Metal oxide and preparation method thereof, catalyst and application thereof, and method for preparing hydrocarbon compound through carbon dioxide hydrogenation

Abstract

The invention relates to the field of catalyst preparation, and discloses a metal oxide and a preparation method thereof, a catalyst and application thereof, and a method for preparing hydrocarbon compounds through carbon dioxide hydrogenation. The preparation method of the metal oxide comprises the following steps: (1) in the presence of a liquid medium, mixing a precursor of the metal oxide, a surfactant and a precipitator to obtain a mixed solution; (2) carrying out hydrothermal treatment on the mixed solution obtained in the step (1) to obtain a solid product; (3) roasting the solid product obtained in the step (2) to obtain a metal oxide; wherein the surfactant is selected from at least one of hexadecyl trimethyl ammonium halide, polyvinylpyrrolidone and lauryl sodium sulfate; the precipitant is urea. According to the metal oxide obtained by the method disclosed by the invention, the prepared catalyst has excellent catalytic performance. The catalyst is applied to a reaction for preparing hydrocarbon compounds through carbon dioxide hydrogenation, and the selectivity of target hydrocarbon products is high.

Description

Technical Field

[0001] The present invention relates to the field of catalyst preparation, and in particular to a metal oxide and a preparation method thereof, a catalyst and an application thereof, and a method for preparing hydrocarbon compounds by hydrogenating carbon dioxide. Background Art

[0002] Carbon dioxide emitted during industrial production is one of the main gases causing the greenhouse effect. With the emission of large amounts of carbon dioxide, the serious greenhouse effect leads to global warming. Therefore, reducing carbon emissions becomes particularly important. Based on the goal of carbon emission reduction, CCUS is currently the main way to reduce carbon dioxide emissions. Among them, using captured carbon dioxide as a carbon source to prepare chemicals is an important way to utilize carbon dioxide. Carbon dioxide molecules are highly symmetrical, have high bond energy, and are difficult to activate. The most common way is to convert carbon dioxide into methanol, formic acid, low-carbon olefins and C 5+ Chemicals such as hydrocarbons.

[0003] The production of hydrocarbons from carbon dioxide can be roughly divided into two routes. One is to use iron-based, cobalt-based and other catalysts of Fischer-Tropsch synthesis to convert carbon dioxide into carbon monoxide through reverse water gas shift, and then produce hydrocarbons through Fischer-Tropsch synthesis. This technical route couples the reverse water gas shift reaction and Fischer-Tropsch synthesis, so the product distribution is limited by the product distribution law of Fischer-Tropsch synthesis (Anderson-Schultz-Flory, ASF). The other route is to hydrogenate carbon dioxide through oxygen-containing compounds such as methanol, and then produce hydrocarbons through methanol to hydrocarbons (MTH) reaction on acidic molecular sieves. This route can obtain higher hydrocarbon selectivity. However, since the reaction temperature required for hydrogenation of carbon dioxide to produce methanol is generally lower than the MTH reaction temperature, low-carbon olefins and C 5+ The yield of target hydrocarbons such as hydrocarbons is low. Summary of the invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide a metal oxide and a preparation method thereof, a catalyst and an application thereof, and a method for preparing hydrocarbon compounds by hydrogenating carbon dioxide. The metal oxide obtained by the method of the present invention enables the prepared catalyst to have excellent catalytic performance. The catalyst is applied to the reaction of preparing hydrocarbon compounds by hydrogenating carbon dioxide, and the target hydrocarbon product has high selectivity.

[0005] In order to achieve the above object, the present invention provides a method for preparing a metal oxide, which comprises the following steps:

[0006] (1) mixing a metal oxide precursor, a surfactant and a precipitant in the presence of a liquid medium to obtain a mixed solution;

[0007] (2) subjecting the mixed solution of step (1) to hydrothermal treatment to obtain a solid product;

[0008] (3) calcining the solid product of step (2) to obtain a metal oxide;

[0009] Wherein, the surfactant is selected from at least one of hexadecyltrimethylammonium halide, polyvinylpyrrolidone and sodium dodecyl sulfate;

[0010] The precipitant is urea;

[0011] The metal oxide precursor is selected from at least one of compounds containing Group IIB, Group VIB, Group VIIB, Group IVB and Lanthanide metals.

