Process for the oxidation of propylene

Abstract

The present disclosure relates to a propylene oxidation method, which comprises the following steps: S1, carrying out a first reaction of propylene, an oxidant and methanol in the presence of a first catalyst to obtain a first reaction mixture, the first catalyst containing a titanium-silicon molecular sieve; S2, mixing the first reaction mixture with a second catalyst to carry out a second reaction, the second catalyst containing a titanium-silicon-aluminum molecular sieve; the molar ratio of propylene, the oxidant and methanol is 1:(0.1-10):(10.5-100); the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1:(0.1-50). The method can produce propylene glycol monomethyl ether under mild conditions.

Description

Technical Field

[0001] This disclosure relates to a method for propylene oxidation. Background Technology

[0002] Propylene glycol monomethyl ether, also known as propylene glycol methyl ether, comprises two isomers: 1-methoxy-2-propanol (MME-1) and 2-methoxy-1-propanol (MME-2). Propylene glycol methyl ether has a faint ether odor but no strong, pungent smell, making its applications more widespread and safer. It is used in styrene-acrylic emulsions, acrylic emulsions, and latex paint systems, where it lowers film-forming temperature, promotes film coagulation, and ensures a good coating condition. Besides being used as a solvent in various high-grade coatings, it is also used in printing inks to control evaporation rates and as a viscosity modifier. It can also be used as a chemical intermediate, as a viscosity modifier in brake fluid formulations, and, because propylene glycol methyl ether is miscible with water in any proportion, as a solvent in metal cleaning agent formulations or in automotive anti-icing fluids to lower the freezing point, among many other applications. It can also be used as a raw material in organic synthesis. Propylene glycol ethers, like ethylene glycol ethers, belong to the class of diol ether solvents. Propylene glycol ethers are less toxic to humans than ethylene glycol ethers and are classified as low-toxicity ethers. Due to the presence of both ether and hydroxyl groups in their molecular structure, they exhibit excellent solubility, suitable volatility, and reactivity, leading to their wide range of applications. Currently, propylene glycol ethers are primarily produced by combining propylene with alcohols. However, most propylene production worldwide currently utilizes the chlorohydrin process and co-oxidation process. The former causes severe corrosion and pollution, while the latter requires significant investment and produces large amounts of byproducts, thus limiting the production of propylene glycol ethers from the perspective of raw materials.

[0003] Therefore, it is of great practical significance to develop a new, environmentally friendly and simple process for preparing propylene glycol monomethyl ether from propylene, which addresses the shortcomings of existing processes. Summary of the Invention

[0004] The purpose of this disclosure is to provide a propylene oxidation method that can produce propylene glycol monomethyl ether, particularly 2-methoxy-1-propanol (MME-2), under mild conditions.

[0005] To achieve the above objectives, this disclosure provides a method for propylene oxidation, the method comprising the following steps:

[0006] S1. Propylene, oxidant and methanol are subjected to a first reaction in the presence of a first catalyst to obtain a first reaction mixture, wherein the first catalyst contains titanium silicate molecular sieve.

[0007] S2. The first reaction mixture is mixed with the second catalyst to carry out the second reaction, wherein the second catalyst contains titanium silicon aluminum molecular sieve;

[0008] The molar ratio of propylene, oxidant and methanol is 1:(0.1-5):(10.5-100); the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1:(0.1-50).

[0009] Optionally, the molar ratio of propylene, oxidant and methanol is 1:(0.2-5):(15-80); the weight ratio of propylene, first catalyst and second catalyst is 100:(2-1000):(5-200), preferably 100:(5-500):(10-100);

[0010] The oxidant is selected from hydrogen peroxide, tert-butyl hydroperoxide, cumene peroxide, cyclohexyl hydroperoxide, peracetic acid, or peroxypropionic acid.

[0011] Optionally, the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1:(0.2-5);

[0012] The conditions for the first reaction are: temperature 0-80℃, pressure 0.1-2.5MPa;

[0013] The conditions for the second reaction are: temperature 0-80℃ and pressure 0.1-2.5MPa.

[0014] Optionally, the titanium-silicon molecular sieve is an MFI type titanium-silicon molecular sieve, a MEL type titanium-silicon molecular sieve, a MWW type titanium-silicon molecular sieve, a hexagonal titanium-silicon molecular sieve, or an MRE type titanium-silicon molecular sieve.

[0015] The titanium-silicon-aluminum molecular sieve is an MFI structure titanium-silicon-aluminum molecular sieve, a MEL structure titanium-silicon-aluminum molecular sieve, a BEA structure titanium-silicon-aluminum molecular sieve, a MWW structure titanium-silicon-aluminum molecular sieve, a MOR structure titanium-silicon-aluminum molecular sieve, a TUN structure titanium-silicon-aluminum molecular sieve, or a two-dimensional hexagonal structure titanium-silicon-aluminum molecular sieve.

[0016] Optionally, the preparation steps of the titanium-silicon-aluminum molecular sieve include:

[0017] (1) The first discharge agent is mixed with an organic acid solution and slurryed, and the resulting slurry is subjected to a first heat treatment to separate the first solid. The first discharge agent is the discharge agent of the reaction device with titanium silicon molecular sieve as the catalyst active component. The conditions of the first heat treatment are: temperature 20-45℃ and time 1-30h.

[0018] (2) The first solid, silicon source, aluminum source, titanium source and alkali source are mixed in the presence of an aqueous solvent and then subjected to a second heat treatment. The conditions for the second heat treatment are: temperature of 100-200℃ and time of 0.5-25h.

[0019] Alternatively, the preparation steps of the titanium-silicon-aluminum molecular sieve include:

[0020] a. The second discharge agent is mixed with an organic acid solution and slurryed, and the resulting slurry is subjected to a third heat treatment to separate the second solid. The second discharge agent is the discharge agent of the reaction device with silica-alumina molecular sieve as the catalyst active component. The conditions of the third heat treatment are: temperature 50-150℃, time 0.5-40h.

[0021] b. The second solid, silicon source, titanium source and alkali source are mixed in the presence of an aqueous solvent and then subjected to a fourth heat treatment. The conditions for the fourth heat treatment are: temperature of 100-200℃ and time of 0.5-25h.

[0022] Optionally, the weight ratio of the first discharge agent, titanium source, aluminum source, organic acid, alkali source, and water is 100:(0.1-10):(0.1-10):(0.005-50):(0.5-50):(20-1000), where the first discharge agent is calculated as SiO2, and the organic acid is calculated as H2O. + When the alkali source contains nitrogen, it is calculated as N; when the alkali source does not contain nitrogen, it is calculated as OH. - The molar ratio of the silicon source (calculated as SiO2) to the titanium source (calculated as TiO2) is (5-20):1; the concentration of the organic acid solution is greater than 0.1 mol / L.

[0023] Optionally, the discharge agent of the reaction device using titanium silicate molecular sieve as the catalyst active component in step (1) is at least one selected from the discharge agent of the ammonium oximation reaction device, the discharge agent of the hydroxylation reaction device, and the discharge agent of the epoxidation reaction device;

[0024] Preferably, the titanium-silicon molecular sieve in step (1) is an MFI structure titanium-silicon molecular sieve, and the activity of the first discharge agent is less than 50% of the activity of the titanium-silicon molecular sieve when it is fresh.

[0025] Preferably, in step (2), the aluminum source and the alkali source are first mixed in the presence of an aqueous solvent to obtain a mixed solution, and then the mixed solution is mixed with the first solid and the titanium source before the second heat treatment is performed.

[0026] Optionally, the weight ratio of the second discharge agent, titanium source, organic acid, alkali source, and water is 100:(0.1-10):(0.005-50):(0.5-50):(20-1000), where the second discharge agent is calculated as SiO2, and the organic acid is calculated as H2O. + When the alkali source contains nitrogen, it is calculated as N; when the alkali source does not contain nitrogen, it is calculated as OH. -The molar ratio of the silicon source (calculated as SiO2) to the titanium source (calculated as TiO2) is (5-20):1; the concentration of the organic acid solution is greater than 0.1 mol / L.

