Bifunctional catalyst as well as preparation method and application thereof

Abstract

The invention discloses a bifunctional catalyst as well as a preparation method and application thereof, and belongs to the technical field of catalyst preparation. The bifunctional catalyst comprises a carrier and an active component, the carrier comprises CeO2; ceO2 has oxygen vacancy; the active component comprises Pd. The bifunctional catalyst has high reaction activity for catalyzing one-step synthesis of methyl isobutyl ketone from acetone in application, the conversion rate of acetone reaches 47%, the selectivity of methyl isobutyl ketone is 96% or above, and the bifunctional catalyst has high stability and is suitable for industrial production of one-step synthesis of methyl isobutyl ketone from acetone.

Description

Technical Field

[0001] This application relates to a bifunctional catalyst, its preparation method, and its application, belonging to the field of catalyst preparation technology. Background Technology

[0002] Methyl isobutyl ketone (MIBK) is an excellent medium-boiling-point solvent and separating agent, as well as a raw material for organic synthesis. In coatings, MIBK can form various mixed solvents with other solvents, allowing for the adjustment of solvent solubility and evaporation rate, thereby improving coating performance. As a coating solvent, MIBK not only increases the leveling properties of the paint film but also enhances its gloss, and it is widely used in wire and cable, magnetic tape, automotive, shipbuilding, aerospace, and home decoration industries. Due to the huge market demand and wide range of applications for MIBK, its efficient production has become a research hotspot. Research on green synthesis processes for MIBK is of great significance for improving atom economy, breaking through international technological barriers, and meeting domestic market demand.

[0003] Major international chemical companies utilize a one-step process to produce methyl isobutyl ketone (Methyl Iobutyl ketone) from acetone, employing Pd / resin catalysts. Methyl Iobutyl ketone is obtained from acetone through liquid-phase condensation, dehydration, and selective hydrogenation. Among these, a US company's Pd / resin catalyst exhibits good temperature resistance and a wide range of process flexibility, facilitating stable operation of the entire production unit; however, the preparation cost of Pd / resin catalysts is relatively high. Patent CN1101269C discloses a resin-supported catalyst for the synthesis of Methyl Iobutyl ketone, but the reaction temperature is limited to 110-120°C. After a reaction time exceeding 500 hours, the conversion rate decreases from 47% to 36%, still exhibiting traditional deactivation characteristics. Summary of the Invention

[0004] To address the aforementioned technical problems of poor catalytic performance and low stability of catalysts, the bifunctional catalyst prepared by the technical solution provided in this application can be applied to the one-step preparation of methyl isobutyl ketone from acetone, exhibiting excellent catalytic performance, stability, and promising industrial application prospects.

[0005] According to a first aspect of this application, a bifunctional catalyst is provided, the bifunctional catalyst comprising a support and an active component; The carrier includes CeO2; The CeO2 has oxygen vacancies; The active component includes Pd.

[0006] Optionally, the carrier is modified with a modifying agent; The modifying agent includes transition metal oxides.

[0007] Optionally, the transition metal oxide is selected from WOx.

[0008] Optionally, based on the mass percentage of the bifunctional catalyst, the content of the modifying agent is 0.2-5%, and the content of the active component is 0.2-1%.

[0009] Optionally, the bifunctional catalyst was characterized by XPS. In the CeO2-O1s spectrum, the values ​​of lattice oxygen Lo (529.5±0.3 eV), oxygen vacancy Vo (530.8±0.3 eV), and chemisorbed oxygen Co (533.1±0.3 eV) were obtained.

[0010] According to a second aspect of this application, a method for preparing a bifunctional catalyst is provided, comprising the following steps: S1. Obtain CeO2 support I with oxygen vacancies; S2. Mix the aqueous solution containing the modification agent precursor with the CeO2 support I to obtain a suspension. Shake and impregnate the suspension until dry to obtain a solid. Grind the solid into powder and calcine to obtain catalyst support II. S3. Mix an aqueous solution containing palladium source with the catalyst support II in equal volume, evaporate the water, dry and calcine, and reduce in a reducing atmosphere to obtain the bifunctional catalyst.

