Method for oxidizing styrene into styrene oxide

Abstract

The invention relates to the technical field of preparation of chemical intermediates, in particular to a method for oxidizing styrene into styrene oxide. The preparation method comprises the following steps: adding 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of a main catalyst, 115 parts by mass of an auxiliary agent and 520 parts by mass of styrene into a stainless steel kettle, and starting stirring; controlling the reaction temperature to be 25-30 DEG C, and starting to dropwise add 500 parts by mass of H2O2; after dripping, stirring for 30 minutes, stopping stirring, sampling, performing chromatographic analysis and the like. The manganese element is introduced into the precursor solvent to prepare the main catalyst, in the process, compounding of manganese acetate and an iron element compound can be spontaneously promoted, more mesopores are formed by uniformly embedding and dispersing in a nitrogen-doped mesoporous carbon material, and the abundant mesopores and carbon edge defects can also promote better combination of the main catalyst and the material, so that the catalytic activity of the catalyst is improved. Therefore, the main catalyst has better catalytic activity, and the yield of styrene converted into styrene oxide is improved.

Description

Technical Field

[0001] The invention relates to the technical field of chemical intermediate preparation, and in particular to a method for oxidizing styrene to produce styrene oxide. Background Art

[0002] Epoxystyrene, also known as styrene oxide, is a liquid compound with an aromatic odor. It can be used as an epoxy resin diluent, UV absorber, flavor enhancer, etc. It is also an important intermediate in organic synthesis, pharmaceutical and fragrance industries. It is widely used in the production of β-phenylethanol, drug anthelmintics, levamisole, phenylacetaldehyde and other flavors and sweeteners.

[0003] The prior art generally utilizes HTS titanium silicalite catalyst to catalyze the conversion of styrene into styrene oxide. The HTS titanium silicalite catalyst is a powder of titanium silicalite with an MFI structure. Although the HTS titanium silicalite catalyst has the function of catalyzing the oxidation of styrene, the preparation process of the HTS titanium silicalite catalyst is relatively complicated and expensive. In addition, due to the specificity of the HTS titanium silicalite catalyst to the catalytic reaction, its regeneration process is complicated and requires specific regeneration conditions and techniques. Therefore, in the actual production process, the HTS titanium silicalite catalyst is often reused, or used HTS titanium silicalite catalyst is purchased due to cost reasons. Repeated use will reduce the structural stability of the HTS titanium silicalite catalyst, thereby reducing the catalytic activity of the HTS titanium silicalite catalyst, affecting the yield and purity of styrene oxide. Therefore, the present application proposes a method for oxidizing styrene to styrene oxide, using a main catalyst with a simple preparation process and high catalytic activity to solve the above problems. Summary of the invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for oxidizing styrene to styrene oxide.

[0005] A method for oxidizing styrene to styrene oxide comprises the following steps:

[0006] S1: Add 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of primary catalyst, 115 parts by mass of auxiliary agent and 520 parts by mass of styrene into a stainless steel kettle, and start stirring;

[0007] S2: Control the reaction temperature at 25-30°C and start adding 500 parts by mass of H2O2;

[0008] S3: Stir for 30 minutes after the dripping is completed, stop stirring, take samples, and perform chromatographic analysis;

[0009] S4: Start stirring in the stainless steel kettle, add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then dropwise add 50 parts by mass of H2O2, and control the dropping temperature at 25-30°C;

[0010] S5: After the dripping is completed, stop stirring, let the mixture stand to separate into layers, take samples for chromatographic analysis, and when the reaction is complete, separate the organic phase, evaporate the water phase under reduced pressure, and reuse the remaining water phase.

[0011] Further, step S1: adding 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of main catalyst, 115 parts by mass of auxiliary agent and 520 parts by mass of styrene into a stainless steel kettle, and starting stirring; specifically comprising the following steps:

[0012] S1.1: Add melamine and polyvinyl pyrrolidone in a mass ratio of 1:4 to 50 parts by volume of N,N-dimethylformamide and stir magnetically for 5 minutes to obtain a mixed solution.

[0013] S1.2: Then 2.4-3 parts by mass of ferric nitrate is dissolved in 50 parts by volume of the mixed solution and stirred for 1 hour to obtain a precursor solvent;

[0014] S1.3: Dissolve manganese acetate in the precursor solvent at a solid-liquid ratio of (1-2):50; continue stirring at 150°C until N,N-dimethylformamide is completely evaporated.

[0015] S1.4: Pyrolyze the obtained precursor powder at 800°C for 2h in an argon atmosphere to obtain a main catalyst;

[0016] S1.5: at 8m 3 In a stainless steel kettle, 800 parts by mass of water and 630 parts by mass of urea, 1.15 parts by mass of a main catalyst, 115 parts by mass of an auxiliary agent and 520 parts by mass of styrene were added, and stirring was started.

