A bimetallic oxide catalyst, its preparation method and application

Abstract

This invention relates to a bimetallic oxide catalyst, its preparation method, and its applications. The bimetallic catalyst comprises a zirconium oxide support and a metal M, wherein the metal M is selected from Ga, In, and Zn. The metal M is incorporated into the zirconium oxide support lattice, and the zirconium oxide support is a monoclinic or tetragonal zirconium oxide. This catalyst can be used for the hydrogenation of carbon dioxide to produce methanol and dimethyl ether, and has advantages such as high reactivity, good catalytic stability, and a simple, industrially applicable preparation method.

Description

Technical Field

[0001] This invention belongs to the field of catalytic hydrogenation technology, specifically relating to a bimetallic oxide catalyst, its preparation method, and its application. Background Technology

[0002] With the development of industrial society, massive anthropogenic carbon dioxide emissions have led to a sharp increase in atmospheric carbon dioxide concentration, causing a series of environmental and climate problems. Capturing atmospheric carbon dioxide and converting it into methanol and dimethyl ether along with "green hydrogen" can mitigate the environmental problems caused by massive carbon dioxide emissions. Simultaneously, methanol and dimethyl ether, as important platform molecules, can be further converted into other chemicals, achieving anthropogenic carbon dioxide recycling. Therefore, the hydrogenation of carbon dioxide to produce methanol and dimethyl ether has dual significance.

[0003] CO2 is an inert molecule with extremely high stability. In the process of hydrogenating CO2 to methanol, increasing the reaction temperature is beneficial for improving the CO2 conversion rate; however, with increasing temperature, reverse water-gas shift inevitably occurs. High temperatures lead to a significant decrease in the selectivity of methanol and dimethyl ether, while also accelerating catalyst agglomeration and deactivation. Therefore, designing catalytic systems for the efficient conversion of CO2 to methanol and dimethyl ether under mild conditions has become a hot topic of research.

[0004] Traditional Cu / ZnO / Al2O3 ternary catalysts have been successfully used in the industrial production of methanol from carbon monoxide due to their low cost and excellent catalytic performance. However, direct application of this catalyst to methanol from carbon dioxide produces water as a byproduct, leading to the agglomeration and deactivation of the copper in the catalyst. Currently, the stability and catalytic activity of these catalysts are mainly improved through strategies such as carrier modulation, catalyst modification, or improvements to catalyst preparation methods (Shanghai University of Applied Technology patent CN202111151253.5; Shanxi Coal Chemical Institute patent 200410064574; China Huaneng Group Clean Energy Technology Research Co., Ltd. patent CN202111273325.3). Noble metal catalysts (China Petroleum & Chemical Corporation patent CN201410498074.2) can improve catalytic activity, but their high cost limits their widespread commercial application. In recent years, bimetallic oxide catalysts have attracted much attention due to their excellent stability and catalytic activity (Dalian Institute of Chemical Physics, Chinese Academy of Sciences CN201610826535.3). The solvent evaporation-induced self-assembly method developed by Professor Wu Jianfeng's research group at Lanzhou University to prepare GaZrO xThe catalyst exhibited excellent activity and stability in the hydrogenation of carbon dioxide to methanol and dimethyl ether, demonstrating great industrialization potential (CN113058583A). Previous research by Professor Wu Jianfeng's group at Lanzhou University discovered GaZrO₂... x The catalyst exhibits a mixed crystal structure of monoclinic and tetragonal ZrO2. The crystal form of the catalyst support significantly influences the catalyst activity, but preparing a single-crystal ZrO2 support remains a significant challenge. We aim to develop a method for preparing a bimetallic oxide catalyst with a single monoclinic or tetragonal crystal support, thereby providing a basis for further exploring the relationship between catalyst reactivity and support crystal structure. Summary of the Invention

[0005] This invention provides a method for preparing a bimetallic oxide catalyst and its application in the hydrogenation of carbon dioxide to methanol and dimethyl ether. The catalyst uses a single crystal form, specifically monoclinic or tetragonal ZrO2, as a support, and possesses advantages such as high reactivity, good catalytic stability, and a simple, industrially applicable preparation method.

