Reverse catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalyst preparation, and particularly relates to a reverse catalyst as well as a preparation method and application thereof. The reverse catalyst contains a Cu simple substance and ZrO2 loaded on the Cu simple substance, wherein the reverse catalyst is nanoparticles with a core-shell structure, copper is taken as a core, and zirconium oxide is taken as a shell. The ZrO2 / Cu reverse catalyst has high activity and stability in the process of preparing methanol from CO2, can be used for a reaction of preparing methanol from CO2 through hydrogenation at low temperature and high efficiency, and greatly improves the anti-sintering performance of a Cu-based catalyst. According to the technical scheme, a coprecipitation method is adopted, metal copper salt and zirconium salt serve as precursor salt, precipitation is conducted in an organic solvent through an acid precipitator, the preparation steps are simple, the reverse ZrO2 / Cu catalyst can be prepared, the size of two phases can be conveniently adjusted, and the catalyst with the new morphology and improved performance is obtained.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, and specifically relates to a reversed-phase catalyst, its preparation method, and its application. Background Technology

[0003] Catalysts for the thermal catalytic production of methanol from carbon dioxide hydrogenation mainly include metal catalysts, represented by Cu-based catalysts, and oxide catalysts. Oxide catalysts have the advantage of high methanol selectivity, but suffer from relatively high operating temperatures (280-350℃) and poor hydrogen activation ability. Cu-based catalysts are widely used due to their high activity and low cost, but they are prone to sintering and deactivation. In recent years, research has found that the anti-sintering performance and activity of Cu-based catalysts can be significantly enhanced by creatively preparing reverse-phase catalysts. CN114345353B prepared a core-shell catalyst using hollow copper-zinc oxide spheres as the metal framework via a sol-assisted method; CN117019160A synthesized hollow layered copper silicate (CuSiO-3) using a hydrothermal method, and then prepared a reverse-phase xZnO / CuSiO-3 catalyst by depositing a ZnO film on the CuSiO-3 surface using atomic layer deposition technology, which showed a significant improvement in performance during the CO2 hydrogenation to methanol reaction. Chemical Engineering Journal 470(2023)144006: The normal and reverse phases of Cu / ZrO2 catalysts were achieved using a stepwise precipitation method with oxalic acid. Under reaction conditions of 220℃, the reverse phase catalyst showed significantly better activity than the normal phase. Applied Catalysis B: Environmental 334(2023)122839: In the methanol steam reforming reaction, the optimal ratio of the reverse phase ZrO2 / Cu catalyst was ZrO2-0.1 / Cu, with a 100% selectivity. Nature Communications 11(2020)5767: The ZrO2 / Cu catalyst prepared by the reverse addition method exhibited a distinct core-shell structure, with ZrO2 primarily in a highly reduced state. However, the above reverse phase Cu-based catalysts are prone to sintering at operating temperatures, and their size is difficult to adjust; therefore, the activity of the CO2 hydrogenation to methanol catalyst needs further improvement. Summary of the Invention

[0004] The technical problem to be solved by this invention is to address the issues of easy sintering of Cu-based catalysts, difficulty in adjusting the size of reversed Cu-based catalysts, and low activity of CO2 hydrogenation to methanol catalysts in the prior art. This invention provides a ZrO2 / Cu reversed catalyst, its preparation method, and its application. This ZrO2 / Cu reversed catalyst exhibits high activity and stability in the CO2 to methanol process, can be used as a low-temperature, high-efficiency catalyst for the CO2 hydrogenation to methanol reaction, and significantly improves the anti-sintering performance of Cu-based catalysts.

[0005] The first aspect of the present invention is to provide a reverse catalyst containing elemental Cu and ZrO2 supported on elemental Cu; wherein the reverse catalyst is a core-shell structured nanoparticle with a copper core and a zirconium oxide shell.

[0006] The ZrO2 / Cu reverse catalyst of this invention can be used as a low-temperature and high-efficiency catalyst for the hydrogenation of CO2 to methanol, and it significantly improves the anti-sintering performance of Cu-based catalysts.

[0007] According to some preferred embodiments of the present invention, the molar ratio of Cu to Zr in the reverse catalyst is (6-10):1, based on the molar amounts of copper and zirconium respectively.

