CN106966862B

CN106966862B - Method for simultaneously preparing propylene glycol and propylene carbonate

Info

Publication number: CN106966862B
Application number: CN201610022721.1A
Authority: CN
Inventors: 林民; 史春风; 朱斌
Original assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Current assignee: Sinopec Research Institute of Petroleum Processing; China Petroleum and Chemical Corp
Priority date: 2016-01-14
Filing date: 2016-01-14
Publication date: 2021-03-12
Anticipated expiration: 2036-01-14
Also published as: CN106966862A

Abstract

The invention relates to the field of fine chemical engineering, and particularly provides a method for simultaneously preparing propylene glycol and propylene carbonate, which comprises the following steps: (1) under the condition of epoxidation, propylene is oxidized to prepare propylene oxide; (2) the propylene oxide, water and CO obtained in the step (1) are mixed₂Contacting with a catalyst A, wherein the catalyst A comprises a titanium silicalite molecular sieve containing a template agent. The method of the invention uses the titanium silicalite molecular sieve containing the template agent as the template agent prepared from propylene oxide, water and CO₂The catalyst for preparing the propylene glycol and the propylene carbonate can obtain high propylene oxide conversion rate and propylene glycol and propylene carbonate selectivity even if the reaction is carried out at a lower reaction temperature (such as not higher than 160 ℃ and even not higher than 120 ℃).

Description

Method for simultaneously preparing propylene glycol and propylene carbonate

Technical Field

The invention relates to a method for simultaneously preparing propylene glycol and propylene carbonate.

Background

Propylene Glycol (PG), also known as propylene glycol, and commonly known as 1, 2-propanediol, is an important raw material for the preparation of unsaturated polyesters, which are used in large quantities in surface coatings and reinforced plastics, epoxy resins and polyurethane resins. Propylene glycol is excellent in viscosity and hygroscopicity and is non-toxic, and thus is widely used as a moisture absorbent, an anti-freezing agent, a lubricant and a solvent in the food, pharmaceutical and cosmetic industries. In the food industry, propylene glycol reacts with fatty acids to form propylene glycol fatty acid esters, which are mainly used as food emulsifiers; meanwhile, propylene glycol is also an excellent solvent for seasonings and pigments. Propylene glycol is commonly used in the pharmaceutical industry as a solvent, softener, excipient, etc. for various ointments and salves, and also as a solvent, softener, etc. for cosmetics because of its good miscibility with various fragrances. Propylene glycol is also used as a tobacco humectant, mold inhibitor, lubricant for food processing equipment, and solvent for food marking inks.

In the prior art, propylene glycol is produced primarily by the reconversion of propylene oxide, typically at 180-220 ℃ and 15-25 bar, while large amounts of water must be employed to inhibit the production of polyethylene glycol. For example, CN1768027A discloses a process for preparing propylene glycol from propylene oxide by first contacting propylene oxide with carbon dioxide in the substantial absence of water to form a propylene carbonate intermediate; then, the propylene carbonate is contacted with water to react to obtain propylene glycol.

The propylene carbonate is not only an aprotic organic solvent with excellent performance, high boiling point and high polarity, but also an important organic synthesis intermediate. Propylene carbonate has been widely used as an electrolyte for capacitors and high-energy batteries, a desulfurization and decarburization solvent, a metal extractant, a binder, a plasticizer for polymers, and the like; in addition, the propylene carbonate can also be used for synthesizing important fine chemical products such as dimethyl carbonate and the like.

At present, the industrial production method of propylene carbonate comprises the following steps: phosgene process, transesterification process, chloropropanol process, and cycloaddition of propylene oxide and carbon dioxide. Among them, the cycloaddition method of propylene oxide and carbon dioxide is gradually becoming the main production method of propylene carbonate due to its advantages of high atom utilization rate (100%), simple process, environmental protection, etc.

In the process of synthesizing propylene carbonate by cycloaddition of propylene oxide and carbon dioxide, the commonly used catalysts comprise: (1) homogeneous catalyst: quaternary ammonium salts, quaternary ammonium bases, organic phosphine compounds, organometallic compounds, alkali metal or alkaline earth metal halides, and the like; (2) heterogeneous catalyst: metal oxides or mixtures thereof, molecular sieves, supported catalysts, and the like. Among them, the molecular sieve has the advantages of regular and ordered pore channels, large specific surface area, stable structure and the like, and is widely applied to oil refining process and chemical product production. However, in the process of synthesizing propylene carbonate by cycloaddition method, the activity of the molecular sieve is very poor. Therefore, the literature reports that molecular sieves are generally modified to increase their activity using quaternary ammonium salts, quaternary ammonium bases, ionic liquids, or the like. Although the quaternary ammonium salt, quaternary ammonium base or ionic liquid is used for modifying the molecular sieve to effectively improve the activity of the molecular sieve in the cycloaddition method, the method needs the steps of roasting, modification, secondary modification and the like, so that the method for fixing the active component on the outer surface of the molecular sieve has the defects of high energy consumption, complex process, environmental friendliness (benzene, toluene and the like are used as solvents in the modification) and the like. Therefore, it is necessary to explore more environment-friendly and efficient molecular sieve catalysts to develop the application of molecular sieves in the preparation of propylene carbonate by cycloaddition.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a method for simultaneously preparing propylene glycol and propylene carbonate, which can obtain higher propylene oxide conversion rate and propylene glycol and propylene carbonate selectivity even under relatively mild reaction conditions (such as the temperature of no higher than 160 ℃).

The inventor of the present invention found in the research process that in the process of preparing propylene glycol by hydrolyzing propylene oxide, the titanium silicalite molecular sieve containing the template agent is used as the catalyst, so that the conversion rate of propylene oxide and the selectivity of the target product can be effectively improved. It has been found more surprisingly that in the preparation of propylene glycol, if propylene oxide and water are mixed with CO₂The reaction temperature can be effectively reduced, the conversion rate of the propylene oxide can be obviously improved, and the propylene carbonate can be particularly co-produced. The present invention has been completed based on this finding.

To achieve the foregoing object, the present invention provides a method for simultaneously preparing propylene glycol and propylene carbonate, the method comprising: (1) under the condition of epoxidation, propylene is oxidized to prepare propylene oxide;

(2) the propylene oxide, water and CO obtained in the step (1) are mixed₂Contacting with a catalyst A, wherein the catalyst A comprises a titanium silicalite molecular sieve containing a template agent.

In the synthesis process of the titanium silicalite molecular sieve, the organic template plays a very important role, but in general, the template needs to be removed from the main pore channels of the molecular sieve before use (for example, the synthesized titanium silicalite molecular sieve is calcined) to realize the catalytic or adsorption performance of the molecular sieve. The method of the invention uses the titanium silicalite molecular sieve containing the template agent as the catalyst for preparing propylene glycol and propylene carbonate from propylene oxide, and can obtain high propylene oxide conversion rate and propylene glycol and propylene carbonate selectivity even if the reaction is carried out at a lower reaction temperature (such as not higher than 160 ℃ and even not higher than 120 ℃).

The method of the invention develops the new application of the titanium-silicon molecular sieve, in particular to the molecular sieve with the pore channel containing the structure directing agent. In addition, the method of the invention is simple and easy to implement, and if the method is carried out in an autoclave type reactor, the molecular sieve can be separated from the liquid phase mixture containing the propylene glycol and the propylene carbonate only by a solid-liquid separation method such as filtration.

In a preferred embodiment of the present invention, propylene oxide is produced according to the process of the present invention, not only is the propylene conversion high, but also the catalyst has a long life, can be operated for a long time, and has a high propylene oxide yield.

Additional features and advantages of the invention will be set forth in the detailed description which follows.

Detailed Description

The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.

The invention provides a method for simultaneously preparing propylene glycol and propylene carbonate, which comprises the following steps: (1) under the condition of epoxidation, propylene is oxidized to prepare propylene oxide; (2) the propylene oxide, water and CO obtained in the step (1) are mixed₂Contacting with a catalyst A, wherein the catalyst A comprises a titanium silicalite molecular sieve containing a template agent.

According to the process of the present invention, it is preferred that in the step (1), propylene is oxidized to produce propylene oxide as follows: in the presence of a solvent, propylene is contacted with hydrogen peroxide and a catalyst B, wherein the catalyst B contains a titanium silicalite molecular sieve, and propylene oxide is obtained by separation.

According to the process of the present invention, preferably, the solvent in step (1) is methanol.

According to the process of the present invention, in step (1), the hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art. From the viewpoint of further improving safety, the process according to the invention preferably uses hydrogen peroxide in the form of an aqueous solution. According to the process of the invention, when the hydrogen peroxide is provided in the form of an aqueous solution, the concentration of the aqueous hydrogen peroxide solution may be a concentration conventional in the art, for example: 20-80 wt%. Aqueous solutions of hydrogen peroxide at concentrations meeting the above requirements may be prepared by conventional methods or may be obtained commercially, for example: can be 30 percent by weight of hydrogen peroxide, 50 percent by weight of hydrogen peroxide or 70 percent by weight of hydrogen peroxide which can be obtained commercially.

According to the method of the present invention, the catalyst B in step (1) may be a shaped or unshaped catalyst containing the titanium silicalite.

According to the method of the present invention, the titanium silicalite molecular sieve in the catalyst B in step (1) may be a titanium silicalite molecular sieve commonly used in the art (the titanium silicalite molecular sieve refers to a templating agent-free titanium silicalite molecular sieve, and the content of the templating agent is less than 0.1 wt%), and for example, the titanium silicalite molecular sieve may be a common titanium silicalite molecular sieve with various topologies, such as: the titanium silicalite molecular sieve can be one or more of a titanium silicalite molecular sieve with an MFI structure (such as TS-1), a titanium silicalite molecular sieve with an MEL structure (such as TS-2), a titanium silicalite molecular sieve with a BEA structure (such as Ti-Beta), a titanium silicalite molecular sieve with an MWW structure (such as Ti-MCM-22), a titanium silicalite molecular sieve with an MOR structure (such as Ti-MOR), a titanium silicalite molecular sieve with a TUN structure (such as Ti-TUN), a titanium silicalite molecular sieve with a two-dimensional hexagonal structure (such as Ti-MCM-41 and Ti-SBA-15) and a titanium silicalite molecular sieve with other structures (such as Ti-ZSM-48). The titanium silicalite molecular sieve is preferably one or more of a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure and a titanium silicalite molecular sieve with a BEA structure, and more preferably is a titanium silicalite molecular sieve with an MFI structure.

