High-activity bifunctional catalytic material, preparation method and application thereof

Abstract

The application discloses a kind of high-activity bifunctional catalytic materials and preparation method and application, preparation method includes: aluminum nitrate is dissolved in water with urea, add ethanol and surfactant, carry out crystallization after first calcination, obtain first calcination powder;First calcination powder is added to ammonium metatungstate solution, after mixing evenly, rotary evaporation is obtained solid, the solid is second calcined, obtain final powder;Final powder is evenly added to water, after loading with palladium salt solution, three times calcination is carried out, and high-activity bifunctional catalytic material is obtained.The high-activity bifunctional catalytic material of palladium-atomic dispersion tungsten oxide-double active site is constructed by two-step method in the application, the problem that pure palladium catalyst cannot be deeply mineralized methyl ethyl ketone at low temperature is solved.The palladium-tungsten synergistic effect of the prepared high-activity bifunctional catalytic material makes it have excellent methyl ethyl ketone low-temperature deep oxidation activity and reaction stability.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of air pollution control, and particularly relates to a high-activity bifunctional catalytic material and a preparation method and application thereof. BACKGROUND

[0002] Volatile organic compounds (VOCs) refer to organic compounds with a boiling point lower than 260 DEG C under atmospheric pressure (250.101 kpa) or a saturated vapor pressure higher than 133.32 Pa at room temperature (25 DEG C) and discharged into the air in the form of gaseous molecules. VOCs are various, mainly including aliphatic hydrocarbons, oxygen-containing hydrocarbons, aromatic hydrocarbons and derivatives thereof, halogen-containing hydrocarbons, nitrogen-containing hydrocarbons, sulfur-containing hydrocarbons and the like, and can be divided into outdoor sources and indoor sources. Oxygen-containing volatile organic compounds (OVOCs such as formaldehyde, acetone, methyl ethyl ketone, ethyl acetate and the like) are worrying because they are extremely easy to form ozone, cause photochemical smog, urban haze and other air pollution problems, and have extremely strong toxicity and carcinogenicity to the immune system, kidney and respiratory system of human body. Among them, methyl ethyl ketone (MEK) is a typical OVOC, which is widely used as a solvent in many large processes (such as printing and manufacturing). Therefore, developing a strategy for efficiently removing methyl ethyl ketone is of great significance for controlling VOCs.

[0003] Complete catalytic oxidation is a very promising method for treating volatile organic compounds (especially at low concentrations (<0.5vol.%)) into carbon dioxide and water. Developing efficient and promising low-temperature VOCs emission reduction catalysts continues to attract widespread attention. Supported noble metal catalysts are widely used in the removal of oxygen-containing hydrocarbons due to their good activity and strong regenerability. However, the further industrial application of pure palladium-based catalysts is limited by factors such as single active site and insufficient deep oxidation capacity. SUMMARY

[0004] In order to overcome the problems of single active site and insufficient deep oxidation capacity of the palladium-based catalytic material in the prior art, the purpose of the present application is to provide a high-activity bifunctional catalytic material and a preparation method and application thereof. The catalytic material prepared by the method has good methyl ethyl ketone deep oxidation capacity and reaction stability, and has important application prospects in the field of low-temperature purification of volatile organic pollutants.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0006] A preparation method of a high-activity bifunctional catalytic material, comprising the following steps:

[0007] The aluminum nitrate nine hydrate and urea are dissolved in deionized water, ethanol and surfactant are added, then crystallization is carried out, centrifugation, washing, drying are carried out, and then primary roasting is carried out to obtain primary roasting powder;

[0008] The primary roasting powder is added to the ammonium metatungstate solution, and after stirring and reaction, the solid is obtained by rotary evaporation, and the final powder is obtained by secondary roasting of the solid;

[0009] The final powder is added to water to obtain a tungsten oxide-aluminum oxide carrier suspension, the pH is adjusted to 6-11, then a palladium salt solution is added, and the reaction is carried out at 90-110°C for 1-2h to obtain a light yellow solid;

[0010] The light yellow solid is subjected to three times of roasting to obtain a high-activity bifunctional catalytic material.

[0011] Further, the molar ratio of aluminum nitrate nine hydrate to urea is 3-6:6-12mmol.

[0012] Further, the surfactant is dodecylamine.

[0013] Further, the amount ratio of aluminum nitrate nine hydrate to ethanol is 3-6mmol:8-12mL;

[0014] The amount ratio of aluminum nitrate nine hydrate to surfactant is 3-6mmol:0.25-0.5g.

[0015] Further, the crystallization temperature is 150-170°C, and the time is 3-5h;

[0016] The temperature of the primary roasting is 550-650°C, and the time is 4-6h; the temperature is raised to 550-650°C at a temperature rise rate of 2-5°C / min.

[0017] Further, the mass ratio of the primary roasting powder to ammonium metatungstate is 0.5g:0.00275-0.11g;

[0018] The temperature of the secondary roasting is 600-650°C, and the time is 4-6h; the temperature is raised to 600-650°C at a temperature rise rate of 2-5°C / min.

[0019] Further, the amount ratio of the final powder to the palladium salt solution is 0.2g:5mL, and the concentration of the palladium salt solution is 0.00015-0.0006g / mL;

[0020] The palladium salt is palladium nitrate, palladium chloride or sodium tetrachloropalladate.