[0006] First, the present invention provides a bimetallic oxide catalyst comprising a zirconium oxide support and a metal M, wherein the metal M is selected from Ga, In and Zn, and the metal M is incorporated into the zirconium oxide support lattice, wherein the zirconium oxide support is a monoclinic zirconium oxide or a tetragonal zirconium oxide.

[0007] According to some embodiments of the present invention, the zirconium oxide in the catalyst is all monoclinic zirconium oxide.

[0008] According to some embodiments of the present invention, the zirconium oxide in the catalyst is all tetragonal zirconium oxide.

[0009] According to some embodiments of the present invention, in the catalyst, the metal M is Ga.

[0010] According to some embodiments of the present invention, the catalyst has an M / (M+Zr) ratio of 0.1% to 80% by atomic percentage.

[0011] According to some embodiments of the present invention, the catalyst, by mass, has an M / (M+Zr) ratio of 0.1%-30%, for example 1%, 2%, 3%, 4%, 5%, 6%, 8%, 10%, 12%, 15%, 18% or 20%, preferably 5%-25%, more preferably 10%-20%.

[0012] Furthermore, the present invention also provides a method for preparing the above-mentioned bimetallic oxide catalyst, the method comprising the following steps:

[0013] (1) Dissolve zirconium salt and urea in water to form an aqueous solution;

[0014] (2) The aqueous solution is hydrothermally heated for 2-20 hours at 273-673K, preferably 413-473K, to achieve solid-liquid separation;

[0015] (3) The solid obtained after solid-liquid separation is dried in air at 373-973K, preferably 373-573K, to obtain monoclinic zirconia precursor;

[0016] (4) Mix the M salt solution with the monoclinic zirconium oxide precursor, dry and calcine;

[0017] or

[0018] (1) Dissolve zirconium salt and urea in alcohol to form an alcohol solution;

[0019] (2) The solution is hydrothermally heated at 273-673K, preferably 413-473K, for 2-20 hours to separate the solid and liquid;

[0020] (3) The solid obtained after solid-liquid separation is dried in an inert atmosphere such as nitrogen, helium and argon at 373-973K, preferably 373-573K, to obtain tetragonal zirconia precursor.

[0021] (4) Mix the M salt solution with the tetragonal zirconia precursor, dry and calcine.

[0022] According to some embodiments of the present invention, the zirconium content in the aqueous or alcoholic solution is 0.01-10 mol / L, preferably 0.2-0.6 mol / L.

[0023] According to some embodiments of the present invention, the mixing temperature is 288–313 K and the mixing time is 12–36 h.

[0024] According to some embodiments of the present invention, the calcination temperature is 373-973K, preferably 773-873K.

[0025] According to some embodiments of the present invention, the zirconium salt used is one or more of zirconium nitrate, zirconium n-butoxide, zirconium oxychloride, and zirconium oxynitrate; the M salt is selected from gallium salt, indium salt, and zinc salt.

[0026] Preferably, the gallium salt used is one or more of gallium nitrate, gallium chloride, gallium acetate, and gallium sulfate.

[0027] Preferably, the indium salt used is one or more of indium nitrate, indium chloride, indium acetate, and indium sulfate.

[0028] Preferably, the zinc salt used is one or more of zinc nitrate, zinc chloride, zinc acetate, and zinc sulfate;

[0029] Preferably, the molar ratio of urea to metal ions (i.e., M ions) is between 1 and 20.

[0030] Preferably, the alcohol used is one or more of C1-C10 alcohols.

[0031] This invention develops a method for preparing bimetallic oxide catalysts using monoclinic zirconium oxide or tetragonal zirconium oxide as supports, and the prepared MO... x / m-ZrO2 and MO x The / t-ZrO2 (where M = Ga) catalyst can be used for the hydrogenation of carbon dioxide to methanol and dimethyl ether. Under the same conditions, it exhibits superior activity compared to catalysts prepared by the traditional co-precipitation method, and the product distributions of the Ga2O3 / m-ZrO2 and Ga2O3 / t-ZrO2 catalysts differ. Furthermore, the catalyst prepared by the method of this invention also possesses characteristics such as anti-sintering and good stability.

