A preparation method of an acousto-optic catalyst for catalyzing ether bond rupture in lignin

Abstract

The application discloses a preparation method of an acousto-optic catalyst for catalyzing the cleavage of ether bonds in lignin, and belongs to the technical field of photocatalytic materials. 2+ The intercalation method is used for in-situ synthesis of ZnO in the layer spacing of MoS2, MoS2 / ZnO heterojunction catalyst is constructed, and the catalyst has strong piezoelectric response capability. The problems of traditional photocatalysts, such as fast recombination of photo-generated carriers and low mechanical energy utilization rate, are solved, and the shortcoming of the reduction of catalytic energy level after the construction of the heterojunction is also solved. Under the acousto-optic combined action, a large number of beta-O-4 bonds are broken, and high product selectivity is simultaneously achieved. The method is simple in operation and has significant technical advantages.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalytic materials, and particularly relates to a preparation method of an acousto-optic catalyst for catalyzing the cleavage of ether bonds in lignin. BACKGROUND

[0002] Lignin is the only renewable organic carbon source containing aromatic compounds in nature, and contains a large number of aromatic structures in its structure, which has great application potential in the production of fuels, chemicals, cosmetics, bioplastics and renewable aromatic hydrocarbons. Environmentally friendly and effective depolymerization of lignin is an important part of its high-value utilization, and the β-O-4 bond in lignin is the most abundant linking bond, and the depolymerization method for the β-O-4 bond is of great significance.

[0003] Among the many catalytic depolymerization methods of lignin, photocatalytic depolymerization using solar energy is attracting attention because of its low energy consumption and environmental friendliness. In the photocatalytic process, the catalyst is first excited by light to generate photo-generated electrons and photo-generated holes in the conduction band and the valence band, and then the photo-generated carriers act on lignin, resulting in depolymerization of lignin, but the recombination of photo-generated carriers is still the main factor limiting the photocatalytic efficiency. Chinese patent CN 116689008 A discloses a photocatalyst constructed by transition metal doped g-C3N4 heterojunction, which can reduce the recombination of photo-generated carriers. However, the construction of heterojunction will cause the decrease of catalytic energy level, which is not conducive to the cleavage of high bond energy chemical bonds. Chinese patent CN 116803509 A discloses a KNbO3 / MoS2 piezoelectric photocatalyst, which promotes the separation and migration of carriers through the modification of heterojunction by piezoelectric field. Moreover, the piezoelectric field can alleviate the negative effects caused by the decrease of catalytic energy level while promoting the movement of carriers. However, there are few preparation strategies for piezoelectric photocatalysts for cleaving β-O-4 bonds in lignin.

[0004] Therefore, it is necessary to study a piezoelectric photocatalyst for cleaving β-O-4 bonds in lignin. SUMMARY

[0005] To solve the above problems, the application provides a preparation method of an acousto-optic catalyst for catalyzing the cleavage of ether bonds in lignin, which is carried out according to the following steps:

[0006] A preparation method of a MoS2 / ZnO catalyst for catalyzing the cleavage of β-O-4 bonds in lignin, which is carried out according to the following steps:

[0007] (1) Raw material solution preparation: MoS2 is dissolved in a certain volume of water: ethanol (3:7) and stirred at 600 rpm for 24 h. ZnAc is dissolved in a certain volume of Mili-Q ultrapure water and stirred at 600 rpm for 24 h. The ratio of MoS2 to water: ethanol mixture is 1:100 (g / mL), and the ratio of ZnAc to Mili-Q ultrapure water is 0.4508-2.2542:100 (g / mL).

[0008] (2) Zn 2+ Ion intercalation: ZnAc solution is added to the MoS2 suspension at a certain flow rate, and stirring is continued for 24 h.

[0009] (3) Catalyst synthesis: NaOH and cetyltrimethylammonium bromide are added to the suspension in (2), and ultrasonic treatment is carried out at 90°C water bath for 2 h to generate ZnO in situ in the interlayer space of MoS2. The ultrasonic conditions are power: 150 W, frequency: 40 KHz. The solid is collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water 3 times, and dried at 60°C to obtain the catalyst. The mass ratio of NaOH to MoS2 added in step (2) is 8:5, and the mass ratio of cetyltrimethylammonium bromide to MoS2 added in step (2) is 1:2.

[0010] (4) Catalyst annealing: The solid catalyst is annealed at a certain temperature in a tube furnace under N2 atmosphere for 3 h.

