A Cu 0.1 CeO2@LDO photocatalyst, preparation method and application thereof

Abstract

The application relates to the technical field of photo-thermal catalysis, in particular to a Cu 0.1 CeO2@LDO photocatalyst and a preparation method and application thereof. The application aims at the problems of a complex existing catalytic system and low conversion rate, and a Cu 0.1 CeO2@LDO photocatalyst is prepared through a hydrothermal and ethanol immersion method, cellulose is selectively converted into lactic acid and formic acid through photo-thermal catalysis technology. The prepared Cu 0.1 CeO2@LDO photocatalyst has good chemical stability and photo-catalytic performance, can realize high conversion rate and product selectivity, and has the advantages of greenness, simplicity and high efficiency compared with traditional thermal catalysis and enzyme catalysis, and has good application prospect.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of photo-thermal catalysis, in particular to a Cu 0.1 CeO2@LDO photocatalyst and a preparation method and application thereof. BACKGROUND

[0002] With the increasing seriousness of global ecological environmental pollution and energy shortage, people have begun to seek more environmentally friendly and sustainable energy. Cellulose, as the most abundant organic polymer on earth, widely exists in biomass resources, has good biodegradability and regenerability. Converting cellulose into high-value chemicals, especially lactic acid and formic acid, can provide sustainable raw material sources for the energy and chemical industries. Among them, lactic acid is not only an important bio-based chemical, widely used in food, medicine and biological materials, etc., and formic acid has good chemical properties and environmental friendliness, and has wide application prospects in the fields of agriculture and chemical industry.

[0003] The current known cellulose conversion methods mainly include enzymatic hydrolysis, electrochemical reduction and thermochemical methods, etc., but these technologies often require high energy input or complex catalyst systems. In contrast, photo-thermal catalysis, as an emerging conversion technology, can realize the effective conversion of cellulose at a mild temperature and environmental condition by exciting the catalyst with light energy. This process not only improves the selectivity of the reaction, but also significantly reduces the energy consumption and cost.

[0004] Therefore, it has important scientific significance and economic value to develop efficient and selective photo-thermal catalysts and optimize the cellulose conversion conditions. SUMMARY

[0005] The application provides a Cu 0.1 CeO2@LDO photocatalyst and a preparation method and application thereof. In view of the problems of complex existing catalytic system and low conversion rate, the Cu 0.1 CeO2@LDO photocatalyst is prepared by a hydrothermal and ethanol immersion method, and cellulose is selectively converted into lactic acid and formic acid by photo-thermal catalysis technology. The Cu 0.1 CeO2@LDO photocatalyst prepared by the application has good chemical stability and photocatalytic performance, can realize high conversion rate and product selectivity, and compared with traditional thermal catalysis and enzyme catalysis, the method has the advantages of green, simple and efficient, and has good application prospect.

[0006] In order to achieve the above purpose, the application provides the following technical scheme:

[0007] The application provides a Cu 0.1 The preparation method of the Cu

[0008] S1. Magnesium salt, aluminum salt, fumaric acid, and urea were dissolved in water, stirred, and then transferred to a high-pressure hydrothermal reactor for hydrothermal reaction to obtain a three-dimensional hydrangea-shaped hydrotalcite;

[0009] S2. After dissolving cerium salt, copper salt and sodium hydroxide in water, stir at 60-80°C for 18-24h to obtain Cu 0.1 CeO2 precursor;

[0010] S3. Disperse the three-dimensional hydrangea-shaped hydrotalcite obtained in S1 in water, add anhydrous ethanol and the Cu obtained in S2 0.1 CeO2 precursor, stirred and mixed, and then dried to obtain a mixture powder, and the mixture powder was calcined to obtain Cu 0.1 CeO2@LDO photocatalyst.

[0011] This application composite three-dimensional hydrangea-shaped hydrotalcite and Cu 0.1 CeO2 precursor, calcined to obtain Cu 0.1 CeO2@LDO. With the help of Cu 0.1 The large surface area of ​​CeO2@LDO provides more active sites to achieve more efficient photothermal catalysis of cellulose to produce lactic acid and formic acid. 0.1 The CeO2 precursor is obtained by screening at a specific temperature to ensure the characteristics of the composite material.

[0012] Preferably, after the hydrothermal reaction in S1, freeze-drying is performed for 48 hours to obtain the three-dimensional hydrangea-shaped hydrotalcite.

[0013] Preferably, in S1, the temperature of the hydrothermal reaction is 110-120° C., and the time of the hydrothermal reaction is 6-12 hours.

[0014] More preferably, the temperature of the hydrothermal reaction is 110° C., and the time of the hydrothermal reaction is 10 h.

[0015] Preferably, in S1, the magnesium salt is magnesium nitrate, and the aluminum salt is aluminum nitrate.

