Cu0.1 CeO2-coated LDO photocatalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of photo-thermal catalysis, in particular to a Cu0. 1CeO2-coated LDO photocatalyst as well as a preparation method and application thereof. In order to solve the problems that an existing catalytic system is complex, low in conversion rate and the like, the Cu0. 1CeO2-coated LDO photocatalyst is prepared through a hydrothermal and ethanol impregnation method, and cellulose is selectively converted into lactic acid and formic acid through a photo-thermal catalytic technology. The prepared Cu0. 1CeO2-coated LDO photocatalyst has good chemical stability and photocatalytic performance, can achieve high conversion rate and product selectivity, and compared with traditional thermocatalysis and enzyme catalysis, the method has the advantages of being environmentally friendly, simple, convenient and efficient, and has good application prospects.

Description

Technical Field

[0001] The present invention relates to the technical field of photothermal catalysis, and particularly relates to a Cu 0.1 CeO 2 @LDO photocatalyst and its preparation method and application. Background Art

[0002] With the increasingly serious problems of global ecological environmental pollution and energy shortage, people have begun to seek more environmentally friendly and sustainable energy. As the most abundant organic polymer on the earth, cellulose is widely present in biomass resources and has good biodegradability and regeneration ability. Converting cellulose into high-value-added chemicals, especially lactic acid and formic acid, can provide a sustainable raw material source for the energy and chemical industries. Among them, lactic acid is not only an important bio-based chemical and is widely used in fields such as food, medicine, and biomaterials, while formic acid has broad application prospects in the agricultural and chemical industries due to its good chemical properties and environmental friendliness.

[0003] The currently 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, photothermal catalysis, as an emerging conversion technology, can effectively convert cellulose under mild temperature and environmental conditions by exciting the catalyst with light energy. This process not only improves the selectivity of the reaction but also significantly reduces energy consumption and costs.

[0004] Therefore, developing highly efficient and selective photothermal catalysts and optimizing cellulose conversion conditions have important scientific significance and economic value. Summary of the Invention

[0005] The present invention provides a Cu 0.1 CeO 2 @LDO photocatalyst and its preparation method and application. In view of the problems of the existing complex catalytic system and low conversion rate, etc., the Cu 0.1 CeO 2 @LDO photocatalyst is prepared by a hydrothermal and ethanol impregnation method, and cellulose is selectively converted into lactic acid and formic acid through photothermal catalysis technology. The Cu 0.1 CeO 2 @LDO photocatalyst prepared by the present invention has good chemical stability and photocatalytic performance, can achieve a high conversion rate and product selectivity. Compared with traditional thermal catalysis and enzymatic catalysis, this method has the advantages of being green, simple, and efficient, and has good application prospects.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] The present invention provides a Cu0.1 CeO 2 Preparation method of CeO@LDO photocatalyst, comprising:

[0008] S1. Dissolve magnesium salt, aluminum salt, fumaric acid and urea in water, stir and mix, and then transfer to a high-pressure hydrothermal reactor for hydrothermal reaction to obtain three-dimensional hydrangea-like hydrotalcite;

[0009] S2. After dissolving cerium salt, copper salt and sodium hydroxide in water, stir at 60-80 °C for 18-24 h to obtain Cu 0.1 CeO 2 precursor;

[0010] S3. Disperse the three-dimensional hydrangea-like hydrotalcite obtained in S1 in water, add absolute ethanol and the Cu 0.1 CeO 2 precursor obtained in S2, stir and mix and then perform drying treatment to obtain a mixture powder, and calcine the mixture powder to obtain Cu 0.1 CeO 2 @LDO photocatalyst.