[0011] (5) Catalyst performance test: The substrate 0.05 mmol / L is dissolved in acetonitrile: water (3:2) 50 mL, and the catalyst dosage is 1 mg / mL. The ultrasonic conditions are 150 W 40 KHz, the light source distance from the quartz reactor is 20 cm, and the intensity is 1000 W / m 2 . During the reaction, a peristaltic pump and a thermostat are used to control the temperature at 25°C.

[0012] (6) Preferably, the flow rate of the ZnAc solution in (2) is 100 μL / min.

[0013] (7) Preferably, the annealing temperature in (4) is 400°C.

[0014] Advantages of the present application:

[0015] (1) The MoS2 and ZnO used in the present application are bifunctional catalysts with light response and piezoelectric response capabilities, which effectively improve the utilization efficiency of light energy and mechanical energy and reduce the recombination probability of carriers.

[0016] (2) The catalyst prepared in the present application has ZnO existing in the interlayer space of MoS2, which promotes the ability of MoS2 to generate a piezoelectric field under the action of ultrasonic waves.

[0017] (3)The catalyst prepared in the present application can effectively utilize mechanical energy and light energy, and realize the conversion of lignin model compound-phenoxyphenethyl alcohol by 95.8% within 3h, to generate 83.8% of phenol and 71.4% of phenylethanone relative to the original phenoxyphenethyl alcohol concentration. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is the XRD pattern of MoS2 / ZnO catalyst in Examples 1-5 and Comparative Examples 1-2.

[0019] Figure 2 is the XPS pattern of MoS2 / ZnO catalyst in Examples 1-5 a: Mo3d, b: Zn2p, c: S2p, d: O1s.

[0020] Figure 3 is a: AC impedance spectrum, b: light response current, c: light response current under ultrasonic action, d: photoluminescence spectrum of MoS2 / ZnO catalyst in Examples 1-5 and Comparative Examples 1-2. DETAILED DESCRIPTION

[0021] The present application will be further described in detail below in conjunction with specific examples, which are an explanation of the present application rather than a limitation.

[0022] The preparation method of a MoS2 / ZnO catalyst for the combined conversion of lignin model compounds by sound and light according to the present application comprises the following steps, see Examples 1-5:

[0023] (1)Characterization of the catalyst: the synthesis of MoS2 / ZnO catalyst is determined by XRD and XPS, and the catalytic performance is verified by electrochemistry and photoluminescence spectrum.

[0024] Figure 1 : Compared with Comparative Example 1, the characteristic diffraction peak (002) of MoS2 in Examples 1-5 shifts to a small angle direction, indicating the successful insertion of Zn 2+ . The characteristic peaks of ZnO and MoS2 in Examples 1-5 are all retained, indicating that MoS2 and ZnO still maintain the basic crystal state. Figure 2 : The XPS pattern of the catalyst in Examples 1-5 shows that S vacancies appear in MoS2 after the formation of the heterostructure, while the basic MoS2 and ZnO morphology is still maintained. Figure 3The AC impedance spectra of the catalysts in Examples 1-5 were significantly lower than those of Comparative Examples 1-2, while being able to exhibit high photo-current response capability. After the ultrasonic wave was turned on, a larger current fluctuation occurred, indicating that the catalysts in Examples 1-5 were able to generate a piezoelectric field under the action of ultrasonic waves, inducing the movement of carriers in the heterojunction. The broad spectrum of photoluminescence indicated that the catalysts in Examples 1-5 were able to effectively prevent the recombination of photo-generated carriers.

[0025] (2) Catalyst performance test: The model compound phenoxyphenethyl alcohol was used as a lignin representative with a β-O-4 bond. The substrate 0.05 mmol / L was dissolved in acetonitrile: water (3:2) 50 mL, and the catalyst dosage was 1 mg / mL. The ultrasonic wave condition was 150 W 40 KHz, the light source distance from the quartz reactor was 20 cm, and the intensity was 1000 W / m 2 . During the reaction, a peristaltic pump and a thermostat were used to control the temperature at 25°C. When only photocatalysis was tested, magnetic stirring was used to provide stirring effect. After the reaction was completed, the catalyst was removed by centrifugation, and the conversion rate (Formula 1) and product selectivity (Formula 2) were tested.

[0026]

[0027]

[0028] wherein C0is the initial substrate concentration, C t is the substrate concentration at a certain time of the reaction. M t is the number of moles of the product, M c is the number of moles of the substrate.

