Preparation method and application of catalyst for removing trace olefins in reforming oil

Abstract

The application discloses a preparation method and application of a catalyst for removing trace olefins in reforming oil, and the preparation method comprises the following steps: (1) uniformly mixing Y type molecular sieve, SAPO-34 molecular sieve, a pore expanding agent and a slip agent into mixed powder; (2) adjusting alumina into glue with an inorganic acid solution, mixing the mixed powder in the step (1) into the glue to uniformly mix and knead, then shaping, drying and calcining to obtain a shaped catalyst; and (3) obtaining a finished catalyst by performing hydrothermal treatment and microwave treatment on the shaped catalyst. The catalyst prepared by the application has the advantages of low price, simple and efficient catalytic reaction system, good stability, mild reaction condition, a bromine index of product below 300 mgBr / 100g after 72h of reaction, small aromatic hydrocarbon loss rate, and little change in the amount of toluene components at the inlet and outlet. The catalyst performance meets the requirement of removing olefins from reforming oil.

Description

Technical Field

[0001] This invention belongs to the field of refining catalyst technology, specifically relating to a method for preparing and applying a catalyst for removing trace amounts of olefins from reformate. Background Technology

[0002] Aromatics are one of the basic raw materials in the petrochemical industry and occupy an extremely important position in chemical products. During production, they typically contain a certain amount of olefin impurities, including monoolefins, dienes, and styrene. These olefin impurities easily polymerize to form gums, affecting the quality of aromatic products. Their presence can also adversely affect some subsequent processes, such as causing coking in high-temperature reactors. Furthermore, in recent years, with the increasing market demand for aromatics, the reaction severity of continuous reforming units has been continuously increasing, leading to a corresponding increase in the olefin content in reformed oils. Therefore, it is necessary to remove these olefin impurities.

[0003] For the deolefination and upgrading of reformed aromatics, there are currently two main industrially widely used methods: hydrorefining and clay refining. Both of these processes are either expensive and complex, or highly environmentally unfriendly, hindering their further industrial application.

[0004] Patent CN101433856.A developed an alkylation catalyst for removing trace amounts of olefins. The modified catalyst contains: (a) 30-70% alumina, (b) 30-70% molecular sieve, and (c) 0-40% a compound selected from one or more elements of lanthanide rare earth, P, W, Nb, and Mo. However, the catalyst activity is generally low.

[0005] Patent CN102008976A uses ReUSY molecular sieve with a high silica-to-alumina ratio as the main active component, mordenite molecular sieve as the second active component, and alumina as the binder, resulting in a high catalyst cost.

[0006] Patent CN102029180A developed a deolefination catalyst: the catalyst comprises molecular sieves, rare earth oxides, alkaline earth metal oxides, phosphorus pentoxide, and alumina. The metal loading methods for the catalyst are ion exchange and impregnation. Rare earth and phosphorus elements are loaded using the ion exchange method, while alkaline earth metals are loaded using an equal-volume impregnation method in the presence of surfactants. The catalyst preparation process is complex.

[0007] Patent CN103495435A developed a reforming oil deolefin removal catalyst. A certain amount of Lewis acid was added to the catalyst, and a certain amount of rare earth metals were loaded onto a molecular sieve catalyst support by impregnation. This resulted in a reforming oil deolefin removal catalyst with high low-temperature catalytic activity, high stability, long service life, and recyclability. However, the catalyst has a high cost.

[0008] The catalyst developed by patent CN105080592A has an average pore size of 5-30 nm. It uses lanthanide elements or mixtures thereof and oxides of one or more elements selected from Ca, Zn, Mg, and Ti, as well as at least one selected from mordenite, Y zeolite, ZSM-5 molecular sieve, MCM-22 molecular sieve, MCM-56 molecular sieve, and β molecular sieve. The support is selected from alumina and silica or mixtures thereof. This technical solution can be used in the industrial production of aromatic hydrocarbons reducing olefins. However, the preparation process is relatively complex and the active components of the catalyst are lost quickly.

[0009] Patents CN107754845B and CN107754846B respectively use USY and Y molecular sieve modified catalysts. The USY catalyst is added with solid superacids and group I and II elements, while the Y catalyst is added with lanthanide elements and one or more of Na, K, Mg, Ca, Sr, Ba, Ga, Sn, In, Ge, and Bi elements. The preparation cost of the catalyst is relatively high.

