Preparation of a bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol coupled with hydrogen evolution

Abstract

The application discloses a kind of preparation of bifunctional catalyst for photocatalytic oxidation furfuryl alcohol synchronously coupled hydrogen evolution, belong to photocatalytic technical field.The bifunctional catalyst is obtained by doping CdS and Ni / Co-BTC to obtain Ni / Co-BTC / CdS composite catalyst, wherein the mass ratio of CdS and composite catalyst Ni / Co-BTC / CdS is (0.2-0.8) ∶1.The application uses metal-organic framework structure of double metal Ni / Co-BTC as precursor and is doped with CdS to prepare composite material, under visible light irradiation, the composite material can simultaneously photocatalytic reduction water H2 and selective oxidation furfuryl alcohol, without any electron or hole sacrificial agent, and the catalytic effect is remarkable.

Description

Technical Field

[0001] This invention belongs to the field of photocatalysis technology, and particularly relates to the preparation of a bifunctional catalyst for the photocatalytic oxidation of furfuryl alcohol and simultaneous coupling of hydrogen evolution. Background Technology

[0002] In recent years, the conversion of biomass alcohols into their corresponding aldehydes has attracted considerable attention. Furfural, in particular, has been listed as an important bio-based chemical and a key chemical platform compound for the production of biofuels and high-value products. The conversion of biomass alcohols into their corresponding aldehydes mostly utilizes non-green solvents (such as benzotrifluoroether, DMF, or DMSO) and employs chemical or photochemical oxidation methods, using oxidants to achieve the oxidation of biomass alcohols. However, these methods often suffer from harsh reaction conditions, the need for high temperatures or precious metal catalysts, and low reactant conversion rates and product selectivity. Currently, there are increasing reports of photocatalytic oxidation of organic molecules to simultaneously produce hydrogen under mild conditions. Combining photocatalytic hydrogen production with biomass alcohol oxidation to simultaneously obtain high-value-added biomass aldehydes and hydrogen energy has significant research value.

[0003] Photocatalysis is a green catalytic method that has been used to produce hydrogen and oxygen from water splitting. While the half-reaction of reducing water to hydrogen using photogenerated electrons is relatively straightforward, the half-reaction of oxidizing water to oxygen using holes is often kinetically slow, which slows down or even inhibits the overall water splitting process. To address this issue, a common strategy is to use various sacrificial agents (such as lactic acid, formic acid, triethylamine, triethanolamine, and sodium sulfite) as hole sacrificial agents to accelerate hydrogen production. However, the use of hole sacrificial agents wastes the oxidation half-reaction and involves the use of toxic sacrificial agents. Summary of the Invention

[0004] To address the problems existing in the prior art, this invention proposes a bifunctional catalyst for the simultaneous photocatalytic oxidation of furfuryl alcohol and hydrogen evolution.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol with simultaneous hydrogen evolution is a Ni / Co-BTC / CdS composite catalyst obtained by doping CdS with Ni / Co-BTC.

[0007] Further, the mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS is (0.2-0.8):1. Preferably, it is 0.2:1, 0.4:1, 0.5:1, 0.6:1 and 0.8:1, more preferably 0.6:1.

[0008] This invention also provides a method for preparing the bifunctional catalyst described above for the photocatalytic oxidation of furfuryl alcohol and simultaneous coupling with hydrogen evolution, comprising the following steps:

[0009] Cd(CH3COO)2·2H2O and the Ni / Co-BTC were dispersed in deionized water to obtain solution A; Na2S·9H2O was dissolved in deionized water to obtain solution B; solution B was added dropwise to solution A to obtain a mixed solution; the mixture was stirred at room temperature, subjected to hydrothermal reaction, cooled, centrifuged to collect the solid product, washed, and dried to obtain a bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution, namely the Ni / Co-BTC / CdS composite catalyst.

[0010] Furthermore, the hydrothermal reaction is carried out at a temperature of 160°C for 24 hours.

[0011] This invention uses Cd(CH3COO)2·2H2O, Na2S·9H2O and Ni / Co-BTC as raw materials. By controlling the amount of Cd(CH3COO)2·2H2O and Na2S·9H2O, the doping amount of CdS in Ni / Co-BTC / CdS is regulated, thereby controlling the mass ratio of CdS to Ni / Co-BTC / CdS. This method enables CdS to grow on the surface of the precursor Ni / Co-BTC.