[0032] The catalyst obtained by the preparation method described in this invention can effectively convert carbon dioxide into methanol and dimethyl ether, with an optimal reaction temperature of 603-623 K. It exhibits good resistance to sintering and stability. (The last sentence appears to be incomplete and possibly refers to a specific reaction process: "At 3 MPa, 603 K, 24000 mL / (g..."). cat Under the conditions of ·h), the single-pass CO2 conversion on the Ga2O3 / t-ZrO2 catalyst was 10.0%, and the selectivity for methanol and dimethyl ether reached 73.2%, with a space-time yield of 0.66 g for methanol and dimethyl ether. (methanol+DME) / (g cat ·h). Attached Figure Description

[0033] Figure 1 It is m-ZrO2, t-ZrO2, MO x / m-ZrO2 and MO x Powder X-ray diffraction pattern of / t-ZrO2 (where M = Ga, In and Zn) catalyst.

[0034] Figure 2 The catalytic performance of Ga2O3 / m-ZrO2 (m-: monoclinic) and Ga2O3 / t-ZrO2 (t-: tetragonal) was demonstrated under the following reaction conditions: T = 513-653 K; P = 3 MPa; H2 / CO2 = 3 / 1; GHSV = 24,000 mL / (g) cat h).

[0035] Figure 3 The product selectivity of Ga2O3 / m-ZrO2 (m-: monoclinic) and Ga2O3 / t-ZrO2 (t-: tetragonal) catalysts was compared under the following reaction conditions: T = 613 K; P = 3 MPa; H2 / CO2 = 3 / 1; GHSV = 24,000 mL / (g) cat h).

[0036] Figure 4 The 100-h long-term stability test results of the Ga2O3 / m-ZrO2 (m-: monoclinic) catalyst are presented under the following reaction conditions: T = 603 K; P = 3 MPa; H2 / CO2 = 3 / 1; GHSV = 24,000 mL / (g) cat h). Detailed Implementation

[0037] The present invention will now be further described in conjunction with the following embodiments, which are intended to further illustrate the present invention and do not limit the scope of the pending claims in any way.

[0038] The preparation method of bimetallic oxide catalysts supported by monoclinic zirconium oxide or tetragonal zirconium oxide for the hydrogenation of carbon dioxide to methanol and dimethyl ether firstly involves synthesizing monoclinic (m-)ZrO2 or tetragonal (t-)ZrO2 precursors, respectively. Precursors of m-ZrO2 and t-ZrO2 were synthesized by hydrothermal and alcoholic methods, with zirconium concentrations ranging from 0.01 to 10 mol / L. A certain amount of urea was added as a precipitant, followed by a certain volume of ultrapure water or alcohol. The mixture was hydrothermally heated at 373-473 K for 10-20 h, filtered / washed by centrifugation, and dried / calcined under vacuum / air / nitrogen atmosphere to obtain the precursors. Then, a certain amount of aqueous and / or alcoholic solution of metal salts (Ga, In, and Zn) was added to the precursors, with a metal salt loading of 0.1%-80%. The mixture was stirred at room temperature for 12-36 h, dried, and then further dried at 373-423 K and calcined at 573-873 K to obtain MO. x / m-ZrO2 and MO x / t-ZrO2 (where M = Ga, In and Zn) catalyst.

[0039] Furthermore, the zirconium salt used is one or more of zirconium nitrate, zirconium n-butoxide, zirconium oxychloride, and zirconium oxynitrate. The gallium salt used is one or more of gallium nitrate, gallium chloride, acetate, and sulfate. The indium salt used is one or more of indium nitrate, indium chloride, indium acetate, and indium sulfate. The zinc salt used is one or more of zinc nitrate, zinc chloride, zinc acetate, and zinc sulfate. The ratio of urea to metal ions is between 1 and 20. The alcohols used are C1–C2. 10 One or more of the alcohols.