[0011] In this application, composite three-dimensional hydrangea-like hydrotalcite and Cu 0.1 CeO 2 precursor are calcined to obtain Cu 0.1 CeO 2 @LDO. By virtue of the large surface area characteristics of the composite Cu 0.1 CeO 2 @LDO, more active sites are provided, and the efficiency of photocatalytic conversion of cellulose to lactic acid and formic acid is improved. Among them, the acquisition schemes of three-dimensional hydrangea-like hydrotalcite and Cu 0.1 CeO 2 precursor are screened at specific temperatures to ensure the characteristics of the composite material.

[0012] Preferably, after the hydrothermal reaction in S1, freeze-dry for 48 h to obtain three-dimensional hydrangea-like 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 h.

[0014] Further 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 the step S2, after the cerium salt and the copper salt are dissolved in water, 1 M sodium hydroxide solution is added, and then the mixture is stirred at 60 °C for 24 h to obtain a suspension. After removing the excess liquid from the suspension, the remaining solid is washed, and the solid is freeze-dried for 48 h to obtain Cu 0.1 CeO 2 precursor;

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

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

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

[0021] Preferably, in the step S3, the mass ratio of the Cu 0.1 CeO 2 precursor to the three-dimensional hydrangea-like hydrotalcite is 0.3 - 0.4.

[0022] Preferably, 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 h.

[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 CeO 2 @LDO photocatalyst, comprising calcined hydrotalcite and Cu 0.1 CeO 2 particles supported on the calcined hydrotalcite; based on the mass of the Cu 0.1 CeO 2 @LDO photocatalyst, the content of the calcined hydrotalcite is 50 - 80 wt%; the particle size of the Cu 0.1 CeO 2 @LDO photocatalyst is 2 - 5 μm, and the specific surface area is 180 - 200 m 2 g -1 .

[0025] The present invention also provides the Cu 0.1 CeO 2 @LDO photocatalyst prepared by the above preparation method or the application of the above Cu 0.1 CeO 2 @LDO photocatalyst in the photothermal catalytic production of lactic acid and formic acid from cellulose.

[0026] Preferably, the cellulose is a suspension of cellulose after periodate oxidation treatment.

[0027] Preferably, the periodate oxidation treatment method is as follows: microcrystalline cellulose is ultrasonically dispersed in deionized water, and NaIO 4 is added, the pH is adjusted to 2.0 - 4.0 with hydrochloric acid, after reacting for 2 - 8 h, sodium hydroxide is added to adjust the pH to 7.0 to obtain a cellulose suspension.

[0028] Preferably, the application method is as follows: after the Cu 0.1 CeO 2 @LDO photocatalyst, sodium hydroxide, and cellulose are mixed evenly, the reaction is carried out at 25 - 95 °C for 1 - 6 h under a xenon lamp; the ratio of the Cu 0.1 CeO 2 @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) The Cu 0.1 CeO 2 @LDO photocatalyst prepared by the present invention not only has the three-dimensional hydrangea-like morphology of hydrotalcite, but also has stronger visible light absorption ability and a large specific surface area, thus having higher photocatalytic activity and good application prospects.

[0031] (2) The present invention uses specific synthesis temperatures to separately control the precursors of Cu 0.1 CeO 2 and LDO single materials, which makes a pre-selection treatment 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 photocatalytic conversion of cellulose to produce lactic acid and formic acid; this treatment method has the advantages of being green, environmentally friendly, high yield, and low energy consumption, and has the potential for industrial production.

[0033] (4) The present invention effectively solves the problem of cellulose recycling by photocatalytic selective conversion of cellulose to produce lactic acid and formic acid, and provides an effective way to solve the energy crisis problem. Description of the Drawings

[0034] Figure 1 It is a graph showing the influence of oxidation time on the photocatalytic conversion of cellulose to produce lactic acid and formic acid;

[0035] Figure 2 It is a graph showing the influence of NaOH concentration on the photocatalytic conversion of cellulose to produce lactic acid and formic acid;

[0036] Figure 3 Figure showing the influence of reaction temperature on the production of lactic acid and formic acid by thermal catalytic conversion of cellulose

