A modified beta zeolite

Abstract

The application provides a modified BETA zeolite, and a preparation method thereof is as follows: step 1, a BETA zeolite molecular sieve with a silicon-aluminum ratio of 50 is ultrasonically treated with a sodium hydroxide solution at a liquid-solid ratio of 5-40 mL / g for 1-24 hours, and then is placed for 0.5-2 hours, wherein the concentration of the sodium hydroxide solution is 0.1-5 mol / L, and the treatment temperature is 20-150 DEG C; step 2, the BETA zeolite molecular sieve treated in step 1 is collected, is subjected to suction filtration, is washed, is dried, is treated with an NH4NO3 solution, and is calcined to obtain modified I zeolite; step 3, the modified I zeolite is added into a zinc nitrate solution at a liquid-solid ratio of 5-40 mL / g, is stirred for 2-24 hours, and then is placed for 0.5-2 hours, wherein the concentration of the zinc nitrate solution is 0.1-3 mol / L, and the treatment temperature is 20-150 DEG C; and step 4, the modified I zeolite treated in step 3 is collected, is subjected to suction filtration, is washed, is dried, and is calcined to obtain modified II zeolite. The modified BETA zeolite can be used in a C16-C18 Fischer-Tropsch oil raw material isomerization reaction, and the service life of a catalyst is improved.

Description

Technical Field

[0001] This invention relates to a BETA zeolite, and more particularly to a modified BETA zeolite. Background Technology

[0002] Isomerization reactions of olefins include skeletal isomerization and double bond isomerization. Internal olefins prepared by the isomerization of C16-C18 olefins can be used as raw materials for the synthesis of ASA, exhibiting high purity, good quality, and a simple synthetic process. Furthermore, olefin isomerization processes are also commonly used in the fragrance and pharmaceutical industries.

[0003] In the isomerization of low-carbon olefins, gas-phase reactions are typically conducted under harsh conditions, including high temperature and pressure. This necessitates high reaction temperatures, leading to high energy consumption and demanding equipment requirements. Furthermore, isomerization of olefins with lower carbon numbers is usually investigated because the isomerized products have relatively simpler compositions, making them easier to analyze and control. Since isomerized products consist of skeletal isomers and double bond isomers, the C16-C18 olefin isomers studied in this paper require a certain proportion of both skeletal and double bond isomers. Higher carbon numbers result in more complex compositions, making analysis and control more difficult and requiring higher catalyst performance.

[0004] 1. Gas-phase isomerization of low-carbon olefins

[0005] Currently, olefin isomerization reactions mainly occur in low-carbon-number olefins. These reactions are typically gas-phase reactions with stringent conditions such as reaction temperature and pressure, requiring high reaction temperatures and the addition of carrier gas, which leads to high energy consumption and complex reaction operations.

[0006] Zhang Lixia et al. successfully synthesized the YZ-2 type n-butene isomerization catalyst. Using etherified mixed C4 as raw material, and without any dilution gas, the catalytic performance of the YZ-2 type catalyst for the framework isomerization of n-butene was investigated in a fixed-bed reactor. Evaluation results showed that the synthesized YZ-2 type catalyst exhibited excellent catalytic performance in the n-butene isomerization reaction. Under conditions of a mass hourly space velocity (WHSV) of 1.0 h⁻¹, a reaction temperature of 320–380 °C, a reaction pressure of atmospheric pressure, and without any dilution gas, the single-pass conversion rate of the catalyst was 35%–50%, and the single-pass yield of isobutene reached 34%. The catalyst also showed good stability.

[0007] Peng Wenyu et al. used model compounds n-heptane and n-hexene as raw materials to investigate the catalytic performance of ZSM-35 molecular sieves after secondary modification with different magnesium species on the isomerization reaction. The volume fraction of n-hexene in the raw materials was 10%, the reaction temperature was 400℃, the pressure was 0.4 MPa, the mass hourly space velocity ratio of catalyst to raw materials was 12.8 h⁻¹, and the hydrogen hourly space velocity of the carrier gas was 3600 h⁻¹.

