Process for cleaving 2,2-dimethoxyalkanes and metal-organic framework materials and methods for their preparation

Abstract

The application relates to the field of metal organic framework materials, and discloses a method for cracking 2,2-dimethoxy alkane, a metal organic framework material and a preparation method thereof. The method for cracking 2,2-dimethoxy alkane comprises the following steps: contacting 2,2-dimethoxy alkane with a catalyst and performing a cracking reaction, 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 Zr, Cr and Al. The method has high catalytic activity, can perform the reaction at a lower temperature in a gas phase, has simple post-treatment, can realize the separation of products in a simple mode, has high synthesis efficiency, the catalyst structure is stable, the catalyst can be repeatedly used, and the production cost can be more favorably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of metal organic framework materials, in particular to a method for cracking 2,2-dimethoxyalkane, a metal organic framework material and a preparation method thereof. BACKGROUND

[0002] 2-methoxypropene is the simplest alkenyl ether, which is very active and very unstable. However, 2-methoxypropene is a very important synthetic raw material in many synthetic drugs, especially in the synthesis of clarithromycin, which is a key intermediate. Meanwhile, 2-methoxypropene is also an important raw material for vitamins and carotenes.

[0003] In the early stage, 2-methoxypropene 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 cumbersome post-processing and the corrosion of large amounts of sulfonic acid to industrial equipment. In 1982, Marianne et al. published a work in Tetrahedron Letters, 1982, 23(6):631-634, in which nonanoic acid was used as a catalyst, and after 4h of reaction, the yield of 2-methoxypropene could reach 71.0%. However, the use of organic acids cannot be used for fixed bed reaction, i.e. the product and the catalyst need to be classified by distillation and other methods. In 2009, Li Xiaoxi et al. published a work in Anhui Chemical Industry, 2009, 35(6):29-30, in which improvements were made on the basis of the above work, using toluene instead of diethylene glycol dimethyl ether (14.6mL) as a solvent, succinic anhydride (20g), pyridine (15.6mL), and benzoic acid (0.58g) as catalysts, the yield could reach 81%, and the product purity could reach 97%. The product was adjusted by pyridine and other acids, but it was still a homogeneous reaction, and the separation of the catalyst from the product was difficult. Some technologies use diethylene glycol dimethyl ether, which has the defects of high price, high toxicity, high boiling point, and easy miscibility with water, which need to be further improved. In 2005, Cui Wei et al. published a work, which also used gas phase cracking of 2,2-dimethoxypropane under the condition of acidic catalyst, the reaction temperature was 180-190℃, and the product was cooled at-10℃, the yield of 2-methoxypropene could reach more than 85%, but the catalyst had poor acid stability. The use of solid catalysts can better meet the needs of industrialization, but the catalysts are easy to deactivate, which leads to the increase of cost. In addition, there are problems of high reaction temperature, and the raw materials are easy to carbonize on the surface of the catalyst, which affects the efficiency and service life of the catalyst.

[0004] At present, there are still many problems in the synthesis of 2-methoxypropene. It is very important to find an effective and heterogeneous catalytic system for preparing 2-methoxypropene. At the same time, the acidity of the catalyst in the heterogeneous system needs to be controlled. The reaction is sensitive to the acidity of the catalyst, and the appropriate acidity can ensure the reaction at a lower temperature, and at the same time ensure the yield and purity of the product, and realize the simple separation of the material after the reaction, and realize the recycling of the catalyst, and control the coking in the reaction process (the existing catalysts will carbonize on the surface of the catalyst due to the high reaction temperature, which will affect the efficiency and service life of the catalyst, etc.). SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned problems existing in the prior art, provide a method for cracking 2,2-dimethoxyalkane and a metal organic framework material and a preparation method thereof, which has high catalytic activity, can react at a lower temperature in gas phase, and has simple post-treatment, can realize the separation of the product in a simple way, has high synthesis efficiency, the catalyst structure is stable, and can be repeatedly used, which is more conducive to reducing the production cost.