[0021] Further, the temperature of the third roasting is 200-300°C, and the time is 1-1.5h; the third roasting is carried out under a mixed gas of hydrogen and argon;

[0022] The volume percentage of hydrogen in the mixed gas of hydrogen and argon is 5-10%;

[0023] The flow rate of the mixed gas of hydrogen and argon is 100-200 mL / min.

[0024] A high-activity bifunctional catalytic material, the specific surface area of the catalytic material is 159.0-170.9 m 2 / g, and the micropore volume is 0.067-0.071 cm 3 / g.

[0025] Application of the high-activity bifunctional catalytic material in purification of volatile oxygen-containing hydrocarbons.

[0026] Further, under the conditions of 40-260 DEG C, space velocity 30000-45000 h -1 , and oxygen volume concentration 10-21%, the high-activity bifunctional catalytic material realizes purification of methyl ethyl ketone with a volume concentration of 0.6%.

[0027] Compared with the prior art, the high-activity bifunctional catalytic material has the beneficial effects that:

[0028] In the application, the complexing degree of the gamma-AlOOH precursor is improved by adding a surfactant into an aluminum nitrate and urea solution, and the pore volume and specific surface area of the two-dimensional layered alumina carrier are increased, which is beneficial to adsorption of pollutant molecules and dispersion of active metals, thereby improving the reaction performance of the catalyst. The atomic dispersion of tungsten oxide is introduced on the surface of the alumina carrier by using a one-step method. In the application, the formation of high-stability palladium clusters is further promoted by adjusting the pH to 6-11, the charge balance process between the carrier and the noble metal is accelerated by the strong interaction between the palladium cluster active phase and the atomic dispersion of tungsten oxide, and the low-temperature catalytic efficiency and reaction stability of the bifunctional catalytic material are greatly improved. In the application, the special bifunctional active site of palladium-tungsten oxide on the two-dimensional alumina carrier is successfully constructed by a simple two-step method, the problem of high cost of the supported noble metal is solved to some extent, the defects of single palladium-based catalytic material, such as single active site and insufficient deep oxidation capacity, are overcome, and the bifunctional catalytic material has the prospect of universal application.

[0029] The high-activity bifunctional catalytic material prepared in the application has a specific surface area of 159.0-170.9 m 2 / g, and a micropore volume of 0.067-0.071 cm 3 / g, and has a large specific surface area, which is beneficial to improving the catalytic efficiency.

[0030] The high-activity bifunctional catalytic material prepared in the application can be applied in purification of volatile oxygen-containing hydrocarbons. Under the conditions of 40-260 DEG C, space velocity 30000-45000 h -1Under the condition of oxygen volume concentration 10-20%, the purification of methyl ethyl ketone volume concentration 0.6% is realized; the prepared catalytic material of the application has good methyl ethyl ketone deep oxidation capacity and reaction stability, and has important application prospect in the field of volatile organic pollutants low-temperature purification. BRIEF DESCRIPTION OF DRAWINGS

[0031] Figure 1 It is the HADDF image of the high-activity bifunctional catalytic material in the application under transmission electron microscope; wherein: (a) is low magnification, (b) is medium magnification, and (c) is high magnification;

[0032] Figure 2 It is the EDS-mapping picture of the high-activity bifunctional catalytic material in the application; wherein, (a) is the low magnification of HADDF picture, (b) is the EDS of tungsten (W) element, and (c) is the EDS of palladium (Pd) element;

[0033] Figure 3 It is the XRD spectrum of the high-activity bifunctional catalytic material in the application;

[0034] Figure 4 It is the purification efficiency curve of the high-activity bifunctional catalytic material in the application to methyl ethyl ketone;

[0035] Figure 5 It is Figure 4 The corresponding CO2 generation rate curve;

[0036] Figure 6 It is the cycle stability test of the high-activity bifunctional catalytic material in the application;

[0037] Figure 7 It is the long-term stability test efficiency curve of the high-activity bifunctional catalytic material in the application to methyl ethyl ketone purification. DETAILED DESCRIPTION

[0038] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the accompanying drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized in many different forms and is not limited to the embodiments described herein. The present application will be described in detail below in conjunction with the embodiments.

[0039] The complex degree of the gamma-AlOOH precursor is improved and the pore volume and specific surface area of the two-dimensional layered alumina carrier are increased by adding a surfactant to an aluminum nitrate and urea solution in the application, which is beneficial to the adsorption of pollutant molecules and the dispersion of active metals, thereby improving the reaction performance of the catalyst. And atomic dispersion of tungsten oxide is introduced on the surface of the alumina carrier through a simple impregnation-rotary evaporation drying method. In the application, the formation of high-stable palladium clusters is further promoted by adjusting the pH of the tungsten oxide-alumina carrier suspension, and the charge balance process between the carrier and the noble metal is accelerated through the strong interaction between the palladium cluster active phase and the atomic dispersion of tungsten oxide, which greatly improves the low-temperature catalytic efficiency and reaction stability of the bifunctional catalytic material. In the application, the special bifunctional active site of palladium-tungsten oxide on the two-dimensional alumina carrier is successfully constructed through a two-step ligand pyrolysis method, which solves the problem of high cost of supported noble metals to some extent, overcomes the defects of single palladium-based catalytic material such as single active site and insufficient deep oxidation capacity, and has the prospect of universal application.