[0027] Optionally, the discharge agent of the reaction device using silica-alumina molecular sieve as the catalyst active component in step a is the discharge agent of the synthesis reaction device of hydrogen sulfide and methanol;

[0028] Preferably, the silica-alumina molecular sieve in step a is an MFI-structured silica-alumina molecular sieve, and the activity of the second discharge agent is less than 50% of the activity of the silica-alumina molecular sieve when it is fresh.

[0029] Optionally, the organic acid is a naphthenic acid, peracetic acid, or perpropionic acid; the base source is ammonia, aliphatic amine, aliphatic alcohol amine, or quaternary ammonium base; the aluminum source is aluminum sol, aluminum salt, aluminum hydroxide, or aluminum oxide; the titanium source is inorganic titanium salt and / or organic titanate; and the silicon source is organic silicate ester.

[0030] Through the above technical solutions, the method disclosed herein effectively reduces the reaction temperature and significantly improves the propylene conversion rate during propylene oxidation by using different catalysts sequentially. Furthermore, by adjusting the amount of methanol, the selectivity of 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether can be improved. In addition, the catalyst in this method is easily recyclable, the entire process is environmentally friendly, simple and easy to control, and requires no special equipment, making it suitable for industrial production and application.

[0031] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Detailed Implementation

[0032] The following provides a detailed description of specific embodiments of this disclosure. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit this disclosure.

[0033] This disclosure provides a method for propylene oxidation, the method comprising the following steps:

[0034] S1. Propylene, oxidant and methanol are subjected to a first reaction in the presence of a first catalyst to obtain a first reaction mixture, wherein the first catalyst contains titanium silicate molecular sieve.

[0035] S2. The first reaction mixture is mixed with the second catalyst to carry out the second reaction, wherein the second catalyst contains titanium silicon aluminum molecular sieve;

[0036] The molar ratio of propylene, oxidant and methanol is 1:(0.1-5):(10.5-100); the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1:(0.1-50).

[0037] During their research, the inventors of this invention unexpectedly discovered that in the propylene oxidation process, by using different catalysts sequentially, especially by introducing a catalyst containing titanium silicate alumina molecular sieves later, the reaction temperature can be effectively reduced and the conversion rate of propylene can be significantly improved. At the same time, by adjusting the amount of methanol, the selectivity of propylene glycol monomethyl ether, especially the selectivity of 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether, can also be improved.

[0038] To achieve the desired reaction effect, the molar ratio of propylene, oxidant and methanol is preferably 1:(0.2-5):(15-80). The ratio of the reaction time of the first reaction to the reaction time of the second reaction is preferably 1:(0.1-10), more preferably 1:(0.2-5).

[0039] According to the method of this disclosure, the oxidant may be selected from hydrogen peroxide, tert-butyl hydroperoxide, cumene peroxide, cyclohexyl hydroperoxide, peracetic acid, or perpropionic acid. The oxidant is preferably provided in the form of an aqueous solution.

[0040] According to this disclosure, the amounts of the first catalyst and the second catalyst are determined to achieve the catalytic function. For example, the weight ratio of propylene, the first catalyst and the second catalyst can be 100:(2-1000):(5-200), preferably 100:(5-500):(10-100).

[0041] In the method disclosed herein, propylene oxidation can be carried out under relatively mild conditions. The conditions for the first reaction can be: a temperature of 0-80°C, preferably 30-60°C; and a pressure of 0.1-2.5 MPa, preferably 1-1.5 MPa. The conditions for the second reaction can be: a temperature of 0-80°C, preferably 30-60°C; and a pressure of 0.1-2.5 MPa, preferably 1-1.5 MPa.

[0042] According to this disclosure, the titanium-silicon molecular sieve can be an MFI type titanium-silicon molecular sieve, a MEL type titanium-silicon molecular sieve, a MWW type titanium-silicon molecular sieve, a hexagonal titanium-silicon molecular sieve, or an MRE type titanium-silicon molecular sieve, and is more preferably a TS-1 molecular sieve, a TS-2 molecular sieve, a Ti-MCM-22 molecular sieve, a Ti-MCM-41 molecular sieve, a Ti-SBA-15 molecular sieve, or a Ti-ZSM-48 molecular sieve. The titanium-silicon molecular sieve can be prepared using existing technologies or is commercially available.

[0043] According to this disclosure, the titanium-silicon-aluminum molecular sieve refers to a general term for a class of zeolites in which titanium and aluminum atoms replace a portion of the silicon atoms in the crystal lattice framework. When the catalyst contains a titanium-silicon-aluminum molecular sieve, the titanium-silicon-aluminum molecular sieve can be a common titanium-silicon-aluminum molecular sieve with various topologies, for example: the titanium-silicon-aluminum molecular sieve can be an MFI-structured titanium-silicon-aluminum molecular sieve, a MEL-structured titanium-silicon-aluminum molecular sieve (such as TS-2), a BEA-structured titanium-silicon-aluminum molecular sieve, a MWW-structured titanium-silicon-aluminum molecular sieve, a MOR-structured titanium-silicon-aluminum molecular sieve, a TUN-structured titanium-silicon-aluminum molecular sieve, or a two-dimensional hexagonal titanium-silicon-aluminum molecular sieve. The titanium-silicon-aluminum molecular sieve is preferably an MFI-structured titanium-silicon-aluminum molecular sieve, a MEL-structured titanium-silicon-aluminum molecular sieve, or a BEA-structured titanium-silicon-aluminum molecular sieve, and more preferably an MFI-structured titanium-silicon-aluminum molecular sieve.

[0044] According to this disclosure, the purpose of this disclosure can be achieved by using a titanium silicate aluminate molecular sieve as a catalyst in step S2. However, the inventors of this disclosure have found in their research that titanium silicate aluminate molecular sieves prepared by a specific method are particularly advantageous for improving the selectivity of 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether.

[0045] Therefore, according to a preferred embodiment of this disclosure, the preparation steps of the titanium-silicon-aluminum molecular sieve include:

[0046] (1) The first discharge agent is mixed with an organic acid solution and slurryed, and the resulting slurry is subjected to a first heat treatment to separate the first solid. The first discharge agent is the discharge agent of the reaction device with titanium silicon molecular sieve as the catalyst active component. The conditions of the first heat treatment are: temperature of 20-45℃, time of 1-30h, preferably 1-24h, more preferably 10-20h.

[0047] (2) The first solid, silicon source, aluminum source, titanium source and alkali source are mixed in the presence of an aqueous solvent and then subjected to a second heat treatment. The conditions for the second heat treatment are: temperature of 100-200℃, preferably 120-180℃, more preferably 140-170℃, and time of 0.5-25h, preferably 2-24h, more preferably 5-20h.

[0048] In the preferred embodiment described above, the relative crystallinity of the first solid obtained after the first heat treatment can be 70-90%. Under specific first heat treatment conditions, the first discharge agent can be processed into a first solid with a specific relative crystallinity, and then subjected to a second heat treatment to obtain a titanium-silicon-aluminum molecular sieve with excellent catalytic performance. This sieve can further improve the selectivity of 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether in the reaction of this disclosure. The relative crystallinity of the solid refers to the crystallinity of the solid relative to the fresh agent corresponding to the discharge agent.

