Method for preparing 2-methoxyl olefin, metal organic framework material and preparation method of metal organic framework material

Abstract

The invention relates to the field of metal organic framework materials, and discloses a method for preparing 2-methoxyl olefin, a metal organic framework material and a preparation method of the metal organic framework material. The method comprises the following steps: carrying out cracking reaction on 2, 2-dimethoxy alkane in the presence of a catalyst; wherein the catalyst is a metal organic framework material, and the coordination metal M of the metal organic framework material is selected from one of Zn, Cr and Zr. The 2-methoxypropene prepared by the method provided by the invention is high in catalytic activity, the catalyst can be repeatedly used and is relatively long in service life, the catalyst and the product are easy to separate, the yield and the purity of the product are relatively high, and the synthesis cost is relatively low.

Description

Technical Field

[0001] The invention relates to the field of metal organic framework materials, and in particular to a method for preparing 2-methoxyolefin, a metal organic framework material and a preparation method thereof. Background Art

[0002] 2-Methoxypropene is active and very unstable, and it is difficult to produce industrially. However, in many synthetic drugs, 2-methoxypropene is a very important synthetic raw material, especially in the synthesis of clarithromycin, where it is a key intermediate. At the same time, 2-methoxypropene is also an important raw material for vitamins and carotene.

[0003] 2-Methoxypropylene was prepared by liquid phase cracking of 2,2-dimethoxypropane in the early stage, mostly using alkanes as solvents and sulfonic acids as catalysts. However, due to the relatively troublesome post-processing and the corrosion of industrial equipment by a large amount of sulfonic acid, this method was gradually eliminated. In 2002, Yang Shumin et al. published Fine Chemical Intermediates, 2002, 321: (20-21), diethylene glycol dimethyl ether was used as solvent, succinic anhydride, pyridine, and benzoic acid were used as catalysts to catalytically crack 2,2-dimethoxypropane at about 115°C, with a yield of 80.6% and a product purity of 98%. In addition, this process reduces the amount of diethylene glycol dimethyl ether used and protects the environment. However, due to the defects of diethylene glycol dimethyl ether, such as high price, high toxicity, high boiling point, and easy miscibility with water, further improvement is needed. The work published by Li Xiaoxi et al. in Anhui Chemical Industry, 2009, 35(6): 29-30 in 2009 was improved on this basis. Toluene was used to replace diethylene glycol xylene (14.6 mL) as solvent, and succinic anhydride (20 g), pyridine (15.6 mL), and benzoic acid (0.58 g) were used as catalysts. The yield could reach 81%, but it was still a homogeneous reaction, and the catalyst was complex and the separation of the catalyst and the product was difficult. The work of Dietrich et al. in patent application 5767325.1998-6-16 in 1998 used ZSM-5 catalyst for gas-phase catalytic cracking of 2,2-dimethoxypropane. The reaction temperature was between 280℃-340℃, and the product yield reached 83.3%, and the catalyst activity before and after the reaction hardly decreased. The advantage of this synthesis process is that the catalyst is easy to recover, and the disadvantage is that the preparation of the catalyst is relatively complicated.

[0004] At present, the production of 2-methoxypropylene still has problems such as large solvent influence under homogeneous catalysis, complex post-processing, difficult product separation, low yield and purity, inability to produce continuously, high reaction temperature and high synthesis cost. Summary of the invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and provide a method for preparing 2-methoxyolefin and a metal organic framework material and a preparation method thereof. The method provided by the present invention is used to prepare 2-methoxyolefin, and the catalytic activity is high, and the catalyst can be repeatedly used and has a long service life. The catalyst and the product are easy to separate, the yield and purity of the product are high, and the synthesis cost is low.