[0017] Further, step S3: stirring for 30 minutes after the dripping is completed, stopping the stirring and taking samples, and chromatographic analysis; specifically comprising the following steps:

[0018] S3.1: After dripping H2O2, set the stirring speed to 600-700r / min, stir for 30min, stop stirring, use a pump to take samples of 1-2g at the bottom, 1 / 2 height and surface of the material in the stainless steel kettle, mix the samples evenly, and obtain the sample;

[0019] S3.2: Perform chromatographic analysis on the sample. The specific chromatographic conditions are: SE-30 capillary column, 30m×0.53m×1um; carrier gas is N2, flow rate is 30mL / min; the temperature of the vaporization chamber is 250℃; the temperature of the detector is 250℃; column temperature: 180℃, programmed temperature, starting temperature is 50℃, keep warm for 1min, and heat to 180℃ at 10℃ / min. Calculate the purity of styrene oxide.

[0020] Further, step S4: start stirring in the stainless steel kettle, add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then dropwise add 50 parts by mass of H2O2, and control the dropping temperature at 25°C to 30°C; specifically includes the following steps:

[0021] S4.1: 4-4.5 parts by weight of macroporous silica gel, 0.42-0.45 parts by weight of aluminum nitrate, 0.2-0.25 parts by weight of seed crystals, 4.5-5 parts by weight of n-propylamine and 5.3-5.5 parts by weight of deionized water are mixed and ground for 30-35 minutes, then placed in a high-pressure crystallization reactor, and crystallized in an oven at a temperature of 180-185° C. for 30-50 minutes;

[0022] S4.2: After crystallization, the mixture is dried and ground, and then heated to 550°C in a muffle furnace at a rate of 5°C / min and maintained for 3 hours to obtain HZSM-5 molecular sieve;

[0023] S4.3: EDTA is loaded on the HZSM-5 molecular sieve by an equal volume impregnation method, EDTA and HZSM-5 molecular sieve are mixed in a ratio of 1:1, and impregnated at room temperature for 14 hours to obtain a stabilizer, and the stabilizer is mixed with NaOH in a ratio of 1:10 to obtain a stabilizing aid;

[0024] S4.4: Start stirring in the stainless steel kettle at a speed of 500-600r / min, then add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then drop 50 parts by mass of H2O2. During the drop addition, control the temperature in the stainless steel kettle to 25-30°C, and the drop addition time is 1-2h.

[0025] Further, step S5: after the dripping is completed, stirring is stopped, the mixture is allowed to stand for stratification, and sampling is performed for chromatographic analysis. The reaction is completed when the content of styrene oxide is 98.31%. The organic phase is separated, water is evaporated under reduced pressure in the water phase, and the remaining water phase is reused; the steps specifically include:

[0026] After S5.1 was added, stirring in the stainless steel kettle was stopped, and the mixture was allowed to stand for 30-60 minutes until the materials in the stainless steel kettle were separated into layers. Samples were taken at the center of the organic phase for chromatographic analysis. The specific chromatographic conditions were as follows: SE-30 capillary column, 30m×0.53m×1um; carrier gas was N2, flow rate was 30mL / min; temperature of the vaporization chamber was 250℃; temperature of the detector was 250℃; column temperature was 180℃, programmed temperature was used, starting temperature was 50℃, heat preservation was performed for 1 minute, and the temperature was increased to 180℃ at a rate of 10℃ / min. The purity of styrene oxide was calculated.

[0027] S5.2: Separation operation to separate the organic phase and the aqueous phase, the organic phase is styrene oxide;

[0028] S5.3: The separated water phase is subjected to reduced pressure distillation until the volume of the water phase is one third of the original volume to obtain recycled water, which is mixed with deionized water and used in step S1 to complete the recycling of the water phase.

[0029] Furthermore, in step S1.4, the heating rate is 5°C / min.

[0030] Furthermore, in step S1.5, the stirring speed is 500-600 r / min.

[0031] Furthermore, in step S1.1, the auxiliary agent is one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and ammonium bicarbonate.

[0032] Furthermore, in step S4.1, the grinding speed is 800-1000 r / min.

[0033] Furthermore, in step S4.2, the drying condition is 60° C. for 40 min.

[0034] Compared with the prior art, the present invention has at least the following beneficial effects:

[0035] 1. The present invention prepares the main catalyst by introducing manganese into the precursor solvent. In this process, manganese acetate and iron compounds can be spontaneously promoted to recombine and uniformly embedded in the dispersed and nitrogen-doped mesoporous carbon material to form more mesopores. This process is simple and low in cost. The abundant mesopores and carbon edge defects can also promote better combination of the main catalyst and the material. At the same time, the formed hierarchical pores can promote the catalytic process of oxygen evolution reaction and hydrogen evolution reaction, so that the main catalyst has better catalytic activity and improves the yield of styrene conversion to styrene oxide.