[0016] Preferably, in S1, the molar ratio of magnesium in the magnesium salt, aluminum in the aluminum salt, fumaric acid and urea is (6-13):(5-12):(2.5-5):(15-30).

[0017] Preferably, in S2, after the cerium salt and the copper salt are dissolved in water, 1M sodium hydroxide solution is added, and then stirred at 60°C for 24 hours to obtain a suspension, excess liquid is removed from the suspension, and the remaining solid is washed, and the solid is freeze-dried for 48 hours to obtain Cu 0.1 CeO2 precursor;

[0018] Preferably, in S2, the cerium salt is cerium nitrate, and the copper salt is copper nitrate.

[0019] Preferably, in S2, the molar ratio between copper in the copper salt and cerium in the cerium salt is (0.8-1.2):10.

[0020] More preferably, the molar ratio between the copper in the copper salt and the cerium in the cerium salt is 1:10.

[0021] Preferably, in the S3, Cu 0.1 The mass ratio of CeO2 precursor to three-dimensional hydrangea-shaped hydrotalcite is 0.3-0.4.

[0022] Preferably, in S3, the calcination temperature of the mixture powder is 400-450° C., and the calcination time of the mixture powder is 2-3 hours.

[0023] More preferably, the calcination temperature of the mixture powder is 400° C., and the calcination time of the mixture powder is 2 h.

[0024] The present invention also provides a Cu 0.1 CeO2@LDO photocatalyst, including calcined hydrotalcite and Cu supported on the calcined hydrotalcite 0.1 CeO2 particles; 0.1 The content of the calcined hydrotalcite is 50-80 wt % based on the mass of CeO2@LDO photocatalyst; 0.1 The particle size of CeO2@LDO photocatalyst is 2-5 μm, and the specific surface area is 180-200 m 2 g -1 .

[0025] The present invention also provides Cu prepared by the above preparation method 0.1 CeO2@LDO photocatalyst or the above Cu 0.1 Application of CeO2@LDO photocatalyst in photothermal catalysis of cellulose to produce lactic acid and formic acid.

[0026] Preferably, the cellulose is a cellulose suspension treated with periodate oxidation.

[0027] Preferably, the periodate oxidation treatment method is: ultrasonically dispersing microcrystalline cellulose in deionized water, adding NaIO4, adjusting the pH to 2.0-4.0 with hydrochloric acid, reacting for 2-8 hours, and then adding sodium hydroxide to adjust the pH to 7.0 to obtain a cellulose suspension.

[0028] Preferably, the application method is: Cu 0.1 After CeO2@LDO photocatalyst, sodium hydroxide and cellulose are evenly mixed, the reaction is carried out under a xenon lamp at 25-95°C for 1-6 hours; 0.1The ratio of CeO2@LDO photocatalyst, sodium hydroxide and cellulose is (0.1~50) mg: (0.1~5.0) g: (10~50) mL.

[0029] Therefore, the present invention has the following beneficial effects:

[0030] (1) Cu prepared by the present invention 0.1 The CeO2@LDO photocatalyst not only has the three-dimensional hydrangea-like morphology of hydrotalcite, but also has stronger visible light absorption capacity and large specific surface area, thus having higher photocatalytic activity and good application prospects.

[0031] (2) The present invention utilizes a specific synthesis temperature to control the Cu 0.1 The precursors of CeO2 and LDO single materials are pre-selected for the synthesis of composite materials.

[0032] (3) The special application treatment method provided by the present invention helps to improve the conversion rate of photothermal catalytic cellulose to produce lactic acid and formic acid; this treatment method has the advantages of being green, environmentally friendly, high in yield, and low in energy consumption, and has the potential for industrial production.

[0033] (4) The present invention selectively converts cellulose into lactic acid and formic acid through photothermal catalysis, which can effectively solve the problem of cellulose recycling and provide an effective way to solve the energy crisis. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is the result diagram of the effect of oxidation time on the photothermal catalytic conversion of cellulose to produce lactic acid and formic acid;

[0035] Figure 2 This is the result diagram of the effect of NaOH concentration on the photothermal catalytic conversion of cellulose to produce lactic acid and formic acid;

[0036] Figure 3 This is a graph showing the effect of reaction temperature on the production of lactic acid and formic acid from thermal catalytic cellulose conversion;

[0037] Figure 4 This is the result diagram of the effect of reaction temperature on the photothermal catalytic conversion of cellulose to produce lactic acid and formic acid;

[0038] Figure 5 This is the result diagram of the effect of reaction time on the photothermal catalytic conversion of cellulose to produce lactic acid and formic acid;

[0039] Figure 6 SEM images, a is LDO, b is Cu 0.1 CeO2, c is Cu 0.1 CeO2@LDO, d is the enlarged image of c;

[0040] Figure 7 XRD patterns, a is LDO, b is Cu 0.1 CeO2, c is Cu 0.1 CeO2@LDO;

[0041] Figure 8 It is an XPS graph;

[0042] Figure 9 is the N2 desorption diagram;

[0043] Figure 10 This figure shows the effects of different materials on the photothermal catalytic conversion of cellulose to produce lactic acid and formic acid. DETAILED DESCRIPTION

[0044] The present invention will be further described below with reference to specific embodiments. Those skilled in the art will be able to implement the present invention based on these descriptions. Furthermore, the embodiments of the present invention described below generally represent only a portion of the present invention, rather than all of the embodiments. Therefore, all other embodiments derived by those skilled in the art based on the embodiments of the present invention without inventive effort should fall within the scope of protection of the present invention.

