High crystallinity fer molecular sieve, method for preparing same, and use thereof

Abstract

The present application relates to the technical field of molecular sieve catalyst preparation, and is a high-crystallinity FER molecular sieve, a preparation method and application thereof, wherein the waste FER molecular sieve catalyst is calcined and ground to obtain a powdery material, the powdery material is added into an alkali solution to obtain a precursor for synthesizing the FER molecular sieve, water, silicon dioxide, alkali and the precursor for synthesizing the FER molecular sieve are mixed to perform aging, the obtained aged gel is subjected to hydrothermal crystallization treatment, and then is filtered, washed and dried to obtain the high-crystallinity FER molecular sieve. The synthesis process of the high-crystallinity FER molecular sieve in the present application is green and environmentally friendly, and the synthesis steps are simple and easy to implement. The present application not only realizes the resource utilization of the waste FER molecular sieve catalyst, reduces the preparation cost of the FER molecular sieve, and obtains the high-crystallinity FER molecular sieve, but also is applied to a light olefin skeletal isomerization reaction, and can improve the conversion rate of n-butene, the selectivity of iso-butene and the service life of the catalyst.

Description

Technical Field

[0001] This invention relates to the field of molecular sieve catalyst technology, specifically a highly crystalline FER molecular sieve, its preparation method, and its applications. Background Technology

[0002] Molecular sieves are mesoporous zeolites with a two-dimensional pore structure. Within the FER zeolite framework, a 10-membered ring straight channel (0.42 × 0.54 nm) parallel to the

[001] direction intersects with an 8-membered ring straight channel (0.35 × 0.48 nm) parallel to the

[010] direction, forming a two-dimensional cross-channel system. A 6-membered ring channel parallel to the 10-membered ring intersects with the 8-membered ring channel, forming an elliptical "magnesium-alkali zeolite cage." Due to its unique pore structure and good hydrothermal and chemical stability, magnesium-alkali zeolite is widely used in the petrochemical industry for olefin isomerization, olefin oligomerization, and aromatic alkylation. Especially in the isomerization reaction of normal olefin skeletons, it exhibits good selectivity and stability for isomeric olefins and has been widely applied in the refining and chemical industries.

[0003] Currently, the oil refining and chemical industry uses a large amount of FER molecular sieve catalysts annually, while also generating a significant amount of spent FER molecular sieve catalysts. These spent catalysts primarily consist of FER molecular sieves, but also contain a certain amount of alumina and organic matter deposited in the catalyst pores. Currently, most of these spent molecular sieve catalysts are treated as industrial solid waste, with a small portion used as additives in building materials. There are currently no literature reports on using spent FER molecular sieve catalysts as raw materials for the synthesis of FER molecular sieves.

[0004] Chinese invention patent CN110526260B discloses a method for synthesizing FER molecular sieves using natural silica-alumina minerals activated by alkali treatment as seed crystals. The method specifically includes the following steps: (1) Activating natural silica-alumina mineral raw materials under the action of an alkali source to prepare activated seed crystals; (2) Mixing an alkali source aqueous solution with an aluminum source until clear and transparent, adding silica sol dropwise and maintaining stirring to prepare a reactant gel, and controlling the elemental composition therein to conform to the composition of the target molecular sieve product; (3) Adding 5% to 8% of the activated seed crystals by mass of the added silica to the reactant gel to prepare a reactant precursor; (4) Placing the reactant precursor in a reaction vessel for crystallization at a crystallization temperature of 150°C to 190°C and a crystallization time of 36h to 72h; (5) Filtering and washing the crystallized product until it is basically neutral, and drying the product to obtain an FER molecular sieve with a crystallinity of 90% to 102%.

[0005] The aforementioned invention patent provides a method for preparing FER molecular sieves. However, this method uses pretreated natural silica-alumina minerals as seed crystals and does not use waste FER molecular sieve catalysts as raw materials. As a result, the production cost is high and the waste FER molecular sieve catalysts cannot be utilized as resources. Summary of the Invention

[0006] This invention provides a highly crystalline FER molecular sieve, its preparation method, and its application, overcoming the shortcomings of the prior art. It can effectively solve the problems of high production cost and the inability to utilize waste FER molecular sieve catalysts.