[0011] Optionally, in S1, the method for preparing the CeO2 support I with oxygen vacancies includes the following steps: An aqueous solution containing Ce(NO3)3 is mixed with alkaline solution I to obtain mixed solution I. After aging, a cerium hydroxide precursor is obtained. The precursor is then calcined under an H2 / Ar atmosphere to obtain the CeO2 support I with oxygen vacancies.

[0012] Optionally, the alkaline solution I is selected from an aqueous solution of at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia.

[0013] Optionally, the pH value of the mixed solution I is 8-9.

[0014] Optionally, the aging conditions include: a temperature of 90~95 ℃ and a reaction time of 12~24 h under stirring.

[0015] Optionally, the calcination conditions include: an atmosphere of 10-100% H2 / Ar, a temperature of 800-1000 ℃, and a time of 4-6 h.

[0016] Optionally, in S2, when the modifying agent is WOx, the corresponding modifying agent precursor is ammonium metatungstate.

[0017] Optionally, in S2, the calcination conditions include: an air atmosphere, a temperature of 800~1000 ℃, and a time of 2~4 h.

[0018] Optionally, in S3, the palladium source is selected from at least one of palladium nitrate and palladium chloride.

[0019] According to a third aspect of this application, a bifunctional catalyst is provided for the one-step catalytic preparation of methyl isobutyl ketone from acetone.

[0020] Optionally, the one-step catalytic preparation of methyl isobutyl ketone from acetone is carried out in a fixed-bed reactor.

[0021] The beneficial effects that this application can produce include: The bifunctional catalyst provided in this application is synthesized via co-precipitation and then calcined at high temperature under a reducing atmosphere to form an oxygen-vacancy-rich cerium oxide (CeO2) support on which the active component is loaded. Simultaneously, the modification with transition metal oxides significantly enhances the surface acidity of the catalyst and the stability of the reduced active metal, ultimately forming a catalytic structure with both dehydration and hydrogenation functions. In application, the bifunctional catalyst exhibits high activity for the one-step synthesis of methyl isobutyl ketone from acetone, achieving an acetone conversion of 47% and a methyl isobutyl ketone selectivity exceeding 96%. Furthermore, the bifunctional catalyst possesses high stability, making it suitable for the industrial production of methyl isobutyl ketone via the one-step synthesis of acetone. The reaction can also co-produce isopropanol and diisobutyl ketone (DIBK), demonstrating high economic value. Attached Figure Description

[0022] Figure 1 This is an XPS characterization image of the bifunctional catalyst in Example 1 of this application. Detailed Implementation

[0023] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0024] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased through commercial channels.

[0025] Unless otherwise specified, all test methods are conventional and all instrument settings are those recommended by the manufacturer.

[0026] Example 1 100 g of deionized water was added to a 1 L reactor. 100 g of a 30 wt% cerium nitrate solution and 30 mL of a 25 wt% NH4OH solution were added dropwise to the reactor, maintaining the pH at 8-9. After the addition was complete, the temperature was raised to 85 °C, and the mixture was stirred and aged for 8 h to obtain a suspension of cerium hydroxide. After centrifugation and two washes with pure water, the suspension was dried at 120 °C to obtain a white powder. The cerium hydroxide solid was then heated at 800 °C under a 10% H2 / Ar atmosphere. oCeO2 support I was obtained by calcination at C for 5 h. 10 g of ammonium metatungstate aqueous solution (0.5 wt% W) was prepared, and 10 g of CeO2 support I was added. The mixture was ultrasonically dispersed until homogeneous, and the suspension was shaken and impregnated in an 80 ℃ constant-temperature shaker until dry. The resulting solid was ground into powder and calcined in a muffle furnace at 800 ℃ for 180 min to obtain a series of 0.5%WOx-CeO2 catalyst supports II. 20 g of palladium nitrate aqueous solution (0.1 wt% Pd) was weighed, and 10 g of 0.5%WOx-CeO2 catalyst support II was added. After ultrasonic dispersion, the mixture was evaporated to dryness under slight negative pressure in a rotary evaporator. After drying and calcination, the solid catalyst was reduced at 300 ℃ in a hydrogen atmosphere to obtain a bifunctional catalyst 0.2%Pd-0.5%WOx-CeO2 for the synthesis of methyl isobutyl ketone. The bifunctional catalyst was characterized by XPS. Figure 1 As shown, the CeO2-O1s spectrum contains lattice oxygen Lo (529.5 eV), oxygen vacancies Vo (530.8 eV), and chemisorbed oxygen Co (533.1 eV), indicating that CeO2 has an abundant oxygen vacancy structure.