[0045] [Example]

[0046] Example 1

[0047] (1) 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) were dissolved in 60 mL of deionized water by stirring at room temperature. Then, 1.6 g of Mg(NO3)2·6H2O (6.25 mmol) and 1.2 g of Al(NO3)3·9H2O (5.74 mmol) were added to the solution and stirred for 60 min to obtain a mixed solution.

[0048] (2) The mixed solution in (1) was transferred to a 100 mL Teflon-lined stainless steel autoclave and kept at 110°C for 10 h. The resulting suspension was free of excess liquid and the remaining solid was washed. The solid was freeze-dried for 48 h to obtain a three-dimensional hydrangea-shaped hydrotalcite.

[0049] (3) 0.2 g Cu(NO3)2·3H2O (0.83 mmol) and 3.5 g Ce(NO3)3·6H2O (8.06 mmol) were dissolved in 100 mL deionized water, and then 1 M NaOH solution was added as a precipitant. The suspension was vigorously stirred at 60 °C for 24 h to obtain a suspension. The excess liquid was removed from the suspension and the remaining solid was washed. The solid was freeze-dried for 48 h to obtain Cu 0.1 CeO2 precursor.

[0050] (4) Weigh 1.2 g of the three-dimensional hydrangea-shaped hydrotalcite prepared in (2) and add it to 30 mL of deionized water. Ultrasonicate for 60 min, then add 20 mL of anhydrous ethanol and 0.4 g of the Cu prepared in (3). 0.1 CeO2 precursor was stirred vigorously for 1 hour to obtain a suspension, and the remaining solid was washed after removing excess liquid from the suspension. The solid was freeze-dried for 48 hours to obtain Cu 0.1 CeO2@LDO photocatalyst precursor.

[0051] (5) Weigh the Cu in (4) 0.1 2.0 g of CeO2@LDO photocatalyst precursor was placed in an alumina crucible and kept at 400 °C in a tube furnace for 2 h to obtain Cu 0.1 CeO2@LDO photocatalyst.

[0052] Comparative Example 1

[0053] (1) 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) were dissolved in 60 mL of deionized water by stirring at room temperature. Then, 1.6 g of Mg(NO3)2·6H2O (6.25 mmol) and 1.2 g of Al(NO3)3·9H2O (5.74 mmol) were added to the solution and stirred for 60 min to obtain a mixed solution.

[0054] (2) The mixed solution in (1) was transferred to a 100 mL Teflon-lined stainless steel autoclave and kept at 110°C for 10 h. The resulting suspension was free of excess liquid and the remaining solid was washed. The solid was freeze-dried for 48 h to obtain a three-dimensional hydrangea-shaped hydrotalcite. The three-dimensional hydrangea-shaped hydrotalcite was then placed in an alumina crucible and kept at 400°C in a tube furnace for 2 h to obtain a calcined hydrotalcite LDO.

[0055] Comparative Example 2

[0056] (1) 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) were dissolved in 60 mL of deionized water at room temperature with stirring. 1.6 g of Mg(NO₃)₂·6H₂O (6.25 mmol) and 1.2 g of Al(NO₃)₃·9H₂O (5.74 mmol) were then added to the solution and stirred for 60 min to obtain a mixed solution. The mixed solution was then vigorously stirred at 60°C for 24 h to obtain a suspension. The excess liquid was removed from the suspension, and the remaining solid was washed. The solid was then freeze-dried for 48 h to obtain magnesium-aluminum hydrotalcite.

[0057] (2) 0.2 g Cu(NO3)2·3H2O (0.83 mmol) and 3.5 g Ce(NO3)3·6H2O (8.06 mmol) were dissolved in 100 mL deionized water, and then 1 M NaOH solution was added as a precipitant. The suspension was vigorously stirred at 60 °C for 24 h to obtain a suspension. The excess liquid was removed from the suspension and the remaining solid was washed. The solid was freeze-dried for 48 h to obtain Cu 0.1 CeO2 precursor.

