MESOPOROUS CERIUM OXIDE NANO-MATERIAL AND PREPARATION METHOD AND APPLICATION THEREOF

Abstract

A mesoporous cerium oxide nano-material and a preparation method and an application thereof are provided in the present disclosure, belonging to the technical field of porous materials. The preparation method includes the following steps: using porous organic frameworks material as a templating agent, impregnating and adsorbing cerium salt precursor under an action of alkali, and removing the templating agent by roasting pyrolysis to obtain the mesoporous cerium oxide nano-material. POFs is carbonized into mesoporous carbon materials by calcination in inert atmosphere, which supports the mesoporous channels of cerium oxide, and then the carbonized carbon materials of POFs are removed by calcination in air atmosphere, forming the mesoporous structure of cerium oxide. The mesoporous cerium oxide nano-material prepared by the present disclosure has a high specific surface area and mesoporous structure, and is used as a catalytic material or catalyst carrier.

Claims

1. A preparation method of a mesoporous cerium oxide nano-material, comprising following steps: using porous organic frameworks material as a templating agent, impregnating and adsorbing cerium salt precursor under an action of alkali, and removing the templating agent by roasting pyrolysis to obtain the mesoporous cerium oxide nano-material; wherein the cerium salt comprises at least one of cerium nitrate, cerium chloride and cerium sulfate; and the alkali comprises at least one of sodium hydroxide, potassium hydroxide and ammonia water.

2. The preparation method according to claim 1, wherein a mass/molar ratio of the porous organic frameworks material, cerium salt and alkali is 2 grams:10-20 millimoles:30-80 millimoles.

3. The preparation method according to claim 1, wherein the porous organic frameworks material is obtained from melamine and terephthalaldehyde through aldehyde-amine polycondensation reaction.

4. The preparation method according to claim 1, wherein a method for the adsorbing comprises: dispersing the porous organic frameworks material into a cerium salt solution, adding an alkali solution under a stirring condition, and completing an adsorbing process after a reaction is completed.

5. The preparation method according to claim 4, wherein a concentration of the cerium salt solution is 100-200 millimoles per liter; and a concentration of the alkali solution is 0.1 Moles per liter.

6. The preparation method according to claim 1, wherein a method of the roasting pyrolysis comprises: collecting solid products after adsorption, drying, heating to 600 degrees Celsius at a heating rate of 4 degrees Celsius per minute in an inert atmosphere for 2 hours, and then roasting at 600 degrees Celsius for 2 hours in an air atmosphere.

7. The preparation method according to claim 6, wherein the inert atmosphere comprises argon atmosphere, nitrogen atmosphere, helium atmosphere, neon atmosphere, krypton atmosphere or xenon atmosphere.

8. A mesoporous cerium oxide nanomaterial prepared by the preparation method according to claim 1.

9. An application of the mesoporous cerium oxide nano-material according to claim 8 in industrial catalysis, fuel cell preparation or sensitive device preparation.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which constitute a part of the present disclosure, are used to provide a further understanding of the present application, and the illustrative embodiments of the present disclosure and their descriptions are used to explain the present application, and do not constitute an improper limitation of the present disclosure. In the attached drawings:

[0037] FIG. 1 is a transmission electron microscope diagram of mesoporous CeO.sub.2-1 prepared in Embodiment 1 of the present disclosure.

[0038] FIG. 1A shows a microscopic morphology a of mesoporous CeO.sub.2-1 prepared in Embodiment 1 by transmission electron microscopy.

[0039] FIG. 1B shows a microscopic morphology b of mesoporous CeO.sub.2-1 prepared in Embodiment 1 by transmission electron microscopy.

[0040] FIG. 2A is a diagram of nitrogen adsorption and desorption of mesoporous CeO.sub.2-1 material prepared in Embodiment 1 of the present disclosure.

[0041] FIG. 2B is a diagram of pore size distribution of mesoporous CeO.sub.2-1 material prepared in Embodiment 1 of the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0042] In the following, the technical schemes in the embodiments of the present disclosure are clearly and completely described with reference to the attached drawings. Obviously, the described embodiments form only a part of the embodiments of the present disclosure, but not the whole embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without creative labor belong to the scope of protection of the present disclosure.