[0012] Further, the preparation method of Ni / Co-BTC includes the following steps: at room temperature, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, 1,3,5-pyromellitic acid and polyvinylpyrrolidone are dissolved in a mixed solvent and magnetically stirred to form a mixed solution; the mixed solution is subjected to a hydrothermal reaction, cooled, the solid is collected by centrifugation, washed, and dried to obtain a purple powder of Ni / Co-BTC.

[0013] Furthermore, the mass ratio of Ni(NO3)2·6H2O, Co(NO3)2·6H2O, 1,3,5-pyromellitic acid and polyvinylpyrrolidone is 0.144∶0.144∶0.1∶1; the mixed solvent is a mixture of water, anhydrous ethanol and DMF in a volume ratio of 1∶1∶1.

[0014] Furthermore, the mass ratio of Cd(CH3COO)2·2H2O, Ni / Co-BTC and Na2S·9H2O is (0.461-7.375):1:(0.4155-6.645).

[0015] The present invention also provides the application of the bifunctional catalyst described above for the photocatalytic oxidation of furfuryl alcohol with simultaneous hydrogen evolution in the photocatalytic oxidation of furfuryl alcohol with simultaneous hydrogen evolution.

[0016] Compared with the prior art, the present invention has the following advantages and technical effects:

[0017] This invention utilizes a bimetallic Ni / Co-BTC metal-organic framework as a precursor to dope CdS to prepare a composite material. The composite material leverages the unique structure and large specific surface area of ​​the bimetallic Ni / Co-BTC (35.94 m² as determined by BET testing). 2 ·g -1 The average pore size of the mesopores is 0.13 cm. 3 ·g -1 With its abundant catalytic active sites and the wide application of CdS in photocatalytic selective alcohol oxidation and other organic transformations, a composite catalyst with excellent catalytic performance was synthesized. The structure of the obtained composite catalyst provides a new approach for exploring efficient bifunctional semiconductor photocatalysts for hydrogen evolution and the oxidation of biomass alcohols. Attached Figure Description

[0018] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0019] Figure 1 The diagram shows the reaction apparatus, where 1-circulating water cooler; 2-condensate pipe (outlet); 3-condensate pipe (inlet); 4-magnetic stirrer; 5-photocatalytic reaction flask; 6-xenon lamp;

[0020] Figure 2 The conversion rate and hydrogen production distribution of the Ni / Co-BTC / CdS catalyst prepared in Examples 1-5, and the change of hydrogen production over time are shown in Figure (a).

[0021] Figure 3 Schematic diagram of the selective oxidation of furfuryl alcohol to furfural and hydrogen production mechanism of Ni / Co-BTC / CdS;

[0022] Figure 4 SEM images of CdS(a), Ni / Co-BTC(b), and Ni / Co-BTC / CdS-4(c) samples from Example 4. Detailed Implementation

[0023] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0024] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0025] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0026] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0027] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0028] This invention replaces hole sacrificial agents with organic compounds, oxidizes organic matter through the oxidation capacity of holes to achieve high-value conversion, and simultaneously uses the reducing capacity of electrons to reduce water to produce hydrogen, thus constructing a synergistic photocatalytic redox reaction system. This achieves the goal of fully utilizing the redox capacity of high-energy electrons and holes to achieve sustainable economic and social development.

[0029] Unless otherwise specified, "room temperature" in this invention refers to 25±2℃.

[0030] All raw materials used in the following embodiments of the present invention are commercially available.

[0031] The following embodiments are further illustrations of the technical solution of the present invention.

[0032] Example 1

[0033] 1) Preparation of Ni / Co-BTC samples

[0034] At room temperature, Ni(NO3)2·6H2O (0.432 g, 1.48 mmol), Co(NO3)2·6H2O (0.432 g, 1.48 mmol), 1,3,5-pyromellitic acid (0.3 g; 1.42 mmol), and polyvinylpyrrolidone (3 g) were dissolved in 30 mL of a solution of water / anhydrous ethanol / DMF = 1:1:1 (v / v / v). The solution was magnetically stirred for 1 h to form a mixed solution. The homogenized solution was transferred to a 100 mL hydrothermal reactor and reacted in an oven at 150 °C for 10 h. After natural cooling, the solid was collected by centrifugation and washed three times each with DMF and ethanol solutions. Finally, the solvent was removed in a vacuum drying oven at 60 °C to obtain a purple powdery Ni / Co-BTC sample.