[0040] The preparation method of the high-activity bifunctional catalytic material in the application is as follows:

[0041] Aluminum nitrate nonahydrate and urea are dissolved in deionized water, and stirred uniformly. Then ethanol is slowly added dropwise, and a surfactant is added, and further stirred vigorously. The mixed solution is crystallized in a reaction kettle, centrifuged and washed for multiple times, and dried to obtain a white precipitate, and once calcined to obtain a solid powder. Ammonium metatungstate is dissolved in deionized water and stirred uniformly, and the solid powder is added, and after the reaction is completed, rotary evaporation is performed, and the obtained powder is twice calcined to obtain the final powder.

[0042] The final powder obtained above is dispersed in water, stirred uniformly, and the pH is adjusted to 6-11. After stirring uniformly, it is heated to a certain temperature, and continuously stirred, and a palladium nitrate dihydrate aqueous solution is added dropwise to form a light yellow transparent solution. After the reaction is completed, centrifugation, washing and vacuum drying are performed, and the yellow-brown powder is calcined in a hydrogen-argon atmosphere to obtain the high-activity bifunctional catalytic material.

[0043] Specifically, the preparation method of the high-activity bifunctional catalytic material in the application includes the following steps:

[0044] (1) 3-6 mmoL of aluminum nitrate nonahydrate and 6-12 mmoL of urea are dissolved in 65-75 mL of deionized water, and stirred at a speed of 400-600 rpm for 10-30 min to make them uniformly dispersed, to obtain a transparent solution;

[0045] (2) To the transparent solution obtained in step (1), 8-12 mL of ethanol was added dropwise, followed by 0.25-0.5 g of a surfactant (dodecylamine), and stirring was performed at a speed of 400-600 rpm for 30-60 min to obtain a transparent mixed solution;

[0046] (3) The transparent mixed solution obtained in step (2) was placed in a hydrothermal reactor for crystallization to generate γ-AlOOH, the crystallization temperature was 150-170 °C, and the time was 3-5 h, to obtain a milky white suspension;

[0047] (4) The milky white suspension obtained in step (3) was centrifuged at a speed of 6000-10000 rpm, washed with a mixed solution of ethanol and deionized water in a volume ratio of 1:1-1.5, and dried at 80-120 °C to obtain a white solid powder;

[0048] (5) The white solid powder obtained in step (4) was subjected to a first calcination in an air atmosphere, so that the γ-AlOOH was converted into aluminum oxide, the temperature was 550-650 °C, the time was 4-6 h, and the temperature rising rate was 2-5 °C / min, to obtain a powder.

[0049] (6) 0.00275-0.11 g of ammonium metatungstate was dissolved in 50 mL of water to be uniformly dispersed, 0.5 g of the powder obtained by the first calcination in step (5) was added, stirring was performed at a speed of 400-800 rpm for 2-6 h, the temperature for rotary evaporation was 50-70 °C, and the speed was 120-140 r / min.

[0050] (7) The powder obtained by rotary evaporation in step (6) was subjected to a second calcination in an air atmosphere to generate tungsten oxide, the temperature was 600-650 °C, the time was 4-6 h, and the temperature rising rate was 2-5 °C / min, to obtain a final powder.

[0051] (7) 0.2 g of the final powder obtained by the second calcination in step (6) was placed in 45-50 mL of deionized water to be uniformly dispersed, a 0.25 mol / L anhydrous sodium carbonate solution was used to adjust the pH to 6-11, and stirring was continued to make it uniform.

[0052] (8) The solution in step (7) was heated to 90-110 °C, 5 mL of a 0.00015-0.0008 g / mL aqueous solution of palladium nitrate (palladium chloride or sodium tetrachloropalladate) was added dropwise, and stirring was continued at a speed of 600-800 rpm for 1-2 h.

[0053] (9) After the solution obtained in step (8) was allowed to cool to room temperature, centrifugation was performed at a speed of 6000-9000 rpm, and washing was performed with deionized water for 5 times, and vacuum drying was performed at 50-70 °C to obtain a light yellow solid powder;

[0054] (10) the light yellow solid powder obtained in step (9) is calcined under a mixed gas atmosphere of hydrogen and argon, the flow rate of the mixed gas of hydrogen and argon is 100-200 mL / min, the temperature is 200-300℃, and the time is 1-1.5h, to obtain the high-activity bifunctional catalytic material. The volume percentage of hydrogen in the mixed gas of hydrogen and argon is 5-10%.

[0055] The high-activity bifunctional catalytic material prepared by the method has two active sites of palladium clusters and atomically dispersed tungsten oxide, has a relatively high specific surface area (159.0-170.9 m 2 / g) and micropore volume (0.067-0.071 cm 3 / g).

[0056] The high-activity bifunctional catalytic material prepared by the method can be applied in the purification of volatile oxygen-containing hydrocarbons. Specifically, under the conditions of 40-260℃, space velocity of 30000-45000h -1 , and oxygen volume concentration of 10-20%, the volume concentration of methyl ethyl ketone is 0.6%. The catalytic material prepared by the method has good low-temperature deep oxidation capacity and chlorine resistance.

[0057] The following is a specific example.

[0058] Example 1: Alumina (Al2O3) is prepared by a hydrothermal method

[0059] (1) 3mmol of aluminum nitrate nonahydrate and 6mmol of urea are dissolved in 70mL of deionized water, and stirred at a speed of 600rpm for 10min to make them uniformly dispersed;

[0060] (2) 10mL of ethanol is added dropwise to the transparent solution obtained in step (1), followed by the addition of a surfactant, dodecylamine, and stirring at a speed of 500rpm for 30min to make them uniformly dispersed;

[0061] (3) the transparent solution obtained in step (2) is placed in a hydrothermal reactor for crystallization, the crystallization temperature is 160℃, and the time is 3h;

[0062] (4) the milky white suspension obtained in step (3) is centrifuged at a speed of 6000-10000rpm, washed with a mixed solution of ethanol and deionized water at a ratio of 1:1, and dried at 80℃ to obtain a white solid powder;

[0063] (5) the white powder obtained in step (4) is calcined in air atmosphere at a temperature of 600℃ for 4h, and the heating rate is 2℃ / min, to obtain a white powder, which is alumina (Al2O3).

