Pentene isomerization catalyst capable of regulating and controlling position of isopentene double bond as well as preparation method and application of pentene isomerization catalyst
By introducing metal oxides into the molecular sieve catalyst to regulate the double bond position of isoprene, the problems of long process flow and high energy consumption in the existing technology are solved, and the regulating content of 2M1B and 2M2B in isoprene is achieved, and the product is improved Economic value and process efficiency.
Patent Information
- Application Number
- CN202411204869.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-08-30
- Publication Date
- 2024-12-10
AI Technical Summary
In the prior art, the mixed raw materials with n-pentene as the main component control the transfer of double bond positions during isomerization by a one-step method, making it difficult to regulate the relative content distribution of 2M1B and 2M2B in the product isoprene, resulting in a long process flow. The separation energy consumption is high and lacks economicality.
The molecular sieve catalyst is used as a support to introduce metal oxides to prepare a pentyle isomerization catalyst that can regulate the double bond position of isoprene. By introducing metal oxides on the basis of not destroying the molecular sieve structure, the double bond position of isoprene isomerization catalyst is prepared. Simplify the process flow and reduce energy consumption.
It has achieved the regulation of the relative content distribution of 2M1B and 2M2B in the product under the premise of ensuring the conversion rate of n-pentene and isoprene yields, which can improve the economic value of the product, shorten the process flow, save energy, and have environmental advantages.
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Figure CN119098213A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a pentene isomerization catalyst capable of regulating the double bond position of isopentene, a preparation method and application thereof, and belongs to the technical field of catalysts in energy chemical industry. Background Art
[0002] As a fine chemical intermediate, isopentene is widely used in the chemical industry and can be used to produce chemical products such as flavor enhancers, galaxol, crop protection agents, and ultraviolet absorbers. In recent years, many downstream products of isopentene have developed rapidly, and the demand for isopentene at home and abroad has continued to increase. With the rapid increase in the production capacity of petroleum catalytic cracking, naphtha cracking to produce ethylene, and coal / methanol to olefins (MTO) in my country, the availability of C5 resources has also continued to increase. Converting C5 resources into isopentene with higher reaction activity and then producing high value-added chemicals has become a focus of attention.
[0003] At present, the production method of isopentene is mainly ether cracking method, which is to use isopentene in C5 resources and methanol to carry out etherification reaction to produce methyl tert-amyl ether, and then use the methyl tert-amyl ether after separation and purification to produce high-purity isopentene through high-temperature cracking technology. C5 resources contain a large amount of n-pentene, especially the n-pentene content in MTO by-product C5 is as high as nearly 30wt%. Most of the n-pentene in C5 resources is used as cheap fuel and cannot be fully utilized, resulting in a waste of resources. Using the pentene isomerization process to convert the n-pentene in C5 resources into isopentene can increase the isopentene production capacity, make full use of C5 resources, and improve the economic benefits of petroleum / coal chemical enterprises.
[0004] In the existing industrial application technology, the catalysts commonly used for the isomerization reaction of pentene are alumina catalysts and molecular sieve catalysts. The acid strength of alumina itself is weak, and the catalytic effect is not ideal. It needs other metal elements to modify it to improve the acid strength and thus improve its reaction performance. However, during the reaction, the modified metal atoms or oxides are prone to fall off and loss, which leads to a decrease in catalyst activity. Compared with alumina, molecular sieve catalysts have better low-carbon olefin isomerization reaction performance. CN113122313A discloses a method for isomerization of olefins, wherein the catalyst carrier used is ZSM-35 molecular sieve, and ZSM-35 is modified by metal salt solution, and then an isomerization catalyst is obtained by acid treatment, ammonium exchange, etc., and the yield of isopentene can reach about 50%. CN116490483A uses small microcrystalline ferrous alkali zeolite as a catalyst for the isomerization of butene, and it is found that compared with conventional catalysts, the isomerization rate increases by 5 to 20%, the life cycle of the catalyst is at least 75% longer than that of conventional catalysts, and the yield of isobutylene can be stabilized at 45% for a long time.
