Process for the preparation of silane coupling agents and the catalyst-loaded tubular reactor used

Abstract

This invention relates to the field of silane coupling agent synthesis technology, specifically to a catalyst and apparatus for preparing silane coupling agents via hydrosilylation reactions. The invention discloses a method for preparing a Pt / CN supported catalyst in a tubular reactor, comprising sequentially preparing a nitrogen-doped carbon support, loading and reducing an active metal. The invention also provides a method for preparing a silane coupling agent, utilizing a tubular reactor prepared as described above; a mixture of hydrogen-containing silane and unsaturated hydrocarbon is pumped into a channel; and a hydrosilylation reaction is carried out at a temperature of 20°C to 100°C and at atmospheric pressure to synthesize a silane coupling agent, thereby obtaining a crude silane coupling agent product.

Description

Technical Field

[0001] This invention relates to the field of silane coupling agent synthesis technology, specifically to a catalyst and apparatus for preparing silane coupling agents by hydrosilylation reaction. Background Technology

[0002] Coupling agents are chemical products with special functions, generally possessing two or more functional groups with different properties or functions, thus enabling the combination of inorganic and organic substances. The main types of coupling agents include silane coupling agents, titanate coupling agents, aluminate coupling agents, bimetallic coupling agents, phosphate ester coupling agents, borate ester coupling agents, complexes, and coupling agents of other higher fatty acids, alcohols, and esters. Among these, silane coupling agents are one of the most diverse, in-demand, and commonly used coupling agents. Silane coupling agents are further classified according to the type of functional groups, mainly into sulfur-containing silane coupling agents, aminosilane coupling agents, vinylsilane coupling agents, epoxy-based silane coupling agents, and methacryloxy-based silane coupling agents. The applications and functions of silane coupling agents mainly include three aspects. First, as a surface treatment agent for glass fibers, they can significantly improve the various properties of glass fiber reinforced composites. Secondly, it enhances the performance of inorganic fillers in plastics. By surface-treating inorganic fillers or directly adding them to resins, their dispersibility and adhesion in the resin are improved, thus enhancing performance. Thirdly, it serves as a sealant and adhesive, improving bonding performance and solving long-standing problems of material adhesion failure. Other applications include surface modification of nanoparticles, anti-corrosion surface treatment of metals, and use as a tackifier.

[0003] Currently, the main methods for synthesizing silane coupling agents include Grignard reagent method, direct synthesis method, hydrosilylation method, dehydroxylation of haloalkanes, and alcoholysis method. Among them, hydrosilylation reaction is one of the most important and common chemical reaction types for constructing silicon-carbon bonds in the organosilicon industry. At present, there are a wide variety of catalysts used for this reaction, with the most commonly used being the noble metal platinum catalyst. However, most catalysts have problems such as difficulty in separation, easy loss of platinum, and serious environmental pollution. The more classic catalysts include Speier catalyst (J.Am.Chem.Soc.,1957,79(4):574) and Karstedt catalyst (US3775452), which dominate the industry, but the addition product selectivity is low, there are many side reactions, and they are easy to lose activity. Other hydrosilylation catalysts also have obvious defects in the preparation process. For example, the use of toxic solvents (CN101322946A), difficulties in catalyst separation (CN104817700A), harsh preparation conditions, complex preparation processes (CN106831850A, CN105797775A), and high costs (CN102302951A) are all problems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a hydrosilylation reaction catalyst with high catalytic efficiency, easy in-situ preparation and regeneration based on plasma treatment method, and to realize the efficient and continuous preparation of silane coupling agents.

[0005] To address the aforementioned technical problems, this invention provides a method for directly synthesizing nitrogen-doped carbon material supports based on plasma, and further preparing Pt / CN supported catalysts based on plasma, and applying this method to pipelined continuous hydrosilylation reactions to prepare silane coupling agents.

[0006] This invention provides a method for preparing a Pt / CN supported catalyst in a tubular reactor, comprising sequentially preparing a nitrogen-doped carbon support, loading and reducing an active metal.

[0007] An improvement to the method of preparing Pt / CN supported catalyst in a tubular reactor according to the present invention:

[0008] The device includes an outer stainless steel tube and an inner stainless steel rod; a quartz tube is installed inside the inner cavity of the stainless steel tube, and a stainless steel rod is installed inside the inner cavity of the quartz tube, with the axis of the stainless steel tube, the quartz tube and the stainless steel rod coinciding; the length of the quartz tube is shorter than (slightly shorter than) the length of the stainless steel rod, and both ends of the quartz tube are located outside the inner cavity of the stainless steel tube.

[0009] The inner wall (the entire inner wall) of the stainless steel pipe is lined with stainless steel mesh;

[0010] The stainless steel mesh maintains a certain distance from the outer wall of the quartz tube, which is 1.5mm to 11mm. Therefore, the stainless steel mesh and the outer wall of the quartz tube form a channel, which is the discharge area. Filler is placed in the channel. A raw material inlet and a product outlet are respectively set at both ends of the channel.