According to the process of the present invention, it is preferred that in step (1), the molar ratio of propylene, solvent (e.g., methanol) and hydrogen peroxide is in the range of from 0.1 to 10:1 to 100:1, more preferably in the range of from 1 to 5:5 to 20: 1.

According to the method of the invention, in the step (1), the weight ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.1-500; in a slurry bed reactor, the concentration of the titanium silicalite molecular sieve is 0.002-0.1g/mL, specifically, the dosage of the titanium silicalite molecular sieve is 0.002-0.1g per mL of reaction material.

According to the method of the present invention, it is preferable that in the step (1), the contacting conditions include: the temperature is 0-80 ℃, the pressure is 0.1-2MPa, and the time is 0.1-4 h; more preferably at a temperature of 20-60 deg.C, a pressure of 0.1-1.5MPa, and a time of 0.2-1 h.

According to the method of the present invention, in the catalyst B, at least a part of the titanium silicalite molecular sieves is a modified titanium silicalite molecular sieves, and the modified titanium silicalite molecular sieves are titanium silicalite molecular sieves subjected to modification treatment, wherein the modification treatment comprises contacting the titanium silicalite molecular sieves serving as a raw material with a modification liquid containing nitric acid and at least one peroxide.

The titanium silicalite as a raw material is a titanium silicalite as a raw material for modification treatment, and may be a titanium silicalite which has not been subjected to the modification treatment or a titanium silicalite which has been subjected to the modification treatment but needs to be subjected to the modification treatment again.

According to the method of the present invention, in the catalyst B, all the titanium silicalite molecular sieves may have been subjected to the above modification treatment (i.e., the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves), or some of the titanium silicalite molecular sieves may have been subjected to the above modification treatment (i.e., the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves and unmodified titanium silicalite molecular sieves). Preferably, in the catalyst B, at least 50 wt% or more of the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves, more preferably at least 60 wt% or more of the titanium silicalite molecular sieves are modified titanium silicalite molecular sieves, for example, the content of the modified titanium silicalite molecular sieves may be 5 to 95 wt%, preferably 20 to 90 wt%, more preferably 40 to 80 wt%, based on the total amount of the titanium silicalite molecular sieves.

In the modification treatment, the peroxide may be selected from hydrogen peroxide, hydroperoxide and peracid. In the present invention, hydroperoxide means a substance obtained by substituting one hydrogen atom in a hydrogen peroxide molecule with an organic group, and peracid means an organic oxygen acid having an-O-bond in its molecular structure.

In the modification treatment, specific examples of the peroxide may include, but are not limited to: hydrogen peroxide, ethylbenzene hydroperoxide, tert-butyl hydroperoxide, cumene hydroperoxide, cyclohexyl hydroperoxide, peracetic acid and propionic acid. Preferably, the peroxide is hydrogen peroxide. The hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art.

In the modification treatment, the molar ratio of the titanium silicalite molecular sieve as the raw material to the peroxide may be 1: 0.01 to 5, preferably 1: 0.05 to 3, more preferably 1: 0.1-2. The amount of nitric acid may be selected based on the amount of peroxide. Generally, the molar ratio of the peroxide to the nitric acid may be 1: 0.01 to 50, preferably 1:0.1 to 20, more preferably 1: 0.2 to 10, more preferably 1: 0.5 to 5, particularly preferably 1: 0.6-3.5, such as 1: 0.7-1.2, wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.

In the modification liquid, the concentrations of the peroxide and the nitric acid may be 0.1 to 50% by weight, respectively. From the viewpoint of further improving the catalytic performance of the finally prepared modified titanium silicalite molecular sieve, it is preferably 0.5 to 25 wt%. More preferably, the concentrations of the peroxide and the nitric acid in the modification liquid are each 5 to 15% by weight.

The solvent of the modifying solution can be various common solvents capable of dissolving the nitric acid and the peroxide at the same time. Preferably, the solvent of the modifying solution is water.

In the modification treatment, the titanium silicalite molecular sieve as the raw material and the modification solution can be contacted at the temperature of 10-350 ℃. The contacting is preferably carried out at a temperature of 20 to 300 deg.c from the viewpoint of further improving the catalytic performance of the finally prepared modified titanium silicalite. More preferably, the contacting is carried out at a temperature of 50-250 ℃. Further preferably, the contacting is performed at a temperature of 60-200 ℃. Even more preferably, the contacting is carried out at a temperature of 70-150 ℃. The duration of the contact may be from 1 to 10h, preferably from 3 to 5 h. In the modification treatment, the pressure in the vessel in which the titanium silicalite molecular sieve as the raw material is brought into contact with the modification solution may be selected depending on the contact temperature, and may be either ambient pressure or pressurized. Generally, the pressure in the vessel in which the titanium silicalite molecular sieve as the raw material is contacted with the modifying liquid may be 0 to 5MPa, and the pressure is a gauge pressure. Preferably, the titanium silicalite molecular sieve as the raw material is contacted with the modifying liquid under the condition of pressurization. More preferably, the titanium silicalite molecular sieve as the raw material is contacted with the modifying liquid under autogenous pressure in a closed container.

In the modification treatment, the contact degree between the titanium silicalite molecular sieve as the raw material and the modification liquid is preferably such that, based on the titanium silicalite molecular sieve as the raw material, in an ultraviolet-visible spectrum, the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230 nm and 310nm is reduced by more than 2%, and the pore volume of the modified titanium silicalite molecular sieve is reduced by more than 1%. The peak area of the absorption peak of the modified titanium-silicon molecular sieve between 230-310nm is preferably reduced by 2-30%, more preferably reduced by 2.5-15%, still more preferably reduced by 3-10%, and still more preferably reduced by 3-6%. The pore volume of the modified titanium silicalite molecular sieve is preferably reduced by 1 to 20%, more preferably by 1.5 to 10%, and even more preferably by 2 to 5%. The pore volume is determined by a static nitrogen adsorption method.

According to the method, in the catalyst B, at least part of the titanium silicalite molecular sieve is preferably the titanium silicalite molecular sieve TS-1, the surface silicon-titanium ratio of the titanium silicalite molecular sieve TS-1 is not lower than the bulk silicon-titanium ratio, so that the effective utilization rate of an oxidant can be further improved, and the one-way service life of the titanium silicalite molecular sieve can be further prolonged, wherein the silicon-titanium ratio refers to the molar ratio of silicon oxide to titanium oxide, the surface silicon-titanium ratio is determined by adopting an X-ray photoelectron spectroscopy method, and the bulk silicon-titanium ratio is determined by adopting an X-ray fluorescence spectroscopy method;

preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.2 or more;

more preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.2-5;

further preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.5-4.5.

According to the method of the present invention, in the catalyst B, at least a part of the titanium silicalite molecular sieve is the titanium silicalite molecular sieve TS-1, and the titanium silicalite molecular sieve TS-1 is prepared by a method comprising the following steps:

(A) dispersing an inorganic silicon source in an aqueous solution containing a titanium source and an alkali source template agent, and optionally supplementing water to obtain a dispersion liquid, wherein the ratio of the silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: (0.5-8): (5-30): (100-2000), the inorganic silicon source is SiO₂The titanium source is calculated as TiO₂The alkali source template is counted as OH^-Or N (when the alkali source template contains nitrogen element, the amount is counted by N; when the alkali source template does not contain nitrogen element, the amount is counted by OH^-A meter);

(B) optionally, standing the dispersion at 15-60 ℃ for 6-24 h;

(C) and (3) sequentially carrying out stage (1), stage (2) and stage (3) crystallization on the dispersion liquid obtained in the step (A) or the dispersion liquid obtained in the step (B) in a sealed reaction kettle, wherein the stage (1) is crystallized for 6-72 hours at the temperature of 80-150 ℃, the stage (2) is cooled to the temperature of not higher than 70 ℃ and the retention time is at least 0.5 hour, and then the stage (3) is heated to the temperature of 120-200 ℃ for recrystallization for 6-96 hours.

In the present invention, "optionally" means optionally, and may be understood as "containing or not containing" and "including or not including".

The alkali source template can be various templates commonly used in the process of synthesizing the titanium silicalite molecular sieve, such as: the alkali source template agent can be one or more than two of quaternary ammonium base, aliphatic amine and aliphatic alcohol amine. The quaternary ammonium base can be various organic quaternary ammonium bases, and the aliphatic amine can be various NH₃In which at least one hydrogen is substituted with an aliphatic hydrocarbon group (e.g., an alkyl group), which may be a variety of NH₃Wherein at least one hydrogen is replaced by a hydroxyl-containing aliphatic group (e.g.Alkyl) substituted.

Specifically, the alkali source template may be one or more selected from the group consisting of a quaternary ammonium base represented by formula I, an aliphatic amine represented by formula II, and an aliphatic alcohol amine represented by formula III.

In the formula I, R₁、R₂、R₃And R₄Each is C₁-C₄Alkyl of (2) including C₁-C₄Straight chain alkyl of (2) and C₃-C₄Branched alkyl of R₁、R₂、R₃And R₄Specific examples of (a) may include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl.

R⁵(NH₂)_n(formula II)

In the formula II, n is an integer of 1 or 2. When n is 1, R⁵Is C₁-C₆Alkyl of (2) including C₁-C₆Straight chain alkyl of (2) and C₃-C₆Specific examples of the branched alkyl group of (a) may include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl and n-hexyl. When n is 2, R⁵Is C₁-C₆Alkylene of (2) including C₁-C₆Linear alkylene of (A) and (C)₃-C₆Specific examples thereof may include, but are not limited to, methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene.

(HOR⁶)_mNH_(3-m)(formula III)

In the formula III, m R⁶Are the same or different and are each C₁-C₄Alkylene of (2) including C₁-C₄Linear alkylene of (A) and (C)₃-C₄Specific examples of the branched alkylene group of (1) may include, but are not limited to, methyleneAlkyl, ethylene, n-propylene and n-butylene; m is 1,2 or 3.