[0036] 2. The present invention forms a stabilizer by loading EDTA on HZSM-5 molecular sieve. EDTA has good stability for urea peroxidation reaction, can effectively prevent urea from self-decomposition, thereby ensuring the progress of the reaction and reducing the amount of urea added, saving costs, and the HZSM-5 molecular sieve can weaken the interaction between the active metal components and the carrier, so that EDTA and the metal components in the material will not accumulate due to molecular repulsion, but can be evenly dispersed, thereby fully contacting with urea, playing a better stabilizing role, preventing insufficient reaction, so that styrene can be completely converted into styrene oxide, and the purity of the styrene oxide product is improved.

[0037] 3. The present invention uses urea peroxidation to form peroxyurea, and uses peroxyurea to oxidize styrene to generate styrene oxide. This reaction can more specifically convert styrene into styrene oxide, reduce the generation of by-products, and improve the purity of the product. In addition, this method is simple in process, environmentally friendly, and does not produce waste water or waste residue. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate embodiments of the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and to enable those skilled in the relevant art to make and use the present disclosure.

[0039] Figure 1 The present invention is a flowchart of a method for oxidizing styrene to styrene oxide used in an embodiment of the present invention. DETAILED DESCRIPTION

[0040] The following is a detailed description of a method for oxidizing styrene to styrene oxide provided by the present invention in conjunction with the accompanying drawings and specific embodiments. At the same time, it is explained here that in order to make the embodiments more detailed, the following embodiments are the best and preferred embodiments, and those skilled in the art may also adopt other alternatives to implement some known technologies; and the accompanying drawings are only for more specific description of the embodiments, and are not intended to specifically limit the present invention.

[0041] Embodiment 1:

[0042] A method for oxidizing styrene to styrene oxide, such as Figure 1 As shown, the following steps are included:

[0043] S1: 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of the main catalyst, 115 parts by mass of the auxiliary agent sodium hydroxide and 520 parts by mass of styrene were added into a stainless steel kettle, and stirring was started.

[0044] S1.1: Add melamine and polyvinyl pyrrolidone in a mass ratio of 1:4 to 50 parts by volume of N,N-dimethylformamide and stir magnetically for 5 minutes to obtain a mixed solution.

[0045] S1.2: Then 2.4 parts by mass of ferric nitrate is dissolved in 50 parts by volume of the mixed solution and stirred for 1 hour to obtain a precursor solvent;

[0046] S1.3: Dissolve manganese acetate in the precursor solvent at a solid-liquid ratio of 1:50; continue stirring at 150°C until N,N-dimethylformamide is completely evaporated.

[0047] S1.4: The obtained precursor powder is pyrolyzed at 800°C in an argon atmosphere at a heating rate of 5°C / min for 2h to obtain a main catalyst;

[0048] S1.5: at 8m 3 In a stainless steel kettle, 800 parts by mass of water and 630 parts by mass of urea, 1.15 parts by mass of main catalyst, 115 parts by mass of auxiliary agent, and 520 parts by mass of styrene were added, and stirring was started at a speed of 500 r / min.

[0049] S2: Control the reaction temperature to 25°C and start adding 500 parts by mass of H2O2 dropwise.

[0050] S3: Stir for 30 minutes after the dropwise addition is completed, stop stirring, take samples, and perform chromatographic analysis.

[0051] S3.1: After dripping H2O2, set the stirring speed to 600r / min, stir for 30min, stop stirring, use a pump to take samples of 1g each at the bottom, 1 / 2 height and surface of the material in the stainless steel kettle, mix the samples evenly, and obtain the sample;

[0052] S3.2: Perform chromatographic analysis on the sample. The specific chromatographic conditions are: SE-30 capillary column, 30m×0.53m×1um; carrier gas is N2, flow rate is 30mL / min; the temperature of the vaporization chamber is 250℃; the temperature of the detector is 250℃; column temperature: 180℃, programmed temperature, starting temperature is 50℃, keep warm for 1min, increase the temperature to 180℃ at 10℃ / min, calculate the purity of styrene oxide, and the purity of styrene oxide is 94.17%.

[0053] S4: Start stirring in the stainless steel kettle, add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then dropwise add 50 parts by mass of H2O2, and control the dropping temperature at 25°C.

