Methods of making 2-methoxy alkenes and metal-organic frameworks and methods of making the same

Abstract

The application relates to the field of metal organic framework materials, and discloses a method for preparing 2-methoxy alkene, a metal organic framework material and a preparation method thereof. The method comprises the following steps: carrying out a 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 method provided by the application has high catalytic activity in the preparation of 2-methoxy propylene, the catalyst can be repeatedly used, 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.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal organic framework materials, in particular, to a method for preparing 2-methoxy olefin and a metal organic framework material and a method for preparing the same. BACKGROUND

[0002] 2-methoxy propylene is very active and unstable, and is difficult to be prepared in industry. However, 2-methoxy propylene is a very important synthetic material in many synthetic drugs, especially in the synthesis of clarithromycin, which is a key intermediate. Meanwhile, 2-methoxy propylene is also an important raw material for vitamins and carotenes.

[0003] In the early stage, 2-methoxy propylene was prepared by cracking 2,2-dimethoxypropane in liquid phase, mostly using alkanes as solvents and sulfonic acid as catalyst. However, this method was gradually eliminated due to the relatively complicated post-treatment and the corrosion of large amounts of sulfonic acid to industrial equipment. In 2002, Yang Shumin et al. published in Fine Chemical Intermediates, 2002, 321: (20-21) that 2,2-dimethoxypropane was catalytically cracked at about 115℃ using diethylene glycol dimethyl ether as solvent, succinic anhydride, pyridine and benzoic acid as catalysts, with a yield of 80.6% and a product purity of 98%. This process reduced the use of diethylene glycol dimethyl ether and protected the environment. However, diethylene glycol dimethyl ether is expensive, toxic, has a high boiling point and is easily miscible with water, which needs to be further improved. In 2009, Li Xiaoxi et al. published in Anhui Chemical Industry, 2009, 35(6): 29-30 that toluene was used to replace diethylene glycol dimethyl ether (14.6 mL) as solvent, and succinic anhydride (20 g), pyridine (15.6 mL) and benzoic acid (0.58 g) were used as catalysts, with a yield of 81%. However, this is still a homogeneous reaction, and the separation of catalyst from product is difficult. In 1998, Dietrich et al. published in patent application 5767325.1998-6-16 that ZSM-5 type catalyst was used to catalytically crack 2,2-dimethoxypropane in gas phase, with a reaction temperature of 280-340℃, a product yield of 83.3% and almost no decrease in catalyst activity before and after reaction. 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 complex.

[0004] At present, in the production of 2-methoxy propylene, there are still many problems, such as great influence of solvent in homogeneous catalysis, complicated post-treatment, difficult separation of product, low yield and purity, discontinuous production, high reaction temperature and high synthesis cost. SUMMARY

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

[0006] To achieve the above-mentioned purpose, the present application provides a method for preparing 2-methoxy olefin, which comprises: causing 2,2-dimethoxy alkane to undergo a cracking reaction in the presence of a catalyst;

[0007] The catalyst is a metal organic framework material, the ligand of the metal organic framework material is provided by a substance with 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 selected from Li, Na, K or Cs.

[0008]

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

[0011] When the method provided by the present application is used to prepare 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. In addition, a fixed bed reaction can be used, the product is easy to separate from the catalyst, the catalyst can be repeatedly used and has a long service life, the environmental pollution can be reduced, and the synthesis cost of 2-methoxy olefin can be significantly reduced. BRIEF DESCRIPTION OF DRAWINGS

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

[0013] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be roughly about the ranges or values. The endpoints of the ranges of values, the endpoints of the ranges of values, and the individual values can be combined with one another to create new ranges or values, which are to be considered disclosed herein, unless otherwise indicated or unless it is clear from the context that the combination is not intended.