[0049] In the preferred embodiment described above, the discharge agent of the reaction device using titanium-silicon molecular sieve as the catalyst active component can be a discharge agent discharged from various devices using titanium-silicon molecular sieve as the catalyst active component, for example, a discharge agent discharged from an oxidation reaction device using titanium-silicon molecular sieve as the catalyst active component. The oxidation reaction can be various oxidation reactions. For example, the discharge agent of the reaction device using titanium-silicon molecular sieve as the catalyst active component can be at least one of the discharge agents of ammonium oxime reaction devices, hydroxylation reaction devices, and epoxidation reaction devices. Specifically, it can be at least one of the discharge agents of cyclohexanone ammonium oxime reaction devices, phenol hydroxylation reaction devices, and propylene epoxidation reaction devices. Preferably, the discharge agent is a catalyst deactivated under alkaline conditions. Therefore, for the present invention, the first discharge agent is preferably the discharge agent of cyclohexanone ammonium oxime reaction devices (such as deactivated titanium-silicon molecular sieve TS-1, powder, with a particle size of 100-500 nm).

[0050] The discharge agent refers to a deactivated catalyst whose activity cannot be restored to 50% of its initial activity using conventional regeneration methods such as solvent washing or calcination (initial activity refers to the average activity of the catalyst within 1 hour under the same reaction conditions. For example, in actual cyclohexanone oxime reactions, the initial activity of the catalyst generally needs to reach above 95%). The activity of the discharge agent varies depending on its source. Generally, the activity of the discharge agent can be 5-95% of the activity of the titanium-silicon molecular sieve when it is fresh (i.e., the activity of the fresh agent). Preferably, the activity of the first discharge agent can be less than 50% of the activity of the titanium-silicon molecular sieve when it is fresh, and more preferably, the activity of the first discharge agent can be 10-40% of the activity of the titanium-silicon molecular sieve when it is fresh. The activity of the titanium-silicon molecular sieve when it is fresh is generally above 90%, and usually above 95%.

[0051] The discharge agent can be derived from industrial deactivating agents or deactivated catalysts after reaction in the laboratory. Of course, from the perspective of preparation effect, the method of this disclosure can also use fresh molecular sieves such as titanium-silicon molecular sieves as raw materials, but it is not suitable from the perspective of cost control. The method provided by this disclosure mainly uses deactivated titanium-silicon molecular sieve catalysts as raw materials, turning waste into treasure, thereby saving costs.

[0052] In the preferred embodiments described above, the discharge agent of each device is measured independently based on the reaction of each device. As long as it is ensured that, under the same reaction conditions in the same device, the activity of the discharge agent is lower than that of the fresh catalyst, it is considered the discharge agent of the present invention. As mentioned above, preferably, the activity of the discharge agent is less than 50% of the activity of the fresh catalyst.

[0053] In the above preferred embodiments, taking the discharge agent of the cyclohexanone ammonium oxime reaction device as an example, the activity is determined by the following method:

[0054] TS-1 molecular sieve (prepared according to the method described in "Zeolites, 1992, Vol. 12: 943-950, with a TiO2 mass percentage of 2.1%) was placed in a 100 mL slurry bed reactor equipped with a continuous feed and membrane separation device. Under stirring, a mixture of water and 30 wt% hydrogen peroxide (volume ratio of water to hydrogen peroxide of 10:9) was added at a rate of 5.7 mL / h, a mixture of cyclohexanone and tert-butanol (volume ratio of cyclohexanone and tert-butanol of 1:2.5) was added at a rate of 10.5 mL / h, and 36 wt% ammonia was added at a rate of 5.7 mL / h. The three material streams were added simultaneously and discharged continuously at the corresponding rates. The reaction temperature was maintained at 80 °C. After the reaction stabilized, the product was sampled every 1 h, and the composition of the liquid phase was analyzed by gas chromatography. The conversion rate of cyclohexanone was calculated using the following formula and used as the activity of the titanium silicate molecular sieve. The conversion rate of cyclohexanone is calculated as follows: [(molar amount of added cyclohexanone - molar amount of unreacted cyclohexanone) / molar amount of added cyclohexanone] × 100%. The result from the first hour is taken as the initial activity.

[0055] In the preferred embodiments described above, the titanium-silicon molecular sieve can be a common titanium-silicon molecular sieve with various topologies. For example, the titanium-silicon molecular sieve can be selected from one or more of the following: MFI structure titanium-silicon molecular sieves (such as TS-1), MEL structure titanium-silicon molecular sieves (such as TS-2), BEA structure titanium-silicon molecular sieves (such as Ti-Beta), MWW structure titanium-silicon molecular sieves (such as Ti-MCM-22), hexagonal structure titanium-silicon molecular sieves (such as Ti-MCM-41, Ti-SBA-15), MOR structure titanium-silicon molecular sieves (such as Ti-MOR), TUN structure titanium-silicon molecular sieves (such as Ti-TUN), and other structures of titanium-silicon molecular sieves (such as Ti-ZSM-48). Preferably, the titanium-silicon molecular sieve is selected from one or more of the following: MFI structure titanium-silicon molecular sieves, MEL structure titanium-silicon molecular sieves, and BEA structure titanium-silicon molecular sieves. More preferably, the titanium-silicon molecular sieve is an MFI structure titanium-silicon molecular sieve, such as TS-1 molecular sieve.

[0056] In the preferred embodiments described above, the weight ratio of the first discharge agent, titanium source, aluminum source, organic acid, alkali source, and water can be 100:(0.1-10):(0.1-10):(0.005-50):(0.5-50):(20-1000), preferably 100:(0.5-10):(0.5-10):(1-15):(1-20):(100-800), and more preferably, the weight ratio of the first discharge agent to the organic acid is 100:(2-8), wherein the first discharge agent is calculated as SiO2, and the organic acid is calculated as H2O. + When the alkali source contains nitrogen, it is calculated as N; when the alkali source does not contain nitrogen, it is calculated as OH. - The molar ratio of the silicon source (calculated as SiO2) to the titanium source (calculated as TiO2) can be (5-20):1.

[0057] In the preferred embodiments described above, the aluminum source is a substance capable of providing aluminum. Preferably, the aluminum source is aluminum sol, aluminum salt, aluminum hydroxide, or aluminum oxide. The aluminum sol preferably has a content of 10-50% by weight, calculated as aluminum oxide. The aluminum salt can be an inorganic aluminum salt and / or an organic aluminum salt. The organic aluminum salt is preferably a C1-C10 organic aluminum salt. The inorganic aluminum salt can be, for example, aluminum sulfate, sodium aluminate, aluminum chloride, or aluminum nitrate.

[0058] In the preferred embodiment described above, step (2) can be performed as follows: first, the aluminum source and the alkali source are mixed in the presence of an aqueous solvent to obtain a mixed solution; then, the mixed solution is mixed with the first solid, the silicon source, and the titanium source, followed by the second heat treatment. This can further improve the activity of the titanium-silicon-aluminum molecular sieve.

[0059] The preferred embodiment described above may further include a step of recovering the product from the material after the second heat treatment in step (2). The product recovery step is a conventional method, well known to those skilled in the art, and is not particularly required here. It generally refers to the process of product filtration, washing, drying, and calcination. The drying process can be carried out at a temperature between 20-200°C, and the calcination process can be carried out at a temperature between 300-800°C, first in a nitrogen atmosphere for 0.5-6 hours and then in an air atmosphere for 3-12 hours.

[0060] Alternatively, according to another preferred embodiment of this disclosure, the preparation steps of the titanium-silicon-aluminum molecular sieve include:

[0061] a. The second discharge agent is mixed with an organic acid solution and slurried, and the resulting slurry is subjected to a third heat treatment to separate the second solid. The second discharge agent is the discharge agent of the reaction device with silica-alumina molecular sieve as the catalyst active component. The conditions of the third heat treatment are: temperature of 50-150℃, time of 0.5-40h, preferably 1-24h, more preferably 10-20h.

[0062] b. The second solid, silicon source, titanium source and alkali source are mixed in the presence of an aqueous solvent and then subjected to a fourth heat treatment. The conditions for the fourth heat treatment are: temperature of 100-200℃, preferably 120-180℃, more preferably 140-170℃, and time of 0.5-25h, preferably 2-24h, more preferably 5-20h.