[0006] In order to achieve the above object, the present invention provides a method for preparing 2-methoxy olefins, which comprises: in the presence of a catalyst, causing 2,2-dimethoxy alkane to undergo a cracking reaction;

[0007] Wherein, the catalyst is a metal organic framework material, the ligand of the metal organic framework material is provided by a substance having a structure as shown in formula (1), and the coordination metal M is selected from one of Zn, Cr and Zr; in formula (1), M" includes H and an alkali metal element, and the alkali metal element is selected from Li, Na, K or Cs;

[0008]

[0009] The second aspect of the present invention provides a metal organic framework material, which is the metal organic framework material as defined in the first aspect or the partially acidified product as described in the first aspect.

[0010] The third aspect of the present invention provides a method for preparing a metal organic framework material, which is a method for preparing the partially acidified product as described in the first aspect.

[0011] By adopting the technical scheme provided by the present invention, when preparing 2-methoxy olefin, the catalytic activity is high, the reaction can be carried out at a relatively low temperature, and the yield and purity of the product are high; and a fixed bed reaction can be adopted, the separation of the product and the catalyst is simple, the catalyst can be repeatedly used and has a long service life, environmental pollution can be reduced, and the synthesis cost of the 2-methoxy olefin is significantly reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the thermogravimetric diagram of the metal organic framework material prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0013] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0014] In a first aspect, the present invention provides a method for preparing 2-methoxyolefins, the method comprising: subjecting 2,2-dimethoxyalkane to a cracking reaction in the presence of a catalyst;

[0015] Wherein, the catalyst is a metal organic framework material, the ligand of the metal organic framework material is provided by a substance having a structure as shown in formula (1), and the coordination metal M is selected from one of Zn, Cr and Zr; in formula (1), M" includes H and an alkali metal element, and the alkali metal element is selected from Li, Na, K or Cs;

[0016]

[0017] The inventor of the present invention has found in research that when the above method is adopted to prepare 2-methoxy olefin, the catalytic activity is high, the reaction can be carried out at a relatively low temperature, and the reaction can be carried out in a fixed bed, the product and the yield and purity are relatively high, the reaction product and the catalyst are separated simply, the catalyst can be repeatedly used, the service life is long, environmental pollution can be reduced, and the synthesis cost of 2-methoxy olefin is significantly reduced. When the catalyst specially limited by the present invention is used, the catalytic activity of the 2-methoxy olefin is much higher than the activity of the catalysts such as sulfonic acid, benzoic acid, ZSM-5 and acidic alumina conventionally used at present, and the synthesis efficiency of 2-methoxy olefin is greatly improved. As a very important drug intermediate, the improvement of the synthesis efficiency of 2-methoxy olefin can greatly reduce its synthesis cost, which is extremely important for the development of the pharmaceutical industry.

[0018] It can be understood that in order to obtain 2-methoxyolefin by cracking, the carbon number of 2,2-dimethoxyalkane is greater than or equal to 3, for example, it can be 2,2-dimethoxypropane, 2,2-dimethoxybutane, etc. According to a particularly preferred embodiment of the present invention, the 2,2-dimethoxyalkane is 2,2-dimethoxypropane, and the 2-methoxyolefin is 2-methoxypropylene.

[0019] It can be understood that M" includes H and alkali metal elements, which means that the catalyst contains both a structure in which M" is H and a structure in which M" is an alkali metal element.

[0020] According to the present invention, preferably, the metal organic framework material has a structure as shown in formula (2):

[0021]

[0022] As described above, it can be understood that the metal organic framework material also has a structure in which H in -SO3H in formula (2) is replaced by the above-mentioned optional metal.

[0023] According to the present invention, preferably, the metal organic framework material has an average particle size of 0.5-12 μm and a specific surface area of ​​50-1200 m 2 / g, pore volume is 1-11ml / g, and the most probable pore diameter is 0.1-9nm.

[0024] According to the present invention, preferably, the metal organic framework material has an average particle size of 1-10 μm and a specific surface area of ​​100-1100 m 2 / g, the pore volume is 3-10ml / g, and the most probable pore diameter is 2-8nm.