[0037] Figure 4 Figure showing the influence of reaction temperature on the production of lactic acid and formic acid by photocatalytic conversion of cellulose

[0038] Figure 5 Figure showing the influence of reaction time on the production of lactic acid and formic acid by photocatalytic conversion of cellulose

[0039] Figure 6 SEM image, a is LDO, b is Cu 0.1 CeO 2 , c is Cu 0.1 CeO 2 @LDO, d is the enlarged image of c

[0040] Figure 7 XRD pattern, a is LDO, b is Cu 0.1 CeO 2 , c is Cu 0.1 CeO 2 @LDO;

[0041] Figure 8 XPS spectrum

[0042] Figure 9 For N 2 desorption diagram

[0043] Figure 10 Figure showing the influence of different materials on the production of lactic acid and formic acid by photocatalytic conversion of cellulose Detailed implementation methods

[0044] The present invention will be further described below in conjunction with specific embodiments. Those of ordinary skill in the art will be able to implement the present invention based on these descriptions. In addition, the embodiments of the present invention involved in the following description are usually only a part of the embodiments of the present invention, rather than all of the embodiments. Therefore, all other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention

[0045]

Embodiment

[0046] Embodiment 1

[0047] (1) At room temperature, 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, and then 1.6 g of Mg(NO 3 )2 ·6H 2 O (6.25 mmol) and 1.2 g of Al(NO 3 ) 3 ·9H 2 O (5.74 mmol) and stir for 60 min to obtain a mixed solution.

[0048] (2) Transfer the mixed solution in (1) to a 100 mL Teflon-lined stainless steel autoclave, keep it at 110 °C for 10 h. After removing the excess liquid from the obtained suspension, wash the remaining solid. After freeze-drying the solid for 48 h, a three-dimensional hydrangea-like hydrotalcite is obtained.

[0049] (3) Dissolve 0.2 g of Cu(NO 3 ) 2 ·3H 2 O (0.83 mmol) and 3.5 g of Ce(NO 3 ) 3 ·6H 2 O (8.06 mmol) in 100 mL of deionized water. Subsequently, add 1 M NaOH solution as a precipitant and stir vigorously at 60 °C for 24 h to obtain a suspension. After removing the excess liquid from the suspension, wash the remaining solid. After freeze-drying the solid for 48 h, a Cu 0.1 CeO 2 precursor is obtained.

[0050] (4) Weigh 1.2 g of the three-dimensional hydrangea-like hydrotalcite prepared in (2) and add it to 30 mL of deionized water. Sonicate for 60 min, then add 20 mL of absolute ethanol and 0.4 g of the Cu 0.1 CeO 2 precursor prepared in (3). Stir vigorously for 1 h to obtain a suspension. After removing the excess liquid from the suspension, wash the remaining solid. After freeze-drying the solid for 48 h, a Cu 0.1 CeO 2 @LDO photocatalyst precursor is obtained.

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

[0052] Comparative Example 1

[0053] (1) At room temperature, dissolve 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) in 60 mL of deionized water by stirring. Then add 1.6 g of Mg(NO3 ) 2 ·6H 2 O (6.25 mmol) and 1.2 g Al(NO 3 ) 3 ·9H 2 O (5.74 mmol) and stir for 60 min to obtain a mixed solution.

[0054] (2) Transfer the mixed solution in (1) to a 100 mL Teflon-lined stainless steel autoclave, keep it at 110 °C for 10 h. After removing the excess liquid from the obtained suspension, wash the remaining solid. After freeze-drying the solid for 48 h, a three-dimensional hydrangea-like hydrotalcite is obtained. Subsequently, put the three-dimensional hydrangea-like hydrotalcite into an alumina crucible and keep it in a tubular furnace at 400 °C for 2 h to obtain the calcined hydrotalcite LDO.