[0007] One of the technical solutions of this invention is achieved through the following measures: a method for preparing a highly crystalline FER molecular sieve, comprising the following steps: First, calcining and grinding a waste FER molecular sieve catalyst to obtain a powdered material; Second, adding the powdered material to an alkaline solution and stirring to obtain a precursor for FER molecular sieve synthesis; Third, mixing the required amounts of water, silica sol, alkali, and the FER molecular sieve synthesis precursor and stirring evenly to obtain an FER molecular sieve synthesis gel, which is then aged to obtain an aged gel; Fourth, crystallizing the aged gel under hydrothermal conditions to obtain a hydrothermal crystallization product; Fifth, filtering, washing, and drying the hydrothermal crystallization product to obtain a highly crystalline FER molecular sieve.

[0008] The following are further optimizations and / or improvements to one of the above-mentioned technical solutions:

[0009] In the first step above, the spent FER molecular sieve catalyst is not limited to the spent FER molecular sieve catalyst used in the light olefin skeleton isomerization industrial unit, and the calcination temperature is 300℃ to 800℃, the calcination time is 1h to 12h, the calcination atmosphere is a mixture of oxygen and nitrogen, and the oxygen volume content is 0 to 21% of the mixed gas volume content.

[0010] In the second step above, the alkaline solution is one or more of sodium hydroxide solution and potassium hydroxide solution, the mass percentage of the alkaline solution is 2% to 50%, and the treatment temperature is 60℃ to 120℃ and the treatment time is 2h to 12h during the stirring process.

[0011] In the third step above, the alkali is one or more of sodium hydroxide and potassium hydroxide.

[0012] In the third step above, the mass ratio of silicon dioxide in the silica sol to the mass of the powdered material in the first step is 1:10 to 10:1.

[0013] In the third step above, the molar ratio of alkali, silica, FER molecular sieve synthesis precursor and water in the molecular sieve synthesis gel is 0.2 to 0.4:1:20 to 40:400 to 2000.

[0014] In the third step above, the aging temperature is 30℃ to 90℃ and the aging time is 2h to 12h.

[0015] In the fourth step above, the hydrothermal crystallization temperature is 120℃ to 170℃, and the hydrothermal crystallization time is 24h to 60h.

[0016] The second technical solution of the present invention is achieved through the following measures: a method for preparing a highly crystalline FER molecular sieve to obtain a highly crystalline FER molecular sieve.

[0017] The third technical solution of the present invention is achieved through the following measures: the application of a highly crystalline FER molecular sieve in the skeletal isomerization reaction of light olefins.

[0018] This invention utilizes spent FER molecular sieve catalyst as seed crystals to prepare highly crystalline FER molecular sieves, realizing the resource utilization of spent FER molecular sieve catalysts and reducing the preparation cost of FER molecular sieves. Using spent FER molecular sieves as seed crystals and aluminum sources for FER molecular sieve synthesis, highly crystalline FER molecular sieves were prepared under the following conditions: a mass ratio of silica (the raw material) to spent FER molecular sieve catalyst of 1:10 to 10:1; a hydrothermal crystallization temperature of 120℃ to 170℃; and a hydrothermal crystallization time of 24h to 60h. The relative crystallinity of the molecular sieves reached 95% to 110%.

[0019] When this molecular sieve is used as a catalyst in the butene skeletal isomerization reaction, post-etherified C4 is used as the raw material, the reaction temperature is 300℃ to 450℃, the reaction pressure is 0.1MPa to 0.2MPa, and the feed mass hourly space velocity is 2.0 h⁻¹. -1 up to 10.0h -1 The conversion rate of n-butene can reach 30% to 60%, the selectivity of isobutene can reach 85% to 95%, and the catalyst life is long, ranging from 600 to 900 hours.

[0020] When this molecular sieve is used as a catalyst in the pentene skeletal isomerization reaction, post-etherified C4 is used as the raw material, and the reaction temperature is 250℃ to 400℃, the reaction pressure is 0.2MPa to 0.5MPa, and the feed mass hourly space velocity is 2.0 h⁻¹. -1 up to 10.0h -1 The pentene conversion rate can reach 30% to 60%, the isopentene selectivity can reach 85% to 95%, and the catalyst life is 600h to 900h. Detailed Implementation

[0021] This invention is not limited to the following embodiments; specific implementation methods can be determined according to the technical solution of this invention and actual conditions. Unless otherwise specified, all chemical reagents and chemical products mentioned in this invention are well-known and commonly used chemical reagents and chemical products in the prior art; unless otherwise specified, all percentages in this invention are mass percentages; unless otherwise specified, all solutions in this invention are aqueous solutions with water as the solvent.