[0027] Example 2 100 g of deionized water was added to a 1 L reactor. 100 g of a 30 wt% cerium nitrate solution and 30 mL of a 25 wt% NH4OH solution were added dropwise to the reactor, maintaining the pH at 8-9. After the addition was complete, the temperature was raised to 85 °C, and the mixture was stirred and aged for 8 h to obtain a suspension of cerium hydroxide. After centrifugation and two washes with pure water, the suspension was dried at 120 °C to obtain a white powder. The cerium hydroxide solid was then heated at 800 °C under a 10% H2 / Ar atmosphere. o CeO2 support I was obtained by calcination at C for 5 h. 10 g of an aqueous solution of ammonium metatungstate (1 wt% W) was prepared, and 10 g of CeO2 support I was added. The mixture was ultrasonically dispersed until homogeneous, and the suspension was shaken and impregnated in an 80 °C constant-temperature shaker until dry. The resulting solid was ground into powder and calcined in a muffle furnace at 800 °C for 180 min to obtain a series of 0.5% WOx-CeO2 catalyst supports II. 20 g of an aqueous solution of palladium nitrate (0.1 wt% Pd) was weighed, and 10 g of 0.5% WOx-CeO2 catalyst support II was added. After ultrasonication until homogeneous dispersion, the mixture was evaporated to dryness under slight negative pressure in a rotary evaporator. After drying and calcination, the solid catalyst was reduced at 300 °C in a hydrogen atmosphere to obtain a bifunctional catalyst 0.2% Pd-1% WOx-CeO2 for the synthesis of methyl isobutyl ketone. The XPS characterization of this bifunctional catalyst was similar to that in Example 1.

[0028] Example 3 100 g of deionized water was added to a 1 L reactor. 100 g of a 30 wt% cerium nitrate solution and 30 mL of a 25 wt% NH4OH solution were added dropwise to the reactor, maintaining the pH at 8-9. After the addition was complete, the temperature was raised to 85 °C, and the mixture was stirred and aged for 8 h to obtain a suspension of cerium hydroxide. After centrifugation and two washes with pure water, the suspension was dried at 120 °C to obtain a white powder. The cerium hydroxide solid was then heated at 800 °C under a 10% H2 / Ar atmosphere. o CeO2 support I was obtained by calcination at C for 5 h. 10 g of an aqueous solution of ammonium metatungstate (3 wt%) was prepared, and 10 g of CeO2 support I was added. The mixture was ultrasonically dispersed until homogeneous, and the suspension was shaken and impregnated in an 80 °C constant-temperature shaker until dry. The resulting solid was ground into powder and calcined in a muffle furnace at 800 °C for 180 min to obtain a series of 0.5% WOx-CeO2 catalyst supports II. 20 g of an aqueous solution of palladium nitrate (0.1 wt%) was weighed, and 10 g of 0.5% WOx-CeO2 catalyst support II was added. After ultrasonication until homogeneous dispersion, the mixture was evaporated to dryness under slight negative pressure in a rotary evaporator. After drying and calcination, the solid catalyst was reduced at 300 °C in a hydrogen atmosphere to obtain a bifunctional catalyst 0.2% Pd-3% WOx-CeO2 for the synthesis of methyl isobutyl ketone. The XPS characterization of this bifunctional catalyst was similar to that in Example 1.

