Uzm-8 molecular sieve, method for preparing the same, catalyst containing the same and use thereof

Abstract

The present disclosure relates to a kind of UZM-8 molecular sieve and its preparation method, catalyst and application containing UZM-8 molecular sieve, the method includes: the raw material mixture containing silicon aluminum source, first template agent, second template agent and water is carried out hydrothermal crystallization reaction and recovers product;Wherein, the first template agent is at least one selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide, the second template agent is dimethyl diethyl ammonium hydroxide.Compared with the UZM-8 molecular sieve synthesized by traditional hydrothermal method, the UZM-8 molecular sieve with high crystallinity, high specific surface area and pore volume can be synthesized in the present disclosure, while the synthesis cost of molecular sieve is significantly reduced.

Description

Technical Field

[0001] This disclosure relates to a UZM-8 molecular sieve and its preparation method, as well as catalysts containing UZM-8 molecular sieves and their applications. Background Technology

[0002] Ethylbenzene, an important chemical raw material, is mainly used for dehydrogenation to produce styrene, and subsequently for the production of styrene-based resins such as polystyrene (PS), acrylonitrile-butadiene-styrene (ABS), styrene-acrylonitrile (SAN), and styrene-butadiene rubber (SBR). Currently, the main production processes for ethylbenzene include the AlCl3 method, the Alkar gas-phase method, the catalytic distillation process using molecular sieves, and the molecular sieve liquid-phase method. However, the first two methods have been gradually phased out due to their drawbacks such as environmental pollution, equipment corrosion, and high energy consumption. The molecular sieve liquid-phase method was developed to address the shortcomings of the gas-phase method. Currently, the catalysts used in the industrial-scale synthesis of ethylbenzene in the liquid phase include Y, Beta, and MCM-22 molecular sieve catalysts.

[0003] UZM-8 molecular sieves possess the MWW topology and have been found to be suitable for the liquid-phase alkylation reaction of ethylene and benzene. However, the synthesis cost of UZM-8 molecular sieves in related technologies is high, the crystallinity of the product is relatively low, and there is still room for improvement in its catalytic activity and ethylbenzene selectivity for the liquid-phase alkylation reaction of ethylene and benzene. Summary of the Invention

[0004] The purpose of this disclosure is to provide a UZM-8 molecular sieve and its preparation method, a catalyst containing UZM-8 molecular sieve and its applications, so as to reduce the synthesis cost and improve the catalytic activity of UZM-8 molecular sieve products.

[0005] To achieve the above objectives, the first aspect of this disclosure provides a method for preparing UZM-8 molecular sieve, the method comprising:

[0006] A mixture of raw materials containing a silicon-aluminum source, a first template agent, a second template agent, and water is subjected to a hydrothermal crystallization reaction, and the product is recovered.

[0007] The first template agent is at least one selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, and the second template agent is dimethyldiethylammonium hydroxide.

[0008] Optionally, the molar ratio of the first template agent to the second template agent is (0.1-1):1, preferably (0.25-0.67):1.

[0009] Optionally, the first template agent is tetramethylammonium hydroxide and tetraethylammonium hydroxide, wherein the molar ratio of the tetramethylammonium hydroxide to the tetraethylammonium hydroxide is (0.2-2):1.

[0010] Optionally, the molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 10-100, H2O / SiO2 = 8-50, R / SiO2 = 0.05-1.5;

[0011] Preferably, the molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 15-40, H2O / SiO2 = 9-40, and R / SiO2 = 0.1-0.9;

[0012] More preferably, the molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 15-30, H2O / SiO2 = 10-20, R / SiO2 = 0.3-0.5;

[0013] Wherein, R represents the total number of moles of the first template agent and the second template agent.

[0014] Optionally, the raw material mixture further contains an alkali source, and the molar ratio of the raw material mixture includes: B / SiO2 = 0.05 to 0.5, where B represents the molar number of the alkali source.

[0015] Optionally, the alkali source is at least one selected from sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

[0016] Optionally, the silicon-aluminum source is silicon-aluminum paste.

[0017] Optionally, the conditions for the hydrothermal crystallization reaction include: a temperature of 130–180°C and a time of 5–21 days;

[0018] Preferably, the conditions for the hydrothermal crystallization reaction include: a temperature of 130–160°C and a time of 7–17 days;

[0019] More preferably, the conditions for the hydrothermal crystallization reaction include: a temperature of 150–160°C and a time of 10–17 days.

