Novel membrane reactor for preparing methanol through CO2 hydrogenation catalytic conversion

Abstract

The invention relates to a membrane reactor for preparing methanol through hydrogenation catalytic conversion of CO2, which is characterized in that a Cu-ZnO-A1203-ZrO2 catalyst layer and an organic-inorganic hybrid SiO2 membrane are established in a unified system through an internal structure design, and the most reasonable distribution of the geometric structure of the reactor, the catalyst and the membrane is realized. Under the environment that the working temperature is 200-450 DEG C and the working pressure is 2-5 MPa, a special permeable membrane, namely an organic-inorganic hybrid SiO2 membrane, is creatively utilized to synchronously remove water vapor as a reaction byproduct in situ, so as to promote forward proceeding of the reaction. Meanwhile, the catalyst Cu-ZnO-A1203-ZrO2 can be effectively protected by the structure of the reactor, and the poisoning and inactivation probability of the catalyst is reduced. When the reactor disclosed by the invention is used in a specific experiment for preparing methanol by catalytic hydrogenation of CO2, namely under the conditions of 300 DEG C, 3 MPa and W / F of 10 hours, the conversion rate of CO2 is up to 27.64%, and the yield of methanol is 26.50%, which are respectively improved by 7.3 times and 7.1 times compared with the traditional fixed bed reactor.

Description

Technical Field

[0001] The invention belongs to the field of chemical equipment and relates to catalytic conversion membrane reactor technology, in particular to a novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation. Background Art

[0002] Membrane catalytic reactor is a new catalytic reaction technology developed in recent years, with many advantages such as simple process, low investment cost and low energy consumption. The production of methanol by hydrogenation of C02 is a reversible equilibrium reaction. Due to the limitations of the reaction thermodynamic equilibrium, as well as the existence of competitive reverse water-gas shift reaction and by-product water-induced catalyst deactivation. In traditional fixed-bed reactors, the C02 conversion rate and methanol selectivity are usually relatively low, and traditional reactors can only realize the reaction process, and cannot effectively improve the reaction efficiency and C02 conversion rate. Therefore, the development of new reaction technology is very necessary to improve the C02 conversion rate and methanol selectivity. Summary of the invention

[0003] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a novel membrane reactor for catalytic conversion of CO2 to methanol. For the CO2 hydrogenation to methanol reaction, the membrane catalytic reactor integrates a Cu-ZnO-A1203-ZrO2 catalyst layer and an organic-inorganic hybrid SiO2 membrane, which efficiently realizes the coupling of reaction and separation processes, is beneficial to overcome the thermodynamic equilibrium limitations of the reaction, efficiently promotes the reaction towards the direction of methanol production, and improves the CO2 conversion rate.

[0004] The present invention solves the technical problem by adopting the following technical solutions:

[0005] A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation comprises a membrane reaction chamber body, a Cu-ZnO-A1203-ZrO2 catalyst layer is coaxially arranged inside the reaction chamber body, and an organic-inorganic hybrid SiO2 membrane (15) is coaxially arranged inside the Cu-ZnO-A1203-ZrO2 catalyst layer. The Cu-ZnO-A1203-ZrO2 catalyst layer and the organic-inorganic hybrid SiO2 membrane are effectively integrated.

[0006] Furthermore, an inert carrying gas inlet is connected to the top of the reaction chamber body, an inert carrying gas outlet is connected to the bottom of the reaction chamber body, an air inlet pipe and an air outlet pipe are arranged from top to bottom at 40 mm and 95 mm from the top of the reaction chamber body on one side of the reaction chamber body, and the length of the air inlet pipe and the air outlet pipe is 95 mm, and a catalyst feed port is arranged at 48 mm from the top of the reaction chamber body on the other side of the reaction chamber body in communication with the Cu-ZnO-A1203-ZrO2 catalyst layer. The above structural setting and position parameters can maximize the use of the organic-inorganic hybrid SiO2 membrane.

