阅读说明：本技术 1,1-二烷氧基烷烃的制备方法 (Process for preparing 1, 1-dialkoxyalkanes ) 是由 谢明观 王永睿 慕旭宏 于 2019-10-22 设计创作，主要内容包括：本发明涉及催化化学领域,公开了一种1,1-二烷氧基烷烃的制备方法,其中,所述制备方法包括：在催化剂的存在下,将R-1OH所示醇与R-2-CHO所示醛接触反应,所述催化剂为氢型EWT结构分子筛,所述R-1为甲基、乙基、丙基、丁基或戊基,所述R-2为氢、甲基、乙基、丙基或丁基。该方法采用了氢型EWT结构的分子筛型催化剂,其具有更高的反应活性和更佳的缩醛收率。(The invention relates to the field of catalytic chemistry, and discloses a preparation method of 1, 1-dialkoxyalkane, wherein the preparation method comprises the following steps: in the presence of a catalyst, adding R 1 Alcohol of OH with R 2 -CHO, said catalyst is hydrogen type EWT structure molecular sieve, said R 1 Is methyl, ethyl, propyl, butyl or pentyl, said R 2 Hydrogen, methyl, ethyl, propyl or butyl. The method adopts a molecular sieve type catalyst with a hydrogen type EWT structure, and has higher reaction activity and better acetal yield.)

1. A process for the preparation of a1, 1-dialkoxyalkane, characterized in that the process comprises: in the presence of a catalyst, adding R₁Alcohols represented by-OH with R₂-contacting aldehyde represented by CHO, wherein the catalyst is a hydrogen type EWT structure molecular sieve; r₁Is C1-C5 alkyl, R₂Is hydrogen or C1-C4 alkyl.

2. The method of claim 1, wherein R₁Is methyl or ethyl, R₂Is methyl.

3. The production method according to claim 1 or 2, wherein the mass ratio of the catalyst to the raw material is 0.01 to 20:1, R₁Alcohols represented by-OH with R₂-CHO in a molar ratio of aldehyde of 0.5-5: 1.

4. The production method according to claim 3, wherein the mass ratio of the catalyst to the raw material is 0.1-5:1, R₁Alcohols represented by-OH with R₂-CHO with a molar ratio of aldehyde of 1-4: 1.

5. The production method according to claim 1, wherein the contact reaction conditions include: the reaction temperature is 20-170 ℃, and the reaction pressure is 0.01-8 MPa.

6. The production method according to claim 5, wherein the contact reaction conditions include: the reaction temperature is 30-130 ℃, and the reaction pressure is 0.1-3 MPa.

7. The production method according to any one of claims 1 to 6, wherein the silicon-aluminum ratio of the hydrogen-form EWT structure molecular sieve is 30 to 150: 1.

8. The preparation method of claim 7, wherein the silicon to aluminum ratio of the hydrogen-form EWT structure molecular sieve is 40-120: 1.

9. The production method according to any one of claims 1 to 8, wherein the production method of the hydrogen-type EWT-structure molecular sieve comprises: the raw powder of the EWT molecular sieve is subjected to ammonium exchange in an ammonium salt aqueous solution, dried and roasted.

10. The production method according to claim 9, wherein the temperature of ammonium exchange is 80 to 90 ℃, and the ammonium salt is selected from one or more of ammonium nitrate, ammonium chloride and ammonium sulfate; the roasting conditions comprise: the roasting temperature is 500-600 ℃, and the roasting time is 1-5 hours.

Technical Field

The invention relates to a catalytic chemistry technology, in particular to a preparation method of 1, 1-dialkoxyalkane.

Background

The EWT structure molecular sieve has a 3-dimensional 21-membered ring channel structure, is a first example synthesized silicon-aluminum molecular sieve with an ultra-large pore structure, has a stable structure, and can be industrially used for a reaction process of catalyzing and separating macromolecules. EWT structural molecular sieves were first synthesized by exxonmobil, usa. At present, the application of the EWT structure molecular sieve is rarely reported. CN109422627A discloses that a catalyst containing a molecular sieve with an EWT structure is applied to a catalytic reaction for preparing tert-butyl glyceryl ether by glycerol etherification. Specifically disclosed is a method for producing tert-butyl glyceryl ether by etherification of glycerin, which comprises subjecting glycerin and isobutylene to a contact reaction under etherification reaction conditions and in the presence of a glycerin etherification catalyst containing an EWT structure molecular sieve.