[0054] S4.1: 4 parts by mass of macroporous silica gel, 0.42 parts by mass of aluminum nitrate, 0.2 parts by mass of seed crystals, 4.5 parts by mass of n-propylamine and 5.3 parts by mass of deionized water were mixed and ground for 30 min at a grinding speed of 800 r / min, and then placed in a high-pressure crystallization reactor and crystallized in an oven at a temperature of 180°C for 30 min;

[0055] S4.2: drying after crystallization, the drying condition is 60°C for 40 min, grinding, and then heating to 550°C in a muffle furnace at a rate of 5°C / min and maintaining for 3 h to obtain HZSM-5 molecular sieve;

[0056] S4.3: EDTA is loaded on the HZSM-5 molecular sieve by an equal volume impregnation method, EDTA and HZSM-5 molecular sieve are mixed in a ratio of 1:1, and impregnated at room temperature for 14 hours to obtain a stabilizer, and the stabilizer is mixed with NaOH in a ratio of 1:10 to obtain a stabilizing aid;

[0057] S4.4: Start stirring in the stainless steel kettle at a speed of 500r / min, then add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then drop 50 parts by mass of H2O2. During the drop addition, control the temperature in the stainless steel kettle to 25°C and the drop addition time to be 1h.

[0058] S5: After the dripping is completed, stop stirring, let the mixture stand to separate into layers, take samples for chromatographic analysis, and when the reaction is complete, separate the organic phase, evaporate the water phase under reduced pressure, and reuse the remaining water phase.

[0059] After S5.1 was added, stirring in the stainless steel kettle was stopped, and the mixture was allowed to stand for 30 minutes until the materials in the stainless steel kettle were separated into layers. Samples were taken at the center of the organic phase for chromatographic analysis. The specific chromatographic conditions were: SE-30 capillary column, 30m×0.53m×1um; carrier gas was N2, flow rate was 30mL / min; temperature of the vaporization chamber was 250°C; temperature of the detector was 250°C; column temperature was 180°C, programmed temperature was used, the starting temperature was 50°C, the temperature was kept for 1 minute, and the temperature was increased to 180°C at 10°C / min. The purity of styrene oxide was calculated, and the purity of styrene oxide was 98.31%;

[0060] S5.2: Separation operation to separate the organic phase and the aqueous phase, the organic phase is styrene oxide;

[0061] S5.3: The separated water phase is subjected to reduced pressure distillation until the volume of the water phase is one third of the original volume to obtain recycled water, which is mixed with deionized water and used in step S1 to complete the recycling of the water phase.

[0062] Embodiment 2:

[0063] A method for oxidizing styrene to styrene oxide, such as Figure 1 As shown, the following steps are included:

[0064] S1: 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of the main catalyst, 115 parts by mass of the auxiliary agent sodium hydroxide and 520 parts by mass of styrene were added into a stainless steel kettle, and stirring was started.

[0065] S1.1: Add melamine and polyvinyl pyrrolidone in a mass ratio of 1:4 to 50 parts by volume of N,N-dimethylformamide and stir magnetically for 5 minutes to obtain a mixed solution.

[0066] S1.2: Then 3 parts by mass of ferric nitrate is dissolved in 50 parts by volume of the mixed solution and stirred for 1 hour to obtain a precursor solvent;

[0067] S1.3: Dissolve manganese acetate in the precursor solvent at a solid-liquid ratio of 2:50; continue stirring at 150°C until N,N-dimethylformamide is completely evaporated.

[0068] S1.4: The obtained precursor powder is pyrolyzed at 800°C in an argon atmosphere at a heating rate of 5°C / min for 2h to obtain a main catalyst;

[0069] S1.5: at 8m 3 In a stainless steel kettle, 800 parts by mass of water and 630 parts by mass of urea, 1.15 parts by mass of main catalyst, 115 parts by mass of auxiliary agent, and 520 parts by mass of styrene were added, and stirring was started at a speed of 500 r / min.

[0070] S2: Control the reaction temperature to 25°C and start adding 500 parts by mass of H2O2 dropwise.

[0071] S3: Stir for 30 minutes after the dropwise addition is completed, stop stirring, take samples, and perform chromatographic analysis.

[0072] S3.1: After dripping H2O2, set the stirring speed to 600r / min, stir for 30min, stop stirring, use a pump to take 2g samples from the bottom, 1 / 2 height and surface of the material in the stainless steel kettle, mix the samples evenly, and obtain the sample;

[0073] S3.2: Perform chromatographic analysis on the sample. The specific chromatographic conditions are: SE-30 capillary column, 30m×0.53m×1um; carrier gas is N2, flow rate is 30mL / min; the temperature of the vaporization chamber is 250℃; the temperature of the detector is 250℃; column temperature: 180℃, programmed temperature, starting temperature is 50℃, keep warm for 1min, increase the temperature to 180℃ at 10℃ / min, calculate the purity of styrene oxide, and the purity of styrene oxide is 93.89%.

[0074] S4: Start stirring in the stainless steel kettle, add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then dropwise add 50 parts by mass of H2O2, and control the dropping temperature at 25°C.