[0040] Furthermore, the calcination atmosphere is one or more of air, nitrogen, helium, and argon.

[0041] The obtained bimetallic oxide catalysts with different crystal forms were all solid solution structures, characterized by metal M (M = Ga, In, and Zn) incorporated into the ZrO2 lattice. The structural features are shown in [reference needed]. Figure 1 .

[0042] Meanwhile, the present invention also provides a MO obtained by the above preparation method. x / m-ZrO2 and MO x The / t-ZrO2 (where M = Ga) catalyst can be used to catalyze the hydrogenation of carbon dioxide to produce methanol and dimethyl ether. The application steps are as follows:

[0043] The catalytic activity evaluation for the hydrogenation of carbon dioxide to methanol and dimethyl ether was conducted in a micro-fixed-bed continuous flow reactor and an online gas chromatography system. Before the reaction, the catalyst was activated with one or two of hydrogen, argon, and nitrogen at 473–673 K for 1–12 h. The conditions for the synthesis of methanol and dimethyl ether by carbon dioxide hydrogenation were: feed gas pressure 0.1–20 MPa, reaction temperature 513–673 K, and space velocity 6000–40000 mL / (g) cat •h), V(H2) / V(CO2)=1-30. Online gas chromatography equipped with a thermal conductivity detector (TCD) and a flame ionization detector (FID) was used to separate and identify the reaction products. A capillary column (Agilent HP-Plot Q, 30m × 0.53mm × 40μm) connected to the FID was used to analyze hydrocarbons, alcohols, and other carbon-containing products. A packed column (Lanzhou Donglilong Information Technology Co., Ltd., TDX-01, 2m × 3mm) connected to the TCD was used to analyze other gaseous products (Ar, CO, CH4, and CO2). The pipeline between the reactor and valves was heated to 373-433K to prevent product condensation. CH4 was used as a bridge between the FID and TCD for quantitative analysis of the products.

[0044] Example 1

[0045] 4.6 g of ZrO(NO3)2 was weighed into a 100 mL beaker, then 12 g of urea was weighed and added to 50 mL of water. The mixture was stirred until the solid dissolved. The solution was transferred to a 100 mL hydrothermal reactor and heated at 433 K for 20 h. After cooling to room temperature, the solution was centrifuged, washed, and dried. The solid was dried overnight at 383 K (the dried solid was the m-ZrO2 precursor) and calcined in flowing air at 673 K. The resulting catalyst was labeled as m-ZrO2. The catalyst was pressed into tablets, sieved, and catalyst particles with a particle size of 230–400 μm were obtained for catalytic evaluation.

[0046] Mix 0.3g of sieved catalyst and 0.7g of quartz sand thoroughly, place in a fixed-bed reactor under constant temperature, and fix with glass wool at the top and bottom. Pretreat with H2 (30ml / min, atmospheric pressure) for 2h at 613K, then cool to the reaction temperature. A mixed gas with a flow rate of V(H2) / V(CO2) / V(Ar) = 72 / 24 / 4 is introduced into the reaction tube via a mass flow meter. Reaction conditions: T = 613K, P = 3MPa, GHSV = 24,000mL / (g) cat h). The catalytic evaluation results are shown in Table 1.

[0047] Example 2

[0048] Weigh 4.6 g of ZrO(NO3)2 into a 100 mL beaker, then weigh 12 g of urea and add 50 mL of methanol, stirring until the solid dissolves. Transfer the solution to a 100 mL hydrothermal reactor and heat at 433 K for 20 h. After cooling to room temperature, centrifuge, wash, and dry. Dry overnight at 383 K (the dried solid is the t-ZrO2 precursor), and calcine in flowing air at 673 K. The resulting catalyst is labeled as t-ZrO2. The catalyst evaluation procedure and reaction conditions are the same as in Example 1, and the catalytic evaluation results are shown in Table 1.