Acetal (1, 1-diethoxyethane) is a chemical synthesis intermediate, is used for protecting carbonyl in ketone and aldehyde, and can be used as solvent, fuel additive, food additive, perfume cosmetic raw material, etc. With the increasing demand of acetal, the development of the catalyst required for its preparation becomes more important. The synthesis of acetals is generally carried out under homogeneous catalytic conditions, for example, DE4404515A1, which uses liquid inorganic acids such as sulfuric acid and phosphoric acid as catalysts. Such catalysts are not suitable for large-scale industrial applications due to difficult separation and high corrosivity. The use of heterogeneous catalysts can effectively avoid the above problems. Article [ appl.catal.a General 2000, 198: L1-L4]It is reported that the yield of acetal in a catalytic cracking catalyst, i.e., a Y molecular sieve type catalyst, in a batch stirred reactor is about 15% at a reaction temperature of 20 ℃. CN102731273B discloses₁-CH-(OR₂)₂A process for the preparation of the acetals of the formula R₁-CH₂The alcohol shown as-OH is subjected to selective oxidation reaction or selective dehydrogenation reaction to obtain the formula R₁-aldehyde represented by CHO, R₂Alcohols represented by-OH with R₁-CHO aldehyde is subjected to condensation reaction under the action of acid catalyst, wherein R₁Is hydrogen, methyl, ethyl, propyl or butyl; r₂Is methyl, ethyl, propyl, butyl or pentyl. The catalyst of the selective oxidation reaction is an iron-molybdenum catalyst or a noble metal catalyst, and the selective dehydrogenation catalyst is a copper-silicon catalyst, a copper-chromium catalyst or a copper-zinc catalyst; the catalyst is Y-type molecular sieve, beta-type molecular sieve, ZSM-5 molecular sieve, mordenite molecular sieve, montmorillonite, solid super acid or solid acid. This procedure gave an acetal yield of 30%.

The above studies show that the yield of acetal is low when molecular sieves are used as catalysts.

Disclosure of Invention

The invention aims to provide a preparation method of 1, 1-dialkoxyalkane by taking a hydrogen-type EWT structure molecular sieve as a catalyst, which can effectively improve the yield of acetal generated by the reaction of alcohol and aldehyde.

In order to achieve the above object, the present invention provides a method for preparing a1, 1-dialkoxyalkane, wherein the method comprises: in the presence of a catalyst, adding R₁Alcohols represented by-OH with R₂-contacting aldehyde represented by CHO, wherein the catalyst is a hydrogen type EWT structure molecular sieve; r₁Is C1-C5 alkyl, R₂Is hydrogen or C1-C4 alkyl.

The inventor of the invention finds that compared with the conventional molecular sieve used as a catalyst for catalyzing alcohol to react with aldehyde to produce acetal, the molecular sieve with the hydrogen-type EWT structure used as the catalyst has obviously improved catalytic selectivity and greatly increased yield of acetal under the condition of equivalent conversion rate.

Preferably, the silicon to aluminum ratio of the hydrogen-form EWT structure molecular sieve is from 30 to 150:1, more preferably from 40 to 120: 1.

According to the invention, the hydrogen-type EWT-structure molecular sieve is used as a catalyst to catalyze the reaction of alcohol and aldehyde to produce acetal, and has a super-macroporous skeleton pore structure, good thermal/hydrothermal stability and larger pore volume, so that the hydrogen-type EWT-structure molecular sieve can adsorb more/larger molecules in the reaction of catalyzing the reaction of alcohol and aldehyde to produce acetal, and thus, the hydrogen-type EWT-structure molecular sieve has excellent adsorption/catalysis performance. Preferably, the hydrogen-form EWT-structure molecular sieve has unique Si/Al₂And (4) the ratio. Therefore, the temperature of the molten metal is controlled,the hydrogen-type EWT structure molecular sieve has more excellent performance particularly in acid catalytic reaction. Based on the above findings, the inventors further found that the molecular sieve L with such a structure has a larger number of acid centers, so that the catalytic conversion reaction of alcohol and aldehyde, such as the condensation reaction of ethanol and acetaldehyde, can be further improved, and a better yield of acetal can be obtained.

