CN113058583A

CN113058583A - GaZrOxPreparation method and application of bimetallic oxide solid solution catalyst

Info

Publication number: CN113058583A
Application number: CN202110323164.8A
Authority: CN
Inventors: 吴剑峰; 冯文华; 苗宇婷; 于明明
Original assignee: Lanzhou University
Current assignee: Lanzhou University
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2021-07-02
Anticipated expiration: 2041-03-26
Also published as: CN113058583B

Abstract

The invention provides a carbon dioxide (CO)₂) High-efficiency synthesis of methanol and dimethyl ether GaZrO by hydrogenation_x(Y%) preparation method and application of bimetallic solid solution catalyst, Y represents n_Ga/(n_Ga+n_Zr) The numerical value of (c). The catalyst is prepared by a method of solvent volatilization induced self-assembly (EISA) by taking Ga and Zr as metal sources and taking a block copolymer as a template agent. Said GaZrO_xBimetallic oxide solid solution catalystThe agent can be used in CO₂The reaction for preparing the methanol and the dimethyl ether by hydrogenation is carried out at 3MPa, 603K and 24000 ml/(g)_catH) under conditions of CO₂The conversion per pass is over 9.0%, the selectivity of methanol and dimethyl ether reaches 72.7%, and the space-time yield of methanol and dimethyl ether is 0.61g_{(methanol+DME)}/(g_catH). The catalyst prepared by the method has better activity than the catalyst prepared by the traditional coprecipitation method under the same condition. In addition, the catalyst also has the characteristics of sintering resistance, good stability and the like.

Description

GaZrOxPreparation method and application of bimetallic oxide solid solution catalyst

Technical Field

The invention belongs to the technical field of catalytic hydrogenation, and particularly relates to a catalyst for adding carbon dioxidePreparation of methanol and dimethyl ether GaZrO from hydrogen_xA preparation method and application of a bimetallic oxide solid solution catalyst.

Background

Carbon dioxide (CO)₂) The dramatic increase in emission has had a serious impact on the human living environment and global climate, and in recent years CO has been a major concern₂The emission reduction and the effective utilization of the carbon dioxide cause high attention of countries all over the world. At present, CO₂This can be reduced in three ways: control of CO₂Emission of CO₂Capture and storage of CO₂Chemical transformation and utilization of. Methanol and dimethyl ether are not only important platform molecules, which can be further converted into fuels and valuable chemicals, but also can be used as hydrogen storage compounds. Thus, CO is converted₂As a carbon source, the catalytic hydrogenation for preparing the methanol and the dimethyl ether can realize the sustainable utilization of resources.

From CO₂And H₂The synthesis of methanol mainly comprises the following reactions: (1) and (3) synthesis of methanol:

(ΔrH_{298 K}＝-49.5kJ mol^-1)，

(ΔrH_{298 K}＝-90.5kJ mol^-1) (ii) a (2) Reverse water gas shift Reaction (RWGS):

(ΔrH_{298 K}＝41.2kJ mol^-1). Methanol synthesis is an exothermic reaction, while the side reaction RWGS is an endothermic reaction. With increasing temperature, there is a competing relationship between methanol synthesis and the RWGS reaction. At the same time, the water produced in the two reactions accelerates the sintering of the active sites in the catalyst, which leads to the deactivation of the catalyst. In addition, CO₂Thermodynamic stability and kinetic inertness (Δ G)_f＝-394.4kJ mol^-1) And also a barrier to methanol synthesis. Therefore, the design can promote CO at low temperature₂The activation of the molecule and the catalyst system capable of preventing the formation of by-products are important indexes of the high-efficiency methanol synthesis catalyst.