[0012] The second aspect of the present invention provides a metal oxide obtained by the method described in the first aspect.

[0013] The third aspect of the present invention provides a catalyst, the catalyst comprising: the metal oxide and molecular sieve described in the second aspect;

[0014] Wherein, based on the total weight of the catalyst, the content of the molecular sieve is 35-90wt%; the content of the metal oxide is 10-65wt%.

[0015] The fourth aspect of the present invention provides a use of the catalyst described in the third aspect in the preparation of hydrocarbon compounds by hydrogenation of carbon dioxide.

[0016] A fifth aspect of the present invention provides a method for preparing hydrocarbon compounds by hydrogenating carbon dioxide, the method comprising: contacting and reacting carbon dioxide with hydrogen in the presence of a catalyst to obtain a target hydrocarbon product;

[0017] Wherein, the catalyst is the catalyst described in the third aspect.

[0018] The beneficial effects of the present invention include:

[0019] The metal oxide obtained by the method of the present invention makes the prepared catalyst have excellent catalytic performance. The catalyst is used in the reaction of preparing hydrocarbon compounds by hydrogenation of carbon dioxide, and the target hydrocarbon product has high selectivity. It can be seen from the experiment that the C 2 -C 4 The selectivity of olefins can reach up to 86.8%, C 5+ The selectivity of hydrocarbons can reach up to 65.2%. 4 The selectivity is low, the lowest is 5%, C 2 -C 4 The selectivity of alkanes is relatively low, reaching as low as 2.1%. DETAILED DESCRIPTION

[0020] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0021] One aspect of the present invention provides a method for preparing a metal oxide, the method comprising the following steps:

[0022] (1) mixing a metal oxide precursor and a precipitant in the presence of a liquid medium to obtain a mixed solution;

[0023] (2) subjecting the mixed solution of step (1) to hydrothermal treatment to obtain a solid product;

[0024] (3) calcining the solid product of step (2) to obtain a metal oxide;

[0025] Wherein, the surfactant is selected from at least one of hexadecyltrimethylammonium halide, polyvinylpyrrolidone and sodium dodecyl sulfate;

[0026] The precipitant is urea;

[0027] The metal oxide precursor is selected from at least one of compounds containing Group IIB, Group VIB, Group VIIB, Group IVB and Lanthanide metals.

[0028] In the preparation method provided by the present invention, a specific type of surfactant is mixed with a urea precipitant and a precursor of a metal oxide to obtain a mixed solution; then, after hydrothermal treatment, the obtained metal oxide makes the prepared catalyst have excellent catalytic performance. The catalyst of the present invention is applied to the preparation of hydrocarbon compounds by hydrogenation of carbon dioxide, and has the advantages of high catalytic activity and high selectivity of target hydrocarbon products. In addition, the preparation method of the metal oxide provided by the present invention has a simple process and shortens the time required for preparation.

[0029] According to the present invention, preferably, the mass ratio of the surfactant to the metal oxide precursor is 0.1-2:1, preferably 0.4-2:1, such as 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, 1.9:1, 2:1, and any value in the range formed by any two of these values. This preferred embodiment is conducive to improving the catalytic performance of the catalyst.

[0030] According to the present invention, preferably, the mass ratio of the precipitant to the metal oxide precursor is 1-8:1, preferably 1.5-8:1, such as 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, 7:1, 7.5:1, 8:1, and any value in the range formed by any two of these values. By adopting this preferred embodiment, the catalytic performance of the prepared catalyst is further improved.

[0031] According to the present invention, further preferably, the surfactant is hexadecyltrimethylammonium halide, polyvinylpyrrolidone and / or sodium dodecyl sulfate.

[0032] According to the present invention, preferably, the mass ratio of the hexadecyltrimethylammonium halide to polyvinylpyrrolidone and / or sodium dodecyl sulfate is 1:0.05-0.15.

[0033] According to the present invention, preferably, the hexadecyltrimethylammonium halide is hexadecyltrimethylammonium bromide and / or hexadecyltrimethylammonium chloride.

[0034] The inventors found during the research process that the catalytic performance of the prepared catalyst is more excellent by using a surfactant of a specific type and a specific ratio in combination with other substances.