[0035] 2) Preparation of Ni / Co-BTC / CdS samples

[0036] 0.0922g of Cd(CH3COO)2·2H2O and 0.2g of Ni / Co-BTC were dissolved and dispersed in 20mL of deionized water to obtain solution A; 0.0831g of Na2S·9H2O was weighed and dissolved in 20mL of deionized water to obtain solution B; solution B was added dropwise to solution A while stirring to form a mixed solution. The mixed solution was stirred at room temperature for 24 h, then reacted in a hydrothermal reactor at 160 °C for 24 h. After natural cooling, the solid product was collected by centrifugation and washed three times with ethanol. The resulting light yellow product was dried in a vacuum oven at 60 °C for 10 h, yielding a CdS to Ni / Co-BTC / CdS mass ratio of 0.2:1. Based on the added 0.346 mmol (0.0922 g) Cd(CH3COO)2·2H2O and 0.346 mmol (0.0831 g) Na2S·9H2O, the mass of 0.346 mmol of CdS produced was calculated to be 0.05 g. Calculate the ratio of the mass of CdS to the total mass of the catalyst, i.e., m... CdS / (m CdS +m Ni / Co-BTC A catalyst with a mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS of 0.2:1 was obtained (the same applies below), denoted as Ni / Co-BTC / CdS-1.

[0037] Example 2

[0038] Similar to Example 1, except that in the preparation of the Ni / Co-BTC / CdS sample, the amount of Cd(CH3COO)2·2H2O added was 0.249g and the amount of Na2S·9H2O added was 0.224g, that is, the mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS was 0.4∶1, which is denoted as Ni / Co-BTC / CdS-2.

[0039] Example 3

[0040] Similar to Example 1, except that in the preparation of the Ni / Co-BTC / CdS sample, the amount of Cd(CH3COO)2·2H2O added was 0.369g and the amount of Na2S·9H2O added was 0.332g, that is, the mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS was 0.5∶1, which is denoted as Ni / Co-BTC / CdS-3.

[0041] Example 4

[0042] Similar to Example 1, except that in the preparation of the Ni / Co-BTC / CdS sample, the amount of Cd(CH3COO)2·2H2O added was 0.553g and the amount of Na2S·9H2O added was 0.4986g, that is, the mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS was 0.6∶1, which is denoted as Ni / Co-BTC / CdS-4.

[0043] Example 5

[0044] Similar to Example 1, except that in the preparation of the Ni / Co-BTC / CdS sample, the amount of Cd(CH3COO)2·2H2O added was 1.475g and the amount of Na2S·9H2O added was 1.329g, that is, the mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS was 0.8∶1, which is denoted as Ni / Co-BTC / CdS-5.

[0045] Comparative Example 1 (Single Ni / Co-BTC)

[0046] A Ni / Co-BTC catalyst was prepared as follows: At room temperature, Ni(NO3)2·6H2O (0.432 g, 1.48 mmol), Co(NO3)2·6H2O (0.432 g, 1.48 mmol), 1,3,5-pyromellitic acid (0.3 g, 1.42 mmol), and polyvinylpyrrolidone (3 g) were dissolved in 30 mL of a solution of water / anhydrous ethanol / DMF = 1:1:1 (v / v / v). The solution was magnetically stirred for 1 h to form a mixed solution. The homogenized solution was transferred to a 100 mL hydrothermal reactor and reacted in an oven at 150 °C for 10 h. After natural cooling, the solid was collected by centrifugation and washed three times each with DMF and ethanol solutions. Finally, the solvent was removed in a vacuum drying oven at 60 °C to obtain a purple powdery Ni / Co-BTC sample.

[0047] Comparative Example 2 (Single CdS)

[0048] A CdS catalyst is prepared as follows: 0.532 g of Cd(CH3COO)2·2H2O is dissolved and dispersed in 20 mL of deionized water to obtain solution A; 0.48 g of Na2S·9H2O is weighed and dissolved in 20 mL of deionized water to obtain solution B; solution B is added dropwise to solution A while stirring to form a mixed solution. The mixed solution is stirred at room temperature for 24 h, and then reacted in a hydrothermal reactor at 160 °C for 24 h. After natural cooling, the solid product is collected by centrifugation, and the product is washed three times with ethanol. The resulting light yellow product is dried in a vacuum oven at 60 °C for 10 h to obtain CdS.