[0006] In order to achieve the above-mentioned purpose, one aspect of the present application provides a method for cracking 2,2-dimethoxyalkane, which comprises: contacting 2,2-dimethoxyalkane with a catalyst and performing 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 with a structure as shown in formula (1), and the coordination metal M is selected from one of Zr, Cr and Al; in formula (1), M" includes H and a metal element, and the metal element is selected from at least one of Li, Na, K, Cs, Ca and Mg;

[0007]

[0008] 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.

[0009] 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.

[0010] By using the method provided by the present application, the catalytic activity is high, the reaction can be carried out at a lower temperature in gas phase, carbonization is not easy to occur in the process, the catalyst has high efficiency and long service life; and the post-treatment is simple, the separation of the product can be realized in a simple way, the synthesis efficiency is high, the catalyst structure is stable, and the catalyst can be repeatedly used, which is more conducive to reducing environmental pollution and reducing production cost. BRIEF DESCRIPTION OF DRAWINGS

[0011] Figure 1 Figure 3 is a thermogravimetric plot of the metal organic framework material prepared in Example 1. DETAILED DESCRIPTION

[0012] The endpoints of the ranges and any values disclosed herein are not limited to the precise values recited as the exact dimensions are not, and should not be, to be construed as being critical to the scope of the invention. Any numerical range recited herein is intended to include all sub-ranges subsumed therein. For example, a range of "1 to 10" is intended to include all sub-ranges between and including the recited minimum value of 1 and the recited maximum value of 10, that is, having a minimum of 1 and a maximum of 10. Any maximum numerical limitation recited is intended to include each smaller numerical limitation subsumed therein. Numerical values are only approximations because some experiment error is unavoidable in capturing, processing and recording measurements of a chemical process. Anyway, numerical values within typically 10% of the stated values are to be considered as being within the scope of the invention.

[0013] In a first aspect, the present application provides a method for cracking 2,2-dimethoxyalkane, the method comprising: contacting 2,2-dimethoxyalkane and a catalyst and performing 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 with a structure as shown in formula (1) and the coordination metal M is selected from one of Zr, Cr and Al; in formula (1), M" includes H and a metal element, the metal element is selected from at least one of Li, Na, K, Cs, Ca and Mg;

[0014]

[0015] The inventors of the present application have found in research that, when cracking 2,2-dimethoxyalkane to prepare 2-methoxyalkene by using the above method, the catalytic activity is high, the reaction can be performed at a relatively low temperature, and the reaction can be performed in a fixed bed, the product and yield and purity are relatively high, the product and the catalyst are separated simply after the reaction, 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. By using the catalyst specially defined in the present application, the catalytic activity for cracking 2,2-dimethoxyalkane is much higher than that of the commonly used catalysts such as sulfonic acid, benzoic acid, ZSM-5 and acidic aluminum trioxide, and the synthesis efficiency of 2-methoxyalkene is greatly improved. As a very important pharmaceutical intermediate, the improvement of the synthesis efficiency of 2-methoxyalkene can greatly reduce the synthesis cost, which is extremely important for the development of the pharmaceutical industry.

[0016] 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. The 2-methoxypropene is prepared by cracking the 2,2-dimethoxypropane.

[0017] It can be understood that M" includes H and a metal element selected from at least one of Li, Na, K, Cs, Ca and Mg, which means that the catalyst contains both the structure of M" being H and the structure of M" being the above-mentioned metal element.

[0018] According to the present application, preferably, the cracking reaction is performed by feeding a gas containing 2,2-dimethoxyalkane into a reactor loaded with the catalyst.

[0019] According to a preferred embodiment of the present application, the reactor is a fixed bed reactor. The catalyst is filled in the fixed bed reactor, and the gas is fed to perform the reaction.

