CN111644169B - Metal composite modified nano zirconia catalyst and its preparation method and application - Google Patents

Abstract

The invention discloses a metal composite modified nano-zirconia catalyst and a preparation method and application thereof, belonging to the technical field of synthesis gas chemical industry and catalyst preparation. The preparation method of the catalyst comprises the following steps: putting a mixed solution consisting of a soluble zirconium salt solution, an alkali solution, a surfactant and hydrogen peroxide into a hydrothermal reaction at the temperature of between 150 and 200 ℃ for 10 to 30 hours to obtain a zirconium salt precursor; then calcining and grinding to obtain ZrO ₂ A nanopowder; then ZrO is reacted ₂ Nanopowder and metal oxide M _x O _y Mixing with dispersant, and grinding. The metal composite modified nano zirconia catalyst prepared by the invention can increase oxygen vacancy and improve the conversion rate of CO, and the prepared low-carbon olefin has high selectivity and good stability. In addition, the catalyst has simple preparation process and lower raw material cost, and is suitable for industrial large-scale production.

Description

Metal composite modified nano zirconia catalyst and its preparation method and application

technical field

The invention belongs to the technical field of synthesis gas chemical industry and catalyst preparation, and in particular relates to a metal composite modified nano-zirconia catalyst and its preparation method and application.

Background technique

Low-carbon olefins refer to ethylene, propylene and butene, which are key intermediates for synthetic plastics, fibers and various chemical materials. They are a very important basic organic chemical raw material and the cornerstone of the modern chemical industry. In recent years, with the rapid growth of the national economy, the demand for petroleum and petrochemical products has increased rapidly. Insufficient petroleum resources have gradually highlighted the contradiction between supply and demand of low-carbon olefins, seriously restricting the healthy and stable development of my country's petrochemical industry and petrochemical products.

"Rich in coal, poor in oil, and low in gas" is the characteristic of my country's energy resources. my country's abundant coal reserves can not only meet the needs of 74% of the country's electricity, 800 million tons of crude steel, 2.4 billion tons of cement, and 70 million tons of synthetic ammonia. Coal is used to produce oil, olefins, methanol, ethylene glycol and other chemical raw materials. Synthesis gas is mainly composed of carbon monoxide (CO) and hydrogen (H ₂ ). It is a raw material gas for chemical synthesis and can be converted from carbon-containing resources such as coal, oil, natural gas, coke oven gas and biomass. However, with the continuous rise of oil prices, scientists proposed the concept of C1 chemistry. Since then, the research on the utilization of syngas has attracted great attention from researchers from all over the world. Therefore, the development of new coal chemical technology and the production technology of low-carbon olefins with syngas as the main hub are feasible routes for the production of low-carbon olefins from non-petroleum resources.

The most concerned about the production of low-carbon olefins from syngas are the following two routes: (1) direct conversion of syngas to low-carbon olefins through Fischer-Tropsch synthesis (FTS); (2) the use of oxide-molecular sieve dual-functional catalysts ( XO-ZEO) to prepare light olefins. For example, in Fischer-Tropsch synthesis, although the conversion rate of CO is very high, the distribution of products _is limited by the distribution of ASF, and the selectivity of light olefins can only reach 60%. The carbon utilization rate of the catalyst is very low, and the active components of the catalyst are easily lost. The following aspects need to be paid attention to in the production of low-carbon olefins by the dual-functional catalytic route: optimize and adjust the pore structure of the molecular sieve, improve its thermal stability and inhibit the occurrence of carbon deposition; the "thermal coupling effect" and "thermal coupling effect" of the two active components Product conversion coupling effect", so that the two active components can be properly matched to effectively control the product distribution; build a micro-zone environment with good mass and heat transfer performance, so that intermediates and products can be transferred quickly and effectively, and prevent the formation of low-carbon olefins secondary hydrogenation reaction.

