Method for efficiently catalyzing furfural to prepare cyclopentanone, and catalyst and preparation method therefor

Abstract

A method for efficiently catalyzing furfural to prepare cyclopentanone, and a catalyst and preparation method therefor, are disclosed, in the field of biomass catalytic conversion. The catalyst comprises uniformly dispersed metal active center nanoparticles and oxides obtained by LDHs calcination. The metal active center is single atom Pt/Cu alloy; the LDHs is used as a precursor to prepare a Cu-containing catalyst precursor; after a reduction in H.sub.2 atmosphere, small amount of Pt.sup.2+ is used for reacting with the Cu-containing catalyst precursor to obtain a monoatomic Pt/Cu catalyst; said catalyst is used to catalyze hydrogenation of an aqueous phase of furfural to prepare cyclopentanone, wherein the reaction temperature is 120-250° C., the reaction pressure is 0.1-5 MPa, the reaction time is 0.5-24 hours, and the reaction solvent is ultrapure water. Low-cost and efficient, the catalyst catalyzes the hydrogenation of an aqueous phase of furfural to prepare cyclopentanone. When the reaction is carried out at 160° C. at an initial pressure of 0.1 MPa for 1 hour, the furfural is completely converted, and the yield of the cyclopentanone reaches 99%.

Claims

1. A catalyst for preparing cyclopentanone by efficiently catalyzing the conversion of furfural, comprising: uniformly dispersed metal active center nanoparticles and an oxide obtained by calcination of layered double hydroxides (LDHs), wherein the metal active center comprises single atom Pt/Cu alloy, wherein Pt atom is loaded in situ onto Cu surface.

2. The catalyst according to claim 1, wherein the Cu content of the metal active center in the catalyst is 5-30 wt %, the Pt content is 0.01-3 wt %, and the particle size of the single atom Pt/Cu alloy in the metal activity center is 2-20 nm.

3. The catalyst according to claim 1, wherein the Cu content of the metal active center in the catalyst is 8-20 wt %, the Pt content is 0.05-1 wt %, and the particle size of the single atom Pt/Cu alloy in the metal activity center is 2-10 nm.

4. A method for preparing the catalyst of claim 1, comprising: obtaining a Cu-containing catalyst precursor by using LDHs as a precursor and performing a reduction reaction in a H2 atmosphere; reacting with Pt.sup.2+; and washing and drying to obtain the catalyst comprising the single atom Pt/Cu alloy metal active center.

5. The method according to claim 4, further comprising: reducing the Cu-containing catalyst precursor in a H2 atmosphere, with a reduction temperature at 400-650° C., and a reduction time from 5 minutes to 6 hours.

6. The method according to claim 5, further comprising: selecting Zn.sup.2+ or/and Mg.sup.2+ as a divalent cation of the LDHs lattice of the Cu-containing LDHs precursor, selecting Al.sup.3+ as a trivalent cation of the LDHs lattice of the Cu-containing LDHs precursor, wherein the metal active center ion inside the lattice is Cu.sup.2+; the molar ratio between the divalent cation Zn.sup.2+ or/and Mg.sup.2+ of the LDHs lattice and the metal active center ion Cu.sup.2+ inside the lattice is (0-10): 1, the divalent cation Zn.sup.2+ or/and Mg.sup.2+ of the LDHs lattice is not 0, and the molar ratio between all the divalent metal cations of the LDHs lattice Zn.sup.2+, Mg.sup.2+, Cu.sup.2+ and all trivalent metal cations of the LDHs lattice is in the range of (2-5): 1.

7. The method according to claim 6, wherein when preparing the Cu-containing catalyst precursor using hydrotalcite as the precursor, the LDHs precursor also contains tetravalent cations in the LDHs lattice, the tetravalent cations are selected as Zr.sup.4+, and the molar ratio of Zr.sup.4+ to the trivalent cation Al.sup.3+ is (0.1-1): 1.