[0011] The method involves performing the following steps in sequence:

[0012] 1) Preparation of nitrogen-doped carbon supports:

[0013] 1.1): Continuously introduce the mixed gas into the channel (the introduction time is generally about 15±5 min) until all the air in the channel is expelled;

[0014] The mixed raw material gas is any one of the following:

[0015] It is composed of methane and nitrogen gas mixed at a mass flow rate ratio of 2 to 4:1;

[0016] It is made by mixing methane and ammonia at a mass flow rate ratio of 2 to 4:1;

[0017] It is composed of methylamine and nitrogen gas mixed at a mass flow rate ratio of 2 to 4:1;

[0018] It is made by mixing methylamine and ammonia at a mass flow rate ratio of 2 to 4:1;

[0019] 1.2): Continue to introduce the mixed gas into the channel, and the gas discharged from the product outlet is returned to the channel (re-introduced into the channel through the raw material inlet);

[0020] Furthermore, by adjusting the input power of the plasma high-voltage power supply and simultaneously adjusting its output frequency, microfilament discharge is generated in the discharge region (channel), thereby exciting the plasma. The peak-to-peak output voltage of the plasma high-voltage power supply is 20kV-60kV (preferably 35-60kV), the output frequency is 5kHz-30kHz, and the discharge time is 60min-180min. After the discharge is completed, nitrogen-doped carbon carriers are deposited on the inner wall of the stainless steel tube (corresponding to the pores of the stainless steel mesh), the outer wall of the stainless steel mesh and the quartz tube, and the filling material.

[0021] Note: After the discharge time is reached, turn off the plasma high-voltage power supply and stop the return of the gas discharged from the product outlet into the channel; then switch to introducing an inert gas (such as nitrogen) into the channel for about 15±5 minutes to remove the gas remaining in the channel after the discharge.

[0022] 2) Loading and reduction of active metals

[0023] 2.1): Platinum impregnation:

[0024] A platinum-containing catalyst precursor aqueous solution with a concentration of 0.05M to 1M (preferably 0.1 to 0.3M) is pumped into the channel (i.e., the discharge area) from the feed inlet for 2 to 3 hours.

[0025] Once the pumping time has elapsed, stop pumping the platinum-containing catalyst precursor aqueous solution into the channel and instead introduce an inert gas (such as nitrogen) to blow out the remaining platinum-containing catalyst precursor aqueous solution from the channel.

[0026] 2.2): Platinum loading

[0027] The stainless steel tube was heated and dried at 120–180°C for 2–3 hours, while simultaneously purging it with an inert gas (e.g., nitrogen) to remove water adsorbed on the support (a carbon support with nitrogen doping deposited) in the channel; then heating was stopped and the tube was cooled to room temperature and allowed to stand for 48 ± 12 hours.

[0028] Note: A heating jacket can be used to heat the stainless steel tube;

[0029] 2.3): The mixed gas is introduced into the channel (i.e., into the discharge gap, and the continuous introduction time is about 15±5 min) until the inert gas (e.g., nitrogen) in the channel (10) is discharged.

[0030] The second mixed raw material gas is any one of the following:

[0031] Argon and ammonia are mixed at a mass flow rate ratio of 3 to 19:1 (preferably 9:1);

[0032] Argon and hydrogen are mixed at a mass flow rate ratio of 3 to 19:1.

[0033] Nitrogen and hydrogen are mixed at a mass flow rate ratio of 3 to 19:1.

[0034] 2.4): Continue to introduce mixed gas 2 into channel (10),

[0035] Furthermore, by adjusting the input power of the plasma high-voltage power supply and simultaneously adjusting its output frequency, microfilament discharge is generated in the discharge region to excite the plasma; the peak-to-peak output voltage of the plasma high-voltage power supply is 10kV-40kV, the output frequency is 5kHz-30kHz, and the discharge time is 60min-180min.

[0036] After the discharge time is reached, the plasma high-voltage power supply is turned off, the flow of mixed gas II into the channel is stopped, and then an inert gas (e.g., nitrogen) is introduced into the channel for a period of about 15 ± 5 minutes to remove the remaining gas in the channel and provide inert gas (e.g., nitrogen) protection for the next step of the reaction.

[0037] After the discharge, the nitrogen-doped carbon support formed a Pt / CN supported catalyst;

[0038] That is, the inner wall of the stainless steel tube (corresponding to the pores of the stainless steel mesh), the stainless steel mesh, the outer wall of the quartz tube, and the filling material are all coated with Pt / CN supported catalyst, and the channel is a tubular reactor containing the prepared Pt / CN supported catalyst.

[0039] As a further improvement to the method of preparing Pt / CN supported catalyst in a tubular reactor according to the present invention, the platinum-containing catalyst precursor is chloroplatinic acid.

[0040] As a further improvement to the method of preparing Pt / CN supported catalyst in a tubular reactor according to the present invention, the packing material is quartz wool or quartz sand, with the quartz sand having a mesh size of 20-40 mesh. The function of the packing material is to improve the discharge effect while reducing solid blowout.