_ZrO2 itself has a variety of chemical and physical properties, and its surface is acidic, basic, oxidizing, and reducing at the same time. It is also a p-type semiconductor, and it is easy to generate oxygen holes. ZrO ₂ is widely used in catalytic systems as a catalyst active component, catalyst support or assistant. The concept of isomerization synthesis was first proposed by Pichler, and it was found that zirconia can directly convert synthesis gas into isobutene and isobutane (Pichler H, Ziesecke KH. Isosynthesis by reduced oxidecatalysts[J]. Brennst Chem,1949,30:13 -80.). Xu Longya (application number: CN 92109866.9) discloses a method for preparing an iron-manganese catalyst for CO hydrogenation to produce low-carbon olefins. When MgO is loaded, the conversion rate of CO is 83.4%, and the selectivity of low-carbon olefins is 62.1%. Although The conversion of CO is high, but the selectivity of light olefins is low.

Contents of the invention

In view of the problems or defects in the above-mentioned prior art, the object of the present invention is to provide a metal composite modified nano-zirconia catalyst and its preparation method and application.

In order to realize one of the above-mentioned purposes of the present invention, the technical scheme adopted in the present invention is as follows:

A method for preparing a metal composite modified nano-zirconia catalyst, the method specifically includes the following steps:

(1) Mix soluble zirconium salt solution, alkali solution, and surfactant according to the proportioning ratio, and stir evenly to obtain a mixed solution 1; then add hydrogen peroxide to the mixed solution 1, and continue to stir evenly to obtain a mixed solution 2; The mixed solution 2 is transferred to a hydrothermal reaction kettle, sealed, and the reaction kettle is heated to 150-200° C. for constant temperature hydrothermal reaction for 10-30 hours. After the reaction is completed, it is cooled to room temperature, and the obtained product is centrifuged, washed, and dried. Obtain ZrO ₂ precursor;

(2) Place the ZrO ₂ precursor described in step (1) in a muffle furnace, and heat it up to 300-700°C for 3-8 hours in an air atmosphere, and then calcinate at a constant temperature for 3-8 hours. After the calcination, white ZrO ₂ powder is obtained;

(3) the white _ZrO powder described in step (2) is mixed with an appropriate amount of grinding aid, and ground for 10 to 40 min to obtain ZrO _nano powder;

(4) Mixing the ZrO ₂ nano powder and the metal oxide M _x O _y in the step (3) according to the proportioning ratio, and grinding the obtained mixture for 10-40 min to obtain the metal composite modified nano-zirconia catalyst.

Further, in the above technical scheme, in the soluble zirconium salt solution described in step (1), the solute is a soluble zirconium salt, and the solvent is any one of deionized water, ethanol, acetone, etc.; wherein: the soluble zirconium salt is Any one of zirconium nitrate pentahydrate (Zr(NO ₃ ) ₄ ·5H ₂ O), zirconyl nitrate, zirconium chloride, zirconium acetate, zirconium citrate, zirconium n-propoxide, and the like.

Preferably, in the above technical solution, the soluble zirconium salt described in step (1) is zirconium nitrate pentahydrate.

Further, in the above technical solution, in the soluble zirconium salt solution described in step (1), the dosage ratio of the soluble zirconium salt to the solvent is (15-30) g: (50-120) mL.

Preferably, in the above technical solution, in the soluble zirconium salt solution described in step (1), the dosage ratio of the soluble zirconium salt to the solvent is (15-30) g: (70-90) mL.

Further, in the above technical solution, the alkaline solution in step (1) may be any one or more of urea solution, ammonia solution or hydrazine hydrate solution. The alkali solution that the present invention adopts, its effect is precipitating agent.

Preferably, in the above technical solution, the concentration of the alkali solution in step (1) is 1-10 mol/L, more preferably 5-8 mol/L.

