METHOD FOR PREPARING TWO-DIMENSIONAL SHEET-SHAPED CU-MOF MATERIAL

Abstract

A method for preparing a two-dimensional sheet-shaped Cu-MOF material, includes mixing Cu-BTC with an alkaline solution at a certain solid-liquid ratio by stirring, reacting at a temperature of 25 to 120 C., filtering, washing with ionized water and drying under vacuum, to obtain a two-dimensional sheet-shaped Cu-MOF material, wherein the alkaline solution is at least one of urea, sodium carbonate, sodium bicarbonate, aqueous ammonia, sodium hydroxide or potassium hydroxide. The method has the characteristics of mild operation conditions, controllable transition process, high reaction yield and easy production at large scale, and exhibits excellent oxidation performance in styrene oxidation.

Claims

1. A method for preparing a two-dimensional sheet-shaped Cu-MOF material, comprising mixing Cu-BTC with an alkaline solution at a certain solid-liquid ratio by stirring, reacting at a temperature of 25 to 120 C., filtering, washing with ionized water and drying under vacuum, to obtain a two-dimensional sheet-shaped Cu-MOF material, wherein the alkaline solution is at least one of urea, sodium carbonate, sodium bicarbonate, aqueous ammonia, sodium hydroxide or potassium hydroxide.

2. The method according to claim 1, wherein the raw material Cu-BTC refers to a MOF material having a three-dimensional structure which has been industrialized in the prior art, and has a CAS number of 51937-85-0.

3. The method according to claim 1, wherein the two-dimensional sheet-shaped Cu-MOF is a general term for a plurality of compounds having a two-dimensional sheet-shaped structure formed by the coordination assembly of Cu and trimesic acid.

4. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is less than 1/30 g/ml.

5. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/150solid-liquid ratio 1/80 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/100solid-liquid ratio <1/50 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/70solid-liquid ratio <1/30 g/ml.

6. The method according to claim 1, wherein the pH of the alkaline solution is 7 to 12.

7. The method according to claim 1, wherein the pH of the alkaline solution is 9 to 12.

8. The method according to claim 1, wherein the reaction temperature is 25 to 120 C.

9. The method according to claim 1, wherein the reaction time is 1-24 hrs.

10. The method according to claim 9, wherein the reaction time is 1-5 hrs.

11. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is 1/150solid-liquid ratio 1/40 g/ml.

12. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is 1/110solid-liquid ratio 1/50 g/ml.

13. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/150solid-liquid ratio 1/80 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/100solid-liquid ratio <1/50 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/60solid-liquid ratio 1/40 g/ml.

14. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/150solid-liquid ratio 1/80 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/90solid-liquid ratio 1/60 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/70solid-liquid ratio <1/30 g/ml.

15. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/150solid-liquid ratio 1/80 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/90solid-liquid ratio 1/60 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/60solid-liquid ratio 1/40 g/ml.

16. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/110solid-liquid ratio 1/90 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/100solid-liquid ratio <1/50 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/70solid-liquid ratio <1/30 g/ml.

17. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/110solid-liquid ratio 1/90 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/100solid-liquid ratio <1/50 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/60solid-liquid ratio 1/40 g/ml.

18. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/110solid-liquid ratio 1/90 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/90solid-liquid ratio 1/60 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/70solid-liquid ratio <1/30 g/ml.

19. The method according to claim 1, wherein the solid-liquid ratio of the Cu-BTC to the alkaline solution is such that when the pH of the alkaline solution is 7 to 9, 1/110solid-liquid ratio 1/90 g/ml; when the pH of the alkaline solution is 9 to 10.5, 1/90solid-liquid ratio 1/60 g/ml; and when the pH of the alkaline solution is 10.5 to 12, 1/60solid-liquid ratio 1/40 g/ml.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG. 1 compares the XRD patterns of the crystal structures before and after transition at various temperatures (25 C., 80 C., and 120 C.);

[0020] FIG. 2 is a scanning electron microscopy (SEM) image of the crystal morphology after transition at various temperatures (25 C., and 80 C.); and

[0021] FIG. 3 is a scanning electron microscopy (SEM) image of the crystal morphology after transition at different solid-liquid ratios.