[0025] More preferably, the metal organic framework material has an average particle size of 2-7 μm and a specific surface area of ​​200-1000 (for example, it can be 200, 250, 300, 350, 400, 450, 500, 600, 700, 800, 900, 1000 and a range formed by any two of the above values ​​and a value within the range) m 2 / g, the pore volume is 4-9 (for example, it can be 4, 5, 6, 7, 8, 9 and the range formed by any two of the above values ​​and the value within the range) ml / g, and the most probable pore diameter is 4-6 (for example, it can be 4, 5, 6) nm.

[0026] According to the present invention, preferably, in M", the molar ratio of the alkali metal element to H is (0.001-1000):1, preferably (0.005-50):1, and more preferably (0.5-5):1. The catalyst has a benzenesulfonic acid biphenyl structure, is stable in structure, and is acidic. The acidity of the catalyst can be adjusted by adjusting the molar ratio of the alkali metal element to H to improve the catalytic effect of the cracking reaction, improve the product selectivity and conversion rate. The molar ratio of the alkali metal element to H (that is, the ratio of the sulfonate metal salt root to the sulfonate root) can generally be determined by thermogravimetry. On the thermogravimetric curve, the weight of the metal organic framework material mainly loses weight three times as the temperature increases. According to functional groups and organic common sense, the first weight loss is caused by the sulfonate root, the second weight loss is caused by the sulfonate metal salt root, and the last weight loss is caused by the complete combustion of the organic framework.

[0027] The catalyst provided by the present invention can generally exist relatively stably. The catalyst has relatively stable sulfonic acid groups, and the skeleton structure can exist stably in water and organic solvents.

[0028] According to the present invention, preferably, the cracking reaction comprises: passing a gas containing 2,2-dimethoxyalkane into a reactor loaded with a catalyst.

[0029] According to a preferred embodiment of the present invention, the reactor is a fixed bed reactor.

[0030] According to the present invention, preferably, the amount of gas containing 2,2-dimethoxyalkane introduced is such that the space velocity of 2,2-dimethoxyalkane is 3000-10000 (for example, it can be 3000, 4000, 5000, 6000, 7000, 8000, 9000, 10000 and the range formed by any two of the above values ​​and the values ​​within the range) ml / h.

[0031] According to the present invention, preferably, the gas containing 2,2-dimethoxyalkane uses an inert gas as a carrier gas, and the inert gas is selected from at least one of nitrogen, helium and argon.

[0032] According to the present invention, preferably, the conditions of the cleavage reaction include: a temperature of 30-200° C., preferably 50-150° C. (for example, it can be 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, and a range formed by any two of the above values ​​and a value within the range)° C. The method provided by the present invention can carry out the cleavage reaction at a lower temperature than the prior art, and the synthesis cost is lower.

[0033] According to the present invention, preferably, after the cracking reaction, the method further comprises: distilling the liquid phase obtained by the cracking reaction. The liquid phase obtained after the reaction generally contains 2-methoxyolefin, methanol and 2,2-dimethoxyalkane, and the 2-methoxyolefin can be fully purified by distillation. The method of the present invention can separate and purify 2-methoxyolefin in a simple manner.

[0034] According to the present invention, preferably, the distillation is carried out in a distillation tower, and the distillation temperature is 30-80° C., more preferably 50-60° C. (for example, it can be 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, and the range formed by any two of the above values ​​and the value within the range)° C. For example, vacuum distillation can be carried out at 0.1-0.5 atm.

[0035] According to the present invention, preferably, the method for preparing the catalyst comprises:

[0036] (1) in the presence of a first solvent and an organic acid, causing the compound represented by formula (3) to undergo a coordination reaction with a metal source to be coordinated;

[0037] (2) partially acidifying the product of the coordination reaction in the presence of an inorganic acid;

[0038] Wherein, in formula (3), M' is selected from Li, Na, K or Cs; the metal M in the metal source to be coordinated is selected from one of Zn, Cr and Zr;

[0039]

[0040] Here, “partial acidification” means that the alkali metal M′ is partially replaced by H, so that the partially acidified product finally obtained, wherein the position of M′ is partially still an alkali metal element and partially replaced by H.