Embodiment 1

Preparation of a Mesoporous Cerium Oxide Nano-Material

[0043] 5 g of melamine (purity not less than 99%) and 8 g of terephthalaldehyde (purity not less than 99%) are added into 250 mL of dimethyl sulfoxide (purity not less than 99.9%), heated to 180 C. at the rate of 20 C./min in argon atmosphere, and stirred at this temperature for 72 h, and the solid product is collected and washed with ethanol for three times, and then dried under vacuum (vacuum degree 0.7 atm) at 80 C. for 6 h to obtain the POFs material; and [0044] 2 g of the POFs material is ultrasonically dispersed into 100 mL of cerium nitrate solution (concentration of 100 mmol/L), and then NaOH solution with concentration of 0.1 mol/L prepared from 40 mmol of NaOH is slowly dropped under vigorous stirring, and the reaction is lasted for 3 h; the solid products are collected and dried, and then placed in a muffle furnace under argon atmosphere for roasting at a heating rate of 4 C./min to 600 C. for 2 h, and then roasted in air atmosphere at 600 C. for 2 h to obtain the mesoporous cerium oxide nano-material, which is recorded as mesoporous CeO.sub.2-1 nano-material.

[0045] The specific surface area of the mesoporous CeO.sub.2-1 nano-material is 138 m.sup.2/g, and the average pore size distribution is 22 nm.

Embodiment 2

[0046] 5 g of melamine (purity not less than 99%) and 8 g of terephthalaldehyde (purity not less than 99%) are added into 250 mL of dimethyl sulfoxide (purity not less than 99.9%), heated to 180 C. at the rate of 20 C./min in argon atmosphere, and stirred at this temperature for 72 h, and the solid products are collected and washed with ethanol for three times, and then dried under vacuum (vacuum degree 0.7 atm) at 80 C. for 6 h to obtain the POFs material; and

[0047] 2 g of the POFs material is ultrasonically dispersed into 100 mL of cerium nitrate solution (concentration of 150 mmol/L), and then NaOH solution with concentration of 0.1 mol/L prepared from 60 mmol of NaOH is slowly dropped under vigorous stirring, and the reaction is lasted for 3 h; the solid products are collected and dried, and then placed in a muffle furnace under argon atmosphere for roasting at a heating rate of 4 C./min to 600 C. for 2 h, and then roasted in air atmosphere at 600 C. for 2 h to obtain the mesoporous cerium oxide nano-material, which is recorded as mesoporous CeO.sub.2-2 nano-material.

[0048] The specific surface area of the mesoporous CeO.sub.2-2 nano-material is 136.5 m.sup.2/g, and the average pore size distribution is 21 nm.

Embodiment 3

[0049] 5 g of melamine (purity not less than 99%) and 8 g of terephthalaldehyde (purity not less than 99%) are added into 250 milliliters (mL) of dimethyl sulfoxide (purity not less than 99.9%), heated to 180 C. at the rate of 20 C./min in argon atmosphere, and stirred at this temperature for 72 h, and the solid product is collected and washed with ethanol for three times, and then dried under vacuum (vacuum degree 0.7 atm) at 80 C. for 6 h to obtain the POFs material; [0050] 2 g of the POFs material is ultrasonically dispersed into 100 mL of cerium nitrate solution (concentration of 200 mmol/L), and then NaOH solution with concentration of 0.1 mol/L prepared from 80 mmol of NaOH is slowly dropped under vigorous stirring, and the reaction is lasted for 3 h; the solid products are collected and dried, and then placed in a muffle furnace under argon atmosphere for roasting at a heating rate of 4 C./min to 600 C. for 2 h, and then roasted in air atmosphere at 600 C. for 2 h to obtain the mesoporous cerium oxide nano-material, which is recorded as mesoporous CeO.sub.2-3 nano-material.

[0051] The specific surface area of the mesoporous CeO.sub.2-3 nano-material is 129 m.sup.2/g, and the average pore size distribution is 21 nm.

Comparative Embodiment 1

[0052] Mesoporous cerium oxide material is prepared by using ordered mesoporous carbon material CMK-3 as a hard template, and the specific method is as follows:

[0053] 2 g of the CMK-3 material is ultrasonically dispersed into 100 mL of cerium nitrate solution (concentration of 200 mmol/L), and NaOH solution with concentration of 0.1 mol/L prepared from 80 mmol of NaOH is slowly added dropwise under vigorous stirring, and reacted for 3 h; the solid products are collected and dried, and then placed in a muffle furnace under argon atmosphere for roasting at a heating rate of 4 C./min to 600 C. for 2 h, and then roasted in air atmosphere at 600 C. for 2 h to obtain the mesoporous cerium oxide nano-material, which is recorded as mesoporous CeO.sub.2-4 nano-material.

[0054] The specific surface area of mesoporous CeO.sub.2-4 nano-material is 108 m.sup.2/g, and the average pore size is 12 nm.