[0007] When manufacturing the reactor of the present patent application, aluminum isopropoxide sol is uniformly coated on a commercial α-Al2O3 tube with a pore size of 100 nm by an immersion-pulling method, and the immersion time is 3 seconds to prepare a defect-free α-Al2O3 / γ-Al2O3 support; then, a BTESE sol coating liquid is uniformly coated on the α-Al2O3 / γ-Al2O3 support by an immersion-pulling method, and the immersion time is 15 seconds to prepare a BTESE membrane tube with a defect-free three-layer asymmetric structure, namely the organic-inorganic hybrid SiO2 membrane (15); then, a Cu-based catalyst Cu-ZnO-A1203-ZrO2 catalyst is filled outside the membrane tube to form a Cu-ZnO-A1203-ZrO2 catalyst layer (13), thereby constructing a dual-functional reactor reaction system of an organic-inorganic hybrid SiO2 membrane (15) reactor coupled with a Cu-based catalyst.

[0008] Furthermore, the preparation method of the organic-inorganic hybrid SiO2 film (15) is as follows:

[0009] Step 1: Preparation of α-Al2O3 / γ-Al2O3 support

[0010] The α-Al2O3 / γ-Al2O3 support was prepared by coating the commercial α-Al2O3 tube with a pore size of 100 nm with a uniform aluminum isopropoxide sol by the dip-pulling method, placing it in a humidity incubator for more than 24 hours, and then placing it in a high-temperature sintering furnace for a temperature rise and fall vacant calcination process, and then naturally cooling it to room temperature.

[0011] Step 2: Preparation of BTESE sol

[0012] First, 10 mL of BTESE and anhydrous ethanol were poured into a 50 mL conical flask and mixed evenly by magnetic stirring. Then, the conical flask was taken out and placed in an ice bath. 5 mL of 1 mol·L -1 Nitric acid and 20 mL of anhydrous ethanol were mixed evenly in a beaker. The mixed solution of nitric acid and anhydrous ethanol was added dropwise into the mixed solution of BTESE and anhydrous ethanol using a constant pressure funnel. The stirring speed was 200 r·min. -1， The above solution was then placed in a water bath at 60°C and refluxed for 1.5 h to obtain a BTESE sol having a formula of n(BTESE):n(H2O):n(EtOH):n(H + )=1:22.24:26.12:0.2;

[0013] (3) Preparation of BTESE membrane

[0014] Take the sol and dilute it five times with anhydrous ethanol. The diluted sol is the coating liquid. It is dipped and pulled once on the surface of a homemade α-Al2O3 / γ-Al2O3 support. The membrane tube is placed in a humidity incubator at a temperature of 40°C and a relative humidity of 25% to dry for 3 hours. Then the membrane tube is placed in a tubular furnace and calcined at a calcination temperature of 400°C, a holding time of 3 hours, and a heating / cooling rate of 0.5°C / min.

[0015] Furthermore, the upper part of the organic-inorganic hybrid SiO2 film is fixed to the upper nut of the reactor through an upper lining film sealing ring, and the lower part of the organic-inorganic hybrid SiO2 film is fixed to the lower nut of the reactor through a lower lining film sealing ring.

[0016] Furthermore, a reactor upper gland is coaxially arranged outside the inert carrier gas inlet, and a reactor lower gland is coaxially arranged outside the inert carrier gas outlet, so as to realize the function of fixing and connecting the reaction chamber body 12 and the upper and lower parts of the organic-inorganic hybrid SiO2 film 15 from the outside.

[0017] Further, inside the upper pressure cover of the reactor, the upper nut of the reactor is sealed by the upper nut sealing ring groove and the upper nut sealing ring, and the lower nut of the reactor is sealed by the lower nut sealing ring groove and the lower nut sealing ring.

[0018] Furthermore, a pressure ring 11 is provided coaxially with the organic-inorganic hybrid SiO 2 film 15 at the lower part of the organic-inorganic hybrid SiO 2 film 15 and inside the lower pressure cover 5 of the reactor.

[0019] The advantages and positive effects of the present invention are:

[0020] 1. The reaction of CO2 hydrogenation catalysis to produce methanol needs to be carried out at high temperature and high pressure. If the methanol in the product and the by-product water are to be separated during the reaction, a selective water-permeable membrane with hydrothermal stability is required. The reactor of the present invention selects an organic-inorganic hybrid SiO2 membrane. The lining membrane can effectively separate water and prevent water vapor from deactivating the active center of the catalyst. The organic-inorganic hybrid SiO2 membrane has strong hydrothermal stability at 300°C and can promote the reaction towards the direction of methanol production.