[0058] (3) Weigh 1.2 g of the magnesium aluminum hydrotalcite prepared in (1) and add it to 30 mL of deionized water. Ultrasonicate for 60 min, then add 20 mL of anhydrous ethanol and 0.4 g of the Cu prepared in (3). 0.1 CeO2 precursor was stirred vigorously for 1 hour to obtain a suspension, and the remaining solid was washed after removing excess liquid from the suspension. The solid was freeze-dried for 48 hours to obtain Cu 0.1 CeO2@LDO photocatalyst precursor.

[0059] (4) Weigh the Cu in (3) 0.1 2.0 g of CeO2@LDO photocatalyst precursor was placed in an alumina crucible and kept at 400 °C in a tube furnace for 2 h to obtain Cu 0.1 CeO2@LDO photocatalyst.

[0060] Comparative Example 3

[0061] 0.2 g Cu(NO3)2·3H2O (0.83 mmol) and 3.5 g Ce(NO3)3·6H2O (8.06 mmol) were dissolved in 100 mL deionized water, and then 1 M NaOH solution was added as a precipitant. The suspension was vigorously stirred at 60 ° C for 24 h to obtain a suspension. After removing excess liquid from the suspension, the remaining solid was washed and freeze-dried for 48 h to obtain Cu 0.1 CeO2 precursor. Cu 0.1 The CeO2 precursor was placed in an alumina crucible and kept at 400℃ in a tube furnace for 2h to obtain Cu 0.1 CeO2.

[0062] Comparative Example 4

[0063] (1) 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) were dissolved in 60 mL of deionized water by stirring at room temperature. Then, 1.6 g of Mg(NO3)2·6H2O (6.25 mmol) and 1.2 g of Al(NO3)3·9H2O (5.74 mmol) were added to the solution and stirred for 60 min to obtain a mixed solution.

[0064] (2) The mixed solution in (1) was transferred to a 100 mL Teflon-lined stainless steel autoclave and kept at 110°C for 10 h. The resulting suspension was free of excess liquid and the remaining solid was washed. The solid was freeze-dried for 48 h to obtain a three-dimensional hydrangea-shaped hydrotalcite.

[0065] (3) 0.2 g Cu(NO3)2·3H2O (0.83 mmol) and 3.5 g Ce(NO3)3·6H2O (8.06 mmol) were dissolved in 100 mL deionized water at room temperature, and then 1 M NaOH solution was added as a precipitant and stirred for 60 min to obtain a mixed solution. The mixed solution was transferred to a 100 mL Teflon-lined stainless steel autoclave and kept at 110°C for 10 h. The resulting suspension was then washed with the remaining solid after removing excess liquid. The solid was freeze-dried for 48 h to obtain Cu 0.1 CeO2 precursor.

[0066] (4) Weigh 1.2 g of the three-dimensional hydrangea-shaped hydrotalcite prepared in (2) and add it to 30 mL of deionized water. Ultrasonicate for 60 min, then add 20 mL of anhydrous ethanol and 0.4 g of the Cu prepared in (3). 0.1 CeO2 precursor was stirred vigorously for 1 hour to obtain a suspension, and the remaining solid was washed after removing excess liquid from the suspension. The solid was freeze-dried for 48 hours to obtain Cu 0.1 CeO2@LDO photocatalyst precursor.

[0067] (5) Weigh the Cu in (4) 0.1 2.0 g of CeO2@LDO photocatalyst precursor was placed in an alumina crucible and kept at 400 °C in a tube furnace for 2 h to obtain Cu 0.1 CeO2@LDO photocatalyst.

[0068] Comparative Example 5

[0069] This comparative example is basically the same as Example 1, except that: in (3), the amount of Cu(NO3)2·3H2O used is 0.3 g (1.25 mmol), and Cu 0.15 CeO2 precursor, and finally Cu 0.15 CeO2@LDO photocatalyst.

[0070] Comparative Example 6

[0071] This comparative example is basically the same as Example 1, except that: in (3), the amount of Cu(NO3)2·3H2O used is 0.1 g (0.42 mmol), and Cu 0.05 CeO2 precursor, and finally Cu 0.05 CeO2@LDO photocatalyst.

[0072] Comparative Example 7 (Cu 0.1 The mass ratio of CeO2 precursor and three-dimensional hydrangea-shaped hydrotalcite is too low, that is, Cu 0.1 Low CeO2 precursor loading)

[0073] This comparative example is basically the same as Example 1, except that: in (4), the amount of three-dimensional hydrangea-shaped hydrotalcite is 1.2 g, Cu 0.1 The amount of CeO2 precursor used is 0.24g, Cu 0.1 The mass ratio of CeO2 precursor and three-dimensional hydrangea-like hydrotalcite is 0.2.

[0074] Comparative Example 8

[0075] This comparative example is basically the same as Example 1, except that: in (4), the amount of three-dimensional hydrangea-shaped hydrotalcite is 1.2 g, Cu 0.1 The amount of CeO2 precursor used is 0.6g, Cu 0.1 The mass ratio of CeO2 precursor and three-dimensional hydrangea-like hydrotalcite is 0.5.