[0020] A second aspect of this disclosure provides a UZM-8 molecular sieve prepared by the method described in the first aspect of this disclosure.

[0021] In a third aspect, this disclosure provides a catalyst comprising a support and the UZM-8 molecular sieve described in the second aspect of this disclosure, wherein the content of the UZM-8 molecular sieve is 30-90% by weight, preferably 70-80% by weight, based on the dry weight of the catalyst.

[0022] A fourth aspect of this disclosure provides the application of the catalyst described in the third aspect of this disclosure in the liquid-phase alkylation reaction of ethylene and benzene, the application comprising: reacting ethylene and benzene in the presence of the catalyst at a reaction temperature of 180–260°C, a reaction pressure of 2.0–4.0 MPa, and a benzene weight hourly space velocity of 1–5 h⁻¹. -1 The alkylation reaction was carried out under the condition that the molar ratio of benzene to ethylene was (2-12):1.

[0023] The advantages of this disclosure through the above technical solution are as follows:

[0024] (1) Compared with the UZM-8 molecular sieve synthesized by the traditional hydrothermal method, the present invention uses a composite template agent to synthesize UZM-8 molecular sieve with high crystallinity, high specific surface area and pore volume, while significantly reducing the synthesis cost of molecular sieve.

[0025] (2) Compared with catalysts prepared by UZM-8 molecular sieves synthesized by other methods, the UZM-8 molecular sieve catalyst disclosed herein has better catalytic activity in the liquid-phase alkylation reaction of ethylene and benzene, which is beneficial to improving the conversion rate of ethylene and / or the selectivity of the target product ethylbenzene, and has good application prospects.

[0026] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0027] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0028] Figure 1 This is the XRD pattern of the UZM-8 molecular sieve prepared in Example 1.

[0029] Figure 2 This is a SEM image of the UZM-8 molecular sieve prepared in Example 1. Detailed Implementation

[0030] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0031] In a first aspect, this disclosure provides a method for preparing UZM-8 molecular sieve, the method comprising:

[0032] A mixture of raw materials containing a silicon-aluminum source, a first template agent, a second template agent, and water is subjected to a hydrothermal crystallization reaction, and the product is recovered.

[0033] The first template agent is at least one selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, and the second template agent is dimethyldiethylammonium hydroxide.

[0034] This disclosure uses a first template agent and a second template agent as a composite template agent, which can synthesize high-quality UZM-8 molecular sieves under hydrothermal crystallization conditions. The first template agent is selected from inexpensive quaternary ammonium base template agents, which significantly reduces the synthesis cost.

[0035] According to this disclosure, the molar ratio of the first template agent to the second template agent can be (0.1 to 1):1. To further reduce the synthesis cost and improve the quality of the molecular sieve product, the molar ratio of the first template agent to the second template agent is preferably (0.25 to 0.67):1.

[0036] The first template agent is tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, or tetrabutylammonium hydroxide, or a combination of two or three thereof. In a preferred embodiment of this disclosure, the first template agent is tetramethylammonium hydroxide and tetraethylammonium hydroxide, and the molar ratio of tetramethylammonium hydroxide to tetraethylammonium hydroxide can be (0.2-2):1. Using tetramethylammonium hydroxide and tetraethylammonium hydroxide in the above ratio as the first template agent combined with the second template agent is beneficial to further reduce synthesis costs and improve the quality of molecular sieve products.

[0037] According to this disclosure, the molar ratio of the raw material mixture may include: SiO2 / Al2O3 = 10-100, H2O / SiO2 = 8-50, R / SiO2 = 0.05-1.5; preferably, the molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 15-40, H2O / SiO2 = 9-40, R / SiO2 = 0.1-0.9; more preferably, the molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 15-30, H2O / SiO2 = 10-20, R / SiO2 = 0.3-0.5; wherein, R represents the total number of moles of the first template agent and the second template agent.

[0038] In one specific embodiment of this disclosure, the raw material mixture may further contain an alkali source, and the molar ratio of the raw material mixture further includes: B / SiO2 = 0.05–0.5, preferably B / SiO2 = 0.10–0.3, wherein B represents the molar number of the alkali source. When the raw material mixture contains an alkali source, crystallization can be further promoted and the crystallization reaction time shortened. The alkali source can be an inorganic alkali. Further, the alkali source can be at least one selected from sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide, preferably sodium hydroxide.