[0021] 2. The outer diameter of the organic-inorganic hybrid SiO2 membrane in the reactor of the present invention is only 12mm and the total length is 145mm. Therefore, how to fix the lining membrane in the stainless steel reactor body and achieve the effect of sealing without leakage under high temperature and high pressure is a difficulty in the design of the invention. The present invention fixes the organic-inorganic hybrid SiO2 membrane in the stainless steel reactor body through the structure of tongue-and-groove connection, sealing ring and threaded connection, and can achieve sealing under the conditions of working temperature of 200-450℃ and working pressure of 2-5MPa. When the pressure of the airtightness test is 6.0MPa, it is maintained for 2 hours with a pressure drop of ≤2%.

[0022] 3. In the prior art, the most common catalyst for the CO2 hydrogenation catalytic methanol production system is the Cu / ZnO-based catalyst, which has a low cost. However, there is a new type of catalyst on the market, namely the Cu-ZnO-A12O3-ZrO2 catalyst, which has a high conversion rate and selectivity, but is expensive and difficult to manufacture. The reactor of the present invention can protect the catalyst during the loading of the catalyst and the reaction process, thereby reducing the probability of the catalyst being poisoned and deactivated.

[0023] 4. Different from the traditional fixed bed catalysis, when the reactor of the present invention is used for reaction, the inert carrying gas used needs to carry the by-product water obtained by the reaction out of the reactor through the internal channel of the organic-inorganic hybrid SiO2 membrane, and the mixed gas of CO2 and H2 needs to fully contact and react with the catalyst Cu-ZnO-A1203-ZrO2 in the channel between the outer wall of the organic-inorganic hybrid SiO2 membrane and the inner wall of the reactor, and the product methanol flows out from the reaction gas outlet. The invention separates the gas path channel by nut bosses and multiple sets of sealing rings without interfering with each other, realizes the simultaneous reaction and separation process, improves the conversion rate and selectivity of the reaction, and increases the single-pass conversion rate of CO2 from 18.9% to more than 20%, and the selectivity of methanol from 67.3% to more than 80%, breaking through the industrial bottleneck of CO2 catalytic hydrogenation to methanol.

[0024] 5. The present invention is scientifically and reasonably designed, and provides a novel membrane reactor for catalytic conversion of CO2 to produce methanol. The Cu-ZnO-A1203-ZrO2 catalyst layer and the organic-inorganic hybrid SiO2 membrane are established in a unified system through the internal structure design, so as to realize the most reasonable distribution of the three elements of the reactor geometry, catalyst and membrane. Under the environment of working temperature of 200-450℃ and working pressure of 2-5MPa, the special water-permeable membrane organic-inorganic hybrid SiO2 membrane is used to synchronously remove the reaction byproduct water vapor in situ, so as to promote the forward reaction. At the same time, the structure of the reactor can effectively protect the probability of poisoning and deactivation of the catalyst Cu-ZnO-A1203-ZrO2. In the specific CO2 catalytic hydrogenation to produce methanol experiment using the reactor of the present invention, that is, under the conditions of 300℃, 3MPa, and W / F=10h, the CO2 conversion rate is as high as 27.64%, and the methanol yield is 26.50%, which are 7.3 times and 7.1 times higher than those of the traditional fixed bed reactor, respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a front cross-sectional view of the membrane reactor of the present invention. DETAILED DESCRIPTION

[0026] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0027] A novel membrane reactor for catalytic conversion of CO2 to methanol, such as Figure 1 As shown, it includes a membrane reactor reaction chamber body 12 made of 316 stainless steel. The reaction chamber body 12 has a total length of 134 mm, an inner diameter of 18 mm, an outer diameter of 28 mm, and a wall thickness of 5 mm. It can withstand high temperature and high pressure. A Cu-ZnO-A1203-ZrO2 catalyst layer 13 is coaxially arranged inside the reaction chamber body 12, and an organic-inorganic hybrid SiO2 membrane 15 is coaxially arranged inside the Cu-ZnO-A1203-ZrO2 catalyst layer 13.