DETAILED DESCRIPTION

[0022] The present invention will be further described below by way of examples. The following examples are provided for a better understanding of the present invention; however, the present invention is not limited thereto.

[0023] The methods given in examples below are all conventional methods, unless it is otherwise stated; and the reagents and raw materials are all commercially available unless otherwise indicated.

[0024] The specific mode of catalytic oxidation of styrene in the following examples is as follows:

[0025] 10 mg of a catalyst is fed to a 40 ml stoppered glass flask, 4 ml of acetonitrile, 2 mmol of styrene and 6 mmol of t-butyl hydroperoxide (TBHP) are added, respectively, and stirred at 75 C. for 5 h.

Example 1

[0026] Cu-BTC and an urea solution with pH=9 were mixed at a solid-liquid ratio of 1/100 g/ml, stirred at 25 C. for 5 hrs, filtered, washed and dried to obtain a two-dimensional sheet-shaped Cu-MOF-25. The thickness was from 30 nm to 100 nm. In the catalytic oxidation experiment of styrene, the conversion rate reached 98.97% after 5 h reaction.

Example 2

[0027] Cu-BTC and a sodium hydroxide solution with pH=10 were mixed at a solid-liquid ratio of 1/80 g/ml, stirred at 80 C. for 2 hrs, filtered, washed and dried to obtain a two-dimensional sheet-shaped Cu-MOF-80. The thickness was from 200 nm to 300 nm. In the catalytic oxidation experiment of styrene, the conversion rate reached 97.42% after 5 h reaction.

Example 3

[0028] Cu-BTC and aqueous ammonia with pH=12 were mixed at a solid-liquid ratio of 1/50 g/ml, stirred at 120 C. for 1 hr, filtered, washed and dried to obtain a two-dimensional sheet-shaped Cu-MOF-120. The thickness was from 400 nm to 500 nm. In the catalytic oxidation experiment of styrene, the conversion rate reached 97.15% after 5 h reaction.

[0029] FIG. 1 compares the XRD patterns of the crystal structures before and after transition of Cu-BTC in the above examples, in which a) is Cu-BTC before transition, b) is an XRD pattern of Cu-MOF after transition at 25 C. in Example 1, c) is an XRD pattern of Cu-MOF after transition at 80 C. in Example 2, and d) is an XRD pattern of Cu-MOF after transition at 120 C. in Example 3. A scanning electron microscopy (SEM) image of the crystal morphology after the transition is shown in FIG. 2, where a is an SEM image of Cu-MOF after transition at 25 C. in Example 1, and b is an SEM image of Cu-MOF after transition at 80 C. in Example 2.

Comparative Example 1

[0030] Cu-BTC and an urea solution with pH=12 were mixed at a solid-liquid ratio of 1/30 g/ml, stirred at 120 C. for 1 hr, filtered, washed, and dried. However, Cu-BTC fails to transition to two-dimensional Cu-MOF, as shown in FIG. 3a.

Comparative Example 2

[0031] Cu-BTC and an sodium hydroxide solution with pH=10 were mixed at a solid-liquid ratio of 1/40 g/ml, stirred at 80 C. for 2 hr, filtered, washed, and dried. However, Cu-BTC fails to transition to two-dimensional Cu-MOF, as shown in FIG. 3a.

Comparative Example 3

[0032] When the performance of Cu-BTC was characterized by the conversion rate at 5 h of catalytic oxidation of styrene, the conversion rate was 42.32%. It can be seen that the two-dimensional sheet-shaped MOF material has more active sites and higher catalytic activity than the conventional MOF material.