[0008] Gajda et al. used synthesized SAPO-11 molecular sieve as an isomerization catalyst and 38% 1-pentene as a starting material to investigate the effect of reaction temperature on the conversion and selectivity of olefin isomerization. The results showed that under reaction conditions of 327℃ and 1 MPa, the olefin conversion was 64.4%, and the selectivity for isomerized C5 olefins reached 94.6%. When the reaction temperature was changed to 427℃, the olefin conversion increased to 68.7%, but the selectivity for isomerized C5 olefins decreased to 91.5%.

[0009] 2. BETA zeolite modification

[0010] Currently, olefin isomerization reactions can be achieved through methods such as acid catalysis, base catalysis, noble metal compound catalysis, transition metal compound catalysis, and molecular sieve catalysis. Among molecular sieve catalysts, non-zeolite molecular sieves have a relatively low catalytic range and are mainly used for low-carbon chain olefin reactions. Zeolite molecular sieves have stronger catalytic activity and can catalyze the isomerization of terminal olefins with 4-20 straight-chain carbon atoms, but the acidity and acid strength of the catalyst need to be modified and adjusted to the range required for the reaction.

[0011] BETA zeolite is a microporous zeolite with a three-dimensional 12-membered ring cross-pore structure, with silicon (aluminum) oxygen tetrahedra forming the molecular sieve framework. Because BETA zeolite only has cross-channels and lacks a cage-like structure, it readily undergoes ion exchange and has a wide range of applications in catalysis. Currently, research on the modification of BETA zeolite mainly focuses on the following aspects: ion exchange modification, hydrothermal modification, and acid modification. Through modification treatment, the silicon-aluminum ratio and pore structure of BETA zeolite can be altered, thereby adjusting the number and strength of zeolite acid centers, stability, and improving the catalytic performance of the zeolite.

[0012] (1) Hydrothermal modification of BETA zeolite

[0013] Hydrothermal modification is a common modification method that involves treating zeolite with high-temperature steam to remove aluminum atoms, thereby altering the zeolite's silicon-to-aluminum ratio, pore structure, and acid properties to achieve the modification objective.

[0014] Liu Zhihua et al. used high-temperature steam to hydrothermally modify H-type BETA zeolite, catalyzing the reaction of ethanol and tert-butyl alcohol to synthesize ethyl tert-butyl ether, and investigated the relationship between hydrothermal temperature and zeolite catalytic performance. Experimental results showed that when the temperature T < 600℃, the catalytic activity increased with increasing temperature; however, when the temperature T > 600℃, further increases in temperature led to a decrease in catalytic activity. This is because excessively high temperatures cause the molecular sieve framework structure to collapse, pores to become blocked, and active centers to be covered, thus reducing catalytic activity.

[0015] Dai Shaoyong investigated the effects of hydrothermal treatment on the acid properties of H-type BETA zeolite at different temperatures. The results showed that the zeolite crystal structure remained largely unchanged after hydrothermal treatment, but the acid content decreased. The higher the treatment temperature, the greater the decrease in acid content, leading to a decline in catalytic activity. Considering both zeolite stability and product yield, 300℃ was determined to be the optimal hydrothermal temperature.

[0016] Wang Li et al. hydrothermally modified BETA zeolite to catalyze the etherification reaction of methanol and isobutylene, synthesizing methyl tert-butyl ether (MTBE), an additive for unleaded gasoline. Experiments showed that the modified zeolite exhibited high catalytic activity, with MTBE selectivity approaching 100%. Furthermore, heat treatment conditions significantly influenced the catalytic performance of BETA zeolite; pretreatment at 550℃ followed by hydrothermal treatment at 350℃ for 3 hours resulted in the highest catalytic activity.