[0008] According to some preferred embodiments of the present invention, the average particle size of the reversed catalyst is 20-60 nm;

[0009] More preferably, the average particle size of Cu in the reverse catalyst is 10-50 nm, preferably 10-30 nm; and / or, the average particle size of ZrO2 is 0.4-10 nm, preferably 0.4-2 nm.

[0010] The particle sizes of the two phases can be determined by XRD and TEM.

[0011] A second aspect of the present invention is to provide a method for preparing a reversed-phase catalyst, preferably used in the method for preparing the reversed-phase catalyst described in the first aspect, comprising:

[0012] Solution 1 containing copper and zirconium precursors and solution 2 containing precipitant are brought into contact by forward or reverse dropwise addition and reacted under mixed conditions to obtain the precipitate of intermediate product.

[0013] The precipitate of the intermediate product is optionally dried, then calcined, and then Cu is reduced in a mixed atmosphere of hydrogen and protective gas to obtain the reverse catalyst.

[0014] According to the present invention, the mixing method in the reaction under mixed conditions includes, but is not limited to, stirring. The temperature of the reaction under mixed conditions is not particularly limited by the present invention, but is preferably room temperature (5-30°C), for example, room temperature (25°C). The mixing and stirring time is also not particularly limited by the present invention, and can be, for example, 0.5-2 hours.

[0015] The technical solution adopted in this invention is to use a co-precipitation method, using copper salt and zirconium salt as precursor salts, and precipitating them in an organic solvent with an acid precipitant.

[0016] According to some preferred embodiments of the present invention, the copper precursor is a copper salt, preferably copper acetate and / or copper nitrate.

[0017] According to some preferred embodiments of the present invention, the zirconium precursor is a zirconium salt, preferably zirconium acetate and / or zirconium nitrate.

[0018] According to some preferred embodiments of the present invention, the solvents used in the first solution and the second solution may be the same or different, and are independently selected from one or more of ethanol, water, n-propanol, isopropanol, acetonitrile, acetone, tetrahydrofuran, 1,4-dioxane, and N'N-dimethylformamide, preferably one or more of acetonitrile, n-propanol, and ethanol.

[0019] According to some preferred embodiments of the present invention, the precipitant is selected from acid precipitants, preferably one or more of oxalic acid, citric acid, glycine, and ammonium carbonate, and more preferably one or more of oxalic acid, citric acid, and glycine.

[0020] When the solvent is water, the precipitant is not ammonium carbonate.

[0021] According to some preferred embodiments of the present invention, the molar ratio of copper precursor to zirconium precursor is (6-10):1, based on the molar amounts of copper and zirconium.

[0022] According to some preferred embodiments of the present invention, the concentration of the copper precursor in the first solution is 0.05-2 mol / L.

[0023] According to some preferred embodiments of the present invention, the concentration of the precipitant in the second solution is 0.1-3 mol / L.

[0024] According to some preferred embodiments of the present invention, the amounts of solution one and solution two are such that the molar ratio of the precipitant to the total amount of the copper precursor and zirconium precursor is (0.5-3):1.

[0025] According to some preferred embodiments of the present invention, the rates of forward and reverse dripping are each 1-5 ml / min.

[0026] According to some preferred embodiments of the present invention, solution two is added dropwise to solution one.

[0027] According to some preferred embodiments of the present invention, the calcination conditions include: a calcination temperature of 300-600°C and / or a calcination time of 2-6 hours; preferably, the temperature is increased to the calcination temperature at a heating rate of (1-5)°C / min, and then calcined for 2-6 hours.

[0028] According to some preferred embodiments of the present invention, the protective gas is nitrogen and / or an inert gas. The volume ratio of hydrogen in the mixed atmosphere of hydrogen and the protective gas varies widely, including but not limited to the conditions in the embodiments.

[0029] According to some preferred embodiments of the present invention, the conditions for reducing Cu include: a temperature of 200-400°C and / or a time of 1-3 hours.

[0030] The catalyst involved in this invention has a simple preparation step, and exhibits stable operation for 200 hours in the low-temperature, high-efficiency catalytic hydrogenation of CO2 to methanol. The catalyst remains stable after the reaction, without sintering. This solves the problem of Cu-based catalysts being prone to sintering in this reaction.