[0075] S4.1: 4.5 parts by mass of macroporous silica gel, 0.52 parts by mass of aluminum nitrate, 0.25 parts by mass of seed crystals, 5 parts by mass of n-propylamine and 5.5 parts by mass of deionized water were mixed and ground for 30 min at a grinding speed of 800 r / min, and then placed in a high-pressure crystallization reactor and crystallized in an oven at a temperature of 180°C for 30 min;

[0076] S4.2: drying after crystallization, the drying condition is 60°C for 40 min, grinding, and then heating to 550°C in a muffle furnace at a rate of 5°C / min and maintaining for 3 h to obtain HZSM-5 molecular sieve;

[0077] S4.3: EDTA is loaded on the HZSM-5 molecular sieve by an equal volume impregnation method, EDTA and HZSM-5 molecular sieve are mixed in a ratio of 1:1, and impregnated at room temperature for 14 hours to obtain a stabilizer, and the stabilizer is mixed with NaOH in a ratio of 1:10 to obtain a stabilizing aid;

[0078] S4.4: Start stirring in the stainless steel kettle at a speed of 500r / min, then add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then drop 50 parts by mass of H2O2. During the drop addition, control the temperature in the stainless steel kettle to 25°C and the drop addition time to be 1h.

[0079] S5: After the dripping is completed, stop stirring, let the mixture stand to separate into layers, take samples for chromatographic analysis, and when the reaction is complete, separate the organic phase, evaporate the water phase under reduced pressure, and reuse the remaining water phase.

[0080] After S5.1 was added, stirring in the stainless steel kettle was stopped, and the mixture was allowed to stand for 30 minutes until the materials in the stainless steel kettle were separated into layers. Samples were taken at the center of the organic phase for chromatographic analysis. The specific chromatographic conditions were: SE-30 capillary column, 30m×0.53m×1um; carrier gas was N2, flow rate was 30mL / min; temperature of the vaporization chamber was 250°C; temperature of the detector was 250°C; column temperature was 180°C, programmed temperature was used, the starting temperature was 50°C, the temperature was kept for 1 minute, and the temperature was increased to 180°C at 10°C / min. The purity of styrene oxide was calculated, and the purity of styrene oxide was 98.05%.

[0081] S5.2: Separation operation to separate the organic phase and the aqueous phase, the organic phase is styrene oxide;

[0082] S5.3: The separated water phase is subjected to reduced pressure distillation until the volume of the water phase is one third of the original volume to obtain recycled water, which is mixed with deionized water and used in step S1 to complete the recycling of the water phase.

[0083] Embodiment 3:

[0084] A method for oxidizing styrene to styrene oxide, such as Figure 1 As shown, the following steps are included:

[0085] S1: 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of the main catalyst, 115 parts by mass of the auxiliary agent sodium hydroxide and 520 parts by mass of styrene were added into a stainless steel kettle, and stirring was started.

[0086] S1.1: Add melamine and polyvinyl pyrrolidone in a mass ratio of 1:4 to 50 parts by volume of N,N-dimethylformamide and stir magnetically for 5 minutes to obtain a mixed solution.

[0087] S1.2: Then 2.4 parts by mass of ferric nitrate is dissolved in 50 parts by volume of the mixed solution and stirred for 1 hour to obtain a precursor solvent;

[0088] S1.3: Dissolve manganese acetate in the precursor solvent at a solid-liquid ratio of 1:50; continue stirring at 150°C until N,N-dimethylformamide is completely evaporated.

[0089] S1.4: The obtained precursor powder is pyrolyzed at 800°C in an argon atmosphere at a heating rate of 5°C / min for 2h to obtain a main catalyst;

[0090] S1.5: at 8m 3 In a stainless steel kettle, 800 parts by mass of water and 630 parts by mass of urea, 1.15 parts by mass of main catalyst, 115 parts by mass of auxiliary agent, and 520 parts by mass of styrene were added, and stirring was started at a speed of 600 r / min.

[0091] S2: The reaction temperature was controlled at 30°C and 500 parts by mass of H2O2 were started to be added dropwise.

[0092] S3: Stir for 30 minutes after the dropwise addition is completed, stop stirring, take samples, and perform chromatographic analysis.

[0093] S3.1: After dripping H2O2, set the stirring speed to 600r / min, stir for 30min, stop stirring, use a pump to take samples of 1g each at the bottom, 1 / 2 height and surface of the material in the stainless steel kettle, mix the samples evenly, and obtain the sample;

[0094] S3.2: Perform chromatographic analysis on the sample. The specific chromatographic conditions are: SE-30 capillary column, 30m×0.53m×1um; carrier gas is N2, flow rate is 30mL / min; the temperature of the vaporization chamber is 250℃; the temperature of the detector is 250℃; column temperature: 180℃, programmed temperature, starting temperature is 50℃, keep warm for 1min, increase the temperature to 180℃ at 10℃ / min, calculate the purity of styrene oxide, and the purity of styrene oxide is 93.61%.