[0005] Isoamylene has three isomers: 2-methyl-1-butene (2M1B), 2-methyl-2-butene (2M2B) and 3-methyl-1-butene (3M1B). The isopentene in existing industrial products is mainly a mixture of 2M1B and 2M2B. The relative content of the two determines the application scenarios and economic value of isopentene. At present, the main production route of industrial isopentene is divided into two steps: first, the by-products of the naphtha refining process are separated to obtain a mixed C5, and the mixed C5 enriched in n-pentene is obtained through skeletal isomerization reaction to produce a mixture of 2M1B and 2M2B (the isomerization process is as follows: Figure 1 As shown). However, due to the isomeric characteristics of 2M1B and 2M2B, the continuous industrial production of isopentene products can only obtain a mixture of components with a relatively high content by sacrificing high energy consumption (multi-stage distillation separation). Regarding the technical development of such mixed isopentene products, more research work is focused on the development of isomerization catalysts with high n-pentene conversion capacity. For example, CN 103566975A discloses a method for improving isomer selectivity by modifying ZSM-35 molecular sieves with polyols. After modification with propylene glycol, isopentene selectivity and yield are increased. The isopentene selectivity can reach about 71%, and the yield can reach 60%.
[0006] Due to the different positions of the double bonds of 2M1B and 2M2B in isopentene, their respective application scenarios and product economics are different, and researchers have gradually begun to pay attention to the double bond isomerization transformation between 2M1B and 2M2B isomers (see Figure 2 ), such as CN101723787B discloses a method for increasing the content of 2-methyl-2-butene in isopentene, wherein water is added to the raw material isopentene, and then the raw material is passed through a fixed bed catalyst bed composed of a sulfonic acid cation exchange resin for an isomerization reaction, so that the 2-methyl-1-butene in the isopentene can be converted into 2-methyl-2-butene.
[0007] In summary, the current technical development of isopentene products is mostly centered around the isomerization of n-pentene as a raw material to produce mixed isopentene with a higher yield and combined with a high-energy consumption distillation separation process; on the above basis, some researchers will separate the mixed isopentene containing 2M1B and 2M2B and then achieve double bond isomerization between isomers to obtain an isopentene mixed product with a relatively high content of components. The above-mentioned process method from n-pentene to isopentene products with a relatively high content of components has a long process flow, high separation energy consumption, and the unit product consumption is not economical. However, for mixed raw materials with n-pentene as the main component, there is no relevant report on the isomerization technology that controls the transfer of double bond positions during the isomerization process by a one-step method to regulate the distribution of 2M1B and 2M2B products in the product isopentene. If the relative content of 2M1B and 2M2B in the n-pentene isomerization product can be regulated and distributed in one step while ensuring the n-pentene conversion rate and isopentene yield, it will not only improve the economic value of the product, but also shorten the process flow, save energy, protect the environment, and be conducive to sustainable development. Summary of the invention
[0008] In order to overcome the deficiencies of the prior art, for a mixed raw material with n-pentene as the main component, in order to make up for the blank of the isomerization technology of controlling the transfer of the double bond position in the isomerization process by a one-step method, and then regulating the distribution of 2M1B and 2M2B products in the product isopentene, the present invention provides a pentene isomerization catalyst capable of regulating the double bond position of isopentene and a preparation method thereof. The present invention uses a molecular sieve catalyst as a carrier, introduces a metal oxide on the basis of not destroying the molecular sieve structure, obtains a pentene isomerization catalyst capable of regulating the double bond position of isopentene during the isomerization process, has a simple process, saves time, has mild reaction conditions, and shortens the pentene isomerization reaction process.
[0009] A catalyst for isomerization of pentene capable of regulating the position of double bonds of isopentene, the catalyst comprising a molecular sieve and a metal oxide; the metal oxide accounts for 0.5-10 wt% of the catalyst mass; the molecular sieve particles in the catalyst have a size of 1-2 μm and exist in the form of aggregates; the metal oxide particles have a size of 1-5 nm, preferably 1.5-3.0 nm, and are uniformly distributed on the outer surface of the molecular sieve to ensure that they can play a synergistic role with the molecular sieve and thus reduce the activation energy of the alkyl transfer reaction path; it is worth noting that the metal oxide will not react with the molecular sieve. The acid sites combine to form a new metal form, otherwise it is difficult to adjust the double bond position of isopentene.