[0010] Patent CN105087049A discloses a method for suppressing side reactions in the aromatic hydrocarbon deolefination process. In the aromatic hydrocarbon deolefination reaction, water or reversibly adsorbed acid inhibitors, such as thiols, thioethers, pyridine, quinoline, and isoquinoline, are injected into the solid acid catalyst bed. The solid acid catalyst includes at least one selected from mordenite, Y zeolite, ZSM-5 molecular sieve, MCM-22 molecular sieve, MCM-56 molecular sieve, ZSM-12 molecular sieve, SAPO-11 molecular sieve, SAPO-34 molecular sieve, and β molecular sieve, as well as an active element. The catalyst has a certain amount of strong acid centers, and the presence of strong acid centers can lead to some cracking side reactions in the early stage of operation. Summary of the Invention

[0011] The purpose of this invention is to provide a method for preparing a catalyst for removing trace amounts of olefins from reformate, so as to solve the problems of complex and costly catalyst preparation methods in the prior art.

[0012] Another objective of this invention is to provide an application of a catalyst for removing trace amounts of olefins from reformate.

[0013] To achieve the above objectives, the present invention provides a method for preparing a catalyst for removing trace amounts of olefins from reformate, comprising the following steps:

[0014] (1) Mix Y-type molecular sieve, SAPO-34 molecular sieve, pore expander and extrusion aid evenly to form a mixed powder;

[0015] (2) The small-pore alumina is mixed into a gel with an inorganic acid solution. The mixed powder in step (1) is added to the gel for mixing, wetting and kneading until uniform. Then it is shaped, dried and calcined to obtain the shaped catalyst.

[0016] (3) The shaped catalyst is subjected to hydrothermal treatment and microwave treatment to obtain the finished catalyst.

[0017] The preparation method of the catalyst for removing trace amounts of olefins from reformed oil according to the present invention, wherein the mass ratio of the Y-type molecular sieve to the SAPO-34 molecular sieve is 100:1~5.

[0018] The method for preparing the catalyst for removing trace amounts of olefins from reformed oil according to the present invention has a silicon-to-aluminum ratio of 7.0 to 8.5 for the Y-type molecular sieve.

[0019] The method for preparing a catalyst for removing trace amounts of olefins from reformed oil according to the present invention comprises: pore-expanding agent being guar gum powder; extrusion aid being citric acid; guar gum powder being 1-3 wt% of the total mass of Y-type molecular sieve and SAPO-34 molecular sieve; and citric acid being 2-4 wt% of the total mass of Y-type molecular sieve and SAPO-34 molecular sieve.

[0020] The method for preparing the catalyst for removing trace amounts of olefins from reformed oil according to the present invention comprises a mass ratio of alumina to mixed powder of 1:0.6~0.9, and a mass ratio of inorganic acid solution to catalyst powder of 1:0.8~2.0.

[0021] The preparation method of the catalyst for removing trace amounts of olefins from reformed oil according to the present invention includes the following steps: in step (2), drying is performed by first air drying at 18~30℃ and then drying at 90~120℃ for 8~16h; and calcination is performed by calcination at 400~650℃ for 2.5~6.5h.

[0022] The preparation method of the catalyst for removing trace amounts of olefins from reformed oil according to the present invention, wherein the hydrothermal treatment conditions in step (3) are 600~700℃, 5~7Mpa, and 3~5 hours of hydrothermal treatment.

[0023] The preparation method of the catalyst for removing trace amounts of olefins from reformed oil according to the present invention, wherein the microwave treatment conditions in step (3) are microwave cleaning at 30~50℃ for 3~5 hours.

[0024] To achieve the above objectives, the present invention also provides an application of the catalyst prepared by the above method in the removal of trace olefins from reformate, wherein the bromine index of the reformate is 800~1200 mgBr / 100g, the reaction temperature is 130℃~220℃, the reaction pressure is 1.0~2.0MPa, and the reaction space velocity is 0.5~20 h⁻¹. -1 .