[0049] Application Example 1

[0050] Visible light-driven hydrogen evolution reaction (reaction apparatus diagram shown) Figure 1As shown, the Ni / Co-BTC / CdS (10 mg) prepared in Examples 1-5 was added to a photoreactor containing 10 mL of distilled water and cooled with circulating water at 25 °C (Cole-Parmer, 12101-36, USA). Argon gas was introduced for 10 minutes, and then 10 mM furfuryl alcohol was injected using a syringe. The reactor was placed under a magnetic stirrer (Chang Zhouyuexin, 78-1) and a light source. The light source was a 300 W xenon lamp (Perfectlight, PLS-SXE 300) with a cutoff wavelength >420 nm. Gas chromatography (Shimadzu GC-2014, Japan) was used with an FID detector and a 13-X molecular sieve column (4 nm × 2 m). The injection volume was 100 μL, and the carrier gas was Ar. After the photocatalytic reaction was completed, the catalyst was collected by centrifugation, washed with 3 times the volume of ethanol, and dried under vacuum at 60 °C for 10 h. The reaction solution was collected in a sample vial and filtered using a 0.22 μm filter membrane. Take 100.0 μL of the reaction solution and dilute to 1.0 mL with acetonitrile. Analyze the solution using a Shimadzu 2010 high-performance liquid chromatography system equipped with a PDA detector, including a binary pump and an autosampler. Use a Hypersil GOLD column (250 nm × 4.6 mm, 5 μm particle size). Maintain the column temperature at 35 °C. The mobile phase was (A) water and (B) acetonitrile, with elution conditions of: isocratic 35% B for 30 min, flow rate 0.8 mL / min. -1 The injection volume is 10 μL.

[0051] Figure 2 Photocatalytic oxidation conversion of furfuryl alcohol and hydrogen production distribution for different Ni / Co-BTC / CdS catalysts (1-5 on the horizontal axis represent sample numbers x). Figure 2 The results show that Ni / Co-BTC / CdS-4 exhibits the best photocatalytic oxidation performance. Furthermore, it was found that using water as the photocatalytic oxidation solvent and Ni / Co-BTC / CdS-4 as the photocatalyst, the conversion rate of furfuryl alcohol was 93%, the yield of furfural was 91%, and the yield of H2 after 7 hours of photocatalytic reaction was 1089 μmol·g⁻¹. -1 ·h -1 .

[0052] Figure 3 A diagram illustrating the mechanism of selective oxidation of furfuryl alcohol to furfural and hydrogen production using Ni / Co-BTC / CdS. The Ni / Co-BTC / CdS composite material exhibits good charge separation performance, and its spherical structure helps expose more catalytic active sites. Furthermore, the Ni / Co-BTC / CdS composite material photocatalyzes the oxidation of furfuryl alcohol, simultaneously undergoing both oxidation and reduction reactions, avoiding the use of sacrificial agents. This reduces the cost of the photocatalytic reaction and generates green energy (H2).

[0053] Figure 4 SEM images of CdS(a), Ni / Co-BTC(b), and Ni / Co-BTC / CdS-4(c) samples from Example 4. From... Figure 4 As can be seen in (a), CdS exhibits granular small crystals and agglomerated blocky morphology. From Figure 4 As can be seen in (b), Ni / Co-BTC is a spherical material with many short fiber-like hairs on the surface of the spherical crystals. Figure 4 (c) shows the morphology of Ni / Co-BTC / CdS-4. It can be seen that after the addition of CdS, some CdS particles are coated on the surface of the spherical Ni / Co-BTC, and the villous structure of Ni / Co-BTC is completely covered by granular CdS. When CdS grows on the surface of Ni / Co-BTC, the villous tentacles of Ni / Co-BTC effectively prevent CdS aggregation, increasing the surface activity of the catalyst and promoting the catalytic effect.