[0020] Preferably, the gas containing 2,2-dimethoxyalkane is fed in an amount such that the space velocity of 2,2-dimethoxyalkane is 1000-20000 ml / h.

[0021] Preferably, the gas containing 2,2-dimethoxyalkane is fed in an amount such that the space velocity of 2,2-dimethoxyalkane is 1000-20000 ml / h.

[0022] According to the present application, preferably, the cracking reaction is performed at a temperature of 25-220°C, preferably 45-155 (for example, 45, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150, 155 and any two of the above values form a range and values within the range) °C. The method provided by the present application can perform the cracking reaction at a lower temperature than the prior art, and the synthesis cost is lower.

[0023] According to the present application, preferably, after the cracking reaction, the method further comprises rectifying the liquid phase obtained by the cracking reaction. 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.

[0024] According to the present application, preferably, the rectification is performed in a rectification column at a rectification temperature of 25-85°C, preferably 45-65 (for example, 45, 50, 55, 60, 65 and any two of the above values form a range and values within the range) °C. The rectification can be performed under reduced pressure at 0.1-0.5 atm.

[0025] According to the present application, preferably, the metal-organic framework material has a structure as shown in formula (2):

[0026]

[0027] 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.

[0028] According to the present application, preferably, the average particle size of the metal organic framework material is 0.8-20 μm, the specific surface area is 300-2000 m 2 / g, the pore volume is 0.9-3 ml / g, and the most probable pore diameter is 0.1-6 nm.

[0029] Preferably, the average particle size of the metal organic framework material is 1-10 μm, the specific surface area is 500-1750 m 2 / g, the pore volume is 1-2.9 ml / g, and the most probable pore diameter is 0.2-5.5 nm.

[0030] Preferably, the average particle size of the metal organic framework material is 2-7 μm, the specific surface area is 600-1715 (for example, 600, 700, 800, 900, 1000, 1100, 1200, 1300, 1400, 1500, 1600, 1700, 1715 and any two of the above values and values within the range form a range) m 2 / g, the pore volume is 1.1-2.4 (for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 2, 2.1, 2.2, 2.3, 2.4 and any two of the above values and values within the range form a range) ml / g, and the most probable pore diameter is 0.3-5 (for example, 0.3, 1, 2, 3, 4, 5 and any two of the above values and values within the range form a range) nm.

[0031] According to the present application, preferably, in M", the molar ratio of the metal element to H is (0.001-1000):1, preferably (0.005-50):1, and more preferably (0.4-1.5):1. The catalyst is acidic, has stable sulfonic acid groups, and its framework structure is stable in water and organic solvents. The catalyst provided by the present application generally can exist more stably. And the acidity of the catalyst can be adjusted by adjusting the molar ratio of the metal element to H, to further improve the catalytic efficiency and further improve the product yield. Generally, the molar ratio of the metal element to H (i.e. the ratio of sulfonic acid metal salt root to sulfonic acid root) can be determined by thermogravimetric method. On the thermogravimetric curve, the weight of the metal organic framework material mainly appears three times of weight loss as the temperature rises. 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.

[0032] According to the present application, preferably, the preparation method of the catalyst comprises:

[0033] (1) in the presence of a first solvent and an organic acid, a compound represented by formula (3) is subjected to a coordination reaction with a metal source to be coordinated;

[0034] (2) in the presence of an inorganic acid, the product of the coordination reaction is subjected to partial acidification;

[0035] wherein, in formula (3), M' is selected from one of Li, Na, K, Cs, Ca and Mg; the metal M in the metal source to be coordinated is selected from one of Zn, Cr and Zr;

[0036]

[0037] wherein, "partial acidification" means that the metal M' is partially replaced by H, so that the finally obtained product of partial acidification has, at the position of M', part of the alkali metal element and part of H.

[0038] According to the present application, preferably, in step (1), the conditions of the coordination reaction (i.e. sintering) include a temperature of 90-220°C, preferably 100-140°C, and a time of 8-30h, preferably 20-28h.