[0049] Example 3

[0050] A certain amount of Ga(NO3)3·9H2O was weighed and placed in a muffle furnace and calcined at 773K. The resulting catalyst was labeled as Ga2O3. The catalyst evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0051] Example 4

[0052] 1.0 g of the m-ZrO2 precursor from Example 1 was weighed and placed in a round-bottom flask. The flask was evacuated for 2 hours. 0.1784 g of Ga(NO3)3·9H2O was dissolved in 6 mL of methanol solution and added to the m-ZrO2 precursor. The mixture was stirred at room temperature for 24 hours, rotary evaporated, dried at 383 K overnight, and then calcined at 673 K for 4 hours. The resulting catalyst was labeled as Ga2O3 / m-ZrO2-5% (m-: monoclinic). The catalyst evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0053] Example 5

[0054] The m-ZrO2 precursor from Example 1 was weighed out. The catalyst preparation method was the same as in Example 4, except that 0.3767 g of Ga(NO3)3·9H2O was added. The resulting catalyst was labeled as Ga2O3 / m-ZrO2-10%. The evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0055] Example 6

[0056] The m-ZrO2 precursor from Example 1 was weighed out. The catalyst preparation method was the same as in Example 4, except that 0.5982 g of Ga(NO3)3·9H2O was added. The resulting catalyst was labeled as Ga2O3 / m-ZrO2-15%. The evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0057] Example 7

[0058] The m-ZrO2 precursor from Example 1 was weighed out. The catalyst preparation method was the same as in Example 4, except that 0.8474 g of Ga(NO3)3·9H2O was added. The resulting catalyst was labeled as Ga2O3 / m-ZrO2-20%. The evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0059] Example 8

[0060] 1.0 g of the t-ZrO2 precursor from Example 2 was weighed and placed in a round-bottom flask. The flask was evacuated for 2 hours. 0.1784 g of Ga(NO3)3·9H2O was dissolved in 6 mL of methanol solution and added to the t-ZrO2 precursor. The mixture was stirred at room temperature for 24 hours, rotary evaporated, dried at 383 K overnight, and then calcined at 823 K for 4 hours. The resulting catalyst was labeled as Ga2O3 / t-ZrO2-5% (t-: tetragonal). The catalyst evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0061] Example 9

[0062] The t-ZrO2 precursor from Example 2 was weighed out. The catalyst preparation method was the same as in Example 4, except that 0.3767 g of Ga(NO3)3·9H2O was added. The resulting catalyst was labeled as Ga2O3 / t-ZrO2-10%. The evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0063] Example 10

[0064] The t-ZrO2 precursor from Example 2 was weighed out. The catalyst preparation method was the same as in Example 4, except that 0.5982 g of Ga(NO3)3·9H2O was added. The resulting catalyst was labeled as Ga2O3 / t-ZrO2-15%. The evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0065] Example 11

[0066] The t-ZrO2 precursor from Example 2 was weighed out. The catalyst preparation method was the same as in Example 4, except that 0.8474 g of Ga(NO3)3·9H2O was added. The resulting catalyst was labeled as Ga2O3 / t-ZrO2-20%. The evaluation steps and reaction conditions were the same as in Example 1. The catalytic evaluation results are shown in Table 1.

[0067] Example 12

[0068] The catalysts of Examples 1 and 2 were prepared according to n Ga / (n Ga +n Zr The catalyst was physically mixed in a ratio of 0.1 (Ga₂O₃ + ZrO₂) and labeled as Ga₂O₃ + ZrO₂. The evaluation steps and reaction conditions were the same as in Example 1, and the catalytic evaluation results are shown in Table 1.

[0069] Example 13

[0070] 4.1621 g of ZrO(NO3)2 and 0.8354 g of Ga(NO3)3·9H2O were weighed and dissolved in 100 mL of deionized water, and stirred vigorously at 343 K. 3.06 g of (NH4)2CO3 was weighed and dissolved in 100 mL of deionized water, then added to the above solution (3 mL / min) until a precipitate formed. The solution was then aged at 343 K for 2 h, cooled to room temperature, filtered, washed, and dried at 383 K for 4 h. Finally, it was calcined at 773 K for 3 h under flowing air (heating at 1 K / min). The resulting catalyst was labeled as Ga2O3-ZrO2 (coprecipitate). The evaluation procedures and reaction conditions were the same as in Example 1, and the catalytic evaluation results are shown in Table 1.