[0028] The top of the reaction chamber body 12 is connected to an inert carrier gas inlet 1 through a reactor upper nut 18, and the bottom of the reaction chamber body 12 is connected to an inert carrier gas outlet 6 through a reactor lower nut 7. The upper part of the organic-inorganic hybrid SiO2 film 15 is fixed to the reactor upper nut 18 through an upper lining film sealing ring 19, and the lower part of the organic-inorganic hybrid SiO2 film 15 is fixed to the reactor lower nut 7 through a lower lining film sealing ring 8.

[0029] A reactor upper gland 2 is coaxially arranged on the outside of the inert carrier gas inlet 1, and a reactor lower gland 5 is coaxially arranged on the outside of the inert carrier gas outlet 6. From the outside, the reaction chamber body 12 and the upper and lower parts of the organic-inorganic hybrid SiO2 film 15 are fixedly connected. Inside the reactor upper gland 2, the reactor upper nut 18 seals the upper part of the reactor through the upper nut sealing ring groove 16 and the upper nut sealing ring 17, and the reactor lower nut 7 seals the lower part of the reactor through the lower nut sealing ring groove 9 and the lower nut sealing ring 10. At the same time, at the lower part of the organic-inorganic hybrid SiO2 film 15, inside the reactor lower gland 5, a pressure ring 11 is coaxially arranged with the organic-inorganic hybrid SiO2 film 15.

[0030] On one side of the reaction chamber body 12, an air inlet pipe 3 and an air outlet pipe 4 are arranged from top to bottom at 40 mm and 95 mm from the top of the reaction chamber body 12, and the length of the air inlet pipe 3 and the air outlet pipe 4 is 95 mm. On the other side of the reaction chamber body 12, a catalyst feed port 14 is arranged at 48 mm from the top of the reaction chamber body 12 and is connected to the Cu-ZnO-A1203-ZrO2 catalyst layer 13. The catalyst feed port 14 is set as a welding head ferrule plug for loading the catalyst required for the reaction. At this position, the organic-inorganic hybrid SiO2 membrane 15 can be used to the maximum extent.

[0031] During specific implementation, a boss with an outer diameter of 18mm, an inner diameter of 13mm and a height of 3mm is arranged on the upper part of the organic-inorganic hybrid SiO2 film 15 of the reactor, which can be used to fix the sealing ring 19 of the organic-inorganic hybrid SiO2 film. The upper nut sealing ring groove 16 and the lower nut sealing ring groove 9 are arranged with an outer diameter of 31mm, an inner diameter of 25mm and a depth of 4mm, which are used to match and fix the upper nut sealing ring 17 and the lower nut sealing ring 10. The upper nut 18 of the reactor and the lower nut 7 of the reactor are both arranged with a M38*1.5mm thread with a length of 28mm, and cooperate with the gland, nut and sealing ring to achieve the effect of sealing under high pressure. The upper nut 18 of the reactor and the lower nut 7 of the reactor are both made of 316 stainless steel, which can withstand high temperature and high pressure, with a total height of 22mm and an inner diameter of 18mm.

[0032] The reactor upper gland 2 and the reactor lower gland 5 are made of 316 stainless steel, which can withstand high temperature and high pressure. The total height is 35 mm, the outer diameter is 44 mm, the internal thread is M38*1.5 mm, and the outside is a hexagonal nut, which is convenient for using a wrench to tighten and seal the upper gland, upper nut and reactor.

[0033] The pressure ring 11 is made of 316 stainless steel, which can withstand high temperature and high pressure. It has a total height of 14mm, an internal diameter of 12.5mm, and an external thread of M18*1mm. It cooperates with the reactor lower nut 7, the reactor lower pressure cover 5, the lower nut sealing ring 10, and the lower lining membrane sealing ring 8 to fix and seal the organic-inorganic hybrid SiO2 membrane inside the reaction chamber body 12, which can not only isolate the gas inside and outside the organic-inorganic hybrid SiO2 membrane, but also seal it from the outside.