[0039] 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 acid is (1-5):1:(3-100):(0.5-20), preferably (2-3):1:(5-80):(1-15).

[0040] According to the present application, preferably, in step (1), the metal source to be coordinated is selected from one of Al(NO3)3, Cr(NO3)3 and ZrCl4. The hydrates of the above-mentioned substances can also be used, for example Cr(NO3)3·6H2O.

[0041] According to the present application, preferably, the first solvent is selected from at least one of N,N-dimethylformamide (DMF), dioxane, dimethyl sulfoxide and N-methyl pyrrolidone.

[0042] According to the present application, preferably, in step (1), the acid is selected from at least one of formic acid, acetic acid, benzoic acid and phenylacetic acid.

[0043] After the coordination reaction, the material can be subjected to centrifugation and suction filtration, and the solid obtained after suction filtration can be sequentially subjected to washing and drying. The centrifugation can be at 3500-6000rpm for 10-40min; 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 the washing agent used in the washing is not particularly limited. The drying can be at 100-130°C for 2-10h.

[0044] 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.

[0045] According to the present application, preferably, the partially acidifying conditions include: 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 time of 1-10h (for example, the time can be 1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, 10h, and a range formed by any two of the above values and values within the range).

[0046] 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.

[0047] 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.

[0048] 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 terephthalic acid with p-chlorobenzenesulfonate in the presence of a second solvent and a metal halide.

[0049] According to the present application, preferably, the conditions of the substitution reaction include: temperature of 30-100℃, and more preferably, the temperature is 40-80℃ (for example, the temperature can be 40℃, 45℃, 48℃, 49℃, 50℃, 51℃, 52℃, 53℃, 55℃, 58℃, 60℃, 65℃, 70℃, 75℃, 80℃, and a range formed by any two of the above values and values within the range); and time of 5-30h, and more preferably, the time is 8-24h (for example, the time can be 8h, 10h, 12h, 18h, 20h, 22h, 23h, 24h, and a range formed by any two of the above values and values within the range).

[0050] According to the present application, preferably, the molar ratio of terephthalic acid, p-chlorobenzenesulfonate and the metal halide is 1:(0.7-1.5):(0.01-0.2).

[0051] According to the present application, preferably, the metal halide is at least one selected from AlCl3, RuCl3and FeCl3.

[0052] 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 30-150 ml with respect to 1 g of terephthalic acid. The metal element in the p-toluene sulfonate is taken as M'.

[0053] 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 80-120℃, and the time can be 2-8h.

[0054] 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.

[0055] 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.

[0056] The present application will be described in detail below through examples.

[0057] 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 and H in M" is measured by the ratio of the sulfonic acid metal salt root and the sulfonic acid root, that is, by the 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 450-530℃ is caused by the sulfonic acid root, and the weight loss near 530-600℃ is caused by the sulfonic acid metal salt root. Figure 1

[0058] In the following examples, the reaction tube length used in the cracking reaction (using a fixed bed reaction) is 1 meter, and the inner diameter is 1 centimeter.

[0059] In the following examples, the liquid phase obtained after the reaction is subjected to rectification (50℃, 0.2atm under reduced pressure rectification), and 2-methoxypropene, methanol and 2,2-dimethoxypropane are separated, and each substance and the corresponding content are confirmed by GC.

[0060] ​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 after reaction;

[0061] The reaction selectivity is calculated as follows: the ratio of the sum of the amount of 2-methoxypropene and the amount of methanol in the liquid phase obtained after reaction to the conversion rate of 2,2-dimethoxypropane.

[0062] Example 1

[0063] (1) Preparation of acidic metal-organic framework material 1, which corresponds to a coordination metal M of Zr and M" of H and Na.