[0029] Example 4 100 g of deionized water was added to a 1 L reactor. 100 g of a 30 wt% cerium nitrate solution and 30 mL of a 25 wt% NH4OH solution were added dropwise to the reactor, maintaining the pH at 8-9. After the addition was complete, the temperature was raised to 85 °C, and the mixture was stirred and aged for 8 h to obtain a suspension of cerium hydroxide. After centrifugation and two washes with pure water, the suspension was dried at 120 °C to obtain a white powder. The cerium hydroxide solid was then heated at 800 °C under a 10% H2 / Ar atmosphere. oCeO2 support I was obtained by calcination at C for 5 h. 10 g of an aqueous solution of ammonium metatungstate (5 wt%) was prepared, and 10 g of CeO2 support I was added. The mixture was ultrasonically dispersed until homogeneous, and the suspension was shaken and impregnated in an 80 °C constant-temperature shaker until dry. The resulting solid was ground into powder and calcined in a muffle furnace at 800 °C for 180 min to obtain a series of 0.5% WOx-CeO2 catalyst supports II. 20 g of an aqueous solution of palladium nitrate (0.1 wt%) was weighed, and 10 g of 0.5% WOx-CeO2 catalyst support II was added. After ultrasonication until homogeneous dispersion, the mixture was evaporated to dryness under slight negative pressure in a rotary evaporator. After drying and calcination, the solid catalyst was reduced at 300 °C in a hydrogen atmosphere to obtain a bifunctional catalyst 0.2% Pd-5% WOx-CeO2 for the synthesis of methyl isobutyl ketone. The XPS characterization of this bifunctional catalyst was similar to that in Example 1.

[0030] Example 5 100 g of deionized water was added to a 1 L reactor. 100 g of a 30 wt% cerium nitrate solution and 30 mL of a 25 wt% NH4OH solution were added dropwise to the reactor, maintaining the pH at 8-9. After the addition was complete, the temperature was raised to 85 °C, and the mixture was stirred and aged for 8 h to obtain a suspension of cerium hydroxide. After centrifugation and two washes with pure water, the suspension was dried at 120 °C to obtain a white powder. The cerium hydroxide solid was then heated at 800 °C under a 10% H2 / Ar atmosphere. o CeO2 support I was obtained by calcination at C for 5 h. 10 g of an aqueous solution of ammonium metatungstate (3 wt%) was prepared, and 10 g of CeO2 support I was added. The mixture was ultrasonically dispersed until homogeneous, and the suspension was shaken and impregnated in an 80 °C constant-temperature shaker until dry. The resulting solid was ground into powder and calcined in a muffle furnace at 800 °C for 180 min to obtain a series of 0.5% WOx-CeO2 catalyst supports II. 20 g of an aqueous solution of palladium nitrate (0.15 wt%) was weighed, and 10 g of 0.5% WOx-CeO2 catalyst support II was added. After ultrasonication until homogeneous dispersion, the mixture was evaporated to dryness under slight negative pressure in a rotary evaporator. After drying and calcination, the solid catalyst was reduced at 300 °C in a hydrogen atmosphere to obtain a bifunctional catalyst 0.3% Pd-3% WOx-CeO2 for the synthesis of methyl isobutyl ketone. The XPS characterization of this bifunctional catalyst was similar to that in Example 1.

[0031] Example 6 100 g of deionized water was added to a 1 L reactor. 100 g of a 30 wt% cerium nitrate solution and 30 mL of a 25 wt% NH4OH solution were added dropwise to the reactor, maintaining the pH at 8-9. After the addition was complete, the temperature was raised to 85 °C, and the mixture was stirred and aged for 8 h to obtain a suspension of cerium hydroxide. After centrifugation and two washes with pure water, the suspension was dried at 120 °C to obtain a white powder. The cerium hydroxide solid was then heated at 800 °C under a 10% H2 / Ar atmosphere. o CeO2 support I was obtained by calcination at C for 5 h. 10 g of an aqueous solution of ammonium metatungstate (3 wt%) was prepared, and 10 g of CeO2 support I was added. The mixture was ultrasonically dispersed until homogeneous, and the suspension was shaken and impregnated in an 80 °C constant-temperature shaker until dry. The resulting solid was ground into powder and calcined in a muffle furnace at 800 °C for 180 min to obtain a series of 0.5%WOx-CeO2 catalyst supports II. 20 g of an aqueous solution of palladium nitrate (0.25 wt%) was weighed, and 10 g of 0.5%WOx-CeO2 catalyst support II was added. After ultrasonication until homogeneous dispersion, the mixture was evaporated to dryness under slight negative pressure in a rotary evaporator. After drying and calcination, the solid catalyst was reduced at 300 °C in a hydrogen atmosphere to obtain a bifunctional catalyst 0.5%Pd-3%WOx-CeO2 for the synthesis of methyl isobutyl ketone. The XPS characterization of this bifunctional catalyst was similar to that in Example 1.