[0022] The present invention will be further described below with reference to embodiments:

[0023] Example 1: The preparation method of this highly crystalline FER molecular sieve is carried out according to the following steps: First, the waste FER molecular sieve catalyst is calcined and ground to obtain a powdered material; Second, the powdered material is added to an alkaline solution and stirred to obtain a precursor for FER molecular sieve synthesis; Third, the required amounts of water, silica sol, alkali and FER molecular sieve synthesis precursor are mixed and stirred evenly to obtain an FER molecular sieve synthesis gel, which is then aged to obtain an aged gel; Fourth, the aged gel is crystallized under hydrothermal conditions to obtain a hydrothermal crystallization product; Fifth, the hydrothermal crystallization product is filtered, washed and dried to obtain a highly crystalline FER molecular sieve.

[0024] This invention uses spent FER molecular sieve catalysts as seed crystals and aluminum source precursors for FER molecular sieve synthesis. High-crystallinity FER molecular sieves are prepared via hydrothermal synthesis without the use of organic structure-directing agents. The FER molecular sieve synthesis process provided by this invention is green and environmentally friendly, with simple and easy-to-implement steps. The prepared FER molecular sieve has high crystallinity, and as a catalyst, it exhibits excellent performance in the isomerization reaction of light olefin frameworks, effectively solving the problem of resource utilization of spent FER molecular sieve catalysts.

[0025] Example 2: As an optimization of the above example, in the first step, the waste FER molecular sieve catalyst is not limited to the waste FER molecular sieve catalyst used in the light olefin skeleton isomerization industrial unit, and the calcination temperature is 300°C to 800°C, the calcination time is 1h to 12h, the calcination atmosphere is a mixture of oxygen and nitrogen, and the oxygen volume content is 0 to 21% of the mixed gas volume content.

[0026] Example 3: As an optimization of the above example, in the second step, the alkaline solution is one or more of sodium hydroxide solution and potassium hydroxide solution, the mass percentage of the alkaline solution is 2% to 50%, and the treatment temperature is 60°C to 120°C and the treatment time is 2h to 12h during the stirring process.

[0027] Example 4: As an optimization of the above example, in the third step, the alkali is one or more of sodium hydroxide and potassium hydroxide.

[0028] Example 5: As an optimization of the above example, in the third step, the mass ratio of silicon dioxide in the silica sol to the mass of the powdered material in the first step is 1:10 to 10:1.

[0029] Example 6: As an optimization of the above example, in the third step, the molar ratio of alkali, silica, FER molecular sieve synthesis precursor and water in the molecular sieve synthesis gel is 0.2 to 0.4:1:20 to 40:400 to 2000.

[0030] Example 7: As an optimization of the above example, in the third step, the aging temperature is 30°C to 90°C and the aging time is 2h to 12h.

[0031] Example 8: As an optimization of the above example, in the fourth step, the hydrothermal crystallization temperature is 120°C to 170°C, and the hydrothermal crystallization time is 24h to 60h.

[0032] Example 9: The method for preparing highly crystalline FER molecular sieves yields highly crystalline FER molecular sieves.

[0033] Example 10: Application of the highly crystalline FER molecular sieve in the skeletal isomerization reaction of light olefins.

[0034] The catalyst prepared by the FER molecular sieve of this invention through exchange and molding can be used for the skeletal isomerization reaction of light olefins. Typical butene skeletal isomerization reaction conditions are: using post-etherified C4 as raw material, reaction temperature of 300℃ to 450℃, reaction pressure of 0.1MPa to 0.2MPa, and feed mass hourly space velocity of 2.0 h⁻¹. -1 Up to 10.0h -1 Typical pentene skeleton isomerization reaction conditions are: using post-etherified C5 as raw material, reaction temperature of 250℃ to 400℃, reaction pressure of 0.2MPa to 0.5MPa, and feed mass hourly space velocity of 2.0 h⁻¹. -1 Up to 10.0h -1 .