[0031] This invention provides a catalyst for methanol production and a method for preparing the same, which can be applied to industrial methanol production technology.

[0032] A third aspect of the present invention is to provide the application of the reversed-phase catalyst described in the first aspect or the reversed-phase catalyst obtained by the preparation method described in the second aspect in a catalytic hydrogenation reaction, preferably in the hydrogenation of carbon dioxide to methanol.

[0033] As an example, the catalyst is reduced at 250℃-350℃ for 2 hours in a hydrogen-argon atmosphere, and then cooled to 150℃-250℃. The catalyst is then subjected to CO2 hydrogenation to methanol reaction under 2-5 MPa conditions. The catalyst can operate stably for 200 hours with virtually no performance degradation.

[0034] The present invention provides a method for producing methanol by hydrogenation of carbon dioxide, comprising contacting carbon dioxide and hydrogen in the presence of a catalyst to carry out a hydrogenation reaction to obtain methanol;

[0035] The catalyst is the reversed-phase catalyst described in the first aspect or the reversed-phase catalyst obtained by the preparation method described in the second aspect.

[0036] According to some preferred embodiments of the present invention, the conditions for the hydrogenation reaction include:

[0037] The temperature is 150-250℃, and / or the pressure is 2-5 MPa, with a volume ratio of carbon dioxide to hydrogen of 1:(2-10); and / or the volume hourly space velocity of carbon dioxide and hydrogen is 6000-96000 h⁻¹. -1 .

[0038] As an example, the method for producing methanol by carbon dioxide hydrogenation is carried out in a fixed-bed reactor under high pressure (2-5 MPa), and the specific steps include:

[0039] Weigh 0.05-1.5 g of the ZrO2 / Cu reversed-phase catalyst, mix it evenly with the diluent, and then load it into the fixed-bed isothermal section. After confirming that the reactor is leak-proof, raise the temperature to 250-350℃ in an H2 / Ar atmosphere for 2 hours for reduction, then lower the temperature to 150-250℃ and switch to the reaction gas H2 / CO2, and pressurize it to 2-5 MPa.

[0040] The catalyst of this invention can efficiently catalyze the hydrogenation of CO2 to methanol at a relatively low temperature of 150-250℃; after a 200-hour stability test at 150-250℃ and 2-5MPa, the resulting catalyst showed no deactivation or sintering.

[0041] Compared with the prior art, the advantages of the present invention are:

[0042] The ZrO2 / Cu reversed-phase catalyst exhibits high activity and stability in the CO2-to-methanol process, serving as a high-efficiency catalyst for the low-temperature CO2 hydrogenation to methanol reaction, and significantly improving the anti-sintering performance of Cu-based catalysts. It demonstrates excellent low-temperature performance and high selectivity for the target product in CO2 hydrogenation to methanol.

[0043] This invention innovatively proposes a method to obtain a nanoscale reverse catalyst with a core-shell structure through co-precipitation. Preferably, the core size can be adjusted by adjusting the preparation parameters. The catalyst of this invention has high activity and stability, and improves the anti-sintering performance of Cu. In particular, the optimal catalyst has significantly improved activity and stability in the CO2 to methanol process, and improves the anti-sintering performance of Cu.

[0044] This invention can obtain core-shell structured reversed-phase catalysts of Cu with different sizes; the catalyst can operate stably for a long period of time at a reaction temperature of 150-250℃ and a pressure of 2-5MPa, and there is no obvious deactivation (no sintering phenomenon) during the reaction, which solves the problem that Cu-based catalysts are prone to sintering in this reaction.

[0045] The catalyst and its preparation method provided by this invention have simple preparation steps, which can not only prepare reverse ZrO2 / Cu catalysts, but also facilitate the adjustment of the size of the two phases to obtain catalysts with new morphologies and improved performance. Attached Figure Description

[0046] Figure 1 XRD patterns of the methanol production catalyst 90ZrO2 / Cu of the present invention (Examples 1-5);

[0047] Figure 2(a) TEM image of the methanol production catalyst 90ZrO2 / Cu in Example 1 of the present invention;

[0048] Figure 2(b) EDS spectrum of the methanol production catalyst 90ZrO2 / Cu in Example 1 of the present invention;

[0049] Figure 3 The TOS of the methanol production catalyst 90ZrO2 / Cu in Example 1 of this invention.