[0055] Comparative Example 2

[0056] (1) At room temperature, dissolve 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) in 60 mL of deionized water by stirring. Then add 1.6 g of Mg(NO 3 ) 2 ·6H 2 O (6.25 mmol) and 1.2 g of Al(NO 3 ) 3 ·9H 2 O (5.74 mmol) and stir for 60 min to obtain a mixed solution. Subsequently, stir the mixed solution vigorously at 60 °C for 24 h to obtain a suspension. After removing the excess liquid from the suspension, wash the remaining solid. After freeze-drying the solid for 48 h, a magnesium-aluminum hydrotalcite is obtained.

[0057] (2) Dissolve 0.2 g of Cu(NO 3 ) 2 ·3H 2 O (0.83 mmol) and 3.5 g of Ce(NO 3 ) 3 ·6H 2 O (8.06 mmol) in 100 mL of deionized water. Subsequently, add 1 M NaOH solution as a precipitating agent and stir vigorously at 60 °C for 24 h to obtain a suspension. After removing the excess liquid from the suspension, wash the remaining solid. After freeze-drying the solid for 48 h, a Cu 0.1 CeO 2 precursor is obtained.

[0058] (3) Weigh 1.2 g of the magnesium-aluminum hydrotalcite prepared in (1) and add it to 30 mL of deionized water, sonicate for 60 min, then add 20 mL of absolute ethanol and 0.4 g of Cu 0.1 CeO2 The precursor was vigorously stirred for 1 h to obtain a suspension. After removing the excess liquid from the suspension, the remaining solid was washed, and the solid was freeze-dried for 48 h to obtain Cu. 0.1 CeO 2 @LDO photocatalyst precursor.

[0059] (4) Weigh 2.0 g of the Cu 0.1 CeO 2 @LDO photocatalyst precursor and put it into an alumina crucible. Keep it at 400 °C in a tube furnace for 2 h to obtain Cu 0.1 CeO 2 @LDO photocatalyst.

[0060] Comparative Example 3

[0061] Dissolve 0.2 g of Cu(NO 3 ) 2 ·3H 2 O (0.83 mmol) and 3.5 g of Ce(NO 3 ) 3 ·6H 2 O (8.06 mmol) in 100 mL of deionized water. Subsequently, add 1 M NaOH solution as a precipitant and vigorously stir at 60 °C for 24 h to obtain a suspension. After removing the excess liquid from the suspension, the remaining solid was washed, and the solid was freeze-dried for 48 h to obtain Cu 0.1 CeO 2 precursor. Cu 0.1 CeO 2 The precursor was put into an alumina crucible and kept at 400 °C in a tube furnace for 2 h to obtain Cu 0.1 CeO 2 .

[0062] Comparative Example 4

[0063] (1) At room temperature, dissolve 0.3 g of fumaric acid (2.59 mmol) and 1.2 g of urea (20.00 mmol) in 60 mL of deionized water by stirring, and then add 1.6 g of Mg(NO 3 ) 2 ·6H 2 O (6.25 mmol) and 1.2 g of Al(NO 3 ) 3 ·9H 2 O (5.74 mmol) to the solution and stir for 60 min to obtain a mixed solution.

[0064] (2) Transfer the mixed solution in (1) to a 100 mL Teflon-lined stainless steel autoclave, keep it at 110 °C for 10 h. After removing the excess liquid from the obtained suspension, wash the remaining solid, and freeze-dry the solid for 48 h to obtain three-dimensional hydrangea-like hydrotalcite.

[0065] (3) Dissolve 0.2 g of Cu(NO 3 ) 2 ·3H 2 O (0.83 mmol) and 3.5 g of Ce(NO 3 ) 3 ·6H 2 O (8.06 mmol) in 100 mL of deionized water. Subsequently, add 1 M NaOH solution as a precipitant and stir for 60 min to obtain a mixed solution. Transfer the mixed solution to a 100 mL Teflon-lined stainless steel autoclave, keep it at 110 °C for 10 h. After removing the excess liquid from the obtained suspension, wash the remaining solid, and freeze-dry the solid for 48 h to obtain a Cu 0.1 CeO 2 precursor.