[0014] In a first aspect, the present application provides a method for preparing 2-methoxyalkene, which comprises: cracking 2,2-dimethoxyalkane 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 with 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 selected from Li, Na, K or Cs;

[0016]

[0017] The inventors of the present application found in research that when the above method is used to prepare 2-methoxyalkene, 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 yield and purity are relatively high, the separation of the product from the catalyst after the reaction is simple, the catalyst can be repeatedly used and has a long service life, the environmental pollution can be reduced, and the synthesis cost of 2-methoxyalkene can be significantly reduced. When the catalyst specified in the present application is used to catalyze the synthesis of 2-methoxyalkene, the catalytic activity is much higher than that of the commonly used catalysts such as sulfonic acid, benzoic acid, ZSM-5 and acidic aluminum oxide, which greatly improves the synthesis efficiency of 2-methoxyalkene. As a very important pharmaceutical intermediate, the improvement of the synthesis efficiency of 2-methoxyalkene can greatly reduce its synthesis cost, which is extremely important for the development of the pharmaceutical industry.

[0018] wherein it can be understood that in order to obtain 2-methoxyalkene by cracking, the number of carbon atoms 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 application, the 2,2-dimethoxyalkane is 2,2-dimethoxypropane, and the 2-methoxyalkene is 2-methoxypropene.

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

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

[0021]

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

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

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

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

[0026] According to the present application, 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 benzene sulfonic acid biphenyl structure, is stable in structure, acidic, and 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 (i.e. the ratio of sulfonic acid metal salt root to sulfonic acid root) can be determined by thermogravimetric method. In the thermogravimetric curve, the weight of the metal organic framework material mainly appears three times of weight loss as the temperature rises. According to the functional groups and organic common sense, the first time is caused by the weight loss of sulfonic acid root, the second time is caused by the sulfonic acid metal salt root, and the last time is the complete combustion of the organic framework.

[0027] The catalyst provided by the present application can generally exist more stably. Among them, the catalyst has a relatively stable sulfonic acid group, and the framework structure can exist stably in water and organic solvents.

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

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

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

[0031] According to the present application, preferably, the gas containing 2,2-dimethoxyalkane is carried by a non-reactive gas selected from at least one of nitrogen, helium and argon.

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

[0033] According to the present application, preferably, after the cleavage reaction, the method further comprises: subjecting the liquid phase obtained from the cleavage reaction to rectification. The liquid phase obtained after the reaction generally contains 2-methoxyalkene, methanol and 2,2-dimethoxyalkane, and the 2-methoxyalkene can be sufficiently purified by rectification. By using the method of the present application, the 2-methoxyalkene can be separated and purified in a simple manner.

[0034] According to the present application, preferably, the rectification is performed in a rectification column, and the rectification temperature is 30-80°C, more preferably 50-60 (for example, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 and any range formed by any two of the above values and values within the range) °C. For example, the rectification can be performed under reduced pressure of 0.1-0.5 atm.

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

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

[0037] (2) subjecting the product of the coordination reaction to partial acidification in the presence of an inorganic acid;

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

[0039]

[0040] wherein "partially acidifying" means that the alkali metal M' is partially replaced by H so that the finally obtained partially acidified product, wherein the position of M' is partially still an alkali metal element and partially H.

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

[0042] According to the present application, 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 application, preferably, the metal source to be coordinated is selected from one of Zn(NO3)2, Cr(NO3)3 and ZrCl4. The above-mentioned 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. can be used.

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

[0045] According to the present application, 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 suction filtered, and the solid obtained after suction filtration can be sequentially washed and dried. The centrifugation condition can be 3500-6000 rpm, and the time can be 20-30 min; in the washing, DMF can be used for washing 2-4 times first, and then methanol can be used for washing 2-4 times, and the amount of the washing agent used in the washing is not particularly limited. The drying temperature can be 100-130℃, and the time can be 2-10h.

[0047] According to the present application, preferably, in step (2), the inorganic acid is at least one selected from hydrochloric acid, sulfuric acid and nitric acid, and more preferably, the inorganic acid is 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 can be 0.8-8 mol / L.