[0017] Hydrothermal modification can usually increase the silica-alumina ratio and pore structure of zeolite, as well as reduce the acid content of zeolite, but it is easy to damage the zeolite's own structure and cannot flexibly control its acid strength and acid type.

[0018] (2) Acid modification

[0019] Acid modification is a common modification method that involves treating zeolite with acid solution to remove aluminum, thereby altering the pore structure and the number and strength of acid centers in the zeolite, and improving the catalytic performance of the zeolite to adapt to a wider range of catalytic reactions.

[0020] Liu Aiquan used hydrochloric acid of different concentrations to acid-modify H-type BETA zeolite and applied it to the isomerization reaction of o-xylene. Experimental results showed that low-concentration hydrochloric acid mainly removed non-framework aluminum and transition-state aluminum from the zeolite, while high-concentration hydrochloric acid was required to remove framework aluminum atoms. After acid modification, the non-framework aluminum in the zeolite was washed away by hydrochloric acid, exposing the covered catalytic active centers and clearing blocked pores, thus improving the catalytic activity of the modified zeolite.

[0021] Cao Yayun treated BETA zeolite with oxalic acid, malic acid, and tartaric acid, respectively, and evaluated the catalytic performance of the modified zeolite through the esterification reaction of acetic acid and n-butanol. A series of characterizations revealed that the number of hydroxyl groups in the organic acid affects the properties of the modified zeolite; the more hydroxyl groups, the greater the dealumination and the greater the change in acidity.

[0022] Xie Zaiku et al. used an ion exchange method to treat BETA zeolite with NH4NO3 and citric acid, and characterized the acidity of H-type BETA by infrared spectroscopy, NH3-TPD, AlNMR, and SiNMR. NH3-TPD results showed that citric acid modification could simultaneously increase the acidity of both strong and weak acids in the zeolite. Furthermore, AlNMR characterization revealed that citric acid has a dual effect of dealumination and aluminum replenishment, with the dealumination sites being Si(2Al) sites and the aluminum replenishment sites being Si(OAl).

[0023] Acid modification primarily serves to remove aluminum, altering the acid content of the catalyst, but it's difficult to specifically adjust the acid content for different strengths. Furthermore, acid modifiers are typically strong acids, which, while removing skeletal aluminum, can also cause the zeolite framework to collapse, leading not only to decreased crystallinity but also to the formation of amorphous substances that clog zeolite pores.

[0024] (3) Ion exchange modification

[0025] Ion exchange modification mainly refers to replacing the equilibrium ions Na+ or framework Al atoms in zeolite with NH4+ or other metal ions, thereby changing the pore size and surface acid-base properties of zeolite and improving the catalytic performance of zeolite molecular sieves.

[0026] Huang Xinjiang et al. modified BETA zeolite with La and Fe using an impregnation method to catalyze the alkylation reaction of benzene and n-butene. Experimental results showed that although the surface acidity of the zeolite decreased after La and Fe modification, the catalytic activity was significantly improved. The La / BETA zeolite exhibited slightly higher catalytic activity for the alkylation reaction than the Fe / BETA zeolite.

[0027] Li et al. pretreated BETA zeolite with oxalic acid and then prepared modified zeolite Mg-Beta by impregnation to catalyze the hexene isomerization reaction. Experimental results showed that the introduction of magnesium modulates the acid content and acid center distribution of the zeolite, thereby affecting its catalytic activity, and also enhances its stability and prolongs its lifespan.

[0028] Vesselina et al. prepared In / H-Beta molecular sieves with different indium contents using a solid-state ion exchange method and applied them to the isomerization reaction of m-xylene. Experimental results showed that indium atoms, as Lewis acids, are the active centers of the catalyst. In an inert atmosphere, the addition of indium significantly improved the stability of the catalyst and the selectivity of the products.

[0029] Although ion exchange modification can introduce some metal ions to modulate the acid content and acid center distribution of zeolite, it is difficult to improve the control of zeolite channels. Some large molecular reactants are difficult to enter the channels, which can easily cause channel blockage and reduce catalytic activity.

