Preparation of monatomic graphene type photo-thermal catalyst and application of monatomic graphene type photo-thermal catalyst in catalyzing aldose to produce ketose

Abstract

The invention discloses preparation of a monatomic graphene type photo-thermal catalyst and application of the monatomic graphene type photo-thermal catalyst in catalyzing aldose to produce ketose, and the preparation comprises the following steps: loading a monatomic precursor (X) on a graphene type carbon material (GT) by adopting a solution impregnation method, further reducing the monatomic precursor into a corresponding monatomic (Y) by adopting a continuous oxidation-reduction method, the monatomic graphene type photo-thermal catalyst is obtained, and the monatomic graphene type photo-thermal catalyst is expressed as Ysg / GT. The catalyst is used for catalyzing other different aldoses (maltose, glyceraldehyde, erythritol and xylose) to produce corresponding ketose, the catalyst shows good catalytic activity and photo-thermal performance, and the ketose yield is larger than 50%. Finally, in the reusability research of the catalyst, the catalyst is found to have good activity and structural stability, the chemical equilibrium limit of the reversible reaction is broken through, the reaction rate is increased, and the catalyst can help to develop an efficient and green catalyst to open up a new way for the reversible reaction process.

Description

Technical Field

[0001] The invention relates to the preparation of a single-atom graphene type photothermal catalyst and its application in catalyzing aldose to produce ketose, and belongs to the field of heterogeneous catalysis. Background Art

[0002] Biomass is the most abundant, extensive and clean renewable carbon resource on earth, with a global production of 170 billion tons per year. Converting it into high-value chemicals and biofuels is potential and attractive, as people's awareness of environmental protection and sustainable energy development increases. Biomass-derived glucose is the cheapest and only abundant monosaccharide in nature. Isomerizing it to fructose is a key step in converting biomass into high-value chemicals and biofuels. Fructose not only acts as a sweetener in food, but it is also a key intermediate for a variety of value-added chemicals and biofuels, such as lactic acid, levulinic acid, gluconic acid, sorbitol, 5-hydroxymethylfurfural and ethoxymethylfurfural (EMF). If fructose is used as a starting material to produce value-added chemicals and biofuels, the production process will be simplified, making it easier to realize the resource utilization of biomass energy. However, fructose in nature is found in most fruits and vegetables, and it is difficult to directly extract and mass-produce it from vegetables and fruits. Therefore, fructose is mainly derived from the production of high fructose corn syrup (HFCS) by catalyzing the isomerization of glucose by immobilized glucose / xylose isomerase in aqueous phase, and the global production is as high as 14 million metric tons per year, which also highlights the importance of fructose to human development. This catalytic production method has been industrialized for more than half a century. It requires an adapted pH and mild conditions to achieve a fructose yield of 42%, close to thermodynamic equilibrium. However, the enzyme catalytic process also faces some inevitable challenges, such as high temperatures (> 60°C) that will inactivate the enzyme and the need to carefully control the purity of the feed, flow rate and pH range. In view of this, from an economic point of view, the enzyme-catalyzed production of fructose still faces the challenges of high cost and low fructose yield.

[0003] Compared with enzymes, alkaline / acid chemical catalysts have lower costs, wider temperature and pH operation requirements, and lower feed requirements. Therefore, acid / base catalysts are widely used in the study of glucose isomerization to fructose and are considered to replace enzyme catalysts. The yield of glucose isomerization to fructose catalyzed by homogeneous (Ca(OH)2, KOH, piperazine and ethylenediamine) and heterogeneous base catalysts (hydrotalcite, metal oxides and alkaline metal salts, cation exchange molecular sieves, etc.) is generally low (30-40%), which is attributed to the degradation of sugar solutions in alkaline environments and the production of more than 50 different by-products. Homogeneous acids (CrCl3, SnCl4 and AlCl3) have the ability to catalyze glucose isomerization, but the effect of catalytic production of fructose is not ideal (4.7-26.3%) and face problems with catalyst separation and reusability. In contrast, heterogeneous acid catalysts have become the focus of research and are mainly concentrated on zeolites (Sn-Beta, H-USY zeolite, Sn-MCM-41, Sn-MWW, Sn-MFI, NaY), but such catalysts are challenging to commercialize in terms of synthesis and cost. At the same time, the isomerization of glucose to fructose in the aqueous phase is a typical reversible reaction that requires thermal energy as a driving force and the reaction is controlled by thermodynamic equilibrium, which makes it difficult for the isomerization process to break through thermodynamic equilibrium (30-40%). Therefore, some researchers have used organic solvents (1-butanol, ethanol, DMF and DMSO) instead of aqueous solvents to maximize the fructose yield (51-56%). However, the cost of this method is the complication of the downstream fructose separation and purification process and the increased risk of food safety. Summary of the invention