[0032] Comparative Example 1 On CeO2 support I prepared in Example 5, 0.3% Pd was loaded and reduced in a hydrogen atmosphere at 300 °C to obtain a bifunctional catalyst 0.3%Pd-CeO2 for the synthesis of methyl isobutyl ketone.

[0033] Comparative Example 2 A commercially available M3 catalyst (Pd / resin) from a certain company can be used for the synthesis of methyl isobutyl ketone after reduction at 80 °C in a hydrogen atmosphere.

[0034] Catalytic performance testing: The catalysts from Examples 1-6 and Comparative Examples 1-2 were tested in a fixed-bed reactor at an acetone mass hourly space velocity (MHSV) of 4 h⁻¹. -1 The conversion rate and selectivity were evaluated under the conditions of 3 MPa pressure and 130 °C, and samples were taken at 500 h and 1000 h respectively for chromatographic analysis. The results are listed in Table 1.

[0035] Table 1. Conversion and selectivity of catalysts in Examples 1-6 and Comparative Examples 1-2

[0036] In summary, when the WOx content is 3%, the bifunctional catalyst exhibits stronger acidity and better dehydration activity; when the Pd loading is 0.3%, the selectivity of methyl isobutyl ketone reaches as high as 97%, effectively reducing raw material costs.

[0037] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A bifunctional catalyst, characterized in that, The bifunctional catalyst includes a support and an active component; The carrier includes CeO2; The CeO2 has oxygen vacancies; The active component includes Pd.

2. The bifunctional catalyst according to claim 1, characterized in that, The carrier is modified with a modification agent; The modifying agent includes transition metal oxides; Preferably, the transition metal oxide is selected from WOx; Preferably, based on the mass percentage of the bifunctional catalyst, the content of the modifying agent is 0.2-5%, and the content of the active component is 0.2-1%.

3. The bifunctional catalyst according to claim 2, characterized in that, The bifunctional catalyst was characterized by XPS. In the CeO2-O1s spectrum, the lattice oxygen Lo (529.5±0.3 eV), oxygen vacancy Vo (530.8±0.3 eV), and chemisorbed oxygen Co (533.1±0.3 eV) were observed.

4. A method for preparing a bifunctional catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Obtain CeO2 support I with oxygen vacancies; S2. Mix the aqueous solution containing the modification agent precursor with the CeO2 support I to obtain a suspension. Shake and impregnate the suspension until dry to obtain a solid. Grind the solid into powder and calcine to obtain catalyst support II. S3. Mix an aqueous solution containing palladium source with the catalyst support II in equal volume, evaporate the water, dry and calcine, and reduce in a reducing atmosphere to obtain the bifunctional catalyst.

5. The preparation method according to claim 4, characterized in that, In S1, the method for preparing the CeO2 support I with oxygen vacancies includes the following steps: An aqueous solution containing Ce(NO3)3 is mixed with alkaline solution I to obtain mixed solution I. After aging, a cerium hydroxide precursor is obtained. The precursor is then calcined under an H2 / Ar atmosphere to obtain the CeO2 support I with oxygen vacancies.

6. The preparation method according to claim 5, characterized in that, The alkaline solution I is selected from an aqueous solution of at least one of sodium hydroxide, sodium carbonate, sodium bicarbonate, and ammonia. Preferably, the pH value of the mixed solution I is 8-9; Preferably, the aging conditions include: a temperature of 90~95 ℃ and a reaction time of 12~24 h under stirring. Preferably, the calcination conditions include: an atmosphere of 10-100% H2 / Ar, a temperature of 800-1000 ℃, and a time of 4-6 h.

7. The preparation method according to claim 4, characterized in that, In S2, when the modifying agent is WOx, the corresponding modifying agent precursor is ammonium metatungstate.

8. The preparation method according to claim 4, characterized in that, In S2, the calcination conditions include: an atmosphere of air, a temperature of 800~1000 ℃, and a time of 2~4 h.

9. The preparation method according to claim 4, characterized in that, In S3, the palladium source is selected from at least one of palladium nitrate and palladium chloride.

10. The application of a bifunctional catalyst according to any one of claims 1 to 3 or a bifunctional catalyst obtained by the preparation method according to any one of claims 4 to 9 in the one-step catalytic preparation of methyl isobutyl ketone from acetone; Preferably, the one-step catalytic preparation of methyl isobutyl ketone from acetone is carried out in a fixed-bed reactor.

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