Sodium superionic conductor catalysts containing metal oxide coatings, and methods of making and using the same

Abstract

The application discloses a sodium superionic conductor catalyst containing a metal oxide coating and a preparation method and application thereof, and the catalyst comprises a Ti, Zr and Ce metal oxide coating component and element components Ti, P, S, O and H constituting a main structure of the sodium superionic conductor, and the mass percentage components are as follows: MeO2: 2.5-20%; H 1‑x Ti2(PO4) 3‑x (SO4) x : 80-97.5%, wherein the metal Me in the coating component is one of Ti, Zr and Ce or any two combinations, and x=0.4-1. The application first uses a metal oxide coating and a sodium superionic conductor to prepare a catalyst, the external coating structure can play a self dehydrogenation role, and the coating effect can promote a subsequent reaction; a synthesis catalyst method is simple, synthesis cost is low, and batch production is easy; the catalyst is used for directly synthesizing propylene acid and methyl propylene acid from methanol and acetic acid, product selectivity is high, separation is easy, and the industrial application prospect is wide.

Description

Technical Field

[0001] This invention relates to a sodium superionic conductor catalyst with a metal oxide coating, its preparation method and application, belonging to the field of catalyst preparation and application technology. Background Technology

[0002] Acrylic acid, as one of the simplest unsaturated carboxylic acids, is widely used in coatings, chemical fibers, superabsorbent polymers, adhesives, leather, and papermaking. Research on acrylic acid production processes has long been a focus worldwide. Currently, acrylic acid production is mainly achieved through a two-step propylene oxidation process. However, the raw material propylene for this route is highly susceptible to fluctuations in oil prices. Furthermore, with continued economic development, the demand for acrylic acid is increasing year by year. Exploring synthetic routes for coal-based acrylic acid, such as methanol / formaldehyde and acetic acid condensation, is of significant strategic importance.

[0003] For coal-based routes, the most studied process is the condensation of formaldehyde and acetic acid hydroxyl condensation to prepare acrylic acid. According to literature reports, acidic catalysts, represented by VPO [M. Ai, J. Catal. 124 (1990) 293-296. M.Ai, J. Catal., 124 (1990) 293-296], and basic catalysts, represented by Cs-based catalysts [M. Ai, et al. Appl. Catal. A-Gen., 288 (2005) 211-215], exhibit good catalytic activity. [M. Ai, et al. Bull. Chem. Soc. Jpn., 63(1990), 199-202; XZ Feng, et al. 314 (2014) 132-141]. However, in this process, formaldehyde is chemically reactive and readily polymerizes, requiring the use of low-concentration aqueous solutions for storage and transportation. When acrylic acid is synthesized using formaldehyde aqueous solution as a raw material, the large amount of water in the system can cause the VPO catalyst to pulverize and clog the reactor. In addition, due to the high reaction temperature, some unreacted formaldehyde escapes from the solution and polymerizes in the pipeline, causing blockages, which will limit its large-scale application.

[0004] In comparison, the direct synthesis of acrylic acid from methanol and acetic acid not only shortens the reaction process and reduces costs, but also offers significant advantages due to the superior safety and stability of methanol compared to formaldehyde. This makes it a highly promising technological route for extending the methanol industry chain. The direct synthesis of acrylic acid from methanol and acetic acid involves two main steps: methanol dehydrogenation to formaldehyde, and the condensation of formaldehyde with acetic acid to acrylic acid. These two reactions require different active sites and have significantly different reaction temperatures, thus requiring highly versatile catalysts to achieve this process. A few studies have reported on the direct synthesis of acrylic acid (methyl acrylate) from methanol and acetic acid, primarily using VPO catalysts [M. Ai, et al. Bull. Chem. Soc. Jpn., 63(1990), 199-202; XZ Feng, et al. 314 (2014) 132-141; LQ Shen, et al (97) 2019 2699-2707]. Related results show that the selectivity of the target products, acrylic acid and methyl acrylate, is less than 30%. Chinese patent CN109364967A discloses a technique for synthesizing acrylic acid from methanol and methyl acetate using a sodium superionic conductor catalyst. This patent describes the preparation of a multifunctional catalyst modified with low-loading vanadium oxide, achieving a one-step synthesis of acrylic acid and methyl acrylate from methanol and methyl acetate. However, this invention still introduces a small amount of highly toxic vanadium (V). Developing novel catalysts for the direct synthesis of acrylic acid from methanol and acetic acid that are low in toxicity, highly active, highly stable, and inexpensive is essential. Chinese patent CN115090308A discloses a metal-doped sodium superionic catalyst, its preparation method, and its application. This patent further improves the catalyst preparation method by in-situ doping Mn, Y, Mo, Bi, and Re metals into the sodium superionic conductor material, achieving better catalytic performance for the one-step synthesis of acrylic acid and methyl acrylate from methanol and acetic acid. However, most of these introduced components are precious metals, while using inexpensive metals to achieve equivalent catalytic performance is significant for reducing production costs.