[0066] (4) Weigh 1.2 g of the three-dimensional hydrangea-like hydrotalcite prepared in (2), add it to 30 mL of deionized water, sonicate for 60 min, then add 20 mL of absolute ethanol and 0.4 g of the Cu 0.1 CeO 2 precursor prepared in (3), stir vigorously for 1 h to obtain a suspension. After removing the excess liquid from the suspension, wash the remaining solid, and freeze-dry the solid for 48 h to obtain a Cu 0.1 CeO 2 @LDO photocatalyst precursor.

[0067] (5) Weigh 2.0 g of the Cu 0.1 CeO 2 @LDO photocatalyst precursor in (4) and put it into an alumina crucible, keep it at 400 °C in a tube furnace for 2 h to obtain a Cu 0.1 CeO 2 @LDO photocatalyst.

[0068] Comparative Example 5

[0069] This comparative example is basically the same as Example 1, and the difference lies in that: in (3), the dosage of Cu(NO 3 ) 2 ·3H 2 O is 0.3 g (1.25 mmol) to obtain a Cu 0.15 CeO 2 precursor, and finally obtain a Cu 0.15 CeO 2 @LDO photocatalyst.

[0070] Comparative Example 6

[0071] This comparative example is basically the same as Example 1, and the difference lies in that: in (3), the dosage of Cu(NO 3 ) 2 ·3H 2 O is 0.1 g (0.42 mmol) to obtain a Cu 0.05 CeO 2 precursor, and finally obtain a Cu 0.05 CeO 2 @LDO photocatalyst.

[0072] Comparative Example 7 (the mass ratio of the Cu 0.1 CeO 2 precursor to the three-dimensional hydrangea-like hydrotalcite is too low, that is, the loading amount of the Cu 0.1 CeO 2 precursor is low)

[0073] This comparative example is basically the same as Example 1, and the difference lies in that: in (4), the dosage of the three-dimensional hydrangea-like hydrotalcite is 1.2 g, and the dosage of the Cu 0.1 CeO 2 precursor is 0.24 g, and the mass ratio of the Cu 0.1 CeO 2 precursor to the three-dimensional hydrangea-like hydrotalcite is 0.2.

[0074] Comparative Example 8

[0075] This comparative example is basically the same as Example 1, and the difference lies in that: in (4), the dosage of the three-dimensional hydrangea-like hydrotalcite is 1.2 g, and the dosage of the Cu 0.1 CeO 2 precursor is 0.6 g, and the mass ratio of the Cu 0.1 CeO 2 precursor to the three-dimensional hydrangea-like hydrotalcite is 0.5.

[0076] Application Example 1

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

[0078] (1) At 30 °C, add 0.1 g of microcrystalline cellulose to 20 mL of deionized water and ultrasonically disperse for 2 h, then add 0.2 g of NaIO 4 and adjust the pH to 3.0 with 0.1 mol·L -1 hydrochloric acid solution. Cover the beaker with aluminum foil to prevent the photocatalytic decomposition of periodate. After oxidizing for different periods of time (2 h, 3 h, 4 h, 6 h, 8 h or 10 h), add a few drops of 1 M NaOH to adjust the pH of the solution to neutral to obtain a cellulose suspension.

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

[0080] (3) Add the solution in step (2) to a 100 mL quartz pressure-resistant bottle, seal it and add a magnetic rotor, and stir for 30 min under dark conditions.

[0081] (4) After stirring the system in step (3) evenly, carry out a photocatalytic reaction under illumination at 90 °C for 6 h through a stirring base CEL HPR100T and a photocatalytic reaction system (300 W xenon lamp light source, stirring speed 300 rpm / min).