[0035] The present invention has a wide range of choices for the type of the liquid medium, which can be any conventional liquid medium in the art. Preferably, the liquid medium is water and / or an organic solvent, preferably water.

[0036] The present invention has no particular limitation on the amount of the liquid medium, and the amount can be prepared by referring to conventional methods in the art. Preferably, the mass ratio of the surfactant to the liquid medium is 1:5-25.

[0037] Preferably, the precursor of the metal oxide is selected from at least one of lanthanum-containing compounds, cerium-containing compounds, zinc-containing compounds, cadmium-containing compounds, chromium-containing compounds, molybdenum-containing compounds, tungsten-containing compounds, manganese-containing compounds, titanium-containing compounds and zirconium-containing compounds.

[0038] According to the present invention, preferably, the precursor of the metal oxide is selected from at least one of a lanthanum-containing compound, a cerium-containing compound, a zinc-containing compound, a chromium-containing compound, a manganese-containing compound and a zirconium-containing compound.

[0039] In order to improve the catalytic performance of the catalyst, preferably, the precursor of the metal oxide is selected from at least two of lanthanum-containing compounds, cerium-containing compounds, zinc-containing compounds, chromium-containing compounds, manganese-containing compounds and zirconium-containing compounds.

[0040] More preferably, the precursor of the metal oxide is selected from at least one of a zinc-containing compound, a zirconium-containing compound, and optionally a lanthanum-containing compound, a cerium-containing compound, a chromium-containing compound and a manganese-containing compound.

[0041] In the present invention, the “optional at least one of lanthanum-containing compounds, cerium-containing compounds, chromium-containing compounds and manganese-containing compounds” means that at least one of lanthanum-containing compounds, cerium-containing compounds, chromium-containing compounds and manganese-containing compounds may be added, or at least one of lanthanum-containing compounds, cerium-containing compounds, chromium-containing compounds and manganese-containing compounds may not be added.

[0042] According to the present invention, preferably, the mass ratio of the zinc-containing compound, the zirconium-containing compound and at least one of the lanthanum-containing compound, the cerium-containing compound, the chromium-containing compound and the manganese-containing compound is 1:3-6:0-0.8, preferably 1:4-6:0.1-0.6.

[0043] According to the present invention, preferably, the zinc-containing compound is selected from at least one of zinc nitrate, zinc chloride and zinc sulfate; the zirconium-containing compound is selected from at least one of zirconium nitrate, zirconium chloride and zirconium sulfate; the lanthanum-containing compound is selected from at least one of lanthanum nitrate, lanthanum chloride and lanthanum sulfate; the cerium-containing compound is selected from at least one of cerium nitrate, cerium chloride and cerium sulfate; the chromium-containing compound is selected from at least one of chromium nitrate, chromium chloride and chromium sulfate; the manganese-containing compound is selected from at least one of manganese nitrate, manganese chloride and manganese sulfate. The above substances are all conventionally selected in the art and can be obtained commercially.

[0044] The present invention has no particular limitation on the order of adding the four substances, namely, the liquid medium, the surfactant, the metal oxide precursor and the precipitant, during the mixing process. The four substances may be added separately or together. In order to mix evenly, the embodiment of the present invention preferably adopts the method of first adding the metal oxide precursor, the liquid medium, the surfactant and then adding the precipitant.

[0045] Preferably, the mixing is performed under stirring conditions.

[0046] The present invention has no particular limitation on the stirring rate and time, which can be appropriately selected according to specific circumstances, as long as the purpose of uniform mixing is achieved.

[0047] Preferably, the conditions of the hydrothermal treatment in step (2) include: a temperature of 100-250° C., preferably 100-200° C.; and a time of 5-36 hours, preferably 6-24 hours. This preferred embodiment is more conducive to obtaining a catalyst with excellent catalytic performance.

[0048] The hydrothermal treatment of the present invention can be carried out in any reactor capable of carrying out hydrothermal treatment. Preferably, the hydrothermal treatment is carried out in a hydrothermal synthesis reactor.

[0049] The hydrothermal synthesis reactor (hydrothermal reactor) of the present invention is a conventional hydrothermal synthesis reactor in the art and is a closed container.