[0005] Therefore, continuous improvement of catalyst preparation methods or exploration of new catalyst preparation methods to synthesize target products more efficiently will be a necessary stage to achieve industrialization. Summary of the Invention

[0006] This invention aims to provide a sodium superionic conductor catalyst with a metal oxide coating, its preparation method, and its applications. The catalyst exhibits simple preparation process, low cost, high thermal stability, and high activity. The catalyst of this invention is an H₂ catalyst with a sodium superionic structure. 1-x Ti2(PO4) 3-x (SO4) x@MeO2 (where Me = Ti, Zr, Ce, etc., x = 0.4–1) material, this catalyst can be used for the direct synthesis of acrylic acid and methyl acrylate from methanol and acetic acid.

[0007] In this invention, the sodium superionic conductor catalyst with a metal oxide coating is mainly composed of a sodium superionic conductor host structure and a metal oxide coating component. A significant feature of this material is the close contact between the coating and the core, resulting in excellent encapsulation and providing bifunctional active sites for both methanol dehydrogenation and aldol condensation. Furthermore, these active sites exhibit good matching, demonstrating efficient synergy within the 340℃-380℃ temperature range. The catalyst obtained in this invention exhibits excellent catalytic performance for the direct synthesis of acrylic acid and methyl acrylate from methanol and acetic acid. The catalyst components are all common metal salts and oxides, the preparation conditions are simple, the catalyst preparation has good reproducibility, the coating structure is novel, and the preparation method does not involve complex operations, effectively reducing costs.

[0008] This invention provides a sodium superionic conductor catalyst (H) with a metal oxide coating. 1-x Ti2(PO4) 3-x (SO4) x @MeO2), comprising Ti, Zr, Ce metal oxide coating components and elemental components Ti, P, S, O, and H constituting the main structure of the sodium superionic conductor, with a mass percentage composition of MeO2: 2.5%-20%; H 1-x Ti2(PO4) 3-x (SO4) x : 80%-97.5%, wherein the metal Me in the coating component is one or any combination of two of Ti, Zr and Ce, and x=0.4-1.

[0009] This invention provides a method for preparing the above-mentioned sodium superionic conductor catalyst with a metal oxide coating, comprising the following steps:

[0010] (1) Preparation of sodium superionic conductor

[0011] Weigh out solid titanium oxysulfate (TiOSO4) sample and dissolve it in deionized water. The solution is then sonicated to prepare a concentration range of 1.0-2.0 mol / L. 30 wt% hydrogen peroxide is added as a stabilizer, and polyethylene glycol (PEG) as a dispersant. The solution is then sonicated again. Concentrated phosphoric acid (85% wt) is added dropwise in a single batch, and the mixture is stirred vigorously. The resulting solution is placed in a water bath and allowed to stand for 24-48 hours. The resulting dry gel is calcined at 500-700 °C for 5-10 hours to finally obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO4) xThe mass ratio of raw materials (raw powder, synthetic mother liquor, and raw materials) is 10:10-20:6-15:3-5:5-10.

[0012] (2) Preparation of sodium superionic conductor catalysts with metal oxide coatings

[0013] 5.0 g of the sodium superionic conductor material powder obtained in step (1) was placed in 100 mL of anhydrous ethanol, and 0.3-0.5 mL of ammonia water was added. The mixture was ultrasonically dispersed for 15 min. Subsequently, 0.255-5.10 g of organometallic compound was added dropwise to the above mixed solution, and the mixture was stirred in a water bath at 30-60 ℃ for 12-24 h. After centrifugation and drying, the resulting white powder was calcined at 400-600 ℃ for 2-6 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The proportion of the metal oxide MeO2 coating in the catalyst was 2.5wt%-20wt%.

[0014] The organometallic compound includes one or two of the following: n-butyl titanate, titanium acetylacetonate, zirconium n-butoxide, zirconium acetylacetonate, cerium acetate, or cerium tricerocene; when two are selected, they can be in any proportion.

[0015] This invention provides the application of the above-mentioned sodium superionic conductor catalyst with metal oxide coating in the direct synthesis of acrylic acid and methyl acrylate from methanol and acetic acid.