[0064] Example 2: Preparation of the alumina support (WO3 / Al2O3) by one-step synthesis

[0065] (1) 0.088 g of ammonium metatungstate was dissolved in 50 mL of water to make it uniformly dispersed, 0.5 g of the alumina powder obtained in Example 1 was added, and stirred at a speed of 600 rpm for 2 h, and the temperature of the rotary evaporation was 60 °C and the speed was 130 r / min.

[0066] (2) The powder obtained by the rotary evaporation in step (1) was subjected to secondary calcination in an air atmosphere at a temperature of 600 °C for 4 h, and the temperature increasing rate was 2 °C / min. Finally, a white powder was obtained, which was the tungsten oxide-alumina support (WO3 / Al2O3).

[0067] Example 3: Construction of the palladium-tungsten oxide dual active site by oil bath method

[0068] (1) 0.2 g of the WO3 / Al2O3 solid powder prepared in Example 2 was dissolved in 45 mL of deionized water, and stirred at a speed of 600 rpm for 30 min to make it uniformly dispersed; a 0.25 mol / L anhydrous sodium carbonate solution was used to adjust the pH to 10, and the stirring was continued to make it uniform, and a mixed solution was obtained.

[0069] (2) After the mixed solution obtained in step (1) was heated to 100 °C, 5 mL of a 0.0004 g / mL aqueous solution of palladium nitrate was added dropwise, and the stirring was continued at a speed of 600 rpm for 1 h to obtain a solution.

[0070] (3) After the solution obtained in step (2) was allowed to cool to room temperature, it was centrifuged at a speed of 8000 rpm, and washed with deionized water for 6 times, and dried under vacuum at 60 °C to obtain a light yellow solid powder;

[0071] (4) The light yellow solid powder obtained in step (3) was calcined in a hydrogen-argon atmosphere (the volume percentage of hydrogen in the hydrogen-argon atmosphere was 10%), the flow rate was 150 mL / min, the temperature was 200 °C, and the time was 1 h, and finally a high-activity bifunctional catalyst Pd / WO3 / Al2O3 was obtained.

[0072] Referring to Figs. (a), (b) and (c) in Figure 1 The high-activity bifunctional catalytic material prepared in Example 3 of the present application has a clear two-dimensional layered structure.

[0073] Referring to Figs. (a), (b) and (c) in Figure 2 From the results analysis, it can be seen that the tungsten oxide of the high-activity bifunctional catalytic material prepared in Example 3 of the present application is obviously atomically dispersed, and the palladium clusters are uniformly distributed. Figure 2 Referring to Figs. (a), (b) and (c) in

[0074] Figure 3 ​The high-activity bifunctional catalytic material prepared in Embodiment 3 of the present application has good crystallinity and clear crystal phase.

[0075] Embodiment 4

[0076] (1) 3 mmol (1.13 g) of aluminum nitrate nonahydrate and 6 mmol (0.36 g) of urea were dissolved in 70 mL of deionized water, and stirred at a rotation speed of 500 rpm for 20 min to uniformly disperse;

[0077] (2) 10 mL of ethanol was added dropwise to the clear solution obtained in step (1), and then 0.25 g of dodecylamine was added, and stirred at a rotation speed of 500 r / min for 60 min to uniformly disperse;

[0078] (3) The transparent solution obtained in step (2) was carefully placed in a hydrothermal reactor, and reacted at a temperature of 160℃ for 3 h;

[0079] (4) The milky white suspension obtained in step (3) was centrifuged, washed with a mixture of ethanol and deionized water (volume ratio 1:1) for 5 times, and dried at 90℃ to obtain a white solid powder;

[0080] (5) The white powder obtained in step (4) was subjected to preliminary calcination in a muffle furnace at a temperature of 550℃ for 4 h, and the temperature was raised at a rate of 2℃ / min to obtain a powder;

[0081] (6) 0.088 g of ammonium metatungstate was dissolved in 50 mL of water and stirred to uniformly disperse, and then 0.5 g of the powder obtained in step (5) subjected to preliminary calcination in step (5) was added, and stirred at a rotation speed of 600 rpm for 4 h. After the reaction, a rotary evaporator was used, the water bath temperature was set to 60℃, and the rotation speed was 130 r / min;

[0082] (7) The powder obtained by rotary evaporation in step (6) was calcined again in a muffle furnace at a temperature of 600℃ for 4 h, and the temperature was raised at a rate of 2℃ / min;

[0083] (8) 0.2 g of the powder obtained by the second calcination in step (7) was accurately weighed, dissolved in 45 mL of water, and stirred for 30 min to uniformly disperse. Then, the pH was adjusted to 9.5 with a 0.25 mol / L anhydrous sodium carbonate solution, and continuously stirred until uniformly mixed;

[0084] (9) The solution in step (8) was heated to 100℃, and 5 mL of a 0.0006 g / mL aqueous solution of palladium nitrate was added dropwise, and continuously stirred at a rotation speed of 800 rpm for 1.5 h;

[0085] (10) After the reaction in step (9) is completed, the mixed solution is cooled to room temperature, centrifuged at a rotation speed of 9000 r / min, washed with deionized water 6 times, and then dried in a vacuum at 60°C to obtain a light yellow solid powder;

[0086] (11) The powder obtained in step (10) is calcined at a flow rate of 200 mL / min in a H2 / Ar atmosphere (10% hydrogen in argon) at a temperature of 200°C for 2h to finally prepare a high-activity bifunctional catalyst Pd / WO3 / Al2O3 of palladium-atomically dispersed tungsten oxide.