Specific examples of the alkali-derived templating agent may include, but are not limited to: one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide (including various isomers of tetrapropylammonium hydroxide such as tetra-n-propylammonium hydroxide and tetraisopropylammonium hydroxide), tetrabutylammonium hydroxide (including various isomers of tetrabutylammonium hydroxide such as tetra-n-butylammonium hydroxide and tetraisobutylammonium hydroxide), ethylamine, n-propylamine, n-butylamine, di-n-propylamine, butanediamine, hexanediamine, monoethanolamine, diethanolamine, and triethanolamine. Preferably, the alkali source template is one or more of tetraethylammonium hydroxide, tetrapropylammonium hydroxide and tetrabutylammonium hydroxide. More preferably, the alkali-source templating agent is tetrapropylammonium hydroxide.

The titanium source may be an inorganic titanium salt and/or an organic titanate, preferably an organic titanate. The inorganic titanium salt may be TiCl₄、Ti(SO₄)₂And TiOCl₂One or more than two of the above; the organic titanate may be of the formula R⁷ ₄TiO₄A compound of wherein R⁷Is an alkyl group having 1 to 6 carbon atoms, preferably an alkyl group having 2 to 4 carbon atoms.

The inorganic silicon source can be silica gel and/or silica sol, and silica gel is preferred. SiO in the silica sol₂The content of (b) may be 10% by mass or more, preferably 15% by mass or more, and more preferably 20% by mass or more. In preparing the titanium silicalite molecular sieves according to this preferred embodiment, no source of organic silicon, such as organosilanes and organosiloxanes, is used.

In the dispersion, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is preferably 100: (1-6): (8-25): (200-1500), more preferably 100: (2-5): (10-20): (400-1000).

The dispersion obtained in step (A) may be directly fed to step (C) for crystallization. Preferably, the dispersion obtained in step (A) is fed to step (B) and allowed to stand at a temperature of 15 to 60 ℃ for 6 to 24 hours. The step (B) between the step (A) and the step (C) can obviously improve the surface silicon-titanium ratio of the finally prepared titanium-silicon molecular sieve TS-1, so that the surface silicon-titanium ratio of the finally prepared titanium-silicon molecular sieve is not lower than the bulk silicon-titanium ratio, the catalytic performance of the finally prepared titanium-silicon molecular sieve can be obviously improved, the one-way service life of the finally prepared titanium-silicon molecular sieve is prolonged, and the effective utilization rate of an oxidant is improved. Generally, by placing step (B) between step (a) and step (C), the ratio of surface silicon to titanium to bulk silicon to titanium of the finally prepared titanium silicalite molecular sieve can be in the range of 1.2 to 5, preferably in the range of 1.5 to 4.5 (e.g., in the range of 2.5 to 4.5), more preferably in the range of 2 to 3. More preferably, the standing is carried out at a temperature of 20-50 deg.C, such as 25-45 deg.C.

In the step (B), the dispersion may be placed in a sealed container or may be placed in an open container and allowed to stand. Preferably, step (B) is carried out in a sealed vessel, so that introduction of external impurities into the dispersion during standing or volatilization loss of a part of the substance in the dispersion can be avoided.

After the standing in the step (B) is finished, the standing dispersion liquid can be directly sent into a reaction kettle for crystallization, or the standing dispersion liquid can be sent into the reaction kettle for crystallization after being redispersed, and preferably sent into the reaction kettle after being redispersed, so that the dispersion uniformity of the crystallized dispersion liquid can be further improved. The method of redispersion may be a conventional method such as one or a combination of two or more of stirring, sonication, and shaking. The duration of the redispersion is such that a homogeneous dispersion is formed from the dispersion on standing, and may generally be from 0.1 to 12 hours, for example from 0.5 to 2 hours. The redispersion can be carried out at ambient temperature, for example at a temperature of from 15 to 40 ℃.

In the step (C), the temperature increase rate and the temperature decrease rate for adjusting the temperature to each stage may be selected according to the type of the crystallization reactor specifically used, and are not particularly limited. In general, the rate of temperature increase to raise the temperature to the crystallization temperature of stage (1) may be from 0.1 to 20 deg.C/min, preferably from 0.1 to 10 deg.C/min, more preferably from 1 to 5 deg.C/min. The rate of temperature decrease from the stage (1) temperature to the stage (2) temperature may be from 1 to 50 deg.C/min, preferably from 2 to 20 deg.C/min, more preferably from 5 to 10 deg.C/min. The rate of temperature increase from the stage (2) temperature to the stage (3) crystallization temperature may be 1 to 50 ℃/min, preferably 2 to 40 ℃/min, more preferably 5 to 20 ℃/min.

In the step (C), the crystallization temperature in the stage (1) is preferably 110-. The crystallization time of stage (1) is preferably 6 to 24h, more preferably 6 to 8 h. The temperature of the stage (2) is preferably not higher than 50 ℃. The residence time of stage (2) is preferably at least 1h, more preferably from 1 to 5 h. The crystallization temperature of stage (3) is preferably 140-. The crystallization time of stage (3) is preferably 12-20 h.

In step (C), in a preferred embodiment, the crystallization temperature in stage (1) is lower than that in stage (3), so as to further improve the catalytic performance of the prepared titanium silicalite molecular sieve. Preferably, the crystallization temperature of stage (1) is 10-50 ℃ lower than the crystallization temperature of stage (3). More preferably, the crystallization temperature of stage (1) is 20-40 ℃ lower than the crystallization temperature of stage (3). In step (C), in another preferred embodiment, the crystallization time in stage (1) is shorter than that in stage (3), so as to further improve the catalytic performance of the finally prepared titanium silicalite molecular sieve. Preferably, the crystallization time of stage (1) is 5-24h shorter than the crystallization time of stage (3). More preferably, the crystallization time of stage (1) is 6-12h, such as 6-8h shorter than the crystallization time of stage (3). In step (C), these two preferred embodiments may be used alone or in combination, preferably in combination, that is, the crystallization temperature and crystallization time of stage (1) and stage (3) satisfy the requirements of these two preferred embodiments at the same time.

In step (C), in another preferred embodiment, the temperature of stage (2) is not higher than 50 ℃, and the residence time is at least 0.5h, such as 0.5-6h, so as to further improve the catalytic performance of the finally prepared titanium silicalite molecular sieve. Preferably, the residence time of stage (2) is at least 1h, such as 1-5 h. This preferred embodiment can be used separately from the two preferred embodiments described above, or in combination, preferably in combination, i.e. the crystallization temperature and crystallization time of stage (1) and stage (3) and the temperature and residence time of stage (2) simultaneously meet the requirements of the three preferred embodiments described above.

Conventional methods can be used to recover the titanium silicalite from the mixture crystallized in step (C). Specifically, after optionally filtering and washing the mixture obtained by crystallization in step (C), the solid matter may be dried and calcined to obtain the titanium silicalite molecular sieve. The drying and the firing may be performed under conventional conditions. Generally, the drying may be carried out at a temperature of from ambient temperature (e.g., 15 ℃) to 200 ℃. The drying may be carried out at ambient pressure (typically 1 atm), or under reduced pressure. The duration of the drying may be selected according to the temperature and pressure of the drying and the manner of the drying, and is not particularly limited. For example, when the drying is carried out at ambient pressure, the temperature is preferably 80 to 150 ℃, more preferably 100 ℃ to 120 ℃, and the duration of the drying is preferably 0.5 to 5 hours, more preferably 1 to 3 hours. The calcination may be carried out at a temperature of 300-800 ℃, preferably at a temperature of 500-700 ℃, more preferably at a temperature of 550-650 ℃, and even more preferably at a temperature of 550-600 ℃. The duration of the calcination may be selected according to the temperature at which the calcination is carried out, and may generally be 2 to 12 hours, preferably 2 to 5 hours. The calcination is preferably carried out in an air atmosphere.

According to the method of the present invention, the content of the template-containing titanium silicalite molecular sieve in the catalyst a is preferably 50 wt% or more, and more preferably, the content of the template-containing titanium silicalite molecular sieve in the catalyst a is 60 to 100 wt%. In the specific embodiment of the present invention, catalyst a with a template-containing titanium silicalite molecular sieve content of 100 wt% is used, but this does not limit the scope of the present invention. The content herein refers to the composition of the catalyst without a support.

When the catalyst A or the catalyst B is a molded body, the catalyst A or the catalyst B further comprises a carrier, wherein each carrier may be Al₂O₃、ZnO、MgO、SiO₂CaO and TiO₂Rare earth oxide RE₂O₃(RE is rare earth elements such as La, Ce, Y or Nd).

In the present invention, the template-containing titanium silicalite molecular sieve refers to a titanium silicalite molecular sieve containing the template agent remaining in the synthesis process, that is: the titanium silicalite is not subjected to a process of removing the templating agent after synthesis, or even if the titanium silicalite is subjected to a process of removing the templating agent, the templating agent is not completely removed.

The content of the templating agent in the titanium silicalite molecular sieve containing the templating agent is not particularly limited, and can be selected according to the type of the titanium silicalite molecular sieve and the specific contact conditions. Generally, the content of the template in the titanium silicalite molecular sieve can be 0.1 to 25 weight percent. Preferably, the content of the template in the titanium-silicon molecular sieve is 1-20 wt%, and more preferably 5-15 wt%. The content of the template can be determined by a thermogravimetric analysis method, and generally, the weight loss percentage between 200 ℃ and 800 ℃ in the thermogravimetric analysis can be used as the content of the template.

The template agent can be various template agents commonly used in the process of synthesizing the titanium silicalite molecular sieve, such as: the templating agent may be one or more of a quaternary ammonium base, an aliphatic amine, and an aliphatic alcohol amine. The quaternary ammonium base can be various organic quaternary ammonium bases, and the aliphatic amine can be various NH₃In which at least one hydrogen is substituted with an aliphatic hydrocarbon group (e.g., an alkyl group), which may be a variety of NH₃Wherein at least one hydrogen is substituted with a hydroxyl-containing aliphatic group (e.g., an alkyl group).

The quaternary ammonium base, the aliphatic amine and the aliphatic alcohol amine have been described in detail hereinbefore. The description is not repeated here.

For the present invention, the preferred templating agent in the titanium silicalite molecular sieve containing the templating agent may be, but is not limited to: one or more of tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide (including various isomers of tetrapropylammonium hydroxide, such as tetra-n-propylammonium hydroxide and tetraisopropylammonium hydroxide), tetrabutylammonium hydroxide (including various isomers of tetrabutylammonium hydroxide, such as tetra-n-butylammonium hydroxide and tetraisobutylammonium hydroxide), ethylamine, n-propylamine, n-butylamine, di-n-propylamine, butanediamine, hexanediamine, monoethanolamine, diethanolamine, and triethanolamine. Preferably, the templating agent is tetraethylammonium hydroxide, tetrapropylammonium hydroxide, and tetrabutylammonium hydroxide.