[0035] Example 11: First, 11g of spent FER molecular sieve catalyst was calcined at 550℃ in a mixed atmosphere of oxygen and nitrogen with an oxygen volume fraction of 21% for 4 hours. The calcined FER molecular sieve catalyst was then ground to obtain 10.2g of powdered material. Second, 10.2g of powdered material was added to an alkaline solution prepared from 3g of sodium hydroxide and 180g of water, and hydrothermally treated at 70℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. 30% silica (by mass) was added. 124g of silica sol, 11g of sodium hydroxide, and the precursor for the synthesis of FER molecular sieve obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 40℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 170℃ for hydrothermal crystallization for 36 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S1.

[0036] X-ray diffraction analysis was performed on sample S1, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S1 was calculated to be 97%.

[0037] Example 12: First, 11g of spent FER molecular sieve catalyst was calcined at 550℃ in a mixed atmosphere of oxygen and nitrogen with an oxygen volume fraction of 21% for 4 hours. The calcined FER molecular sieve catalyst was then ground to obtain 10.2g of powdered material. Second, 10.2g of powdered material was added to an alkaline solution prepared from 4.2g of potassium hydroxide and 180g of water, and hydrothermally treated at 70℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. Silica with a mass fraction of 3% was added. 124g of 0% silica sol, 11g of sodium hydroxide, and the precursor for FER molecular sieve synthesis obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 40℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 165℃ for hydrothermal crystallization for 48 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S2.

[0038] X-ray diffraction analysis was performed on sample S2, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S2 was calculated to be 108%.

[0039] Example 13: First, 11.5g of spent FER molecular sieve catalyst was calcined at 550℃ under a nitrogen atmosphere for 6 hours, and then the calcined FER molecular sieve catalyst was ground to obtain 10.5g of ground powder. Second, 10.5g of powder was added to an alkaline solution prepared by 4.2g of potassium hydroxide and 180g of water, and hydrothermally treated at 70℃ for 4 hours with stirring to obtain the precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at a speed of 200 rpm. 124g of silica sol with a silica mass fraction of 30% was added. 7g of sodium hydroxide, 5.6g of potassium hydroxide, and the precursor for FER molecular sieve synthesis obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 40℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 170℃ for hydrothermal crystallization for 48 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S3.

[0040] X-ray diffraction analysis was performed on sample S3, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S3 was calculated to be 106%.

[0041] Example 14: First, 11g of spent FER molecular sieve catalyst was calcined at 550℃ in a mixed atmosphere of oxygen and nitrogen (21% oxygen by volume) for 4 hours. The calcined FER molecular sieve catalyst was then ground to obtain 10.2g of powdered material. Second, 10.2g of powdered material was added to an alkaline solution prepared from 4.2g of potassium hydroxide and 180g of water, and hydrothermally treated at 70℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. 30% silica (by mass) was added. 124g of silica sol, 15.4g of potassium hydroxide, and the precursor for the synthesis of FER molecular sieve obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 40℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 160℃ for hydrothermal crystallization for 55 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S4.

[0042] X-ray diffraction analysis was performed on sample S4, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S4 was calculated to be 110%.

[0043] Example 15: First, 26g of spent FER molecular sieve catalyst was calcined at 550℃ in a mixed atmosphere of oxygen and nitrogen (21% oxygen by volume) for 4 hours. The calcined FER molecular sieve catalyst was then ground to obtain 23g of powdered material. Second, the 23g powdered material was added to an alkaline solution prepared with 6g sodium hydroxide and 180g water, and hydrothermally treated at 70℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. 30% silica (by mass) was then added. 124g of silica sol, 11g of sodium hydroxide, and the precursor for the synthesis of FER molecular sieve obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 60℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 140℃ for hydrothermal crystallization for 48 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S5.

[0044] X-ray diffraction analysis was performed on sample S5, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S5 was calculated to be 98%.

[0045] Example 16: First, 26g of spent FER molecular sieve catalyst was calcined at 550℃ in a mixed atmosphere of oxygen and nitrogen (21% oxygen by volume) for 4 hours. The calcined FER molecular sieve catalyst was then ground to obtain 23g of powdered material. Second, the 23g powdered material was added to an alkaline solution prepared with 8.5g potassium hydroxide and 180g water, and hydrothermally treated at 70℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. 30% silica (by mass) was then added. 124g of silica sol, 11g of sodium hydroxide, and the precursor for the synthesis of FER molecular sieve obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 60℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 150℃ for hydrothermal crystallization for 48 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S6.