[0016] The application of the above catalyst includes the following steps: The catalyst is used in the direct synthesis of acrylic acid and methyl acrylate from methanol and acetic acid. The catalytic reaction is carried out in a continuous flow fixed-bed reactor, with the catalyst placed in the middle of the reactor and a preheated quartz sand layer on top. The carry-on gas is an oxygen-nitrogen mixture, with an oxygen volume fraction of 2-20%. During the catalytic reaction, the reaction temperature is controlled at 340-380 °C, the reaction pressure is atmospheric pressure, and the gas flow rate of the carry-on gas is controlled at 5-15 mL / min per gram of catalyst. -1 The flow rate was controlled, the molar ratio of methanol to acetic acid was maintained at 0.5-3:1, and the liquid hourly space velocity was controlled at 1-3 mL g / L. -1 ·h -1 The liquid feedstock is introduced using a plunger pump.

[0017] The beneficial effects of this invention are:

[0018] (1) This invention uses the concept and idea of ​​coating catalysis, and for the first time uses metal oxide coating and sodium superionic conductor to prepare catalyst. The external coating structure can play its own dehydrogenation role, and its coating effect can promote the subsequent reaction.

[0019] (2) The raw materials for the synthesis catalyst are readily available, the preparation method is simple, the equipment requirements are low, the synthesis cost is low, and it is easy to mass-produce.

[0020] (3) Using the catalyst of the present invention, methanol and acetic acid can be directly and efficiently converted into acrylic acid and methyl acrylate, with an acetic acid conversion rate of over 60%, a selectivity of over 70% for acrylic acid + methyl acrylate, and a space-time yield of 5.4 mmol·g. -1 ·h -1 The above describes a process that converts excess methanol and acetic acid into high-value-added acrylic acid and methyl acrylate. The reaction operates under mild conditions, without high temperature or pressure, has a simple process route, low equipment requirements, high product selectivity, and is easy to separate, making it a promising candidate for industrial application. Attached Figure Description

[0021] Figure 1 The image shows a TEM image of the catalyst prepared in Example 1.

[0022] Figure 2 The XRD pattern of the catalyst prepared in Example 2.

[0023] Figure 3 The XRD pattern of the catalyst prepared in Example 3.

[0024] Figure 4 The XRD pattern of the catalyst prepared in Example 4 is shown.

[0025] Figure 5 The image shows the XRD pattern of the catalyst prepared in Example 5.

[0026] Figure 6 The image shows the XRD pattern of the catalyst prepared in Example 6.

[0027] Figure 7 TEM image of the catalyst prepared in Example 7.

[0028] Figure 8 The XRD pattern of the catalyst prepared in Example 8.

[0029] Figure 9 The XRD pattern of the catalyst prepared in Example 9. Detailed Implementation

[0030] The present invention will be further illustrated by the following embodiments, but is not limited to the following embodiments. Example 1

[0031] (1) Preparation of sodium superionic conductor

[0032] 17.60 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 35.2 g of deionized water was added. 26.4 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 8.8 g of polyethylene glycol (PEG) was added as a dispersant. The mixture was then sonicated to dissolve the precipitate. 14.46 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The solution was dried in a 45 ℃ water bath for 48 h. The resulting dry gel was calcined at 600 ℃ for 10 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0033] (2) Preparation of sodium superionic conductor catalyst with TiO2 metal oxide coating

[0034] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.3 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 1.60 g of tetrabutyl titanate was added to the above mixed solution, and the mixture was stirred in a water bath at 30 ℃ for 24 h. After centrifugation and drying, the resulting white powder was calcined at 500 ℃ for 2 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The TiO2 metal oxide coating accounted for 7.0% of the catalyst.

[0035] Figure 1 The TEM spectrum of the catalyst prepared in this embodiment is shown. It can be seen from the figure that most of TiO2 is coated on the surface of the NASICON catalyst in the form of a coating, and the very small amount of TiO2 particles that are present have little effect on the catalytic activity.