[0076] Application Example 1

[0077] This part studies the effect of periodate oxidation reaction time

[0078] (1) At 30°C, 0.1 g of microcrystalline cellulose was added to 20 mL of deionized water and ultrasonically dispersed for 2 h. Then, 0.2 g of NaIO4 was added and 0.1 mol·L -1 The pH of the solution was adjusted to 3.0 with hydrochloric acid, and the beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After different oxidation reaction periods (2 h, 3 h, 4 h, 6 h, 8 h, or 10 h), a few drops of 1 M NaOH were added to adjust the solution pH to neutral to obtain a cellulose suspension.

[0079] (2) Take 30 mg of Cu prepared in Example 1 0.1 CeO2@LDO photocatalyst and 1.6 g NaOH were added to the cellulose suspension prepared in step (1).

[0080] (3) The solution from step (2) was added to a 100 mL quartz pressure bottle, sealed, and a magnetic rotor was added. The mixture was stirred in the dark for 30 min.

[0081] (4) After the system in step (3) was stirred evenly, it was subjected to light irradiation reaction at 90° C. for 6 h using a stirring base CEL HPR100T and a photocatalytic reaction system (300 W xenon lamp light source, stirring speed 300 rpm / min).

[0082] (5) The system after the reaction in step (4) is subjected to high performance liquid chromatography to determine the contents of lactic acid and formic acid.

[0083] The results are as follows Figure 1 As shown, it can be seen that the lactic acid and formic acid yields of unpretreated cellulose are low. When the cellulose oxidation time reaches 4 hours, the lactic acid yield reaches the maximum value. If the oxidation time is further extended, the lactic acid yield decreases, and the formic acid yield gradually increases with the oxidation time. The changes in lactic acid and formic acid yields indicate that oxidation treatment is beneficial to the conversion of cellulose to produce lactic acid and formic acid, and the optimal oxidation time is 4 hours.

[0084] Application Example 2

[0085] This part studies the effect of sodium hydroxide concentration in the photocatalytic system

[0086] (1) At 30°C, 0.1 g of microcrystalline cellulose was added to 20 mL of deionized water and ultrasonically dispersed for 2 h. Then, 0.2 g of NaIO4 was added and 0.1 mol·L -1 The pH of the hydrochloric acid solution was adjusted to 3.0, and the beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After 4 h of oxidation, a few drops of 1 M NaOH were added to adjust the pH of the solution to neutral to obtain a cellulose suspension.

[0087] (2) Take 30 mg of Cu prepared in Example 1 0.1 CeO2@LDO photocatalyst and different weights of NaOH (0.4 g, 0.8 g, 1.2 g, 1.6 g, 2.0 g, 2.4 g) were added to the cellulose suspension prepared in step (1).

[0088] (3) The solution from step (2) was added to a 100 mL quartz pressure bottle, sealed, and a magnetic rotor was added. The mixture was stirred in the dark for 30 min.

[0089] (4) After the system in step (3) was stirred evenly, it was subjected to light irradiation reaction at 90° C. for 6 h using a stirring base CEL HPR100T and a photocatalytic reaction system (300 W xenon lamp light source, stirring speed 300 rpm / min).

[0090] (5) The system after the reaction in step (4) is subjected to high performance liquid chromatography to determine the contents of lactic acid and formic acid.

[0091] The results are as follows Figure 2As shown in the figure, when the amount of sodium hydroxide is 1.6g (the sodium hydroxide concentration in the system is 2M), the yield of lactic acid and formic acid reaches the highest. Specifically, increasing the alkali concentration in the reaction system is more conducive to the production of lactic acid and formic acid. When the concentration is increased to 2M, the yield of lactic acid and formic acid reaches the maximum. When the concentration is increased again, the yield of lactic acid and formic acid decreases. This may be because when the alkali concentration is too high, cellulose may be irreversibly converted to cellulose II. Cellulose II has a more stable crystal structure and a higher surface charge density, which is not conducive to the reaction.

[0092] Application Example 3

[0093] This part studies the effect of catalytic temperature in thermal catalytic systems

[0094] (1) At 30°C, 0.1 g of microcrystalline cellulose was added to 20 mL of deionized water and ultrasonically dispersed for 2 h. Then, 0.2 g of NaIO4 was added and 0.1 mol·L -1 The pH of the hydrochloric acid solution was adjusted to 3.0, and the beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After 4 h of oxidation, a few drops of 1 M NaOH were added to adjust the pH of the solution to neutral to obtain a cellulose suspension.

[0095] (2) Take 30 mg of Cu prepared in Example 1 0.1 CeO2@LDO photocatalyst and 1.6 g NaOH were added to the cellulose suspension prepared in step (1).