[0030] The above methods have the following main drawbacks:

[0031] (1) Current olefin isomerization reactions mainly occur in low-carbon olefins, which are usually gas-phase reactions with relatively harsh conditions such as reaction temperature and pressure. The high reaction temperature results in high energy consumption and higher equipment requirements. In addition, the reaction process requires the addition of a carrier gas, which makes the reaction operation more complicated. Correspondingly, the isomerization of high-carbon olefins may require even higher reaction temperatures and more stringent conditions.

[0032] (2) Hydrothermal modification can usually increase the silica-alumina ratio and pore structure of zeolite, as well as reduce the acid content of zeolite, but it is easy to damage the structure of zeolite itself and cannot flexibly control its acid strength and acid type.

[0033] (3) Acid modification mainly plays the role of aluminum removal and can change the acid content of the catalyst, but it is difficult to adjust the acid content of different acid strengths in a targeted manner. In addition, acid modifiers are usually strong acids. While removing skeletal aluminum, strong acids will also cause the zeolite skeleton to collapse, which will not only lead to a decrease in crystallinity, but the amorphous substances produced will also block the zeolite channels.

[0034] (4) Although the ion exchange modification method can introduce some metal ions to achieve the function of adjusting the acid content and acid center distribution of zeolite, it is difficult to improve the control of zeolite channels. Some macromolecular reactants are difficult to enter the channel, which can easily cause channel blockage and reduce catalytic activity.

[0035] This invention utilizes modified BETA zeolite for the liquid-phase isomerization reaction of high-carbon-number olefins, overcoming the aforementioned defects. Summary of the Invention

[0036] This invention utilizes modified BETA zeolite for the liquid-phase isomerization reaction of high-carbon-number olefins. First, as a liquid-phase reaction, the reaction temperature and pressure are relatively low, resulting in lower energy consumption requirements and the absence of large amounts of high-temperature byproducts. Second, the BETA zeolite modified by alkali treatment has enlarged pores, which can accommodate the isomerization reaction of relatively large C16-C18 Fischer-Tropsch oil feedstocks, reducing the likelihood of pore blockage. Third, by modifying BETA zeolite with Zn, strong and weak acids are converted to acid strengths suitable for this reaction, allowing for the control of the composition of the isomerized product to obtain the desired product composition. Fourth, during the reaction, the catalyst activity can be enhanced by adjusting the reaction temperature, thereby controlling the composition of the isomerized product and extending the catalyst lifetime.

[0037] This invention provides a modified BETA zeolite, the preparation method of which is as follows:

[0038] Step 1: According to the liquid-to-solid ratio of 5-40 mL / g, ultrasonically treat BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 with sodium hydroxide solution for 1-24 hours, and then let it stand for 0.5-2 hours. The concentration of sodium hydroxide solution is 0.1-5 mol / L, and the treatment temperature is 20-150℃.

[0039] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0040] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 5-40 mL / g, stir for 2-24 h, and then let stand for 0.5-2 h. The concentration of the zinc nitrate solution is 0.1-3 mol / L, and the treatment temperature is 20-150℃.

[0041] Step 4: After collecting and filtering the modified I zeolite processed in Step 3, wash, dry, and calcine it to obtain modified II zeolite.

[0042] The preferred embodiment is that the washing in step 2 is to use deionized water for washing, rinsing repeatedly 3-5 times until the pH is close to neutral.

[0043] The drying in step 2 involves drying the washed BETA zeolite molecular sieve at 150°C for 4 hours.

[0044] The NH4NO3 solution treatment in step 2 involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution, stirring at 80°C for 4 hours at a solid-liquid ratio of 1:80 g / mL, repeating the process 3 times, filtering and washing until neutral.

[0045] The roasting in step 2 refers to roasting at 500℃ for 4 hours.