Further, in the above technical solution, the surfactant described in step (1) is preferably polyethylene glycol 600. The surfactant molecule used in the present invention contains hydrophilic groups and hydrophobic groups, and is often used to reduce the surface energy of ultrafine particles and prevent newborn particles from agglomerating. Therefore, the use of surfactants is often beneficial to obtain ultrafine powders.

Further, in the above technical solution, the mass ratio of the soluble zirconium salt in the soluble zirconium salt solution in the step (1), the alkali in the alkali solution, and the surfactant is (15-30): (20-60): (1~10).

Further, in the above technical solution, the dosage ratio of the surfactant and hydrogen peroxide in step (1) is (1-10) parts by mass: (3-10) parts by volume, wherein: between the parts by mass and parts by volume is Based on g:mL.

Further, in the above technical solution, the time for the two stirrings in step (1) is not limited, as long as the uniform mixing of the raw materials can be achieved, for example, the two stirring times can be 10-50 minutes.

Further, in the above technical solution, the hydrothermal reaction kettle in step (1) has a polytetrafluoroethylene lining, and the volume of the hydrothermal reaction kettle is 100-500mL.

Further, in the above technical solution, the filling degree of the mixed liquid 2 in step (1) is preferably controlled at 50% to 80% of the volume of the reactor.

Further, in the above technical solution, the temperature of the hydrothermal reaction in step (1) is preferably 170-190° C., and the reaction time is preferably 15-25 hours.

Further, in the above technical solution, the solvent used for the washing described in step (1) is deionized water.

Further, in the above technical solution, the number of times of centrifugation and washing in step (1) is not limited, it can be 1 time, 2 times or more, more preferably 1-3 times.

Further, in the above technical solution, the drying process described in step (1) specifically includes placing the solid product obtained by centrifugation and washing in an oven, controlling the drying temperature of the oven to be 40-150° C., and the drying time to be 8-24 hours.

Preferably, in the above technical solution, the drying temperature in step (1) is 50-70° C., and the drying time is 10-14 hours.

Furthermore, in the above technical solution, the hydrogen peroxide used in step (1) has the function of inhibiting the reduction of zirconium ions (Zr ⁴⁺ ) in the zirconium salt.

Furthermore, in the above technical solution, the calcination temperature in step (2) is preferably 450-600° C., and the calcination time is preferably 4-6 hours. The purpose of the calcination in the present invention is to convert the precursor hydroxide of zirconium into zirconium oxide.

Further, in the above technical scheme, the grinding aid described in step (3) is an alcohol organic solvent with a branched chain structure, for example, the alcohol organic solvent can be isopropanol or 2-butanol, more preferably isopropanol alcohol. The invention adopts the alcohol organic solvent with a branched chain structure, which has many reactive points, can obviously inhibit powder agglomeration during the grinding process, and is beneficial to obtain products with smaller particle diameters.

Further, in the above technical solution, the particle size of the _ZrO2 nano powder described in step (3) is 30-80nm.

Further, in the above technical solution, the mass ratio of the grinding aid to the white ZrO ₂ powder in step (3) is 20-40:100.

Further, in the above technical scheme, in the metal oxide M _x O _y described in step (4), the M element is any one of Zn, Ce, Y, and In, the x is 1 or 2, and the y is 1 or 2 or 3. For example, the metal oxide M _x O _y may be any one of ZnO, CeO ₂ , Y ₂ O ₃ , and I ₂ O ₃ .

Further, in the above technical solution, the mass ratio of the metal oxide M _x O _y to the ZrO ₂ nanopowder in step (4) is 0.5-2:100.

Further, in the above technical scheme, a dispersant is also included in the mixture described in step (4), and the dispersant is preferably a polycarboxylic acid, and the polycarboxylic acid is selected from oxalic acid, malonic acid, malonic acid, butanedioic acid Any one or more of acid, adipic acid, etc.

Preferably, in the above technical scheme, the dispersant described in step (4) is glyceric acid.

Further, in the above-mentioned technical scheme, the addition amount of the dispersant described in the step (4) is no more than 5% of the quality of the _ZrO2nano powder.