[0004] The technical problem to be solved by the present invention is: in view of the problems of high energy consumption, low ketose yield, slow reaction rate and use of organic solvents in the reversible reaction system of traditional heat-driven catalysis of aldose to produce ketose, a single-atom graphene-type photothermal catalyst, its preparation and its application in catalyzing the production of ketose from aldose are proposed.

[0005] The technical solution of the present invention is: a method for preparing a single-atom graphene type photothermal catalyst, comprising the following steps: firstly loading a single-atom precursor (X) on a graphene type carbon material (GT) by a solution impregnation method, and further reducing the single-atom precursor to a corresponding single atom (Y) by a continuous oxidation-reduction method, thereby obtaining a single-atom graphene type photothermal catalyst, expressed as Ysg / GT.

[0006] The preparation method of the graphene-type carbon material (GT) is as follows: the biomass powder is soaked in dilute hydrochloric acid for 1 to 12 hours at 25 to 120°C and then freeze-dried for 6 to 12 hours; the pretreated biomass is then pyrolyzed under an inert atmosphere (N2 and Ar) for 1 to 9 hours at 300 to 1200°C to obtain the graphene-type carbon material (GT).

[0007] The biomass includes: crops, crop wastes, wood, wood wastes and animal excrement; the concentration of the dilute hydrochloric acid is 0.5-15%.

[0008] The single atom (Y) includes potassium (K), magnesium (Mg), calcium (Ca), titanium (Ti), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), silver (Ag), palladium (Pd), platinum (Pt), and gold (Au).

[0009] The single atom precursor (X) includes potassium nitrate (KNO3), potassium sulfate (K2SO4), potassium chloride (KCl), potassium hydroxide (KOH), potassium oxide (K2O), magnesium chloride (MgCl2), magnesium nitrate (Mg(NO3)2), calcium nitrate (Ca(NO3)2), calcium chloride (CaCl2), calcium oxalate (CaC2O4), calcium carbonate (CaCO3), calcium oxide (CaO), titanic acid (TiO2·xH2O), titanium dioxide (TiO2), ammonium chromate ((NH4)2CrO4), chromium chloride (CrCl3), iron chloride (FeCl3), iron nitrate (Fe(NO3)3), hexadecene Cobalt chloride (CoCl2·6H2O), cobalt nitrate (Co(NO3)2), nickel chloride (NiCl2), nickel nitrate (Ni(NO3)2), nickel sulfate hexahydrate (NiSO4·6H2O), copper nitrate (Cu(NO3)2), copper chloride (CuCl2), zinc chloride (ZnCl2), zinc nitrate (Zn(NO3)2), cadmium chloride (CdCl2), cadmium nitrate (Cd(NO3)2), silver nitrate (AgNO3), silver chloride (AgCl), palladium dichloride (PdCl2), tetrachloropalladium(II) acid (H2PdCl4), gold chloride (AuCl) and gold chloride (AuCl3).

[0010] The mass ratio of the GT to the single atom precursor is 0.01 to 20 wt.%.

[0011] The method for preparing a single-atom graphene-type photothermal catalyst is as follows: a single-atom precursor is dissolved in an ethanol aqueous solution, GT is added, and the mixture is stirred at room temperature for 1 to 24 hours, and then the mixed suspension is vacuum dried at 80°C for 6 to 12 hours, and then calcined at 300 to 1200°C in an inert atmosphere (N2 and Ar) for 1 to 9 hours to obtain a graphene-type photothermal catalyst in which isolated single atoms and adjacent single atoms coexist, which is represented by Ysg / GT.