[0039] According to this disclosure, the silicon-aluminum source is a substance that can provide silicon and aluminum. In a preferred embodiment, the silicon-aluminum source is a silicon-aluminum adhesive. The silicon-aluminum molar ratio of the silicon-aluminum adhesive can be adjusted within a wide range; for example, the SiO2 / Al2O3 molar ratio of the silicon-aluminum adhesive is not less than 10. The silicon-aluminum adhesive can be a sodium-containing silicon-aluminum adhesive or a sodium-free silicon-aluminum adhesive, preferably a sodium-free silicon-aluminum adhesive. The silicon-aluminum adhesive can be commercially available or synthesized; this disclosure does not impose any special restrictions.

[0040] According to this disclosure, the conditions for the hydrothermal crystallization reaction may include: a temperature of 130–180°C and a time of 5–21 days; preferably, the conditions for the hydrothermal crystallization reaction include: a temperature of 130–160°C and a time of 7–17 days; more preferably, the conditions for the hydrothermal crystallization reaction include: a temperature of 150–160°C and a time of 10–17 days.

[0041] According to this disclosure, the method for recovering the product is well known to those skilled in the art. The process may include, after crystallization, cooling the reaction vessel, separating the crystallized product from the mother liquor, washing the solid with deionized water until the pH value is close to 7, drying, and calcining to obtain UZM-8 molecular sieve raw powder. The drying conditions may be: temperature 80–120°C, time 8–24 h; the calcination conditions may be: temperature 540–600°C, time 3–6 h.

[0042] A second aspect of this disclosure provides a UZM-8 molecular sieve prepared by the method described in the first aspect of this disclosure.

[0043] The UZM-8 molecular sieve disclosed herein has a plate-like structure and exhibits high crystallinity, high specific surface area, and high pore volume. Specifically, the crystallinity of the UZM-8 molecular sieve can be above 90%, especially above 92%, and the specific surface area can be between 360 and 500 m². 2 / g, pore volume can range from 0.55 to 0.70 cm³. 3 / g. The SiO2 / Al2O3 (molar ratio) of the UZM-8 molecular sieve disclosed herein can be 18–50.

[0044] In a third aspect, this disclosure provides a catalyst comprising a support and the UZM-8 molecular sieve described in the second aspect of this disclosure.

[0045] According to this disclosure, the UZM-8 molecular sieve content of the catalyst can vary within a wide range. Specifically, based on the dry weight of the catalyst, the UZM-8 molecular sieve content can be 30–90% by weight, preferably 70–80% by weight; the support content can be 10–70% by weight, preferably 20–30% by weight.

[0046] The support can be a common support used in the art for preparing catalysts. For example, the support can be an inorganic oxide. More specifically, the inorganic oxide can be at least one selected from silicon oxide, aluminum oxide, magnesium oxide, zirconium oxide, and titanium oxide. Preferably, the inorganic oxide is aluminum oxide, specifically SB powder, dry adhesive powder, aluminum sol, and boehmite, etc.

[0047] According to this disclosure, the preparation method of the catalyst can be conventional in the art. For example, it may include the steps of mixing, shaping, drying and calcining the UZM-8 molecular sieve with a support; it may also include the step of first performing ammonium exchange on the UZM-8 molecular sieve to reduce the alkali metal content, so that the alkali metal content in the catalyst, calculated as alkali metal oxides, is less than 0.05% by weight.

[0048] The catalyst disclosed herein is suitable for a variety of catalytic reactions, such as the alkylation reaction of benzene and propylene, or other aromatization, cracking, isomerization and other reactions, and has high catalytic activity. Among them, it is particularly suitable for the liquid-phase alkylation reaction of ethylene and benzene.

[0049] This disclosure provides a fourth aspect, which provides the use of the catalyst described in the third aspect of this disclosure in the liquid-phase alkylation reaction of ethylene and benzene.

[0050] According to this disclosure, the application may include: reacting ethylene and benzene in the presence of the catalyst at a reaction temperature of 180–260°C, a reaction pressure of 2.0–4.0 MPa, and a benzene weight hourly space velocity of 1–5 h⁻¹. -1 The alkylation reaction was carried out under the condition that the molar ratio of benzene to ethylene was (2-12):1.