8. The method according to claim 4, further comprising: after reduction by H.sub.2, sealing the Cu-containing catalyst precursor with de-oxygenated deionized water; under stirring and N.sub.2 protection, adding a Pt.sup.2+ solution dropwise to the liquid-sealed Cu-containing catalyst precursor, and reacting at 90-120° C. for 1-3 hours; and separating, washing, and drying to obtain the catalyst.

9. A method of using the catalyst of claim 1 to catalyze the conversion of furfural to produce cyclopentanone, further comprising: reacting at the temperature of 120 to 250° C., under the pressure of 0.1 to 5 MPa, wherein the reaction time being 0.5 to 24 hours, and the reaction solvent being ultrapure water.

10. The method according to claim 9, further comprising: reacting in a reactor, replacing air inside the reactor with hydrogen and maintaining appropriate pressure, the mass fraction of the substrate furfural being 1-20 wt %, the reaction temperature being 120-250° C., and the reaction pressure being 0.1-5 MPa, the reaction time being 0.5-24 hours, and the reaction solvent being ultrapure water.

11. A method for preparing the catalyst of claim 2, comprising: obtaining a Cu-containing catalyst precursor by using LDHs as a precursor and performing a reduction reaction to a H.sub.2 atmosphere; reacting with Pt.sup.2+; and washing and drying to obtain the catalyst comprising the monatomic PT/Cu metal active center.

12. The method according to claim 11, further comprising: reducing the Cu-containing catalyst precursor H.sub.2 atmosphere, with a reduction temperature at 400° C. to 650° C., and a reduction time from 5 minutes to 6 hours.

13. The method according to claim 12, further comprising: selecting Zn.sup.2+ or/and Mg.sup.2+ as a divalent cation of the LDHs lattice of the CU-containing LDHs precursor, selecting Al.sup.3+ as a trivalent cation of the LDHs lattice of the Cu.sup.2+; the molar ration between the divalent cation Zn.sup.2+ or/and Mg.sup.2+ of the LDHS lattice and the metal active Cu.sup.2+ inside the lattice is (0-10):1, the divalent cation Zn.sup.2+ or/and Mg.sup.2+ of the LDHs lattice is not 0, and the molar ratio between all the divalent metal cations of the LDHs lattice Zn.sup.2+, Mg.sup.2+, Cu.sup.2+ and all trivalent metal cations of the LDS lattice is in the range of (2-5):1.

14. The method according to claim 13, wherein when preparing the Cu-containing catalyst precursor using hydrotalcite as the precursor, the LDHs precursor also contains tetravalent cations in the LDHs lattice, the tetravalent cations are selected as Zr.sup.4+, and the molar ratio of Zr.sup.4+ to the trivalent cation of Al.sup.3+ is (0.1-1):1.

15. The method according to claim 11, further comprising: after reduction by H.sub.2, sealing the Cu-containing catalyst precursor with de-oxygenated deiodized water; under stirring and N.sub.2 protection, adding the Pt.sup.2+ solution dropwise to the liquid-sealed Cu-containing catalyst precursor, and reacting at 90-120° C. for 1-3 hours; and separating, washing and drying to obtain the catalyst.

16. A method of using the catalyst of claim 2 to catalyze the conversion of furfural to prepare cyclopentanone, further comprising; reacting at the temperature of 120 to 250° C., under the pressure of 0.1 to 5 MPa, wherein the reaction time being 0.5 to 24 hours, and the reaction solvent being ultrapure water.

17. The method according to claim 16, further comprising: reacting in a reactor, replacing air inside the reactor with hydrogen and maintaining appropriate pressure, the mass fraction of the substrate furfural being 1-20 wt %, the reaction temperature being 120-250° C., and the reaction pressure being 0.1-5 MPA, the reaction time being 0.5-24 hours, and the reaction solvent being ultrapure water.

18. A method of preparing the catalyst of claim 3, comprising: obtaining a Cu-containing catalyst precursor by using hydrotalcite as a precursor and performing a reduction reaction in a H.sub.2 atmosphere; reacting with Pt.sup.2+; and washing and drying to obtain the catalysts comprising the single atom Pt/Cu alloy metal active center.