[0050] The present invention has no particular limitation on the hydrothermal treatment process. Specifically, the mixed solution obtained in step (1) can be subjected to hydrothermal treatment under hydrothermal treatment conditions, and then washed, separated, and dried to obtain the solid product.

[0051] The present invention has no particular limitation on the separation method, and the separation can be carried out by referring to conventional technical means in the art, as long as a solid product can be obtained.

[0052] The present invention has no particular limitation on the specific conditions of the washing and drying, and the washing and drying can be carried out according to conventional methods in the art.

[0053] The calcination conditions of the present invention are conventionally selected in the art. Preferably, the calcination conditions of step (3) include: a temperature of 300-600°C, preferably 350-550°C; a time of 2-10 hours, preferably 2-6 hours. The calcination is generally carried out in an air atmosphere, which may include a flowing atmosphere or a static atmosphere.

[0054] According to a particularly preferred embodiment of the present invention, a method for preparing a metal oxide comprises the following steps:

[0055] (1) mixing a metal oxide precursor and a precipitant in the presence of a liquid medium to obtain a mixed solution;

[0056] (2) subjecting the mixed solution of step (1) to hydrothermal treatment to obtain a solid product;

[0057] (3) calcining the solid product of step (2) to obtain a metal oxide;

[0058] Wherein, the surfactant includes hexadecyltrimethylammonium halide, polyvinylpyrrolidone and / or sodium lauryl sulfate;

[0059] The mass ratio of the hexadecyltrimethylammonium halide to polyvinylpyrrolidone and / or sodium lauryl sulfate is 1:0.05-0.15;

[0060] The precipitant is urea;

[0061] The metal oxide precursor is selected from at least one of compounds containing Group IIB, Group VIB, Group VIIB, Group IVB and Lanthanide metals;

[0062] The mass ratio of the surfactant to the metal oxide precursor is 0.4-2:1;

[0063] The mass ratio of the precipitant to the metal oxide precursor is 1.5-8:1.

[0064] The above preferred embodiment is further conducive to obtaining a catalyst with excellent catalytic performance. The catalyst of the present invention is used in the preparation of hydrocarbon compounds by hydrogenation of carbon dioxide, and has the advantages of high catalytic activity and high selectivity of target hydrocarbon products.

[0065] The second aspect of the present invention provides a metal oxide obtained by the method described in the first aspect.

[0066] The third aspect of the present invention provides a catalyst, the catalyst comprising: the metal oxide and molecular sieve described in the second aspect;

[0067] Wherein, based on the total weight of the catalyst, the content of the molecular sieve is 35-90wt%; the content of the metal oxide is 10-65wt%.

[0068] According to the present invention, preferably, based on the total weight of the catalyst, the content of the molecular sieve is 45-70 wt%; and the content of the metal oxide is 30-55 wt%.

[0069] The present invention has no particular limitation on the type of the molecular sieve, which can be a conventional choice in the art. Preferably, the molecular sieve is at least one of CHA structure, MFI structure, MFS structure and MMW structure molecular sieve, preferably at least one of SAPO-34, ZSM-5 and ZSM-57 molecular sieves. Using this preferred embodiment, the prepared catalyst is applied to the reaction of preparing hydrocarbon compounds by hydrogenation of carbon dioxide, which is conducive to improving the selectivity of the target hydrocarbon product.

[0070] According to the present invention, preferably, the silicon to aluminum atomic ratio of the molecular sieve is 0.05-400, preferably 0.1-300.

[0071] Preferably, the silicon to aluminum atomic ratio of the SAPO-34 molecular sieve is 0.1-0.5.

[0072] Preferably, the silicon to aluminum atomic ratio of the ZSM-5 molecular sieve is 10-150.

[0073] Preferably, the silicon to aluminum atomic ratio of the ZSM-57 molecular sieve is 15-30.

[0074] Preferably, the molecular sieve is a hydrogen-type molecular sieve.

[0075] The present invention has no particular limitation on the method for obtaining the hydrogen molecular sieve, and the method can be carried out according to conventional methods in the art. The present invention preferably uses an ammonia exchange method to obtain the hydrogen molecular sieve.