[0010] The molecular sieve is a hydrogen-type molecular sieve, selected from one or more combinations of ZSM-35 molecular sieve, ZSM-22 molecular sieve, ZSM-5 molecular sieve, SAPO-11 molecular sieve, and AIPO-11 molecular sieve; preferably, the silicon-aluminum ratio of the silicon-aluminum molecular sieve in the hydrogen-type molecular sieve is 15 to 100, and the silicon-aluminum ratio of the phosphorus-aluminum molecular sieve is 0.05 to 0.3. If the Si / Al ratio of the silicon-aluminum molecular sieve is too low or the Si / Al ratio of the phosphorus-aluminum molecular sieve is high, it will lead to excessive acid and then polymerization reaction and cracking reaction, reducing the selectivity of isopentene; if the Si / Al ratio of the silicon-aluminum molecular sieve is too high or the Si / Al ratio of the phosphorus-aluminum molecular sieve is low, it will lead to insufficient number of active sites and low conversion rate of pentene.
[0011] The metal oxide is one or a combination of ZnO, MgO, CaO, NiO, CuO, Cr2O3, and CoO. In the present invention, the metal oxide is introduced into the molecular sieve catalyst, and the metal oxide accounts for 0.5-10wt% of the catalyst mass, preferably 4-8wt%, and more preferably 6wt%. Too high or too low a loading of the metal oxide will lead to a decrease in the conversion rate of pentene and the yield of isopentene. After the molecular sieve is loaded with metal oxide, the conversion rate of n-pentene and the yield of isopentene are improved, and with the increase of the metal oxide loading, the n-pentene conversion rate and the isopentene yield increase more, when the metal oxide accounts for 6% of the catalyst mass, that is, when the loading amount is increased to 6%, the n-pentene conversion rate and the isopentene yield reach the maximum value, and with the further increase of the metal loading amount, the n-pentene conversion rate and the isopentene yield decrease; after the metal oxide is loaded, the carbon deposition amount of the catalyst is significantly reduced, and with the increase of the loading amount, the carbon deposition amount is improved more obviously, and the improvement is most obvious when the loading amount is increased to 6%, and then with the increase of the metal loading amount, the change is not obvious; with the increase of the metal oxide loading amount, the ratio of the yield of 2M1B to 2M2B is larger, and the content of 2M1B in the product isopentene is increased.
[0012] The present invention also provides a method for preparing the catalyst, which comprises immersing the molecular sieve in a solution containing a metal precursor, allowing the solution to stand after ultrasonic treatment, and then drying and calcining to obtain the pentene isomerization catalyst capable of regulating the position of the isopentene double bond.
[0013] In the above method, the metal precursor solution is one or a combination of nitrate or sulfate solutions of Zn, Mg, Ca, Ni, Cu, Cr, and Co; the concentration of the metal precursor solution is 0.02-2 mol / L.
[0014] In the above method, the molecular sieve is impregnated in a solution containing a metal precursor to introduce the metal oxide into the molecular sieve catalyst, and the impregnation is one of equal volume impregnation, excess impregnation or multiple impregnations.
[0015] In the above method, the metal salt solution is slowly dripped into the molecular sieve at room temperature while stirring, then ultrasonicated at 50°C for 30-90 minutes, allowed to stand at room temperature for 12 hours, dried at 100°C-130°C for 4 hours, and finally calcined at 550°C for 4-6 hours.
[0016] The present invention also provides the use of the above catalyst in an isomerization reaction, wherein the raw material of the isomerization reaction is at least one of 2-pentene (cis), 2-pentene (trans), and 1-pentene; the reaction temperature of the isomerization reaction is 260-400°C, the reaction pressure is 0-0.5MPa, and the mass space velocity of pentene is 5-20h -1 .