[0095] S4: Start stirring in the stainless steel kettle, add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then dropwise add 50 parts by mass of H2O2, and control the dropping temperature at 30°C.

[0096] S4.1: 4 parts by mass of macroporous silica gel, 0.42 parts by mass of aluminum nitrate, 0.2 parts by mass of seed crystals, 4.5 parts by mass of n-propylamine and 5.3 parts by mass of deionized water were mixed and ground for 30 min at a grinding speed of 1000 r / min, and then placed in a high-pressure crystallization kettle and crystallized in an oven at a temperature of 180°C for 30 min;

[0097] S4.2: drying after crystallization, the drying condition is 60°C for 40 min, grinding, and then heating to 550°C in a muffle furnace at a rate of 5°C / min and maintaining for 3 h to obtain HZSM-5 molecular sieve;

[0098] S4.3: EDTA is loaded on the HZSM-5 molecular sieve by an equal volume impregnation method, EDTA and HZSM-5 molecular sieve are mixed in a ratio of 1:1, and impregnated at room temperature for 14 hours to obtain a stabilizer, and the stabilizer is mixed with NaOH in a ratio of 1:10 to obtain a stabilizing aid;

[0099] S4.4: Start stirring in the stainless steel kettle at a speed of 500r / min, then add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then drop 50 parts by mass of H2O2. During the drop addition, control the temperature in the stainless steel kettle at 30°C and the drop addition time is 2h.

[0100] S5: After the dripping is completed, stop stirring, let the mixture stand to separate into layers, take samples for chromatographic analysis, and when the reaction is complete, separate the organic phase, evaporate the water phase under reduced pressure, and reuse the remaining water phase.

[0101] After S5.1 was added, stirring in the stainless steel kettle was stopped, and the mixture was allowed to stand for 60 minutes until the materials in the stainless steel kettle were separated into layers. Samples were taken at the center of the organic phase for chromatographic analysis. The specific chromatographic conditions were: SE-30 capillary column, 30m×0.53m×1um; carrier gas was N2, flow rate was 30mL / min; temperature of the vaporization chamber was 250°C; temperature of the detector was 250°C; column temperature was 180°C, programmed temperature was used, the starting temperature was 50°C, the temperature was kept for 1 minute, and the temperature was increased to 180°C at 10°C / min. The purity of styrene oxide was calculated, and the purity of styrene oxide was 97.92%.

[0102] S5.2: Separation operation to separate the organic phase and the aqueous phase, the organic phase is styrene oxide;

[0103] S5.3: The separated water phase is subjected to reduced pressure distillation until the volume of the water phase is one third of the original volume to obtain recycled water, which is mixed with deionized water and used in step S1 to complete the recycling of the water phase.

[0104] Comparative Example 1:

[0105] Compared with Example 1, the difference of Comparative Example 1 is that in step S1, steps 1.1-1.4 are not performed, manganese acetate is directly used as the main catalyst, and the remaining steps remain unchanged, specifically:

[0106] "S1.5: at 8m 3 In a stainless steel kettle, 800 parts by mass of water and 630 parts by mass of urea, 1.15 parts by mass of manganese acetate, 115 parts by mass of auxiliary sodium hydroxide and 520 parts by mass of styrene were added, stirring was started, the yield of styrene oxide was calculated, and the purity of styrene oxide in step S5 was tested.

[0107] Comparative Example 2:

[0108] Compared with Example 1, the difference of Comparative Example 2 is that step S4 does not perform steps S4.1-S4.3, and directly uses NaOH and EDTA as stabilizing agents, specifically: "S4.4: Mix EDTA and NaOH in a volume ratio of 1:10 to obtain a stabilizing agent, start stirring in a stainless steel kettle at a stirring speed of 500r / min, then add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then add 50 parts by mass of H2O2 dropwise, control the temperature in the stainless steel kettle to 25°C during the dropwise addition, and the dropping time is 1h", calculate the yield of styrene oxide, and test the purity of styrene oxide in step S5.

[0109] Comparative Example 3:

[0110] Comparative Example 3 is commercially available styrene oxide.

[0111] Comparative Example 4:

[0112] Comparative Example 4 is to use the HTS titanium silicon molecular sieve catalyst used for the first time as a catalyst to convert styrene oxide. The specific steps refer to the invention patent with publication number CN102993130A, and the yield and purity of styrene oxide are calculated.