[0087] Example 5

[0088] The WO3 / Al2O3 support obtained in Example 2 is accurately weighed at 0.2 g in 45 ml of DI water, and stirred at 700 r / min for 45 min to uniformly disperse.

[0089] The pH value of the mixed solution is adjusted to 10.5 with a 0.25 mol / L anhydrous sodium carbonate solution, and stirring is continued until the mixture is uniform. After the mixture is heated to 100°C, 5 mL of a 0.0006 g / mL aqueous palladium nitrate solution is added dropwise, and stirring is continued at a rotation speed of 800 r / min for 1 hour. After the reaction is completed, the solution is cooled to room temperature, centrifuged at a rotation speed of 10000 r / min, washed with deionized water 7 times, and then dried in a vacuum at 60°C. The light yellow solid powder obtained is calcined at a flow rate of 100 mL / min in a H2 / Ar atmosphere (10% hydrogen in argon) at a temperature of 200°C for 1 hour to prepare a high-activity bifunctional catalyst Pd / WO3 / Al2O3 of palladium-atomically dispersed tungsten oxide.

[0090] Example 6

[0091] (1) 6 mmoL (2.26 g) of aluminum nitrate nonahydrate and 12 mmoL (0.72 g) of urea are dissolved in 71 ml of DI water, and stirred at a speed of 500 rpm for 30 min to uniformly disperse;

[0092] (2) To the clear solution obtained in step (1), 11 mL of ethanol is added dropwise, followed by the addition of 0.50 g of dodecylamine, and stirring is continued at a rotation speed of 500 r / min for 40 min to uniformly disperse;

[0093] (3) The clear solution obtained in step (2) is poured into a 100 mL hydrothermal reactor, and hydrothermally reacted at 160°C for 5h;

[0094] (4) After the hydrothermal reaction is completed and the temperature is decreased to room temperature, the mixed solution obtained in step (3) is centrifuged and washed with a mixture of ethanol and deionized water (1:1.2) for 5 times, and then dried at 100°C to obtain a white powder;

[0095] (5) The white powder obtained in step (4) is first calcined in a muffle furnace, the temperature is set to 550°C, the calcination time is 6h, and the heating rate is 5°C / min;

[0096] (6) 0.066g of ammonium metatungstate is dissolved in 50mL of deionized water, stirred thoroughly, and then stirred at 800rpm for 2 hours. After the reaction is completed, rotary evaporation is performed at a water temperature of 60°C and a rotation speed of 125r / min;

[0097] (7) The powder obtained in step (6) is calcined in a muffle furnace at a temperature of 600°C for 5h, and the heating rate is 2°C / min, to obtain a WO3 / Al2O3 carrier.

[0098] (8) 0.2g of the WO3 / Al2O3 carrier obtained in step (7) is accurately weighed, dissolved in 45mL of deionized water, and stirred for 40min to uniformly disperse. Then, the pH of the mixed solution is adjusted to 10 with a 0.25mol / L anhydrous sodium carbonate solution, and stirring is continued until it is completely uniform;

[0099] (9) The solution in step (8) is heated to 100°C, and stirring is continued at a rotation speed of 800rpm, 5mL of 0.0008g / mL aqueous palladium nitrate solution is added dropwise, and stirring is continued for 1h;

[0100] (10) After the reaction in step (9) is completed, the mixed solution is cooled to room temperature, and then centrifuged at a rotation speed of 8500r / min, washed with deionized water for 6 times, and then dried in a vacuum drying oven at 60°C to obtain a light yellow solid powder;

[0101] (11) The prepared light yellow solid powder is calcined at a temperature of 200°C for 1h under the condition of 200mL / min and H2 / Ar atmosphere (the volume percentage of hydrogen in the hydrogen and argon atmosphere is 5%), and a high-activity bifunctional catalyst is finally obtained, which is denoted as Pd / WO3 / Al2O3.

[0102] Example 7

[0103] (1) 4mmoL of aluminum nitrate nonahydrate and 8mmoL of urea are dissolved in 65ml of DI water, and stirred at a speed of 450r / min for 30min to uniformly disperse;

[0104] (2) To the clear solution obtained in step (1), 8 mL of ethanol was added dropwise, followed by the addition of 0.35 g of dodecylamine, and stirring was performed at a rotation speed of 500 r / min for 40 min to uniformly disperse the same;

[0105] (3) The clear solution obtained in step (2) was poured into a 100 mL hydrothermal reactor, and hydrothermal reaction was performed at 155 °C for 4 h;

[0106] (4) After the hydrothermal reaction was completed and the temperature was lowered to room temperature, the mixture obtained in step (3) was centrifuged at a rotation speed of 6000 rpm, and washed with a mixture of ethanol and deionized water (1:1.4) for 5 times, and then dried at 80 °C to obtain a white powder;

[0107] (5) The white powder obtained in step (4) was first calcined in a muffle furnace, the temperature was set to 600 °C, the calcination time was 5 h, and the temperature rising rate was 2 °C / min;

[0108] (6) 0.033 g of ammonium metatungstate was dissolved in 50 mL of deionized water, and stirred sufficiently, and then stirred at 400 rpm for 6 hours. After the reaction was completed, rotary evaporation was performed, the water temperature was 60 °C, and the rotation speed was 130 r / min;

[0109] (7) The powder obtained in step (6) was calcined in a muffle furnace at a temperature of 600 °C for 4 h, and the temperature rising rate was 2 °C / min, to obtain a WO3 / Al2O3 carrier.