[0034] When in use, firstly connect the organic-inorganic hybrid SiO2 membrane 15 with the lower inner lining membrane sealing ring 8, the pressure ring 11, and the lower nut 7 of the reactor by threaded matching, put the lower nut sealing ring 10 into the lower nut sealing ring groove 9, and tighten the lower pressure cover 5 with the matched lower nut 7 and the lower end of the reaction chamber body 12 by threaded matching; at the upper end of the organic-inorganic hybrid SiO2 membrane 15, the upper inner lining membrane sealing ring 19 is sleeved on the outer wall of the organic-inorganic hybrid SiO2 membrane, and the upper nut sealing ring 17 is placed in the upper nut sealing ring groove 16. After matching the boss of the upper nut 18 of the reactor with the upper nut sealing ring groove 16, the upper pressure cover 2 is tightened by external force to fix the organic-inorganic hybrid SiO2 membrane of the membrane reactor. And seal; the inert carrying gas inlet 1 and the inert carrying gas outlet 6 are respectively connected to the one-eighth inch NPT to one-eighth inch ferrule interface and connected to the corresponding pipeline; the reaction gas inlet 3 and the reaction gas outlet 4 pipelines are respectively connected to the one-quarter inch ferrule interface and connected to the corresponding pipeline; open the catalyst feed port 14, the one-quarter inch welding head ferrule plug, slowly add the Cu-ZnO-A1203-ZrO2 catalyst required for the reaction to the Cu-ZnO-A1203-ZrO2 catalyst layer 13 in the gap between the outer wall of the organic-inorganic hybrid SiO2 membrane 15 and the inner wall of the reaction chamber body 12, and then tighten the plug of the catalyst feed port 14. At this time, the overall connection step of the membrane reactor is completed. The operating temperature of this reactor is 200-450℃, the operating pressure is 2-5MPa, and the catalyst inside needs to be filled with 1ml.

[0035] The innovation of the present invention patent application is to prepare an organic-inorganic hybrid SiO2 film 15 using 1,2-bis(triethoxysilyl)ethane (BTESE) as a precursor. The specific preparation method is as follows:

[0036] (1) Preparation of aluminum isopropoxide sol

[0037] In order to prepare the α-Al2O3 / γ-Al2O3 support, the aluminum isopropoxide sol must be prepared first. Specifically, 0.075 mol of aluminum isopropoxide is accurately weighed, ground into powder using an agate mortar, and added in batches to a round-bottom flask containing a certain volume of 84°C hot water, where n(H2O):n(aluminum isopropoxide)=100:1, refluxed and stirred at this temperature for 100 minutes, then heated to 90°C and left open for 90 minutes to volatilize the generated isopropanol, completing the hydrolysis step; 1.8 mol·L –1 Take 10 mL of nitric acid solution and add it to the completely evaporated aluminum isopropoxide solution to complete the peptization step, then reflux and stir for 24 hours at the same temperature to complete the aging step; add an appropriate volume of 5 wt% polyvinyl alcohol solution, continue to reflux and stir for 2 hours, take it out and let it stand and cool for use.

[0038] (2) Preparation of α-Al2O3 / γ-Al2O3 support

[0039] The commercial α-Al2O3 tube with a pore size of 100 nm was coated with a uniform aluminum isopropoxide sol by the dip-pulling method and placed in a humidity incubator (humidity of 65±5%, temperature of 20±2°C) to dry for more than 24 hours. Then it was placed in a high-temperature sintering furnace for calcination. The temperature was controlled as follows: from room temperature to 10°C min –1 The heating rate was increased to 300℃ and kept at this temperature for 2h; the heating rate was increased from 300℃ to 2℃min –1 The heating rate was increased to 700℃ and kept at this temperature for 2h; the heating rate was increased from 700℃ to 5℃min –1 The cooling rate was reduced to 500℃, and then naturally cooled to room temperature to prepare the α-Al2O3 / γ-Al2O3 support. The thickness of the γ-Al2O3 layer can be controlled by the immersion time, number of immersions, pulling speed and sol concentration.