[0025] Beneficial effects of this invention:

[0026] Because the aluminum in the Y-type molecular sieve framework is relatively low and dispersed, fewer secondary pores are formed after dealumination, and these secondary pores exist in isolation, making it difficult for them to merge together. Therefore, only one type of mesopore is generated after hydrothermal treatment. Furthermore, during hydrothermal treatment, the Y-type molecular sieve with a high silica-to-alumina ratio maintains a high relative crystallinity. A higher silica-to-alumina ratio in the framework is beneficial to the structural stability of the Y-type molecular sieve. Nano-SAPO-34 molecular sieves have multi-level channels, which synergize with the mesopores of the Y-type molecular sieve to enhance the diffusion capacity of the catalyst. After hydrothermal treatment, more suitable surface acidic sites are obtained to reduce coking. Microwave treatment of the channels further reduces the acid strength of the catalyst, modifying its surface acidity and modifying the channel structure to achieve desiliconization and aluminum replenishment effects. This makes the molecular sieve catalyst more suitable for processing the aromatic feedstock of this invention, further improving the catalyst's stability and activity, and extending its lifespan. Olefins and aromatics undergo chelation and alkylation reactions on the modified molecular sieve catalyst to generate high-boiling-point compounds, thereby removing trace amounts of olefins from reformed aromatics. Using this catalyst can effectively reduce olefins in reformed oil, replace bleaching clay, and achieve long-term environmentally friendly operation of the unit.

[0027] The catalyst prepared by this invention is inexpensive, has a simple and efficient catalytic reaction system, good stability, and mild reaction conditions. After 72 hours of reaction, the bromine index of the product is below 300 mgBr / 100g, the aromatic loss rate is small, and the changes in the amount of toluene components at the inlet and outlet are minimal. The catalyst performance meets the requirements for olefin removal from reformate. Detailed Implementation

[0028] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0029] raw material:

[0030] HY Molecular Sieves: Si / Aluminum Ratio 8.0 Suzhou Beike Nanotechnology

[0031] HY Molecular Sieves: Si / Aluminum Ratio 7.0 Suzhou Beike Nanotechnology

[0032] HY Molecular Sieves: Silicon-to-Aluminum Ratio 8.5 (Suzhou Beike Nanotechnology)

[0033] SAPO-34 molecular sieve: 2~8μm, Dalian Zhuoran Environmental Protection Technology Co., Ltd.

[0034] Citric acid: CP, produced by Jiangsu Aofu Biotechnology

[0035] Sesbania powder: Beijing Zhongxi Huada Technology Co., Ltd.

[0036] Al2O3: Particle size 3~4μm, Chenlong Environmental Protection Co., Ltd.

[0037] Example 1

[0038] 0.808g of guar gum powder and 3.232g of citric acid were added to 80g of HY molecular sieve with a silicon-to-aluminum ratio of 8.0 and 0.8g of nano-SAPO-34 molecular sieve, and ground and mixed thoroughly. 50ml of 3% dilute nitric acid was added to 16.968g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 20℃ for 8 hours, then dried at 90℃ for 8 hours, and then calcined at 400℃ for 2.5 hours, followed by natural cooling to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 600℃, 5MPa, for 3 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 30℃ for 3 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2mm lengths and labeled CAT1.

[0039] Example 2

[0040] 1.5g of guar gum powder and 2.2g of citric acid were added to 70g of HY molecular sieve with a silicon-to-aluminum ratio of 7.0 and 2g of nano-SAPO-34 molecular sieve, and ground and mixed thoroughly. 98.5mL of 3% dilute nitric acid was added to 48.5g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 25℃ for 10 hours, then dried at 100℃ for 10 hours, then calcined at 450℃ for 3 hours, and allowed to cool naturally to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 620℃ and 6MPa for 4 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 40℃ for 4 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2mm lengths and labeled CAT2.

[0041] Example 3

[0042] 2.5 g of guar gum powder and 2.3 g of citric acid were added to 100 g of HY molecular sieve with a silicon-to-aluminum ratio of 8.0 and 4 g of nano-SAPO-34 molecular sieve, and the mixture was ground and mixed evenly. 163 mL of 3% dilute nitric acid was added to 54.4 g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 25℃ for 12 hours, then dried at 110℃ for 12 hours, and then calcined at 500℃ for 4 hours, followed by natural cooling to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 650℃ and 6 MPa for 4 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 40℃ for 4 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2 mm lengths and labeled CAT3.