[0029] Table 1 Conversion efficiency and selectivity of phenoxyphenethyl alcohol under the action of MoS2 / ZnO catalyst and sound-light combination

[0030]

[0031] Examples 1-5 and Comparative Examples 1-2 in Table 1 show that by constructing the MoS2 / ZnO catalyst, the conversion efficiency of phenoxyphenethyl alcohol is effectively improved. The conversion is mainly directed to the β-O-4 bond in phenoxyphenethyl alcohol, and after the chemical linkage is broken, phenol and phenylethanone are produced, while a small amount of phenoxyphenethyl alcohol is also converted to phenoxyphenylethanone during the conversion. Comparative Examples 3-4 and Example 3 show that the sound-light combination significantly improves the conversion efficiency of phenoxyphenethyl alcohol. In summary, the MoS2 / ZnO catalyst for sound-light combined conversion of lignin model compounds invented by us has good conversion efficiency and product selectivity.

[0032] Example 1:

[0033] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water: ethanol (3:7) with stirring at 600 rpm for 24 h.

[0034] 0.4508 g ZnAc was dissolved in 100 ml Mili-Q ultrapure water, stirred at 600 rpm for 24 h;

[0035] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h;

[0036] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated at 90 °C water bath for 2 h for in situ generation of ZnO in the interlayer space of MoS2, the ultrasonic condition was 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst;

[0037] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2 atmosphere;

[0038] (5) Catalyst performance test: Catalyst performance test was carried out according to the parameters in the specific embodiment (2).

[0039] Example 2:

[0040] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water: ethanol (3:7) with stirring at 600 rpm for 24 h. 0.9019 g ZnAc was dissolved in 100 ml Mili-Q ultrapure water, stirred at 600 rpm for 24 h;

[0041] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h;

[0042] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated at 90 °C water bath for 2 h for in situ generation of ZnO in the interlayer space of MoS2, the ultrasonic condition was 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst;

[0043] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2 atmosphere;

[0044] (5) Catalytic performance test: same as example 1 ;

[0045] Example 3:

[0046] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water: ethanol (3:7) with 600 rpm stirring for 24 h. 1.3529 g ZnAc was dissolved in 100 ml Mili-Q water with 600 rpm stirring for 24 h.

[0047] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h.

[0048] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated for 2 h at 90 °C water bath for in situ generation of ZnO in the interlayer space of MoS2, with ultrasonic conditions of 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst.

[0049] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2 atmosphere;

[0050] (5) Catalytic performance test: same as example 1 ;

[0051] Example 4:

[0052] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water: ethanol (3:7) with 600 rpm stirring for 24 h. 1.3529 g ZnAc was dissolved in 100 ml Mili-Q water with 600 rpm stirring for 24 h.

[0053] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h.

[0054] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated for 2 h at 90 °C water bath for in situ generation of ZnO in the interlayer space of MoS2, with ultrasonic conditions of 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst.

[0055] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2 atmosphere;

[0056] (5) Catalytic performance test: same as example 1;

[0057] Example 5:

[0058] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water: ethanol (3:7) with 600 rpm stirring for 24 h. 2.2542 g ZnAc was dissolved in 100 ml Mili-Q ultrapure water with 600 rpm stirring for 24 h.

[0059] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h.

[0060] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated for 2 h at 90 °C water bath for in-situ generation of ZnO in the interlayer space of MoS2, with ultrasonic conditions of 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst.

[0061] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2 atmosphere;

[0062] (5) Catalytic performance test: same as example 1;

[0063] Comparative Example 1:

[0064] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water: ethanol (3:7) with 600 rpm stirring for 24 h. 0 g ZnAc was dissolved in 100 ml Mili-Q ultrapure water with 600 rpm stirring for 24 h.

[0065] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h.

[0066] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated for 2 h at 90 °C water bath for in-situ generation of ZnO in the interlayer space of MoS2, with ultrasonic conditions of 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst.

[0067] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2atmosphere;

[0068] (5) Catalytic performance test: Same as Example 1;

[0069] Comparative Example 2:

[0070] (1) Stock solution preparation: MoS2 0 mg was dissolved in 100 mL water:ethanol (3:7) with 600 rpm stirring for 24 h. 2.2542 g ZnAc was dissolved in 100 ml Mili-Q ultrapure water with 600 rpm stirring for 24 h.

[0071] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h.

[0072] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated for 2 h at 90 °C water bath for in-situ generation of ZnO in the interlayer space of MoS2, with ultrasonic conditions of 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst.