[0041] As a further improvement to the method of preparing Pt / CN supported catalyst in a tubular reactor according to the present invention: the stainless steel tube is 100mm to 900mm long and has an inner diameter of 12mm to 25mm.

[0042] For example, when the stainless steel pipe is 800mm long and has an inner diameter of 12mm, and the distance between the stainless steel mesh and the outer wall of the quartz tube is 4mm:

[0043] In step 1.2):

[0044] The total flow rate of the mixed gas is 50 mL / min to 500 mL / min (e.g., 100 mL / min);

[0045] In step 2.1):

[0046] The flow rate of the platinum-containing catalyst precursor aqueous solution is 0.5 mL / min to 3 mL / min (e.g., 1 mL / min);

[0047] In step 2.4):

[0048] The total flow rate of the mixed gas is 50 mL / min to 500 mL / min (for example, 100 mL / min).

[0049] As a further improvement to the method of preparing Pt / CN supported catalyst in a tubular reactor according to the present invention: the length of the quartz tube is 50mm-1000mm and the wall thickness is 1mm-3mm.

[0050] The stainless steel rod is 50mm-1000mm long and 1mm-3mm in diameter, and is made of 022Cr17Ni12Mo2 stainless steel; the stainless steel rod is used as a grounding electrode.

[0051] The stainless steel pipe is made of 022Cr17Ni12Mo2 stainless steel.

[0052] The stainless steel mesh is available in sizes of 100 mesh / inch to 160 mesh / inch and is made of 022Cr17Ni12Mo2 stainless steel. The stainless steel mesh is the same length as the stainless steel pipe and completely covers the inner surface of the stainless steel pipe.

[0053] Stainless steel tubes and stainless steel mesh are used together as high-voltage electrodes.

[0054] Therefore, the length of the channel, i.e. the discharge area, is the same as the length of the stainless steel tube.

[0055] As a further improvement to the method of preparing Pt / CN supported catalyst in a tubular reactor according to the present invention:

[0056] During the plasma reaction in steps 1.2) and 2.4), the stainless steel tube is cooled to control its temperature to ≤60℃ (thus avoiding excessively high reactor temperature).

[0057] Cooling can be achieved by using a cooling water jacket or a fan on the outside of the stainless steel pipe.

[0058] This invention also provides a method for preparing a silane coupling agent, using a tubular reactor prepared by the above method; comprising the following steps:

[0059] Hydrogen-containing silanes and unsaturated hydrocarbons are mixed in a volume ratio of 1:1 to 3, and the resulting mixed raw material is pumped into a channel (i.e., the interstitial channel of the plasma reactor); a hydrosilylation reaction is carried out at a temperature of 20℃ to 100℃ (e.g., 70 to 80℃) and at atmospheric pressure to synthesize silane coupling agents, and crude silane coupling agent products are obtained.

[0060] The residence time of the mixed raw materials in the channel is 3.5 to 4.5 hours.

[0061] The crude silane coupling agent is further purified by conventional distillation to obtain the pure silane coupling agent.

[0062] An improvement to the preparation method of the silane coupling agent of the present invention:

[0063] After the hydrosilylation reaction is completed, an organic solvent is pumped into the channel to clean the channel with the organic solvent. Then, an inert gas (such as nitrogen) is used to purge and heat-dry (drying at 120±10℃ for 150±20 minutes. The purpose of this heat-drying is to remove the residual organic solvent in the reactor).

[0064] After cooling to room temperature, repeat steps 2.3) and 2.4) to regenerate the catalyst.

[0065] As a further improvement to the preparation method of the silane coupling agent of the present invention:

[0066] The hydrogen-containing silane is trimethoxysilane, triethoxysilane, trichlorosilane, or tris(trimethylsiloxy)silane;

[0067] The unsaturated hydrocarbon is an olefin or an olefin derivative, wherein the olefin is octene, and the olefin derivative is acrylamine, allyl methacrylate, allyl mercaptan, or cyclohexanediol.

[0068] The apparatus of this invention employs a coaxial tubular dielectric barrier discharge plasma reactor as the reaction device for plasma synthesis of nitrogen-doped carbon materials and supported catalysts. The channel is formed by a coaxially arranged inner stainless steel rod and an outer stainless steel tube, fitted together with a certain gap, using quartz as the dielectric material. A high-voltage plasma power supply provides high-voltage alternating current with adjustable frequency and peak voltage. The inner stainless steel rod serves as the grounding electrode, and the quartz tube is inserted into the gap between the stainless steel rod and the stainless steel tube, fitting snugly around the inner stainless steel rod. The gap between the outer stainless steel tube and the inner quartz tube forms the channel (i.e., the discharge region). A single layer of stainless steel mesh is tightly welded to the inner wall of the outer stainless steel tube, serving as the high-voltage electrode. Both ends of the apparatus are equipped with PTFE sealing and insulating fasteners with sealing rings to fix and insulate the components, ensuring the airtightness of the apparatus.