[0041] According to the present invention, preferably, in step (1), the conditions for the coordination reaction (i.e., sintering crystallization) include: a temperature of 80-200°C, more preferably 100-150°C (for example, it can be 100, 110, 120, 130, 140, 150, and values ​​within the range formed by any two of the above values)°C; a time of 5-50h, more preferably 10-48h (for example, it can be 10, 12, 14, 16, 18, 20, 22, 24, 28, 30, 32, 36, 38, 40, 42, 44, 46, 48, and values ​​within the range formed by any two of the above values)h.

[0042] According to the present invention, preferably, in step (1), the molar ratio of the metal source to be coordinated, the compound represented by formula (3), the first solvent and the organic acid is (1-5):1:(1-30):(0.1-10), preferably (2-3):1:(2-25):(0.5-5).

[0043] According to the present invention, preferably, the metal source to be coordinated is selected from one of Zn(NO3)2, Cr(NO3)3 and ZrCl4. The above metal source to be coordinated can be used in the form of its hydrate, for example, Zn(NO3)2·8H2O, Cr(NO3)3·6H2O, etc.

[0044] According to the present invention, preferably, the first solvent is selected from at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide and N-methylpyrrolidone, more preferably N,N-dimethylformamide.

[0045] According to the present invention, preferably, in step (1), the organic acid is selected from at least one of formic acid, acetic acid and benzoic acid.

[0046] After the coordination reaction, the material can be centrifuged and filtered, and the solid obtained after filtration can be washed and dried in sequence. The centrifugal condition can be 3500-6000rpm, and the time can be 20-30min; in the washing, DMF can be used for washing 2-4 times, and then methanol can be used for washing 2-4 times, and the amount of detergent used in the washing is not particularly limited. The drying temperature can be 100-130°C, and the time can be 2-10h.

[0047] According to the present invention, preferably, in step (2), the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid, more preferably hydrochloric acid. The solid product obtained in step (1) can be mixed with an aqueous solution of the acid, and the concentration of the acid in the aqueous solution of the acid can be 0.8-8 mol / L.

[0048] According to the present invention, preferably, the conditions for partial acidification include: a temperature of 15-60°C (for example, it can be 15°C, 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C and any range formed by any two of the above values ​​and values ​​within the range), and a time of 2-36h (for example, it can be 2h, 5h, 10h, 15h, 20h, 25h, 30h, 35h, 36h and any range formed by any two of the above values ​​and values ​​within the range).

[0049] According to the present invention, preferably, the amount of the inorganic acid used is 0.01-0.99 mol per mole of the compound represented by formula (3), so that partial acidification can be achieved.

[0050] After the partial acidification is completed, the material obtained by partial acidification can be filtered, and the obtained solid can be washed with water for 2-4 times. There is no particular limitation on the amount of water used for washing.

[0051] The present invention has no particular limitation on the method for obtaining the compound represented by formula (3). Preferably, the preparation step of the compound represented by formula (3) comprises: in the presence of a second solvent and a metal halide, subjecting 4,4'-biphenyldicarboxylic acid to a substitution reaction with p-chlorobenzenesulfonate.

[0052] According to the present invention, preferably, the conditions of the substitution reaction include: temperature of 30-100° C., preferably 40-80° C.; time of 5-30 h, preferably 8-24 h.

[0053] According to the present invention, preferably, the molar ratio of 4,4'-biphenyldicarboxylic acid, p-chlorobenzenesulfonate and metal halide is 1:(0.8-1.5):(0.01-0.1).

[0054] According to the present invention, preferably, the metal halide is selected from at least one of AlCl3, RuCl3 and FeCl3.

[0055] According to the present invention, preferably, the second solvent is selected from chlorobenzene and / or dichloromethane. The amount of the second solvent is not particularly limited, for example, relative to 1g of 4,4'-biphenyldicarboxylic acid, the amount of the second solvent can be 30-50ml.

[0056] After the substitution reaction is completed, the material after the substitution reaction can be filtered, washed and dried in sequence. The washing can be firstly carried out with the same detergent as the second solvent for 2-4 times, and then washed with methanol for 2-4 times; the drying temperature can be 80-100°C and the drying time can be 5-8h.