[0082] (5) Determine the contents of lactic acid and formic acid in the system after the reaction in step (4) by a high performance liquid chromatograph.

[0083] The results are as Figure 1 shown. It can be seen that the yields of lactic acid and formic acid of the untreated cellulose are both low. When the cellulose oxidation time reaches 4 h, the lactic acid yield reaches the maximum value. Continuing to extend the oxidation time, the lactic acid yield decreases somewhat, and the formic acid yield gradually increases with the oxidation time. The changes in the yields of lactic acid and formic acid indicate that the oxidation treatment is beneficial to the conversion of cellulose to produce lactic acid and formic acid, and the optimal oxidation time is 4 h.

[0084] Application Example 2

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

[0086] (1) At 30 °C, add 0.1 g of microcrystalline cellulose to 20 mL of deionized water, disperse it by ultrasonic wave for 2 h, then add 0.2 g of NaIO 4 and adjust the pH to 3.0 with 0.1 mol·L -1 hydrochloric acid solution, and cover the beaker with aluminum foil to prevent the photocatalytic decomposition of periodate. After the oxidation reaction for 4 h, add a few drops of 1 M NaOH to adjust the pH of the solution to neutral to obtain a cellulose suspension.

[0087] (2) Take 30 mg of the Cu prepared in Example 1 0.1 CeO 2 @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), and add them to the cellulose suspension prepared in step (1).

[0088] (3) Add the solution in step (2) to a 100 mL quartz pressure-resistant bottle, seal it and add a magnetic rotor, and stir for 30 min under dark conditions.

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

[0090] (5) Determine the contents of lactic acid and formic acid in the system after the reaction in step (4) by using a high performance liquid chromatograph.

[0091] The results are as Figure 2 shown. When the dosage of sodium hydroxide is 1.6 g (the concentration of sodium hydroxide in the system is 2 M), the yields of lactic acid and formic acid reach the highest. Specifically, the increase in the alkali concentration in the reaction system is more conducive to the production of lactic acid and formic acid. When the concentration increases to 2 M, the yields of lactic acid and formic acid reach the maximum. When the concentration increases again, the yields of lactic acid and formic acid decrease. This may be because when the alkali concentration is too high, cellulose may be irreversibly converted into cellulose II form. Cellulose II has a more stable crystal structure and a higher surface charge density, which is not conducive to the progress of the reaction.

[0092] Application Example 3

[0093] This part studies the influence of the catalytic temperature in the thermal catalytic system

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

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

[0096] (3) Add the solution in step (2) to a 100 mL quartz pressure-resistant bottle, seal it and add a magnetic rotor, and stir it in the dark for 30 min.

[0097] (4) After the system in step (3) is stirred evenly, react it 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) without light through a stirring base CEL HPR100T and a photocatalytic reaction system (300 W xenon lamp light source, the lamp is not turned on; stirring speed 300 rpm / min).

[0098] (5) Determine the contents of lactic acid and formic acid in the system after the reaction in step (4) by high performance liquid chromatography.

[0099] Figure 3 shows Cu 0.1 CeO 2 The influence of the Cu

[0100] Application Example 4

[0101] This part studies the influence of the catalytic temperature in the photothermal catalytic system

[0102] (1) At 30 °C, add 0.1 g of microcrystalline cellulose to 20 mL of deionized water and ultrasonically disperse for 2 h, then add 0.2 g of NaIO 4 and adjust the pH to 3.0 with 0.1 mol·L -1 hydrochloric acid solution. Cover the beaker with aluminum foil to prevent the photocatalytic decomposition of periodate. After the oxidation reaction for 4 h, add a few drops of 1 M NaOH to adjust the pH of the solution to neutral to obtain a cellulose suspension.

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

[0104] (3) Add the solution in step (2) to a 100 mL quartz pressure-resistant bottle, seal it and add a magnetic rotor, and stir for 30 min under dark conditions.