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

[0049] According to the present application, preferably, the amount of the inorganic acid used is 0.01-0.99 mol per mol of the compound represented by formula (3). In this way, partial acidification can be ensured.

[0050] After the partial acidification is completed, the material obtained by the partial acidification can be suction filtered, and the obtained solid can be washed with water for 2-4 times. The amount of water used for washing is not particularly limited.

[0051] In the present application, the method for obtaining the compound represented by formula (3) is not particularly limited. Preferably, the preparation step of the compound represented by formula (3) includes: performing a substitution reaction on 4,4'-diphenyldicarboxylic acid and p-chlorobenzenesulfonate in the presence of a second solvent and a metal halide.

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

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

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

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

[0056] After the substitution reaction is completed, the material after the substitution reaction can be sequentially subjected to suction filtration, washing and drying. Washing can be performed using the same washing agent as the second solvent, and the number of times can be 2-4 times, and then methanol can be used for washing, and the number of times can be 2-4 times; the drying temperature can be 80-100°C, and the time can be 5-8h.

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

[0058] In a third aspect, the present application provides a preparation method of a metal organic framework material, which is the preparation method of the partially acidified product of the first aspect.

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

[0060] In the following examples, the average particle size is measured by Thermo Scientific TM Apreo scanning electron microscope, the specific surface area, pore volume, and most probable pore diameter are measured by a physical adsorption instrument Anton Paar QuantaTec. In the catalyst, the molar ratio of the alkali metal element to H in M" is determined by the ratio of the sulfonic acid metal salt root to the sulfonic acid root, that is, by thermogravimetric method: the weight of the material mainly appears three times of weight loss as the temperature rises, the first time is caused by the weight loss of the sulfonic acid root, and the second time is caused by the sulfonic acid metal salt root. For example, as shown in the metal organic framework material prepared in Example 1, the weight loss near 300-500°C is caused by the sulfonic acid root, and the weight loss near 500-600°C is caused by the sulfonic acid metal salt root. Figure 1

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

[0062] In the following examples, the liquid phase obtained after the reaction is subjected to rectification (50°C, 0.2atm under reduced pressure rectification), and 2-methoxy propylene, methanol and 2,2-dimethoxypropane are separated, and each substance and the corresponding content are confirmed by GC.

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

[0064] The reaction selectivity calculation method is: the ratio of the sum of the amount of 2-methoxy propylene and the amount of methanol in the liquid phase obtained by reaction to the conversion rate value of 2,2-dimethoxypropane.

[0065] Example 1 ​

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

[0067] 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 were added to a reaction flask. The substitution reaction was carried out at 50 °C for 12 h. The mixture was filtered, and the resulting solid was washed three times with 100 mL of chlorobenzene and three times with 100 mL of methanol. The solid was dried at 80 °C for 5 h to obtain 40.7 g of white powder (where M' is Na).

[0068] Subsequently, Zn(NO3)2·8H2O, the compound shown in formula (3), DMF and acetic acid were subjected to a coordination reaction (calcination crystallization) at 100℃ in a molar ratio of 2.5:1:25:5 for 24 h. After centrifugation at 4000 rpm for 20 min, the mixture was filtered. The solid was washed three times with 50 mL of DMF and three times with 50 mL of methanol. The solid was then dried at 105℃ for 5 h to obtain a white solid.

[0069] 6 mol / L hydrochloric acid was added to a white solid, with an amount such that the amount of hydrochloric acid was 0.07 mol per mole of the compound represented by formula (3). The mixture was acidified at 35°C for 5 h with stirring. The solid was then filtered and washed three times with 50 mL of water to obtain an acidified metal-organic framework material (the same framework structure as in formula (2) was confirmed by XRD and scanning electron microscopy, where Zn is the coordinating metal). The obtained metal-organic framework material had an average particle size of 5 μm and a specific surface area of ​​965 m². 2 The catalyst has a pore volume of 7.4 ml / g and a most probable pore size of 4 nm. The molar ratio of sodium sulfonate to sulfonate in this catalyst is 1:1.