[0096] (3) The solution from step (2) was added to a 100 mL quartz pressure bottle, sealed, and a magnetic rotor was added. The mixture was stirred in the dark for 30 min.

[0097] (4) After the system of step (3) was stirred evenly, the reaction was carried out for 6 h in the absence of light and at different reaction temperatures (25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 95°C) using a stirring base CEL HPR100T and a photocatalytic reaction system (300W xenon lamp light source, light not turned on; stirring speed 300 rpm / min).

[0098] (5) The system after the reaction in step (4) is subjected to high performance liquid chromatography to determine the contents of lactic acid and formic acid.

[0099] Figure 3 Shows Cu 0.1 The influence of the CeO2@LDO catalyst on the results of the thermal catalytic process within the temperature range of 30-90°C was observed. No product was observed below 40°C, and the thermal catalytic process started at approximately 40°C. As the temperature increased, the yields of both products showed a slow upward trend until reaching a maximum at 90°C. Therefore, the optimal reaction temperature for the thermal catalytic process was determined to be 90°C.

[0100] Application Example 4

[0101] This part studies the effect of catalytic temperature on the photothermal catalytic system.

[0102] (1) At 30°C, 0.1 g of microcrystalline cellulose was added to 20 mL of deionized water and ultrasonically dispersed for 2 h. Then, 0.2 g of NaIO4 was added and 0.1 mol·L -1 The pH of the solution was adjusted to 3.0 with hydrochloric acid, and the beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After 4 h of oxidation, a few drops of 1 M NaOH were added to adjust the pH of the solution to neutral to obtain a cellulose suspension.

[0103] (2) Take 30 mg of Cu prepared in Example 1 0.1 CeO2@LDO photocatalyst and 1.6 g NaOH were added to the cellulose suspension prepared in step (1).

[0104] (3) The solution from step (2) was added to a 100 mL quartz pressure bottle, sealed, and a magnetic rotor was added. The mixture was stirred in the dark for 30 min.

[0105] (4) After the system in step (3) was stirred evenly, the reaction was carried out for 6 h at different reaction temperatures (25°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, 90°C, 95°C) using a stirring base CEL HPR100T and a photocatalytic reaction system (300W xenon lamp light source, stirring speed 300 rpm / min).

[0106] (5) The system after the reaction in step (4) is subjected to high performance liquid chromatography to determine the contents of lactic acid and formic acid.

[0107] based on Figure 3 Experimental results from the moderately heated catalysis indicate that cellulose conversion at 30°C is primarily driven by photocatalysis. At temperatures above 40°C, the synergistic effects of photocatalysis and thermocatalysis significantly increase the yields of lactic acid and formic acid. When the temperature rises to 90°C, the yields of lactic acid and formic acid reach their maximum values, indicating that the optimal reaction temperature for the photothermal catalytic process is 90°C.

[0108] Application Example 5

[0109] This part studies the effect of catalytic time on the photocatalytic system

[0110] (1) At 30°C, 0.1 g of microcrystalline cellulose was added to 20 mL of deionized water and ultrasonically dispersed for 2 h. Then, 0.2 g of NaIO4 was added and 0.1 mol·L -1The pH of the solution was adjusted to 3.0 with hydrochloric acid, and the beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After 4 h of oxidation, a few drops of 1 M NaOH were added to adjust the pH of the solution to neutral to obtain a cellulose suspension.

[0111] (2) Take 30 mg of Cu prepared in Example 1 0.1 CeO2@LDO photocatalyst and 1.6 g NaOH were added to the cellulose suspension prepared in step (1).

[0112] (3) The solution from step (2) was added to a 100 mL quartz pressure bottle, sealed, and a magnetic rotor was added. The mixture was stirred in the dark for 30 min.

[0113] (4) After the system in step (3) was stirred evenly, the reaction was continued at 90° C. for different times (2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h) using a stirring base CEL HPR100T and a photocatalytic reaction system (300 W xenon lamp light source, stirring speed 300 rpm / min).

[0114] (5) The system after the reaction in step (4) is subjected to high performance liquid chromatography to determine the contents of lactic acid and formic acid.

[0115] The results are as follows Figure 5 As shown in the figure, the yields of lactic acid and formic acid reached their highest values ​​when the reaction time was 6 hours. Specifically, as the reaction time increased from 2 hours to 6 hours, the lactic acid and formic acid yields increased rapidly. After 6 hours, the lactic acid yield decreased slightly. This may be due to the excessively long reaction time causing the produced lactic acid to undergo side reactions and be partially decomposed. Therefore, the optimal reaction time is 6 hours.

