-mixing is performed in a high-speed mixing device; the conditions for dry-mixing include: the linear velocity difference is 3 m / s - 8 m / s, preferably 5 m / s - 6 m / s; the time is 1 - 10 min, preferably 1 - 5 min; and / or, the conditions for dry-mixing further include: controlling the linear velocity of the rotor to be 2 m / s - 5 m / s; controlling the linear velocity of the inner cylinder to be 0.5 m / s - 1.6 m / s.

5. The method according to claim 3 or 4, wherein, in step (1), the weight ratio of the molecular sieve raw powder to the binder based on dry basis is 60 - 95:40 - 5; and / or, the binder is selected from at least one of pseudoboehmite, γ-aluminum oxide and clay; and / or, based on the total weight of the molecular sieve raw powder and binder, the content of the lubricant is 1 - 10 wt%, preferably 1 - 5 wt%; and / or, the lubricant is selected from at least one of starch, methyl cellulose, sesbania powder and graphite.

6. The method according to any one of claims 3 - 5, wherein, in step (2), the time for the pre-treatment is 20 - 60 min, preferably 25 - 35 min; and / or, the peptizing agent exists in the form of an aqueous solution, and the concentration of the peptizing agent aqueous solution is 0.5 - 20 wt%, preferably 1 - 10 wt%.

7. A molecular sieve product, characterized in that, the molecular sieve product is prepared from the precursor obtained by the method according to any one of claims 1 - 6, successively through forming, drying and calcining.

8. The molecular sieve product according to claim 7, wherein, the forming method is selected from extrusion forming, rolling forming; and / or, the drying conditions include: temperature is 80 - 150 °C, preferably 100 - 130 °C; time is 0.1 - 10 h, preferably 0.5 - 5 h; and / or, the calcining conditions include: temperature is 400 - 600 °C, preferably 500 - 600 °C; time is 0.1 - 10 h, preferably 0.5 - 3 h.

9. The molecular sieve product according to claim 7 or 8, wherein, the variance of the crushing strength of the molecular sieve product ≤ 30%, preferably ≤ 10%; and / or, the crushing strength of the molecular sieve product ≥ 100 N / cm.

10. Use of the molecular sieve product according to any one of claims 7-9 in a catalyst or an adsorbent.

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