[0070] (2) Cracking reaction: The acidic metal-organic framework material obtained in step (1) was loaded into a reaction tube with a loading length of 1 cm. The flow rate of 2,2-dimethoxypropane gas (carrier gas was nitrogen) was such that the space velocity of 2,2-dimethoxypropane was 4500 ml / h, and the reaction temperature was 120 °C. The reaction products were monitored by GC (gas chromatography). After the reaction stabilized for 5 hours, the mass contents of 2-methoxypropene, methanol, and 2,2-dimethoxypropane in the liquid phase were 67.7 wt%, 30.1 wt%, and 2.1 wt%, respectively, which means the conversion rate was 97.9% and the selectivity was 99.9%. After 2000 hours of reaction, the content of 2-methoxypropene began to decrease, indicating that the reaction lifetime of the above catalyst could reach 2000 hours.

[0071] Example 2

[0072] (1) Preparation of acidic metal organic framework material 2, which corresponds to a coordination metal M of Cr, M" of H and Na.

[0073] Into a reaction bottle, 1.04 g of RuCl3, 24.20 g of 4,4'-diphenyldicarboxylic acid, 21.40 g of sodium p-chlorobenzenesulfonate and 1000 mL of dichloromethane were added, and substitution reaction was carried out at 50°C for 8 h. The obtained solid was washed with 100 mL of dichloromethane for 3 times, 100 mL of methanol for 3 times, and dried at 100°C for 8 h to obtain a white powder (M' is Na) 40.7 g.

[0074] Then, Cr(NO3)3-6H2O, the compound represented by formula (3), DMF and formic acid were subjected to coordination reaction (sintering crystal) at 120°C for 24 h at a molar ratio of 2:1:2:0.5, centrifuged at 5000 rpm for 20 min, and then centrifugal filtration was carried out. The solid was washed with 50 mL of DMF for 3 times, 50 mL of methanol for 3 times, and then the solid was dried at 120°C for 3 h to obtain a white solid.

[0075] Into the white solid, 1 mol / L of hydrochloric acid was added in an amount of 0.03 mol per mole of the compound represented by formula (3), and acidification was carried out at 25°C for 20 h under stirring. Filtration was carried out, and the solid was washed with 50 mL of water for 3 times to obtain an acidified metal organic framework material (the same framework structure as formula (2) was confirmed by XRD spectrum and scanning electron microscope, in which Cr is a coordination metal). The average particle size of the obtained metal organic framework material was 4.4 μm, the specific surface area was 754 m2 / g, the pore volume was 8 ml / g, and the most probable pore diameter was 4.5 nm. The ratio of sodium sulfonate to sulfonic acid in the catalyst was 1.5:1. 2

[0076] (2) Cleavage reaction was carried out: the acidic metal organic framework material prepared in step (1) was loaded into a reaction tube, and the loading length was 1 cm. The amount of gas containing 2,2-dimethoxypropane (the carrier gas was nitrogen) was such that the space velocity of 2,2-dimethoxypropane was 3600 ml / h, and the reaction temperature was 120°C. The reaction product was monitored by GC, and after 5 hours of stable reaction, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase of the reaction product was 61.5 wt%, 29.6 wt% and 7.7 wt% respectively, that is, the conversion rate was 92.3%, and the selectivity was 98.7%. After 1988 hours of reaction, the content of 2-methoxypropene began to decrease, indicating that the reaction life of the above-mentioned catalyst was 1988 hours.

[0077] Example 3

[0078] ​(1) Preparation of acidic metal organic framework material 3, which corresponds to a coordination metal M of Zr, M" of H and Na.