Further, the above-mentioned technical scheme, the purpose of grinding described in step (4) is to utilize metal modification ZrO ₂ nanopowder.

The second object of the present invention is to provide a metal composite modified nano-zirconia catalyst prepared by the method described above.

The third object of the present invention is to provide the application of the metal composite modified nano-zirconia catalyst prepared by the above-mentioned method in catalytic CO hydrogenation.

The metal composite modified nano-zirconia catalyst of the present invention can simultaneously improve the CO hydrogenation conversion rate and the mechanism of low-carbon olefin selectivity as follows:

Oxygen vacancies on the surface of _ZrO2 can activate CO to form formic acid species, which can be hydrogenated to methoxyl species under _H2 atmosphere. However, the _H2 dissociation ability of _ZrO2 is weak and its CO conversion rate is low. However, the metal composite modified nano-zirconia catalyst of the present invention can promote the dissociation and adsorption of _H2 , form hydrogen species that can participate in the hydrogenation reaction, improve the conversion rate of CO, and selectivity of low-carbon olefins.

Compared with the prior art, the present invention has the following beneficial effects:

(1) The metal composite modified nano-zirconia catalyst prepared by the present invention can increase oxygen vacancies, improve CO hydrogenation conversion rate, have high selectivity for low-carbon olefins, and have good stability.

(2) The preparation process of the catalyst is simple, the raw material cost is relatively low, and it is suitable for large-scale industrial production.

(3) In the process of preparing the metal composite modified nano-zirconia catalyst, the particle size of the prepared zirconium oxide catalyst is reduced by adding the surfactant polyethylene glycol 600, and the ultra-fine powder of zirconium oxide is obtained.

(4) In the present invention, grinding aid is added after calcination, which inhibits the agglomeration of zirconia ultrafine powder, improves the dispersibility of the prepared catalyst, and reduces the selectivity of methane in the process of CO hydrogenation.

(5) In the grinding process of _the metal oxides _MxOy and _ZrO2 , the present invention adds a dispersant, which not only effectively suppresses the generation of _CO2 , but also improves the selectivity of low-carbon olefins and the ratio of olefins.

(6) During the CO hydrogenation reaction process of the present invention, the synergistic effect of the surfactant, the grinding aid and the dispersant improves the product distribution of the catalyst, effectively inhibits the carbon deposition of the catalyst, and improves the stability of the catalyst.

Detailed ways

The present invention will be described in further detail below through examples of implementation. This implementation case is carried out on the premise of the technology of the present invention, and the detailed implementation and specific operation process are given to illustrate the inventiveness of the present invention, but the protection scope of the present invention is not limited to the following implementation cases.

From the information contained herein, various changes in the precise description of the invention will readily become apparent to those skilled in the art without departing from the spirit and scope of the appended claims. It should be understood that the scope of the present invention is not limited to the processes, properties or components defined, since these embodiments, as well as other descriptions, are only intended to illustrate certain aspects of the invention. In fact, various changes to the embodiments of the present invention that can be obviously made by those skilled in the art or related fields fall within the scope of the appended claims.

In order to better understand the present invention but not to limit the scope of the present invention, all figures representing dosage, percentage, and other numerical values used in this application should be understood as being modified by the word "about" in all cases. Accordingly, unless expressly indicated otherwise, the numerical parameters set forth in the specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained. At a minimum, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques.

In the following examples, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art.