[0069] The beneficial effects of this invention are:

[0070] 1. A method for preparing nitrogen-doped carbon material supports using direct plasma processing with mixed gases (including methane / methylamine and nitrogen / ammonia) has been developed, which can achieve in-situ loading of active metals.

[0071] 2. Ammonia plasma is used to facilitate the reduction and regeneration of the catalyst. That is, the catalyst is prepared, supported, reduced, and regenerated in situ within a tubular reactor, and the reaction is completed.

[0072] 3. The proposed reaction apparatus can integrate the functions of carrier preparation, metal loading and reduction, and pipelined continuous hydrosilylation to produce silane coupling agents, thereby improving production efficiency.

[0073] In summary, a reaction system was developed for the in-situ preparation of platinum catalysts supported on nitrogen-doped carbon materials based on plasma, and for the preparation of silane coupling agents through a pipelined continuous hydrosilylation reaction. Attached Figure Description

[0074] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.

[0075] Figure 1 This is a schematic diagram of the plasma reactor device used in this invention.

[0076] Figure 1 In the diagram: 1 is a stainless steel rod, 2 is a quartz tube, 3 is a stainless steel tube, 4 is a stainless steel mesh, 5 is a filler, 6 is a sealing and insulating fastener, 7 is a high-voltage conductor, 8 is a raw material inlet (gas or liquid raw material inlet), 9 is a product outlet, and 10 is a channel. Detailed Implementation

[0077] The present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto:

[0078] Example 1: A plasma reactor apparatus, specifically a reaction device employing a coaxial tube dielectric barrier discharge plasma reactor for the plasma synthesis of nitrogen-doped carbon materials and supported catalysts; the specific structure is as follows:

[0079] A quartz tube 2 is installed inside the inner cavity of a stainless steel tube 3, and a stainless steel rod 1 is installed inside the inner cavity of a quartz tube 2. The center lines of the stainless steel tube 3, the quartz tube 2, and the stainless steel rod 1 coincide. The length of the quartz tube 2 is slightly shorter than the length of the stainless steel rod 1, which facilitates the connection of wires to ground the stainless steel rod 1. Both ends of the quartz tube 2 are located outside the inner cavity of the stainless steel tube 3.

[0080] A stainless steel mesh 4 is installed on the inner wall of the stainless steel tube 3. The stainless steel mesh 4 is a single layer of stainless steel mesh tightly welded to the entire inner wall of the stainless steel tube 3, that is, it completely covers the inner surface of the stainless steel tube 3; therefore, the length of the stainless steel mesh 4 is equal to the length of the stainless steel tube 3. The function of the stainless steel mesh 4 is to enhance microfilament discharge and promote solid deposition.

[0081] The stainless steel mesh 4 maintains a certain distance from the outer wall of the quartz tube 2, which is 1.5mm to 11mm. That is, the stainless steel mesh 4 and the outer wall of the quartz tube 2 form a channel 10, and the filler 5 is placed in this channel 10. The function of the filler 5 is to improve the discharge effect and reduce solid blowout. The filler 5 can be, for example, quartz wool or quartz sand, with the quartz sand having a mesh size of 20-40 mesh.

[0082] The inner wall of the quartz tube 2 should be as close as possible to the outer surface of the stainless steel rod 1, i.e., the distance between the two should be ≤0.05mm.

[0083] Sealing and insulating fasteners 6 are respectively installed at both ends of the stainless steel tube 3. The sealing and insulating fasteners 6 are used to seal the stainless steel tube 3 and the quartz tube 2. The sealing and insulating fasteners 6 are polytetrafluoroethylene sealing and insulating fasteners with sealing rings, which fix and insulate the various components (including the stainless steel tube 3, the quartz tube 2 and the stainless steel rod 1) from each other, and ensure the airtightness of the device.

[0084] A raw material inlet 8 (for gaseous or liquid raw materials) is provided at one end of channel 10, and a product outlet 9 is provided at the other end of channel 10. A high-voltage conductor 7 is connected to a stainless steel pipe 3. A heating jacket and a cooling circulating water jacket are provided on the outer surface of the stainless steel pipe 3.

[0085] In actual use:

[0086] Stainless steel tube 3 and stainless steel mesh 4 together serve as high-voltage electrodes, stainless steel rod 1 serves as grounding electrode, and quartz tube 2 serves as dielectric material. A plasma high-voltage power supply provides high-voltage alternating current with adjustable frequency and peak voltage.

[0087] Specifically:

[0088] The wall thickness of quartz tube 2 is 1mm-3mm.

[0089] Stainless steel bars, 50mm-1000mm in length, 1mm-3mm in diameter, made of 022Cr17Ni12Mo2 stainless steel.

[0090] Stainless steel pipes are available in lengths of 100mm-900mm and inner diameters of 12mm-25mm. The material is 022Cr17Ni12Mo2 stainless steel.