[0046] The preferred embodiment is that the washing in step 4 is to use deionized water for washing, rinsing repeatedly 3-5 times until the pH is close to neutral.

[0047] The drying and calcination in step 4 refers to drying the water-washed modified I zeolite at 150°C for 4 hours, and then calcining it at 500°C for 4 hours to obtain modified II zeolite.

[0048] The preferred embodiment is that, in step 1, the liquid-to-solid ratio is 15-20 mL / g, the concentration of the sodium hydroxide solution is 1.2 mol / L, the treatment time is 2-8 h, and the treatment temperature is 60 °C.

[0049] In step 3, the liquid-to-solid ratio is 15-18 mL / g, the sodium hydroxide solution concentration is 0.4 mol / L, the treatment time is 7-8 h, and the treatment temperature is 20-70 °C.

[0050] The preferred embodiment is that in step 1, the liquid-to-solid ratio is 15 mL / g, the concentration of the sodium hydroxide solution is 1.2 mol / L, the treatment time is 8 h, and the treatment temperature is 60 °C.

[0051] In step 3, the liquid-to-solid ratio is 18 mL / g, the sodium hydroxide solution concentration is 0.4 mol / L, the treatment time is 8 h, and the treatment temperature is 70 °C.

[0052] The modified BETA zeolite provided by this invention has the following excellent effects:

[0053] 1. A modified BETA zeolite is provided for use in the liquid-phase isomerization reaction of high carbon number olefins.

[0054] 2. The alkaline solution selectively dissolves the framework silicon in the zeolite molecular sieve, causing the framework aluminum to migrate to the surface. This results in the formation of an aluminum shell on the outer surface of the molecular sieve, creating pores of different sizes inside the molecular sieve. This expands the pores of the zeolite, making it easier for large molecular reactants to enter.

[0055] 3. Metallic zinc (Zn) is inexpensive and possesses excellent hydrogen transfer capabilities. Modification with Zn weakens the strength and quantity of strong zeolite acids, while increasing the strength of weak acids. This increases the proportion of acids with relatively suitable strength for the reaction, resulting in a good catalytic effect on the isomerization of high-carbon-number olefins.

[0056] 4. By controlling the reaction temperature online, the acidity of the catalyst can be indirectly controlled, enabling it to meet the requirements of the isomerization product. Temperature control continuously enhances the catalyst's activity and extends its lifespan.

[0057] 5. Although it is a high carbon number isomerization reaction, as a liquid-phase reaction, the reaction temperature and pressure are relatively low, the energy consumption requirements of the equipment are low, and no carrier gas is required, making the operation simple. Attached Figure Description

[0058] Figure 1 NH3-TPD diagrams for comparative examples and Example 1;

[0059] Figure 2 This is a comparative aperture distribution diagram;

[0060] Figure 3 This is a pore size distribution diagram for Example 1. Detailed Implementation

[0061] The present invention will be further described in detail below through embodiments, which are intended to illustrate the invention and not limit it. It should be noted that those skilled in the art can make various improvements and modifications to the present invention without departing from the principles of the invention, and these improvements and modifications also fall within the protection scope of the present invention.

[0062] Example 1

[0063] A modified BETA zeolite, the preparation method of which is as follows:

[0064] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0065] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0066] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0067] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 70℃.

[0068] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0069] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0070] Example 2

[0071] A modified BETA zeolite, the preparation method of which is as follows:

[0072] Step 1: According to the liquid-to-solid ratio of 20 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0073] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0074] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0075] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 15 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 70℃.

[0076] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0077] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0078] Example 3

[0079] A modified BETA zeolite, the preparation method of which is as follows:

[0080] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 2 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0081] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0082] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0083] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 7 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 70℃.

[0084] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0085] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0086] Example 4

[0087] A modified BETA zeolite, the preparation method of which is as follows:

[0088] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0089] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0090] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0091] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 20℃.