[0036] The synthesis of acrylic acid from methanol and acetic acid is carried out in a fixed-bed reactor. 2g of the above catalyst is placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction proceeds at 30 mL / min. -1 The mixture of oxygen and nitrogen in a gas stream with an oxygen volume fraction of 20% is heated to 380℃. A mixture of methanol and acetic acid in a molar ratio of 2:1 is then introduced at a rate of 1.5 mL / h. -1 ·g -1 The feed air velocity was injected into the reaction system, and the reaction pressure was controlled at 0.1 MPa. The feed passed through a magnetic ring preheating zone, reacted in the catalytic bed, and the product was introduced into a cold trap absorption device for gas-liquid separation, collecting the liquid phase product. The reaction was carried out for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 76%, the selectivity of acrylic acid and methyl acrylate among the main products was 80.3%, and the space-time yield was 6.58 mmol·g⁻¹. -1 ·h -1The selectivity for methyl acetate was 9.6%, for dimethyl ether 4.5%, formate 2.1%, for propionaldehyde 0.2%, for acrolein 0.3%, for propionic acid 0.4%, and for gaseous products 2.6%. Example 2

[0037] (1) Preparation of sodium superionic conductor

[0038] 14.80 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 24.84 g of deionized water was added. 13.8 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 4.41 g of polyethylene glycol (PEG) was added as a dispersant. The mixture was then sonicated to dissolve the precipitate. Finally, 10.48 g of 85 wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The solution was dried in a 45°C water bath for 24 h. The resulting dry gel was calcined at 550°C for 6 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0039] (2) Preparation of sodium superionic conductor catalyst with CeO2 metal oxide coating

[0040] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol and 0.3 ml of ammonia water was added. The mixture was ultrasonically dispersed for 15 min. Then, 0.23 g of cerium acetate (Ce(C2H3O2)3·nH2O) was added to the above mixed solution and stirred in a water bath at 40℃ for 24 h. After centrifugation and drying, the resulting white powder was calcined at 400℃ for 4 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The proportion of the metal oxide CeO2 coating in the catalyst was 2.5%. The X-ray electron diffraction pattern of the prepared catalyst is as follows:

[0041] Figure 2 The XRD pattern of the catalyst prepared in this embodiment is shown. The figure shows that the catalyst is mainly composed of the NASICON phase, but the degree of crystallization is poor and no characteristic diffraction peaks of CeO2 were observed.

[0042] The synthesis of acrylic acid from methanol and acetic acid is carried out in a fixed-bed reactor. 2 g of the above catalyst is placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction proceeds at a rate of 25 mL / min. -1 The oxygen-nitrogen mixture with an oxygen volume fraction of 10% is heated to 360℃. A methanol-acetic acid mixture with a molar ratio of 1:1 is then introduced at a rate of 2 mL / h. -1 ·g -1The feed rate was controlled at 0.1 MPa when the reaction pressure was maintained at the reaction pressure. The raw material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 73.5%, the selectivity for acrylic acid and methyl acrylate among the main products was 79.3%, and the space-time yield was 11.77 mmol·g⁻¹. -1 ·h -1 The selectivity for methyl acetate was 15.5%, for dimethyl ether was 0.1%, formate was 0.2%, for propionaldehyde was 0.3%, for acrolein was 1.2%, for propionic acid was 0.4%, and for gaseous products was 3.0%. Example 3

[0043] (1) Preparation of sodium superionic conductor

[0044] 21.93 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 21.12 g of deionized water was added. 15.84 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 7.04 g of polyethylene glycol (PEG) was added as a dispersant. The mixture was then sonicated to dissolve the precipitate. 13.24 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The solution was dried in a 50°C water bath for 36 h. The resulting dry gel was calcined at 500°C for 8 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0045] (2) Preparation of sodium superionic conductor catalyst with TiO2 metal oxide coating

[0046] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.3 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 2.1 g of tetrabutyl titanate was added to the above mixed solution, and the mixture was stirred in a water bath at 50 ℃ for 18 h. After centrifugation and drying, the resulting white powder was calcined at 700 ℃ for 2 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The TiO2 metal oxide coating accounted for 9.0% of the catalyst. The X-ray electron diffraction pattern of the prepared catalyst is as follows.

[0047] Figure 3 The XRD pattern of the catalyst prepared in this embodiment is shown. The figure shows that the synthesized catalyst exhibits good NASICON crystal phase diffraction peaks, and no characteristic peaks of the TiO2 coating were observed, indicating that it is well dispersed.