[0110] (8) 0.2 g of the WO3 / Al2O3 carrier obtained in step (7) was accurately weighed, dissolved in 47 mL of deionized water, and stirred for 40 min to uniformly disperse the same. Then, the pH of the mixed solution was adjusted to 6 with a 0.25 mol / L anhydrous sodium carbonate solution, and the stirring was continued until the mixture was completely uniform;

[0111] (9) The solution in step (8) was heated to 100 °C, and stirring was continuously performed at a rotation speed of 600 rpm, and 5 mL of a 0.0005 g / mL aqueous solution of palladium chloride was added dropwise, and the stirring was continued for 2 h;

[0112] (10) After the reaction in step (9) was completed, the mixed solution was cooled to room temperature, and then centrifuged at a rotation speed of 7000 r / min, and washed with deionized water for 6 times, and then dried in a vacuum drying oven at 50 °C to obtain a light yellow solid powder;

[0113] (11) The light yellow solid powder obtained was calcined at a temperature of 300 °C for 1 h under an H2 / Ar atmosphere (the volume percentage of hydrogen in the hydrogen and argon atmosphere was 5%) at a flow rate of 170 mL / min, to finally obtain a high-activity bifunctional catalyst, which was denoted as Pd / WO3 / Al2O3.

[0114] Example 8

[0115] (1) 6 mmoL of aluminum nitrate nonahydrate and 12 mmoL of urea were dissolved in 68 ml of DI water, and stirred at 600 rpm for 30 min to make them uniformly dispersed;

[0116] (2) 12 mL of ethanol was added dropwise to the clear solution obtained in step (1), followed by 0.5 g of dodecylamine, and stirred at 400 rpm for 60 min to make them uniformly dispersed;

[0117] (3) The clear solution obtained in step (2) was poured into a 100 mL hydrothermal reactor, and hydrothermally reacted at 170℃ for 3 h;

[0118] (4) After the hydrothermal reaction was completed and cooled to room temperature, the mixture obtained in step (3) was centrifuged at 10000 rpm, and washed with a mixture of ethanol and deionized water (1:1) 5 times, and dried at 120℃ to obtain a white powder;

[0119] (5) The white powder obtained in step (4) was first calcined in a muffle furnace, set at a temperature of 650℃, and calcined for 4 h at a heating rate of 3℃ / min;

[0120] (6) 0.11 g of ammonium metatungstate was dissolved in 50 mL of deionized water, and stirred at 800 rpm for 2 h. After the reaction was completed, rotary evaporation was performed at a water temperature of 70℃ and a rotation speed of 140 r / min;

[0121] (7) The powder obtained in step (6) was calcined in a muffle furnace at a temperature of 600℃ for 6 h at a heating rate of 5℃ / min to obtain a WO3 / Al2O3 support.

[0122] (8) 0.2 g of the WO3 / Al2O3 support obtained in step (7) was accurately weighed, dissolved in 50 mL of deionized water, and stirred for 40 min to make it uniformly dispersed. Then, the pH of the mixed solution was adjusted to 11 with a 0.25 mol / L anhydrous sodium carbonate solution, and continuously stirred until completely uniform;

[0123] (9) The solution in step (8) was heated to 110℃, and 5 mL of a 0.00015 g / mL aqueous solution of sodium tetrachloropalladate was added dropwise while stirring at 700 rpm, and the stirring was continued for 1 h;

[0124] (10) After the reaction in step (9) was completed, the mixed solution was cooled to room temperature and centrifuged at 9000 r / min, washed with deionized water 6 times, and dried in a vacuum drying oven at 70℃ to obtain a light yellow solid powder;

[0125] (11) The light yellow solid powder prepared was calcined at 250°C for 1.5h under an H2 / Ar atmosphere (10% hydrogen in argon) at a rate of 150mL / min to obtain a high-activity bifunctional catalyst, denoted as Pd / WO3 / Al2O3.

[0126] Example 9

[0127] (1) 3mmol of aluminum nitrate nonahydrate and 6mmol of urea were dissolved in 75ml of DI water, and stirred at a speed of 400rpm for 30min to uniformly disperse;

[0128] (2) 10ml of ethanol was added dropwise to the clear solution obtained in step (1), followed by the addition of 0.25g of dodecylamine, and stirred at a speed of 600rpm for 30min to uniformly disperse;

[0129] (3) The clear solution obtained in step (2) was poured into a 100ml hydrothermal reactor, and hydrothermally reacted at 150°C for 5h;

[0130] (4) After the hydrothermal reaction was completed and the temperature was lowered to room temperature, the mixture obtained in step (3) was centrifuged at a speed of 8000rpm, and washed with a mixture of ethanol and deionized water (1:1.5) for 5 times, and dried at 110°C to obtain a white powder;

[0131] (5) The white powder obtained in step (4) was first calcined in a muffle furnace at a temperature of 550°C for 6h, and the temperature was raised at a rate of 5°C / min;

[0132] (6) 0.00275g of ammonium metatungstate was dissolved in 50ml of deionized water, and stirred thoroughly, and then stirred at a speed of 600rpm for 4h. After the reaction was completed, rotary evaporation was performed at a water temperature of 50°C and a rotation speed of 120rpm;

[0133] (7) The powder obtained in step (6) was calcined in a muffle furnace at a temperature of 620°C for 5h, and the temperature was raised at a rate of 4°C / min to obtain a WO3 / Al2O3 support.