[0091] The length of the quartz tube 2 is slightly shorter than the length of the stainless steel rod 1, that is, about 10 to 20 mm of each end of the stainless steel rod 1 protrudes outside the quartz tube 2, which facilitates the connection of wires to ground the stainless steel rod 1.

[0092] The stainless steel mesh 4 has a specification of 100 mesh / inch-160 mesh / inch and is made of 022Cr17Ni12Mo2 stainless steel.

[0093] The plasma high-voltage power supply can generate stable alternating current with a peak voltage of 0-60kV and a frequency of 1kHz-50kHz. The discharge gap (the distance between the stainless steel mesh 4 and the outer wall of the quartz tube 2) is 1.5mm-11mm, that is, the width of the channel 10 is 1.5mm-11mm, and the length of the discharge area is equal to the length of the stainless steel tube 3, which is 100mm-900mm. The channel 10 is filled with quartz wool or quartz sand to improve the discharge effect and reduce the blowout of the generated solids (i.e., the synthesis of nitrogen-doped carbon support and Pt / CN supported catalyst).

[0094] Example 1-1:

[0095] Stainless steel pipe 3 is 800mm long and 12mm in inner diameter, and stainless steel mesh 4 has a wall thickness of 0.1mm.

[0096] The outer diameter of quartz tube 2 is 7.9 mm, and the length of quartz tube 2 is 900 mm;

[0097] Therefore, the inner ring diameter of channel 10 is 7.9 mm, the outer ring diameter is 11.9 mm, and the length is 800 mm; that is, the distance between the stainless steel mesh 4 and the quartz tube 2 is 4 mm.

[0098] Perform the following steps in sequence:

[0099] I. Catalyst Preparation:

[0100] 1) Preparation of nitrogen-doped carbon supports:

[0101] 1.1) Methane and nitrogen are mixed uniformly at a mass flow rate ratio of 4:1 and then introduced into channel 10 through raw material inlet 8 for 15 minutes to exhaust all the air in channel 10.

[0102] 1.2) Then, the mixed gas 1 is continued to be introduced into channel 10 through raw material inlet 8, with a total flow rate of 100 mL / min. Simultaneously, the input power and output frequency of the plasma high-voltage power supply are adjusted to generate microfilament discharge in the discharge gap (i.e., the discharge region, channel 10) between stainless steel tube 3 and quartz tube 2, exciting a plasma of methane and nitrogen, thereby synthesizing nitrogen-doped carbon support. The peak-to-peak output voltage of the plasma high-voltage power supply is 35 kV, the output frequency is 11 kHz, and the discharge time is 120 min. The gas discharged from product outlet 9 is returned to channel 10 (re-introduced into channel 10 through raw material inlet 8).

[0103] After the discharge time is reached, the plasma high-voltage power supply is turned off, and the gas discharged from the product outlet 9 is stopped from being introduced back into channel 10. Then, nitrogen gas is introduced into channel 10 for 15 minutes to remove the gas remaining in channel 10 after the discharge.

[0104] At this time, nitrogen-doped carbon carriers are deposited on the inner wall of stainless steel tube 3 (corresponding to the pores of stainless steel mesh 4), the outer surface of stainless steel mesh 4 and quartz tube 2, and the filler 5.

[0105] Note: During the plasma reaction (i.e., during the discharge process), the outer surface of the stainless steel tube 3 is cooled by a cooling circulating water jacket or a fan to ensure that the temperature of the stainless steel tube 3 is controlled at ≤60℃, so as to avoid the reactor temperature from being too high.

[0106] Finally, the gas discharged from product outlet 9 can be absorbed by alkaline solution and acid solution in sequence and then released. This is a conventional technique and will not be described in detail in this invention.

[0107] II) Loading and Reduction of Active Metals:

[0108] 2.1) Platinum impregnation:

[0109] A 0.1M chloroplatinic acid solution was pumped into the discharge gap, that is, the chloroplatinic acid solution was introduced into the channel 10 through the raw material inlet 8 at a flow rate of 1 mL / min and a pumping time of 2.5 h.

[0110] The purpose of this step is to impregnate the support (nitrogen-doped carbon support) with chloroplatinic acid solution, so that the chloroplatinic acid solution flows slowly in channel 10.

[0111] After the pumping time is reached, stop pumping chloroplatinic acid solution into channel 10 and switch to nitrogen gas to blow out the remaining chloroplatinic acid solution from the channel.

[0112] The chloroplatinic acid solution discharged from product outlet 9 of channel 10 can be reused after the concentration is readjusted.

[0113] 2.2) Platinum loading

[0114] The stainless steel tube 3 was heated in a heating mantle and dried at 150°C for 2.5 hours, while being purged with nitrogen (the purpose of nitrogen purging is to blow out the water adsorbed on the carrier in channel 10). The stainless steel tube 3 was then cooled to room temperature and left to stand for 48 hours.