[0057] In a second aspect, the present invention provides a metal organic framework material, which is the metal organic framework material defined in the first aspect or the partially acidified product described in the first aspect.

[0058] In a third aspect, the present invention provides a method for preparing a metal organic framework material, which is the method for preparing the partially acidified product described in the first aspect.

[0059] The present invention will be described in detail below through examples.

[0060] In the following examples, the average particle size was determined by Thermo Scientific TM The specific surface area, pore volume and most probable pore diameter were measured by Apreo scanning electron microscope, and the specific surface area, pore volume and most probable pore diameter were measured by physical adsorption instrument AntonPaar QuantaTec. In the catalyst, the molar ratio of alkali metal element and H in M" was determined by the ratio of sulfonate metal salt to sulfonate, that is, by thermogravimetry: the weight of the material mainly loses weight three times as the temperature increases, the first weight loss is caused by the sulfonate weight loss, and the second weight loss is caused by the sulfonate metal salt. Taking the metal organic framework material prepared in Example 1 as an example, Figure 1 As shown, the weight loss around 300-500°C is caused by sulfonate radicals, and the weight loss around 500-600°C is caused by sulfonate metal salt radicals.

[0061] In the following examples, the reaction tube used for the cracking reaction was 1 meter in length and 1 centimeter in inner diameter.

[0062] In the following examples, the liquid phase obtained after the reaction was distilled (50° C., reduced pressure distillation at 0.2 atm) to separate 2-methoxypropylene, methanol and 2,2-dimethoxypropane, and each substance and its corresponding content were confirmed by GC.

[0063] In the following examples, the conversion rate of 2,2-dimethoxypropane is calculated as follows: 100% - mass percentage of 2,2-dimethoxypropane in the liquid phase obtained by the reaction;

[0064] The reaction selectivity is calculated by the ratio of the sum of the amount of 2-methoxypropylene and the amount of methanol in the liquid phase obtained by the reaction to the conversion rate of 2,2-dimethoxypropane.

[0065] Example 1

[0066] (1) Preparation of acidic metal organic framework material 1, wherein the corresponding coordination metal M is Zn, and M" is H and Na.

[0067] Add 0.71 g of AlCl3, 24.20 g of 4,4'-biphenyldicarboxylic acid, 21.40 g of sodium p-chlorobenzenesulfonate and 1000 mL of chlorobenzene to the reaction bottle, carry out the substitution reaction at 50°C for 12 h, filter, wash the obtained solid three times with 100 mL of chlorobenzene, wash three times with 100 mL of methanol, and dry at 80°C for 5 h to obtain 40.7 g of white powder (wherein M' is Na).

[0068] Afterwards, Zn(NO3)2·8H2O, the compound represented by formula (3), DMF and acetic acid were subjected to coordination reaction (calcination crystallization) at a molar ratio of 2.5:1:25:5 at 100°C for 24 hours, centrifuged at 4000 rpm for 20 minutes, and then filtered. The solid was washed three times with 50 mL of DMF and three times with 50 mL of methanol, and then the solid was dried at 105°C for 5 hours to obtain a white solid.

[0069] 6 mol / L hydrochloric acid was added to the white solid in an amount such that the amount of hydrochloric acid used was 0.07 mol per mole of the compound represented by formula (3), and the mixture was acidified at 35°C for 5 hours under stirring; the solid was filtered and rinsed three times with 50 mL of water to obtain an acidified metal organic framework material (the XRD spectrum and scanning electron microscopy confirmed that the same framework structure as that in formula (2) was obtained, wherein Zn was the coordination metal). The average particle size of the obtained metal organic framework material was 5 μm, and the specific surface area was 965 m 2 / g, pore volume is 7.4ml / g, and the most probable pore diameter is 4nm. The molar ratio of sodium sulfonate to sulfonate in this catalyst is 1:1.