[0051] In a preferred embodiment of this disclosure, the alkylation reaction conditions include: a reaction temperature of 200–260°C, a reaction pressure of 3.0–3.5 MPa, and a benzene weight hourly space velocity of 3 h⁻¹. -1 The molar ratio of benzene to ethylene is 12:1.

[0052] Using the catalyst provided in this disclosure, the process of synthesizing ethylbenzene by liquid-phase alkylation of ethylene and benzene has a higher ethylene conversion and / or selectivity for the target product ethylbenzene.

[0053] The present disclosure will be further illustrated by the following embodiments, but the embodiments do not disclose the scope of the present invention.

[0054] In the examples and comparative examples, the crystallinity of the molecular sieve was tested as follows: The relative crystallinity (RC) of UZM-8 molecular sieve is the ratio of the sum of the peak areas of the five peaks in the calcined sample within the 2θ range of 16–27° to the sum of the corresponding five peak areas of the UZM-8 molecular sieve standard sample (calcined sample) (with crystallinity defined as 100%). The specific surface area and pore volume were tested using a Micromeritic ASAP2010 static nitrogen adsorption instrument. Test conditions: The sample was placed in the sample processing system and evacuated to a vacuum of 1.33 × 10⁻⁶ at 350°C. -2 The sample surface was purified by maintaining a constant temperature and pressure for 15 hours. At a liquid nitrogen temperature of -196℃, the adsorption and desorption amounts of nitrogen on the purified sample were measured under different specific pressures P / P0, yielding adsorption-desorption isotherms. The specific surface area was then calculated using the two-parameter BET formula, and the adsorption amount at specific pressures P / P0 ≈ 0.98 was taken as the pore volume of the sample.

[0055] Example 1

[0056] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.05Al2O3:0.1TMAOH:0.1TEAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated A1. Its XRD test results are as follows: Figure 1 As shown, the product is UZM-8 molecular sieve; the SEM image is as follows. Figure 2 As shown, the molecular sieve has a thin sheet-like structure; the crystallinity, specific surface area and pore volume of the molecular sieve were measured and are listed in Table 1.

[0057] Example 2

[0058] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.05Al2O3:0.1TMAOH:0.05TEAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated A2. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0059] Example 3

[0060] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.05Al2O3:0.1TMAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 100℃ for 16 hours, and calcined at 580℃ for 5 hours to obtain a molecular sieve sample, designated A3. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0061] Example 4

[0062] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyl diethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The resulting raw material mixture had a colloidal molar ratio of SiO2:0.05Al2O3:0.1TEAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 80℃ for 24 hours, and calcined at 600℃ for 3 hours to obtain a molecular sieve sample, designated A4. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0063] Example 5

[0064] Aluminosilicate gel (SiO2 / Al2O3 = 25, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The resulting raw material mixture had a colloidal molar ratio of SiO2:0.04Al2O3:0.1TMAOH:0.1TEAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated A5. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0065] Example 6

[0066] Aluminosilicate gel (SiO2 / Al2O3 = 40, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.025Al2O3:0.15TMAOH:0.15TEAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 110℃ for 15 hours, and calcined at 540℃ for 6 hours to obtain a molecular sieve sample, designated A6. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0067] Example 7

[0068] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.05Al2O3:0.05TMAOH:0.05TEAOH:0.5DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated A7. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0069] Example 8

[0070] Aluminosilicate gel (SiO2 / Al2O3 = 45, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.022Al2O3:0.1TMAOH:0.1TEAOH:0.5DEDMAOH:45H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 17 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 15 hours, and calcined at 550℃ for 6 hours to obtain a molecular sieve sample, designated A8. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0071] Example 9

[0072] The following ingredients were dissolved in deionized water: silica-alumina gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei), and sodium hydroxide (analytical grade, purchased from Sinopharm Chemical Reagent Co., Ltd.). The mixture was stirred and mixed evenly. The molar ratio of the resulting raw material mixture colloid was 0.10 NaOH:SiO2:0.05 Al2O3:0.05 TMAOH:0.05 TEAOH:0.30 DEDMAOH:13 H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150°C for 10 days. After cooling, the product was removed, filtered, and washed to obtain a solid filter cake. This cake was then exchanged twice with a 2 mol / L ammonium nitrate solution at 75°C to ensure that the alkali metal content (calculated as alkali metal oxides) was less than 0.02% by weight. After drying at 120°C for 15 hours and calcining at 550°C for 6 hours, a molecular sieve sample, designated A9, was obtained. Its XRD test results were consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0073] Example 10