[0064] Into a reaction bottle, 0.34 g of AlCl3, 8.3 g of terephthalic acid, 10.70 g of sodium p-chlorobenzenesulfonate and 500 mL of dichloromethane were added, and substitution reaction was carried out at 50°C for 24 h. The solid was washed with 50 mL of dichloromethane three times, 50 mL of methanol three times, and dried at 100°C for 2 h to obtain a white powder (confirmed by NMR to be a compound represented by formula (3) wherein M' is Na).

[0065] Subsequently, ZrCl4, the compound represented by formula (3) above, DMF and phenylacetic acid were subjected to coordination reaction (sintering crystal) at a molar ratio of 2.5:1:40:10 at 120°C for 24 h, centrifuged at 4000 rpm for 20 min, and then suction filtered. The solid was washed with 50 mL of DMF three times, 50 mL of methanol three times, and the solid was dried at 105°C for 3 h to obtain a white solid.

[0066] To the obtained white solid, 1 mol / L hydrochloric acid was added in an amount of 0.07 mol per mole of the compound represented by formula (3), and acidification was carried out at 25°C for 2 h with stirring. The solid was washed with 50 mL of water three times to obtain an acidified metal-organic framework material (confirmed by XRD spectrum and electron microscope scanning image to obtain the same framework structure as in formula (2) wherein Zr is a coordination metal). The average particle diameter of the obtained metal-organic framework material was 3 μm, the specific surface area was 675 m 2 / g, the pore volume was 1.5 ml / g, and the most probable pore diameter was 1.7 nm. The ratio of sodium sulfonate to sulfonate in this catalyst was 1:1.

[0067] (2) Perform a cracking reaction: load the acid metal organic framework material prepared in step (1) into a reaction tube, with a loading length of 1 cm. Pass a gas containing 2,2-dimethoxypropane (with nitrogen as the carrier gas) in an amount such that the space velocity of 2,2-dimethoxypropane is 5000 ml / h, and the reaction temperature is 100°C. Monitor the reaction product by GC (gas chromatography), and after the reaction is stable for 1 hour, monitor 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction online. When the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane is 68.1 wt%, 30.2 wt% and 1.5 wt% respectively, the conversion rate is 98.5% and the selectivity is 99.7%. After 1000 hours of reaction, the content of 2-methoxypropene begins to decrease, indicating that the reaction life of the above-mentioned catalyst is 1000 hours.

[0068] Example 2

[0069] (1) Preparation of acid metal organic framework material 2, which corresponds to a coordination metal M of Zr, and M" of H and Na.

[0070] Into a reaction bottle, 0.34 g of AlCl3, 8.3 g of terephthalic acid, 10.70 g of sodium p-chlorobenzenesulfonate and 500 mL of dichloromethane are placed, and a substitution reaction is performed at 50°C for 24 h. The solid is washed with 50 mL of dichloromethane three times, washed with 50 mL of methanol three times, and dried at 100°C for 2 h to obtain a white powder (confirmed by nuclear magnetic resonance to be a compound represented by formula (3), wherein M' is Na).

[0071] Subsequently, ZrCl4, the compound represented by formula (3) described above, DMF and phenylacetic acid are placed in a ratio of 2.5:1:40:10 by mole, and a coordination reaction (sintering crystal) is performed at 120°C for 24 h. After centrifugation at 4000 rpm for 30 min, the solid is filtered, washed with 50 mL of DMF three times, washed with 50 mL of methanol three times, and dried at 105°C for 3 h to obtain a white solid.

[0072] The obtained white solid is added with 2 mol / L hydrochloric acid in an amount of 0.06 mol per mole of the compound represented by formula (3), and acidification is performed at 25°C for 2 h under stirring. The solid is washed with 50 mL of water three times to obtain an acidified metal organic framework material (confirmed by XRD spectrum and electron microscopy scanning to obtain the same framework structure as in formula (2), wherein Zr is a coordination metal), wherein the average particle size of the obtained metal organic framework material is 7 μm, the specific surface area is 685 m 2 / g, the pore volume is 1.7 ml / g, and the most probable pore diameter is 1.8 nm. The ratio of sodium sulfonate to sulfonic acid in the catalyst is 0.8:1.