[0063] In the preferred embodiment described above, the relative crystallinity of the second solid obtained after the third heat treatment can be 50-70%. Under specific third heat treatment conditions, the second discharge agent can be processed into a second solid with a specific relative crystallinity, and then subjected to a fourth heat treatment to obtain a titanium-silicon-aluminum molecular sieve with excellent catalytic performance. This sieve can further improve the selectivity of propylene glycol monomethyl ether in the reaction disclosed herein. The method for determining the relative crystallinity is as described above.

[0064] In the preferred embodiments described above, the specific definition of the discharge agent is as previously stated, except that the titanium-silicon molecular sieve is replaced with a silica-alumina molecular sieve. The discharge agent of the reaction device using a silica-alumina molecular sieve as the catalyst active component can be a discharge agent discharged from various devices using silica-alumina molecular sieves as the catalyst active component. For example, it can be a discharge agent discharged from a synthesis reaction device using silica-alumina molecular sieves as the catalyst active component (such as a discharge agent from a synthesis reaction device for hydrogen sulfide and methanol), or a discharge agent discharged from a catalytic cracking reaction device using silica-alumina molecular sieves as the catalyst active component. Preferably, the discharge agent is a catalyst deactivated under alkaline conditions. Therefore, for this disclosure, the second discharge agent is preferably a discharge agent from a synthesis reaction device for hydrogen sulfide and methanol (such as deactivated silica-alumina molecular sieve ZSM-5, powder, with a particle size of 100-500 nm).

[0065] As mentioned above, in a preferred embodiment, the activity of the second discharge agent is less than 50% of the activity of the silica-alumina molecular sieve when it is fresh.

[0066] In the above preferred embodiments, taking the discharge agent of the hydrogen sulfide and methanol synthesis reaction apparatus as an example, the activity is determined by the following method:

[0067] ZSM-5 molecular sieve (prepared according to the method described in Example 1 of Chinese Patent CN1715185A) was steam-treated at 200℃ for 10 hours, then pressed into tablets, sieved, and 20-40 mesh particles were packed into a tubular reaction tube with a diameter of 0.8 cm and a length of 55 cm. The catalyst particle bed volume was 2.0 cm³. 3 The reaction was carried out at a temperature of 300℃, a pressure of 1 atm, a feed molar ratio of hydrogen sulfide to methanol of 1:2, and a total gas hourly space velocity of 700 h⁻¹. -1Under the specified conditions, a catalytic reaction for the synthesis of dimethyl sulfide was carried out. The product obtained after 3 hours of catalytic reaction was analyzed by gas chromatography. The methanol conversion rate was calculated based on the analytical results and used as the activity of the silica-alumina molecular sieve. Methanol conversion rate = [(molar amount of added methanol - molar amount of unreacted methanol) / molar amount of added methanol] × 100%. The result from the first hour was taken as the initial activity.

[0068] In the preferred embodiments described above, the aluminosilicate molecular sieve can be a common aluminosilicate molecular sieve with various topologies. Preferably, the aluminosilicate molecular sieve is selected from at least one of the following: MFI structured aluminosilicate molecular sieve, FAU structured aluminosilicate molecular sieve, MWW structured aluminosilicate molecular sieve, MEL structured aluminosilicate molecular sieve, and BEA structured aluminosilicate molecular sieve. More preferably, the aluminosilicate molecular sieve is at least one of the following: MFI structured aluminosilicate molecular sieve, BEA structured aluminosilicate molecular sieve, and MWW structured aluminosilicate molecular sieve.

[0069] In the preferred embodiment described above, the weight ratio of the second discharge agent, titanium source, organic acid, alkali source, and water is 100:(0.1-10):(0.005-50):(0.5-50):(20-1000), preferably 100:(0.5-10):(1-15):(1-20):(100-800), and more preferably the weight ratio of the second discharge agent to the organic acid is 100:(2-8), wherein the second discharge agent is calculated as SiO2, and the organic acid is calculated as H2O. + When the alkali source contains nitrogen, it is calculated as N; when the alkali source does not contain nitrogen, it is calculated as OH. - The molar ratio of the silicon source (calculated as SiO2) to the titanium source (calculated as TiO2) can be (5-20):1.

[0070] In the preferred embodiment described above, preferred step (b) is performed as follows: the aqueous solution containing the alkali source is mixed with the second solid, the silicon source, and the titanium source, and then the fourth heat treatment is performed.

[0071] In the preferred embodiments for preparing the above two types of titanium-silicon-aluminum molecular sieves, the pulping is preferably carried out at room temperature and pressure. Unless otherwise specified, heat treatment is generally carried out under autogenous pressure in a sealed environment.

[0072] In the preferred embodiments of the above two methods for preparing titanium-silicon-aluminum molecular sieves, there are no special requirements for the organic acid; it can be a C1-C10 organic carboxylic acid, preferably a cycloalkanoic acid, peracetic acid, or perpropionic acid. Preferably, the concentration of the organic acid solution is >0.1 mol / L, more preferably ≥1 mol / L, and even more preferably 2-15 mol / L. In this disclosure, the main solvent of the acid solution is water, but other solvents and additives may be added as needed. The titanium-silicon-aluminum molecular sieve prepared in this way exhibits better catalytic performance.

[0073] In the preferred embodiments of the above two preparation methods of titanium-silicon-aluminum molecular sieves, the silicon source can be an inorganic silicon source and / or an organosilicon source. The inorganic silicon source can be a silicate, silica sol, or silica gel. The organosilicon source can be an organosilicon ester selected from those shown in Formula I.

[0074]

[0075] In Formula I, R1, R2, R3, and R4 are each C1-C4 alkyl groups, including straight-chain alkyl groups of C1-C4 and branched alkyl groups of C3-C4. For example, R1, R2, R3, and R4 can each be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, or tert-butyl. Preferably, the silicon source is an organosilicate, such as methyl orthosilicate, ethyl orthosilicate, propyl orthosilicate, or butyl orthosilicate.

[0076] In the preferred embodiments of the above two preparation methods of titanium-silicon-aluminum molecular sieves, the titanium source can be an organic titanium source (e.g., an organic titanate ester) and / or an inorganic titanium source (e.g., an inorganic titanium salt). The inorganic titanium source can be TiCl4, Ti(SO4)2, TiOCl2, titanium hydroxide, titanium oxide, titanium nitrate, or titanium phosphate, while the organic titanium source can be a fatty alcohol titanium and / or an organic titanate ester. The titanium source is preferably an organic titanium source, and more preferably an organic titanate ester. The organic titanate ester is preferably an organic titanate ester with the structural formula M4TiO4, wherein M is preferably an alkyl group having 1-4 carbon atoms, and the four M's can be the same or different. Preferably, the organic titanate ester is isopropyl titanate, n-propyl titanate, tetrabutyl titanate, or tetraethyl titanate. Specific examples of the titanium source may include, but are not limited to: TiOCl2, titanium tetrachloride, titanium sulfate, tetrapropyl titanate (including various isomers of tetrapropyl titanate, such as tetraisopropyl titanate and tetran-propyl titanate), tetrabutyl titanate (various isomers of tetrabutyl titanate, such as tetran-butyl titanate), and tetraethyl titanate, etc.

[0077] In the preferred embodiments of the above two methods for preparing titanium-silicon-aluminum molecular sieves, the range of selectable alkali sources is relatively wide, and they can be organic alkali sources and / or inorganic alkali sources. The inorganic alkali source can be ammonia, or an alkali with an alkali metal or alkaline earth metal cation, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, barium hydroxide, etc. The organic alkali source can be urea, aliphatic amines, aliphatic alcoholic amines, or quaternary ammonium compounds. The quaternary ammonium base can be various organic quaternary ammonium bases. The aliphatic amine can be a compound formed by replacing at least one hydrogen atom in various NH3 groups with an aliphatic hydrocarbon group (preferably alkyl). The aliphatic alcoholic amine can be a compound formed by replacing at least one hydrogen atom in various NH3 groups with a hydroxyl-containing aliphatic hydrocarbon group (preferably alkyl).