[0076] The ammonia exchange method of the present invention can be carried out by referring to the conventional ammonia exchange method in the art, and the present invention will not be described in detail here.

[0077] The present invention has no particular limitation on the preparation method of the catalyst, and the preparation method can be carried out according to conventional methods in the art. The present invention preferably adopts a physical mixing method.

[0078] According to a specific embodiment of the present invention, the metal oxide and the molecular sieve are ground to obtain a catalyst.

[0079] The particle size of the catalyst is a conventional choice in the art. Preferably, the particle size of the catalyst is 10-80 mesh.

[0080] The present invention has no particular limitation on the method for obtaining the catalyst with the particle size, and the method may refer to conventional technical means in the art.

[0081] The fourth aspect of the present invention provides a use of the catalyst described in the third aspect in the preparation of hydrocarbon compounds by hydrogenation of carbon dioxide.

[0082] A fifth aspect of the present invention provides a method for preparing hydrocarbon compounds by hydrogenating carbon dioxide, the method comprising: contacting and reacting carbon dioxide with hydrogen in the presence of a catalyst to obtain a target hydrocarbon product;

[0083] Wherein, the catalyst is the catalyst described in the third aspect.

[0084] According to the present invention, preferably, the molar ratio of hydrogen to carbon dioxide is 3-15:1, preferably 3-10:1.

[0085] According to the present invention, preferably, the reaction conditions are: temperature of 250-450°C, preferably 320-450°C; pressure of 0.3-20MPa, preferably 2-15MPa; mass space velocity of carbon dioxide of 0.01-10h -1 , preferably 0.05-8h -1 .

[0086] According to the present invention, preferably, the target hydrocarbon product is C 2 -C 4 Olefins and / or C 5+ Hydrocarbons.

[0087] The reaction of the present invention can be carried out in various reactors commonly used in the art. Preferably, the reaction is carried out in a fixed bed reactor.

[0088] Preferably, the catalyst is activated before use.

[0089] The present invention has no particular limitation on the activation method, and the activation may be performed according to conventional methods in the art.

[0090] According to a specific embodiment of the present invention, the catalyst is activated at 380-450° C. for 2-8 hours under the action of reducing gas or inert gas.

[0091] The present invention has a wide range of selection for the type of the reducing gas. Preferably, the reducing gas is hydrogen.

[0092] The present invention has a wide range of selection for the type of the inert gas. Preferably, the inert gas is nitrogen.

[0093] The present invention will be described in detail below through examples.

[0094] In the following examples, the conversion rate of carbon dioxide was calculated using the internal standard method, and the selectivity of the product was calculated using the normalization method, and the formula is as follows:

[0095] Carbon dioxide conversion rate = [(carbon dioxide moles in the feed gas) - (carbon dioxide moles in the product)] / (carbon dioxide moles in the feed gas) × 100%;

[0096] Selectivity of hydrocarbon products = molar number of carbon in hydrocarbon products / total molar number of organic carbon in hydrocarbon products × 100%;

[0097] CO selectivity = molar number of CO carbon in the product / [molar number of carbon dioxide carbon in the feed gas - molar number of carbon dioxide carbon in the product] × 100%;

[0098] The specific sources of the molecular sieve catalysts used in the following examples are shown in Table 1.

[0099] Table 1

[0100]

[0101] Example 1

[0102] Preparation of metal oxides

[0103] Add 7.397g zirconium nitrate pentahydrate, 1.420g zinc nitrate hexahydrate, 4g hexadecyltrimethylammonium bromide, 0.5g polyvinylpyrrolidone, then add 80mL water to dissolve, stir evenly, add 17.9g urea, stir for 2h, and obtain a mixed solution. Transfer the mixed solution to a 200mL hydrothermal kettle and react at 120℃ for 20h. Cool the obtained reaction product, wash it, centrifuge it, dry it at 110℃ overnight, and roast it at 500℃ for 4h to obtain a ZnZrOx sample.