[0046] X-ray diffraction analysis was performed on sample S6, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S6 was calculated to be 100%.

[0047] Example 17: First, 26g of spent FER molecular sieve catalyst was calcined at 550℃ under a nitrogen atmosphere for 6 hours, and then the calcined FER molecular sieve catalyst was ground to obtain 23g of ground powder. Second, 23g of powder was added to an alkaline solution prepared with 9.2g of potassium hydroxide and 180g of water, and hydrothermally treated at 90℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. 124g of silica sol with a silica mass fraction of 30% and potassium hydroxide were added. 7g of sodium, 5.6g of potassium hydroxide, and the precursor for FER molecular sieve synthesis obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 60℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 155℃ for hydrothermal crystallization for 50 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S7.

[0048] X-ray diffraction analysis was performed on sample S7, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S7 was calculated to be 106%.

[0049] Example 18: First, 26g of spent FER molecular sieve catalyst was calcined at 550℃ in a mixed atmosphere of oxygen and nitrogen (21% oxygen by volume) for 4 hours. The calcined FER molecular sieve catalyst was then ground to obtain 23g of powdered material. Second, the 23g powdered material was added to an alkaline solution prepared with 9.2g potassium hydroxide and 180g water, and hydrothermally treated at 90℃ for 4 hours with stirring to obtain a precursor for FER molecular sieve synthesis. Third, 190g of water was added to a crystallization reactor, and stirring was started at 200 rpm. 30% silica (by mass) was then added. 124g of silica sol, 15.4g of potassium hydroxide, and the precursor for the synthesis of FER molecular sieve obtained in the second step were mixed and stirred evenly. The mixture was then sealed in a crystallization vessel, and the stirring speed was maintained at 200 rpm. After aging at 60℃ for 6 hours, an aged gel was obtained. In the fourth step, the aged gel was heated to 160℃ for hydrothermal crystallization for 50 hours to obtain a hydrothermal crystallization product. In the fifth step, after the crystallization was completed, the product was cooled to room temperature, filtered, and the filter cake was washed with deionized water until neutral. Finally, the filter cake was dried at 120℃ to obtain a highly crystalline FER molecular sieve. This highly crystalline FER molecular sieve was a sodium-type FER molecular sieve, and the sample was designated as S8.

[0050] X-ray diffraction analysis was performed on sample S8, using FER molecular sieve provided by Nankai University Catalyst Factory as standard, and the relative crystallinity of sample S8 was calculated to be 110%.

[0051] The results of preparing highly crystalline FER molecular sieves according to Examples 11 to 18 of the present invention are shown in Table 1. As can be seen from Table 1, the relative crystallinity of the highly crystalline FER molecular sieves prepared according to the present invention can reach 95% to 110%.

[0052] Example 19: The highly crystalline FER molecular sieves obtained in Examples 11 to 18 were subjected to a liquid-to-solid ratio of 10:1 and an ammonium chloride solution concentration of 1 mol / L at 80°C. -1 Ion exchange was performed for 3 hours, followed by drying and calcination to prepare hydrogen-form FER molecular sieves. Butene framework isomerization catalysts were prepared by pressing the hydrogen-form FER molecular sieves into tablets. The catalysts prepared in the above steps were evaluated for reactivity, selectivity, and lifetime using C4 esters from a refinery as feedstock and a fixed-bed evaluation device with a catalyst loading of 100 mL. The reaction temperature was 350 °C, the reaction pressure was 0.1 MPa, and the mass hourly space velocity (HHSV) was 5.5 h⁻¹. -1 The specific evaluation results are shown in Table 2. As can be seen from Table 2, when the highly crystalline FER molecular sieve of this invention is used as a catalyst in the butene skeletal isomerization reaction, with post-etherified C4 as the raw material, at a reaction temperature of 300℃ to 450℃, a reaction pressure of 0.1MPa to 0.2MPa, and a feed mass hourly space velocity of 2.0 h⁻¹, the optimal conditions are met. -1 up to 10.0h -1 At that time, the conversion rate of n-butene can reach 42% to 46%, the selectivity of isobutene can reach 96%, and the catalyst life is 600h to 720h.