[0079] Into a reaction bottle, 0.8 of FeCl3, 24.20 g of 4,4'-diphenyldicarboxylic acid, 21.40 g of sodium p-chlorobenzenesulfonate and 1000 mL of dichloromethane were added, and substitution reaction was carried out at 50°C for 10 h. The obtained solid was washed with 100 mL of dichloromethane three times, 100 mL of methanol three times, and dried at 80°C for 8 h to obtain a white powder (wherein M' is Na) 40.7 g.

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

[0081] To the white solid, 1 mol / L of hydrochloric acid was added in an amount of 0.04 mol per mol of the compound represented by formula (3), and acidification was carried out at 35°C for 12 h with stirring. The solid was washed with 50 mL of water three times to obtain an acidified metal organic framework material (the same framework structure as in formula (2) was confirmed by XRD pattern and scanning electron microscope, wherein Zr is a coordination metal). The average particle diameter of the obtained metal organic framework material was 6 μm, the specific surface area was 743 m2 / g, the pore volume was 7.0 ml / g, and the most probable pore diameter was 5 nm. The ratio of sodium sulfonate to sulfonic acid in the catalyst was 0.67:1. 2

[0082] (2) Cleavage reaction was carried out: the acidic metal organic framework material prepared in step (1) was loaded into a reaction tube, and the loading length was 2 cm. The amount of gas containing 2,2-dimethoxypropane (carrier gas: nitrogen) was such that the space velocity of 2,2-dimethoxypropane was 6200 ml / h, and the reaction temperature was 110°C. The reaction product was monitored by GC, and after 5 hours of stable reaction, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the reaction liquid phase was 68.5 wt%, 30.4 wt%, 0.3 wt%, i.e. the conversion rate was 99.7% and the selectivity was 99.2%. After 2200 hours of reaction, the content of 2-methoxypropene began to decrease, indicating that the reaction life of the above catalyst was 2200 hours.

[0083] Comparative Example 1

[0084] ​According to the method of step (2) in Example 3, except that the catalyst is an acidic resin (purchased from Inoke, model S27899-500g). After the reaction is stable for 5 hours, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 45.6wt%, 31.8wt%, 7.3wt% by real-time monitoring by GC, i.e. the conversion rate is 92.7% and the selectivity is 83.4%.

[0085] Comparative Example 2

[0086] According to steps (1)-(2) of Example 1, except that an excess of hydrochloric acid is added during partial acidification so that the corresponding position of M" in the catalyst is completely H. After the reaction is stable for 1 hour, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 31.2wt%, 13.9wt%, 24.7wt% by real-time monitoring by GC, i.e. the conversion rate is 75.3% and the selectivity is 59.9%.

[0087] Comparative Example 3

[0088] According to steps (1)-(2) of Example 1, except that no partial acidification is performed, i.e. the corresponding position of M" is completely Na. After the reaction is stable for 7 hours, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 0, 0, 98.6wt% by real-time monitoring by GC, i.e. the conversion rate is 1.4%.

[0089] As can be seen from the above examples, the method provided by the present application has high catalytic activity, the reaction can be performed at a relatively low temperature, the yield and purity of the product are high, the product and the catalyst can be separated simply using a fixed bed, the catalyst can be repeatedly used and has a long service life, environmental pollution can be reduced, and the synthesis cost of 2-methoxypropene can be significantly reduced.

[0090] The preferred embodiments of the present application have been described in detail above, but the present application is not limited thereto. Within the technical concept of the present application, various simple modifications can be made to the technical solutions of the present application, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be considered as disclosed by the present application and fall within the protection scope of the present application.

Claims

1. A process for the preparation of 2-methoxy alkenes, characterized in that, The method comprises: performing a cracking reaction on 2,2-dimethoxyalkane in the presence of a catalyst; The catalyst is a metal organic framework material, the ligand of the metal organic framework material is provided by a substance with 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" is H and an alkali metal element selected from Li, Na or K; （1）； The metal organic framework material has a structure as shown in formula (2): （2）。 2. The method of claim 1, wherein, The metal organic framework material has an average particle size of 0.5-12 μm, a specific surface area of 50-1200 m 2 / g, a pore volume of 1-11 ml / g, and a most probable pore diameter of 0.1-9 nm.