[0104] Catalyst preparation

[0105] 0.5 g of hydrothermally synthesized ZnZrOx and 1.0 g of HSAPO-34 were fully ground and mixed to obtain a catalyst, which was recorded as C-1. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0106] Example 2

[0107] Add 7.377g zirconium nitrate pentahydrate, 1.418g zinc nitrate hexahydrate, 0.597g lanthanum nitrate, 4g hexadecyltrimethylammonium chloride, then add 80mL water to dissolve, stir evenly, add 50.3g urea, stir for 2h, and obtain a mixed solution. Transfer the mixed solution to a 200mL hydrothermal kettle and react at 140℃ for 15h. Cool the obtained reaction product, wash it, centrifuge it, dry it at 110℃ overnight, and roast it at 500℃ for 4h to obtain a ZnZrLaOx sample.

[0108] Catalyst preparation

[0109] 0.5 g of hydrothermally synthesized ZnZrLaOx and 1.0 g of HSAPO-34 were fully ground and mixed to obtain a catalyst, which was recorded as C-2. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0110] Example 3

[0111] Add 7.381g zirconium nitrate pentahydrate, 1.419g zinc nitrate hexahydrate, 0.659g 50wt% manganese nitrate aqueous solution, then add 20mL water to dissolve, stir evenly, add 4.0g hexadecyltrimethylammonium bromide and 0.5g sodium dodecyl sulfate, add 80mL water to dissolve, continue to stir evenly, add 18.8g urea, stir for 2h, and obtain a mixed solution. Transfer the mixed solution to a 200mL hydrothermal kettle and react at 120℃ for 20h. Cool the obtained reaction product, wash it, centrifuge it, dry it at 60℃ overnight, and roast it at 500℃ for 4h to obtain a ZnZrMnOx sample.

[0112] Catalyst preparation

[0113] 0.5 g of hydrothermally synthesized ZnZrMnOx and 1.0 g of HSAPO-34 were fully ground and mixed to obtain a catalyst, which was recorded as C-3. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0114] Example 4

[0115] Preparation of metal oxides

[0116] Add 7.397g zirconium nitrate pentahydrate, 1.420g zinc nitrate hexahydrate, 4.0g hexadecyltrimethylammonium bromide and 0.5g polyvinylpyrrolidone, then add 80mL water to dissolve, stir evenly, add 17.9g urea, stir for 2h to obtain a mixed solution. Transfer the mixed solution to a 200mL hydrothermal kettle and react at 160℃ for 10h. Cool the obtained reaction product, wash it, centrifuge it, dry it at 110℃ overnight, and roast it at 500℃ for 4h to obtain a ZnZrOx sample.

[0117] Catalyst preparation

[0118] 0.5 g of hydrothermally synthesized ZnZrOx and 1.0 g of HZSM-5 were fully ground and mixed to obtain a catalyst, which was recorded as C-4. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0119] Example 5

[0120] Preparation of metal oxides

[0121] Add 7.397g zirconium nitrate pentahydrate, 1.420g zinc nitrate hexahydrate, 15.0g polyvinyl pyrrolidone (PVP), then add 80mL water to dissolve, stir evenly, add 17.9g urea, stir for 2h, and obtain a mixed solution. Transfer the mixed solution to a 200mL hydrothermal kettle and react at 120℃ for 20h. Cool the obtained reaction product, wash it, centrifuge it, dry it at 110℃ overnight, and roast it at 500℃ for 4h to obtain a ZnZrOx sample.

[0122] Catalyst preparation

[0123] 0.6 g of hydrothermally synthesized ZnZrOx and 0.8 g of HZSM-5 were fully ground and mixed to obtain a catalyst, which was recorded as C-5. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0124] Example 6

[0125] Preparation of metal oxides

[0126] Add 7.397g zirconium nitrate pentahydrate, 1.420g zinc nitrate hexahydrate, 4.0g hexadecyltrimethylammonium bromide and 0.5g polyvinylpyrrolidone, then add 80mL water to dissolve, stir evenly, add 17.9g urea, stir for 2h to obtain a mixed solution. Transfer the mixed solution to a 200mL hydrothermal kettle and react at 120℃ for 20h. Cool the obtained reaction product, wash it, centrifuge it, dry it at 110℃ overnight, and roast it at 500℃ for 4h to obtain a ZnZrOx sample.