[0050] Depend on Figure 1 It is evident that catalysts prepared with different solvents exhibit diffraction peaks of metallic Cu with varying intensities, corresponding to different Cu particle sizes.

[0051] As can be seen from Figures 2(a) and 2(b), the reversed catalyst has a core-shell structure with copper as the core and co-precipitated zirconium oxide as the shell. The zirconium oxide uniformly coats the copper particles. The formation of the core-shell structure can be seen in the figures, and the size of the Cu particles in the middle (the darker part in the circle in Figure 2(a)) is about 20 nm. The average particle size of the 90ZrO2 / Cu reversed catalyst is about 20.8 nm; and the average particle size of ZrO2 is in the range of 0.4-2 nm.

[0052] It was verified that the morphology of the catalysts obtained in Examples 2 and 6-11 was similar to that of the catalyst in Example 1. The average particle size of Cu elemental was 10-30 nm, and the average particle size of the 90ZrO2 / Cu reverse catalyst was 20-60 nm.

[0053] Depend on Figure 3 It is evident that this catalyst can operate stably for an extended period of time. Detailed Implementation

[0054] The present invention will now be described in detail with reference to specific embodiments. It should be noted that the following embodiments are only used to further illustrate the present invention and should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the content of the present invention are still within the scope of protection of the present invention.

[0055] Example 1

[0056] 1. Catalyst preparation:

[0057] Weigh 3.2616 g of copper nitrate (0.017 mol) and 0.6440 g of zirconium nitrate (0.0019 mol), dissolve them in 150 ml of acetonitrile, stir to dissolve, and obtain a metal salt solution, which is solution one;

[0058] Weigh 2.2920 g (0.025 mol) of oxalic acid, dissolve it in 50 ml of acetonitrile, stir to dissolve, and obtain an oxalic acid solution, which is solution two;

[0059] Oxalic acid solution was added dropwise to metal salt solution at a rate of 2.5 ml / min, stirred for 1 hour (at room temperature), and then filtered to obtain the precipitate of intermediate product.

[0060] The intermediate product precipitate was dried and then calcined: the temperature was increased to 400℃ at a rate of 1℃ / min, and calcined in a muffle furnace and held at 400℃ for 4h to obtain oxides.

[0061] The obtained oxide was reduced in a tube furnace with a hydrogen-argon mixture (volume ratio of hydrogen to argon was 5% H2 / Ar) for 2 h at 300 °C to obtain a ZrO2 / Cu reverse-phase catalyst.

[0062] The crystal phase of the catalyst was characterized by XRD. Figure 1 The catalyst structure was characterized by EDS (Figure 2(b)).

[0063] 2. Methods for producing methanol by hydrogenation of carbon dioxide (i.e., methods for evaluating catalysts):

[0064] The catalyst was pressed into sheets using a mold, then filtered and granulated using a sieve. After being heated to 200°C in a hydrogen atmosphere, the pressure was switched to CO2 + H2 and increased to 5 MPa for the reaction. The volume ratio of carbon dioxide to hydrogen in CO2 + H2 was 1:4; the volume hourly space velocity (VHSV) of CO2 + H2 was 48000 ml / g. cat / h.

[0065] The activity evaluation results of the catalyst are shown in Figure 3 As can be seen from the figure, the catalyst has stable performance, and its activity did not decrease after 200 hours of reaction.

[0066] Example 2

[0067] The catalyst synthesis steps were followed as described in Example 1, except that the solvents in solutions one and two were changed, with n-propanol being used instead. XRD characterization results are shown below. Figure 1 The catalyst was evaluated using the same method as in Example 1, and the catalytic reaction results are shown in Table 1.

[0068] Example 3

[0069] The catalyst synthesis steps were followed as described in Example 1, except that the solvents in Solutions 1 and 2 were changed, with water being used instead. XRD characterization results are shown below. Figure 1 The catalyst was evaluated using the same method as in Example 1, and the catalytic reaction results are shown in Table 1.

[0070] Example 4

[0071] The catalyst synthesis steps were followed as described in Example 1, except that the solvents in solutions one and two were changed, with tetrahydrofuran being used instead. XRD characterization results are shown below. Figure 1 The catalyst was evaluated using the same method as in Example 1, and the catalytic reaction results are shown in Table 1.