[0078] Specifically, the quaternary ammonium base can be a quaternary ammonium base as shown in Formula II, the aliphatic amine can be an aliphatic amine represented by Formula III, and the aliphatic alcoholic amine can be an aliphatic alcoholic amine represented by Formula IV.

[0079]

[0080] In Formula II, R5, R6, R7 and R8 are each C1-C4 alkyl groups, including straight-chain alkyl groups of C1-C4 and branched alkyl groups of C3-C4. For example, R5, R6, R7 and R8 can each be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl.

[0081] R 9 (NH2) n (Formula III)

[0082] In Equation III, n is an integer of 1 or 2. When n is 1, R 9 It is a C1-C6 alkyl group, including straight-chain alkyl groups of C1-C6 and branched alkyl groups of C3-C6, such as 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, R 9 It is a C1-C6 alkylene compound, including straight-chain alkylene compounds of C1-C6 and branched alkylene compounds of C3-C6, such as methylene, ethylene, n-propylene, n-butylene, n-pentylene, or n-hexylene. More preferably, the aliphatic amine compound is ethylamine, n-butylamine, butanediamine, or hexamethylenediamine.

[0083] (HOR 10 ) m NH (3-m) (Formula IV)

[0084] In equation IV, m R 10 Whether identical or different, each is a C1-C4 alkylene compound, including C1-C4 straight-chain alkylene compounds and C3-C4 branched alkylene compounds, such as methylene, ethylene, n-propylene, and n-butylene; m is 1, 2, or 3. More preferably, the aliphatic alkanolamine compound is monoethanolamine, diethanolamine, or triethanolamine.

[0085] Most preferably, the alkali source is sodium hydroxide, ammonia, ethylenediamine, n-butylamine, butanediamine, hexamethylenediamine, monoethanolamine, diethanolamine, triethanolamine, tetraethylammonium hydroxide, or tetrapropylammonium hydroxide. When the alkali source contains ammonia, the molar ratio of the alkali source includes both molecular form NH3 and ionic form NH4. + Ammonia meter present.

[0086] In the preferred embodiments of the preparation of the above two titanium-silicon-aluminum molecular sieves, the alkali source is preferably provided in the form of an alkaline solution, and more preferably the pH of the alkaline solution is >9.

[0087] In the preferred embodiments of the above two titanium-silicon-aluminum molecular sieve preparations, the aqueous solvent is primarily water, but a co-solvent may be added as needed. In the embodiments disclosed herein, the aqueous solvent is water.

[0088] According to the method of this disclosure, after the second reaction is completed, the reaction product can be separated by ordinary distillation or rectification. Unreacted propylene and other substances do not need to be separated and purified, and can be directly returned to the reaction apparatus to continue the reaction.

[0089] The present disclosure will be further illustrated by the following examples, but these examples do not limit the scope of the disclosure.

[0090] In the preparation example, the X-ray diffraction (XRD) phase pattern of the sample was determined on a Siemens D5005 X-ray diffractometer.

[0091] In the examples and comparative examples, all reagents used were commercially available chemically pure reagents. The titanium-silicon molecular sieve TS-1 used was prepared according to the method described in the prior art, Zeolites, 1992, Vol. 12, pages 943-950. The silica-alumina molecular sieve ZSM-5 used was prepared according to the method of Example 1 in Chinese Patent CN1715185A.

[0092] The reaction products were analyzed by gas chromatography, and the results were quantified using the correction and normalization method. The chromatographic conditions were as follows: Agilent-6890N chromatograph, FFAP capillary column, injection volume 0.5 μL, injection port temperature 180℃. Column temperature was maintained at 100℃ for 2 min, then increased to 200℃ at a rate of 15℃ / min and held for 3 min. FID detector, detector temperature 200℃.

[0093] In the various embodiments and comparative examples:

[0094] When the molar ratio of propylene to oxidant is ≤1, the relative conversion rate of propylene (%) = (molar amount of propylene in the feed - molar amount of unreacted propylene) / molar amount of propylene in the feed × 100%;

[0095] When the molar ratio of propylene to oxidant is >1, the relative conversion rate of propylene (%) = (molar amount of propylene in the feed - molar amount of unreacted propylene) / molar amount of propylene in the feed × molar amount of propylene in the feed / molar amount of oxidant in the feed × 100%.

[0096] Selectivity of MME-1 (%) = (moles of MME-1 in the reaction product / moles of propylene oxide consumed in the reaction) × 100%;

[0097] Selectivity of MME-2 (%) = (moles of MME-2 in the reaction product / moles of propylene oxide consumed in the reaction) × 100%.

[0098] Preparation Example 1

[0099] (1) Take TS-1 molecular sieve (prepared according to the method described in "Zeolites, 1992, Vol. 12: 943-950", with a TiO2 mass percentage of 2.1%) and place it in a 100 mL slurry bed reactor with continuous feed and membrane separation device. Under stirring, add a mixture of water and 30 wt% hydrogen peroxide (volume ratio of water to hydrogen peroxide is 10:9) at a rate of 5.7 mL / h, add a mixture of cyclohexanone and tert-butanol (volume ratio of cyclohexanone and tert-butanol is 1:2.5) at a rate of 10.5 mL / h, and add 36 wt% ammonia water at a rate of 5.7 mL / h. The above three material streams are added simultaneously and discharged continuously at the corresponding rates. The reaction temperature is maintained at 80℃. After the reaction stabilizes, the product is sampled every 1 h and the composition of the liquid phase is analyzed by gas chromatography. The conversion rate of cyclohexanone is calculated using the following formula and used as the activity of the titanium silicate molecular sieve. The conversion rate of cyclohexanone is calculated as [(molar amount of added cyclohexanone - molar amount of unreacted cyclohexanone) / molar amount of added cyclohexanone] × 100%. The initial activity of cyclohexanone, measured in the first hour, is 99.5%. After approximately 168 hours, the conversion rate of cyclohexanone decreases from the initial 99.5% to 50%. The catalyst is then separated and regenerated by calcination (calcined at 570°C in air for 4 hours). It is then used again in the cyclohexanone ammonium oxime reaction. This step is repeated until the activity after regeneration is less than 50% of the initial activity. The deactivated ammonium oxime catalyst sample is used as the discharge agent in this preparation example. Discharge agents SH-1 (activity 40%), SH-2 (activity 25%), and SH-3 (activity 10%) are obtained sequentially according to the aforementioned method.

[0100] (2) At room temperature (20℃, the same below) and atmospheric pressure (0.1MPa, the same below), the deactivated cyclohexanone oxime catalyst SH-1 was first mixed with a 1mol / L naphthenic acid aqueous solution and slurryed. Then, the slurry was mixed and stirred at 45℃ for a first heat treatment of 12h. After solid-liquid separation, the solid (relative crystallinity of 71%), silicon source methyl orthosilicate, aluminum source aluminum sulfate, titanium source titanium sulfate and sodium hydroxide aqueous solution (pH 12) were mixed and the mixture was placed in a stainless steel sealed reactor and subjected to a second heat treatment at 170℃ for 12h. The mass composition of the materials was deactivated cyclohexanone oxime catalyst: titanium source: aluminum source: acid: alkali: water = 100: 1: 1: 2: 5: 250. The deactivated cyclohexanone oxime catalyst was calculated as SiO2 and the acid was calculated as H2O. + Calculated, alkali is OH - The molar ratio of silicon source (SiO2) to titanium source (TiO2) was 10:1. The obtained product was filtered, washed with water, dried at 110℃ for 120 min, and then calcined at 550℃ for 3 h to obtain a molecular sieve. Its XRD phase diagram showed that a titanium-silicon-aluminum molecular sieve (TS-A) with an MFI structure was obtained.