Example 1

A method for preparing a metal composite modified nano-zirconia catalyst of the present embodiment, the method comprises the following steps:

(1) Preparation of ZrO ₂ precursor

(a) Preparation of soluble zirconium salt solution: Weigh 17.1g of zirconium nitrate pentahydrate (Zr(NO ₃ ) ₄ 5H ₂ O), dissolve the weighed zirconium nitrate pentahydrate in 80mL deionized water, and Under the condition of /min, stir mechanically for 3min to obtain a soluble zirconium salt solution;

(b) Preparation of urea solution: Weigh 38.3g of urea ((NH ₂ ) ₂ CO) particles, dissolve the weighed urea in 80mL of deionized water, and stir mechanically for 5min at a speed of 300rad/min to obtain urea solution;

(c) Mix the soluble zirconium salt solution obtained in step (a), the urea solution obtained in step (b), and 1 g of polyethylene glycol 600, and mechanically stir for 10 min at a rotating speed of 500 rad/min to obtain a homogeneous mixed solution 1; Add 5mL of hydrogen peroxide to the mixed solution 1, and continue to mechanically stir for 30min under the condition of a rotating speed of 500rad/min to completely dissolve it to obtain a uniform mixed solution 2; In a stainless steel reaction kettle lined with ethylene, seal it, raise the temperature of the reaction kettle to 180°C for a constant temperature hydrothermal reaction for 20 hours, after the reaction, cool to room temperature, alternately centrifuge and wash the obtained product once, and place the obtained solid product in a Dry in an oven, the drying temperature is 60°C, and the drying time is 12h to obtain the ZrO ₂ precursor;

(2) Place the _ZrO2 precursor described in step (1) in a muffle furnace, and heat it up to 500°C for 4 hours at a constant temperature for calcination in an air atmosphere. After the calcination, white _ZrO2 powder is obtained;

(3) the white ZrO powder described in step (2) is mixed with grinding aid isopropanol, and ground for 20 min to obtain ZrO _nano powder, the particle diameter of _the ZrO _nano powder is 30-80nm; wherein: the The mass ratio of grinding aid to white _ZrO2 powder is 30:100.

(4) ZrO described in step (3) _Nanopowder , ZnO and dispersant are mixed, and the gained mixture is ground for 20min to obtain the described metal composite modified nano-zirconia catalyst, which is marked as 0.5% Zn-ZrO ₂ ; wherein : the dispersant is glyceric acid; the addition of the dispersant is 3% of the quality of the _ZrO2 nanometer powder; the mass ratio of the ZnO to the _ZrO2 nanometer powder is 0.5:100.

Example 2

A kind of preparation method of metal composite modified nano-zirconia catalyst of the present embodiment, described method is basically the same as embodiment 1, difference only is: the ZnO described in the step (4) of the present embodiment and ZrO ₂ nanopowder The mass ratio is 1:100. Therefore, correspondingly, the metal composite modified nano-zirconia catalyst prepared in this example is marked as 1% Zn-ZrO ₂ .

Example 3

A kind of preparation method of metal composite modified nano-zirconia catalyst of the present embodiment, described method is basically the same as embodiment 1, difference only is: the ZnO described in the step (4) of the present embodiment and ZrO ₂ nanopowder The mass ratio is 2:100. Therefore, correspondingly, the metal composite modified nano-zirconia catalyst prepared in this example is marked as 2% Zn-ZrO ₂ .

Example 4

A method for preparing a metal composite modified nano-zirconia catalyst of the present embodiment, the method comprises the following steps:

(1) Preparation of ZrO ₂ precursor

(a) Preparation of soluble zirconium salt solution: Weigh 17.1g of zirconium nitrate pentahydrate (Zr(NO ₃ ) ₄ 5H ₂ O), dissolve the weighed zirconium nitrate pentahydrate in 50mL deionized water, and Under the condition of /min, stir mechanically for 10min to obtain a soluble zirconium salt solution;

(b) Preparation of urea solution: Weigh 38.3g of urea ((NH ₂ ) ₂ CO) particles, dissolve the weighed urea in 100mL deionized water, and stir mechanically for 5min at a speed of 300rad/min to obtain urea solution;