Comparative Embodiment 2

[0055] The mesoporous cerium oxide material is prepared by using surfactant cetyltrimethyl ammonium bromide as a soft template, and the specific method is as follows:

[0056] 2 g of cetyltrimethyl ammonium bromide is ultrasonically dispersed into 100 mL of cerium nitrate solution (concentration of 200 mmol/L), then NaOH solution with concentration of 0.1 mol/L prepared from 80 mmol of NaOH is slowly added dropwise with vigorous stirring, and reacted for 3 h; the solid products are collected and dried, and then placed in a muffle furnace under argon atmosphere for roasting at a heating rate of 4 C./min to 600 C. for 2 h, and then roasted in air atmosphere at 600 C. for 2 h to obtain the mesoporous cerium oxide nano-material, which is recorded as mesoporous CeO.sub.2-5 nano-material.

[0057] The specific surface area of mesoporous CeO.sub.2-5 nano-materials is 68 m.sup.2/g, and the average pore size is 8 nm.

Comparative Embodiment 3

[0058] Compared with Embodiment 1, the only difference is that the roasting is only carried out in the air atmosphere, specifically, the roasting is carried out in the air atmosphere at a heating rate of 4 C./min to 600 C. for 4 h, then the mesoporous cerium oxide nano-material is prepared, which is recorded as mesoporous CeO.sub.2-6 nano-material.

[0059] The specific surface area of mesoporous CeO.sub.2-6 nanomaterials is 76.5 m.sup.2/g, and the average pore size is 7.6 nm.

Comparative Embodiment 4

[0060] Compared with Embodiment 1, the only difference is that the roasting is only carried out in argon atmosphere, specifically, the roasting is carried out in argon atmosphere at a heating rate of 4 C./min to 600 C. for 4 h, then the mesoporous cerium oxide nano-material is prepared, which is recorded as mesoporous CeO.sub.2-7 nano-material.

[0061] The specific surface area of mesoporous CeO.sub.2-7 nano-materials is 118 m.sup.2/g, and the average pore size is 20 nm.

Comparative Embodiment 5

[0062] Compared with Embodiment 1, the only difference is that sodium hydroxide solution is not added, and it is only absorbed by POFs material and then dried and roasted, then the mesoporous cerium oxide nano-material is prepared, which is named mesoporous CeO.sub.2-8 nano-material.

[0063] The specific surface area of mesoporous CeO.sub.2-8 nano-materials is 113 m.sup.2/g, and the average pore size is 18 nm.

Test Embodiment

[0064] CeO.sub.2-1 nano-material prepared in Embodiment 1 and mesoporous CeO.sub.2-5 nano-material prepared in Comparative embodiment 2 are dispersed in 1 mg/mL aqueous solution of palladium acetate by ultrasound, and then 0.1 mol/L aqueous solution of sodium borohydride is added dropwise to prepare Pd(2%)/CeO.sub.2-1 and Pd(2%)/CeO.sub.2-5 catalysts with 2% Pd loading.

[0065] Pd(2%)/CeO.sub.2-1 and Pd(2%)/CeO.sub.2-5 catalysts are applied to the selective catalytic hydrogenation of phenylacetylene to styrene at room temperature and pressure.

[0066] On the premise of complete conversion of phenylacetylene, the selectivity of styrene catalyzed by Pd(2%)/CeO.sub.2-1 is 97%, and the selectivity of styrene catalyzed by Pd(2%)/CeO.sub.2-5 is 76%.

[0067] The results show that the mesoporous cerium oxide carriers with high specific surface area and pore size of 22 nm prepared by the present disclosure have excellent effect in selective catalytic hydrogenation.

[0068] FIG. 1A and FIG. 1B are the transmission electron microscope diagrams of mesoporous CeO.sub.2-1 prepared in Embodiment 1 of the present disclosure. Among them, FIG. 1A and FIG. 1B are transmission electron microscope images of mesoporous CeO.sub.2-1 prepared in Embodiment 1 from different angles, and it may be seen from FIG. 1A and FIG. 1B that CeO.sub.2-1 has a porous and loose structure.

[0069] FIG. 2A is a diagram of nitrogen adsorption and desorption and FIG. 2B is a diagram of pore size distribution of mesoporous CeO.sub.2-1 material prepared in Embodiment 1 of the present disclosure. It may be seen from FIG. 2A and FIG. 2B that CeO.sub.2-1 material has a wide pore size distribution.

[0070] Each embodiment in this specification is described in a progressive way, and each embodiment focuses on the differences from other embodiments, so it is only necessary to refer to the same and similar parts between each embodiment.

[0071] The above description of the disclosed embodiments enables those skilled in the art to make or use the present disclosure. Many modifications to these embodiments will be obvious to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.