[0073] (2) Perform a cleavage reaction: load the acid metal organic framework material prepared in step (1) into a reaction tube, with a loading length of 1 cm. Pass a gas containing 2,2-dimethoxypropane (the carrier gas is nitrogen) in an amount such that the space velocity of 2,2-dimethoxypropane is 6000 ml / h, and the reaction temperature is 120°C. Monitor the reaction product by GC, and after the reaction is stable for 1 hour, measure the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction, which is 68.0 wt%, 30.2 wt% and 0.8 wt% respectively, i.e. the conversion rate is 99.2% and the selectivity is 99%. After 1000 hours of reaction, the content of 2-methoxypropene begins to decrease, indicating that the reaction life of the above-mentioned catalyst is 1000 hours.

[0074] Example 3

[0075] (1) Preparation of acid metal organic framework material 3, which corresponds to a coordination metal M of Cr, M" of H and Na.

[0076] Add 0.52 g of RuCl3, 8.3 g of terephthalic acid, 10.7 g of sodium p-chlorobenzenesulfonate and 1000 mL of dichloromethane to a reaction bottle, and perform a substitution reaction at 50°C for 24 h. Filter, wash the solid with 100 mL of dichloromethane three times, wash with 100 mL of methanol three times, and dry at 80°C for 8 h to obtain a white powder (confirmed by NMR to be a compound represented by formula (3), wherein M' is Na).

[0077] Subsequently, perform a coordination reaction (sintering crystal) of Cr(NO3)3 6H2O, the compound represented by formula (3) described above, DMF and acetic acid at a molar ratio of 2:1:5:1.5 at 120°C for 24 h, centrifuge at 5000 rpm for 15 min, then filter, wash the solid with 50 mL of DMF three times, wash with 50 mL of methanol three times, and dry the solid at 105°C for 5 h to obtain a white solid.

[0078] Add 2 mol / L hydrochloric acid to the obtained white solid in an amount such that the amount of the hydrochloric acid is 0.05 mol per mol of the compound represented by formula (3), and perform acidification at 25°C for 3 h with stirring; filter, and wash the solid with 50 mL of water three times to obtain an acidified metal organic framework material (confirmed by XRD spectrum and scanning electron microscope to obtain the same framework structure as in formula (2), wherein Cr is a coordination metal). The average particle size of the obtained metal organic framework material is 6 μm, the specific surface area is 726 m 2 / g, the pore volume is 1.3 ml / g, and the most probable pore diameter is 1.1 nm. The ratio of sodium sulfonate to sulfonic acid in the catalyst is 0.8:1.

[0079] (2) Perform a cleavage reaction: load the acid metal organic framework material prepared in step (1) into a reaction tube, with a loading length of 1 cm. Pass a gas containing 2,2-dimethoxypropane (the carrier gas is nitrogen) in an amount such that the space velocity of 2,2-dimethoxypropane is 6000 ml / h, and the reaction temperature is 100°C. Monitor the reaction product by GC, and after the reaction is stable for 1 hour, measure the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction to be 66.9 wt%, 29.7 wt% and 2.6 wt%, respectively, i.e. the conversion rate is 97.4% and the selectivity is 99.2%. After 1000 hours of reaction, the content of 2-methoxypropene begins to decrease, indicating that the reaction life of the above-mentioned catalyst can reach 1000 hours.

[0080] Example 4

[0081] (1) Preparation of acid metal organic framework material 3, which corresponds to a coordination metal M of Al, and M" of H and Li.