(c) Mix the soluble zirconium salt solution obtained in step (a), the urea solution obtained in step (b), and 3 g of polyethylene glycol 600, and mechanically stir for 20 minutes under the condition of a rotating speed of 500 rad/min to obtain a homogeneous mixed solution 1; Add 3mL of hydrogen peroxide to the mixed solution 1, and continue to mechanically stir for 20min under the condition of a rotating speed of 500rad/min to completely dissolve it to obtain a uniform mixed solution 2; In a stainless steel reaction kettle lined with ethylene, seal it, raise the temperature of the reaction kettle to 150°C for a constant temperature hydrothermal reaction for 30 hours, after the reaction, cool to room temperature, alternately centrifuge and wash the obtained product twice, and place the obtained solid product in a Dry in an oven, the drying temperature is 40°C, and the drying time is 24h to obtain the ZrO ₂ precursor;

(2) Place the _ZrO2 precursor described in step (1) in a muffle furnace, and heat it up to 300°C for 8 hours at a constant temperature for calcination in an air atmosphere. After the calcination, white _ZrO2 powder is obtained;

(3) white ZrO powder described in step (2) is mixed with grinding aid isopropanol, and ground for 10 min to obtain ZrO _nano powder, the particle diameter of _the ZrO _nano powder is 30-80nm; wherein: The mass ratio of grinding aid to white _ZrO2 powder is 25:100.

(4) ZrO described in step (3) nanometer powder, CeO ₂ and dispersant are mixed, gained mixture is ground 30min, obtains _described metal composite modification nanometer zirconia catalyst, is marked as 1%Ce-ZrO ₂ ; Wherein: the dispersant is succinic acid; the added amount of the dispersant is 1% of the mass of the _ZrO2 nanometer powder; the mass ratio of the _CeO2 to the _ZrO2 nanometer powder is 1:100.

Example 5

A method for preparing a metal composite modified nano-zirconia catalyst of the present embodiment, the method comprises the following steps:

(1) Preparation of ZrO ₂ precursor

(a) Preparation of soluble zirconium salt solution: Weigh 30g of zirconium nitrate pentahydrate (Zr(NO ₃ ) ₄ 5H ₂ O), dissolve the weighed zirconium nitrate pentahydrate in 120mL deionized water, and Under the condition of min, stir mechanically for 3 min to obtain a soluble zirconium salt solution;

(b) Mix the soluble zirconium salt solution obtained in step (a), 150 mL of ammonia solution with a concentration of 6 mol/L, and 10 g of polyethylene glycol 600, and mechanically stir for 50 min at a speed of 500 rad/min to obtain a homogeneous mixture 1; then Add 10mL of hydrogen peroxide to the mixed solution 1, and continue to mechanically stir for 50min under the condition of a rotating speed of 500rad/min to completely dissolve it to obtain a homogeneous mixed solution 2; In a stainless steel reaction kettle lined with tetrafluoroethylene, seal it, raise the temperature of the reaction kettle to 200°C for a constant temperature hydrothermal reaction for 10 hours, after the reaction, cool to room temperature, and alternately centrifuge and wash the obtained product once, and the obtained solid The product was dried in an oven at a drying temperature of 150 ° C and a drying time of 8 hours to obtain a ZrO ₂ precursor;

(2) Place the _ZrO2 precursor described in step (1) in a muffle furnace, and heat it up to 700°C for 3h at a constant temperature for calcination in an air atmosphere. After the calcination, white _ZrO2 powder is obtained;

(3) White _ZrO2 powder described in step (2) is mixed with grinding aid 2-butanol, and ground for 10 min to obtain _ZrO2 nanometer powder, and the particle diameter of said _ZrO2 nanometer powder is 30～80nm; Wherein: The mass ratio of the grinding aid to the white _ZrO2 powder is 40:100.

(4) Mix _the ZrO nano powder, In ₂ O ₃ and dispersant in step (3), and grind the resulting mixture for 40 min to obtain the metal composite modified nano-zirconia catalyst, marked as 1% In-ZrO ₂ ; wherein: the dispersant is malonic acid; the addition of the dispersant is 2% of the mass of the ZrO ₂ nanometer powder; the mass ratio of the In ₂ O ₃ to the ZrO ₂ nanometer powder is 1:100.