[0113] Comparative Example 5:

[0114] Comparative Example 5 is to use the HTS titanium silicon molecular sieve catalyst sold for the second time as a catalyst to convert styrene oxide. The specific steps refer to the invention patent with publication number CN102993130A, and the yield and purity of styrene oxide are calculated.

[0115] The purity of commercially available styrene oxide in Comparative Example 3 was tested.

[0116] The yields of styrene oxide of Examples 1-3 were calculated, and the purity of styrene oxide of Examples 1-3 was statistically analyzed, as shown in Table 1.

[0117] Table 1

[0118]

[0119] In the table, the yields of Examples 1-3 are all 90%, and the purity I and purity II are two tests in step S3 and after the preparation is completed. The highest purity of Example 1 is 98.31%, and the purity in step S3 is 94.17%; the highest purity of Example 2 is 98.05%, and the purity in step S3 is 93.89%; the highest purity of Example 3 is 97.92%, and the purity in step S3 is 93.61%; it can be seen that Example 1 is the optimal condition and ratio for oxidizing styrene to styrene oxide.

[0120] The yield of Comparative Example 1 is 85%, the purity I is 90.56%, and the purity II is 95.15%, because manganese acetate is not treated but used directly. Although manganese acetate has a catalytic effect, its own structure does not have a good contact surface with other materials, and its catalytic activity is general. Therefore, the yield and purity of Comparative Example 1 are not as good as those of the embodiment.

[0121] The yield of Comparative Example 2 is 87%, the purity I is 94.13%, and the purity II is 95.33%. The purity I of Comparative Example 2 is almost the same as that of Example 1 because the steps of Comparative Example 2 before testing the purity I are no different from those of Example 1. Subsequently, since EDTA is not treated but directly mixed with NaOH as an auxiliary agent and then added, EDTA and NaOH react to form EDTA-Na and other metal complexes, thereby reducing the stabilizing effect of EDTA on urea and causing insufficient reaction completion, resulting in a decrease in the yield of styrene oxide.

[0122] Comparative Example 3 is a commercially available product. It can be seen that the purity of the commercially available product is 98%, which is not much different from the purity of the product of the present invention. It can be seen that the product of the present invention can meet market demand.

[0123] The yield of comparative example 4 is 87%, and purity II is the final purity, 97.95%. It can be seen that the main catalyst and method provided by the present invention have a higher yield, and in terms of purity, examples 1 and 2 can also surpass the purity of comparative example 4.

[0124] The yield of comparative example 5 is 72%, and the final purity II is 93.61%. It can be seen that the yield and purity of the HTS titanium silicon molecular sieve catalyst used for secondary sales are significantly lower than those of the first use, and are not as good as the embodiments of the present invention.

[0125] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.

Claims

1. A method for oxidizing styrene to styrene oxide, characterized in that: The steps include: S1: Add 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of primary catalyst, 115 parts by mass of auxiliary agent and 520 parts by mass of styrene into a stainless steel kettle, and start stirring; S2: Control the reaction temperature at 25-30°C and start adding 500 parts by mass of H2O2; S3: Stir for 30 min after the dripping is completed, stop stirring, take samples, and perform chromatographic analysis; S4: Start stirring in the stainless steel kettle, add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then dropwise add 50 parts by mass of H2O2, and control the dropping temperature at 25-30°C; S5: After the dripping is completed, stop stirring, let stand and separate into layers, take samples, perform chromatographic analysis, and when the reaction is complete, separate the organic phase, evaporate the water phase under reduced pressure, and reuse the remaining water phase.

2. A method for oxidizing styrene to styrene oxide according to claim 1, characterized in that: Step S1: adding 800 parts by mass of water, 630 parts by mass of urea, 1.15 parts by mass of primary catalyst, 115 parts by mass of auxiliary agent and 520 parts by mass of styrene into a stainless steel kettle, and starting stirring; comprising the following steps: S1.1: Add melamine and polyvinyl pyrrolidone in a mass ratio of 1:4 to 50 parts by volume of N,N-dimethylformamide and stir magnetically for 5 minutes to obtain a mixed solution. S1.2: Then 2.4-3 parts by mass of ferric nitrate is dissolved in 50 parts by volume of the mixed solution and stirred for 1 hour to obtain a precursor solvent; S1.3: Dissolve manganese acetate in the precursor solvent at a solid-liquid ratio of (1-2):50; continue stirring at 150°C until N,N-dimethylformamide is completely evaporated. S1.4: Pyrolyze the obtained precursor powder at 800°C for 2h in an argon atmosphere to obtain a main catalyst; S1.5: at 8m 3 In a stainless steel kettle, 800 parts by mass of water and 630 parts by mass of urea, 1.15 parts by mass of a main catalyst, 115 parts by mass of an auxiliary agent and 520 parts by mass of styrene were added, and stirring was started.