[0092] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0093] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0094] Example 5

[0095] A modified BETA zeolite, the preparation method of which is as follows:

[0096] Step 1: According to the liquid-to-solid ratio of 5 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0097] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0098] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0099] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 40 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 70℃.

[0100] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0101] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0102] Example 6

[0103] A modified BETA zeolite, the preparation method of which is as follows:

[0104] Step 1: According to the liquid-to-solid ratio of 40 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0105] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0106] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0107] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 5 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 70℃.

[0108] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0109] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0110] Example 7

[0111] A modified BETA zeolite, the preparation method of which is as follows:

[0112] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 0.1 mol / L, and the treatment temperature was 60℃.

[0113] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0114] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0115] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 3 mol / L, and the treatment temperature is 70℃.

[0116] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0117] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0118] Example 8

[0119] A modified BETA zeolite, the preparation method of which is as follows:

[0120] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 5 mol / L, and the treatment temperature was 60℃.

[0121] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0122] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0123] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.1 mol / L, and the treatment temperature is 70℃.

[0124] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0125] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0126] Example 9

[0127] A modified BETA zeolite, the preparation method of which is as follows:

[0128] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 is ultrasonically treated with sodium hydroxide solution for 1 hour, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution is 1.2 mol / L, and the treatment temperature is 60℃.

[0129] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0130] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0131] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 24 h, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 70 °C.

[0132] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0133] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0134] Example 10

[0135] A modified BETA zeolite, the preparation method of which is as follows:

[0136] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 24 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 60℃.

[0137] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0138] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0139] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 150℃.

[0140] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0141] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0142] Example 11

[0143] A modified BETA zeolite, the preparation method of which is as follows:

[0144] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 20℃.

[0145] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0146] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0147] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 150℃.

[0148] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0149] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0150] Example 12

[0151] A modified BETA zeolite, the preparation method of which is as follows:

[0152] Step 1: According to the liquid-to-solid ratio of 15 mL / g, BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 was ultrasonically treated with sodium hydroxide solution for 8 hours, and then allowed to stand for 1 hour. The concentration of sodium hydroxide solution was 1.2 mol / L, and the treatment temperature was 150℃.

[0153] Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite.

[0154] The washing process involves rinsing with deionized water 3-5 times until the pH is close to neutral. Drying involves drying the washed BETA zeolite molecular sieve at 150℃ for 4 hours. NH4NO3 solution treatment involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution at a solid-liquid ratio of 1:80 g / mL, stirring at 80℃ for 4 hours, repeating this process 3 times, filtering, and washing until neutral. Calcination involves calcining at 500℃ for 4 hours.

[0155] Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 18 mL / g, stir for 8 hours, and then let stand for 1 hour. The concentration of the zinc nitrate solution is 0.4 mol / L, and the treatment temperature is 20℃.

[0156] Step 4: Collect the modified I zeolite processed in Step 3, filter it, wash it, dry it, and calcine it to obtain modified II zeolite.

[0157] The washing process involves rinsing with deionized water, repeating the rinsing 3-5 times until the pH is close to neutral. The drying and calcining process involves drying the water-washed modified I zeolite at 150℃ for 4 hours, and then calcining it at 500℃ for 4 hours to obtain modified II zeolite.

[0158] Example 13

[0159] The modified BETA zeolite prepared in Examples 1-12 and the BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 were used as catalysts (comparative examples) to carry out the isomerization reaction of C16-C18 olefins and test the service life of the catalysts.

[0160] The specific steps are as follows:

[0161] 1. Catalyst loading and activation: The modified BETA zeolite prepared in Examples 1-12 and BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 were loaded into the reactor as catalysts, and quartz wool and quartz sand were added at the top and bottom for filling.