[0040] (3) Preparation of BTESE sol

[0041] First, 10 mL of BTESE and anhydrous ethanol were poured into a 50 mL conical flask and mixed evenly by magnetic stirring. Then, the conical flask was taken out and placed in an ice bath. 5 mL of nitric acid (1 mol·L -1 ) and 20 mL of anhydrous ethanol were mixed in a beaker. Then, the mixed solution of nitric acid and anhydrous ethanol was added dropwise to the mixed solution of BTESE and anhydrous ethanol using a constant pressure funnel. The solution was stirred continuously during the addition process to avoid excessive local concentration. The stirring speed was 200 r·min -1 The above solution was then placed in a water bath at 60°C and refluxed for 1.5 hours to obtain a BTESE sol having a formula of

[0042] n(BTESE):n(H2O):n(EtOH):n(H + )=1:22.24:26.12:0.2.

[0043] (4) Preparation of BTESE membrane

[0044] Take an appropriate amount of sol and dilute it five times with anhydrous ethanol. The diluted sol is the coating liquid. Dip and pull once on the surface of the homemade α-Al2O3 / γ-Al2O3 support, place the membrane tube in a humidity incubator at a temperature of 40°C and a relative humidity of 25% to dry for 3 hours, and then place the membrane tube in a tubular furnace for calcination at a calcination temperature of 400°C, a holding time of 3 hours, and a heating / cooling rate of 0.5°C / min. To avoid the influence of particles in the air, the sol synthesis and coating process are completed in a clean laboratory.

[0045] In the actual production, the commercial α-Al2O3 tube with a pore size of 100nm was coated with a uniform aluminum isopropoxide sol by the dip-pulling method. The dipping time was 3s, and a defect-free γ-Al2O3 layer was prepared. Then, the α-Al2O3 / γ-Al2O3 support was coated with a uniform BTESE sol coating liquid by the dip-pulling method. The dipping time was 15s, and a BTESE membrane tube with a defect-free three-layer asymmetric structure was prepared. Then, the Cu-based catalyst Cu-ZnO-A1203-ZrO2 catalyst was filled outside the membrane tube. The catalyst layer 13 was used to construct a bifunctional reaction system of a BTESE membrane reactor coupled with a Cu-based catalyst, and applied it to the catalytic hydrogenation of CO2 to produce methanol. The results showed that the prepared BTESE membrane was uniformly attached to the outside of the γ-Al2O3 mesoporous membrane tube and still maintained a certain structural integrity after use. Under the conditions of 300°C, 3MPa, and W / F=10h, the CO2 conversion rate reached a maximum of 27.64%, and the methanol yield was 26.50%, which were 7.3 times and 7.1 times higher than those of the traditional fixed-bed reactor in the prior art, respectively.

[0046] The membrane reactor of the present invention is applied to the reaction of catalytic conversion of CO2 hydrogenation to produce methanol, and the specific embodiments are as follows: Examples 1-3.

[0047] Example 1

[0048] (1) 2.0 g of the prepared Cu-ZnO-A1203-ZrO2 catalyst and 15.0 g of quartz sand were placed in a membrane reactor device for reduction, wherein the tube material in the membrane reactor device was an organic-inorganic hybrid SiO2 membrane. High-purity H2 was introduced into the membrane reactor device at a space velocity of W / F=10 h, and the reduction temperature of the membrane reactor device was controlled to be 300° C. (programmed temperature), the pressure was 0.2 MPa, and the introduction time was 6 h, so that the inner cavity and the outer cavity of the membrane reactor device maintained a reducing atmosphere.

[0049] (2) After the reduction is completed, the temperature is lowered and the raw gas is switched to react. The raw gas composition is

[0050] CO2 / H2 / N2=24 / 72 / 4 (W / F=10h), the purge gas is high-purity He (W / F=50h), and the purpose of the purge gas is to promptly remove the H2O and methanol that penetrate into the tube from outside. The reaction temperature is 200°C and the reaction pressure is 3MPa.

[0051] Example 2

[0052] (1) 2.0 g of the prepared Cu-ZnO-A1203-ZrO2 catalyst and 15.0 g of quartz sand were placed in a membrane reactor device for reduction, wherein the tube material in the membrane reactor device was an organic-inorganic hybrid SiO2 membrane. High-purity H2 was introduced into the membrane reactor device at a space velocity of W / F=10 h, and the reduction temperature of the membrane reactor device was controlled to be 300° C. (programmed temperature), the pressure was 0.2 MPa, and the introduction time was 6 h, so that the inner cavity and the outer cavity of the membrane reactor device maintained a reducing atmosphere.