[0048] The synthesis of acrylic acid from methanol and acetic acid was carried out in a fixed-bed reactor. 2 g of the above catalyst was placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction was carried out at a rate of 12 mL / min. -1 The temperature is raised to 380℃ in an oxygen-nitrogen mixed gas stream with an oxygen volume fraction of 15%. A mixture of methanol and acetic acid with a molar ratio of 3:1 is then introduced at a rate of 3 mL / h. -1 ·g -1 The feed rate was controlled at 0.1 MPa when the reaction pressure was maintained at the reaction pressure. The raw material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 63%, the selectivity for acrylic acid and methyl acrylate among the main products was 76.2%, and the space-time yield was 8.11 mmol·g⁻¹. -1 ·h -1 The selectivity for methyl acetate was 15.1%, for dimethyl ether 3.3%, formate 1.2%, for propionaldehyde 0.4%, for acrolein 0.6%, for propionic acid 0.4%, and for gaseous products 2.8%. Example 4

[0049] (1) Preparation of sodium superionic conductor

[0050] 28.92 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 21.35 g of deionized water was added. Next, 22.53 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 5.93 g of polyethylene glycol (PEG) was added as a dispersant. The mixture was then sonicated to dissolve the precipitate. Finally, 14.46 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The solution was dried in a 60°C water bath for 36 h. The resulting dry gel was calcined at 600°C for 5 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0051] (2) Preparation of sodium superionic conductor catalyst with TiO2 metal oxide coating

[0052] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.5 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 1.12 g of tetrabutyl titanate was added to the above mixed solution, and the mixture was stirred in a water bath at 40 °C for 12 h. After centrifugation and drying, the resulting white powder was calcined at 600 °C for 6 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The TiO2 metal oxide coating accounted for 5.0% of the catalyst. The X-ray electron diffraction pattern of the prepared catalyst is as follows:

[0053] Figure 4 The XRD pattern of the catalyst prepared in this embodiment is shown. The figure shows that increasing the Ti / P ratio of the synthesized NASICON material can further enhance the crystallinity of the sample, and no characteristic peaks of the introduced TiO2 coating were observed.

[0054] The synthesis of acrylic acid from methanol and acetic acid was carried out in a fixed-bed reactor. 2 g of the above catalyst was placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction was carried out at a rate of 22 mL / min. -1 The mixture of oxygen and nitrogen with an oxygen volume fraction of 8% is heated to 360 °C. A mixture of methanol and acetic acid with a molar ratio of 1:1 is then introduced at a rate of 1 mL·h. -1 ·g -1 The feed rate was controlled at 0.1 MPa when the reaction pressure was maintained at the reaction pressure. The raw material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 81%, the selectivity for acrylic acid and methyl acrylate among the main products was 73.2%, and the space-time yield was 5.99 mmol·g⁻¹. -1 ·h -1 The selectivity for methyl acetate was 12.3%, for dimethyl ether was 7.56%, formate was 2.1%, for propionaldehyde was 0.1%, for acrolein was 0.5%, for propionic acid was 0.3%, and for gaseous products was 3.94%. Example 5

[0055] (1) Preparation of sodium superionic conductor

[0056] 26.72 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 29.39 g of deionized water was added. 24.05 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 10.69 g of polyethylene glycol (PEG) was added as a dispersant. The mixture was then sonicated to dissolve the precipitate. Finally, 20.23 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The solution was dried in a 55°C water bath for 36 h. The resulting dry gel was calcined at 600°C for 10 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0057] (2) Preparation of sodium superionic conductor catalyst with ZrO2 metal oxide coating

[0058] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.3 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 1.2 g of zirconium butoxide was added to the above mixed solution, and the mixture was stirred in a water bath at 60 °C for 24 h. After centrifugation and drying, the resulting white powder was calcined at 500 °C for 6 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The ZrO2 metal oxide coating accounted for 7.14% of the catalyst. The X-ray electron diffraction pattern of the prepared catalyst is as follows:

[0059] Figure 5 The XRD pattern of the catalyst prepared in this embodiment is shown, and the figure shows that no characteristic peaks were found after the introduction of the ZrO2 coating.

[0060] The synthesis of acrylic acid from methanol and acetic acid is carried out in a fixed-bed reactor. 2 g of the above catalyst is placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction proceeds at a rate of 10 mL / min. -1 The mixture of oxygen and nitrogen with an oxygen volume fraction of 15% is heated to 360℃. A mixture of methanol and acetic acid with a molar ratio of 2:1 is then introduced at a rate of 2 mL / h. -1 ·g -1 The feed rate was controlled at 0.1 MPa when the reaction pressure was maintained at the reaction pressure. The raw material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 73.5%, the selectivity for acrylic acid and methyl acrylate among the main products was 70.3%, and the space-time yield was 7.43 mmol·g. -1 ·h -1 The selectivity for methyl acetate was 11.5%, for dimethyl ether was 3.6%, formate was 1.5%, for propionaldehyde was 0.7%, for acrolein was 1.8%, for propionic acid was 1.9%, and for gaseous products was 8.7%. Example 6

[0061] (1) Preparation of sodium superionic conductor

[0062] 22.73 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 55.46 g of deionized water, 41.60 g of 30 wt% hydrogen peroxide as a stabilizer, and 8.319 g of polyethylene glycol (PEG) as a dispersant were added. The mixture was then sonicated to dissolve the sample. Next, 18.91 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The resulting solution was dried in a 55°C water bath for 24 h. The resulting dry gel was calcined at 500°C for 10 h to finally obtain the sodium superionic conductor (H). 1-x Ti2(PO4)3-x (SO 4)x Raw material powder.