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

[0106] (5) Determine the contents of lactic acid and formic acid in the system after the reaction in step (4) by high performance liquid chromatography.

[0107] Based on Figure 3From the experimental results of thermal catalysis, it can be seen that the conversion of cellulose at 30 °C is due to photocatalysis. When the temperature is higher than 40 °C, the yields of lactic acid and formic acid increase significantly under the synergistic effect of photocatalysis and thermal catalysis. When the temperature increases to 90 °C, the yields of lactic acid and formic acid reach the maximum. Therefore, the optimal reaction temperature for the photothermal catalytic process is 90 °C.

[0108] Application Example 5

[0109] This part studies the influence of the catalytic time in 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, and then 0.2 g of NaIO 4 was used, and the pH was adjusted to 3.0 with 0.1 mol·L -1 hydrochloric acid solution. The beaker was covered with aluminum foil to prevent the photocatalytic decomposition of periodate. After 4 h of oxidation reaction, 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) 30 mg of the Cu 0.1 CeO 2 @LDO photocatalyst prepared in Example 1 and 1.6 g of NaOH were added to the cellulose suspension prepared in step (1).

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

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

[0114] (5) The contents of lactic acid and formic acid in the system after the reaction in step (4) were determined by high performance liquid chromatography.

[0115] The results are as Figure 5 shown. When the reaction time is 6 h, the yields of lactic acid and formic acid reach the highest. Specifically, when the reaction time increases from 2 h to 6 h, the yields of lactic acid and formic acid show a rapid increasing trend; after 6 h, the yield of lactic acid decreases slightly, which may be due to the fact that the lactic acid produced undergoes side reactions and is decomposed partially due to the too long reaction time. Therefore, the optimal reaction time is 6 h.

[0116]

Performance Test

[0117] 1. Morphology and Structure

[0118] For Example 1 Cu 0.1 CeO 2 @LDO photocatalyst, Comparative Example 1 LDO, Comparative Example 3 Cu 0.1 CeO 2 Scanning electron microscopy tests were carried out, and the results are as 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 scanning electron microscopy image of the prepared Cu 0.1 CeO 2 nanoparticles. Combining Figure 6 c, 6d of Cu 0.1 CeO 2 @LDO photocatalyst scanning electron microscopy spectrum, it can be seen that Cu 0.1 CeO 2 @LDO photocatalyst has the typical layered structure of hydrotalcite and a large number of pores on the surface of hydrotalcite, and Cu 0.1 CeO 2 nanoparticles are evenly distributed on the surface of hydrotalcite. And after calcination, Cu 0.1 CeO 2 @LDO photocatalyst still retains the three-dimensional hydrangea structure of hydrotalcite, which helps to improve the dispersion and stability of Cu 0.1 CeO 2 nanoparticles on the catalyst surface.

[0119] To further evaluate the specific structure of the synthesized Cu 0.1 CeO 2 @LDO photocatalyst, XRD characterization was carried out on Cu 0.1 CeO 2 @LDO photocatalyst, LDO, Cu 0.1 CeO 2 The results are as Figure 7 shown; XPS characterization was carried out on Cu 0.1 CeO 2 @LDO photocatalyst, and the results are as Figure 8 shown.

[0120] Observation Figure 7 It can be seen from the figure that Cu 0.1 CeO 2 @LDO photocatalyst has the crystallization peak of LDO, and the spectrum of the composite material is very similar to that of Cu 0.1 CeO 2 spectrum, which indicates that Cu 0.1 CeO 2 is successfully loaded on the surface of LDO, and Cu 0.1CeO 2 The @LDO photocatalyst was successfully synthesized. In addition, Figure 8 as shown in 0.1 CeO 2 in the @LDO photocatalyst, the elements Ce, Cu, O, Mg, and Al coexist, proving that Cu was successfully doped into CeO 2 to form Cu 0.1 CeO 2 .