[0043] Example 4

[0044] 2.52g of guar gum powder and 1.68g of citric acid were added to 80g of HY molecular sieve with a silicon-to-aluminum ratio of 8.5 and 4g of nano-SAPO-34 molecular sieve, and ground and mixed thoroughly. 132mL of 3% dilute nitric acid was added to 44.1g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 28℃ for 12 hours, then dried at 110℃ for 12 hours, then calcined at 550℃ for 4.5 hours, and allowed to cool naturally to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 650℃ and 6MPa for 4 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 40℃ for 4 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2mm lengths and labeled CAT4.

[0045] Example 5

[0046] 1.575g of guar gum powder and 6.3g of citric acid were added to 150g of HY molecular sieve with a silicon-to-aluminum ratio of 7.0 and 7.5g of nano-SAPO-34 molecular sieve, and ground and mixed thoroughly. 268.5mL of 3% dilute nitric acid was added to 50g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 30℃ for 12 hours, then dried at 120℃ for 14 hours, and then calcined at 600℃ for 6 hours, followed by natural cooling to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 700℃ and 7MPa for 5 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 40℃ for 5 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2mm lengths and labeled CAT5.

[0047] Example 6

[0048] 0.832g of guar gum powder and 2.5g of citric acid were added to 80g of HY molecular sieve with a silicon-to-aluminum ratio of 8.0 and 3.2g of nano-SAPO-34 molecular sieve, and ground and mixed thoroughly. 179mL of 3% dilute nitric acid was added to 63g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 30℃ for 12 hours, then dried at 120℃ for 14 hours, and then calcined at 600℃ for 3 hours, followed by natural cooling to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 650℃, 7MPa, for 5 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 50℃ for 4 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2mm lengths and labeled as CAT6.

[0049] Example 7

[0050] 1.23g of guar gum powder and 1.23g of citric acid were added to 60g of HY molecular sieve with a silicon-to-aluminum ratio of 8.5 and 1.2g of nano-SAPO-34 molecular sieve, and ground and mixed thoroughly. 65mL of 3% dilute nitric acid was added to 12.73g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 20℃ for 12 hours, then dried at 110℃ for 12 hours, then calcined at 650℃ for 2.5 hours, and allowed to cool naturally to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 650℃ and 6MPa for 4 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 40℃ for 5 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2mm lengths and labeled CAT7.

[0051] Comparative Example 1

[0052] Comparative Example 1 was prepared according to the method disclosed in CN102008976A:

[0053] Add 43g of MCM-22 molecular sieve (silicon-to-aluminum ratio 8.0, rare earth content 5.0%, produced by Suzhou Beike Nanotechnology) and 45g of boehmite (calculated as Al2O3, produced by Chenlong Environmental Protection Co., Ltd.) to 101g of ReUSY molecular sieve (silicon-to-aluminum ratio 8.0, rare earth content 5.0%). Mix well. Slowly add 155mL of 3% dilute nitric acid solution to the mixture and knead into a ball. Extrude the ball into strips using a φ1.6 cylindrical perforated plate. Dry the strips at 110℃ for 12 hours, then calcine at 400℃ for 8 hours and cool to room temperature. The finished catalyst is prepared. Cut the treated strip catalyst into 2mm lengths and label the catalyst as CAT8.

[0054] Comparative Example 2

[0055] 2.52 g of guar gum powder and 1.68 g of citric acid were added to 80 g of HY molecular sieve with a silicon-to-aluminum ratio of 8.5 and ground and mixed thoroughly. 128 mL of 3% dilute nitric acid was added to 44.1 g of Al2O3 to form a gel. The mixed powder was then added to the gel to moisten and knead, and extruded into strips using a φ2 clover-shaped perforated plate. The strips were first dried at 28℃ for 12 hours, then dried at 110℃ for 12 hours, and then calcined at 550℃ for 4.5 hours, followed by natural cooling to room temperature. The formed catalyst was then subjected to hydrothermal treatment at 650℃ and 6 MPa for 4 hours to desilicate, adjusting the pore structure and surface acidity of the catalyst. The pores were then cleaned by microwave treatment at 40℃ for 4 hours to prepare the finished catalyst. The treated strip catalyst was cut into 2 mm lengths and labeled CAT9.