[0074] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Marine Chemical Plant, sodium-free), tetrapropylammonium hydroxide (TPAOH, 25 wt%, Bailingwei), tetrabutylammonium hydroxide (TBAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.05Al2O3:0.1TPAOH:0.1TBAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 110℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated A10. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0075] Example 11

[0076] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei), and dimethyldiethylammonium hydroxide (DEDMAOH, 20 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture colloid was SiO2:0.05Al2O3:0.1TMAOH:0.1TEAOH:0.3DEDMAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 165℃ for 6 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated A11. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0077] Comparative Example 1

[0078] UZM-8 molecular sieve was prepared according to the method in Example 2 of CN107661775B. Specifically, silica-alumina gel (SiO2 / Al2O3 = 20, Qingdao Ocean Chemical Plant, sodium-free) and dimethyl diethyl ammonium hydroxide (DEDMAOH, 20% by weight, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The resulting mixture had a colloidal molar ratio of SiO2:0.05Al2O3:0.50DEDMAOH:13H2O. The resulting mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain the molecular sieve sample, designated D1. Its XRD test results are consistent with... Figure 1 Similarly, this indicates that the product is UZM-8 molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0079] Comparative Example 2

[0080] Aluminosilicate gel (SiO2 / Al2O3 = 20, Qingdao Marine Chemical Plant, sodium-free), tetramethylammonium hydroxide (TMAOH, 25 wt%, Bailingwei), and tetraethylammonium hydroxide (TEAOH, 25 wt%, Bailingwei) were dissolved in deionized water and stirred until homogeneous. The molar ratio of the resulting raw material mixture was SiO2:0.05Al2O3:0.25TMAOH:0.25TEAOH:13H2O. The resulting raw material mixture was then transferred to a sealed crystallization vessel and subjected to hydrothermal crystallization at 150℃ for 14 days. After cooling, the product was removed, filtered, washed, dried at 120℃ for 12 hours, and calcined at 550℃ for 5 hours to obtain a molecular sieve sample, designated D2. XRD analysis showed that the product was a Beta molecular sieve. The crystallinity, specific surface area, and pore volume of this molecular sieve were determined and are listed in Table 1.

[0081] Table 1

[0082] Example No. Molecular sieve No. Crystallinity, % Specific surface area, m 2 / g]] Pore volume, cm3 / g 3 / g]]> Example 1 A1 94.2 435 0.67 Example 2 A2 94.9 440 0.70 Example 3 A3 93.8 429 0.69 Example 4 A4 92.9 428 0.67 Example 5 A5 95.4 453 0.68 Example 6 A6 92.7 428 0.67 Example 7 A7 92.3 430 0.68 Example 8 A8 92.1 419 0.65 Example 9 A9 92.5 426 0.66 Example 10 A10 93.9 431 0.69 Example 11 A11 92.7 422 0.67 Comparative Example 1 D1 90.5 410 0.63 Comparative Example 2 D2 90.8 560 0.62

[0083] As can be seen from the results in Table 1, the UZM-8 molecular sieve disclosed in this invention has high crystallinity, high specific surface area and pore volume. In addition, the cost of UZM-8 molecular sieve is reduced by using lower-cost template agents (such as TMAOH, TEAOH, TPAOH and TBAOH) to replace some of the more expensive template agents (DEDMAOH).

[0084] Test Implementation Examples

[0085] Catalysts were prepared using the molecular sieves obtained in the examples and comparative examples, and their alkylation performance was evaluated.

[0086] The method for preparing catalysts using molecular sieves in Examples 1-11 and Comparative Examples 1-2 is as follows: Molecular sieves (80% by weight, dry basis) and dry adhesive powder (70% by weight, dry basis, purchased from Sinopec Catalyst Changling Branch) are mixed evenly. Nitric acid and an appropriate amount of deionized water are then mixed to form a homogeneous liquid and slowly added while mixing evenly. The resulting mixture has the following mass ratio: 70% molecular sieve dry basis : 30% dry adhesive powder dry basis : 100% deionized water (catalyst dry basis = molecular sieve dry basis + support dry basis, defined as 100%). The mixture is then further mixed evenly on an extruder, extruded into strips, dried, and calcined to obtain the catalyst.