[0116]

Performance test

[0117] 1. Morphology and structure

[0118] Example 1Cu 0.1 CeO2@LDO photocatalyst, comparative example 1 LDO, comparative example 3 Cu 0.1 CeO2 was tested by scanning electron microscopy, and the results are as follows Figure 6 shown. Figure 6 a shows the three-dimensional hydrangea-like structure of LDO, which is characterized by an ordered hierarchical porous spherical structure. Figure 6 b shows the prepared Cu 0.1 Scanning electron microscope image of CeO2 nanoparticles, combined with Figure 6 c, 6d Cu 0.1 The scanning electron microscope spectrum of CeO2@LDO photocatalyst shows that Cu 0.1 CeO2@LDO photocatalyst has a typical layered structure of hydrotalcite and a large number of pores on the surface of hydrotalcite, and Cu0.1 CeO2 nanoparticles are evenly distributed on the surface of hydrotalcite. 0.1 The CeO2@LDO photocatalyst still retains the three-dimensional hydrangea structure of hydrotalcite, which helps to improve the Cu 0.1 Dispersion and stability of CeO2 nanoparticles on the catalyst surface.

[0119] To further evaluate the synthesized Cu 0.1 The specific structure of CeO2@LDO photocatalyst 0.1 CeO2@LDO photocatalyst, LDO, Cu 0.1 CeO2 was characterized by XRD, and the results are as follows Figure 7 As shown; for Cu 0.1 The CeO2@LDO photocatalyst was characterized by XPS. Figure 8 shown.

[0120] observe Figure 7 It can be seen from the figure that Cu 0.1 CeO2@LDO photocatalyst has the crystallization peak of LDO, and the spectrum of the composite material is similar to that of Cu 0.1 CeO2 spectra are very similar, which indicates that Cu 0.1 CeO2 was successfully loaded on the surface of LDO, and Cu 0.1 CeO2@LDO photocatalyst was successfully synthesized. Figure 8 Cu is shown in 0.1 In CeO2@LDO photocatalyst, Ce, Cu, O, Mg and Al elements coexist, proving that Cu is successfully doped into CeO2 to form Cu 0.1 CeO2.

[0121] 2. Aperture

[0122] Figure 9 For LDO, Cu 0.1 CeO2 and Cu 0.1 The N2 adsorption-desorption isotherms of CeO2@LDO photocatalysts show that all three materials show a type IV isotherm pattern, indicating that Cu 0.1 CeO2@LDO photocatalyst is a mesoporous material. LDO, Cu 0.1 CeO2 and Cu 0.1 The specific surface areas of CeO2@LDO are 105.940m 2 g -1 、78.368m 2 g -1 and 190.134m 2 g -1 .

[0123] Analysis of the above results shows that: Cu 0.1 CeO2@LDO utilizes the large specific surface area structure of LDO matrix to composite LDO and Cu 0.1 CeO2 is not affected by the small specific surface area Cu 0.1 The effect of CeO2, on the contrary, shows a larger specific surface area than LDO. The particularity of this result not only proves that Cu 0.1 CeO2@LDO photocatalyst generates more active sites with its large surface area, which greatly improves the catalytic conversion efficiency. 0.1 The CeO2@LDO photocatalyst exhibits a large surface area property that is superior to that of any single material.

[0124] 3. Application Performance

[0125] In Application Examples 1 to 5, the application conditions were screened and the optimal parameters were determined. In this section, the performance of the materials obtained in Example 1 and Comparative Examples 1 to 8 was tested according to the following test methods based on the determined parameter results, and the effects of material changes and reaction condition changes on the application performance were compared. The results are shown in the figure below. Figure 10 shown.

[0126] This part of the determination method:

[0127] (1) At 30°C, 0.1 g of microcrystalline cellulose was added to 20 mL of deionized water and ultrasonically dispersed for 2 h. Then, 0.2 g of NaIO4 was added and 0.1 mol·L -1 The pH of the solution was adjusted to 3.0 with hydrochloric acid, and the beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After 4 h of oxidation, a few drops of 1 M NaOH were added to adjust the pH of the solution to neutral to obtain a cellulose suspension.

[0128] (2) 30 mg of catalyst material and 1.6 g of NaOH were added to the cellulose suspension prepared in step (1).

[0129] (3) The solution from step (2) was added to a 100 mL quartz pressure bottle, sealed, and a magnetic rotor was added. The mixture was stirred in the dark for 30 min.

[0130] (4) After the system in step (3) was stirred evenly, the mixture was reacted at 90° C. for 6 h using a stirring base CEL HPR100T and a photocatalytic reaction system (300 W xenon lamp light source, stirring speed 300 rpm / min).

[0131] (5) The system after the reaction in step (4) is subjected to high performance liquid chromatography to determine the contents of lactic acid and formic acid.