CO₂Catalysts for the hydro-synthesis of methanol can be generally classified into three types: (1) a copper-based catalyst for preparing methanol from synthetic gas is prepared from ZnO and ZrO₂、CeO₂、Al₂O₃、SiO₂Carbon nanofibers, graphene, MOFs, and the like. Copper-based catalysts are widely used in the reaction for preparing methanol due to low cost, but the formation of water as a by-product promotes catalyst agglomeration and oxidation of active copper, thereby causing severe deactivation of the catalyst (university of continental project patent CN 101513615A, shanxi coal chemical institute patent CN 103263926A, rake science limited patent CN 104383928A; shanghai friendship patent CN 102580750 a, rake science limited patent CN 102240553A, xiamen university patent CN 101786001 a, shanghai high research institute patent CN 103272607 a); (2) noble metal-based catalysts such as Pd, Au, Pt, Ag, etc. Although noble metal-based catalysts exhibit high activity, the preparation cost is high; (3) bimetallic catalysts, mainly including alloys (such as Rh-W, Pd-Ga, Pt-Co, Pd-Zn, etc.), intermetallic compounds (such as Pd-Ga, Pd-Zn, Pd-In, Ni-Ga, etc.), and metal oxide catalysts (Dazhuan chemico-physical research institute patent CN 109420484A). Based on the problems of the above copper-based catalyst and noble metal-based catalyst, for CO₂The high activity bimetallic oxide catalyst for synthesizing methanol and dimethyl ether by hydrogenation is produced, but the current preparation method is mostly limited to coprecipitation method, and high activity CO is still lacked₂A catalyst for preparing methanol and dimethyl ether by hydrogenation.

Disclosure of Invention

The invention provides GaZrO used for synthesizing methanol and dimethyl ether by carbon dioxide hydrogenation_xThe preparation method of the bimetallic solid solution catalyst has the advantages of high activity, good stability, difficult inactivation and the like.

The GaZrO used for synthesizing methanol and dimethyl ether by hydrogenating carbon dioxide_xThe preparation method of the bimetallic solid solution catalyst is characterized by comprising the following steps: respectively preparing Ga and Zr metal salt alcohol solutions, wherein the molar loading of metal Ga is more than or equal to 5 percent and less than or equal to 36 percent, and the total molar quantity of metal ions is10-50 mmol; preparing 1-5g of template alcohol solution, wherein the mass concentration of the template is 0.01-0.5g/g_Alcohol(s)(ii) a The three are continuously stirred for 12 to 24 hours at the temperature of 293K to 313K; the mixing mode comprises that the template agent alcoholic solution is dripped into the metal salt alcoholic solution, the metal salt alcoholic solution is dripped into the template agent alcoholic solution or the two are mixed in a parallel flow way; continuously stirring for 2-24h at the temperature of 293K-313K after mixing; transferring the solution into a borosilicate culture dish, and placing the borosilicate culture dish in a fume hood to stand still for 2-7 days to evaporate the solvent; the obtained gel is calcined in flowing air at 673K-873K for 3-10 h.

Further, the Ga salt is one or more than two of chloride, nitrate, acetate and sulfate; the Zr salt is one or more than two of chloride, nitrate, acetate, sulfate, zirconyl nitrate, zirconium oxychloride and zirconium isopropoxide; the template agent is one or more than two of P123, F127, P84, P104, F108 and P105 block copolymers; the alcoholic solution is C₁-C₁₀One or more than two of alcohol.

Further, the calcination atmosphere may be one or more of air, oxygen, nitrogen, and helium.

The resulting GaZrO_x(7, 19, 25, 27, 36%) the catalyst was in a solid solution structure, exhibiting Ga incorporated in ZrO₂The structural features of the crystal lattice of (1) are shown in figure 3.

Meanwhile, the invention also provides GaZrO prepared by the preparation method_xUse of a bimetallic solid solution catalyst, GaZrO_xThe bimetallic solid solution catalyst can be applied to the synthesis of methanol and dimethyl ether by the hydrogenation of carbon dioxide, and the application steps are as follows:

the activity evaluation of the catalyst on the reaction of synthesizing methanol and dimethyl ether by hydrogenating carbon dioxide is carried out on a pressurized fixed bed continuous flow reactor-gas chromatography combined system. Before reaction, the catalyst is activated for 1-12h at 473K-673K by one or two of pure hydrogen, argon and nitrogen. The conditions for synthesizing the methanol and the dimethyl ether by hydrogenating the carbon dioxide are as follows: the pressure of the raw material gas is 1-20MPa, the reaction temperature is 513K-673K, and the space velocity is 6000-_cat·h)，n(H₂)：n(CO₂) 1-30. The reaction products were separated and identified using an on-line gas chromatograph equipped with a Thermal Conductivity Detector (TCD) and a hydrogen Flame Ionization Detector (FID). Capillary chromatography columns (Agilent HP-Plot Q, 30m x 0.53mm x 40 μm) attached to FID were used for analysis of hydrocarbons, alcohols and other carbonaceous products. A packed column (Torilong information technology Co., Lanzhou, TDX-01, 2 m.times.3 mm) connected to a TCD was analyzed for other gaseous products (Ar, CO, CH)₄And CO₂). The line between the reactor and the valve was heated to 373K-433K to prevent condensation of the product. CH (CH)₄As a bridge between FID and TCD for quantitative analysis of the product.

The invention develops a GaZrO prepared by a solvent evaporation induction self-assembly method_xPreparation method of bimetallic oxide solid solution catalyst and GaZrO prepared by preparation method_xThe bimetallic oxide solid solution catalyst can be used for the reaction of preparing methanol and dimethyl ether by carbon dioxide hydrogenation. The catalyst prepared by the method has better activity than the catalyst prepared by the traditional coprecipitation method under the same condition. In addition, the catalyst prepared by the preparation method provided by the invention has the characteristics of sintering resistance, good stability and the like.

The catalyst prepared by the preparation method can effectively convert carbon dioxide into methanol and dimethyl ether, the optimal reaction temperature is 603-623K, and the catalyst is anti-sintering and good in stability. At 3MPa, 603K, 24000 ml/(g)_catH) of CO₂The conversion per pass exceeded 9.0%, the selectivity for methanol and dimethyl ether reached 72.7%, and the space-time yield of methanol and dimethyl ether was 0.61g_{(methanol+DME)}/(g_cat·h)。

Drawings

FIG. 1: GaZrO_x(27%) 100h long-range stability of the catalyst. T603K, P3.0 MPa, H₂/CO₂＝3/1，GHSV＝24,000ml/(g_cat·h)。

FIG. 2: preparation of GaZrO by EISA method and coprecipitation method_xAnd (3) comparing the carbon dioxide hydrogenation catalytic performances of the catalysts. Reaction conditions are as follows: T513-653K, P3.0 MPa, H₂/CO₂＝3/1，GHSV＝24,000ml/(g_cat·h)。

FIG. 3:ZrO₂，GaZrO_x(7, 19, 25, 27, 36%) and Ga₂O₃Powder X-ray diffraction pattern of the catalyst. Symbols (. circle.) and (. circle.) denote tetragonal phase and monoclinic phase ZrO, respectively₂。

Detailed Description

Example 1

1g of triblock copolymer P-123, 10mmol of ZrCl₄Dissolved in two beakers containing 10g of ethanol, respectively, and stirred at room temperature for 12 h. The two solutions were mixed and stirring was continued at room temperature for 2 h. The resulting solution was transferred to a borosilicate petri dish and placed in a fume hood for 3-5 days, and the solvent was evaporated. The dried gel was calcined in flowing air (10ml/min) at a heating rate of 1K/min at 773K for 5h and the resulting catalyst was recorded as: ZrO (ZrO)₂. Tabletting, crushing, and screening 230-400 μm for catalytic evaluation.

0.3g of the sieved catalyst was diluted with 0.7g of quartz sand, placed in a constant temperature place of a reaction tube, and fixed up and down with glass wool. At 613K, flowing H₂(30std ml/min, atmospheric pressure) for 2 hours, followed by cooling to the desired reaction temperature. Mixing the gas mixture V (H)₂)：V(CO₂): v (ar) ═ 72: and (3) introducing the mixture into a reaction tube through a mass flow meter, wherein the reaction conditions are as follows: 3MPa, 513-653K, GHSV 24,000 ml/(g)_catH). The catalyst evaluation results are shown in Table 1.