According to the method of the present invention, the titanium silicalite molecular sieve in the template-containing titanium silicalite molecular sieve can be common titanium silicalite molecular sieves with various topologies, such as: the titanium silicalite molecular sieve can be selected from titanium silicalite molecular sieve with MFI structure (such as TS-1), titanium silicalite molecular sieve with MEL structure (such as TS-2), titanium silicalite molecular sieve with BEA structure (such as Ti-Beta), titanium silicalite molecular sieve with MWW structure (such as Ti-MCM-22), titanium silicalite molecular sieve with MOR structure (such as Ti-MOR), titanium silicalite molecular sieve with TUN structure (such as Ti-TUN), titanium silicalite molecular sieve with two-dimensional hexagonal structure (such as Ti-MCM-41 and Ti-SBA-15), titanium silicalite molecular sieve with other structure (such as Ti-ZSM-48), etc. The titanium silicalite molecular sieve is preferably selected from a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure and a titanium silicalite molecular sieve with a BEA structure, and more preferably is a titanium silicalite molecular sieve with an MFI structure.

From the perspective of further improving the conversion rate of propylene oxide and the selectivity of propylene glycol and propylene carbonate, the titanium silicalite molecular sieve is a hollow titanium silicalite molecular sieve with an MFI structure, crystal grains of the hollow titanium silicalite molecular sieve are of a hollow structure, the radial length of a cavity part of the hollow structure is 5-300nm, and after a template agent is removed from the hollow titanium silicalite molecular sieve, the hollow titanium silicalite molecular sieve is subjected to P/P reaction at 25 DEG C₀The benzene adsorption amount measured under the conditions of 0.10 and the adsorption time of 1h is at least 70mg/g, and a hysteresis loop exists between the adsorption isotherm and the desorption isotherm of low-temperature nitrogen adsorption. Hollow titanium silicalite molecular sieves containing templating agents can be prepared according to the method disclosed in CN1132699C, except that the final calcination step aimed at removing the templating agent is not performed.

According to the method of the invention, in the step (2), the catalyst A is used in an amount capable of realizing a catalytic function. In general, the weight ratio of propylene oxide to the catalyst a may be from 0.1 to 100:1, preferably 0.5 to 100: 1.

according to the process of the present invention, in step (2), the contacting is preferably carried out in the presence of a solvent, which can be further enhancedThe mixing degree of each reactant in the reaction system enhances the diffusion and more conveniently adjusts the reaction intensity. The kind of the solvent is not particularly limited. In general, the solvent may be selected from C₃-C₈The ketone or halogenated alkane of (2) is preferably C₁-C₄And C₂-C₈One or more of (a) nitrile(s). Specific examples of the solvent may include, but are not limited to: acetone, butanone, dichloromethane, acetonitrile and acrylonitrile, more preferably dichloromethane. Preferably, the solvent is selected from C₃-C₈Ketone and C₁-C₄One or more of (a) a halogenated alkane.

According to the method of the present invention, in the step (2), the amount of the solvent to be used is not particularly limited and may be conventionally selected. Generally, the weight ratio of solvent to the catalyst a may be from 0.1 to 1000: 1, preferably 0.5 to 200: 1.

according to the process of the invention, step (2), in a preferred embodiment of the invention, the contacting is carried out in the presence of a peroxide compound, the molar ratio of peroxide compound to propylene oxide being from 0.0001 to 0.1: 1. namely propylene oxide, water, CO₂Peroxide, and optionally solvent, are contacted with the catalyst. In the presence of peroxide, propylene oxide, water, CO₂And optionally a solvent, with a catalyst, higher propylene oxide conversion and propylene glycol and propylene carbonate selectivity can be achieved. Preferably, the molar ratio of peroxide to propylene oxide is from 0.001 to 0.05: 1, more preferably 0.001 to 0.01: 1.

according to the method of the present invention, in the step (2), the peroxide is a compound having an-O-bond in its molecular structure, and the general formula is R₇-O-O-R₈(may be hydrogen peroxide and/or an organic peroxide) wherein R₇、R₈Each may be hydrogen or an organic group, preferably R₇、R₈At least one of which is an organic group, e.g., C1-C10 alkyl, or C6-C10 aryl, e.g., t-butyl hydroperoxide, cumene peroxide, cyclohexyl hydroperoxide, peroxyacetic acid, and peroxypropionic acid, with preference given toR₇And R₈Are all organic radicals, more preferably R₇And R₈Both are cumyl groups, i.e. preferably the peroxide is dicumyl peroxide. This further improves propylene oxide conversion and propylene glycol and propylene carbonate selectivity.

When the peroxide is hydrogen peroxide in step (2) according to the method of the present invention, the hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art. From the viewpoint of further improving safety, the process according to the invention preferably uses hydrogen peroxide in the form of an aqueous solution. According to the process of the invention, when the hydrogen peroxide is provided in the form of an aqueous solution, the concentration of the aqueous hydrogen peroxide solution may be a concentration conventional in the art, for example: 20-80 wt%. Aqueous solutions of hydrogen peroxide at concentrations meeting the above requirements may be prepared by conventional methods or may be obtained commercially, for example: can be 30 percent by weight of hydrogen peroxide, 50 percent by weight of hydrogen peroxide or 70 percent by weight of hydrogen peroxide which can be obtained commercially.

According to the process of the present invention, in step (2), the propylene oxide, water and CO₂The ratio of the components can be adjusted according to requirements, and propylene oxide, water and CO are preferred for the invention₂In a molar ratio of 1: 0.1-10:1 to 100, more preferably 1: 0.2-10: 2-50. In the conventional process for producing propylene glycol from propylene oxide, water is used in an excess amount (the molar ratio of propylene oxide to water is generally 1:1 to 100) in order to suppress the formation of by-products. The excessive use of water reduces the reaction efficiency on the one hand, and increases the burden of subsequent separation and purification on the other hand, and also increases the amount of wastewater generated. The method of the invention uses the titanium silicalite molecular sieve containing the template agent as the catalyst, even if the amount of water used is reduced, such as the molar ratio of the propylene oxide to the water is 1:0.1-50, high propylene glycol selectivity can be obtained. Under the condition of considering the selectivity of propylene glycol and propylene carbonate, from the viewpoint of further reducing the amount of water used, the molar ratio of propylene oxide to water is preferably 1:0.1 to 10, more preferably 1: 0.2-5.

According to the method of the present invention, in step (2), the conditions for the contacting may be selected conventionally in the art, for example, the temperature may be 10 to 160 ℃; the pressure may be 0-2.5MPa gauge. The method of the invention can obtain higher propylene oxide conversion rate and propylene glycol and propylene carbonate selectivity even if the contact is carried out under mild conditions. The contact is carried out under mild conditions, so that on one hand, the energy consumption can be reduced, and on the other hand, the reaction is easier to control. According to the method of the present invention, preferably, the contacting conditions include: the temperature can be 20-120 ℃; preferably 0.5 to 2MPa in terms of gauge pressure.

According to the method of the invention, the step (2) can also comprise separating propylene glycol and propylene carbonate from the mixture obtained by the contact. The method for separating propylene glycol and propylene carbonate from the mixture obtained by the contacting is not particularly limited and may be a routine choice in the art. Specifically, the mixture obtained by the contact may be subjected to solid-liquid separation, and the liquid phase obtained by the separation may be subjected to distillation, thereby obtaining propylene glycol and propylene carbonate.

The following examples further illustrate the invention, but do not limit the scope of the invention.

In the following examples and comparative examples, unless otherwise specified, the reactions were carried out in a 250mL general-purpose autoclave using commercially available analytical grade reagents.

In the following examples and comparative examples, the pressures were gauge pressures unless otherwise specified.

In the following examples, the content of the template in the template-containing titanium silicalite molecular sieve was determined by thermogravimetry, and the specific test method was: the weight loss rate of the titanium silicalite molecular sieve at 200-800 ℃ is determined on a thermogravimetric analyzer with the model number TA 951, which is commercially available from DuPont, and corresponds to the content of the template agent, wherein the temperature rise rate is 10 ℃/min, and the test is carried out in a nitrogen atmosphere.

In the following examples and comparative examples, the composition of the liquid phase mixture obtained by the reaction was measured by gas chromatography, and quantified by the normalized normalization method, and the propylene oxide conversion and propylene glycol and propylene carbonate selectivity were calculated by the following formulas.

In the step (2),

(formula IV)

(formula V)

(formula VI)

In the formulas IV, V and VI, X is the conversion rate of the propylene oxide;

is the number of moles of propylene oxide added;

the mole number of the propylene oxide in the liquid phase mixture obtained by the reaction; s_pgIs propylene glycol selective; n is_pgThe mole number of the propylene glycol in the liquid phase mixture obtained by the reaction; s_PCSelectivity for propylene carbonate; n is_PCIs the mole number of the propylene carbonate in the liquid phase mixture obtained by the reaction.

In the step (1), the step (c),

hydrogen peroxide conversion ═ (moles of hydrogen peroxide consumed by the reaction/moles of hydrogen peroxide added) × 100%;

the effective utilization rate of hydrogen peroxide is (the mole number of propylene oxide generated by the reaction/the mole number of hydrogen peroxide consumed by the reaction) × 100%;

propylene oxide selectivity (moles of propylene oxide formed by the reaction/moles of olefin consumed by the reaction) × 100%.

Preparation of example 1

The titanium silicalite TS-1 was prepared as described in Zeolite, 1992, Vol.12, pages 943-950, in the following manner.

At room temperature (20 ℃), 22.5g tetraethyl orthosilicate was mixed with 7.0g tetrapropylammonium hydroxide as a template, 59.8g distilled water was added, and after stirring and mixing, hydrolysis was performed at 60 ℃ for 1.0 hour under normal pressure to obtain a hydrolysis solution of tetraethyl orthosilicate. To the hydrolysis solution was slowly added a solution consisting of 1.1g tetrabutyl titanate and 5.0g anhydrous isopropanol with vigorous stirring, and the resulting mixture was stirred at 75 ℃ for 3h to give a clear and transparent colloid. Placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ for 36h to obtain a mixture of crystallized products. The resulting mixture was filtered, the solid material collected was washed with water, dried at 110 ℃ for 60min, and then calcined at 500 ℃ for 6h to give titanium silicalite a with a titanium oxide content of 2.8 wt.%.