[0012] The application of the single-atom graphene-type photothermal catalyst in catalyzing glucose isomerization to produce fructose.

[0013] A method for producing fructose by catalyzing glucose isomerization using a single-atom graphene-type photothermal catalyst is as follows: the single-atom graphene-type photothermal catalyst is used as a glucose substrate, and the catalyst is added at a rate of 0.01 to 2 g of the single-atom graphene-type catalyst / 0.5 g of glucose, and the catalyst is heated at 500 to 4000 W m -2 React under strong light for 10 to 240 minutes.

[0014] After the catalytic reaction of the catalyst is completed, the catalyst is separated from the product, washed with methanol and deionized water respectively, and dried before being used again to catalyze glucose isomerization to produce fructose.

[0015] The single-atom graphene-type photothermal catalyst is used to catalyze the isomerization of different aldoses to produce ketose.

[0016] A method for catalyzing different aldoses to produce ketose using a single-atom graphene-type photothermal catalyst is as follows: the single-atom graphene-type photothermal catalyst catalyzes different aldoses to produce ketose, and the catalyst is added according to 0.01 to 2 g of single-atom graphene-type photothermal catalyst / 0.5 g of aldose, and the catalyst is heated at 500 to 4000 W m -2 React under strong light for 10 to 240 minutes.

[0017] The different aldoses include maltose, glyceraldehyde, erythrose and xylose.

[0018] Beneficial effects of the present invention: 1. The present invention adopts a solution impregnation method to first load the single-atom precursor (X) on the graphene-type carbon material (GT), and further calcined at 900°C for 3h under the protection of an inert atmosphere (N2 and Ar). In this process, the single-atom precursor is reduced to the corresponding single atom (Y) by a continuous oxidation-reduction method, and the corresponding single-atom graphene-type photothermal catalyst is obtained. The problems of high energy consumption of glucose isomerization to fructose, low fructose yield, slow reaction rate and use of organic solvents have been successfully overcome.

[0019] 2. The prepared single-atom graphene photothermal catalyst has good photothermal conversion performance, 1000W m -2 Under the intensity of sunlight, its surface temperature can reach about 85℃.

[0020] 3. The prepared single-atom graphene photothermal catalyst has good catalytic activity under room temperature. -2 When the reaction time was 30 min and the catalyst dosage was 1.2 mol%, the fructose yield was > 65%.

[0021] 4. The prepared single-atom graphene-type photothermal catalyst is a heterogeneous type. After the reaction, the catalyst can be recovered by a simple centrifugation method and used in the next catalytic reaction. After being reused 5 times, the fructose yield is still >60%, which reflects the strategy of high efficiency, green, stable and sustainable development.

[0022] 5. The prepared single-atom graphene photothermal catalyst has good universal applicability. When maltose, glyceraldehyde, erythrose and xylose are used as substrates and the light intensity is 1000W m -2 When the reaction time was 30 min and the catalyst dosage was 1.2 mol%, the ketose yield was greater than 50%.

[0023] 6. The present invention solves the problems of high energy consumption, complex production process, low selectivity of aldose conversion, low sugar yield, slow reaction rate and use of organic solvents in the traditional high-temperature driven reversible reaction system for aldose to ketose, and improves the safety and economy of the production system. -2 Within the range of light intensity, aldose can be efficiently converted into ketose. After the catalytic reaction is completed, the catalyst can be directly reused after centrifugation, washing and drying, realizing the recycling of single-atom graphene photothermal catalysts. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The HPLC detection spectrum of glucose and fructose in Example 1;

[0025] Figure 2 This is a graph showing the yield of glucose to fructose catalyzed by K-single-atom graphene-type photothermal catalyst in Example 1 at different catalyst dosages;

[0026] Figure 3 This is a graph showing the yield of maltulose produced from maltose by the K-single-atom graphene-type photothermal catalyst of Example 2 at different reaction times;