[0017] The present invention provides a catalyst for adjusting the position of the double bond of isopentene in the isomerization reaction of pentene without significantly changing the yield of isopentene. The pentene isomerization catalyst capable of adjusting the position of the double bond of isopentene in the present invention can adjust the reaction path during the isomerization reaction of pentene, and adjust the relative content of 2M1B and 2M2B in one step. At the same time, the physical and chemical properties of the molecular sieve do not change significantly, and the total isopentene yield is improved. The skeletal isomerization of pentene is mainly carried out through a unimolecular reaction mechanism, which is mainly carried out through two reaction paths of methylcyclopropane and alkyl transfer. The methylcyclopropane reaction path generates two products, 2M1B and 2M2B, while the alkyl transfer reaction path only generates one product, 2M1B. Compared with the conventional pentene isomerization catalyst, the introduction of the metal oxide in the catalyst reduces the activation energy of the alkyl transfer path during the isomerization reaction, thereby improving the yield of 2M1B, and simultaneously realizing the regulation of the double bond position of isopentene during the isomerization reaction, reducing the refining section of isopentene, shortening the process flow, and reducing the waste of energy. In the invention, the conversion rate of n-pentene is 50-100%, the yield of isopentene is 40-95%, and the relative content ratio of 2-methyl-1-butene to 2-methyl-2-butene in the product can be adjusted within the range of 0.2-0.75. BRIEF DESCRIPTION OF THE DRAWINGS
[0018] Figure 1 It is the skeletal isomerization process of n-pentene.
[0019] Figure 2 It is the mutual conversion process between 2M1B and 2M2B.
[0020] Figure 3 This is the XRD diagram of Zn / ZSM-22 used in the present invention.
[0021] Figure 4 This is a scanning electron microscope image of Zn / ZSM-22 used in the present invention.
[0022] Figure 5It is a reaction performance diagram of the Zn / ZSM-22 catalyst of the present invention.
[0023] Figure 6 It is the selectivity and relative content of 2M1B and 2M2B of the Zn / ZSM-22 catalyst of the present invention.
[0024] Figure 7 TEM images of Zn / ZSM-22 prepared in Example 2, Example 3, and Example 4. DETAILED DESCRIPTION
[0025] For the convenience of understanding the content of the present invention, the present invention now lists the following embodiments. The embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention. Because the present invention can also be described and explained by other schemes that do not depart from the technical features of the present invention, all changes within the scope of the present invention or equivalent inventions should belong to the protection scope of the present invention. The present invention is further described below in conjunction with embodiments and comparative examples.
[0026] Example 1
[0027] Dry the ZSM-22 molecular sieve, take 4g of the dried ZSM-22 molecular sieve in a beaker, prepare a zinc nitrate solution with a concentration of 0.04mol / L, and add 6g of zinc nitrate solution to 4g of the molecular sieve while stirring. At this time, the ZnO content is 0.5wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the sealing is allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the position of the double bond of isopentene, named 0.5wt% Zn / ZSM-22. Fix 0.5wt% Zn / ZSM-22 in a fixed bed reactor, and set the temperature of the fixed bed reactor to 350℃. After the temperature of the reactor is stable, use a high-pressure metering pump to pass 2-pentene into the reactor at a constant rate. The reaction pressure is normal pressure and the mass space velocity is 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 The calculated conversion rate of 2-pentene was 80.2%, the yield of isopentene was 64.4%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.38, and the carbon deposit amount after 2 hours was 2.75% of the total mass of the catalyst.
[0028] Example 2
[0029] Dry the ZSM-22 molecular sieve, take 4g of the dried ZSM-22 molecular sieve in a beaker, prepare a zinc nitrate solution with a concentration of 0.16mol / L, and add 6g of zinc nitrate solution to the 4g molecular sieve while stirring. At this time, the ZnO content is 2wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the sealing is allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the position of the double bond of isopentene, named 2wt% Zn / ZSM-22. 2wt% Zn / ZSM-22 is fixed in a fixed bed reactor, and the temperature of the fixed bed reactor is set to 350℃. After the temperature of the reactor is stable, 2-pentene is passed into the reactor at a constant rate using a high-pressure metering pump. The reaction pressure is normal pressure and the mass space velocity is 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 The calculated conversion rate of 2-pentene was 80.2%, the yield of isopentene was 64.4%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.38, and the carbon deposit amount after 2 hours was 2.75% of the total mass of the catalyst.
[0030] Example 3
[0031] Dry the ZSM-22 molecular sieve, take 4g of the dried ZSM-22 molecular sieve in a beaker, prepare a zinc nitrate solution with a concentration of 0.32mol / L, and add 6g of zinc nitrate solution to the 4g molecular sieve while stirring. At this time, the ZnO content is 4wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the sealing is allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the position of the double bond of isopentene, named 4wt% Zn / ZSM-22. Fix 4wt% Zn / ZSM-22 in a fixed bed reactor, and set the temperature of the fixed bed reactor to 350℃. After the temperature of the reactor is stable, use a high-pressure metering pump to pass 2-pentene into the reactor at a constant rate. The reaction pressure is normal pressure and the mass space velocity is 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 The calculated conversion rate of 2-pentene was 83.3%, the yield of isopentene was 71.2%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.46, and the carbon deposit amount after 2 hours was 1.76% of the total mass of the catalyst.