Preparation of example 2

Tetrabutyl titanate is firstly dissolved in an alkali source template tetrapropyl ammonium hydroxide aqueous solution, then silica gel (purchased from Qingdao silica gel factory) is added to obtain a dispersion liquid, and in the dispersion liquid, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: 4: 12: 400, the silicon source is SiO₂The titanium source is calculated as TiO₂The alkali source template is counted as N. The dispersion was sealed with a sealing film in a beaker, and then allowed to stand at room temperature (25 ℃ C., the same applies hereinafter) for 24 hours, followed by stirring at 35 ℃ for 2 hours with magnetic stirring to redisperse the dispersion. Transferring the re-dispersed dispersion liquid into a sealed reaction kettle, carrying out first-stage crystallization for 6h at 140 ℃, then cooling the mixture to 30 ℃, carrying out second-stage retention for 2h, continuing to carry out third-stage crystallization for 12h at 170 ℃ in the sealed reaction kettle (wherein the heating rate from room temperature to the first-stage crystallization temperature is 2 ℃/min, the cooling rate from the first-stage crystallization temperature to the second-stage treatment temperature is 5 ℃/min, and the heating rate from the second-stage treatment temperature to the third-stage crystallization temperature is 10 ℃/min), taking out the obtained crystallized product, directly drying for 2h at 110 ℃, and then roasting for 3h at 550 ℃ to obtain the titanium-silicon molecular sieve B. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained titanium silicalite molecular sieve TS-1 with MFI structure(ii) a Fourier transform infrared spectrogram at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters the molecular sieve framework, and in the titanium silicalite molecular sieve B, the content of titanium oxide is 3.5 wt%, and the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.58 (in the titanium silicalite molecular sieve A prepared in example 1, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 1.05).

Preparation of example 3

Tetrabutyl titanate is firstly dissolved in an alkali source template tetrapropyl ammonium hydroxide aqueous solution, then silica gel (purchased from Qingdao silica gel factory) is added to obtain a dispersion liquid, and in the dispersion liquid, a silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: 2: 10: 600 silicon source of SiO₂The titanium source is calculated as TiO₂The alkali source template is counted as N. The dispersion was sealed with a sealing film in a beaker, and then allowed to stand at 40 ℃ for 10 hours, followed by stirring at 25 ℃ for 0.5 hour with magnetic stirring to redisperse the dispersion. Transferring the re-dispersed dispersion liquid into a sealed reaction kettle, carrying out first-stage crystallization for 8h at 130 ℃, then cooling the mixture to 50 ℃, carrying out second-stage retention for 5h, continuing to carry out third-stage crystallization for 16h at 170 ℃ in the sealed reaction kettle (wherein the heating rate from room temperature to the first-stage crystallization temperature is 1 ℃/min, the cooling rate from the first-stage crystallization temperature to the second-stage treatment temperature is 10 ℃/min, and the heating rate from the second-stage treatment temperature to the third-stage crystallization temperature is 20 ℃/min), taking out the obtained crystallized product, directly drying at 120 ℃ for 3h without filtering and washing steps, and then roasting at 580 ℃ for 2h to obtain the titanium-silicon molecular sieve C. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained titanium silicalite molecular sieve TS-1 with an MFI structure; fourier transform infrared spectrogram at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium silicalite molecular sieve C, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.25, and the content of titanium oxide is 2.6 wt%.

Preparation of example 4

Dissolving tetrabutyl titanate in an alkali source template agent tetrapropyl ammonium hydroxide aqueous solution, and adding silica gel (purchased from Qingdao silica gel factory) to obtain a dispersionA liquid in which a silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: 5: 18: 1000, silicon source is SiO₂The titanium source is calculated as TiO₂The alkali source template is counted as N. Sealing the dispersion liquid in a beaker by using a sealing film, and standing for 8 hours at 45 ℃; transferring the standing dispersion liquid into a sealed reaction kettle, carrying out first-stage crystallization for 6h at 140 ℃, then cooling the mixture to 40 ℃, carrying out second-stage residence for 1h, continuing to carry out third-stage crystallization for 12h at 160 ℃ in the sealed reaction kettle (wherein the heating rate from room temperature to the first-stage crystallization temperature is 5 ℃/min, the cooling rate from the first-stage crystallization temperature to the second-stage treatment temperature is 5 ℃/min, and the heating rate from the second-stage treatment temperature to the third-stage crystallization temperature is 5 ℃/min), taking out the obtained crystallized product, directly drying for 2h at 110 ℃, and then roasting for 3h at 550 ℃ to obtain the titanium-silicon molecular sieve D. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained titanium silicalite molecular sieve TS-1 with an MFI structure; fourier transform infrared spectrogram at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium silicalite molecular sieve D, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.71, and the content of titanium oxide is 4.3 wt%.

Preparation of example 5

The preparation method is as in preparation example 2, except that when preparing the titanium silicalite TS-1, the crystallization temperature in the third stage is also 140 ℃, the titanium silicalite E is obtained, the XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite A prepared in example 1, which indicates that the TS-1 molecular sieve with MFI structure is obtained; in the Fourier transform infrared spectrum at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium silicalite molecular sieve E, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 4.21, and the content of titanium oxide is 3.1 weight percent.

Preparation of example 6

Prepared according to the method of preparation example 2 except that, in the preparation of titanium silicalite TS-1, the crystallization temperature of the first stage is 110 ℃ to obtain titanium silicalite FThe XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained TS-1 molecular sieve with an MFI structure; in the Fourier transform infrared spectrum at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium silicalite molecular sieve F, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.37, and the content of titanium oxide is 3.2 wt%.

Preparation of example 7

The process is as in preparative example 2 except that in the preparation of titanium silicalite TS-1, the crystallization time in the first stage is 12h to obtain titanium silicalite G. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained TS-1 molecular sieve with an MFI structure; in the Fourier transform infrared spectrum at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium silicalite molecular sieve G, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 3.78, and the content of titanium oxide is 3.4 wt%.

Preparation of example 8

The preparation method is as in preparation example 2, except that, when preparing the titanium silicalite TS-1, the second stage is to cool the temperature to 70 ℃ and stay for 2H, so as to obtain the titanium silicalite H. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained TS-1 molecular sieve with an MFI structure; in the Fourier transform infrared spectrum at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium silicalite molecular sieve H, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 2.75, and the content of titanium oxide is 3.1 weight percent.

Preparation of example 9

The process is as in preparative example 2 except that titanium silicalite TS-1 is prepared without a second stage to yield titanium silicalite I. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in example 1, which shows that the obtained TS-1 molecular sieve with an MFI structure; in the Fourier transform infrared spectrum at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve I, the surface silicon-titanium ratio/bulk silicon-titanium ratio is 1.08, and the content of titanium oxide is 2.5 wt%.

Preparation of example 10

The preparation method is as the preparation example 2, except that when the titanium silicalite TS-1 is prepared, the aqueous dispersion is not kept still at room temperature for 12 hours, but is directly fed into a reaction kettle for crystallization to obtain the titanium silicalite J. The XRD crystal phase diagram of the obtained sample is consistent with that of the titanium silicalite molecular sieve A prepared in the step (1) of the example 1, which shows that the obtained titanium silicalite molecular sieve TS-1 with an MFI structure; fourier transform infrared spectrogram at 960cm^-1An absorption peak appears nearby, which indicates that titanium enters a molecular sieve framework, and in the titanium-silicon molecular sieve J, the content of titanium oxide is 3.5 wt%, and the surface silicon-titanium ratio/bulk silicon-titanium ratio is 1.18.

Preparation of example 11

Mixing the titanium silicalite molecular sieve A obtained in preparation example 1 with HNO₃(HNO₃The mass concentration of the titanium dioxide is 10%) and hydrogen peroxide (the mass concentration of the hydrogen peroxide is 7.5%) are mixed, the obtained mixture is stirred and reacted for 5 hours in a closed container at 70 ℃, the temperature of the obtained reaction mixture is reduced to room temperature and then filtered, and the obtained solid-phase substance is dried to constant weight at 120 ℃ to obtain the modified titanium-silicon molecular sieve. Wherein, the titanium silicalite TS-1 is SiO₂The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.1. compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 3.5 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 2.6 percent.

Preparation of example 12

Mixing the titanium silicalite molecular sieve B obtained in preparation example 2 with HNO₃(HNO₃The mass concentration of the titanium dioxide is 10%) and hydrogen peroxide (the mass concentration of the hydrogen peroxide is 7.5%) are mixed, the obtained mixture is stirred and reacted for 5 hours in a closed container at 70 ℃, the temperature of the obtained reaction mixture is reduced to room temperature and then filtered, and the obtained solid-phase substance is dried to constant weight at 120 ℃ to obtain the modified titanium-silicon molecular sieve. Wherein, the titanium silicalite TS-1 is SiO₂The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.1. compared with the titanium silicalite molecular sieve as the raw material, the obtained improvementThe peak area of the absorption peak between 230-310nm in the UV-Vis spectrum of the chiral titanium-silicon molecular sieve is reduced by 3.4 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 2.7 percent.

Preparation of example 13

Mixing the titanium silicalite molecular sieve C prepared in preparation example 3 with a catalyst containing HNO₃(HNO₃The mass concentration of the titanium dioxide is 10%) and hydrogen peroxide (the mass concentration of the hydrogen peroxide is 5%) are mixed, the obtained mixture is stirred and reacted for 4 hours in a closed container at 120 ℃, the temperature of the obtained reaction mixture is reduced to room temperature, then the obtained reaction mixture is filtered, and the obtained solid-phase substance is dried to constant weight at 120 ℃, so that the modified titanium-silicon molecular sieve is obtained. Wherein, the titanium silicalite TS-1 is SiO₂The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 0.4. this sample was similar in its spectral characteristics to the sample of example 1 by X-ray diffraction. Compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 4.1 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 3.6 percent.