[0162] 2. After filling, control the reactor temperature at 300℃ and activate it online with nitrogen for 12 hours;

[0163] 3. High carbon number olefin feedstock (C16-C18) undergoes dehydration and oxygen-containing compound removal treatment, with water content less than 100ppm and carbonyl groups less than 20ug / ml;

[0164] 4. Calibrate the liquid transfer pump, reactor heating, feeding, and sampling analysis; the reaction temperature is 140-190℃, atmospheric pressure, and mass hourly space velocity (MHV) is 3 h⁻¹. -1 .

[0165] The cumulative lifespan of the catalyst was tested using gas chromatography: column type: DB-XLB; separation conditions: split ratio 100:1, held at 50℃ for 5 min, increased from 50℃ to 260℃ at a rate of 5℃ / min, held for 5 min, then increased from 260℃ to 300℃ at a rate of 20℃ / min, held for 10 min. Column flow rate: 0.75 ml / min.

[0166] The cumulative lifespan of the catalyst is shown in the table below:

[0167]

[0168]

[0169] Conclusions from the comparison of examples:

[0170] 1. Example 1 represents a more optimized modification condition.

[0171] 2. Comparison of Examples 2, 5, and 6 with Example 1 revealed the following: (1) In the pore control step, if the liquid-to-solid ratio is too small, the pore expansion effect will be significantly weakened and the lifespan will be reduced; if the liquid-to-solid ratio is too large, the pore expansion effect will be too strong, some pores will be damaged, and the lifespan will be reduced. (2) In the acid control step, if the liquid-to-solid ratio is too small, the proportion of medium-strong acid will be too low, and the lifespan will be greatly reduced; if the liquid-to-solid ratio is too large, the proportion of medium-strong acid will not change much and may be blocked on the pore surface, and the catalyst lifespan will be reduced.

[0172] 3. Comparison of Examples 3, 9, and 10 with Example 1 revealed the following: (1) In the pore control step, if the time is too short, the pore expansion effect will be significantly weakened and the lifespan will be reduced; if the time is too long, the pore expansion effect will be too strong, some pores will be damaged, and the lifespan will be reduced. (2) In the acid control step, if the time is too short, the proportion of medium and strong acids will be reduced, and the lifespan will be greatly reduced; if the time is too long, the proportion of medium and strong acids will not change much and may cause blockage on the surface and inside of the pores, and the catalyst lifespan will be reduced.

[0173] 4. Comparison of Examples 4, 11, and 12 with Example 1 revealed the following: (1) In the pore control step, if the temperature is too low, the pore expansion effect will be significantly weakened and the lifespan will be reduced; if the temperature is too high, the pore expansion effect will be too strong, some pores will be damaged, and the lifespan will be reduced; (2) In the acid control step, if the temperature is too low, the proportion of medium and strong acids will be reduced, and the lifespan will be greatly reduced; if the temperature is too high, the proportion of medium and strong acids will not change much and may cause blockage inside the pores, and the catalyst lifespan will be reduced.

[0174] 5. Comparison of Examples 7 and 8 with Example 1 revealed the following: (1) In the pore control step, if the sodium hydroxide concentration is too low, the pore-expanding effect is significantly weakened and the lifespan is reduced; if the sodium hydroxide concentration is too high, some pores are damaged and the lifespan is reduced; (2) In the acid control step, Zn 2+ If the solution concentration is too low, the proportion of moderately strong acids decreases, and the lifespan is significantly reduced; Zn 2+ If the solution concentration is too high, the proportion of medium-strong acid will not change much and may cause pore blockage, reducing the catalyst life.

[0175] Example 14

[0176] The comparative example and Example 1 were tested. Figure 1 The NH3-TPD diagrams are for the comparative example and Example 1. Figure 2 , Figure 3 This is a pore size distribution diagram for comparative example and Example 1.

[0177] Figure 1The black curve represents the NH3-TPD spectrum before BETA zeolite modification. Around 200℃, it indicates a weak acid, while around 400℃ it indicates a strong acid. This shows that the acid distribution before modification is mainly composed of strong and weak acids. The red curve represents the NH3-TPD spectrum after BETA zeolite modification. The acid distribution is mainly concentrated around 260℃, with the strong acid strength decreasing and the weak acid strength increasing, resulting in the suitable acid strength distribution for this reaction.