[0032] Example 4
[0033] Dry the ZSM-22 molecular sieve, take 4g of the dried ZSM-22 molecular sieve in a beaker, prepare a zinc nitrate solution with a concentration of 0.49mol / L, and add 6g of the zinc nitrate solution to the 4g molecular sieve while stirring. At this time, the ZnO content is 6wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the sealing is allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the position of the double bond of isopentene, named 6wt% Zn / ZSM-22. Fix 6wt% Zn / ZSM-22 in a fixed bed reactor, and set the temperature of the fixed bed reactor to 350℃. After the temperature of the reactor is stable, use a high-pressure metering pump to pass 2-pentene into the reactor at a constant rate. The reaction pressure is normal pressure and the mass space velocity is 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 86.2%, the isopentene yield was 76.2%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.54, and the carbon deposit after 2h was 1.23% of the total mass of the catalyst.
[0034] Example 5
[0035] Dry the ZSM-22 molecular sieve, take 4g of the dried ZSM-22 molecular sieve in a beaker, prepare a zinc nitrate solution with a concentration of 0.66mol / L, and add 6g of zinc nitrate solution to the 4g molecular sieve while stirring. At this time, the ZnO content is 8wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the sealing is allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the double bond position of isopentene, named 8wt% Zn / ZSM-22. 8wt% Zn / ZSM-22 is fixed in a fixed bed reactor, and the temperature of the fixed bed reactor is set to 350℃. After the temperature of the reactor is stable, 2-pentene is passed into the reactor at a constant rate using a high-pressure metering pump. The reaction pressure is normal pressure and the mass space velocity is 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 83.2%, the isopentene yield was 72.0%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.50, and the carbon deposit after 2h was 1.15% of the total catalyst mass.
[0036] Example 6
[0037] Dry the ZSM-22 molecular sieve, take 4g of the dried ZSM-22 molecular sieve in a beaker, prepare a zinc nitrate solution with a concentration of 0.82mol / L, and add 6g of zinc nitrate solution to 4g of the molecular sieve while stirring. At this time, the ZnO content is 10wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the mixture is sealed and allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the position of the double bond of isopentene, named 10wt% Zn / ZSM-22. 10wt% Zn / ZSM-22 is fixed in a fixed bed reactor, and the temperature of the fixed bed reactor is set to 350℃. After the temperature of the reactor is stable, 2-pentene is passed into the reactor at a constant rate using a high-pressure metering pump. The reaction pressure is normal pressure, and the mass space velocity is 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 81.5%, the isopentene yield was 69.6%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.48, and the carbon deposit after 2h was 1.20% of the total mass of the catalyst.
[0038] Comparative Example 1
[0039] The ZSM-22 molecular sieve was dried to obtain a catalyst sample named ZSM-22. ZSM-22 was fixed in a fixed bed reactor, and the temperature of the fixed bed reactor was set to 350°C. After the reactor temperature stabilized, 2-pentene was introduced into the reactor at a constant rate using a high-pressure metering pump. The reaction pressure was normal pressure, and the mass space velocity was 15h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 82.5%, the isopentene yield was 67.2%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.31, and the carbon deposit after 2h was 3.55% of the total catalyst mass.