[0082] Add 1.04 g of RuCl3, 16.6 g of terephthalic acid, 19.64 g of lithium p-chlorobenzenesulfonate and 1000 mL of dichloromethane to a reaction bottle, and perform a substitution reaction at 50°C for 24 h. Filter, wash the solid with 100 mL of dichloromethane three times, wash with 100 mL of methanol three times, and dry at 80°C for 8 h to obtain a white powder (confirmed by NMR to be a compound represented by formula (3), wherein M' is Li).

[0083] Then, perform a coordination reaction (sintering crystal) of Al(NO3)3, the compound represented by formula (3), dioxane and acetic acid at a molar ratio of 3:1:80:12 at 120°C for 24 h, centrifuge at 6000 rpm for 12 min, then filter, wash the solid with 50 mL of DMF three times, wash with 50 mL of methanol three times, and dry the solid at 105°C for 3 h to obtain a white solid.

[0084] Add 5 mol / L hydrochloric acid to the white solid obtained in step (1) in an amount such that the amount of hydrochloric acid is 0.03 mol per mol of the compound represented by formula (3), and perform acidification at 50°C for 1 h with stirring; filter, and wash the solid with 50 mL of water three times to obtain an acid metal organic framework material (confirmed by XRD spectrum and scanning electron microscope to obtain the same framework structure as in formula (2), wherein Al is a coordination metal). The average particle size of the obtained metal organic framework material is 5 μm, the specific surface area is 1203 m 2 / g, the pore volume is 2.4 ml / g, and the most probable pore diameter is 3.0 nm. The ratio of lithium sulfonate to sulfonic acid in the catalyst is 0.43:1.

[0085] (2) Perform the cracking reaction: The acid metal organic framework material prepared in step (1) is loaded into a reaction tube, with a loading length of 2 cm. The amount of 2,2-dimethoxypropane-containing gas (nitrogen as the carrier gas) is such that the space velocity of 2,2-dimethoxypropane is 6000 ml / h, and the reaction temperature is 110°C. The reaction product is monitored by GC, and after 1 hour of stable reaction, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 68.3 wt%, 30.4 wt%, 0.7 wt%, i.e. the conversion rate is 99.3%, and the selectivity is 99.4%. After 900 hours of reaction, the content of 2-methoxypropene begins to decrease, indicating that the reaction life of the above-mentioned catalyst can reach 900 hours.

[0086] Comparative Example 1

[0087] According to the method of step (2) in Example 4, except that the catalyst is an acid ceramic filler (purchased from Inoceram, model number I11206). After 1 hour of stable reaction, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 35.9 wt%, 15.9 wt%, 37.2 wt%, i.e. the conversion rate is 62.8%, and the selectivity is 82.3%. The selectivity is low, and there is no other byproduct in the product, indicating that organic matter in the system has undergone coking and carbonization on the surface of the catalyst.

[0088] Comparative Example 2

[0089] 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 1 hour of stable reaction, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 45.9 wt%, 30.6 wt%, 10.7 wt%, i.e. the conversion rate is 89.3%, and the selectivity is 85.6%.

[0090] Comparative Example 3

[0091] According to steps (1)-(2) of Example 1, except that partial acidification is not performed, i.e. the corresponding position of M" in the catalyst is completely Na. After 1 hour of stable reaction, the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction is 0, 0, 99.9 wt%, and the conversion rate is 0.

[0092] Comparative Example 4

[0093] The cleavage reaction was carried out according to step (2) in Example 1 using UiO-66 MOF material (i.e. metal organic framework material without sulfonic acid groups) as catalyst. The reaction was monitored by GC at 1 hour after the reaction was stable, and the mass content of 2-methoxypropene, methanol and 2,2-dimethoxypropane in the liquid phase obtained by the reaction was 0, 0, 99.9wt%, i.e. the conversion rate was 0.

[0094] As can be seen from the above examples and comparative examples, the method provided by the present application has high catalytic activity for cleaving 2,2-dimethoxypropane, can be carried out at a lower temperature in gas phase, has simple post-treatment, can realize separation of the product in a simple way, has high synthesis efficiency, the catalyst structure is stable and can be repeatedly used, and is more conducive to reducing production cost.