[0070] (2) Carry out cracking reaction: The acidic metal organic framework material prepared in step (1) is loaded into a reaction tube with a loading length of 1 cm. The amount of gas containing 2,2-dimethoxypropane (carrier gas is nitrogen) introduced is such that the space velocity of 2,2-dimethoxypropane is 4500 ml / h and the reaction temperature is 120°C. The reaction product is monitored by GC (gas chromatography). After the reaction is stable for 5 hours, the mass contents of 2-methoxypropylene, methanol and 2,2-dimethoxypropylene in the liquid phase obtained by the reaction are 67.7wt%, 30.1wt% and 2.1wt%, respectively, that is, the conversion rate is 97.9% and the selectivity is 99.9%. After 2000 hours of reaction, the content of 2-methoxypropylene begins to decrease, indicating that the reaction life of the above catalyst can reach 2000 hours.

[0071] Example 2

[0072] (1) Preparation of acidic metal organic framework material 2, wherein the corresponding coordination metal M is Cr, and M" is H and Na.

[0073] Add 1.04 g of RuCl3, 24.20 g of 4,4'-biphenyldicarboxylic acid, 21.40 g of sodium p-chlorobenzenesulfonate and 1000 mL of dichloromethane to the reaction bottle, carry out the substitution reaction at 50°C for 8 h, filter, wash the obtained solid three times with 100 mL of dichloromethane, wash three times with 100 mL of methanol, and dry at 100°C for 8 h to obtain 40.7 g of white powder (where M' is Na).

[0074] Afterwards, Cr(NO3)3·6H2O, the compound represented by formula (3), DMF and formic acid were subjected to coordination reaction (calcination crystallization) at a molar ratio of 2:1:2:0.5 at 120°C for 24 hours, centrifuged at 5000 rpm for 20 minutes, and then centrifuged and filtered. The solid was washed three times with 50 mL of DMF and three times with 50 mL of methanol, and then the solid was dried at 120°C for 3 hours to obtain a white solid.

[0075] 1 mol / L hydrochloric acid was added to the white solid in an amount such that the amount of hydrochloric acid used was 0.03 mol per mole of the compound represented by formula (3), and the mixture was acidified for 20 h under stirring at 25°C; the solid was filtered and rinsed three times with 50 mL of water to obtain an acidified metal organic framework material (the XRD spectrum and scanning electron microscopy confirmed that the same framework structure as that in formula (2) was obtained, wherein Cr was the coordination metal). The average particle size of the obtained metal organic framework material was 4.4 μm, and the specific surface area was 754 m 2 / g, pore volume is 8ml / g, and the most probable pore diameter is 4.5nm. The ratio of sodium sulfonate to sulfonate in this catalyst is 1.5:1.

[0076] (2) Carry out cracking reaction: The acidic metal organic framework material prepared in step (1) is loaded into a reaction tube with a loading length of 1 cm. The amount of gas containing 2,2-dimethoxypropane (carrier gas is nitrogen) introduced is such that the space velocity of 2,2-dimethoxypropane is 3600 ml / h and the reaction temperature is 120°C. The reaction product is monitored by GC. After the reaction is stable for 5 hours, the mass contents of 2-methoxypropylene, methanol and 2,2-dimethoxypropylene in the liquid phase obtained by the reaction are 61.5wt%, 29.6wt% and 7.7wt%, respectively, i.e., the reaction conversion rate is 92.3% and the selectivity is 98.7%. After 1988 hours of reaction, the content of 2-methoxypropylene begins to decrease, indicating that the reaction life of the above catalyst can reach 1988 hours.

[0077] Example 3

[0078] (1) Preparation of acidic metal organic framework material 3, wherein the corresponding coordination metal M is Zr, and M" is H and Na.

[0079] Add 0.8 g of FeCl3, 24.20 g of 4,4'-biphenyldicarboxylic acid, 21.40 g of sodium p-chlorobenzenesulfonate and 1000 mL of dichloromethane to the reaction bottle, carry out the substitution reaction at 50°C for 10 h, filter, wash the obtained solid three times with 100 mL of dichloromethane, wash three times with 100 mL of methanol, and dry at 80°C for 8 h to obtain 40.7 g of white powder (where M' is Na).