[0101] (3) Under normal temperature and pressure, the deactivated cyclohexanone oximation catalyst SH-2 was first mixed with a 5 mol / L peracetic acid solution and slurryed. Then, the mixture was stirred at 20°C and subjected to a first heat treatment for 20 h. After solid-liquid separation, the solid (relative crystallinity of 89%), silicon source tetraethyl orthosilicate, aluminum source aluminum sol (content of 20 wt%), titanium source tetrabutyl titanate, and tetrapropylammonium hydroxide aqueous solution (pH of 10) were mixed and placed in a stainless steel sealed reactor. A second heat treatment was carried out at 150°C for 20 h. The mass composition of the materials was deactivated cyclohexanone oximation catalyst: titanium source: aluminum source: acid: alkali: water = 100: 2: 0.5: 8: 15: 200. The deactivated cyclohexanone oximation catalyst was calculated as SiO2, and the acid was calculated as H2O. + Calculated, alkali is OH - The molar ratio of silicon source (SiO2) to titanium source (TiO2) was 20:1. The product was then recovered according to step (2) to obtain titanium-silicon-aluminum molecular sieve, whose XRD phase diagram showed that titanium-silicon-aluminum molecular sieve (TS-B) with MFI structure was obtained.

[0102] (4) Under normal temperature and pressure, the deactivated cyclohexanone oxime catalyst SH-3 was mixed with an 8 mol / L peroxypropionic acid aqueous solution and slurryed. The mixture was then stirred at 30°C and subjected to a first heat treatment for 10 h. After solid-liquid separation, the solid (relative crystallinity of 80%), silicon source propyl orthosilicate, aluminum source aluminum hydroxide, titanium source titanium tetrachloride, and ethylenediamine aqueous solution (pH 11) were mixed and placed in a stainless steel sealed reactor for a second heat treatment at 140°C for 5 h. The mass composition of the materials was: deactivated cyclohexanone oxime catalyst: titanium source: aluminum source: acid: alkali: water = 100: 5: 2: 5: 5: 150. The deactivated cyclohexanone oxime catalyst was calculated as SiO2, and the acid was calculated as H2O. + The molar ratio of silicon source (calculated as N, SiO2, and titanium source (calculated as TiO2)) to alkali source (calculated as N) was 15:1. The product was then recovered according to step (2) to obtain titanium-silicon-aluminum molecular sieve, whose XRD phase diagram showed that titanium-silicon-aluminum molecular sieve (TS-C) with MFI structure was obtained.

[0103] (5) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4), except that the temperature of the first heat treatment was 60°C, the relative crystallinity of the solid after solid-liquid separation was 65%, and the XRD phase diagram showed that titanium silicate aluminum molecular sieve (TS-D) with MFI structure was obtained.

[0104] (6) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4), except that the temperature of the first heat treatment was 180°C, the relative crystallinity of the solid after solid-liquid separation was 95%, and the XRD phase diagram showed that titanium silicate aluminum molecular sieve (TS-E) with MFI structure was obtained.

[0105] (7) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4), except that the peroxypropionic acid aqueous solution was replaced with formic acid. After solid-liquid separation, the relative crystallinity of the solid was 60%, and the XRD phase diagram showed that titanium silicate aluminum molecular sieve (TS-F) with MFI structure was obtained.

[0106] (8) Titanium silicate alumina molecular sieves were prepared according to the method in step (4), except that the deactivated cyclohexanone oxime catalyst: acid = 100:15, the relative crystallinity of the solid after solid-liquid separation was 62%, and the XRD phase diagram showed that titanium silicate alumina molecular sieves (TS-G) with MFI structure were obtained.

[0107] (9) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4). The difference was that TS-1 molecular sieve (relative crystallinity of 100%), silicon source propyl orthosilicate, aluminum source aluminum hydroxide, titanium source titanium tetrachloride and ethylenediamine aqueous solution were directly mixed and subjected to a second heat treatment. The XRD crystal phase diagram showed that titanium silicate aluminum molecular sieve (TS-H) with MFI structure was obtained.

[0108] Preparation Example 2

[0109] (1) ZSM-5 molecular sieve (prepared according to the method described in Example 1 of Chinese Patent CN1715185A) was steam-treated at 200℃ for 10 hours, then pressed into tablets, sieved, and 20-40 mesh particles were packed into a tubular reaction tube with a diameter of 0.8 cm and a length of 55 cm. The catalyst particle bed volume was 2.0 cm³. 3 The reaction was carried out at a temperature of 300℃, a pressure of 1 atm, a feed molar ratio of hydrogen sulfide to methanol of 1:2, and a total gas hourly space velocity of 700 h⁻¹. -1 Under certain conditions, a catalytic reaction for the synthesis of dimethyl sulfide was carried out. The product obtained after 3 hours of catalytic reaction was analyzed by gas chromatography. The methanol conversion rate was calculated based on the analysis results and used as the activity of the silica-alumina molecular sieve. Methanol conversion rate = [(molar amount of added methanol - molar amount of unreacted methanol) / molar amount of added methanol] × 100%. The result of the first hour was taken as the initial activity, which was 99%. After approximately 180 hours, the methanol conversion rate decreased from the initial 99% to 50%. The catalyst was then separated and regenerated by calcination (calcined at 570°C in air for 4 hours). It was then used again in the synthesis reaction of hydrogen sulfide and methanol. This step was repeated until the regenerated activity was less than 50% of the initial activity. The deactivated catalyst sample was used as the discharge agent of this invention. Discharge agents SH-I (activity 45%), SH-II (activity 35%), and SH-III (activity 15%) were obtained sequentially according to the aforementioned method.

[0110] (2) At room temperature (20℃, the same below) and atmospheric pressure (0.1MPa, the same below), the deactivated catalyst SH-I was first mixed with a 1mol / L naphthenic acid aqueous solution and slurryed. Then, the slurry was mixed and stirred at 50℃ for a third heat treatment of 12h. After solid-liquid separation, the solid (relative crystallinity of 70%), silicon source methyl orthosilicate, titanium source titanium sulfate and sodium hydroxide aqueous solution (pH 12) were mixed and the mixture was placed in a stainless steel sealed reactor and subjected to a fourth heat treatment at 170℃ for 12h. The mass composition of the materials was deactivated catalyst: titanium source: acid: alkali: water = 100: 1: 2: 5: 250. The deactivated catalyst was calculated as SiO2 and the acid was calculated as H2O. + Calculated, alkali is OH - The molar ratio of silicon source (SiO2) to titanium source (TiO2) was 10:1. The obtained product was filtered, washed with water, dried at 110℃ for 120 min, and then calcined at 550℃ for 3 h to obtain a molecular sieve. Its XRD phase diagram showed that a titanium-silicon-aluminum molecular sieve (SA-A) with an MFI structure was obtained.

[0111] (3) Under normal temperature and pressure, the deactivated catalyst SH-II was first mixed with a 5 mol / L peracetic acid solution and slurryed. Then, the mixture was stirred at 150°C and subjected to a third heat treatment for 20 h. After solid-liquid separation, the solid (relative crystallinity of 53%), silicon source tetraethyl orthosilicate, titanium source tetrabutyl titanate, and tetrapropylammonium hydroxide aqueous solution (pH 10) were mixed and placed in a stainless steel sealed reactor for a fourth heat treatment at 150°C for 20 h. The mass composition of the materials was deactivated catalyst: titanium source: acid: alkali: water = 100: 2: 8: 15: 200. The deactivated cyclohexanone oxime catalyst was calculated as SiO2, and the acid was calculated as H2O. + Calculated, alkali is OH - The molar ratio of silicon source (SiO2) to titanium source (TiO2) was 20:1. The product was then recovered according to step (2) to obtain titanium-silicon-aluminum molecular sieve, whose XRD phase diagram showed that titanium-silicon-aluminum molecular sieve (SA-B) with MFI structure was obtained.