[0054] In summary, this invention grows CdS nanoparticles on the surface of Ni / Co-BTC to obtain a Ni / Co-BTC / CdS composite material and realizes a bifunctional catalytic method. Under visible light irradiation, the Ni / Co-BTC / CdS composite material can simultaneously photocatalytically reduce water to H2 and selectively oxidize furfuryl alcohol without requiring any electron or hole sacrificial agents. When water is used as the photocatalytic oxidation solvent, photogenerated electrons reduce hydrogen protons in water to H2, and furfuryl alcohol is oxidized to furfural under the action of holes. The conversion rate of furfuryl alcohol is 93%, the yield of furfural is 91%, and the yield of H2 after 7 hours of reaction is 1089 μmol·g. -1 ·h -1 The photocatalytic oxidation of furfuryl alcohol using a single Ni / Co-BTC and CdS material yielded no detected redox products, furfural and hydrogen. However, the composite catalyst, Ni / Co-BTC / CdS, exhibited significantly enhanced catalytic performance. This invention provides a new approach for the preparation and mechanistic study of bifunctional catalysts.

[0055] The above are merely preferred embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A bifunctional catalyst for the photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution, characterized in that, The bifunctional catalyst is a Ni / Co-BTC / CdS composite catalyst obtained by doping CdS with Ni / Co-BTC; wherein the Ni / Co-BTC is spherical and its surface has fibrous hairs; the CdS is coated on the hairy surface of the Ni / Co-BTC in the form of particles; The preparation method of the bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution includes the following steps: dispersing Cd(CH3COO)2·2H2O and Ni / Co-BTC in deionized water to obtain solution A; dissolving Na2S·9H2O in deionized water to obtain solution B; adding solution B dropwise to solution A to obtain a mixed solution; stirring at room temperature, hydrothermal reaction, cooling, centrifuging to collect the solid product, washing, and drying to obtain the bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution, namely the Ni / Co-BTC / CdS composite catalyst; The method for preparing the Ni / Co-BTC includes the following steps: at room temperature, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, 1,3,5-pyromellitic acid and polyvinylpyrrolidone are dissolved in a mixed solvent and magnetically stirred to form a mixed solution; the mixed solution is subjected to a hydrothermal reaction, cooled, the solid is collected by centrifugation, washed, and dried to obtain a purple powder Ni / Co-BTC.

2. The bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution according to claim 1, characterized in that, The mass ratio of CdS to the composite catalyst Ni / Co-BTC / CdS is (0.2-0.8):

1.

3. A method for preparing a bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution as described in any one of claims 1-2, characterized in that, Includes the following steps: Cd(CH3COO)2·2H2O and the Ni / Co-BTC were dispersed in deionized water to obtain solution A; Na2S·9H2O was dissolved in deionized water to obtain solution B; solution B was added dropwise to solution A to obtain a mixed solution; the mixture was stirred at room temperature, subjected to hydrothermal reaction, cooled, centrifuged to collect the solid product, washed, and dried to obtain a bifunctional catalyst for photocatalytic oxidation of furfuryl alcohol and simultaneous hydrogen evolution, namely the Ni / Co-BTC / CdS composite catalyst; The method for preparing the Ni / Co-BTC includes the following steps: at room temperature, Ni(NO3)2·6H2O, Co(NO3)2·6H2O, 1,3,5-pyromellitic acid and polyvinylpyrrolidone are dissolved in a mixed solvent and magnetically stirred to form a mixed solution; The mixed solution was subjected to a hydrothermal reaction, cooled, centrifuged to collect the solid, washed, and dried to obtain a purple powder of Ni / Co-BTC.

4. The preparation method according to claim 3, characterized in that, The hydrothermal reaction was carried out at a temperature of 160°C for 24 hours.

5. The preparation method according to claim 3, characterized in that, In the process of preparing the Ni / Co-BTC, the mass ratio of Ni(NO3)2·6H2O, Co(NO3)2·6H2O, 1,3,5-pyromellitic acid and polyvinylpyrrolidone is 0.144∶0.144∶0.1∶1.

6. The preparation method according to claim 3, characterized in that, In the process of preparing the Ni / Co-BTC, the mixed solvent is water, anhydrous ethanol and DMF mixed in a volume ratio of 1:1:

1.

7. The preparation method according to claim 3, characterized in that, The mass ratio of Cd(CH3COO)2·2H2O, Ni / Co-BTC and Na2S·9H2O is (0.461-7.375):1:(0.4155-6.645).

8. The application of a bifunctional catalyst as described in any one of claims 1-2 for the photocatalytic oxidation of furfuryl alcohol with simultaneous hydrogen evolution in the photocatalytic oxidation of furfuryl alcohol with simultaneous hydrogen evolution.

Images