Preparation of example 14

Mixing the titanium silicalite molecular sieve D prepared in preparation example 4 with HNO₃(HNO₃15% by mass) and hydrogen peroxide (8% by mass), stirring the obtained mixture in a closed container at 150 ℃ for reaction for 3 hours, cooling the obtained reaction mixture to room temperature, filtering, and drying the obtained solid-phase substance at 120 ℃ to constant weight to obtain the modified titanium-silicon molecular sieve. Wherein, the titanium silicalite TS-1 is SiO₂The molar ratio of the titanium silicalite molecular sieve to the hydrogen peroxide is 1: 2. this sample was similar in its spectral characteristics to the sample of example 1 by X-ray diffraction. Compared with the raw material titanium silicalite molecular sieve, the peak area of the absorption peak between 230 and 310nm in the UV-Vis spectrum of the obtained modified titanium silicalite molecular sieve is reduced by 5.1 percent, and the pore volume determined by a static nitrogen adsorption method is reduced by 4.6 percent.

Propylene oxide preparations 1 to 14

The titanium silicalite molecular sieves prepared in preparation examples 1-14 were used to prepare propylene oxide by the following specific steps:

contacting propylene, methanol and hydrogen peroxide with a titanium silicalite molecular sieve at 40 ℃, under the pressure of 1.5MPa and for 0.5h, wherein the molar ratio of the propylene to the methanol to the hydrogen peroxide is 3:10:1, and the concentration of the titanium silicalite molecular sieve is 0.05 g/mL; and (3) separating out the propylene oxide from the contacted materials by adopting a rectification method, wherein the purity of the propylene oxide is more than 99 percent by weight, and the conversion rate of the hydrogen peroxide, the selectivity of the propylene oxide and the effective utilization rate of the hydrogen peroxide are shown in table 1.

TABLE 1

As can be seen from Table 1, the method for preparing propylene oxide can obtain high hydrogen peroxide conversion rate and propylene oxide selectivity, and simultaneously can obtain high effective utilization rate of hydrogen peroxide, and the catalyst titanium silicalite molecular sieve has long service life.

Examples 1-19 illustrate the process of the present invention.

The raw material propylene oxide used in the following examples and comparative examples was obtained in a purity of 99.5% by the method according to the present invention.

Example 1

(1) Preparation of titanium silicalite TS-1 containing template agent

Prepared as described in Zeolite, 1992, Vol.12, pp 943-950 (omitting the calcination step), in the following manner.

At room temperature (20 ℃), mixing 22.5g tetraethyl orthosilicate with 7.0g tetrapropylammonium hydroxide, adding 59.8g distilled water, stirring and mixing, hydrolyzing at normal pressure and 60 ℃ for 1.0 hour to obtain a hydrolysis solution of tetraethyl orthosilicate, slowly adding a solution consisting of 1.1g tetrabutyl titanate and 5.0g anhydrous isopropanol under vigorous stirring, stirring the obtained mixture at 75 ℃ for 3 hours to obtain a clear transparent colloid, placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ for 3 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water, and dried at 110 ℃ for 60 minutes.

The titanium oxide content of the titanium-silicon molecular sieve containing the template agent is 2.4 weight percent, and the content of the template agent is 14.2 weight percent.

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) feeding the acetone serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring at 35 ℃ for reaction for 1 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 1: 20, the weight ratio of the solvent to the catalyst is 20:1, the weight ratio of the propylene oxide to the catalyst is 20:1, controlling the pressure in the high-pressure reaction kettle to be 2.0 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 2.

Comparative example 1

Propylene glycol and propylene carbonate were prepared in the same manner as in example 1, except that no catalyst was used.

The resulting mixture was filtered, and the composition of the resulting liquid phase mixture was determined by gas chromatography, and the propylene oxide conversion and propylene glycol and propylene carbonate selectivity were calculated, and the results are listed in table 2.

Comparative example 2

Propylene glycol and propylene carbonate were prepared in the same manner as in example 1, except that, in the step (1), the titanium silicalite molecular sieve containing the template was calcined at 500 ℃ for 5 hours to obtain a template-removed titanium silicalite molecular sieve (the content of the template is 0), and the titanium silicalite molecular sieve was used as the catalyst in the step (2).

Example 2

Propylene glycol and propylene carbonate were prepared in the same manner as in example 1, except that, in the step (1), the hollow titanium silicalite HTS containing templating agent was prepared by the following method with reference to the method disclosed in chinese patent CN 1132699C;

taking the TS-1 molecular sieve obtained in the example 1 after roasting the molecular sieve containing the template for 3 hours at 550 ℃, and mixing the molecular sieve with the following components in parts by weight: sulfuric acid (mol): and (3) uniformly mixing water (mol) in a ratio of 100:0.15:150, reacting at 90 ℃ for 5.0 hours, and then filtering, washing and drying according to a conventional method to obtain the acid-treated TS-1 molecular sieve. Mixing the acid treated TS-1 molecular sieve uniformly according to the proportion of molecular sieve (g), triethanolamine (mol), tetrapropylammonium hydroxide (mol) and water (mol) of 100:0.20:0.15:180, placing the mixture into a stainless steel sealed reaction kettle, standing the mixture at a constant temperature of 190 ℃ and autogenous pressure for 0.5 day, cooling and releasing pressure, filtering, washing and drying by a conventional method.

The hollow titanium silicalite molecular sieve containing the template agent has the titanium oxide content of 2.5 weight percent and the template agent content of 6.3 weight percent.

In the step (2), the hollow titanium silicalite molecular sieve HTS containing the template agent is used as a catalyst.

The resulting mixture was filtered, and the composition of the resulting liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and propylene glycol and propylene carbonate selectivity were calculated, and the results are shown in table 2.

Example 3

Propylene glycol and propylene carbonate were prepared in the same manner as in example 1, except that in step (1), the following method was used to prepare a templating agent-containing titanium silicalite Ti-MCM-41, in accordance with the method disclosed in Corma et al, J.Chem.Soc., chem.Commun.,1994,147-148 (omitting the final calcination step).

Adding a mixed solution of amorphous silica Aerosil 200 and 25% tetramethyl ammonium hydroxide aqueous solution into a mixed solution of cetyl trimethyl ammonium bromide and 25% tetramethyl ammonium hydroxide aqueous solution, uniformly mixing, and addingAerosil 200 and tetraethyl titanate were added and the resulting material (molar composition: SiO)₂：TiO₂：SiO₂: cetyl trimethylammonium bromide: tetramethyl ammonium hydroxide: water (60: 1:15.6:10.4:48) is transferred into a stainless steel sealed reaction kettle and is placed for 28 hours at the constant temperature of 140 ℃ to obtain a mixture of crystallized products; the mixture was filtered, washed with water, and dried at 110 ℃ for 60 minutes.

The titanium oxide content of the titanium-silicon molecular sieve containing the template agent is 3 weight percent, and the content of the template agent is 19 weight percent.

In the step (2), a titanium silicalite molecular sieve Ti-MCM-41 containing a template agent is used as a catalyst.

Example 4

Propylene glycol and propylene carbonate were prepared in the same manner as in example 1, except that in step (1), the following procedure was used to prepare a templating agent-containing titanium silicalite Ti-Beta, in accordance with the procedure disclosed in Takashi Tasumi et al, J.chem.Soc., chem.Commun.,1992, 589-Beta.

The preparation process comprises the following steps: tetraethyl titanate and amorphous silica gel Aerosil 200 were added to an aqueous tetraethylammonium hydroxide (TEAOH) solution with stirring at room temperature, followed by the addition of a suitable amount of aluminum nitrate, the molar composition of the gel formed being A1₂O₃:TiO₂:SiO₂:H₂And (3) transferring the formed glue solution into a high-pressure reaction kettle with a polytetrafluoroethylene lining for dynamic crystallization, wherein the crystallization temperature is 130 ℃, the stirring speed is 60rpm, and the crystallization time is 3 days. After cooling, the solid-liquid mixture obtained is subjected to centrifugal separation to obtain a solid and a crystallized mother liquor. And washing the separated solid with water until the pH value is about 9, and drying at 80 ℃ for 5h to obtain the titanium silicalite molecular sieve containing the template agent.

The titanium oxide content of the titanium-silicon molecular sieve containing the template agent is 2.6 weight percent, and the content of the template agent is 16.7 weight percent.

In the step (2), the titanium silicalite Ti-Beta containing the template agent is used as a catalyst.

Example 5

Propylene glycol and propylene carbonate were prepared in the same manner as in example 1, except that in step (2), an equal amount of methylene chloride was used instead of acetone.

Example 6

Propylene glycol and propylene carbonate were produced in the same manner as in example 1, except that in the step (2), propylene oxide, water, carbon dioxide, acetone as a solvent, the titanium silicalite TS-1 produced in the step (1) as a catalyst, and peracetic acid (a 30 wt% aqueous solution of peracetic acid) were fed into a high-pressure reactor, mixed uniformly, and reacted at 35 ℃ for 1 hour with stirring. Wherein the molar ratio of the propylene oxide to the peroxyacetic acid is 0.001: 1.

TABLE 2

Numbering	Propylene oxide conversion (%)	Propylene glycol selectivity (%)	Propylene carbonate selectivity (%)
				Example 1	72.9	69.6	22.7
Comparative example 1	10.9	89.4	0
				Comparative example 2	18.4	91.1	0
Example 2	82.5	72.4	23.9
				Example 3	57.8	61.9	19.4
Example 4	64.5	68.3	22.6
				Example 5	99.9	68.9	22.4
Example 6	88.5	71.2	23.3

Example 7

(1) Preparation of titanium silicalite TS-1 containing template agent

The preparation is described in Zeolite, 1992, Vol.12, pages 943-950, in the following manner.

At room temperature (20 ℃), 22.5 grams of tetraethyl orthosilicate is mixed with 10.0 grams of triethanolamine and 59.8 grams of distilled water is added, after mixing with stirring, the mixture is hydrolyzed at 60 ℃ for 1.0 hour at normal pressure to give a hydrolyzed solution of tetraethyl orthosilicate, a solution consisting of 1.0 gram of tetrabutyl titanate and 5.0 grams of anhydrous isopropanol is slowly added with vigorous stirring, and the resulting mixture is stirred at 75 ℃ for 3 hours to give a clear, transparent colloid. Placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ for 3 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water, and dried at 110 ℃ for 60 minutes to obtain a titanium silicalite molecular sieve containing the templating agent.

The titanium oxide content of the titanium-silicon molecular sieve containing the template agent is 2.1 weight percent, and the content of the template agent is 13.2 weight percent.

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) feeding acetone serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring for reaction at 50 ℃ for 1 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 2: 10, the weight ratio of the solvent to the catalyst is 120: 1, the weight ratio of the propylene oxide to the catalyst is 40: 1, controlling the pressure in the high-pressure reaction kettle to be 1.5 MPa. Then, the obtained mixture is filtered and measured by gas chromatographyThe composition of the resulting liquid phase mixture was calculated and the propylene oxide conversion and propylene glycol and propylene carbonate selectivity were calculated and the results are listed in table 3.