[0053] Example 20: The highly crystalline FER molecular sieves obtained in Examples 11 to 18 were subjected to a liquid-to-solid ratio of 10:1 and an ammonium chloride solution concentration of 1 mol / L at 80°C. -1 Ion exchange was performed for 3 hours, followed by drying and calcination to prepare hydrogen-form FER molecular sieves. Butene framework isomerization catalysts were then prepared by pressing the hydrogen-form FER molecular sieves into tablets. The catalysts prepared in the above steps were evaluated for reactivity, selectivity, and lifetime using C4 esters from a refinery as feedstock and a fixed-bed evaluation device with a catalyst loading of 100 mL. The reaction temperature was 290 °C, the reaction pressure was 0.3 MPa, and the mass hourly space velocity (HHSV) was 5.5 h⁻¹. -1The specific evaluation results are shown in Table 3. As can be seen from Table 3, when this molecular sieve is used as a catalyst in the pentene skeleton isomerization reaction, using post-etherified C4 as the raw material, at a reaction temperature of 250℃ to 400℃, a reaction pressure of 0.2MPa to 0.5MPa, and a feed mass hourly space velocity of 2.0 h⁻¹, the optimal conditions are met. -1 Up to 10.0h -1 The pentene conversion rate can reach 50% to 55%, the isopentene selectivity can reach 96%, and the catalyst life is 600h to 720h.

[0054] In summary, the synthesis process of the high-crystallinity FER molecular sieve in this invention is green and environmentally friendly, and the synthesis steps are simple and easy to implement. It not only realizes the resource utilization of waste FER molecular sieve catalysts and reduces the preparation cost of FER molecular sieves, but also obtains high-crystallinity FER molecular sieves. Furthermore, it can be applied to the skeletal isomerization reaction of light olefins, which can improve the conversion rate of n-butene, the selectivity of isobutene, and the catalyst lifetime.

[0055] The above technical features constitute the embodiments of the present invention, which have strong adaptability and implementation effect. Unnecessary technical features can be added or removed according to actual needs to meet the needs of different situations.

Claims

1. A process for the preparation of a high crystallinity FER molecular sieve, characterized by The following steps are taken: First, the waste FER molecular sieve catalyst is calcined and ground to obtain a powder material, wherein the waste FER molecular sieve catalyst is not limited to the waste FER molecular sieve catalyst used in the light olefin skeletal isomerization industrial device, the calcination temperature is 300-800℃, the calcination time is 1-12h, and the calcination atmosphere is a mixture of oxygen and nitrogen, with the oxygen volume content being 0-21% of the volume content of the mixed gas; Second, the powder material is added to an alkali solution and stirred to obtain a precursor for FER molecular sieve synthesis; Third, the required amount of water, silica sol, alkali, and precursor for FER molecular sieve synthesis are mixed and stirred uniformly to obtain a FER molecular sieve synthesis gel, which is then aged to obtain an aged gel, wherein the mass ratio of silica in the silica sol to the mass of the powder material in the first step is 1:10 to 10:1, the aging temperature is 30-90℃, and the aging time is 2-12h; Fourth, the aged gel is crystallized under hydrothermal conditions to obtain a hydrothermal crystallization product; Fifth, the hydrothermal crystallization product is filtered, washed, and dried to obtain a high-crystallinity FER molecular sieve.

2. The method of claim 1, wherein In the second step, the alkali solution is one or more of sodium hydroxide solution and potassium hydroxide solution, the mass percentage of the alkali solution is 2-50%, and during the stirring treatment, the treatment temperature is 60-120℃, and the treatment time is 2-12h.

3. The method of claim 1 or 2, wherein In the third step, the alkali is one or more of sodium hydroxide and potassium hydroxide.

4. The method of claim 3, wherein In the third step, the molar ratio of alkali, silica, precursor for FER molecular sieve synthesis, and water in the molecular sieve synthesis gel is 0.2-0.4:1:20-40:400-2000.

5. The method of claim 1 or 2 or 4, wherein In the fourth step, the hydrothermal crystallization temperature is 120-170℃, and the hydrothermal crystallization time is 24-60h.

6. A high-crystallinity FER molecular sieve obtained by the method according to any one of claims 1-5.

Images