[0027] Figure 4 This is a graph showing the yield of glyceraldehyde to dihydroxyacetone produced by K-single-atom graphene-type photothermal catalyst at different reaction times in Example 3;

[0028] Figure 5 This is a graph showing the yield of erythrulose produced by catalyzing erythrose with the K-single-atom graphene-type photothermal catalyst in Example 4 at different reaction times;

[0029] Figure 6 This is a graph showing the yield of xylulose produced by catalyzing xylose with the K-single-atom graphene-type photothermal catalyst of Example 5 at different reaction times;

[0030] Figure 7This is a graph showing the yield of glucose to fructose produced by the Cr-single-atom graphene-type photothermal catalyst in Example 6 at different catalyst dosages;

[0031] Figure 8 This is a graph showing the yield of glucose to fructose produced by Ag-single-atom graphene-type photothermal catalyst at different catalyst dosages in Example 7;

[0032] Fig. 9 This is a graph showing the yield of glucose to fructose catalyzed by Au-single-atom graphene-type photothermal catalyst in Example 8 at different catalyst dosages;

[0033] Fig.10 Schematic diagram of catalyst preparation for this application. DETAILED DESCRIPTION

[0034] The technical scheme of the present invention is further described in detail below in conjunction with the embodiments, but they are not intended to limit the present invention.

[0035] Example 1

[0036] 1. Preparation of K-atom graphene-type photothermal catalyst:

[0037] The corn stalks were washed, dried and crushed for later use. 4 g of stalks were soaked in 25 mL of dilute hydrochloric acid for 5 h at 60 ° C and then freeze-dried for 8 to 12 h. Subsequently, the pretreated stalks were placed in a horizontal tubular muffle furnace and pyrolyzed at 900 ° C for 3 h under N2 atmosphere protection to obtain graphene-type carbon materials (GT).

[0038] The KNO3 precursor was loaded on the graphene-type carbon material (GT) by solution impregnation method. The general experimental steps were to take 0.04g KNO3 and dissolve it in 50mL 50% ethanol solution, then add 0.5g GT and mix and stir for 24h at room temperature. The mixed suspension was then vacuum dried at 80℃ for 12h to obtain KNO3-loaded solid, which was then placed in a horizontal tubular muffle furnace and calcined at 900℃ in N2 atmosphere for 3h to obtain isolated / ortho-K single-atom graphene-type catalyst, which was expressed as Ksg / GT.

[0039] 2. Catalyst performance test

[0040] In a 15 mL Ace pressure tube, add 0.5 g glucose, a 0.5 cm magnetic stir bar, and a certain amount of Kg / GT catalyst (n Ksg / GT / n 葡萄糖 =1.2 mol%) and 5 mL of deionized water and sealed the tube. -2After 60 minutes of reaction under simulated sunlight, the reaction tube was quickly quenched. Finally, the catalyst and fructose mixed solution were separated by centrifugation. The catalyst was used for the next recycling. The fructose mixed solution was diluted 2500 times with deionized water and the fructose yield and glucose conversion rate were detected by high performance liquid chromatography (HPLC).

[0041] 3. High performance liquid chromatography (HPLC) detection method

[0042] The fructose mixed solution diluted 2500 times was filtered with a Millipore filter (pore size 0.45 μm) and used for high performance liquid chromatography (HPLC, 1200 Agilent system), a refractive index detector (RID) and an Aminex HPX-87H column (300×7.8 mm, Bio-Rad) for detection. A 5 mM sulfuric acid solution was used as the mobile phase at a flow rate of 0.5 mL / min. Each experiment was repeated three times to obtain error bars. Glucose conversion rate, fructose selectivity, fructose yield and carbon balance were calculated as follows:

[0043] Conversion rate (%) = (n [葡萄糖]1 -n [葡萄糖]2 ) / (n [葡萄糖]1 )×100%

[0044] Selectivity (%) = (n [果糖] ) / (n [葡萄糖]1 -n [葡萄糖]2 )×100%

[0045] Fructose yield (%) = (n [果糖] ) / (n [葡萄糖]1 )×100%

[0046] Carbon balance (%) = (n [葡萄糖]2 +n [果糖] ) / (n [葡萄糖]1 )×100%.