[0040] Depend on Figure 3 and Figure 4 It can be seen that the introduction of metals has no significant effect on the morphology of the molecular sieve. The particle size of the molecular sieve is about 1-2 μm and exists in the form of aggregates. Figure 5It can be seen that after the introduction of metal oxides, the conversion rate of pentene and the yield of isopentene both showed a trend of first increasing and then decreasing with the increase of the loading amount. The introduction of metal oxides can reduce the activation energy of pentene isomerization or directly catalyze the isomerization reaction of pentene, thereby increasing the conversion rate of pentene; while when the loading amount of metal oxides is too high, the conversion rate of pentene shows a downward trend. A high loading amount of metal oxides will make its particles larger, reduce its dispersion and thus lead to a decrease in reaction performance. Figure 6 It was concluded that at lower metal oxide loadings, the selectivity of 2M1B gradually increased while the selectivity of 2M2B did not change significantly. The introduction of metals can promote the formation of 2M1B; while in the case of excessively high metal loadings, the selectivity of 2M1B decreased. When the metal oxide loading was too high, the metal oxide particles were larger in size and poorly dispersed, making it difficult to achieve optimal catalytic performance. Figure 7 TEM images of Zn / ZSM-22 prepared in Example 2 (a), Example 3 (b), and Example 4 (c), respectively. Means Represents the average particle size of ZnO. It can be seen that the metal oxides are evenly distributed on the outer surface of the molecular sieve. With the increase of the metal oxide loading, its particle size continues to increase and the degree of aggregation increases, which leads to a decrease in catalytic performance due to a higher metal oxide loading.
[0041] Example 7
[0042] Dry the SAPO-11 molecular sieve, take 4g of the dried SAPO-11 molecular sieve in a beaker, prepare a magnesium nitrate solution with a concentration of 0.33mol / L, and add 6g of the magnesium nitrate solution to the 4g molecular sieve while stirring. At this time, the MgO content is 2wt%. Ultrasonic treatment is carried out at 50℃ for 30min, and the mixture is sealed and allowed to stand at room temperature for 12h. Then, the mixture is placed in a 120℃ oven for drying for 4h, and calcined at 550℃ for 4h. After grinding, a pentene isomerization catalyst capable of regulating the position of the double bond of isopentene is obtained, which is named 2wt% Mg / SAPO-11. 2wt% Mg / SAPO-11 is fixed in a fixed bed reactor, and the temperature of the fixed bed reactor is set to 380℃. After the temperature of the reactor is stable, a high-pressure metering pump is used to pass 2-pentene into the reactor at a constant rate. The reaction pressure is normal pressure, and the mass space velocity is 8h. -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 76.2%, the isopentene yield was 55.9%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.37, and the carbon deposit after 2h was 2.71% of the total mass of the catalyst.
[0043] Example 8
[0044] Dry the SAPO-11 molecular sieve, take 4g of the dried SAPO-11 molecular sieve in a beaker, prepare a magnesium nitrate solution with a concentration of 0.67mol / L, and add 6g of the magnesium nitrate solution dropwise to the 4g molecular sieve while stirring. At this time, the MgO content is 4wt%, ultrasonic treatment is carried out at 50℃ for 30min, and the mixture is sealed and allowed to stand at room temperature for 12h, and then placed in a 120℃ oven for drying for 4h, calcined at 550℃ for 4h, and ground to obtain a pentene isomerization catalyst that can adjust the position of the double bond of isopentene, named 4wt%Mg / SAPO-11. Fix 4wt%Mg / SAPO-11 in a fixed bed reactor, and set the temperature of the fixed bed reactor to 380℃. After the temperature of the reactor is stable, use a high-pressure metering pump to pass 2-pentene into the reactor at a constant rate. The reaction pressure is normal pressure, and the mass space velocity is 8h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 82.3%, the isopentene yield was 67.9%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.52, and the carbon deposit after 2h was 2.35% of the total catalyst mass.
[0045] Example 9
[0046] Dry the SAPO-11 molecular sieve, take 4g of the dried SAPO-11 molecular sieve in a beaker, prepare a magnesium nitrate solution with a concentration of 1mol / L, and add 6g of the magnesium nitrate solution to the 4g molecular sieve while stirring. At this time, the MgO content is 6wt%. Ultrasonic treatment is carried out at 50℃ for 30min, and the mixture is sealed and allowed to stand at room temperature for 12h. Then, the mixture is placed in a 120℃ oven for drying for 4h, and calcined at 550℃ for 4h. After grinding, a pentene isomerization catalyst capable of regulating the position of the double bond of isopentene is obtained, which is named 6wt%Mg / SAPO-11. 6wt%Mg / SAPO-11 is fixed in a fixed bed reactor, and the temperature of the fixed bed reactor is set to 380℃. After the temperature of the reactor is stable, a high-pressure metering pump is used to pass 2-pentene into the reactor at a constant rate. The reaction pressure is normal pressure, and the mass space velocity is 8h. -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 82.2%, the isopentene yield was 70.2%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.64, and the carbon deposit after 2h was 1.96% of the total catalyst mass.