Example 8

(1) Preparation of titanium silicalite TS-1 containing template agent

Mixing 25.5 g of tetraethyl orthosilicate and 15.0 g of n-butylamine at room temperature (20 ℃), adding 40.8 g of distilled water, stirring and mixing, hydrolyzing at normal pressure and 60 ℃ for 1.0 hour to obtain a hydrolysis solution of tetraethyl orthosilicate, slowly adding a solution consisting of 1.0 g of tetrabutyl titanate and 5.0g of anhydrous isopropanol under vigorous stirring, stirring the obtained mixture at 75 ℃ for 3 hours to obtain a clear transparent colloid, placing the colloid in a stainless steel sealed reaction kettle, and standing at the constant temperature of 170 ℃ for 3 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water, and dried at 110 ℃ for 60 minutes to obtain a titanium silicalite molecular sieve containing the templating agent.

The titanium oxide content of the titanium-silicon molecular sieve containing the template agent is 2.0 weight percent, and the content of the template agent is 5.2 weight percent.

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) feeding acetone serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring for reaction at 60 ℃ for 0.5 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 5: 50, the weight ratio of the solvent to the catalyst is 200: 1, the weight ratio of the propylene oxide to the catalyst is 80: 1, controlling the pressure in the high-pressure reaction kettle to be 1.0 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 9

(1) The method is the same as the method of the example 1 to prepare the titanium silicalite TS-1 containing the template agent.

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂Feeding acetonitrile serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring for reaction at 40 ℃ for 1 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 4: 5, the weight ratio of the solvent to the catalyst is 80: 1, the weight ratio of the propylene oxide to the catalyst is 2: 1, controlling the pressure in the high-pressure reaction kettle to be 0.5 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 10

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂Feeding acrylonitrile as a solvent and the titanium silicalite TS-1 prepared in the step (1) as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring at 90 ℃ for reaction for 1 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 3: 2, the weight ratio of the solvent to the catalyst is 180: 1, the weight ratio of the propylene oxide to the catalyst is 5:1, controlling the pressure in the high-pressure reaction kettle to be 1.0 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 11

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂Feeding acetonitrile serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring at 110 ℃ for reaction for 0.5 hour.Wherein propylene oxide, water and CO₂In a molar ratio of 5: 1:1, the weight ratio of the solvent to the catalyst is 10:1, the weight ratio of the propylene oxide to the catalyst is 10:1, controlling the pressure in the high-pressure reaction kettle to be 1.5 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 12

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) feeding the acetone serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring at 70 ℃ for reaction for 1 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 3: 1:15, the weight ratio of solvent to catalyst is 80: 1, the weight ratio of the propylene oxide to the catalyst is 100:1, controlling the pressure in the high-pressure reaction kettle to be 0.5 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 13

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) delivering butanone serving as a solvent and the titanium silicalite TS-1 prepared in the step (1) serving as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring for reaction at 30 ℃ for 2 hours. Wherein propylene oxide, water and CO₂In a molar ratio of 2: 1: 80, the weight ratio of the solvent to the catalyst is 40: 1, the weight ratio of the propylene oxide to the catalyst is 60:1, controlling the pressure in the high-pressure reaction kettle to be 1.5 MPa. Then, the obtained mixture was filtered, and the obtained liquid phase mixture was measured by gas chromatographyAnd propylene oxide conversion and propylene glycol and propylene carbonate selectivity were calculated, the results are listed in table 3.

Example 14

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) feeding the titanium silicalite TS-1 prepared in the step (1) as a catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring at 60 ℃ for reaction for 1 hour. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 10: 5, the weight ratio of the propylene oxide to the catalyst is 1:1, controlling the pressure in the high-pressure reaction kettle to be 1.0 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 15

(1) The method is the same as the method of the example 7 to prepare the titanium silicalite TS-1 containing the template agent.

(2) Preparation of propylene glycol and propylene carbonate

Mixing propylene oxide, water and CO₂And (2) feeding the solvent acetone and the titanium silicalite TS-1 prepared in the step (1) as the catalyst into a high-pressure reaction kettle, uniformly mixing, and stirring at 60 ℃ for reaction for 3 hours. Wherein propylene oxide, water and CO₂In a molar ratio of 1: 4: 25, the weight ratio of solvent to catalyst is 50: 1, the weight ratio of the propylene oxide to the catalyst is 20:1, controlling the pressure in the high-pressure reaction kettle to be 0.6 MPa. Then, the obtained mixture was filtered, and the composition of the obtained liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and the propylene glycol and propylene carbonate selectivities were calculated, and the results are shown in table 3.

Example 16

Propylene glycol and propylene carbonate were produced in the same manner as in example 15, except that in the step (2), propylene oxide, water, CO₂Titanium produced in step (1) as a catalystFeeding the silicon molecular sieve TS-1 and hydrogen peroxide (with the concentration of 30 weight percent) into a high-pressure reaction kettle, uniformly mixing, and stirring and reacting at 60 ℃ for 3 hours. Wherein the molar ratio of the propylene oxide to the hydrogen peroxide is 0.01: 1.

the resulting mixture was filtered, and the composition of the resulting liquid phase mixture was measured by gas chromatography, and the propylene oxide conversion and propylene glycol and propylene carbonate selectivity were calculated, and the results are shown in table 3.

Example 17

Propylene glycol and propylene carbonate were produced in the same manner as in example 16, except that in the step (2), dicumyl peroxide was used in place of hydrogen peroxide, and the other conditions were the same.

Example 18

Propylene glycol and propylene carbonate were prepared according to the method of example 15, except that the catalyst used in step (2) was prepared as follows:

at room temperature (20 ℃), mixing 22.5g tetraethyl orthosilicate with 7.0g tetrapropylammonium hydroxide, adding 59.8g distilled water, stirring and mixing, hydrolyzing at normal pressure and 60 ℃ for 1.0 hour to obtain a hydrolysis solution of tetraethyl orthosilicate, slowly adding a solution consisting of 1.1g tetrabutyl titanate and 5.0g anhydrous isopropanol under vigorous stirring, stirring the obtained mixture at 75 ℃ for 3 hours to obtain a clear transparent colloid, placing the colloid in a stainless steel sealed reaction kettle, and standing at a constant temperature of 170 ℃ for 3 days to obtain a mixture of crystallized products; the mixture was filtered, washed with water, dried at 110 ℃ for 60 minutes and calcined at 360 ℃ for 3h under an air atmosphere.

The titanium oxide content of the prepared titanium silicalite molecular sieve containing the template agent is 2.5 weight percent, and the content of the template agent is 0.8 weight percent. The other conditions were the same.

Example 19

Propylene glycol and propylene carbonate were produced in the same manner as in example 15, except that, in step (2), the temperature was 200 ℃ and the results are shown in Table 3.

Comparative example 3

Propylene glycol and propylene carbonate were produced in the same manner as in the step (2) of example 15, except that in the step (1), the titanium silicalite molecular sieve containing the template was calcined at 500 ℃ for 5 hours to obtain a titanium silicalite molecular sieve (the content of the template was 0), and the titanium silicalite molecular sieve was used as the catalyst in the step (2).

Comparative example 4

Propylene glycol and propylene carbonate were prepared in the same manner as in comparative example 3, except that triethanolamine, the templating agent, in the same amount as in the titanium silicalite molecular sieve of example 15, was added simultaneously during the contacting.

TABLE 3

Numbering	Propylene oxide conversion (%)	Propylene glycol selectivity(％)	Propylene carbonate selectivity (%)
				Example 7	55.6	83.1	14.3
Example 8	63.2	66.5	29.1
				Example 9	44.7	93.4	5.3
Example 10	53.1	75.3	20.5
				Example 11	13.8	59.4	27.9
Example 12	24.4	61.1	32.6
				Example 13	19.1	85.8	13.5
Example 14	91.6	88.2	11.4
				Example 15	83.6	83.8	10.2
Example 16	88.2	85.4	12.6
				Example 17	93.4	86.3	13.2
Example 18	67.8	77.6	5.9
				Example 19	98.9	76.2	8.7
Comparative example 3	24.4	86.2	0
				Comparative example 4	68.2	55.3	10.8

The results of tables 2 and 3 demonstrate that the process of the present invention uses a templating agent-containing titanium silicalite as a catalyst prepared from propylene oxide, water and CO₂The catalyst for preparing propylene glycol and propylene carbonate can obtain high propylene oxide conversion rate and propylene glycol and propylene carbonate selectivity.

The preferred embodiments of the present invention have been described in detail, however, the present invention is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solution of the present invention within the technical idea of the present invention, and these simple modifications are within the protective scope of the present invention.

Claims

1. A method for simultaneously preparing propylene glycol and propylene carbonate is characterized by comprising the following steps:

(1) under the condition of epoxidation, propylene is oxidized to prepare propylene oxide;

(2) the propylene oxide, water and CO obtained in the step (1) are mixed₂Contacting with a catalyst A, wherein the catalyst A comprises a titanium silicalite molecular sieve containing a template agent;

in the step (1), propylene is contacted with hydrogen peroxide and a catalyst B, the catalyst B contains a titanium silicalite molecular sieve, at least part of the titanium silicalite molecular sieve TS-1 is a titanium silicalite molecular sieve TS-1, and the titanium silicalite molecular sieve TS-1 is prepared by a method comprising the following steps:

(A) dispersing an inorganic silicon source in an aqueous solution containing a titanium source and an alkali source template agent, and optionally supplementing water to obtain a dispersion liquid, wherein the ratio of the silicon source: a titanium source: alkali source template agent: the molar ratio of water is 100: (0.5-8): (5-30): (100-2000), the inorganic silicon source is SiO₂The titanium source is calculated as TiO₂The alkali source template is counted as OH^-Or N is counted;

(B) optionally, standing the dispersion at 15-60 ℃ for 6-24 hours;

(C) and (3) sequentially carrying out stage (1), stage (2) and stage (3) crystallization on the dispersion liquid obtained in the step (A) or the dispersion liquid obtained in the step (B) in a sealed reaction kettle, wherein the stage (1) is crystallized for 6-72 hours at the temperature of 80-150 ℃, the stage (2) is cooled to the temperature of not higher than 70 ℃ and the retention time is at least 0.5 hour, the stage (3) is heated to the temperature of 120-phase and 200 ℃, and then the crystallization is carried out for 6-96 hours.