[0047] 4. Study on the reusability of catalyst

[0048] The stability of structure and activity is a very important reference parameter for evaluating the catalytic performance of heterogeneous catalysts, so the reusability of heterogeneous catalysts was studied. After each use, the catalyst was separated by a centrifuge (8000rpm) to recover the catalyst, and then washed with deionized water and ethanol alternately for 3 times and dried in a vacuum drying oven at 80°C for 12h. Finally, it was reused 6 times and then placed in a horizontal tubular muffle furnace and activated at 900°C for 1h under N2 atmosphere.

[0049] Example 2

[0050] 1. Preparation of K-atom graphene-based photothermal catalysts:

[0051] Same as Example 1.

[0052] 2. Catalytic performance test

[0053] Substrate glucose was replaced by maltose, and the other procedures were the same as in Example 1. The yield of maltulose was 52.5%.

[0054] 3. High performance liquid chromatography (HPLC) detection method

[0055] Same as Example 1.

[0056] 4. Study on the reusability of catalyst

[0057] Same as Example 1.

[0058] Example 3

[0059] 1. Preparation of K-atom graphene-based photothermal catalysts:

[0060] Same as Example 1.

[0061] 2. Catalytic performance test

[0062] Substrate glucose was replaced by glyceraldehyde, and the other procedures were the same as in Example 1. The yield of dihydroxyacetone was 51.7%.

[0063] 3. High performance liquid chromatography (HPLC) detection method

[0064] Same as Example 1.

[0065] 4. Study on the reusability of catalyst

[0066] Same as Example 1.

[0067] Example 4

[0068] 1. Preparation of K-atom graphene-based photothermal catalysts:

[0069] Same as Example 1.

[0070] 2. Catalytic performance test

[0071] Substrate glucose was replaced by erythrose, and the other procedures were the same as in Example 1. The yield of erythrulose was 53.3%.

[0072] 3. High performance liquid chromatography (HPLC) detection method

[0073] Same as Example 1.

[0074] 4. Study on the reusability of catalyst

[0075] Same as Example 1.

[0076] Example 5

[0077] 1. Preparation of K-atom graphene-based photothermal catalysts:

[0078] Same as Example 1.

[0079] 2. Catalytic performance test

[0080] Substrate glucose was replaced by xylose, and the other procedures were the same as in Example 1. The yield of xylulose was 62.8%.

[0081] 3. High performance liquid chromatography (HPLC) detection method

[0082] Same as Example 1.

[0083] 4. Study on the reusability of catalyst

[0084] Same as Example 1.

[0085] Example 6

[0086] 1. Preparation of Cr-single-atom graphene-type photothermal catalyst:

[0087] KNO3 was replaced by CrCl2, and the rest was the same as in Example 1.

[0088] 2. Catalytic performance test

[0089] The same method as in Example 1 was used, but the yield of fructose was 71.4%.

[0090] 3. High performance liquid chromatography (HPLC) detection method is the same as in Example 1.

[0091] 4. Study on the reusability of catalyst

[0092] Same as Example 1.

[0093] Example 7

[0094] 1. Preparation of Ag-single-atom graphene-type photothermal catalyst:

[0095] KNO3 was replaced by AgNO3, and the rest was the same as in Example 1.

[0096] 2. Catalytic performance test

[0097] The same method as in Example 1 was used, but the yield of fructose was 66.5%.

[0098] 3. High performance liquid chromatography (HPLC) detection method is the same as in Example 1.

[0099] 4. Study on the reusability of catalyst

[0100] Same as Example 1.

[0101] Example 8

[0102] 1. Preparation of Au-single-atom graphene-type photothermal catalyst:

[0103] KNO3 was replaced by AuCl3, and the rest was the same as in Example 1.

[0104] 2. Catalytic performance test

[0105] The same method as in Example 1 was used, but the yield of fructose was 72.3%.