Example 6

A method for preparing a metal composite modified nano-zirconia catalyst of the present embodiment, the method comprises the following steps:

(1) Preparation of ZrO ₂ precursor

(a) Preparation of soluble zirconium salt solution: Weigh 15g of zirconium nitrate pentahydrate (Zr(NO ₃ ) ₄ 5H ₂ O), dissolve the weighed zirconium nitrate pentahydrate in 90mL deionized water, and Under the condition of min, stir mechanically for 10 min to obtain a soluble zirconium salt solution;

(b) Mix the soluble zirconium salt solution obtained in step (a), 90 mL of hydrazine hydrate solution with a concentration of 5 moL/L, and 2 g of polyethylene glycol 600, and mechanically stir for 30 min at a speed of 500 rad/min to obtain a homogeneous mixture 1; Then add 5mL of hydrogen peroxide to the mixed solution 1, continue to mechanically stir for 30min under the condition of rotating speed 500rad/min, make it dissolve completely, and obtain the homogeneous mixed solution 2; In a polytetrafluoroethylene-lined stainless steel reaction kettle, seal it, raise the temperature of the reaction kettle to 170°C for a constant temperature hydrothermal reaction for 25 hours, after the reaction is completed, cool it to room temperature, alternately centrifuge and wash the obtained product twice, and the obtained The solid product was dried in an oven at a drying temperature of 80°C and a drying time of 10 hours to obtain a ZrO ₂ precursor;

(2) Place the ZrO ₂ precursor described in step (1) in a muffle furnace, and heat it up to 450° C. for calcination at a constant temperature in an air atmosphere for 5 hours. After the calcination is completed, a white ZrO ₂ powder is obtained;

(3) white ZrO powder described in step (2) is mixed with grinding aid isopropanol, and ground for 10 min to obtain ZrO _nano powder, the particle diameter of _the ZrO _nano powder is 30-80nm; wherein: The mass ratio of grinding aid to white _ZrO2 powder is 20:100.

(4) Mix the _ZrO nanometer powder, Y ₂ O ₃ and dispersant in step (3), grind the resulting mixture for 20 min to obtain the metal composite modified nano-zirconia catalyst, marked as 1% Y-ZrO ₂ ; wherein: the dispersant is glyceric acid; the added amount of the dispersant is 1% of the mass of the ZrO ₂ nanometer powder; the mass ratio of the Y ₂ O ₃ to the ZrO ₂ nanometer powder is 1:100.

Catalyst performance testing and characterization:

In order to make the catalyst react better and not block the reaction tube, the catalysts prepared in the above-mentioned Examples 1-6 of the present invention were made into catalyst particles of 20-40 mesh.

The present invention uses a miniature fixed-bed reactor to evaluate the catalyst, and the process conditions are 0.5-5mL of catalyst of 20-40 mesh, reaction temperature of 300-600°C, reaction pressure of 0.5-8MPa, raw material gas _H2 /CO=1 or 2, air The speed is 500～5000·h ^-1 .

For example, the performance evaluation of the catalyst prepared in Example 1 is carried out in a micro-fixed-bed reactor, and the specific operation steps are as follows: Weigh 1 mL of the metal composite modified nano-zirconia catalyst prepared in Example 1 and put it into the constant temperature zone in the middle of the reaction tube. Gas H ₂ /CO=2, temperature is 400°C, pressure is 3MPa, space velocity (GHSV) is 2000h ^-1 , after reaching a steady state, sampling and analysis are performed at intervals of 3h. Gas chromatography is used to conduct quantitative and qualitative analysis of raw gas and products. Using the methane correlation method in "Determination of H ₂ , N ₂ , CO, CO ₂ and C ₁ -C ₈ Hydrocarbons in Coal-based Fischer-Tropsch Synthesis Tail Gas and Gas Chromatography", the CO conversion rate and the material selectivity of each component were calculated.