[0063] (2) Preparation of sodium superionic conductor catalyst with TiO2 metal oxide coating

[0064] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.4 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 5.32 g of tetrabutyl titanate was added to the above mixed solution, and the mixture was stirred in a water bath at 50 °C for 20 h. After centrifugation and drying, the resulting white powder was calcined at 400 °C for 4 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The TiO2 metal oxide coating accounted for 20% of the catalyst. The X-ray electron diffraction pattern of the prepared catalyst is as follows:

[0065] Figure 6 The XRD pattern of the catalyst prepared in this embodiment is shown. The figure shows that the introduction of a large amount of TiO2 coating (20%) can be observed with its characteristic peaks, which indicates that the increased loading of TiO2 will crystallize and form TiO2 crystals.

[0066] The synthesis of acrylic acid from methanol and acetic acid is carried out in a fixed-bed reactor. 2g of the above catalyst is placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction proceeds at 30 mL / min. -1 The mixture of oxygen and nitrogen in a gas stream with an oxygen volume fraction of 4% was heated to 360℃. A mixture of methanol and acetic acid in a molar ratio of 2:1 was then introduced at a rate of 1.4 mL / h. -1 ·g -1 The feed rate was controlled at 0.1 MPa, and the reaction pressure was maintained at 0.1 MPa. The raw material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 79.8%, the selectivity for acrylic acid and methyl acrylate among the main products was 70.3%, and the space-time yield was 5.45 mmol·g⁻¹. -1 ·h -1 The selectivity for methyl acetate was 12.7%, for dimethyl ether was 9.5%, formate was 1.3%, for propionaldehyde was 0.7%, for acrolein was 0.3%, for propionic acid was 0.6%, and for gaseous products was 4.6%. Example 7

[0067] (1) Preparation of sodium superionic conductor

[0068] 31.76 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 47.64 g of deionized water, 23.82 g of 30 wt% hydrogen peroxide as a stabilizer, and 14.29 g of polyethylene glycol (PEG) as a dispersant were added to the sample. The mixture was then dissolved by ultrasonication. Next, 22.65 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The resulting solution was dried in a 50°C water bath for 48 h. The resulting dry gel was calcined at 600°C for 10 h to finally obtain the sodium superionic conductor (H). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0069] (2) Preparation of sodium superionic conductor catalyst with TiO2 metal oxide coating

[0070] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.3 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 1.60 g of tetrabutyl titanate was added to the above mixed solution, and the mixture was stirred in a water bath at 50 °C for 12 h. After centrifugation and drying, the resulting white powder was calcined at 650 °C for 5 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The TiO2 metal oxide coating accounted for 7.5% of the catalyst. The SEM image of the prepared sample is shown below:

[0071] Figure 7 The TEM spectrum of the catalyst prepared in this embodiment is shown. It can be seen from the figure that most of the TiO2 is coated on the outside of the NASICON material, forming a good coating.

[0072] The synthesis of acrylic acid from methanol and acetic acid is carried out in a fixed-bed reactor. 2 g of the above catalyst is placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction proceeds at 16 mL / min. -1 The temperature is raised to 340℃ in an oxygen-nitrogen mixed gas stream with an oxygen volume fraction of 4%. A methanol and acetic acid mixture with a molar ratio of 1:1 is then introduced at a rate of 2 mL / h. -1 ·g -1 The feed rate was controlled at 0.1 MPa, and the reaction pressure was maintained at 0.1 MPa. The raw material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 76.5%, the selectivity for acrylic acid and methyl acrylate among the main products was 70.0%, and the space-time yield was 10.81 mmol·g⁻¹. -1 ·h -1The selectivity for methyl acetate was 21.7%, for dimethyl ether was 1.1%, for methyl formate was 0.8%, for propionaldehyde was 1.7%, for acrolein was 0.2%, for propionic acid was 0.7%, and for gaseous products was 3.8%. Example 8