Drawings

FIG. 1 is an XRD pattern of hydrogen-form EWT structured molecular sieve catalyst A1 prepared from preparation example 1;

FIG. 2 is an XRD pattern of hydrogen-form EWT structured molecular sieve catalyst B1 prepared from preparative example 2.

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

Technical terms in the present invention are defined in the following, and terms not defined are understood in the ordinary sense in the art.

Unless otherwise expressly indicated, all percentages, parts, ratios, etc. mentioned in this specification are by weight unless otherwise not in accordance with the conventional knowledge of those skilled in the art.

According to the present invention, the method for preparing the 1, 1-dialkoxyalkane comprises: in the presence of a catalyst, adding R₁Alcohols represented by-OH with R₂-CHO and the catalyst is hydrogen type EWT structure molecular sieve.

According to the invention, R is in the presence of a catalyst₁Alcohols represented by-OH with R₂Condensation reaction of aldehyde represented by-CHO to obtain R₂-CH-(OR₁)₂Acetals, i.e., 1, 1-dialkoxyalkanes.

According to the invention, R₁The alcohol represented by-OH may be a monohydric alcohol conventionally used in the art, for example, R₁The alkyl group may be a C1-C5, specifically, a methyl group, an ethyl group, a propyl group, a butyl group or a pentyl group. Alcohol R₁Specific examples of-OH include, but are not limited to, methanol, ethanol, propanol, butanol, or pentanol.

According to the invention, R₂R in-CHO-expressing aldehyde₂It may be hydrogen or C1-C4 alkyl, specifically hydrogen, methyl, ethyl, propyl or butyl. Aldehyde R₂Specific examples of — CHO include, but are not limited to, formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde.

According to one embodiment of the invention, the catalytic system of the invention is more effective when it is applied to the preparation of 1, 1-diethoxyethane (acetal), and therefore preferably R1 is ethyl, i.e. R1 is ethyl₁OH is ethanol and R2 is methyl, i.e. R₂-CHO is acetaldehyde. That is, the present invention specifically provides a method for producing 1, 1-diethoxyethane (acetal), which comprises: in the presence of a catalyst, ethanol is in contact reaction with acetaldehyde, and the catalyst is a hydrogen-type EWT structure molecular sieve.

According to one embodiment of the invention, the catalytic system of the invention is suitable for the preparation of 1, 1-dimethoxyethane (hemiacetal) and is therefore able to exert its catalytic effect, and therefore preferably R1 is methyl, i.e. R1 is methyl₁OH is methanol and R2 is methyl, i.e. R₂-CHO is acetaldehyde. That is, the present invention specifically provides a method for producing 1, 1-dimethoxyethane (hemiacetal), which comprises: the methanol is contacted with acetaldehyde for reaction in the presence of a catalyst, wherein the catalyst is a hydrogen-type EWT structure molecular sieve.

Therefore, in particular, ethanol or methanol and acetaldehyde are reacted under the catalysis of the catalytic system of the invention, so that the selectivity and yield of the acetal or hemiacetal are more ideal.

According to the present invention, it is preferred that the hydrogen EWT-structured molecular sieve has a silica-alumina ratio of 30 to 150:1, more preferably 40 to 120:1, in terms of a molar ratio of silica to alumina, from the viewpoint of further improving the yield of acetal, particularly from the viewpoint of improving the yield of acetal or hemiacetal formed by reacting ethanol or methanol with acetaldehyde.