Example 2

The metal salt used for the preparation of the catalyst is 10mmol GaCl₃The other catalyst preparation steps were the same as in example 1, and the resulting catalyst was noted as: ga₂O₃. The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 3

The catalysts of example 1 and example 2 are used as per n_Ga/(n_Ga+n_Zr) The resulting catalyst was physically mixed in a ratio of 0.27 and reported as: ga₂O₃ +ZrO₂. The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 4

1g of triblock copolymer P-123, 0.65mmol of GaCl₃And 9.35mmol of ZrCl₄Dissolved in three beakers containing 10g of ethanol, respectively, and stirred at room temperature for 12 h. The three solutions were mixed and stirring was continued at room temperature for 2 h. The other catalyst preparation steps were the same as in example 1, and the resulting catalyst was noted as: GaZrO_x(7%). The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 5

The metal salt used for the catalyst preparation was 1.89mmol GaCl₃And 8.11mmol of ZrCl₄The other catalyst preparation steps were the same as in example 1, and the resulting catalyst was noted as: GaZrO_x(19%). The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 6

The metal salt used for the preparation of the catalyst was 2.50mmol of GaCl₃And 7.50mmol of ZrCl₄The other catalyst preparation steps were the same as in example 1, and the resulting catalyst was noted as: GaZrO_x(25%). The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 7

The metal salt used for the catalyst preparation was 2.70mmol GaCl₃And 7.30mmol of ZrCl₄The other catalyst preparation steps were the same as in example 1, and the resulting catalyst was noted as: GaZrO_x(27%). The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1. In addition, when T is 603K, P is 3.0MPa, H₂/CO₂＝3/1，GHSV＝24,000ml/(g_catH) for 100 hours, the catalyst shows no deactivation and a certain stability. The results are shown in FIG. 1.

Example 8

The metal salt used for the catalyst preparation was 3.60mmol GaCl₃And 6.40mmol of ZrCl₄The other catalyst preparation steps were the same as in example 1, and the resulting catalyst was noted as: GaZrO_x(36%). Catalyst and process for preparing sameThe evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1.

Example 9

3mmol of Ga (NO) are weighed₃)₃·9H₂O and 8mmol of Zr (NO)₃)₄·5H₂O, dissolved in 100ml of deionized water. 31.22mmol (NH) were stirred vigorously at 343K₄)₂CO₃The aqueous solution was added dropwise to the above metal salt solution at a rate of 3 ml/min. The product was cooled to room temperature after aging for 2h at 343K. Suction filtration, washing with deionized water for 3-4 times, and drying at 383K for 4 h. Finally calcined in flowing air (10ml/min) at a heating rate of 1K/min for 3h at 773K, and the catalyst obtained is noted: GaZrO_x(27%) (coprecipitation method). The catalyst evaluation procedure and reaction conditions were the same as in example 1, and the catalyst evaluation results are shown in Table 1 and FIG. 2.

Example 10

The catalyst preparation procedure was the same as in example 6. The reaction conditions in the catalyst evaluation step were changed to: 2MPa, 513-653K, GHSV 24,000 ml/(g)_catH). The catalyst evaluation results are shown in Table 1.

Example 11

The catalyst preparation procedure was the same as in example 6. The reaction conditions in the catalyst evaluation step were changed to: 4MPa, 513 charge 653K, GHSV 24,000 ml/(g)_catH). The catalyst evaluation results are shown in Table 1.

Table 1: GaZrO of different metal ratios_xCatalyst, different preparation methods and catalytic evaluation results under different reaction pressures. Reaction conditions are as follows: 603K, n (H)₂)/n(CO₂)＝3∶1。

As can be seen from Table 1, pure Ga₂O₃Methanol synthesis activity ratio of catalyst pure ZrO₂The catalyst was slightly higher. GaZrO_x(7, 19, 25, 27, 36%) bimetallic oxide solid solution catalyst for the synthesis of methanol and dimethyl ether with (Ga)₂O₃+ZrO₂) The physically mixed catalyst was more active than the other, indicating that there was a strong synergy between Zr and Ga. Wherein the GaZrO_x(27%) catalyst in CO₂The best performance is shown in the hydrogenation reaction: at 3MPa, 603K, 24000mL g_cat ^-1h^-1Under reaction conditions of (1), GaZrO_x(27%) the catalyst had 9.02% CO₂Conversion, methanol and dimethyl ether selectivity of 72.73%, and 0.61g_{(methanol+DME)}/(g_catH) space-time yields of methanol and dimethyl ether. Furthermore, as the pressure increased from 2MPa to 4MPa, CO₂The conversion rate is increased sharply, the selectivity of the methanol and the dimethyl ether is increased slightly, and the space-time yield can reach 0.76g_{(methanol+DME)}/(g_catH). Further, GaZrO prepared by the EISA method under the same reaction conditions as compared with the co-precipitation method_x(27%) the catalyst exhibited better CO₂Activity of hydrogenation for preparing methanol and dimethyl ether (figure 2).