[0095] The preferred embodiments of the present application are 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 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 belong to the protection scope of the present application.

Claims

1. A process for cleaving 2,2-dimethoxyalkanes, characterized in that, The method comprises: contacting 2,2-dimethoxy alkane and a catalyst and performing 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 with a structure as shown in formula (1), and the coordination metal M is selected from one of Zr, Cr and Al; in formula (1), M" is H and a metal element selected from at least one of Li, Na and K; （1）； The metal organic framework material has a structure as shown in formula (2): （2）。 2. The method of claim 1, wherein, The cracking reaction is performed by feeding a gas containing 2,2-dimethoxy alkane into a reactor loaded with the catalyst.

3. The method of claim 2, wherein, The feeding amount of the gas containing 2,2-dimethoxy alkane is such that the space velocity of 2,2-dimethoxy alkane is 1000-20000 ml / h.

4. The method of claim 1 or 2, wherein, The cracking reaction is performed at a temperature of 25-220 ℃; And / or, after the cracking reaction, the method further comprises: performing rectification on the liquid phase obtained by the cracking reaction.

5. The method of claim 4, wherein, The cracking reaction is performed at a temperature of 45-155 ℃; And / or, the rectification is performed in a rectification tower at a rectification temperature of 25-85 ℃.

6. The method of claim 5, wherein, The rectification temperature is 45-65 ℃.

7. The method of claim 1, wherein, The metal organic framework material has an average particle size of 0.8-20 μm, a specific surface area of 300-2000 m 2 / g, a pore volume of 0.9-3 ml / g, and a most probable pore diameter of 0.1-6 nm.

8. The method of claim 7, wherein, The metal organic framework material has an average particle size of 1-10 μm, a specific surface area of 500-1750 m 2 / g, a pore volume of 1-2.9 ml / g, and a most probable pore diameter of 0.2-5.5 nm.

9. The method of claim 8, wherein, The metal organic framework material has an average particle size of 2-7 μm, a specific surface area of 600-1715 m 2 / g, a pore volume of 1.1-2.4 ml / g, and a most probable pore diameter of 0.3-5 nm.

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

1.

11. The method of claim 10, wherein, In M", the molar ratio of the metal element to H is (0.005-50):

1.

12. The method of claim 11, wherein, In M", the molar ratio of the metal element to H is (0.4-1.5):

1.

13. 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 one of Li, Na and K; the metal M in the metal source to be coordinated is selected from one of Zn, Cr and Zr; （3）。 14. The method of claim 13, wherein, In step (1), the coordination reaction is performed at a temperature of 90-220 ℃ for 8-30 h; 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 acid is (1-5):1:(3-100):(0.5-20).

15. The method of claim 13, wherein, In step (1), the coordination reaction is performed at a temperature of 100-140 ℃ for 20-28 h; 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 acid is (2-3):1:(5-80):(1-15).

16. The method of claim 13 or 14, wherein, In step (1), the metal source to be coordinated is selected from one of Al(NO3)3, Cr(NO3)3 and ZrCl4; And / or, the first solvent is selected from at least one of N,N-dimethylformamide, dioxane, dimethyl sulfoxide and N-methyl pyrrolidone; And / or, in step (1), the acid is selected from at least one of formic acid, acetic acid, benzoic acid and phenylacetic acid.

17. The method of claim 13, wherein, In step (2), the inorganic acid is selected from at least one of hydrochloric acid, sulfuric acid and nitric acid; And / or, the partial acidification is performed at a temperature of 15-60 ℃ for 1-10 h; And / or, the amount of the inorganic acid is 0.01-0.99 mol per mole of the compound shown in formula (3).

18. The method of claim 13, wherein, In step (2), the inorganic acid is hydrochloric acid.

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