[0134] (8) 0.2g of the WO3 / Al2O3 support obtained in step (7) was accurately weighed, dissolved in 45ml of deionized water, and stirred for 40min to uniformly disperse. Then, the pH of the mixed solution was adjusted to 8 using a 0.25mol / L anhydrous sodium carbonate solution, and the stirring was continued until it was completely uniform;

[0135] (9) The solution in step (8) was heated to 90°C, and stirred at a speed of 650rpm, and 5ml of a 0.0008g / mL aqueous palladium nitrate solution was added dropwise, and the stirring was continued for 1.5h;

[0136] (10) After the reaction of step (9) is completed, the mixed solution is cooled to room temperature, then centrifuged at a rotation speed of 6000 r / min, washed with deionized water for 6 times, and dried in a vacuum drying oven at 60°C to obtain a light yellow solid powder;

[0137] (11) The light yellow solid powder prepared is calcined at a temperature of 270°C for 1 h under a hydrogen argon atmosphere (the volume percentage of hydrogen in the hydrogen argon atmosphere is 7%) at a flow rate of 120 mL / min, to obtain a high-activity bifunctional catalyst, denoted as Pd / WO3 / Al2O3.

[0138] Comparative Example 1

[0139] (1) 0.2 g of the Al2O3 solid powder prepared in Example 1 is accurately weighed out and placed in 45 ml of DI (deionized) water, and stirred at 600 rpm for 40 min to uniformly disperse; the pH value is adjusted to 10 with a 0.25 mol / L anhydrous sodium carbonate solution, and then continuously stirred until the mixture is uniform.

[0140] (2) After the mixed solution obtained in step (1) is heated to 100°C, 5 mL of a 0.0004 g / mL aqueous palladium nitrate solution is added dropwise, and the stirring is continued at a rotation speed of 620 r / min for 1 h.

[0141] (3) After the solution obtained in step (2) is cooled to room temperature, centrifugation is performed at a rotation speed of 8000 r / min, washed with deionized water for 5 times, and then dried in a vacuum drying oven at 60°C to obtain a light yellow solid powder;

[0142] (4) The powder prepared in step (3) is reduced and calcined at a flow rate of 150 mL / min, a temperature of 200°C, a heating rate of 2°C / min, and under a hydrogen argon atmosphere (the volume percentage of hydrogen in the hydrogen argon atmosphere is 10%) for 1 h to obtain a pure palladium catalyst material Pd / Al2O3.

[0143] Comparative Example 2

[0144] 0.2 g of the alumina support obtained in Example 1 was dispersed in 45 mL of deionized water and stirred at 800 rpm for 40 min to ensure uniform dispersion. The pH was adjusted to 10.5 using 0.25 mol / L anhydrous sodium carbonate solution, and stirring was continued to ensure homogeneity. The mixed solution was heated to 100 °C, and 5 mL of a 0.0006 g / mL palladium nitrate aqueous solution was added dropwise, while stirring was continued at 800 rpm for 1.5 h. After the reaction was completed, the solution was cooled to room temperature, centrifuged at 10,000 rpm, washed with deionized water, and vacuum dried at 60 °C to obtain a pale yellow solid powder. The obtained powder was calcined under a hydrogen-argon atmosphere (hydrogen volume percentage of 10%) at a flow rate of 100 mL / min, a temperature of 200 °C, and a time of 2 h to finally obtain pure palladium catalyst Pd / Al₂O₃.

[0145] Example 10: Activity test of highly active bifunctional catalytic material for the degradation of methyl ethyl ketone:

[0146] The catalytic reaction was carried out in a fixed bed. The catalyst obtained in Example 3 was tableted and sieved (40-60 mesh). 0.2 g of the sieved catalyst was accurately weighed, and methyl ethyl ketone was used as a probe gas. The concentration of the reactants was controlled at 600 ppm, and the reaction space velocity was 45,000 h⁻¹. -1 With an oxygen volume concentration of 21%, the catalytic activity of the catalyst was tested at 40-260℃ (20℃ intervals), and the reaction products were monitored and analyzed by gas chromatography-mass spectrometry.

[0147] See Figures 4-5 ,from Figures 4-5 Analysis shows that when the highly active bifunctional catalytic material Pd / WO3 / Al2O3 prepared in Example 3 and the Pd / Al2O3 catalytic material prepared in Comparative Example 1 are applied to the catalytic oxidation of methyl ethyl ketone, the Pd / Al2O3 catalytic material exhibits a decreasing trend in the temperature range of 100-140℃, failing to achieve deep mineralization. However, the highly active bifunctional catalytic material Pd / WO3 / Al2O3 demonstrates excellent low-temperature degradation efficiency for methyl ethyl ketone at 40-260℃ and a space velocity of 45000 h⁻¹. -1 Under the condition of 21% oxygen volume concentration, continuous deep oxidation of methyl ethyl ketone can be achieved. 90% of methyl ethyl ketone can be deeply purified at 140℃, and the CO2 generation rate can reach 90% at 168℃.