Claims

1. GaZrO_xThe preparation method of the bimetallic oxide solid solution catalyst is characterized in that a solvent volatilization induced self-assembly method is adopted, and the preparation method comprises the following steps:

respectively preparing Ga and Zr metal salt alcohol solutions, wherein the molar loading of metal Ga is more than or equal to 5 percent and less than or equal to 36 percent of Ga/(Ga + Zr), and the total molar quantity of metal ions is 10-50 mmol; preparing 1-5g of template alcohol solution, wherein the mass concentration of the template is 0.01-0.5g/g_Alcohol(s)(ii) a The three are continuously stirred for 12 to 24 hours at the temperature of 293K to 313K; the mixing mode comprises that the template agent alcoholic solution is dripped into the metal salt alcoholic solution, the metal salt alcoholic solution is dripped into the template agent alcoholic solution or the two are mixed in a parallel flow way; continuously stirring for 2-24h at the temperature of 293K-313K after mixing; transferring the solution into a borosilicate culture dish, and placing the borosilicate culture dish in a fume hood to stand still for 2-7 days to evaporate the solvent; the obtained gel is calcined in flowing air at 673K-873K for 3-10 h.

2. GaZrO according to claim 1_xProcess for the preparation of a bimetallic oxide solid solution catalystCharacterized in that: the Ga metal salt is one or more than two of chloride, nitrate, acetate and sulfate;

the Zr metal salt is one or more than two of chloride, nitrate, acetate, sulfate, zirconyl nitrate, zirconium oxychloride and zirconium isopropoxide;

the template agent is one or more than two of P123, F127, P84, P104, F108 and P105 block copolymers;

the alcoholic solution is C₁-C₁₀One or more than two of alcohol.

3. A GaZrO according to claim 1_xThe preparation method of the bimetallic oxide solid solution catalyst is characterized by comprising the following steps: the calcining atmosphere is one or more of air, oxygen and nitrogen.

4. A GaZrO process as claimed in any of claims 1 to 3_xPreparation method of bimetallic oxide solid solution catalyst and GaZrO prepared by preparation method_xThe bimetallic oxide solid solution catalyst is applied to the synthesis of methanol and dimethyl ether by the hydrogenation of carbon dioxide.

5. GaZrO according to claim 4_xThe application of the bimetallic oxide solid solution catalyst is characterized by comprising the following steps: the reaction for synthesizing the methanol and the dimethyl ether by the hydrogenation of the carbon dioxide is carried out on a pressurized fixed bed continuous flow reactor, and the reaction conditions are as follows: the pressure of the raw material gas is 1-20MPa, the reaction temperature is 513K-673K, and the space velocity is 6000-_cat·h)，n(H₂)∶n(CO₂)＝1-30。

6. GaZrO according to claim 4 or 5_xThe application of the bimetallic oxide solid solution catalyst is characterized in that the catalyst is activated before being applied, and the activation conditions are as follows: activating at 473K-673K with one or two of pure hydrogen, argon, nitrogen and helium for 1-12 h.

7. GaZrO according to claim 5_xThe application of the bimetallic oxide solid solution catalyst is characterized in that: the bimetallic oxide solid solution catalyst is applied to the reaction of preparing methanol and dimethyl ether by carbon dioxide hydrogenation, the reaction pressure is 3MPa, the reaction temperature is 603K, and the airspeed is 24000 ml/(g)_catH) feed gas n (H)₂)∶n(CO₂)＝3∶1。

8. GaZrO according to claim 5_xThe application of the bimetallic oxide solid solution catalyst is characterized in that the obtained catalyst is tableted and crushed, and 180-800 mu m is screened for evaluation.