[0072] Example 5

[0073] The catalyst synthesis steps were followed as described in Example 1, except that the solvents in solutions one and two were changed, with 1,4-dioxane being substituted. XRD characterization results are shown below. Figure 1 The catalyst was evaluated using the same method as in Example 1, and the catalytic reaction results are shown in Table 1.

[0074] Example 6

[0075] Weigh 3.261 g of copper nitrate and 0.644 g of zirconium nitrate, dissolve them in 150 ml of acetonitrile, stir to dissolve, and obtain a metal salt solution;

[0076] Weigh 2.292 g of oxalic acid, dissolve it in 50 ml of acetonitrile, stir to dissolve, and obtain oxalic acid solution.

[0077] The metal salt solution was then added dropwise to the oxalic acid solution at a rate of 2.5 ml / min, and stirred for 1 hour. After filtration and drying, the solution was calcined: the temperature was increased to 400 °C at a rate of 1 °C / min, and calcined in a muffle furnace, held at 400 °C for 4 hours. The resulting oxide was then reduced in a tube furnace with a hydrogen-argon mixture (same as in Example 1) at 300 °C for 2 hours. The crystal phase of the catalyst was characterized by XRD, and the catalyst structure was characterized by EDS.

[0078] The catalyst was evaluated using the same method as in Example 1, and the catalytic reaction results are shown in Table 1.

[0079] Example 7

[0080] The catalyst reduction time was changed to 1 hour, while all other catalyst preparation parameters remained unchanged. The catalyst evaluation method was the same as in Example 1, and the catalytic performance of the CO2 hydrogenation to methanol reaction was verified to be similar to that in Example 1.

[0081] Example 8

[0082] The catalyst reduction time was changed to 3 hours, while all other catalyst preparation parameters remained unchanged. The catalyst evaluation method was the same as in Example 1, and the catalytic performance of the CO2 hydrogenation to methanol reaction was verified to be similar to that in Example 1.

[0083] Example 9

[0084] The catalyst was prepared according to the method of Example 1, except that the molar ratio of oxalic acid to metal precursor salt was 1.5 (the amount of metal precursor salt remained unchanged), while other catalyst preparation parameters remained the same. The catalyst evaluation method was the same as in Example 1.

[0085] Example 10

[0086] The catalyst was prepared according to the method of Example 1, except that the dropping rate of the oxalic acid solution was changed to 5 ml / min, while all other catalyst preparation parameters remained unchanged. The catalyst evaluation method was the same as in Example 1.

[0087] Example 11

[0088] The catalyst was prepared according to the method of Example 1, except that the heating rate of catalyst calcination was changed to 5°C / min, while other catalyst preparation parameters remained unchanged. The catalyst evaluation method was the same as in Example 1.

[0089] Example 12

[0090] The catalyst synthesis steps described in Example 1 were followed, except that the precipitant was changed to ammonium carbonate. The catalyst evaluation method was the same as in Example 1, and the catalytic reaction results are shown in Table 1.

[0091] Example 13

[0092] The catalyst synthesis steps shown in Example 2 were followed, except that the precipitant was changed to ammonium carbonate. The catalyst evaluation method was the same as in Example 1, and the catalytic reaction results are shown in Table 1.

[0093] Comparative Example 1

[0094] The catalyst synthesis steps described in Example 3 were followed, except that the precipitant was changed to ammonium carbonate. The catalyst evaluation method was the same as in Example 1, and the catalytic reaction results are shown in Table 1.

[0095] Comparative Example 2

[0096] The catalyst synthesis steps are the same as in Example 2, except that, based on Example 1, Cu is precipitated first, and then Zr salt is added to precipitate Zr onto the Cu precipitate. Specifically:

[0097] Weigh 3.261 g of copper nitrate, dissolve it in 75 ml of acetonitrile, stir to dissolve, and obtain a metal salt solution, which is solution one;

[0098] Weigh 2.292g of oxalic acid, dissolve it in 50ml of acetonitrile, stir to dissolve, and obtain an oxalic acid solution, which is solution two;

[0099] Weigh 0.644 g of zirconium nitrate and dissolve it in 75 ml of acetonitrile. Stir to dissolve and obtain a metal salt solution, which is solution three.