[0115] 2.3) Argon and ammonia are mixed uniformly at a mass flow rate ratio of 9:1 and then introduced into channel 10 as mixed gas 2. The mixture is continuously introduced for 15 minutes, and then the nitrogen in channel 10 is discharged.

[0116] 2.4) Ammonia plasma reduction of platinum:

[0117] The second mixed gas is continued to be introduced into channel 10 through raw material inlet 8, with a total flow rate of 100 mL / min. The input power and output frequency of the plasma high-voltage power supply are adjusted to generate microfilament discharge in the discharge gap between stainless steel tube 3 and quartz tube 2 (i.e., channel 10), exciting ammonia plasma. The peak-to-peak output voltage of the plasma high-voltage power supply is 30 kV, the output frequency is 12 kHz, and the discharge time is 120 min.

[0118] After the discharge time is reached, the plasma high-voltage power supply is turned off, the flow of mixed gas II into channel 10 is stopped, and nitrogen gas is introduced for 15 minutes to purge the remaining ammonia and other gases in the channel and to provide nitrogen protection for the next reaction step.

[0119] Therefore, after the reaction, the nitrogen-doped carbon support forms a Pt / CN supported catalyst; that is, the inner wall of the stainless steel tube 3 (corresponding to the pores of the stainless steel mesh), the stainless steel mesh 4, the outer surface of the quartz tube 2, and the filler 5 are all coated with the Pt- / CN supported catalyst.

[0120] Thus, the tubular reactor carrying the in-situ prepared Pt / CN supported catalyst is complete. Channel 10 is the tubular reactor containing the prepared Pt / CN supported catalyst.

[0121] Note: During the plasma reaction (i.e., during the discharge process), the outer surface of the stainless steel tube 3 is cooled by a cooling circulating water jacket or a fan to ensure that the temperature of the stainless steel tube 3 is controlled at ≤60℃, so as to avoid the reactor temperature from being too high. two,

[0123] 100 mL each of trimethoxysilane and allyl glycidyl ether were mixed evenly and pumped into a tubular reactor (i.e., through feed inlet 8 into channel 10) loaded with the in-situ prepared Pt / CN supported catalyst. The reaction temperature was maintained at 80 °C using a heating mantle, and the reaction time was 4 h. After the reaction was completed, the product was analyzed by GC-MS, and the yield of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was 89%.

[0124] After Examples 1-2 and 1-1, the apparatus was treated as follows: Ethanol was introduced into channel 10 through raw material inlet 8 to wash the reactor at a flow rate of 20 mL / min for 30 min; the stainless steel tube 3 was dried at 120°C for 2.5 h using a heating mantle, while simultaneously purging with nitrogen (the purpose of nitrogen purging is to remove ethanol from channel 10), and then the stainless steel tube 3 was cooled to room temperature and allowed to stand for 48 h. Steps 2.3) and 2.4) in Example 1 were repeated to regenerate the catalyst.

[0125] Then, the operation was carried out according to step two of Example 1, and the result was that the yield of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was 87%.

[0126] After the blank comparative example and Example 1-1 were completed, the apparatus was not treated in any way after the reaction, and the operation was carried out directly according to step two of Example 1. The result was that the yield of 3-(2,3-epoxypropoxy)propyltrimethoxysilane was 22%.

[0127] A comparison of Examples 1-2 and the blank control shows that plasma treatment between the two reactions, repeating the catalyst metal reduction process to regenerate the catalyst, can greatly improve the product yield.

[0128] Examples 2-5:

[0129] Compared to Example 1-1, the mass flow rate ratio of methane and nitrogen was changed in "I) Preparation of Nitrogen-Doped Carbon Support," while other operations remained the same as in Example 1-1, resulting in Examples 2-5. A comparison of process parameters and reaction results with Examples 1-1 is shown in Table 1.

[0130] Table 1

[0131] Example methane to nitrogen mass flow rate ratio Product yield (%) 1-1 4:1 89 2 2:1 79 3 5:2 82 4 7:2 84 5 3:1 82

[0132] Examples 6-10:

[0133] Compared to Example 1-1, the concentration of chloroplatinic acid solution in "II) Loading and Reduction of Active Metals" was changed, while other operations remained the same as in Example 1-1, resulting in Examples 6-10. A comparison of process parameters and reaction results with Example 1-1 is shown in Table 2.

[0134] Table 2

[0135] Example Chloroplatinic acid solution concentration (M) Product yield (%) 1-1 0.1 89 6 0.2 82 7 0.3 81 8 0.4 79 9 0.5 74 10 0.6 61

[0136] Examples 11-14:

[0137] Compared to Example 1-1, the voltage peak value in "I) Preparation of nitrogen-doped carbon support 1.2)" was changed, while other operations remained the same as in Example 1-1, resulting in Examples 11-14. A comparison of process parameters and reaction results with Example 1-1 is shown in Table 3.