19. The method according to claim 18, further comprising: reducing the Cu-containing catalyst precursor in a H.sub.2 atmosphere, with a reduction temperature at 400-500° C., and a reduction time of 5 minutes to 6 hours.

20. The method according to claim 19, further comprising: selecting Zn.sup.2+ or/and Mg.sup.2+ as a divalent cation of the LDHs lattice of the CU-containing LDHs precursor, Selecting Al.sup.3+ as a trivalent cation of the LDHs lattice of the Cu-containing LDHs precursor, wherein the metal active center ion inside the lattice is Cu.sup.2+; the molar ratio between the divalent cation Zn.sup.2+ or/and Mg.sup.2+ of the LDHs lattice and the metal active center ion cu.sup.2+ inside the lattice is (0-10):1, the divalent cation Zn.sup.2+ or/and Mg.sup.2+ of the LDHs lattice is not 0, and the molar ratio between all the divalent metal cations of the LDHs lattice Zn.sup.2+, Mg.sup.2+, Cu.sup.2+ and all trivalent metal cations of the LDHs lattice is in the range of (2-5):1.

Description

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(1) The present disclosure will be further described below with the preferred embodiment, but the present invention is not limited to the following examples.

Embodiment 1

(2) Step A: Cu(NO.sub.3).sub.2.Math.3H.sub.2O (14 mmol), Zn(NO.sub.3).sub.2.Math.6H.sub.2O (42 mmol), Al(NO.sub.3).sub.3.Math.9H.sub.2O (12 mmol), and ZrO(NO.sub.3).sub.2.Math.6H.sub.2O (6 mmol) are dissolved in 200 mL deionized water as solution A, NaOH (0.156 mol), Na.sub.2CO.sub.3 (0.024 mol) are dissolved into 200 mL deionized water as solution B. Subsequently, at a constant pH (10.0), solutions A and B are simultaneously added dropwise to a four-necked flask containing 200 mL of deionized water. After crystallization at 65° C. for 12 hours, the solid is filtered, washed with deionized water several times until the filtrate is neutral, and then dried overnight at 80° C. to obtain a CuZnAlZr-LDHs sample.

(3) Step B: add the CuZnAlZr-LDHs synthesized in step A into a tube furnace, under H.sub.2 atmosphere (40 mL min.sup.−1), raise the temperature from room temperature to 450° C. at a rate of 2° C. min.sup.−1 and maintained for 2 hours, to obtained Cu—Zn(Al)(Zr)O. Take 1 g reduced Cu—Zn(Al)(Zr)O, liquid-seal it with 5 mL deionized water with oxygen removed, pour it into a round bottom flask, and add Pt.sup.2+ solution under vigorous stirring and N.sub.2 protection. After that, replacement reaction is proceeded with a reflux condenser at 100° C. under vigorous stirring for 2 hours. The mud-like substance separated by centrifugation is washed three times with deionized water, and dried in vacuum at 40° C. for 24 hours.

(4) A Pt/Cu—Zn(Al)(Zr)O catalyst is thus prepared. The actual loading of Pt is 0.1%, the actual loading of Cu is 11%, and particle size of the metal center is 2-20 nm.

(5) The Pt/Cu—Zn(Al)(Zr)O catalyst obtained in embodiment 1 is used to catalyze the furfural hydro-conversion. Add 0.5 g of furfural, 0.03 g catalyst, 10 mL ultrapure water to the lining of autoclave, install the autoclave, fill H.sub.2 from the air inlet, replace the air in autoclave 5 times, then fill with 0.1 MPa H.sub.2, seal the autoclave. The autoclave is heated to a preset temperature. The pressure is about 0.5 MPa at 160° C., and the timing is started. The reaction is continued for 10 hours. During the process, H.sub.2 is continuously replenished to 0.5 MPa. After the reaction is completed, it is cooled to room temperature, liquid in the reactor is centrifuged, and product is quantitatively analyzed by GC. The furfural conversion rate on Pt/Cu—Zn(Al)(Zr)O catalyst is measured to be 100%, and the selectivity to cyclopentanone is 99%.