[0112] (4) Under normal temperature and pressure, the deactivated catalyst SH-III was mixed with an 8 mol / L peroxypropionic acid aqueous solution and slurryed. The mixture was then stirred at 100°C for 10 h. After solid-liquid separation, the solid (relative crystallinity 61%), silicon source propyl orthosilicate, titanium source titanium tetrachloride, and ethylenediamine aqueous solution (pH 11) were mixed and placed in a stainless steel sealed reactor. The mixture was then hydrothermally treated at 140°C for 5 h. The mass composition of the materials was deactivated catalyst: titanium source: acid: alkali: water = 100: 5: 5: 5: 150. The deactivated catalyst was calculated as SiO2, and the acid was calculated as H2O. + The molar ratio of silicon source (calculated as N, SiO2, and titanium source (calculated as TiO2)) to alkali source (calculated as N) was 15:1. The product was then recovered according to step (2) to obtain titanium-silicon-aluminum molecular sieve, whose XRD phase diagram showed that titanium-silicon-aluminum molecular sieve (SA-C) with MFI structure was obtained.

[0113] (5) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4), except that the temperature of the third heat treatment was 40°C, the relative crystallinity of the solid after solid-liquid separation was 41%, and the XRD phase diagram showed that titanium silicate aluminum molecular sieve (SA-D) with MFI structure was obtained.

[0114] (6) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4), except that the temperature of the third heat treatment was 180℃, the relative crystallinity of the solid after solid-liquid separation was 80%, and the XRD phase diagram showed that titanium silicate aluminum molecular sieve (SA-E) with MFI structure was obtained.

[0115] (7) Titanium silicate aluminum molecular sieves were prepared according to the method in step (4), except that the peroxypropionic acid aqueous solution was replaced with formic acid. After solid-liquid separation, the relative crystallinity of the solid was 38%, and the XRD phase diagram showed that titanium silicate aluminum molecular sieves (SA-F) with MFI structure were obtained.

[0116] (8) Titanium silicate alumina molecular sieves were prepared according to the method in step (4), except that the deactivated catalyst: acid = 100: 20, the relative crystallinity of the solid after solid-liquid separation was 30%, and the XRD phase diagram showed that titanium silicate alumina molecular sieves (SA-G) with MFI structure were obtained.

[0117] (9) Titanium silicate aluminum molecular sieve was prepared according to the method in step (4). The difference was that ZSM-5 molecular sieve (relative crystallinity of 100%), titanium tetrachloride source and ethylenediamine aqueous solution were directly mixed and subjected to the fourth heat treatment. The XRD crystal phase diagram showed that titanium silicate aluminum molecular sieve (SA-H) with MFI structure was obtained.

[0118] Example 1

[0119] Propylene, methanol, 12% hydrogen peroxide (wt%), and the first catalyst (titanium silicate molecular sieve TS-1) were added to a reactor at a molar ratio of propylene, hydrogen peroxide, and methanol of 1:1:25 and a weight ratio of propylene to the first catalyst of 100:15. The first reaction was carried out at 60°C and 1.5 MPa for 1 hour. Then, the second catalyst (TS-A) was added, with a weight ratio of propylene to the second catalyst of 100:30. The second reaction was carried out at 60°C and 1.5 MPa for 5 hours. The results are shown in Table 1.

[0120] Example 2

[0121] Propylene, methanol, 12% hydrogen peroxide (wt%), and the first catalyst (titanium silicate molecular sieve TS-1) were added to a reactor at a molar ratio of propylene, hydrogen peroxide, and methanol of 1:0.5:15 and a weight ratio of propylene to the first catalyst of 100:5. The first reaction was carried out at 60°C and 1.5 MPa for 1 hour. Then, the second catalyst (TS-A) was added, with a weight ratio of propylene to the second catalyst of 100:15. The second reaction was carried out at 60°C and 1.5 MPa for 3 hours. The results are shown in Table 1.

[0122] Example 3

[0123] Propylene, methanol, 12% hydrogen peroxide (wt%), and the first catalyst (titanium silicate molecular sieve TS-1) were added to a reactor at a molar ratio of propylene, hydrogen peroxide, and methanol of 1:5:100 and a weight ratio of propylene to the first catalyst of 100:2. The first reaction was carried out at 50°C and 1.5 MPa for 1 hour. Then, the second catalyst (TS-A) was added, with a weight ratio of propylene to the second catalyst of 100:5. The second reaction was carried out at 60°C and 1.0 MPa for 5 hours. The results are shown in Table 1.

[0124] Example 4

[0125] Propylene, methanol, 12% hydrogen peroxide (wt%), and the first catalyst (titanium silicate molecular sieve TS-1) were added to a reactor at a molar ratio of propylene, hydrogen peroxide, and methanol of 1:0.1:10.5 and a weight ratio of propylene to the first catalyst of 100:100. The first reaction was carried out at 40°C and 1.5 MPa for 1 hour. Then, the second catalyst (TS-A) was added, with a weight ratio of propylene to the second catalyst of 100:150. The second reaction was carried out at 60°C and 0.5 MPa for 5 hours. The results are shown in Table 1.

[0126] Example 5

[0127] Propylene, methanol, 12% hydrogen peroxide (wt%), and the first catalyst (titanium silicate molecular sieve TS-1) were added to a reactor at a molar ratio of propylene, hydrogen peroxide, and methanol of 1:1:20 and a weight ratio of propylene to the first catalyst of 100:15. The first reaction was carried out at 60°C and 1.5 MPa for 1 hour. Then, the second catalyst (TS-A) was added, with a weight ratio of propylene to the second catalyst of 100:30. The second reaction was carried out at 60°C and 1.5 MPa for 10 hours. The results are shown in Table 1.

[0128] Example 6

[0129] Propylene, methanol, 12% hydrogen peroxide (wt%), and the first catalyst (titanium silicate molecular sieve TS-1) were added to a reactor at a molar ratio of propylene, hydrogen peroxide, and methanol of 1:1:40 and a weight ratio of propylene to the first catalyst of 100:15. The first reaction was carried out at 60°C and 1.5 MPa for 1 h. Then, the second catalyst (TS-A) was added, with a weight ratio of propylene to the second catalyst of 100:30. The second reaction was carried out at 60°C and 1.5 MPa for 0.1 h. The results are shown in Table 1.

[0130] Examples 7-13

[0131] Propylene glycol monomethyl ether was prepared according to the method in Example 1, except that the catalyst was replaced with TS-B, TS-C, TS-D, TS-E, TS-F, TS-G and TS-H respectively. The reaction results are shown in Table 1.

[0132] Examples 14-21

[0133] Propylene glycol monomethyl ether was prepared according to the method in Example 1, except that the catalyst was replaced with SA-A, SA-B, SA-C, SA-D, SA-E, SA-F, SA-G and SA-H respectively. The reaction results are shown in Table 1.

[0134] Example 22

[0135] Propylene glycol monomethyl ether was prepared according to the method of Example 1, except that in the second reaction, the same amount of titanium silicate aluminate molecular sieve prepared according to Example 1 of CN102616805A was used instead of the second catalyst (TS-A). The reaction results are shown in Table 1.

[0136] Comparative Example 1

[0137] Propylene glycol monomethyl ether was prepared according to the method in Example 1, except that no catalyst (TS-A) was used for the second reaction; that is, only the first reaction was carried out. The results are shown in Table 1.