[0100] Oxalic acid solution was added dropwise to solution one at a rate of 2.5 ml / min, followed by solution three. The mixture was stirred for 1 hour (at room temperature), and then filtered to obtain the precipitate of the intermediate product.

[0101] The intermediate product precipitate was dried and then calcined: the temperature was increased to 400℃ at a rate of 1℃ / min, and calcined in a muffle furnace and held at 400℃ for 4h to obtain oxides.

[0102] The obtained oxide was reduced in a tube furnace with a hydrogen-argon mixture (volume ratio of hydrogen to argon was 5% H2 / Ar) for 2 h at 300 °C to obtain the ZrO2 / Cu catalyst.

[0103] The catalyst was evaluated using the same method as in Example 1. It was verified that the ZrO2 / Cu catalyst in Comparative Example 2 performed poorly.

[0104] Table 1 shows the catalytic reaction results for each catalyst. Among them:

[0105] The CO2 conversion rate is calculated as follows: V out (v MeOH +v CO ) / V in v CO2 *100%;

[0106] The methanol selectivity is calculated as follows: = v MeOH / (v MeOH +v co ).

[0107] Vin is the feed volume, ml / min; v MeOH It is the volume fraction of the air outlet.

[0108] Table 1

[0109]

[0110] As can be seen from Examples 1-13 above, the catalyst of the present invention has significantly improved activity and stability in the CO2 to methanol process. In particular, in terms of catalytic stability, the stability is greatly improved compared with Comparative Example 1, achieving unexpected technical effects.

[0111] As can be seen from Examples 1, 2, and 6-11, the catalyst obtained under the preferred conditions of this invention achieves a CO2 conversion rate of over 10.5%, a methanol selectivity of over 89.5%, and a space-time yield of over 1.35 in the CO2-to-methanol process. After 200 hours of continuous reaction, the catalyst activity basically did not decrease, and it can operate stably for a long period of time. There is no obvious deactivation during the reaction process, and the overall performance is particularly excellent. Compared with Examples 3-5 using non-preferred solvents and Examples 12 and 13 using non-preferred precipitants, it has achieved unexpected technical effects.

[0112] The reason why the above-mentioned reversed catalyst of the present invention has the above advantages may be because the present invention has the morphology and size as analyzed in the accompanying drawings. The preparation method of the present invention yields the above-mentioned reversed catalyst with a specific core-shell structure. Preferably, the average particle size of the reversed catalyst is 20-60 nm; more preferably, the average particle size of Cu element in the reversed catalyst is 10-50 nm, preferably 10-30 nm.

[0113] In contrast, although document 1 also uses a reversed-phase catalyst, it has the largest core-shell interface. Therefore, its performance in the CO2-to-methanol process is significantly inferior to the catalyst in the embodiments of this invention. This may be because the precipitation of Cu and Zr in water using ammonium carbonate as a precipitant is too rapid.

[0114] As verified, the performance of the reversed catalyst in the embodiments of the present invention is significantly better than that of the catalyst in Comparative Example 2. This may be because, as mentioned above, the preparation method of the present invention makes it easier to adjust the size of the ZrO2 / Cu two phases. The catalyst in Comparative Example 2 is more of a simple supported catalyst, with zirconium oxide supported on copper, rather than a core-shell structure formed by zirconium oxide uniformly coating copper particles.

[0115] It should be noted that the embodiments described above are only for explaining the present invention and do not constitute any limitation on the present invention. The present invention has been described with reference to typical embodiments, but it should be understood that the words used therein are descriptive and explanatory terms, not limiting terms. Modifications can be made to the present invention within the scope of the claims, and revisions can be made to the present invention without departing from the scope and spirit of the present invention. Although the present invention described herein relates to specific methods, materials, and embodiments, it does not mean that the present invention is limited to the specific examples disclosed herein; on the contrary, the present invention can be extended to all other methods and applications with the same function.

[0116] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0117] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0118] The endpoints and any values ​​of the ranges disclosed in this application are not limited to the precise ranges or values; such ranges or values ​​should be understood to include values ​​close to them. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein. In principle, various technical solutions can be combined with each other to obtain new technical solutions, which should also be considered as specifically disclosed herein.