[0087] The prepared catalyst was used in the alkylation reaction of benzene and ethylene under the following conditions: benzene weight hourly space velocity (WHSV) 3.0 h⁻¹. -1 The molar ratio of benzene to ethylene was 1:2, the temperature was 220℃, and the pressure was 3MPa. The ethylene conversion rate and ethylbenzene selectivity were calculated according to the following formula, and the results are listed in Table 2.

[0088] Ethylene conversion rate (%) = (Molar amount of ethylene feed - Molar amount of unreacted ethylene) / Molar amount of ethylene feed × 100%

[0089] Ethylbenzene selectivity (%) = (mass fraction of ethylbenzene / (100% - mass fraction of benzene - mass fraction of ethylene)) × 100%

[0090] Table 2

[0091]

[0092]

[0093] As can be seen from the results in Table 2, the catalyst disclosed herein exhibits higher ethylene conversion and / or selectivity for the target product ethylbenzene in the liquid-phase alkylation reaction of ethylene and benzene.

[0094] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0095] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0096] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for preparing UZM-8 molecular sieve, characterized in that, The method includes: A mixture of raw materials containing a silicon-aluminum source, a first template agent, a second template agent, and water is subjected to a hydrothermal crystallization reaction, and the product is recovered. The first template agent is at least one selected from tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide, the second template agent is dimethyldiethylammonium hydroxide, and the molar ratio of the first template agent to the second template agent is (0.25~0.67):

1.

2. The method according to claim 1, wherein, The first template agent is tetramethylammonium hydroxide and tetraethylammonium hydroxide, and the molar ratio of the tetramethylammonium hydroxide to the tetraethylammonium hydroxide is (0.2~2):

1.

3. The method according to claim 1, wherein, The molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 10~100, H2O / SiO2 = 8~50, R / SiO2 = 0.05~1.5, where R represents the total number of moles of the first template agent and the second template agent.

4. The method according to claim 3, wherein, The molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 15~40, H2O / SiO2 = 9~40, R / SiO2 = 0.1~0.9, where R represents the total number of moles of the first template agent and the second template agent.

5. The method according to claim 4, wherein, The molar ratio of the raw material mixture includes: SiO2 / Al2O3 = 15~30, H2O / SiO2 = 10~20, R / SiO2 = 0.3~0.5, where R represents the total number of moles of the first template agent and the second template agent.

6. The method according to claim 1, wherein, The raw material mixture also contains an alkali source, and the molar ratio of the raw material mixture includes: B / SiO2 = 0.05~0.5, where B represents the number of moles of the alkali source.

7. The method according to claim 6, wherein, The alkali source is at least one selected from sodium hydroxide, lithium hydroxide, potassium hydroxide, rubidium hydroxide, and cesium hydroxide.

8. The method according to claim 1, wherein, The silicon-aluminum source is silicon-aluminum adhesive.

9. The method according to claim 1, wherein, The conditions for the hydrothermal crystallization reaction include: a temperature of 130~180°C. o C, the time is 5~21 days.

10. The method according to claim 9, wherein, The conditions for the hydrothermal crystallization reaction include: a temperature of 130~160°C. o C, the time is 7~17 days.

11. The method according to claim 10, wherein, The conditions for the hydrothermal crystallization reaction include: a temperature of 150~160°C. o C, the time is 10~17 days.

12. UZM-8 molecular sieve prepared by the method according to any one of claims 1 to 11.

13. A catalyst, characterized in that, The catalyst contains a support and the UZM-8 molecular sieve as described in claim 12, wherein the content of the UZM-8 molecular sieve is 30-90% by weight, based on the dry weight of the catalyst.

14. The catalyst according to claim 13, wherein, Based on the dry weight of the catalyst, the content of the UZM-8 molecular sieve is 70-80% by weight.

15. The use of the catalyst according to claim 13 or 14 in the liquid-phase alkylation reaction of ethylene and benzene, characterized in that, The application includes: reacting ethylene and benzene in the presence of the catalyst at a reaction temperature of 180-260°C, a reaction pressure of 2.0-4.0 MPa, and a benzene weight hourly space velocity of 1-5 h⁻¹. -1 The alkylation reaction was carried out under the condition that the molar ratio of benzene to ethylene was (2~12):1.

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