[0106] 3. High performance liquid chromatography (HPLC) detection method is the same as in Example 1.

[0107] 4. Study on the reusability of catalyst

[0108] Same as Example 1.

Claims

1. A method for preparing a single-atom graphene-type photothermal catalyst, characterized in that: The method comprises the following steps: firstly loading a single atom precursor (X) on a graphene-type carbon material (GT) by a solution impregnation method, and further reducing the single atom precursor to a corresponding single atom (Y) by a continuous oxidation-reduction method, thereby obtaining a single atom graphene-type photothermal catalyst, which is expressed as Ysg / GT.

2. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 1, characterized in that: The preparation method of the graphene-type carbon material (GT) is as follows: the biomass powder is soaked in dilute hydrochloric acid for 1 to 12 hours at 25 to 120° C. and then freeze-dried for 6 to 12 hours; the pretreated biomass is then pyrolyzed under an inert atmosphere for 1 to 9 hours at 300 to 1200° C. to obtain the graphene-type carbon material (GT).

3. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 2, characterized in that: The biomass includes: crops, crop wastes, wood, wood wastes and animal excrement; the concentration of the dilute hydrochloric acid is 0.5-15%.

4. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 1, characterized in that: The single atom (Y) includes potassium (K), magnesium (Mg), calcium (Ca), titanium (Ti), chromium (Cr), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), cadmium (Cd), silver (Ag), palladium (Pd), platinum (Pt), and gold (Au).

5. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 1, characterized in that: The single atom precursor (X) includes potassium nitrate (KNO3), potassium sulfate (K2SO4), potassium chloride (KCl), potassium hydroxide (KOH), potassium oxide (K2O), magnesium chloride (MgCl2), magnesium nitrate (Mg(NO3)2), calcium nitrate (Ca(NO3)2), calcium chloride (CaCl2), calcium oxalate (CaC2O4), calcium carbonate (CaCO3), calcium oxide (CaO), titanic acid (TiO2·xH2O), titanium dioxide (TiO2), ammonium chromate ((NH4)2CrO4), chromium chloride (CrCl3), iron chloride (FeCl3), iron nitrate (Fe(NO3)3), hexadecene (TiO2·xH2O), chromium chloride (CrCl3), ferric chloride (FeCl3), ferric nitrate (Fe(NO3)3), Cobalt chloride (CoCl2·6H2O), cobalt nitrate (Co(NO3)2), nickel chloride (NiCl2), nickel nitrate (Ni(NO3)2), nickel sulfate hexahydrate (NiSO4·6H2O), copper nitrate (Cu(NO3)2), copper chloride (CuCl2), zinc chloride (ZnCl2), zinc nitrate (Zn(NO3)2), cadmium chloride (CdCl2), cadmium nitrate (Cd(NO3)2), silver nitrate (AgNO3), silver chloride (AgCl), palladium dichloride (PdCl2), tetrachloropalladium(II) acid (H2PdCl4), gold chloride (AuCl) and gold chloride (AuCl3).

6. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 1, characterized in that: The mass ratio of the GT to the single atom precursor is 0.01-20wt.%.

7. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 1, characterized in that: The specific method is: take a single atom precursor and dissolve it in an ethanol aqueous solution, then add GT and mix and stir at room temperature for 1 to 24 hours, then vacuum dry the mixed suspension at 80°C for 6 to 12 hours, and calcine it at 300 to 1200°C in an inert atmosphere for 1 to 9 hours to obtain a graphene-type photothermal catalyst in which isolated single atoms and adjacent single atoms coexist, which is represented by Ysg / GT.

8. Use of a single-atom graphene-type photothermal catalyst as claimed in any one of claims 1 to 7 in catalyzing glucose isomerization to produce fructose.

9. Use of a single-atom graphene-type photothermal catalyst as claimed in any one of claims 1 to 7 in catalyzing the isomerization of different aldoses to produce ketose.

10. The method for preparing a single-atom graphene-type photothermal catalyst according to claim 9, characterized in that: The different aldoses include maltose, glyceraldehyde, erythrose and xylose.

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