According to the present invention, the hydrogen-form EWT-structured molecular sieve can be obtained by a method well known to those skilled in the art. Specifically, the molecular sieve raw powder with the EWT structure can be obtained after ammonium exchange, drying and deamination roasting treatment. Wherein the ammonium exchange conditions comprise: the temperature may be from 0 to 100 deg.C, preferably from 80 to 90 deg.C. The water-soluble ammonium salt used for ammonium salt exchange may be selected from one or more of ammonium nitrate, ammonium chloride and ammonium sulfate. The concentration of the ammonium salt solution and the number and time of the ammonium exchange depend on the degree of exchange of sodium ions in the molecular sieve during actual operation, and for example, the concentration of the ammonium salt aqueous solution may be 0.1M to 0.5M. The solid-to-liquid ratio (ratio of molecular sieve to aqueous ammonium salt solution) (g/ml) of ammonium salt exchange is preferably 1:5 to 1: 10. The number of exchanges may be 1-3 and the time for each exchange may be 1-3 hours. The conditions of drying after ammonium exchange generally include a drying temperature, which may be 80 to 150 ℃, and a drying time, which may be selected depending on the temperature of calcination, and may generally be 12 to 20 hours. The conditions of the deamination roasting after drying generally comprise roasting temperature and roasting time, wherein the roasting temperature can be 500-600 ℃, and the roasting duration can be selected according to the roasting temperature and can be generally 1-10 hours, preferably 1-5 hours. The deamination calcination is generally carried out in an air atmosphere, which includes both a flowing atmosphere and a static atmosphere. Preferably, the ammonium exchange process further comprises solid-liquid separation after ammonium exchange and before drying, such as the steps of separating the molecular sieve from the filtrate and washing the molecular sieve. Specific filtration and washing methods are well known to those skilled in the art and will not be described in detail.

According to a specific embodiment of the present invention, the method for preparing the catalyst comprises: performing ammonium exchange on EWT molecular sieve raw powder in an ammonium salt aqueous solution at the temperature of 80-90 ℃, drying and roasting at the temperature of 500-600 ℃ for 1-5 hours; wherein the ammonium salt is selected from one or more of ammonium nitrate, ammonium chloride and ammonium sulfate.

According to the invention, the raw powder of the EWT structure molecular sieve can be obtained commercially or prepared according to the conventional method in the field, such as the method disclosed in CN 109422627A.

According to the invention, R₁Alcohols represented by-OH with R₂The conditions for the contact reaction of aldehyde represented by-CHO generally include a reaction temperature and a reaction pressure, wherein the reaction temperature is such that R is secured₁Alcohols represented by-OH with R₂The condensation reaction of — CHO can take place under catalysis of a catalyst, for example, the reaction temperature can be 20 to 170 ℃, preferably 30 to 130 ℃; in order to ensure the smooth progress of the condensation reaction, the reaction pressure may be maintained at 0.01 to 8MPa, preferably 0.1 to 3 MPa.

According to the present invention, although the object of the invention of increasing the yield of acetal can be achieved as long as the reaction is carried out under the catalytic system of the present invention, the mass ratio of the catalyst to the raw material is preferably 0.01 to 20:1, more preferably, the weight ratio of the catalyst to the raw material is 0.1 to 5:1, from the viewpoint of better achieving the object of the present invention. Wherein the raw material refers to R₁Alcohols represented by-OH with R₂-total amount of aldehydes expressed by CHO. Further preferably, R₁Alcohols represented by-OH with R₂The molar ratio of the aldehyde represented by-CHO may be 0.5 to 5:1, preferably, R₁Alcohols represented by-OH with R₂-CHO with a molar ratio of aldehyde of 1-4: 1.

In the process of the invention, from R₁Alcohols represented by-OH with R₂The reaction of the aldehyde represented by — CHO in the presence of a catalyst may be carried out in various reactors conventionally used in the art, for example, including, but not limited to, at least one of a tank reactor and a fixed bed reactor.

The present invention will be described in detail below by way of examples.

In the following preparations, XRD testing was performed using a Netherland, PANALYTICAL Corporation apparatus. And (3) testing conditions are as follows: cu target, Ka radiation, Ni filter, tube voltage of 40kV, tube current of 40mA, and scanning range of 4-50 deg.