3. The method of claim 1 or 2, wherein, The metal organic framework material has an average particle size of 1-10 μm, a specific surface area of 100-1100 m 2 / g, a pore volume of 3-10 ml / g, and a most probable pore diameter of 2-8 nm.

4. The method of claim 3, wherein, The metal organic framework material has an average particle size of 2-7 μm, a specific surface area of 200-1000 m 2 / g, a pore volume of 4-9 ml / g, and a most probable pore diameter of 4-6 nm.

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

1.

6. The method of claim 5, wherein, In M", the molar ratio of the alkali metal element to H is (0.005-50):

1.

7. The method of claim 6, wherein, In M", the molar ratio of the alkali metal element to H is (0.5-5):

1.

8. The method of claim 1, wherein, The cracking reaction is performed by feeding a gas containing 2,2-dimethoxyalkane into a reactor loaded with the catalyst.

9. The method of claim 8, wherein, The feeding amount of the gas containing 2,2-dimethoxyalkane is such that the space velocity of 2,2-dimethoxyalkane is 3000-10000 ml / h.

10. The method of claim 8 or 9, wherein, The gas containing 2,2-dimethoxyalkane is carried by a non-reactive gas selected from at least one of nitrogen, helium and argon.

11. The method of claim 1 or 8, wherein, The cracking reaction is performed at a temperature of 30-200℃. And / or, after the cracking reaction, the method further comprises: performing rectification on the liquid phase obtained by the cracking reaction.

12. The method of claim 11, wherein, The cracking reaction is performed at a temperature of 50-150℃.

13. The method of claim 11, wherein, The rectification is performed in a rectification tower at a rectification temperature of 30-80℃.

14. The method of claim 13, wherein, The rectification temperature is 50-60℃.

15. The method of claim 1, wherein, The preparation method of the catalyst comprises: (1) performing a coordination reaction on a compound shown in formula (3) and a metal source to be coordinated in the presence of a first solvent and an organic acid; (2) performing partial acidification on the product of the coordination reaction in the presence of an inorganic acid; In formula (3), M' is selected from Li, Na or K; and the metal M in the metal source to be coordinated is selected from one of Zn, Cr and Zr; （3）。 16. The method of claim 15, wherein, In step (1), the coordination reaction is performed at a temperature of 80-200℃ for 5-50h. And / or, in step (1), the molar ratio of the metal source to be coordinated, the compound shown in formula (3), the first solvent and the organic acid is (1-5):1:(1-30):(0.1-10). 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-methyl pyrrolidone. And / or, in step (1), the organic acid is selected from at least one of formic acid, acetic acid and benzoic acid.

17. The method of claim 16, wherein, In step (1), the coordination reaction is performed at a temperature of 100-150℃ for 10-48h. And / or, in step (1), the molar ratio of the metal source to be coordinated, the compound shown in formula (3), the first solvent and the organic acid is (2-3):1:(2-25):(0.5-5). And / or, the first solvent is N,N-dimethylformamide.

18. The method of any one of claims 15-17, wherein, In step (2), the inorganic acid is at least one selected from the group consisting of hydrochloric acid, sulfuric acid and nitric acid; And / or, the partially acidified conditions include: temperature is 15-60℃, time is 2-36h; And / or, the inorganic acid is used in an amount of 0.01-0.99 mol per mole of the compound shown in formula (3).

19. The method of claim 18, wherein, In step (2), the inorganic acid is hydrochloric acid.

20. A metal organic framework material, characterized in that, The metal-organic framework material is a metal-organic framework material as defined in any one of claims 1-14 or a partially acidified product as described in any one of claims 15-19.

21. A method of preparing a metal organic framework material, characterized in that, The preparation method is a preparation method of a partially acidified product as described in any one of claims 15-19.

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