[0073] (1) Preparation of sodium superionic conductor

[0074] 17.60 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 20.58 g of deionized water was added. Next, 22.92 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 7.56 g of polyethylene glycol (PEG) was added as a dispersant. The mixture was then sonicated to dissolve the precipitate. Finally, 14.64 g of 85% wt% concentrated phosphoric acid was added dropwise, followed by vigorous stirring. The solution was dried in a 50°C water bath for 36 h. The resulting dry gel was calcined at 600°C for 7 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0075] (2) Preparation of sodium superionic conductor catalyst with ZrO2 metal oxide coating

[0076] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.3 ml of ammonia was added. The mixture was ultrasonically dispersed for 15 min. Then, 1.0 g of zirconium butoxide was added to the above mixed solution, and the mixture was stirred in a water bath at 60 °C for 24 h. After centrifugation and drying, the resulting white powder was calcined at 550 °C for 3 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The ZrO2 metal oxide coating accounted for 6.0% of the catalyst. The X-ray electron diffraction pattern of the prepared catalyst is as follows:

[0077] Figure 8 The XRD pattern of the catalyst prepared in this embodiment is shown, indicating that no ZrO2 characteristic peaks appeared after the coating was added.

[0078] The synthesis of acrylic acid from methanol and acetic acid was carried out in a fixed-bed reactor. 2 g of the above catalyst was placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction was carried out at a rate of 16 mL / min. -1 The mixture of oxygen and nitrogen with a volume fraction of 4% is heated to 380 °C. A mixture of methanol and acetic acid with a molar ratio of 1:1 is then introduced at a rate of 1 mL / h. -1 ·g -1The feed rate was controlled at 0.1 MPa when the reaction pressure was maintained at the reaction pressure. The feed material passed through a magnetic ring preheating zone and reacted in the catalytic bed. The product was then introduced into a cold trap absorption device for gas-liquid separation, and the liquid phase product was collected. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 78.3%, the selectivity for acrylic acid and methyl acrylate among the main products was 70.1%, and the space-time yield was 5.54 mmol·g⁻¹. -1 ·h -1 The selectivity for methyl acetate was 19.5%, for dimethyl ether was 0.5%, for methyl formate was 0.6%, for propionaldehyde was 1.3%, for acrolein was 1.5%, for propionic acid was 0.7%, and for gaseous products was 5.8%. Example 9

[0079] (1) Preparation of sodium superionic conductor

[0080] 28.56 g of solid titanium oxysulfate (TiOSO4) sample was weighed, and then 42.84 g of deionized water was added. 25.70 g of 30 wt% hydrogen peroxide was added as a stabilizer, and 11.42 g of polyethylene glycol (PEG) as a dispersant, followed by ultrasonic dissolution. Then, 25.37 g of 85% wt% concentrated phosphoric acid was added dropwise, and the mixture was stirred vigorously. The solution was dried in a 50°C water bath for 48 h. The resulting dry gel was calcined at 650°C for 6 h to obtain the sodium superionic conductor (H2O). 1-x Ti2(PO4) 3-x (SO 4)x Raw material powder.

[0081] (2) Preparation of sodium superionic conductor catalysts with TiO2 and CeO2 metal oxide coatings

[0082] 5.0 g of the sodium superionic conductor powder obtained in step (1) was placed in 100 ml of anhydrous ethanol, and 0.5 ml of ammonia water was added. The mixture was ultrasonically dispersed for 15 min. Subsequently, 0.50 g of cerium acetate and 0.60 g of tetrabutyl titanate were added to the above mixed solution, and the mixture was stirred in a water bath at 45 °C for 24 h. After centrifugation and drying, the resulting white powder was calcined at 500 °C for 2 h. The calcined sample was pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst. The proportion of the TiO2-CeO2 mixed coating in the catalyst was 7.6%. The X-ray electron diffraction pattern of the prepared catalyst is as follows:

[0083] Figure 9 The XRD pattern of the catalyst prepared in this embodiment is shown. The figure shows that the crystal structure of NASICON decreased after the Ti / P ratio was reduced, and many titanium pyrophosphate crystal phases appeared. Furthermore, no characteristic peaks of CeO2 and TiO2 were observed after the coating was added.