[0053] (2) After the reduction is completed, the temperature is lowered and the raw gas is switched to react. The raw gas composition is

[0054] CO2 / H2 / N2=24 / 72 / 4 (W / F=10h), the purge gas is high-purity He (W / F=50h), and the purpose of the purge gas is to promptly remove the H2O and methanol that penetrate into the tube from outside. The reaction temperature is 300°C and the reaction pressure is 2MPa.

[0055] Example 3

[0056] (1) 2.0 g of the prepared Cu-ZnO-A1203-ZrO2 catalyst and 15.0 g of quartz sand were placed in a membrane reactor device for reduction, wherein the tube material in the membrane reactor device was an organic-inorganic hybrid SiO2 membrane. High-purity H2 was introduced into the membrane reactor device at a space velocity of W / F=10 h, and the reduction temperature of the membrane reactor device was controlled to be 300° C. (programmed temperature), the pressure was 0.2 MPa, and the introduction time was 6 h, so that the inner cavity and the outer cavity of the membrane reactor device maintained a reducing atmosphere.

[0057] (2) After the reduction is completed, the temperature is lowered and the raw gas is switched to react. The raw gas composition is

[0058] CO2 / H2 / N2=24 / 72 / 4 (W / F=10h), the purge gas is high-purity He (W / F=50h), and the purpose of the purge gas is to promptly remove the H2O and methanol that penetrate into the tube from outside. The reaction temperature is 450°C and the reaction pressure is 5MPa.

[0059] Although the embodiments of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments.

Claims

1. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation, characterized in that: The invention comprises a membrane reaction chamber body (12), a Cu-ZnO-Al2O3-ZrO2 catalyst layer (13) is coaxially arranged inside the reaction chamber body (12), and an organic-inorganic hybrid SiO2 membrane (15) is coaxially arranged inside the Cu-ZnO-Al2O3-ZrO2 catalyst layer (13). An inert gas inlet (1) is connected to the top of the reaction chamber body (12), and an inert gas outlet (6) is connected to the bottom of the reaction chamber body (12). On one side of the reaction chamber body (12), an air inlet pipe (3) and an air outlet pipe (4) are arranged in sequence from top to bottom at 40 mm and 95 mm from the top of the reaction chamber body (12), and the length of the air inlet pipe (3) and the air outlet pipe (4) is 95 mm. On the other side of the reaction chamber body (12), a catalyst feed port (14) is arranged at 48 mm from the top of the reaction chamber body (12) and is connected to the Cu-ZnO-Al2O3-ZrO2 catalyst layer (13). When the reactor is manufactured, an impregnation-pulling method is used to deposit a catalyst in a commercial α-Al2O3 catalyst layer with a pore size of 100 nm. 2O3 tube was uniformly coated with isopropanol aluminum sol for 3 seconds to prepare a defect-free α-Al2O3 / γ-Al2O3 support; then, the α-Al2O3 / γ-Al2O3 support was uniformly coated with BTESE sol coating liquid by the immersion-pulling method for 15 seconds to prepare a BTESE membrane tube with a defect-free three-layer asymmetric structure, namely the organic-inorganic hybrid SiO2 membrane (15); then, a Cu-based catalyst Cu-ZnO-A1203-ZrO2 catalyst was filled outside the membrane tube to form a Cu-ZnO-A1203-ZrO2 catalyst layer (13), thereby constructing a dual-functional reactor reaction system of an organic-inorganic hybrid SiO2 membrane (15) reactor coupled with a Cu-based catalyst.

2. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 1, characterized in that: The preparation method of the organic-inorganic hybrid SiO2 film (15) is as follows: Step 1: Preparation of α-Al2O3 / γ-Al2O3 support The α-Al2O3 / γ-Al2O3 support was prepared by coating the commercial α-Al2O3 tube with a pore size of 100 nm with a uniform aluminum isopropoxide sol by the dip-pulling method, placing it in a humidity incubator for more than 24 hours, and then placing it in a high-temperature sintering furnace for a temperature rise and fall vacant calcination process, and then naturally cooling it to room temperature. Step 2: Preparation of BTESE sol First, 10 mL of BTESE and anhydrous ethanol were poured into a 50 mL conical flask and mixed evenly by magnetic stirring. Then, the conical flask was taken out and placed in an ice bath. 5 mL of 1 mol·L -1 Nitric acid and 20 mL of anhydrous ethanol were mixed evenly in a beaker. The mixed solution of nitric acid and anhydrous ethanol was added dropwise into the mixed solution of BTESE and anhydrous ethanol using a constant pressure funnel. The stirring speed was 200 r·min. -1， The above solution was then placed in a water bath at 60°C and refluxed for 1.5 h to obtain a BTESE sol having a formula of n(BTESE):n(H2O):n(EtOH):n(H + )=1:22.24:26.12:0.2; (3) Preparation of BTESE membrane Take the sol and dilute it five times with anhydrous ethanol. The diluted sol is the coating liquid. It is dipped and pulled once on the surface of a homemade α-Al2O3 / γ-Al2O3 support. The membrane tube is placed in a humidity incubator at a temperature of 40°C and a relative humidity of 25% to dry for 3 hours. Then the membrane tube is placed in a tubular furnace and calcined at a calcination temperature of 400°C, a holding time of 3 hours, and a heating / cooling rate of 0.5°C / min.

3. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 2, characterized in that: The preparation method of the aluminum isopropoxide sol comprises: weighing 0.075 mol of aluminum isopropoxide, grinding it into powder with an agate mortar, adding it into a round-bottom flask containing 84° C. hot water in batches, wherein n(H2O):n(aluminum isopropoxide)=100:1, stirring under reflux at 84° C. for 100 min, then heating to 90° C., opening for 90 min, and preparing 1.8 mol·L –1 Take 10 mL of nitric acid solution and add it to the completely evaporated aluminum isopropoxide solution, then reflux and stir at 90°C for 24 hours, add 5wt% polyvinyl alcohol solution, continue to reflux and stir for 2 hours, take it out and let it stand and cool for use.

4. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 2, characterized in that: The humidity of the incubator is 65±5% and the temperature is 20±2°C.

5. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 2, characterized in that: The temperature rise and fall idling roasting procedure includes: from room temperature to 10℃min –1 The heating rate was increased to 300℃, kept at this temperature for 2h, and then increased from 300℃ to 2℃min –1 The heating rate was increased to 700℃, kept at this temperature for 2h, and then increased from 700℃ to 5℃min –1 The cooling rate dropped to 500°C.

6. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 1, characterized in that: The inert carrier gas inlet (1) is connected to the top of the reaction chamber body (12) through the reactor upper nut (18), and the inert carrier gas outlet (6) is connected to the bottom of the reaction chamber body (12) through the reactor lower nut (7).

7. The novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 1 is characterized in that: The upper part of the organic-inorganic hybrid SiO2 film (15) is fixed to the upper nut (18) of the reactor via an upper inner lining film sealing ring (19), and the lower part of the organic-inorganic hybrid SiO2 film (15) is fixed to the lower nut (7) of the reactor via a lower inner lining film sealing ring (8).

8. The novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 1 is characterized by: An upper pressure cover (2) of the reactor is coaxially arranged outside the inert carrier gas inlet (1), and a lower pressure cover (5) of the reactor is coaxially arranged outside the inert carrier gas outlet (6).

9. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 8, characterized in that: Inside the reactor upper pressure cover (2), the reactor upper nut (18) realizes the sealing of the reactor upper part through the upper nut sealing ring groove (16) and the upper nut sealing ring (17), and inside the reactor lower pressure cover (5), the reactor lower nut (7) realizes the sealing of the reactor lower part through the lower nut sealing ring groove (9) and the lower nut sealing ring (10).

10. A novel membrane reactor for producing methanol by catalytic conversion of CO2 hydrogenation according to claim 9, characterized in that: Inside the lower pressure cover (5) of the reactor, below the organic-inorganic hybrid SiO2 film (15), a pressure ring (11) is coaxially arranged with the organic-inorganic hybrid SiO2 film (15).

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