[0047] Comparative Example 2
[0048] The SAPO-11 molecular sieve was dried to obtain a catalyst sample, named SAPO-11. SAPO-11 was fixed in a fixed bed reactor, and the temperature of the fixed bed reactor was set to 380°C. After the reactor temperature stabilized, 2-pentene was introduced into the reactor at a constant rate using a high-pressure metering pump. The reaction pressure was normal pressure, and the mass space velocity was 8h -1 , carrier gas is N2, carrier gas space velocity is 3600h -1 , reaction time 30min. The calculated 2-pentene conversion was 73.5%, the isopentene yield was 50.3%, the ratio of 2M1B yield to 2M2B yield (2M1B / 2M2B) was 0.31, and the carbon deposit after 2h was 3.32% of the total catalyst mass.
Claims
1. A pentene isomerization catalyst capable of regulating the position of the double bond of isopentene, characterized in that: The catalyst consists of molecular sieve and metal oxide; the metal oxide accounts for 0.5-10wt% of the catalyst mass; the molecular sieve particles in the catalyst have a size of 1-2μm and exist in the form of aggregates, and the metal oxide particles have a size of 1-5nm and are evenly distributed on the outer surface of the molecular sieve.
2. The pentene isomerization catalyst capable of regulating the double bond position of isopentene according to claim 1, characterized in that: The particle size of the metal oxide is 1.5-3.0 nm.
3. The pentene isomerization catalyst capable of regulating the double bond position of isopentene according to claim 1, characterized in that: The molecular sieve is a hydrogen-type molecular sieve selected from one or more combinations of ZSM-35 molecular sieve, ZSM-22 molecular sieve, ZSM-5 molecular sieve, SAPO-11 molecular sieve, and AIPO-11 molecular sieve.
4. The pentene isomerization catalyst capable of regulating the double bond position of isopentene according to claim 3, characterized in that: The silicon-aluminum ratio of the silicon-aluminum molecular sieve in the hydrogen-type molecular sieve is 15 to 100; the silicon-aluminum ratio of the phosphorus-aluminum molecular sieve in the hydrogen-type molecular sieve is 0.05 to 0.
3.
5. The pentene isomerization catalyst capable of regulating the double bond position of isopentene according to claim 1, characterized in that: The metal oxide is one or a combination of ZnO, MgO, CaO, NiO, CuO, Cr2O3, and CoO.
6. The pentene isomerization catalyst capable of regulating the double bond position of isopentene according to claim 1, characterized in that: The metal oxide accounts for 4-8 wt% of the catalyst mass; more preferably 6 wt%.
7. A method for preparing a pentene isomerization catalyst capable of regulating the position of isopentene double bonds according to any one of claims 1 to 6, characterized in that: The catalyst is obtained by impregnating the molecular sieve into a metal precursor solution, allowing it to stand after ultrasonic treatment, and then drying and calcining.
8. The method according to claim 7, characterized in that The metal precursor solution is one or a combination of nitrate or sulfate solutions of Zn, Mg, Ca, Ni, Cu, Cr, and Co; the concentration of the metal precursor solution is 0.02-2 mol / L; the impregnation is one of equal volume impregnation, excess impregnation, or multiple impregnations.
9. The method according to claim 7, characterized in that: The metal precursor solution is slowly dripped into the molecular sieve at room temperature while stirring, then ultrasonicated at 50°C for 30-90 minutes, allowed to stand at room temperature for 12 hours, dried at 100°C-130°C for 4 hours, and finally calcined at 550°C for 4-6 hours.
10. Use of the pentene isomerization catalyst capable of regulating the double bond position of isopentene according to any one of claims 1 to 6 in an isomerization reaction, characterized in that: The raw material of the isomerization reaction is at least one of 2-pentene (cis), 2-pentene (trans), and 1-pentene; the isomerization reaction temperature is 260-400°C, the reaction pressure is 0-0.5MPa, and the mass space velocity of pentene is 5-20h -1 The conversion rate of n-pentene is 50-100%, the yield of isopentene is 40-95%, and the relative content ratio of 2-methyl-1-butene to 2-methyl-2-butene in the product can be adjusted within the range of 0.2-0.75.