[0127] Catalyst preparation

[0128] Preparation of H-ZSM-57: In a hydrothermal synthesis reactor, add Na-ZSM-57 molecular sieve powder to the pre-prepared 1 mol / L NH 4 In a Cl aqueous solution, the solid-liquid mass ratio is 1:10, and the exchange reaction is carried out at 80°C for 2h under stirring, and then vacuum filtered and washed with water. After the above exchange, filtration and washing operations are carried out 3 times, it is dried at 120°C for 6h. Then, H-ZSM-57 is obtained after calcination at 550°C for 4h.

[0129] 0.5 g of hydrothermally synthesized ZnZrOx and 0.5 g of H-ZSM-57 were fully ground and mixed to obtain a catalyst, which was recorded as C-6. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0130] Example 7

[0131] The method of Example 1 was followed, except that during the preparation of the metal oxide, the reaction was carried out at 95° C. for 20 h to obtain a catalyst, which was recorded as C-7. The catalyst was pressed into tablets and granulated into 40-60 mesh particles for subsequent reactions.

[0132] Comparative Example 1

[0133] The method of Example 1 was followed, except that urea was replaced with an equal mass of sodium hydroxide to obtain a catalyst, which was recorded as D-1. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0134] Comparative Example 2

[0135] The method of Example 1 was followed, except that, during the preparation of the metal oxide, hexadecyltrimethylammonium bromide and polyvinylpyrrolidone were not added, but 4.5 g of ethanol was added to obtain a catalyst, which was recorded as D-2. The catalyst was tableted and granulated into 40-60 mesh particles for subsequent reactions.

[0136] Comparative Example 3

[0137] Preparation of metal oxides

[0138] Place a three-necked flask in a constant temperature water bath at 95°C, add 7.397g zirconium nitrate pentahydrate, 1.420g zinc nitrate hexahydrate, 4g hexadecyltrimethylammonium bromide, 0.5g polyvinylpyrrolidone, then add 80mL water to dissolve, stir evenly, add 17.9g urea, stir evenly, age for 20h, cool and wash, centrifuge, dry at 110°C overnight, and calcine at 500°C for 4h to obtain a ZnZrOx sample.

[0139] Catalyst preparation

[0140] The method of Example 1 was followed to obtain a catalyst, which was designated as D-3. The catalyst was tableted and granulated to prepare 40-60 mesh particles for subsequent reactions.

[0141] Test Example 1

[0142] 0.5 g of the catalyst prepared in the examples and comparative examples was loaded into a fixed bed reactor with a quartz tube lining (quartz tube inner diameter 8 mm) and an inner diameter of 13 mm. The temperature was raised to 400° C. at 5° C. / min under a hydrogen atmosphere, maintained for 2 hours, and then cooled to 360° C. The reaction raw gas was introduced, the reaction pressure was 3.0 MPa, the molar ratio of hydrogen to carbon dioxide was 3:1, and the mass space velocity of carbon dioxide was 1.63 h -1 The reaction temperature was 360°C and the reaction time was 18 hours. The reaction results are shown in Table 2.

[0143] Table 2

[0144]

[0145]

[0146] The results in Table 2 show that the catalyst prepared by the metal oxide obtained by the method of the present invention is applied to the preparation of hydrocarbon compounds by hydrogenation of carbon dioxide, and the target hydrocarbon product has high selectivity, and the C 2 -C 4 The selectivity of olefins can reach up to 86.8%, C 5+ The selectivity of hydrocarbons can reach up to 65.2%. 4 The selectivity is low, the lowest is 5%, C 2 -C 4 The selectivity of alkanes is relatively low, and the lowest can reach 2.1%. This shows that the catalyst provided by the present invention has excellent catalytic performance.

[0147] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A method for preparing a metal oxide, the method comprising the following steps: (1) mixing a metal oxide precursor, a surfactant and a precipitant in the presence of a liquid medium to obtain a mixed solution; (2) subjecting the mixed solution of step (1) to hydrothermal treatment to obtain a solid product; (3) calcining the solid product of step (2) to obtain a metal oxide; Wherein, the surfactant is selected from at least one of hexadecyltrimethylammonium halide, polyvinylpyrrolidone and sodium dodecyl sulfate; The precipitant is urea; The metal oxide precursor is selected from at least one of compounds containing Group IIB, Group VIB, Group VIIB, Group IVB and Lanthanide metals.