[0056] Evaluation and analysis methods:

[0057] The performance evaluation of the catalysts for deolefination was conducted on a self-built 10 mL continuous fixed-bed evaluation apparatus. 10.0 mL of each catalyst grade was weighed and loaded into a continuous flow fixed-bed reactor. Ceramic balls were placed at both ends of the reactor. The reaction temperature was controlled at 163 °C, the reaction pressure at 2.0 MPa, and the mass hourly space velocity at 20 h⁻¹. -1 Under these conditions, the deolefin liquid product was sampled and analyzed at different time intervals after the isothermal reaction.

[0058] The feedstock, reformate, was supplied by the catalytic cracking unit of Daqing Petrochemical Refinery. The feedstock had a bromine index of 860 mgBr / 100mL and a density of 0.713 g / mL. After a certain reaction time, samples of the product were taken to determine the bromine index. The results are listed below. A bromine index close to or reaching 200 mgBr / 100mL was used as the criterion for catalyst deactivation.

[0059] Table 1. Comparison of bromine index (mgBr / 100mL) of different catalyst products

[0060]

[0061] As shown in Table 1, the initial activity of the catalyst prepared in this invention is higher than that of commercially available molecular sieve catalysts, and the lifespan of the two catalysts, CAT3 and CAT4, is also significantly extended.

[0062] Table 2. Distribution of Quality Composition of Reformate Feedstock and Products

[0063]

[0064] As shown in Table 2, the composition of the aromatic products treated with molecular sieve catalysts remained basically unchanged. The aromatic content increased slightly after deolefination, and the change in toluene content before and after deolefination was very small (≥0.01%). This indicates that the deolefination molecular sieve catalyst prepared in this invention can meet the requirements for the quality of deolefination of the product.

[0065] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing a catalyst for removing trace amounts of olefins from reformate, characterized in that, Includes the following steps: (1) Mix Y-type molecular sieve, SAPO-34 molecular sieve, pore expander and extrusion aid evenly to form a mixed powder; (2) Alumina is mixed into a gel with an inorganic acid solution. The mixed powder from step (1) is added to the gel for mixing, wetting, and kneading until uniform. Then it is shaped, dried, and calcined to obtain the shaped catalyst. (3) The shaped catalyst is subjected to hydrothermal treatment and microwave treatment to obtain the finished catalyst; The mass ratio of SAPO-34 molecular sieve to Y molecular sieve is 1~5:100; The silicon-to-aluminum ratio of the Y-type molecular sieve is 7.0~8.5; The hydrothermal treatment conditions in step (3) are 600~700℃, 5~7Mpa, and 3~5 hours of hydrothermal treatment; In step (3), the microwave treatment conditions are 30~50℃ microwave cleaning for 3~5 hours.

2. The method for preparing the catalyst for removing trace amounts of olefins from reformate according to claim 1, characterized in that, The pore-expanding agent is guar gum powder, the extrusion aid is citric acid, the guar gum powder is 1-3 wt% of the total mass of Y-type molecular sieve and SAPO-34 molecular sieve, and the citric acid is 2-4 wt% of the total mass of Y-type molecular sieve and SAPO-34 molecular sieve.

3. The method for preparing the catalyst for removing trace amounts of olefins from reformate according to claim 1, characterized in that, The mass ratio of alumina to mixed powder is 0.2~0.75:1, and the mass ratio of the amount of inorganic acid solution to the total amount of mixed powder and alumina is 1:0.8~2.

0.

4. The method for preparing the catalyst for removing trace amounts of olefins from reformate according to claim 1, characterized in that, In step (2), the drying process involves first air-drying at 18~30℃, and then drying at 90~120℃ for 8~16 hours. The calcination process involves calcining at 400~650℃ for 2.5~6.5 hours.

5. The application of the catalyst prepared by the method according to any one of claims 1 to 4 in the removal of trace olefins from reformate, characterized in that, The bromine index in the reformed oil is 800~1200 mgBr / 100g, the reaction temperature is 130℃~220℃, the reaction pressure is 1.0~2.0MPa, and the reaction space velocity is 0.5~20 h⁻¹. -1 .

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