[0138] Table 3

[0139] Example Peak-to-peak voltage (kV) Product yield (%) Example 1-1 35 89 11 20 33 12 30 68 13 50 88 14 60 91

[0140] Examples 15-19:

[0141] Compared to Example 1-1, the reaction temperature in "Step Two" was changed, while other operations remained the same as in Example 1-1, resulting in Examples 15-19. A comparison of process parameters and reaction results with Example 1-1 is shown in Table 4.

[0142] Table 4

[0143]

[0144]

[0145] Example 20

[0146] Compared to Example 1-1, the reactants and reaction temperature in step two were changed, while the reaction time remained essentially unchanged; other operations were the same as in Example 1-1, resulting in the Example 20 series. A comparison of process parameters and reaction results with Example 1-1 is shown in Table 5.

[0147] Table 5

[0148]

[0149]

[0150] Comparative Example 1: In step 1.1) of Example 1-1, the "methane to nitrogen mass flow rate ratio 4:1" was changed to "methylamine to ammonia mass flow rate ratio 4:1", and the rest was the same as in Example 1-1.

[0151] The results are shown in Table 6 below.

[0152] Comparative Example 2-1: The ratio of argon to ammonia flow rate in the mixed gas mixture of Example 1-1 was changed from 9:1 to 4:1, while the rest remained essentially the same as in Example 1-1.

[0153] The results are shown in Table 6 below.

[0154] Comparative Example 2-2: The ratio of argon to ammonia flow rate in the mixed gas mixture of Example 1-1 was changed from 9:1 to 19:1, while the rest remained essentially the same as in Example 1-1.

[0155] The results are shown in Table 6 below.

[0156] Comparative Example 3-1: The mixed gas 2 in Example 1-1 was replaced with argon and hydrogen, with a mass flow rate ratio of argon to hydrogen of 9:1, and the rest was the same as in Example 1-1.

[0157] The results are shown in Table 6 below.

[0158] Comparative Example 3-2: The mixed gas 2 of Example 1-1 was replaced with nitrogen and hydrogen, with a nitrogen to hydrogen mass flow rate ratio of 9:1, and the rest was the same as in Example 1-1.

[0159] The results are shown in Table 6 below.

[0160] Table 6

[0161] Comparative Example Product yield (%) Comparative Example 1 81 Comparative Example 2-1 79 Comparative Example 2-2 75 Comparative Example 3-1 85 Comparative Example 3-2 70

[0162] Finally, it should be noted that the above examples are merely some specific embodiments of the present invention. Obviously, the present invention is not limited to the above embodiments and many variations are possible. All variations that can be directly derived or conceived by those skilled in the art from the disclosure of the present invention should be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a Pt / CN supported catalyst in a tubular reactor, characterized in that: The tubular reactor includes a stainless steel tube (3) on the outer layer and a stainless steel rod (1) on the inner layer; a quartz tube (2) is installed in the inner cavity of the stainless steel tube (3), and a stainless steel rod (1) is installed in the inner cavity of the quartz tube (2); the center lines of the stainless steel tube (3), the quartz tube (2) and the stainless steel rod (1) coincide; the length of the quartz tube (2) is shorter than the length of the stainless steel rod (1), and both ends of the quartz tube (2) are located outside the inner cavity of the stainless steel tube (3); The inner wall of the stainless steel pipe (3) is provided with a stainless steel mesh (4); The stainless steel mesh (4) and the outer wall of the quartz tube (2) maintain a certain distance, which is 1.5mm~11mm. Therefore, the stainless steel mesh (4) and the outer wall of the quartz tube (2) form a channel (10), which is a discharge area. A filler (5) is set in the channel (10). A raw material inlet (8) and a product outlet (9) are set at both ends of the channel (10). The method involves performing the following steps in sequence: 1) Preparation of nitrogen-doped carbon supports: 1.1): The mixed raw material gas is continuously introduced into the channel (10) until all the air in the channel (10) is discharged; The mixed raw material gas is any one of the following: It is composed of methane and nitrogen gas mixed at a mass flow rate ratio of 2 to 4:1; It is made by mixing methane and ammonia at a mass flow rate ratio of 2 to 4:1; It is composed of methylamine and nitrogen gas mixed at a mass flow rate ratio of 2 to 4:1; It is made by mixing methylamine and ammonia at a mass flow rate ratio of 2 to 4:1; 1.2): Continue to pass the mixed raw material gas into the channel (10), and the gas discharged from the product outlet (9) is returned to the channel (10); Furthermore, by adjusting the input power of the plasma high-voltage power supply and simultaneously adjusting the output frequency of the plasma high-voltage power supply, microfilament discharge is generated in the discharge region to excite the plasma; the peak-to-peak output voltage of the plasma high-voltage power supply is 20kV-60kV, the output frequency is 5kHz-30kHz, and the discharge time is 60min-180min; after the discharge is completed, nitrogen-doped carbon carriers are deposited on the inner wall of the stainless steel tube (3), the stainless steel mesh (4), the outer wall of the quartz tube (2), and the filling material (5). 2) Loading and reduction of active metals 2.1): Platinum impregnation: A platinum-containing catalyst precursor aqueous solution with a concentration of 0.05M~1M is pumped into channel (10) from the raw material inlet (8) for 2h~3h. After the pumping time is reached, stop pumping the platinum-containing catalyst precursor aqueous solution into the channel (10) and introduce inert gas to blow out the remaining platinum-containing catalyst precursor aqueous solution from the channel. 2.2): Platinum loading The stainless steel tube (3) is dried at 120~180℃ for 2~3h, and at the same time, it is purged with inert gas to purge the water adsorbed on the carrier in the channel (10); then heating is stopped and the tube is cooled to room temperature and left to stand for 48±12h. 2.3): The mixed raw material gas is introduced into the channel (10) until the inert gas in the channel (10) is discharged; The second mixed raw material gas is any one of the following: Argon and ammonia are mixed at a mass flow rate ratio of 3 to 19:

1. Argon and hydrogen are mixed at a mass flow rate ratio of 3 to 19:

1. Nitrogen and hydrogen are mixed at a mass flow rate ratio of 3 to 19:

1. 2.4): Continue to introduce mixed raw material gas 2 into channel (10), Furthermore, by adjusting the input power of the plasma high-voltage power supply and simultaneously adjusting its output frequency, microfilament discharge is generated in the discharge region to excite the plasma. The peak-to-peak output voltage of the plasma high-voltage power supply is 10kV-40kV, the output frequency is 5kHz-30kHz, and the discharge time is 60min-180min. After the discharge, the nitrogen-doped carbon support forms a Pt / CN supported catalyst. Channel (10) is a tubular reactor for the prepared Pt / CN supported catalyst.

2. The method for preparing a Pt / CN supported catalyst in a tubular reactor according to claim 1, characterized in that: The precursor for the platinum-containing catalyst is chloroplatinic acid.

3. The method for preparing a Pt / CN supported catalyst in a tubular reactor according to claim 2, characterized in that: The filler (5) is quartz wool or quartz sand, and the quartz sand is 20-40 mesh.

4. The method for preparing a Pt / CN supported catalyst in a tubular reactor according to any one of claims 1 to 3, characterized in that: Stainless steel pipe (3) Length 100mm~900mm, inner diameter 12mm~25mm; In step 1.2): The total flow rate of the mixed feed gas is 50 mL / min - 500 mL / min. In step 2.1): The flow rate of the platinum-containing catalyst precursor aqueous solution was 0.5 mL / min to 3 mL / min; In step 2.4): The total flow rate of the mixed raw material gas is 50 mL / min to 500 mL / min.

5. The method for preparing a Pt / CN supported catalyst in a tubular reactor according to claim 4, characterized in that: The quartz tube (2) has a tube length of 50mm-1000mm and a tube wall thickness of 1mm-3mm; Stainless steel rod (1) is 50mm-1000mm long and 1mm-3mm in diameter. Stainless steel rod (1) is used as a grounding electrode. The stainless steel mesh (4) has a specification of 100 mesh / inch to 160 mesh / inch. The stainless steel mesh (4) has the same length as the stainless steel pipe (3) and completely covers the inner surface of the stainless steel pipe (3). Stainless steel tube (3) and stainless steel mesh (4) are used together as high-voltage electrodes.

6. The method for preparing a Pt / CN supported catalyst in a tubular reactor according to claim 5, characterized in that: During the plasma reaction process in steps 1.2) and 2.4), the stainless steel tube (3) is cooled to control the temperature of the stainless steel tube (3) to ≤60℃.

7. A method for preparing a silane coupling agent, characterized in that: Using the tubular reactor employed in any one of claims 1 to 6, the method includes the following steps: The method for preparing a Pt / CN supported catalyst in a tubular reactor as described in any one of claims 1 to 6; Then, the hydrogen-containing silane and unsaturated hydrocarbon are mixed in a volume ratio of 1:1~3, and the resulting mixed raw material is pumped into channel (10); a hydrosilylation reaction is carried out at a temperature of 20℃~100℃ and a normal pressure to synthesize a silane coupling agent, and a crude silane coupling agent product is obtained. The residence time of the mixed raw materials in the channel (10) is 3.5~4.5h.

8. The method for preparing the silane coupling agent according to claim 7, characterized in that: After the hydrosilylation reaction is completed, an organic solvent is pumped into the channel (10) to clean the channel (10) with the organic solvent, and then the channel is purged with an inert gas and heated to dry. After cooling to room temperature, repeat steps 2.3) and 2.4) to regenerate the catalyst.

9. The method for preparing the silane coupling agent according to claim 8, characterized in that: The hydrogen-containing silane is trimethoxysilane, triethoxysilane, trichlorosilane, or tris(trimethylsiloxy)silane; The unsaturated hydrocarbon is an olefin or an olefin derivative, wherein the olefin is octene, and the olefin derivative is acrylamine, allyl methacrylate, allyl mercaptan, or cyclohexanediol.

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