2. The method according to claim 1, wherein: The mass ratio of the surfactant to the metal oxide precursor is 0.1-2:1, preferably 0.4-2:1; Preferably, the mass ratio of the precipitant to the metal oxide precursor is 1-8:1, preferably 1.5-8:1; Preferably, the surfactant comprises hexadecyltrimethylammonium halide, and polyvinylpyrrolidone and / or sodium lauryl sulfate; Preferably, the mass ratio of the hexadecyltrimethylammonium halide to polyvinylpyrrolidone and / or sodium dodecyl sulfate is 1:0.05-0.15; Preferably, the hexadecyltrimethylammonium halide is hexadecyltrimethylammonium bromide and / or hexadecyltrimethylammonium chloride.

3. The method according to claim 1 or 2, wherein: The metal oxide precursor is selected from at least one of a lanthanum-containing compound, a cerium-containing compound, a zinc-containing compound, a chromium-containing compound, a manganese-containing compound and a zirconium-containing compound; Preferably, the precursor of the metal oxide is selected from at least one of a zinc-containing compound and a zirconium-containing compound, and optionally a lanthanum-containing compound, a cerium-containing compound, a chromium-containing compound and a manganese-containing compound; Preferably, the mass ratio of the zinc-containing compound, the zirconium-containing compound, and at least one of the lanthanum-containing compound, the cerium-containing compound, the chromium-containing compound, and the manganese-containing compound is 1:3-6:0-0.8, preferably 1:4-6:0.1-0.6; Preferably, the zinc-containing compound is selected from at least one of zinc nitrate, zinc chloride and zinc sulfate; the zirconium-containing compound is selected from at least one of zirconium nitrate, zirconium chloride and zirconium sulfate; the lanthanum-containing compound is selected from at least one of lanthanum nitrate, lanthanum chloride and lanthanum sulfate; the cerium-containing compound is selected from at least one of cerium nitrate, cerium chloride and cerium sulfate; the chromium-containing compound is selected from at least one of chromium nitrate, chromium chloride and chromium sulfate; the manganese-containing compound is selected from at least one of manganese nitrate, manganese chloride and manganese sulfate.

4. The method according to any one of claims 1 to 3, wherein: The conditions of the hydrothermal treatment in step (2) include: a temperature of 100-250° C., preferably 100-200° C.; a time of 5-36 h, preferably 6-24 h; Preferably, the calcination conditions in step (3) include: a temperature of 300-600° C., preferably 350-550° C.; and a calcination time of 2-10 h, preferably 2-6 h.

5. The metal oxide obtained by the method according to any one of claims 1 to 4.

6. A catalyst, comprising: The metal oxide and molecular sieve according to claim 5; Wherein, based on the total weight of the catalyst, the content of the molecular sieve is 35-90wt%; the content of the metal oxide is 10-65wt%.

7. The catalyst according to claim 6, wherein Based on the total weight of the catalyst, the content of the molecular sieve is 45-70wt%; the content of the metal oxide is 30-55wt%; Preferably, the molecular sieve is selected from at least one of CHA structure, MFI structure, MFS structure and MMW structure molecular sieves, preferably selected from at least one of SAPO-34, ZSM-5 and ZSM-57 molecular sieves; Preferably, the silicon to aluminum atomic ratio of the molecular sieve is 0.05-400, preferably 0.1-300.

8. Use of the catalyst according to claim 6 or 7 in the preparation of hydrocarbon compounds by hydrogenation of carbon dioxide.

9. A method for preparing hydrocarbon compounds by hydrogenating carbon dioxide, the method comprising: Under the action of a catalyst, carbon dioxide and hydrogen are contacted and reacted to obtain target hydrocarbon products; Wherein, the catalyst is the catalyst according to claim 6 or 7.

10. The method according to claim 9, wherein: The molar ratio of hydrogen to carbon dioxide is 3-15:1, preferably 3-10:1; Preferably, the reaction conditions are: temperature of 250-450°C, preferably 320-450°C; pressure of 0.3-20MPa, preferably 2-15MPa; mass space velocity of carbon dioxide of 0.01-10h -1 , preferably 0.05-8h -1 ; Preferably, the target hydrocarbon product is C2-C4 olefins and / or C 5+ Hydrocarbons.

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