3. A method for oxidizing styrene to styrene oxide according to claim 2, characterized in that: Step S4: Stirring is started in a stainless steel kettle, and then 50 parts by weight of urea, 10 parts by weight of a stabilizing agent, and then 50 parts by weight of H2O2 are added dropwise, and the dropping temperature is controlled at 25°C to 30°C; comprising the following steps: S4.1: 4-4.5 parts by weight of macroporous silica gel, 0.42-0.45 parts by weight of aluminum nitrate, 0.2-0.25 parts by weight of seed crystals, 4.5-5 parts by weight of n-propylamine and 5.3-5.5 parts by weight of deionized water are mixed and ground for 30-35 minutes, then placed in a high-pressure crystallization reactor, and crystallized in an oven at a temperature of 180-185° C. for 30-50 minutes; S4.2: After crystallization, the mixture is dried and ground, and then heated to 550°C in a muffle furnace at a rate of 5°C / min and maintained for 3 hours to obtain HZSM-5 molecular sieve; S4.3: EDTA is loaded on the HZSM-5 molecular sieve by an equal volume impregnation method, EDTA and HZSM-5 molecular sieve are mixed in a ratio of 1:1, and impregnated at room temperature for 14 hours to obtain a stabilizer, and the stabilizer is mixed with NaOH in a ratio of 1:10 to obtain a stabilizing aid; S4.4: Start stirring in the stainless steel kettle at a speed of 500-600r / min, then add 50 parts by mass of urea, 10 parts by mass of stabilizing agent, and then drop 50 parts by mass of H2O2. During the drop addition, control the temperature in the stainless steel kettle to 25-30°C, and the drop addition time is 1-2h.

4. A method for oxidizing styrene to styrene oxide according to claim 3, characterized in that: Step S3: Stir for 30 minutes after the dripping is completed, stop stirring, take samples, and perform chromatographic analysis; comprising the following steps: S3.1: After dripping H2O2, set the stirring speed to 600-700r / min, stir for 30min, stop stirring, use a pump to take samples of 1-2g at the bottom, 1 / 2 height and surface of the material in the stainless steel kettle, mix the samples evenly, and obtain the sample; S3.2: Perform chromatographic analysis on the sample. The specific chromatographic conditions are: SE-30 capillary column, 30m×0.53m×1um; carrier gas is N2, flow rate is 30mL / min; the temperature of the vaporization chamber is 250℃; the temperature of the detector is 250℃; column temperature: 180℃, programmed temperature, starting temperature is 50℃, keep warm for 1min, and heat to 180℃ at 10℃ / min. Calculate the purity of styrene oxide.

5. A method for oxidizing styrene to styrene oxide according to claim 4, characterized in that: Step S5: After the dripping is completed, stirring is stopped, the mixture is allowed to stand for stratification, and sampling is performed for chromatographic analysis. The reaction is completed when the content of styrene oxide is 98.31%. The organic phase is separated, and water is evaporated under reduced pressure in the aqueous phase. The remaining aqueous phase is reused; the steps include: After S5.1 was added, stirring in the stainless steel kettle was stopped, and the mixture was allowed to stand for 30-60 minutes until the materials in the stainless steel kettle were separated into layers. Samples were taken at the center of the organic phase for chromatographic analysis. The specific chromatographic conditions were as follows: SE-30 capillary column, 30m×0.53m×1um; carrier gas was N2, flow rate was 30mL / min; temperature of the vaporization chamber was 250℃; temperature of the detector was 250℃; column temperature was 180℃, programmed temperature was used, starting temperature was 50℃, heat preservation was performed for 1 minute, and the temperature was increased to 180℃ at a rate of 10℃ / min. The purity of styrene oxide was calculated. S5.2: Separation operation to separate the organic phase and the aqueous phase, the organic phase is styrene oxide; S5.3: The separated water phase is subjected to reduced pressure distillation until the volume of the water phase is one third of the original volume to obtain recycled water, which is mixed with deionized water and used in step S1 to complete the recycling of the water phase.

6. A method for oxidizing styrene to produce styrene oxide according to claim 5, characterized in that: The heating rate in step S1.4 is 5°C / min.

7. A method for oxidizing styrene to styrene oxide according to claim 6, characterized in that: The stirring speed in step S1.5 is 500-600 r / min.

8. A method for oxidizing styrene to produce styrene oxide according to claim 7, characterized in that: In step S1.1, the auxiliary agent is one of sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium bicarbonate, and ammonium bicarbonate.

9. A method for oxidizing styrene to produce styrene oxide according to claim 8, characterized in that: The grinding speed in step S4.1 is 800-1000 r / min.

10. A method for oxidizing styrene to styrene oxide according to claim 9, characterized in that: The drying condition in step S4.2 is 60° C. for 40 min.

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