Table 1 is a comparison table of the hydrogenation catalytic process parameters and performance test results of the metal composite modified nano-zirconia catalysts prepared in the above-mentioned Examples 1-5 of the present invention. It can be seen from Table 1 that the nano-zirconia catalyst modified by the metal Zn composite improves the conversion rate of CO, and in the product distribution, the _CO2 selectivity does not change significantly, maintaining at about 50%, and the hydrocarbon products change significantly. Among the metal composite modified nano-zirconia catalysts prepared in the various examples of the present invention, the 1% Zn- _ZrO catalyst prepared in Example 2 has the best catalytic CO hydrogenation performance, the selectivity of low-carbon olefins is as high as 75.1%, and C ₄ olefins The proportion of isobutene is 96.7%, and the olefin ratio (O/P) is 8.8.

Table 1 Comparison Table of Process Parameters and Performance Test Results of Metal Composite Modified Nano-zirconia Catalysts for Hydrogenation Catalysts Prepared in Examples 1-5

Claims (4)

1. The application of a metal composite modified nano-zirconia catalyst in the preparation of low-carbon olefins by catalytic CO hydrogenation, characterized in that: the preparation method of the catalyst specifically comprises the following steps: (1) Mix soluble zirconium salt solution, alkali solution, and surfactant according to the proportioning ratio, and stir evenly to obtain a mixed solution 1; then add hydrogen peroxide to the mixed solution 1, and continue to stir evenly to obtain a mixed solution 2; The mixed solution 2 is transferred to a hydrothermal reaction kettle, sealed, and the reaction kettle is heated to 150-200° C. for constant temperature hydrothermal reaction for 10-30 hours. After the reaction is completed, it is cooled to room temperature, and the obtained product is centrifuged, washed, and dried. Obtain ZrO _precursor ; Wherein: the mass ratio of the soluble zirconium salt in the described soluble zirconium salt solution, the alkali in the alkali solution, surfactant three is (15～30):(20～60):(1～ 10); The surfactant is polyethylene glycol 600; (2) Place the ZrO ₂ precursor described in step (1) in a muffle furnace, and heat it up to 300-700°C for 3-8 hours in an air atmosphere, and then calcinate at a constant temperature for 3-8 hours. After the calcination, white ZrO ₂ powder is obtained; (3) the white _ZrO powder described in step (2) is mixed with an appropriate amount of grinding aid, and ground for 10 to 40 min to obtain ZrO _nano powder; (4) Mixing the _ZrO nanopowder described in step (3) with the metal oxide M _x O _y according to the proportioning ratio, and grinding the resulting mixture for 10 to 40 minutes to obtain the metal composite modified nano-zirconia catalyst; wherein: The metal oxide M _x O _y is any one of ZnO, CeO ₂ , Y ₂ O ₃ , In ₂ O ₃ ; the mass ratio of the metal oxide M _x O _y to ZrO ₂ nanopowder is 0.5-2 : 100; the mixture also includes a dispersant, the dispersant is a polycarboxylic acid, and the polycarboxylic acid is selected from any one of oxalic acid, malonic acid, malonic acid, succinic acid, adipic acid or more. 2. application according to claim 1, is characterized in that: in the soluble zirconium salt solution described in step (1), solute is soluble zirconium salt, and solvent is any one in deionized water, ethanol, acetone; Wherein : The soluble zirconium salt is any one of zirconium nitrate pentahydrate, zirconyl nitrate, zirconium chloride, zirconium acetate, zirconium citrate, and zirconium n-propoxide. 3. The application according to claim 1, characterized in that: the alkaline solution in step (1) is any one or more of urea solution, ammonia solution or hydrazine hydrate solution. 4. The application according to claim 1, characterized in that the mass ratio of the grinding aid to the white _ZrO2 powder in step (3) is 20-40:100.