[0119] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

[0120] Furthermore, any implementation described herein can be freely combined with one or more other implementations described herein, and the resulting technical solutions or technical ideas shall be regarded as part of the original disclosure or original record of the present invention, and should not be regarded as new content not disclosed or anticipated herein, unless those skilled in the art consider the combination to be obviously unreasonable.

Claims

1. A reversed-phase catalyst comprising elemental Cu and ZrO2 supported on elemental Cu; wherein, The reverse catalyst is a core-shell structured nanoparticle with copper as the core and zirconium oxide as the shell.

2. The reversed catalyst according to claim 1, characterized in that: The molar ratio of Cu to Zr in the reverse catalyst is (6-10):1, based on the molar amounts of copper and zirconium.

3. The reversed-phase catalyst according to claim 1 or 2, characterized in that: The average particle size of the reversed-phase catalyst is 20-60 nm; Preferably, the average particle size of Cu in the reverse catalyst is 10-50 nm, more preferably 10-30 nm; and / or, the average particle size of ZrO2 is 0.4-10 nm, more preferably 0.4-2 nm.

4. A method for preparing a reversed-phase catalyst, preferably the method for preparing a reversed-phase catalyst according to any one of claims 1-3, comprising: Solution 1 containing copper and zirconium precursors and solution 2 containing precipitant are brought into contact by forward or reverse dropwise addition and reacted under mixed conditions to obtain the precipitate of intermediate product. The precipitate of the intermediate product is optionally dried, then calcined, and then Cu is reduced in a mixed atmosphere of hydrogen and protective gas to obtain the reverse catalyst.

5. The preparation method according to claim 4, characterized in that: The copper precursor is a copper salt, preferably copper acetate and / or copper nitrate; and / or The zirconium precursor is a zirconium salt, preferably zirconium acetate and / or zirconium nitrate; and / or The solvents used in Solution 1 and Solution 2 may be the same or different, and are independently selected from one or more of ethanol, water, n-propanol, isopropanol, acetonitrile, acetone, tetrahydrofuran, 1,4-dioxane, and N,N-dimethylformamide, preferably one or more of acetonitrile, n-propanol, and ethanol; and / or, The precipitant is selected from one or more of oxalic acid, citric acid, glycine, and ammonium carbonate, preferably one or more of oxalic acid, citric acid, and glycine.

6. The preparation method according to claim 3, characterized in that: The molar ratio of copper precursor to zirconium precursor is (6-10):1, based on the individual molar amounts of copper and zirconium; and / or, The concentration of the copper precursor in the first solution is 0.05-2 mol / L; and / or, The concentration of the precipitant in solution two is 0.1-3 mol / L; and / or, The amounts of solution one and solution two are used such that the molar ratio of the precipitant to the total amount of the copper precursor and zirconium precursor is (0.5-3):

1.

7. The preparation method according to any one of claims 4-6, characterized in that: The rates of forward and reverse dripping are each 1-5 ml / min; and / or, Add solution 2 dropwise into solution 1 in the forward direction; and / or, The calcination conditions include: a calcination temperature of 300-600℃, and / or a calcination time of 2-6 hours; preferably, the temperature is increased to the calcination temperature at a heating rate of (1-5)℃ / min, followed by calcination for 2-6 hours; and / or, The protective gas is nitrogen and / or an inert gas; and / or, The conditions for reducing Cu include a temperature of 200-400℃ and / or a time of 1-3 hours.

8. The application of a reversed catalyst according to any one of claims 1-3 or a reversed catalyst obtained by any one of claims 4-7 in a catalytic hydrogenation reaction, preferably in the hydrogenation of carbon dioxide to methanol.

9. A method for producing methanol by hydrogenation of carbon dioxide, comprising contacting carbon dioxide and hydrogen in the presence of a catalyst to carry out a hydrogenation reaction to obtain methanol; The catalyst is the reversed-phase catalyst according to any one of claims 1-3 or the reversed-phase catalyst obtained by the preparation method according to any one of claims 4-7.

10. The method according to claim 9, characterized in that: The conditions for the hydrogenation reaction include: The temperature is 150-250℃, and / or the pressure is 2-5 MPa, with a volume ratio of carbon dioxide to hydrogen of 1:(2-10); and / or the volume hourly space velocity of carbon dioxide and hydrogen is 6000-96000 h⁻¹. -1 .

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