[0080] Afterwards, ZrCl4, the compound represented by formula (3), DMF and benzoic acid were subjected to coordination reaction (calcination crystallization) in a molar ratio of 2.5:1:25:5 at 110°C for 48 hours, centrifuged at 4000 rpm for 30 minutes, and then filtered. The solid was washed three times with 50 mL of DMF and three times with 50 mL of methanol, and then the solid was dried at 105°C for 8 hours to obtain a white solid.

[0081] 1 mol / L hydrochloric acid was added to the white solid in an amount such that the amount of hydrochloric acid used was 0.04 mol per mole of the compound represented by formula (3), and the mixture was acidified at 35°C for 12 hours under stirring; the solid was filtered and rinsed three times with 50 mL of water to obtain an acidified metal organic framework material (the XRD spectrum and scanning electron microscopy confirmed that the same framework structure as that in formula (2) was obtained, wherein Zr was the coordination metal). The average particle size of the obtained metal organic framework material was 6 μm, and the specific surface area was 743 m 2 / g, pore volume is 7.0ml / g, and the most probable pore diameter is 5nm. The ratio of sodium sulfonate group to sulfonate group in this catalyst is 0.67:1.

[0082] (2) Carry out cracking reaction: The acidic metal organic framework material prepared in step (1) is loaded into a reaction tube with a loading length of 2 cm. The amount of gas containing 2,2-dimethoxypropane (carrier gas is nitrogen) introduced is such that the space velocity of 2,2-dimethoxypropane is 6200 ml / h and the reaction temperature is 110°C. The reaction product is monitored by GC. After the reaction is stable for 5 hours, the mass contents of 2-methoxypropylene, methanol and 2,2-dimethoxypropylene in the liquid phase obtained by the reaction are 68.5wt%, 30.4wt% and 0.3wt%, respectively, i.e., the conversion rate is 99.7% and the selectivity is 99.2%. After 2200 hours of reaction, the content of 2-methoxypropylene begins to decrease, indicating that the reaction life of the above catalyst can reach 2200 hours.

[0083] Comparative Example 1

[0084] The method of step (2) in Example 3 was followed, except that the catalyst was an acidic resin (purchased from Inotech, model number S27899-500g). After the reaction was stable for 5 hours, the mass contents of 2-methoxypropylene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction were 45.6wt%, 31.8wt% and 7.3wt% respectively, i.e., the conversion rate was 92.7% and the selectivity was 83.4%.

[0085] Comparative Example 2

[0086] The steps (1) to (2) of Example 1 were followed, except that an excess of hydrochloric acid was added during partial acidification so that the positions corresponding to M" in the catalyst were completely H. After the reaction was stable for 1 hour, real-time monitoring by GC showed that the mass contents of 2-methoxypropylene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction were 31.2 wt%, 13.9 wt% and 24.7 wt%, respectively, indicating a conversion rate of 75.3% and a selectivity of 59.9%.

[0087] Comparative Example 3

[0088] The steps (1)-(2) of Example 1 were followed, except that partial acidification was not performed, i.e., the position corresponding to M" was completely Na. After the reaction was stable for 7 hours, the reaction was monitored in real time by GC. The mass contents of 2-methoxypropylene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction were 0, 0 and 98.6 wt %, respectively, i.e., the conversion rate was 1.4%.

[0089] It can be seen from the above examples that the method provided by the present invention is used to prepare 2-methoxypropylene, the catalytic activity is high, the reaction can be carried out at a relatively low temperature, and the yield and purity of the product are high. The fixed bed is used for the reaction, the separation of the product and the catalyst is simple, the catalyst can be repeatedly used and has a long service life, which can reduce environmental pollution and significantly reduce the synthesis cost of 2-methoxypropylene.