In the following preparation examples, Nippon Denshi Motor Co., Ltd 30 was usedModel 13X-ray fluorescence spectrometer. And (3) testing conditions are as follows: tungsten target, excitation voltage 40kV, excitation current 50 mA. The experimental process comprises the following steps: the sample is pressed into a sheet and then arranged on an X-ray fluorescence spectrometer, and the sample emits fluorescence under the irradiation of X-rays, wherein the following relationship exists between the fluorescence wavelength lambda and the atomic number Z of the element: k (Z-S)²K is a constant, and as long as the wavelength λ of fluorescence is measured, the element can be identified. And measuring the intensity of each element characteristic spectral line by using a scintillation counter and a proportional counter, and carrying out element quantitative or semi-quantitative analysis.

In the following preparation examples, the total specific surface area, pore volume and pore diameter of the molecular sieve were measured according to the following analytical methods.

Equipment: micromeritic ASAP2010 static nitrogen adsorption instrument

Measurement conditions were as follows: putting the sample in a sample processing system, vacuumizing to 1.33 multiplied by 10 < -2 > Pa at 350 ℃, preserving heat and pressure for 15h, and purifying the sample. Measuring the P/P ratio of the purified sample at different specific pressures at a liquid nitrogen temperature of-196 DEG C₀And obtaining an adsorption-desorption isothermal curve for the adsorption quantity and the desorption quantity of the nitrogen under the condition. Then, the total specific surface area is calculated by utilizing a two-parameter BET formula, and the specific pressure P/P is taken₀The adsorption capacity of 0.98 or less is the pore volume of the sample, and the pore size distribution is calculated by a BJH model.

In the following examples, all reagents and starting materials are either commercially available or prepared according to established methods.

The reactant conversion, acetal selectivity and acetal yield were calculated from the following equations:

wherein n is the mass percentage of each component in the product.

The following preparation examples 1-2 are provided to illustrate the preparation of a hydrogen-type EWT structure molecular sieve.

The following examples 1-4 are presented to illustrate the process of preparing acetal by reacting ethanol with acetaldehyde, and example 5 is presented to illustrate the process of preparing acetal by reacting methanol with acetaldehyde.

Preparation example 1

23.35g of an aqueous solution of a template agent R (1, 5-bis (N-propylpyrrolidinium) pentane dihydroxide) (the content of R is 25% by mass) was charged into a 45mL polytetrafluoroethylene container, 1.25g of sodium metaaluminate and 7.67g of deionized water were added, stirred for 30 minutes until uniform, and then 9.64g of solid silica gel (SiO. RTM.) was added₂Content 93.37 mass%), stirring for 5 minutes and mixing fully, wherein the molar ratio of each component is as follows: SiO 2₂/Al₂O₃＝90、H₂O/SiO₂9.82, templating agent R/SiO₂＝0.15、OH^-/SiO₂＝0.08。

The above mixture was charged into a 45mL Teflon-lined steel autoclave which was covered and sealed, and the autoclave was placed in a rotating convection oven set at 20rpm and reacted at 150 ℃ for 5 days. And taking out the high-pressure autoclave, rapidly cooling the high-pressure autoclave to room temperature, separating the mixture on a high-speed centrifuge with the rpm of 5000, collecting solids, fully washing the solids with deionized water, and drying the solids for 5 hours at the temperature of 100 ℃ to obtain the raw powder of the molecular sieve with the EWT structure. Then, 0.5mol/L ammonium nitrate solution is used for ammonia exchange for 2 times at 80 ℃ and for 2 hours each time, and then the catalyst A1 of the hydrogen type EWT structure molecular sieve is prepared by washing with water, drying for 12 hours at 90 ℃ and roasting for 5 hours at 550 ℃.