[0073] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2atmosphere;

[0074] (5) Catalytic performance test: Same as Example 1;

[0075] Comparative Example 3:

[0076] (1) Stock solution preparation: MoS2 1000 mg was dissolved in 100 mL water:ethanol (3:7) with 600 rpm stirring for 24 h. 1.3529 g ZnAc was dissolved in 100 ml Mili-Q ultrapure water with 600 rpm stirring for 24 h.

[0077] (2) Zn 2+ Ion intercalation: ZnAc solution was dropped into the MoS2 suspension at 100 μL / min with continuous stirring for 24 h.

[0078] (3) Catalyst synthesis: 1.6 g NaOH and 0.5 g cetyltrimethylammonium bromide were added to the suspension in (2) and ultrasonicated for 2 h at 90 °C water bath for in-situ generation of ZnO in the interlayer space of MoS2, with ultrasonic conditions of 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60 °C to obtain the catalyst.

[0079] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2atmosphere;

[0080] (5) Catalyst performance test: Light source was not turned on, other parameters were the same as example 1;

[0081] Comparative Example 4:

[0082] (1) Preparation of raw material solution: 1000 mg of MoS2was dissolved in 100 mL of water: ethanol (3:7) and stirred at 600 rpm for 24 h. 1.3529 g of ZnAc was dissolved in 100 mL of Mili-Q ultrapure water and stirred at 600 rpm for 24 h.

[0083] (2) Zn 2+ Ion intercalation: The ZnAc solution was added dropwise to the MoS2suspension at a rate of 100 μL / min, and stirring was continued for 24 h.

[0084] (3) Catalyst synthesis: 1.6 g of NaOH and 0.5 g of cetyltrimethylammonium bromide were added to the suspension in (2), and ultrasonic treatment was performed at 90 °C for 2 h to generate ZnO in situ in the interlayer space of MoS2, the ultrasonic conditions were 150 W 40 KHz. The solid was collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times, and then dried at 60 °C to obtain the catalyst.

[0085] (4) Catalyst annealing: The solid catalyst was annealed at 400 °C for 3 h in a tube furnace under N2atmosphere;

[0086] (5) Catalyst performance test: Light source was not turned on, other parameters were the same as example 1;

[0087] The above examples are the preferred embodiments of the present application, but the embodiments of the present application are not limited to the above examples, and any changes, modifications, substitutions, combinations, simplifications made without departing from the spirit and principles of the present application are equivalent replacement methods, and are all included in the protection scope of the present application.

Claims

1. A method for the preparation of an acousto-optic catalyst for catalyzing the cleavage of ether bonds in lignin, characterized in that The following steps are followed: (1) Raw material solution preparation: MoS2 is dissolved in a certain volume of water: ethanol, the volume ratio of water: ethanol is 3:7, stirring at 600 rpm for 24 h; ZnAc is dissolved in a certain volume of Mili-Q ultrapure water, stirring at 600 rpm for 24 h; wherein the ratio of MoS2 to water: ethanol mixture is 1:100 g / mL, and the ratio of ZnAc to Mili-Q ultrapure water is 0.4508~2.2542:100 g / mL; (2) Zn 2+ Ion intercalation: ZnAc solution was added dropwise into the MoS2 suspension at a certain flow rate, and stirring was continued for 24 h; (3) Catalyst synthesis: NaOH and cetyltrimethylammonium bromide are added to the suspension in (2), and ultrasonic treatment is carried out at 90°C water bath for 2 h for in-situ generation of ZnO in the interlayer space of MoS2, the ultrasonic conditions are power: 150W, frequency: 40 KHz; the solid is collected by centrifugation at 10000 rpm / min for 10 min, washed with pure water for 3 times and dried at 60°C to obtain the catalyst; wherein the mass ratio of NaOH to MoS2 added in step (2) is 8:5, and the mass ratio of cetyltrimethylammonium bromide to MoS2 added in step (2) is 1:2; (4) Catalyst annealing: the solid catalyst is annealed at a certain temperature for 3 h in a tube furnace under N2 atmosphere.

2. A method for preparing an acousto-optic catalyst for breaking ether bonds in catalytic lignin according to claim 1, characterized by The flow rate of the ZnAc solution in step (2) is 100 μL / min.

3. A method for preparing an acousto-optic catalyst for breaking ether bonds in catalytic lignin according to claim 1, characterized by The annealing temperature in step (4) is 400°C.

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