[0132] Depend on Figure 10 a It can be seen that the yields of lactic acid and formic acid under the catalysis of a single material are average. 0.1CeO2 can be evenly distributed on the three-dimensional embroidery-like surface of LDO. The rich pores and large specific surface area of ​​LDO increase the active sites of the catalyst and improve the catalyst performance, thus significantly improving the yield of lactic acid and formic acid. Figure 10 From the data in b, we can see that the synthesis temperature of a single material has a great influence on the yield of lactic acid and formic acid. This is because at room temperature, it is not conducive to the formation of a three-dimensional hydrangea-like morphology of LDO. At higher temperatures, the Cu 0.1 The photothermal catalytic performance of CeO2 is also poor, and compared with LDO, Cu 0.1 CeO2 as a semiconductor material has a greater impact on the composite material. From the comparison of the results of Example 1, Comparative Example 5, and Comparative Example 6, it can be seen that when the Cu doping amount is too high or too low, the photothermal catalytic performance of the composite material is inhibited. The doping effect is best when the molar ratio of copper to cerium is 1 / 10. By comparing the results of Example 1, Comparative Example 7, and Comparative Example 8, it can be seen that when the amount of LDO is too much, the Cu loaded 0.1 The quality of CeO2 will be insufficient, which will lead to a decrease in the proportion of semiconductor materials in the composite material, thereby affecting the photothermal catalytic performance. 0.1 When the amount of CeO2 is too much, it cannot be evenly dispersed on the surface of LDO and easily forms large aggregates, which is not conducive to the catalytic conversion of the composite material.

Claims

1. A Cu 0.1 The preparation method of CeO2@LDO photocatalyst is characterized in that: include: S1. Magnesium salt, aluminum salt, fumaric acid, and urea were dissolved in water, stirred, and then transferred to a high-pressure hydrothermal reactor for hydrothermal reaction to obtain a three-dimensional hydrangea-shaped hydrotalcite; S2. After dissolving cerium salt, copper salt and sodium hydroxide in water, stir at 60-80°C for 18-24h to obtain Cu 0.1 CeO2 precursor; S3. Disperse the three-dimensional hydrangea-shaped hydrotalcite obtained in S1 in water, add anhydrous ethanol and the Cu obtained in S2 0.1 CeO2 precursor, stirred and mixed, and then dried to obtain a mixture powder, and the mixture powder was calcined to obtain Cu 0.1 CeO2@LDO photocatalyst.

2. The preparation method according to claim 1, wherein In S1, the temperature of the hydrothermal reaction is 110-120° C., and the time of the hydrothermal reaction is 6-12 hours.

3. The preparation method according to claim 1 or 2, wherein In the S1, the molar ratio of magnesium in the magnesium salt, aluminum in the aluminum salt, fumaric acid and urea is (6-13): (5-12): (2.5-5): (15-30).

4. The preparation method according to claim 1, wherein In the S2, the molar ratio between copper in the copper salt and cerium in the cerium salt is (0.8-1.2):

10.

5. The preparation method according to claim 1, wherein In the S3, Cu 0.1 The mass ratio of CeO2 precursor to three-dimensional hydrangea-shaped hydrotalcite is 0.3-0.

4.

6. The preparation method according to claim 1, wherein In the step S3, the calcination temperature of the mixture powder is 400-450° C., and the calcination time of the mixture powder is 2-3 hours.

7. Cu obtained by the preparation method according to any one of claims 1 to 6 0.1 CeO2@LDO photocatalyst, characterized in that Comprising calcined hydrotalcite and Cu loaded on calcined hydrotalcite 0.1 CeO2 particles; 0.1 The content of the calcined hydrotalcite is 50-80 wt % based on the mass of CeO2@LDO photocatalyst; 0.1 The particle size of CeO2@LDO photocatalyst is 2-5 μm, and the specific surface area is 180-200 m 2 g -1 .

8. Cu obtained by the preparation method according to any one of claims 1 to 6 0.1 CeO2@LDO photocatalyst or Cu as claimed in claim 7 0.1 The application of CeO2@LDO photocatalyst in photothermal catalysis of cellulose to produce lactic acid and formic acid is characterized by: The cellulose is a cellulose suspension treated with periodate oxidation.

9. The use according to claim 8, characterized in that The cellulose is a cellulose suspension treated with periodate oxidation. The periodate oxidation treatment comprises the following steps: ultrasonically dispersing microcrystalline cellulose in deionized water, adding NaIO4, adjusting the pH to 2.0-4.0 with hydrochloric acid, reacting for 2-8 hours, and then adding sodium hydroxide to adjust the pH to 7.0 to obtain a cellulose suspension.

10. The use according to claim 8 or 9, characterized in that The application method is: Cu 0.1 After CeO2@LDO photocatalyst, sodium hydroxide and cellulose are evenly mixed, the reaction is carried out under a xenon lamp at 25-95°C for 1-6 hours; 0.1 The ratio of CeO2@LDO photocatalyst, sodium hydroxide and cellulose is (0.1~50) mg: (0.1~5.0) g: (10~50) mL.

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