[0178] Figure 2 The image shows the pore size distribution of BETA zeolite before modification. The pore size is mainly concentrated in the range of 0.6-0.9 nm, which is relatively small and not conducive to the reaction of materials with high carbon number.

[0179] Figure 3 The image shows the pore size distribution of the modified BETA zeolite. It can be seen that in addition to pores of 0.6-0.9 nm, a large number of pores between 2-7 nm also appear, indicating a significant pore-expanding effect, which is suitable for the reaction of high carbon number materials in this reaction.

[0180] The above specific embodiments are merely several optional embodiments of the present invention. Based on the technical solutions of the present invention and the relevant teachings of the above embodiments, those skilled in the art can make various alternative improvements and combinations to the above specific embodiments.

Claims

1. A modified BETA zeolite, the preparation method of which is as follows: Step 1: According to the liquid-to-solid ratio of 5-40 mL / g, ultrasonically treat BETA zeolite molecular sieve with a silicon-to-aluminum ratio of 50 with sodium hydroxide solution for 1-24 hours, and then let it stand for 0.5-2 hours. The concentration of sodium hydroxide solution is 0.1-5 mol / L, and the treatment temperature is 20-150℃. Step 2: Collect the BETA zeolite molecular sieve processed in Step 1, filter it, wash it, dry it, treat it with NH4NO3 solution, and calcine it to obtain modified I zeolite. Step 3: Add the modified zeolite I above to the zinc nitrate solution at a liquid-to-solid ratio of 5-40 mL / g, stir for 2-24 h, and then let stand for 0.5-2 h. The concentration of the zinc nitrate solution is 0.1-3 mol / L, and the treatment temperature is 20-150℃. Step 4: After collecting and filtering the modified I zeolite processed in Step 3, wash, dry, and calcine it to obtain modified II zeolite.

2. The modified BETA zeolite according to claim 1, characterized in that: The washing in step 2 involves rinsing with deionized water, rinsing repeatedly 3-5 times until the pH is close to neutral. The drying in step 2 involves drying the washed BETA zeolite molecular sieve at 150°C for 4 hours. The NH4NO3 solution treatment in step 2 involves adding the dried BETA zeolite molecular sieve to a 1 mol / L NH4NO3 solution, stirring at 80°C for 4 hours at a solid-liquid ratio of 1:80 g / mL, repeating the process 3 times, filtering and washing until neutral. The roasting in step 2 refers to roasting at 500℃ for 4 hours.

3. The modified BETA zeolite according to claim 1, characterized in that: The washing in step 4 involves rinsing with deionized water, rinsing repeatedly 3-5 times until the pH is close to neutral. The drying and calcination in step 4 refers to drying the water-washed modified I zeolite at 150°C for 4 hours, and then calcining it at 500°C for 4 hours to obtain modified II zeolite.

4. A modified BETA zeolite according to any one of claims 1-3, characterized in that: In step 1, the liquid-to-solid ratio is 15-20 mL / g, the sodium hydroxide solution concentration is 1.2 mol / L, the treatment time is 2-8 h, and the treatment temperature is 60 °C. In step 3, the liquid-to-solid ratio is 15-18 mL / g, the sodium hydroxide solution concentration is 0.4 mol / L, the treatment time is 7-8 h, and the treatment temperature is 20-70 °C.

5. A modified BETA zeolite according to claim 4, characterized in that: In step 1, the liquid-to-solid ratio is 15 mL / g, the sodium hydroxide solution concentration is 1.2 mol / L, the treatment time is 8 h, and the treatment temperature is 60 °C. In step 3, the liquid-to-solid ratio is 18 mL / g, the concentration of the sodium hydroxide solution is 0.4 mol / L, the treatment time is 8 h, and the treatment temperature is 70 °C.

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