[0090] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing 2-methoxyolefin, characterized in that: The method comprises: in the presence of a catalyst, causing 2,2-dimethoxyalkane to undergo a cracking reaction; Wherein, the catalyst is a metal organic framework material, the ligand of the metal organic framework material is provided by a substance having a structure as shown in formula (1), and the coordination metal M is selected from one of Zn, Cr and Zr; in formula (1), M" includes H and an alkali metal element, and the alkali metal element is selected from Li, Na, K or Cs; 2. The method according to claim 1, wherein: The metal organic framework material has a structure as shown in formula (2):

3. The method according to claim 1, wherein: The metal organic framework material has an average particle size of 0.5-12 μm and a specific surface area of ​​50-1200 m 2 / g, pore volume is 1-11ml / g, and the most probable pore diameter is 0.1-9nm.

4. The method according to claim 1 or 3, wherein: The metal organic framework material has an average particle size of 1-10 μm and a specific surface area of ​​100-1100 m 2 / g, pore volume is 3-10ml / g, and the most probable pore diameter is 2-8nm; Preferably, the metal organic framework material has an average particle size of 2-7 μm and a specific surface area of ​​200-1000 m 2 / g, the pore volume is 4-9ml / g, and the most probable pore diameter is 4-6nm.

5. The method according to claim 1 or 2, wherein: In M", the molar ratio of the alkali metal element to H is (0.001-1000):1, preferably (0.005-50):1, and more preferably (0.5-5):

1.

6. The method according to claim 1, wherein: The cracking reaction method includes: passing a gas containing 2,2-dimethoxyalkane into a reactor loaded with a catalyst; Preferably, the amount of the gas containing 2,2-dimethoxyalkane introduced is such that the space velocity of 2,2-dimethoxyalkane is 3000-10000 ml / h; Preferably, the gas containing 2,2-dimethoxyalkane uses an inert gas as a carrier gas, and the inert gas is selected from at least one of nitrogen, helium and argon.

7. The method according to claim 1 or 6, wherein: The conditions of the cleavage reaction include: a temperature of 30-200°C, preferably 50-150°C; And / or, after the cracking reaction, the method further comprises: distilling the liquid phase obtained from the cracking reaction; Preferably, the distillation is carried out in a distillation tower at a distillation temperature of 30-80°C, preferably 50-60°C.

8. The method according to claim 1 or 2, wherein: The preparation method of the catalyst comprises: (1) in the presence of a first solvent and an organic acid, causing the compound represented by formula (3) to undergo a coordination reaction with a metal source to be coordinated; (2) partially acidifying the product of the coordination reaction in the presence of an inorganic acid; Wherein, in formula (3), M' is selected from Li, Na, K or Cs; the metal M in the metal source to be coordinated is selected from one of Zn, Cr and Zr; 9. The method according to claim 8, wherein: In step (1), the conditions for the coordination reaction include: temperature of 80-200° C., preferably 100-150° C.; time of 5-50 h, preferably 10-48 h; And / or, in step (1), the molar ratio of the metal source to be coordinated, the compound represented by formula (3), the first solvent and the organic acid is (1-5):1:(1-30):(0.1-10), preferably (2-3):1:(2-25):(0.5-5); And / or, the metal source to be coordinated is selected from one of Zn(NO3)2, Cr(NO3)3 and ZrCl4; and / or, the first solvent is selected from at least one of N,N-dimethylformamide, dimethyl sulfoxide and N-methylpyrrolidone, preferably N,N-dimethylformamide; And / or, in step (1), the organic acid is selected from at least one of formic acid, acetic acid and benzoic acid.

10. The method according to claim 8 or 9, wherein: In step (2), the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid, preferably hydrochloric acid; And / or, the partial acidification conditions include: temperature of 15-60°C and time of 2-36h; And / or, the amount of the inorganic acid used is 0.01-0.99 mol per mole of the compound represented by formula (3).

11. A metal organic framework material, characterized in that: The metal organic framework material is the metal organic framework material defined in any one of claims 1 to 5 or the partially acidified product described in any one of claims 8 to 10.

12. A method for preparing a metal organic framework material, characterized in that: The preparation method is a method for preparing the partially acidified product according to any one of claims 8 to 10.

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