[0084] The synthesis of acrylic acid from methanol and acetic acid was carried out in a fixed-bed reactor. 2 g of the above catalyst was placed in the middle of the reactor, with the upper part filled with a magnetic ring, and the reaction was carried out at a rate of 28 ml / min. -1 The oxygen-nitrogen mixture with an oxygen volume fraction of 12% is heated to 380℃. A methanol-acetic acid mixture with a molar ratio of 1:1 is then introduced at a rate of 1 mL·h. -1 ·g -1 The feed air velocity was injected into the reaction system, and the reaction pressure was controlled at 0.1 MPa. The feed passed through a magnetic ring preheating zone, reacted in the catalytic bed, and the product was introduced into a cold trap absorption device for gas-liquid separation, collecting the liquid phase product. The reaction proceeded for 2 hours, and the product was collected and analyzed. The conversion rate of acetic acid was 79.34%, the selectivity of acrylic acid and methyl acrylate among the main products was 78.2%, and the space-time yield was 6.27 mmol·g⁻¹. -1 ·h -1 The selectivity for methyl acetate was 12.4%, for dimethyl ether 2.2%, formate 0.4%, for propionaldehyde 1.3%, for acrolein 0.2%, for propionic acid 0.8%, and for gaseous products 4.5%.

Claims

1. A sodium superionic conductor catalyst with a metal oxide coating, characterized in that: Includes the metal oxide coating component MeO2 and the elemental component H that constitutes the main structure of the sodium superionic conductor. 1-x Ti2(PO4) 3-x (SO4) x Its mass percentage composition is MeO2: 2.5%-20%; H 1-x Ti2(PO4) 3-x (SO4) x : 80%-97.5%, wherein the metal Me in the coating component is one or any combination of two of Ti, Zr and Ce, and x=0.4-1.

2. A method for preparing a sodium superionic conductor catalyst with a metal oxide coating as described in claim 1, characterized in that... Includes the following steps: (1) Preparation of sodium superionic conductor: Weigh out solid titanium oxysulfate (TiOSO4) sample and dissolve it in deionized water. The solution is then sonicated to a concentration range of 1.0-2.0 mol / L. Add 30 wt% hydrogen peroxide as a stabilizer and polyethylene glycol (PEG) as a dispersant, and continue sonication. Then, add concentrated phosphoric acid (85% wt) dropwise while stirring vigorously. The resulting solution is placed in a water bath and allowed to age for 24-48 h. The resulting dry gel is calcined at 500-700 ℃ for 5-10 h to finally obtain the sodium superionic conductor H. 1-x Ti2(PO4) 3-x (SO4) x The mass ratio of raw material powder; synthetic mother liquor raw materials, titanium oxysulfate, water, hydrogen peroxide, polyethylene glycol, and phosphoric acid is 10:10-20:6-15:3-5:5-10; (2) Preparation of sodium superionic conductor catalysts with metal oxide coatings: Place 5.0 g of sodium superionic conductor material powder obtained in step (1) into 100 mL of anhydrous ethanol, add 0.3-0.5 mL of ammonia water, and ultrasonically disperse for 15 min; then add 0.255-5.10 g of organometallic compound dropwise to the above mixed solution, and stir in a water bath at 30-60 ℃ for 12-24 h; After centrifugation and drying, the resulting white powder is calcined at 400-600 ℃ for 2-6 h; the calcined sample is pressed into tablets, ground, and sieved into 20-40 mesh particles to obtain the catalyst; the organometallic compound includes one or two of the following: n-butyl titanate, titanium acetylacetonate, zirconium n-butoxide, zirconium acetylacetonate, cerium acetate, or cerium tricerocene; when two are selected, they are in any ratio.

3. The application of the sodium superionic conductor catalyst with a metal oxide coating as described in claim 1 in the direct synthesis of acrylic acid and methyl acrylate from methanol and acetic acid.

4. The application according to claim 3, characterized in that... The process includes the following steps: The catalyst is applied to the direct synthesis of acrylic acid and methyl acrylate from methanol and acetic acid. The catalytic reaction is carried out in a continuous flow fixed-bed reactor, with the catalyst placed in the middle of the reactor and a preheated quartz sand section on top. The carry-on gas is a mixture of oxygen and nitrogen, with an oxygen volume fraction of 2-20%. During the catalytic reaction, the reaction temperature is controlled at 340-380 °C, the reaction pressure is atmospheric pressure, and the gas flow rate of the carry-on gas is controlled at 5-15 mL / min per gram of catalyst. -1 The flow rate was controlled, the molar ratio of methanol to acetic acid was maintained at 0.5-3:1, and the liquid hourly space velocity was controlled at 1-3 mL g / L. -1 ·h -1 The liquid feedstock is introduced using a plunger pump.

5. The application according to claim 4, characterized in that: The acetic acid conversion rate was over 60%, the selectivity for acrylic acid + methyl acrylate was over 70%, and the space-time yield was 5.4 mmol·g. -1 ·h -1 above.

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