Embodiment 2

(6) Step A: Cu(NO.sub.3).sub.2.Math.3H.sub.2O (10 mmol), Zn(NO.sub.3).sub.2.Math.6H.sub.2O (46 mmol), Al(NO.sub.3).sub.3.Math.9H.sub.2O (12 mmol), and ZrO(NO.sub.3).sub.2.Math.6H.sub.2O (6 mmol) are dissolved in 200 mL deionized water as solution A, NaOH (0.156 mol) and Na.sub.2CO.sub.3 (0.024 mol) are dissolved into 200 mL deionized water as solution B. Subsequently, at a constant pH (10.0), solutions A and B are simultaneously added dropwise to a four-necked flask containing 200 mL of deionized water. After crystallization at 65° C. for 12 hours, the solid is filtered, washed with deionized water several times until the filtrate is neutral, and then dried overnight at 80° C. to obtain a CuZnAlZr-LDHs sample.

(7) Step B: add the CuZnAlZr-LDHs synthesized in step A into a tube furnace, under H.sub.2 atmosphere (40 mL min.sup.−1), raise the temperature from room temperature to 450° C. at a rate of 2° C. min.sup.−1 and maintained for 2 hours, to obtained Cu—Zn(Al)(Zr)O. Take 1 g reduced Cu—Zn(Al)(Zr)O, liquid-seal it with 5 mL deionized water with oxygen removed, pour it into a round bottom flask, and add Pt.sup.2+ solution under vigorous stirring and N.sub.2 protection. After that, replacement reaction is proceeded with a reflux condenser at 100° C. under vigorous stirring for 2 hours. The mud-like substance separated by centrifugation is washed three times with deionized water, and dried in vacuum at 40° C. for 24 hours.

(8) A Pt/Cu—Zn(Al)(Zr)O catalyst is thus prepared. The actual loading of Pt is 0.1%, the actual loading of Cu is 8%, and particle size of the metal center is 2-20 nm.

(9) The Pt/Cu—Zn(Al)(Zr)O catalyst obtained in embodiment 2 is used to catalyze the furfural hydro-conversion. Add 0.5 g of furfural, 0.03 g catalyst, 10 mL ultrapure water to the lining of autoclave, install the autoclave, fill H.sub.2 from the air inlet, replace the air in autoclave 5 times, then fill with 0.1 MPa H.sub.2, seal the autoclave. The autoclave is heated to a preset temperature. The pressure is about 0.5 MPa at 160° C., and the timing is started. The reaction is continued for 10 hours. During the process, H.sub.2 is continuously replenished to 0.5 MPa. After the reaction is completed, it is cooled to room temperature, liquid in the reactor is centrifuged, and product is quantitatively analyzed by GC. The furfural conversion rate on Pt/Cu—Zn(Al)(Zr)O catalyst is measured to be 100%, and the selectivity to cyclopentanone is 92%.

Embodiment 3

(10) Step A: Cu(NO.sub.3).sub.2.Math.3H.sub.2O (20 mmol), Zn(NO.sub.3).sub.2.Math.6H.sub.2O (36 mmol), Al(NO.sub.3).sub.3.Math.9H.sub.2O (12 mmol), and ZrO(NO.sub.3).sub.2.Math.6H.sub.2O (6 mmol) are dissolved in 200 mL deionized water as solution A, NaOH (0.156 mol), Na.sub.2CO.sub.3(0.024 mol) are dissolved into 200 mL deionized water as solution B. Subsequently, at a constant pH (10.0), solutions A and B are simultaneously added dropwise to a four-necked flask containing 200 mL of deionized water. After crystallization at 65° C. for 12 hours, the solid is filtered, washed with deionized water several times until the filtrate is neutral, and then dried overnight at 80° C. to obtain a CuZnAlZr-LDHs sample.