[0138] Comparative Example 2

[0139] Propylene glycol monomethyl ether was prepared according to the method in Example 1, except that in the second reaction, the same amount of titanium silicate molecular sieve TS-1 was used instead of the second catalyst (TS-A). The results are shown in Table 1.

[0140] Comparative Example 3

[0141] Propylene glycol monomethyl ether was prepared according to the method in Example 1, except that in the second reaction, the same amount of silica-alumina molecular sieve ZSM-5 was used instead of the second catalyst (TS-A). The results are shown in Table 1.

[0142] Comparative Example 4

[0143] Propylene glycol monomethyl ether was prepared according to the method of Comparative Example 1, except that the reaction temperature was 80℃. The results are shown in Table 1.

[0144] Comparative Example 5

[0145] Propylene glycol monomethyl ether was prepared according to the method of Comparative Example 1, except that the molar ratio of propylene, hydrogen peroxide and methanol was 1:1:10. The results are shown in Table 1.

[0146] Table 1

[0147]

[0148] The above results confirm that the method disclosed herein for oxidizing propylene can achieve a high propylene conversion rate and a high selectivity for 2-methoxy-1-propanol (MME-2) in the product propylene glycol monomethyl ether, demonstrating good catalytic oxidation activity and stability of the catalyst. A comparison of Example 1 and Comparative Examples 1-4 shows that, compared to not performing the second reaction or not using a catalyst containing titanium silicate molecular sieves in the second reaction, the method disclosed herein can significantly improve the relative conversion rate of propylene and the selectivity for 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether. A comparison of Example 1 and Comparative Example 5 shows that when the molar ratio of propylene, oxidant, and methanol is 1:(0.1-10):(10.5-100), the method disclosed herein can improve the relative conversion rate of propylene and the selectivity for 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether. A comparison of Examples 1 and 5-6 shows that when the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1:(0.2-5), the relative conversion of propylene and the selectivity of 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether can be further improved. A comparison of Examples 1, 7-13, and 14-22 shows that the titanium silicate aluminate molecular sieve prepared by a specific method is beneficial for obtaining a higher relative conversion of propylene and a higher selectivity of 2-methoxy-1-propanol (MME-2) in propylene glycol monomethyl ether when used in the reaction.

[0149] The preferred embodiments of this disclosure have been described in detail above. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0150] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0151] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for propylene oxidation, characterized in that, The method includes the following steps: S1. Propylene, oxidant and methanol are subjected to a first reaction in the presence of a first catalyst to obtain a first reaction mixture, wherein the first catalyst contains titanium silicate molecular sieve. S2. The first reaction mixture is mixed with the second catalyst to carry out the second reaction, wherein the second catalyst contains titanium silicon aluminum molecular sieve; The molar ratio of propylene, oxidant, and methanol is 1:(0.2-5):(15-80); the weight ratio of propylene, the first catalyst, and the second catalyst is 100:(5-500):(10-100); the oxidant is hydrogen peroxide; the ratio of the reaction time of the first reaction to the reaction time of the second reaction is 1:(0.2-5); the conditions for the first reaction are: temperature 30-60℃ and pressure 1-1.5MPa; the conditions for the second reaction are: temperature 30-60℃ and pressure 1-1.5MPa. The preparation steps of the titanium-silicon-aluminum molecular sieve include: (1) The first discharge agent is mixed with an organic acid solution and slurryed, and the resulting slurry is subjected to a first heat treatment to separate the first solid. The first discharge agent is the discharge agent of the reaction device with titanium-silicon molecular sieve as the catalyst active component. The conditions of the first heat treatment are: temperature of 20-45℃ and time of 1-30h. The discharge agent of the reaction device with titanium-silicon molecular sieve as the catalyst active component is the discharge agent of the cyclohexanone ammonium oxime reaction device. (2) The first solid, silicon source, aluminum source, titanium source and alkali source are mixed in the presence of an aqueous solvent and then subjected to a second heat treatment. The conditions for the second heat treatment are: temperature of 100-200℃ and time of 0.5-25h. The weight ratio of the first discharge agent, titanium source, aluminum source, organic acid, alkali source, and water is 100:(0.1-10):(0.1-10):(0.005-50):(0.5-50):(20-1000), where the first discharge agent is calculated as SiO2 and the organic acid is calculated as H2O. + When the alkali source contains nitrogen, it is calculated as N; when the alkali source does not contain nitrogen, it is calculated as OH. - The molar ratio of the silicon source (calculated as SiO2) to the titanium source (calculated as TiO2) is (5-20):1; the concentration of the organic acid solution is greater than 0.1 mol / L. Alternatively, the preparation steps of the titanium-silicon-aluminum molecular sieve include: a. The second discharge agent is mixed with an organic acid solution and slurried. The resulting slurry is then subjected to a third heat treatment to separate the second solid. The second discharge agent is a discharge agent from a reaction device using a silica-alumina molecular sieve as the catalyst active component. The conditions for the third heat treatment are: temperature 50-150℃, time 0.5-40h. The discharge agent from the reaction device using a silica-alumina molecular sieve as the catalyst active component is a discharge agent from a reaction device for synthesizing dimethyl sulfide from hydrogen sulfide and methanol. b. The second solid, silicon source, titanium source and alkali source are mixed in the presence of an aqueous solvent and then subjected to a fourth heat treatment. The conditions for the fourth heat treatment are: temperature of 100-200℃ and time of 0.5-25h. The organic acid is a naphthenic acid, peracetic acid, or perpropionic acid; The weight ratio of the second discharge agent, titanium source, organic acid, alkali source, and water is 100:(0.1-10):(0.005-50):(0.5-50):(20-1000), where the second discharge agent is calculated as SiO2 and the organic acid is calculated as H2O. + When the alkali source contains nitrogen, it is calculated as N; when the alkali source does not contain nitrogen, it is calculated as OH. - The molar ratio of the silicon source (calculated as SiO2) to the titanium source (calculated as TiO2) is (5-20):1; the concentration of the organic acid solution is greater than 0.1 mol / L.

2. The method according to claim 1, wherein, The titanium-silicon molecular sieve is an MFI type titanium-silicon molecular sieve, a MEL type titanium-silicon molecular sieve, an MWW type titanium-silicon molecular sieve, a hexagonal titanium-silicon molecular sieve, or an MRE type titanium-silicon molecular sieve. The titanium-silicon-aluminum molecular sieve is an MFI structure titanium-silicon-aluminum molecular sieve, a MEL structure titanium-silicon-aluminum molecular sieve, a BEA structure titanium-silicon-aluminum molecular sieve, a MWW structure titanium-silicon-aluminum molecular sieve, a MOR structure titanium-silicon-aluminum molecular sieve, a TUN structure titanium-silicon-aluminum molecular sieve, or a two-dimensional hexagonal structure titanium-silicon-aluminum molecular sieve.

3. The method according to claim 1, wherein, The titanium-silicon molecular sieve in step (1) is an MFI structure titanium-silicon molecular sieve, and the activity of the first discharge agent is less than 50% of the activity of the titanium-silicon molecular sieve when it is fresh.

4. The method according to claim 1, wherein, In step (2), the aluminum source and the alkali source are first mixed in the presence of an aqueous solvent to obtain a mixed solution, and then the mixed solution is mixed with the first solid and the titanium source before the second heat treatment is performed.

5. The method according to claim 1, wherein, The silica-aluminum molecular sieve in step a is an MFI structure silica-aluminum molecular sieve, and the activity of the second discharge agent is less than 50% of the activity of the silica-aluminum molecular sieve when it is fresh.

6. The method according to claim 1, wherein, The alkali source is ammonia, aliphatic amine, aliphatic alcohol amine, or quaternary ammonium base; the aluminum source is aluminum sol, aluminum salt, aluminum hydroxide, or aluminum oxide; the titanium source is inorganic titanium salt and / or organic titanate; and the silicon source is organic silicate.

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