[0071] Table 1. Catalytic evaluation results of Ga2O3 supported on different crystal forms of ZrO2 and prepared by different methods. Reaction conditions: T = 613 K; P = 3 MPa; GHSV = 24,000 mL / (g cat h); H2 / CO2 = 3 / 1.

[0072]

[0073] Table 1 shows that the pure Ga₂O₃ catalyst exhibits slightly higher activity for methanol and dimethyl ether synthesis than the pure ZrO₂ catalyst, while the catalytic performance of monoclinic zirconium oxide and tetragonal zirconium oxide alone is similar. For catalysts with a Ga content below 20%, Ga₂O₃ / t-ZrO₂ shows higher yields of methanol and dimethyl ether than Ga₂O₃ / m-ZrO₂, demonstrating superior catalytic performance. Compared to single oxides and physically mixed bimetallic oxides, the Ga₂O₃ / m-ZrO₂ and Ga₂O₃ / t-ZrO₂ prepared by this method show better catalytic performance, indicating a strong synergistic effect between Ga and Zr. Compared to catalysts prepared by the co-precipitation method, the Ga₂O₃ / ZrO₂ catalyst prepared by this method exhibits better activity for CO₂ hydrogenation to methanol and dimethyl ether under the same conditions.

Claims

1. A double metal oxide catalyst comprising a zirconia support and a metal M selected from Ga, the metal M being incorporated into the zirconia support lattice, the zirconia support being a single crystalline form tetragonal zirconia; On an atomic percentage basis, (M / (M+Zr)) is 10%-20%; the preparation method of the bimetallic oxide catalyst includes the following steps: (1) Dissolve zirconium salt and urea in an alcohol solution; (2) Heat the solution at 273-673 K for 2-20 h to separate the solid and liquid; (3) The solid obtained after solid-liquid separation is dried under an inert atmosphere at 373-573 K to obtain tetragonal zirconia precursor; (4) Mix the M salt solution with the tetragonal zirconia precursor, dry and calcine.

2. The catalyst of claim 1, wherein In step (1), the zirconium content in the alcohol solution is 0.01-10 mol / L.

3. The catalyst according to claim 1, characterized in that, In step (1), the zirconium content in the alcohol solution is 0.1-0.6 mol / L.

4. The catalyst according to claim 1, characterized in that, In step (4), the mixing temperature is 288-313 K, the mixing time is 12-36 h, and the calcination temperature is 373-973 K.

5. The catalyst according to claim 1, characterized in that, The zirconium salt used is one or more of zirconium nitrate, zirconium oxychloride, and zirconium oxynitrate; M salt is selected from gallium salt.

6. The catalyst according to claim 5, characterized in that, The gallium salt used is one or more of gallium nitrate, gallium chloride, gallium acetate, and gallium sulfate.

7. The catalyst according to claim 1, characterized in that, The molar ratio of urea to metal M ions is between 1 and 20.

8. The catalyst according to claim 1, characterized in that, The alcohol used is one or more of the C1-C10 alcohols.

9. The use of the bimetallic oxide catalyst according to any one of claims 1-8 in the hydrogenation of carbon dioxide to prepare methanol and dimethyl ether.

10. The application as described in claim 9, characterized in that, The reaction of carbon dioxide hydrogenation to synthesize methanol and dimethyl ether is carried out in a pressurized fixed-bed flow reactor under the following reaction conditions: P = 1-20 MPa; T =513-673 K; air velocity is 6000-40000 ml / (g) cat •h); Gas molar ratio H2 / CO2 = 1-10.

11. The application as described in claim 9 or 10, characterized in that, The catalyst is activated before application under the following conditions: hydrogen and one or two of argon, carbon dioxide, helium, and nitrogen are activated at 473-673 K for 1-12 h.

12. The application as described in claim 9 or 10, characterized in that, The obtained catalyst was tableted, and samples with a particle size of 180-360 μm were screened for evaluation.

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