The XRD pattern of the product is shown in figure 1, and the silicon-aluminum ratio of the hydrogen type EWT structure molecular sieve obtained by adopting X-ray fluorescence spectrum analysis is 91. The total specific surface area of the hydrogen-type EWT structure molecular sieve is S total 601m²(iv)/g, total pore volume Vtotal ═ 0.386cm³/g。

Preparation example 2

A raw powder of a molecular sieve having an EWT structure was prepared according to the method of preparation example 1, except that the amount of sodium metaaluminate charged was 2.24g, and the kinds and amounts of other materials were the same as those of preparation example 1The molar ratio of the components is as follows: SiO 2₂/Al₂O₃＝50、H₂O/SiO₂9.82, templating agent R/SiO₂＝0.15、OH^-/SiO₂0.08. Finally, the raw powder of the molecular sieve with the EWT structure is prepared. Catalyst B1 was prepared according to preparation example 1.

The XRD pattern of the product is shown in figure 2, and the silicon-aluminum ratio of the hydrogen type EWT structure molecular sieve obtained by adopting X-ray fluorescence spectrum analysis is 46. The total specific surface of the hydrogen-type EWT structure molecular sieve is S total 525m²(iv)/g, total pore volume Vtotal 0.352cm³/g。

Example 1

In a glove box under a nitrogen atmosphere, 5g of catalyst A1 of preparation example 1 was placed in a 100ml pressure reactor, and 41.31g of ethanol and 24.69g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 130 ℃ and after 3h of reaction the catalyst was separated from the product, the results of chromatographic analysis of the product are shown in Table 1.

Example 2

In a glove box under a nitrogen atmosphere, 5g of catalyst A1 of preparation example 1 was placed in a 100ml pressure reactor, and 44.65g of ethanol and 21.35g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 130 ℃ and after 3h of reaction the catalyst was separated from the product, the results of chromatographic analysis of the product are shown in Table 1.

Example 3

In a glove box under a nitrogen atmosphere, 5g of catalyst A1 of preparation example 1 was placed in a 100ml pressure reactor, and 20.29g of ethanol and 9.70g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 130 ℃ and after 3h of reaction the catalyst was separated from the product, the results of chromatographic analysis of the product are shown in Table 1.

Example 4

In a glove box under a nitrogen atmosphere, 5g of catalyst B1 of preparation example 2 was placed in a 100ml pressure reactor, and 20.29g of ethanol and 9.70g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 130 ℃ and after 3h of reaction the catalyst was separated from the product, the results of chromatographic analysis of the product are shown in Table 1.

Example 5

In a glove box under nitrogen atmosphere, 5g of catalyst A1 from example 1 was placed in a 100ml autoclave, and 44.65g of methanol and 15.35g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 30 ℃ and the catalyst was separated from the product after 3h of reaction, the results of chromatographic analysis of the product are shown in Table 1.

Comparative example 1

The hydrogen form of Beta molecular sieve (commercially available from Changling catalyst Mill) was designated AC 1.

In a glove box under nitrogen atmosphere, 5gAC1 was placed in a 100ml autoclave and 41.31g of ethanol and 24.69g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 130 ℃ and after 3h of reaction the catalyst was separated from the product, the results of chromatographic analysis of the product are shown in Table 1.

Comparative example 2

In a glove box under nitrogen atmosphere, 5gAC1 was placed in a 100ml autoclave and 44.65g of methanol and 15.35g of acetaldehyde were added. The pressure in the reactor was set to 3MPa, the temperature was 30 ℃ and the catalyst was separated from the product after 3h of reaction, the results of chromatographic analysis of the product are shown in Table 1.

TABLE 1

As can be seen from the results in table 1, in example 1 and comparative example 1, the hydrogen EWT molecular sieve shows higher acetal selectivity and yield compared to Beta molecular sieve with hydrogen EWT structure molecular sieve under the same catalyst conditions. Example 5 and comparative example 2 are the results of using a hydrogen EWT structure molecular sieve compared to Beta molecular sieve under the same catalyst conditions, the hydrogen EWT molecular sieve exhibits higher hemiacetal selectivity and yield.

Further, as can be seen from the results of the evaluation of the reaction with the catalysts of examples 1 to 3, under the same catalyst conditions, the reaction conditions were optimized to further improve the yield of acetal. Evaluation of the catalysts of examples 3 to 4 revealed that the yield of acetal was further improved by increasing the silica/alumina ratio of the molecular sieve having a hydrogen-type EWT structure under the same reaction conditions.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.