2. The process according to claim 1, wherein in the step (1), the propylene oxide is prepared by oxidizing propylene as follows:

in the presence of a solvent, propylene is contacted with hydrogen peroxide and a catalyst B, wherein the catalyst B contains a titanium silicalite molecular sieve, and propylene oxide is obtained by separation.

3. The process of claim 1, wherein in step (1), the epoxidation conditions comprise: the solvent is methanol, and the mol ratio of the propylene to the methanol to the hydrogen peroxide is (1-5) to (5-20) to 1; the contact temperature is 20-60 ℃, the contact pressure is 0.1-1.5MPa, and the contact time is 0.2-1 h.

4. The method according to any one of claims 1 to 3, wherein in the catalyst B, at least part of the titanium silicalite is a modified titanium silicalite, and the modified titanium silicalite is a titanium silicalite subjected to a modification treatment, wherein the modification treatment comprises contacting the titanium silicalite as a raw material with a modification liquid containing nitric acid and at least one peroxide.

5. The method of claim 4, wherein the molar ratio of the titanium silicalite molecular sieve to the peroxide as the raw material in the modification treatment is 1: (0.01-5), the molar ratio of the peroxide to the nitric acid is 1: (0.01-50), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.

6. The method of claim 4, wherein the molar ratio of the titanium silicalite molecular sieve to the peroxide as the raw material in the modification treatment is 1: (0.05-3), and the molar ratio of the peroxide to the nitric acid is 1: (0.1-20), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.

7. The method of claim 4, wherein the molar ratio of the titanium silicalite molecular sieve to the peroxide as the raw material in the modification treatment is 1: (0.1-2), the molar ratio of the peroxide to the nitric acid is 1: (0.2-10), wherein the titanium silicalite molecular sieve is calculated by silicon dioxide.

8. The method of claim 4, wherein, in the modification treatment, the molar ratio of the peroxide to the nitric acid is 1: (0.5-5).

9. The method of claim 4, wherein, in the modification treatment, the molar ratio of the peroxide to the nitric acid is 1: (0.6-3.5).

10. The method according to claim 4, wherein the concentrations of the peroxide and the nitric acid in the modification liquid are each 0.1 to 50% by weight.

11. The method according to claim 4, wherein the concentrations of the peroxide and the nitric acid in the modification liquid are each 0.5 to 25% by weight.

12. The method according to claim 4, wherein the concentrations of the peroxide and the nitric acid in the modification liquid are each 5 to 15% by weight.

13. The method of claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as a raw material is contacted with the modification solution at a temperature of 10-350 ℃, the contact is carried out in a container with a pressure of 0-5MPa, the pressure is gauge pressure, and the contact duration is 1-10 hours.

14. The method of claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as a raw material is contacted with the modification solution at a temperature of 20-300 ℃.

15. The method of claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as a raw material is contacted with the modification solution at a temperature of 50-250 ℃.

16. The method of claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as a raw material is contacted with the modification solution at a temperature of 60-200 ℃.

17. The method of claim 4, wherein the duration of the contacting in the modification treatment is 3-5 hours.

18. The process according to claim 4, wherein the peroxide is selected from hydrogen peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, ethylbenzene hydroperoxide, cyclohexyl hydroperoxide, peroxyacetic acid and peroxypropionic acid.

19. The method as claimed in claim 4, wherein, in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by more than 2% in the ultraviolet-visible spectrum based on the titanium silicalite molecular sieve as the raw material; the pore volume of the modified titanium-silicon molecular sieve is reduced by more than 1 percent, and the pore volume is determined by adopting a static nitrogen adsorption method.

20. The method as claimed in claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification solution to such an extent that, based on the titanium silicalite molecular sieve as the raw material, in the ultraviolet-visible spectrum, the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 2-30%, and the pore volume of the modified titanium silicalite molecular sieve is reduced by 1-20%, wherein the pore volume is determined by a static nitrogen adsorption method.

21. The method as claimed in claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification solution to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 2.5-15% and the pore volume of the modified titanium silicalite molecular sieve is reduced by 1.5-10% in the UV-visible spectrum based on the titanium silicalite molecular sieve as the raw material, wherein the pore volume is determined by a static nitrogen adsorption method.

22. The method as claimed in claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification solution to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 3-10% and the pore volume of the modified titanium silicalite molecular sieve is reduced by 2-5% in the ultraviolet-visible spectrum based on the titanium silicalite molecular sieve as the raw material, and the pore volume is determined by a static nitrogen adsorption method.

23. The method as claimed in claim 4, wherein in the modification treatment, the titanium silicalite molecular sieve as the raw material is contacted with the modification liquid to such an extent that the peak area of the absorption peak of the modified titanium silicalite molecular sieve between 230-310nm is reduced by 3-6% in the UV-visible spectrum based on the titanium silicalite molecular sieve as the raw material.

24. The method of claim 1, wherein in the catalyst B, at least a part of the titanium silicalite molecular sieves is titanium silicalite molecular sieves TS-1, and the surface silicon-titanium ratio of the titanium silicalite molecular sieves TS-1 is not lower than the bulk silicon-titanium ratio, wherein the silicon-titanium ratio is the molar ratio of silicon oxide to titanium oxide, the surface silicon-titanium ratio is determined by X-ray photoelectron spectroscopy, and the bulk silicon-titanium ratio is determined by X-ray fluorescence spectroscopy.

25. A method as claimed in claim 24 wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2 or greater.

26. The method of claim 24, wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.2-5.

27. The method of claim 24, wherein the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.5-4.5.

28. The process as claimed in claim 1, wherein the crystallization in stage (1) is carried out at 110-140 ℃ for 6-72 hours.

29. The process as claimed in claim 1, wherein the crystallization in stage (1) is carried out at 120-140 ℃ for 6-72 hours.

30. The process as claimed in claim 1, wherein the crystallization in stage (1) is carried out at 130-140 ℃ for 6-72 hours.

31. The process according to claim 1, wherein the stage (1) is crystallized at 80-150 ℃ for 6-8 hours.

32. The process as claimed in claim 1, wherein the stage (1) is crystallized at 110-140 ℃ for 6-8 hours.

33. The process as claimed in claim 1, wherein the stage (1) is crystallized at 120-140 ℃ for 6-8 hours.

34. The process as claimed in claim 1, wherein the crystallization in stage (1) is carried out at 130-140 ℃ for 6-8 hours.

35. The process according to claim 1, wherein the temperature of stage (2) is reduced to not more than 70 ℃ and the residence time is at least 1-5 hours.

36. The process as claimed in claim 1, wherein the temperature in stage (3) is raised to 140 ℃ and 180 ℃ and the recrystallization is carried out for 6 to 96 hours.

37. The method as claimed in claim 1, wherein the temperature in the stage (3) is raised to 160-170 ℃ and the recrystallization is carried out for 6-96 hours.

38. The method as claimed in claim 1, wherein the temperature in the stage (3) is raised to 200 ℃ and then the crystallization is carried out for 12-20 hours.

39. The method as claimed in claim 1, wherein the temperature in the stage (3) is raised to 140 ℃ and 180 ℃ for recrystallization for 12-20 hours.

40. The method as claimed in claim 1, wherein the temperature in the stage (3) is raised to 160-170 ℃ and the recrystallization is carried out for 12-20 hours.

41. The method of claim 1, wherein stage (1) and stage (3) satisfy one or both of the following conditions:

condition 1: the crystallization temperature of the stage (1) is lower than that of the stage (3);

condition 2: the crystallization time of stage (1) is less than the crystallization time of stage (3);

wherein the temperature of the stage (2) is reduced to not higher than 50 ℃ and the retention time is at least 1 hour.

42. The method of claim 1, wherein stage (1) and stage (3) satisfy one or both of the following conditions:

condition 1: the crystallization temperature of the stage (1) is 10-50 ℃ lower than that of the stage (3);

condition 2: the crystallization time of stage (1) is 5-24 hours shorter than that of stage (3).

43. The method of claim 1, wherein stage (1) and stage (3) satisfy one or both of the following conditions:

condition 1: the crystallization temperature of the stage (1) is 20-40 ℃ lower than that of the stage (3);

condition 2: the crystallization time of stage (1) is 6-12 hours shorter than that of stage (3).

44. The method of claim 1, wherein,

the titanium source is inorganic titanium salt and/or organic titanate;

the alkali source template agent is one or more than two of quaternary ammonium hydroxide, aliphatic amine and aliphatic alcohol amine;

the inorganic silicon source is silica gel and/or silica sol;

the organic titanate is selected from the general formula R⁷ ₄TiO₄A compound of formula (I), R⁷Selected from alkyl groups having 2 to 4 carbon atoms.

45. The method of claim 1, wherein the alkali-source templating agent is a quaternary ammonium base.

46. The method of claim 1, wherein the alkali-source templating agent is tetrapropylammonium hydroxide.

47. The method of claim 44, wherein the inorganic titanium salt is TiCl₄、Ti(SO₄)₂And TiOCl₂One or more than two of them.

48. The method of claim 1, wherein in the catalyst A, the content of the template in the template-containing titanium silicalite molecular sieve is 0.1-25 wt%; the content of the titanium silicalite molecular sieve containing the template agent in the catalyst is more than 50 weight percent.

49. The process of claim 1 or 48, wherein in catalyst A, the templating agent is one or more of a quaternary ammonium base, an aliphatic amine, and an aliphatic alcohol amine.

50. The process of claim 1 or 48, wherein in step (2), the contacting is carried out in the presence of a peroxide in a molar ratio of peroxide to propylene oxide of (0.0001-0.1): 1, the peroxide is dicumyl peroxide.

51. The process of claim 1 or 48, wherein in step (2), the contacting is carried out in the presence of a solvent in a weight ratio of solvent to catalyst A of from 0.1 to 1000: 1, the solvent is selected from C₃-C₈Ketone (b), C₁-C₄And C₂-C₈One or more of (A) nitrile(s), propylene oxide, water and CO₂In a molar ratio of 1: (0.1-10): (1-100); the contacting is carried out at a temperature of 10-160 ℃; the weight ratio of propylene oxide to the catalyst A is (0.1-100): 1; the contacting is carried out at a pressure of 0 to 2.5MPa in gauge pressure.