[0121] 2. Pore size

[0122] Figure 9 For the N 0.1 adsorption - desorption isotherms of LDO, Cu 2 CeO 0.1 CeO 2 @LDO photocatalyst, all three substances in the figure show a type - IV isotherm pattern, indicating that the Cu 2 CeO 0.1 @LDO photocatalyst belongs to mesoporous materials. The specific surface areas of LDO, Cu 2 CeO 0.1 CeO 2 and Cu 0.1 CeO 2 @LDO are 105.940 m 2 g -1 , 78.368 m 2 g -1 and 190.134 m 2 g -1 respectively.

[0123] Analyzing the above results, it can be seen that: Cu 0.1 CeO 2 @LDO, by virtue of the large - specific - surface - area structure of the LDO matrix, after compounding LDO and Cu 0.1 CeO 2 is not affected by the small - specific - surface - area Cu 0.1 CeO 2 but instead shows a larger specific surface area than LDO. The particularity of this result not only proves that the Cu 0.1 CeO 2 @LDO photocatalyst can generate more active sites due to the large surface area, greatly improving the catalytic conversion efficiency; but also shows that the Cu 0.1 CeO 2 @LDO photocatalyst exhibits a large - surface - area characteristic superior to 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 part, according to the determined parameter results, the materials obtained from Example 1 and Comparative Examples 1 to 8 were subjected to performance tests according to the following measurement methods, and the effects of material changes and reaction condition changes on the application performance were compared. The results are as Figure 10 shown.

[0126] Measurement method in this part:

[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 NaIO 4 was added and the pH was adjusted to 3.0 with 0.1 mol·L -1 hydrochloric acid solution. The beaker was covered with aluminum foil to prevent photocatalytic decomposition of periodate. After the oxidation reaction for 4 h, a few drops of 1 M NaOH were added to adjust the pH of the solution to neutrality, and a cellulose suspension was obtained.

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

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

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

[0131] (5) The content of lactic acid and formic acid in the system after the reaction in step (4) was determined by a high performance liquid chromatograph.

[0132] As can be seen from Figure 10 a, the yields of lactic acid and formic acid are generally average under the catalysis of a single material. After compounding, Cu 0.1 CeO 2 can be evenly distributed on the surface of three-dimensional embroidered LDO. The abundant pores and large specific surface area of LDO increase the active sites of the catalyst and improve the catalyst performance. Therefore, the yields of lactic acid and formic acid are significantly improved. Analyzing Figure 10 the data in b, it can be seen that the synthesis temperature of a single material also has a greater impact on the yields of lactic acid and formic acid. This is because it is not conducive to the formation of a three-dimensional hydrangea-like morphology of LDO at room temperature, and the photothermal catalytic performance of Cu 0.1 CeO 2 formed at a higher temperature is also poor. And compared with LDO, Cu 0.1 CeO 2The influence of semiconductor materials on the composite material is greater. From the result comparison 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, and the doping effect is the best when the molar ratio of copper to cerium is 1 / 10. Comparing the results of Example 1, Comparative Example 7, and Comparative Example 8, it can be seen that when the dosage of LDO is too much, the mass of Cu 0.1 CeO 2 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. When Cu 0.1 CeO 2 is used in too much amount, it cannot be evenly dispersed on the surface of LDO and is prone to form large aggregates, which is also 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 are dissolved in water, stirred and mixed, 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, characterized in that 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, characterized in that: In S1, the molar ratio of magnesium in magnesium salt, aluminum in aluminum salt, fumaric acid and urea is (6-13): (5-12): (2.5-5): (15-30).

4. The preparation method according to claim 1, characterized in that: 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, characterized in that: 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, characterized in that: 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 50-80wt% 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 Application of CeO2@LDO photocatalyst in photothermal catalysis of cellulose to produce lactic acid and formic acid, characterized in that: 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 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.

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 uniformly mixed, reacted at 25-95°C under a xenon lamp 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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