[0148] Example 11 Cyclic stability test of highly active bifunctional catalytic materials:

[0149] The catalyst obtained in Example 3 was pressed into tablets and sieved (40-60 mesh). 0.2 g of the sieved catalyst material was accurately weighed and placed in the fixed bed of the evaluation device. Activation was performed at 200°C for 1 h, using methyl ethyl ketone as the probe gas. The concentration of the reactants was controlled at 600 ppm, and the reaction space velocity was 45000 h⁻¹. -1 The oxygen concentration was 21%. The reaction activity was recorded after stabilization at each temperature range of 40-200℃. After completing one catalytic reaction cycle, the temperature was cooled to room temperature and then reheated. This process was repeated five times to continuously test the catalytic activity of the catalyst under mixed component atmosphere conditions.

[0150] See Figure 6 ,from Figure 6 The results analysis shows that the highly active bifunctional catalytic material prepared in Example 3 of this invention exhibits better cycling performance in the low-temperature purification of methyl ethyl ketone compared to the Pd / Al2O3 catalytic material prepared in Comparative Example 1. In the five-cycle test of heating-cooling-reheating, the Tg of the highly active bifunctional catalytic material was significantly higher than that of the Pd / Al2O3 catalytic material prepared in Comparative Example 1. 90 It remains stable throughout and exhibits excellent reaction stability.

[0151] Example 12: Long-term stability test of highly active bifunctional catalytic materials:

[0152] The catalyst obtained in Example 3 was pressed into tablets and sieved (40-60 mesh). 0.2 g of the sieved catalyst material was accurately weighed and placed in the fixed bed of the evaluation device. It was activated at 200°C for 1 h, then cooled to 140°C and held. Methyl ethyl ketone was used as the probe gas, the concentration of the reactants was controlled at 600 ppm, and the reaction space velocity was 45000 h⁻¹. -1 The oxygen concentration was 21%. The catalytic activity of the catalyst under mixed component atmosphere conditions was continuously tested.

[0153] See Figure 7 As can be seen, the highly active bifunctional catalytic material prepared in Example 3 of the present invention maintained extremely excellent activity at 140°C for a test period of up to 700 hours without any decline, demonstrating extremely strong reaction stability.

[0154] This invention is not limited to the above embodiments, and variations in its specific structure are permitted. All modifications made within the scope of the independent claims of this invention are also within the scope of protection of this invention.

[0155] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

Claims

1. A method for preparing a high-activity bifunctional catalytic material, characterized in that, The method comprises the following steps: dissolving aluminum nitrate nonahydrate and urea in deionized water, adding ethanol and a surfactant, then performing crystallization, centrifuging, washing, drying, and performing primary calcination to obtain primary calcination powder; adding the primary calcination powder to an ammonium metatungstate solution, stirring until the reaction is complete, then performing rotary evaporation to obtain a solid, performing secondary calcination on the solid to obtain final powder; adding the final powder to water to obtain a tungsten oxide-aluminum oxide carrier suspension, adjusting the pH to 6-11, then adding a palladium salt solution, and reacting at 90-110℃ for 1-2h to obtain a light yellow solid; performing tertiary calcination on the light yellow solid to obtain high-activity bifunctional catalytic material; the surfactant is dodecylamine; the amount ratio of aluminum nitrate nonahydrate to ethanol is 3-6mmol:8-12mL; the amount ratio of aluminum nitrate nonahydrate to surfactant is 3-6mmol:0.25-0.5g; the crystallization temperature is 150-170℃, and the time is 3-5h.

2. The method of claim 1, wherein the high activity bifunctional catalytic material is prepared by the steps of: the amount ratio of aluminum nitrate nonahydrate to urea is 3-6:6-12mmol.

3. The method of claim 1, wherein the high activity bifunctional catalytic material is prepared by the steps of: the primary calcination temperature is 550-650℃, and the time is 4-6h; the temperature is raised to 550-650℃ at a temperature raising rate of 2-5℃ / min.

4. The method of claim 1, wherein the high activity bifunctional catalytic material is prepared by the steps of: the mass ratio of primary calcination powder to ammonium metatungstate is 0.5g:0.00275-0.11g; the secondary calcination temperature is 600-650℃, and the time is 4-6h; the temperature is raised to 600-650℃ at a temperature raising rate of 2-5℃ / min.

5. The method for preparing the highly active bifunctional catalytic material according to claim 1, characterized in that, the amount ratio of final powder to palladium salt solution is 0.2g:5mL, and the concentration of the palladium salt solution is 0.00015-0.0006g / mL; the palladium salt is palladium nitrate, palladium chloride, or sodium tetrachloropalladate.

6. The method of claim 1, wherein the high activity bifunctional catalytic material is prepared by the steps of: the tertiary calcination temperature is 200-300℃, and the time is 1-1.5h; the tertiary calcination is performed in a hydrogen and argon mixed gas; the volume percentage of hydrogen in the hydrogen and argon mixed gas is 5-10%; the flow rate of the hydrogen and argon mixed gas is 100-200mL / min.

7. A high activity bifunctional catalytic material prepared according to the method of any one of claims 1-6, characterized in that, The specific surface area of the catalytic material is 159.0-170.9 m 2 / g, the micropore volume is 0.067-0.071 cm 3 / g.

8. The use of high-activity bifunctional catalytic material prepared by the method of any one of claims 1-6 in the purification of volatile oxygen-containing hydrocarbons.

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