(11) Step B: add the CuZnAlZr-LDHs synthesized in step A into a tube furnace, under H.sub.2 atmosphere (40 mL min.sup.−1), raise the temperature from room temperature to 450° C. at a rate of 2° C. min.sup.−1 and maintained for 2 hours, to obtained Cu—Zn(Al)(Zr)O. Take 1 g reduced Cu—Zn(Al)(Zr)O, liquid-seal it with 5 mL deionized water with oxygen removed, pour it into a round bottom flask, and add Pt.sup.2+ solution under vigorous stirring and N.sub.2 protection. After that, replacement reaction is proceeded with a reflux condenser at 100° C. under vigorous stirring for 2 hours. The mud-like substance separated by centrifugation is washed three times with deionized water, and dried in vacuum at 40° C. for 24 hours.

(12) A Pt/Cu—Zn(Al)(Zr)O catalyst is thus prepared. The actual loading of Pt is 0.1%, the actual loading of Cu is 17%, and particle size of the metal center is 2-20 nm.

(13) The Pt/Cu—Zn(Al)(Zr)O catalyst obtained in embodiment 3 is used to catalyze the furfural hydro-conversion. Add 0.5 g of furfural, 0.03 g catalyst, 10 mL ultrapure water to the lining of autoclave, install the autoclave, fill H.sub.2 from the air inlet, replace the air in autoclave 5 times, then fill with 0.1 MPa H.sub.2, seal the autoclave. The autoclave is heated to a preset temperature. The pressure is about 0.5 MPa at 160° C., and the timing is started. The reaction is continued for 10 hours. During the process, H.sub.2 is continuously replenished to 0.5 MPa. After the reaction is completed, it is cooled to room temperature, liquid in the reactor is centrifuged, and product is quantitatively analyzed by GC. The furfural conversion rate on Pt/Cu—Zn(Al)(Zr)O catalyst is measured to be 100%, and the selectivity to cyclopentanone is 90%.

(14) Experimental Control 1

(15) Step A: Cu(NO.sub.3).sub.2.Math.3H.sub.2O (14 mmol), Zn(NO.sub.3).sub.2.Math.6H.sub.2O (42 mmol), Al(NO.sub.3).sub.3.Math.9H.sub.2O (12 mmol), and ZrO(NO.sub.3).sub.2.Math.6H.sub.2O (6 mmol) are dissolves in 200 mL deionized water as solution A, and NaOH (0.156 mol), Na.sub.2CO.sub.3 (0.024 mol) are dissolved into 200 mL deionized water as solution B. At a constant pH (10.0), solutions A and B are simultaneously added dropwise to a four-necked flask containing 200 mL of deionized water. After crystallization at 65° C. for 12 hours, the solid is filtered, washed with deionized water several times until the filtrate is neutral, and dried overnight at 80° C. to obtain a CuZnAlZr-LDHs sample.

(16) Step B: add the CuZnAlZr-LDHs synthesized in step A into a tube furnace, raise the temperature at a rate of 2° C. min.sup.−1 from room temperature to 450° C. and maintained for 2 hours under H.sub.2 (40 mL min.sup.−1) atmosphere, Cu—Zn(Al)(Zr)O is thus obtained.

(17) The Cu—Zn(Al)(Zr)O catalyst is prepared and used as the control. The actual loading of Cu is 11%, and the center particle size of the metal is 2-20 nm.

(18) The Cu—Zn(Al)(Zr)O catalyst obtained in Experimental control 1 is used to catalyze the furfural hydro-conversion. Add 0.5 g of furfural, 0.03 g catalyst, 10 mL ultrapure water to the lining of autoclave, install the autoclave, fill H.sub.2 from the air inlet, replace the air in autoclave 5 times, then fill with 0.1 MPa H.sub.2, seal the autoclave. The autoclave is heated to a preset temperature. The pressure is about 0.5 MPa at 160° C., and the timing is started. The reaction is continued for 10 hours. During the process, H.sub.2 is continuously replenished to 0.5 MPa. After the reaction is completed, it is cooled to room temperature, liquid in the reactor is centrifuged, and product is quantitatively analyzed by GC. The furfural conversion rate on the Cu—Zn(Al)(Zr)O catalyst is measured to be 24%, and the selectivity to cyclopentanone is 9%.

(19) It can be seen by comparing the outcomes of the embodiments and controlled experiment that the Pt/Cu catalyst has a superior function of hydrogenation of furfural to produce cyclopentanone.