Catalytic Wet Oxidation of Lactose

Abstract

A process for converting lactose into carbon dioxide and/or carbon monoxide using catalytic wet oxidation. Oxygen gas and an aqueous solution of lactose are fed to a reactor comprising a Pt/Al2O3 catalyst, a Mn/Ce catalyst or a Pt/Mn—Ce catalyst, and the lactose is oxidized in the reactor at elevated temperature and pressure to produce at least one of small organic acids, carbon dioxide, carbon monoxide, water and combinations thereof. The small organic acids may be further degraded by feeding the small organic acids and oxygen gas into a reactor containing a Mn/Ce catalyst and oxidizing the small organic acids to water and at least one of carbon dioxide, carbon monoxide and combinations thereof.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an exemplary flow system used for the catalytic wet oxidation of lactose.

FIG. 2 is a calibration chart illustrating the flow rates of oxygen gas with respect to the corresponding scale display of a mass flow controller.

FIG. 3 is a calibration curve of lactose concentration (mol/L) versus peak height (cm) obtained by HPLC analysis.

FIG. 4 is a calibration curve of lactobionic acid concentration (mol/L) versus peak height (cm) obtained by HPLC analysis.

FIG. 5 is a calibration curve of malic acid and succinic acid concentrations (mol/L) versus peak height (cm) obtained by HPLC analysis.

FIG. 6 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pt/Al₂O₃ catalyst at 100° C. and 150° C. The initial concentration of lactose is 0.08 mol/L.

FIG. 7 is a chromatogram obtained from the conversion of lactose over a Pt/Al₂O₃ catalyst (T=100° C.; system pressure=85 psig; liquid feed rate=36-40 ml/min; and O₂ supply rate=0.7397 L/min).

FIG. 8 is a chromatogram obtained from the conversion of lactose over a Pt/Al₂O₃ catalyst (T=150° C.; system pressure=85 psig; liquid feed rate=39-42 ml/min; and O₂ supply rate=0.7397 L/min).

FIG. 9 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pt/Al₂O₃ catalyst at O₂ flow rates of 0.74 L/min and 1.18 L/min.

FIG. 10 is a chromatogram obtained from the conversion of lactose over a Pt/Al₂O₃ catalyst (T=150° C.; system pressure=85 psig; liquid feed rate=32-38 ml/min; and O₂ supply rate=1.1777 L/min).

FIG. 11 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pt/Al₂O₃ catalyst at feed rates of 32-45 ml/min and 5-12 ml/min.

FIG. 12 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pt/Al₂O₃ catalyst at 170° C.

FIG. 13 is a chromatogram obtained from the conversion of lactose over a Pt Al₂O₃ catalyst (T=150° C.; system pressure 85 psig; liquid feed rate=32-45 ml/min; and O₂ supply rate 1.1777 L/min).

FIG. 14 is a chromatogram obtained from the conversion of lactose over a Pt/Al₂O₃ catalyst (T=150° C.; system pressure=85 psig; liquid feed rate=5-12 ml/min; and O₂ supply rate 1.1777 L/min).

FIG. 15 is a chromatogram obtained from the conversion of lactose over a Pt/Al₂O₃ catalyst (T=170° C.; system pressure=100.2 psig; liquid feed rate=15-28 ml/min; and O₂ supply rate=1.1777 L/min).

FIG. 16 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Mn/Ce catalyst at 170° C. and feed rates of 15-21 ml/min (Run 1), 13-22 ml/min (Run 2) and 21-31 ml/min (Run 3).

FIG. 17 is a chromatogram obtained from the conversion of lactose over a Mn/Ce catalyst (T=170° C.; back pressure=99.8-100.9 psig; liquid feed rate=15-21 ml/min; and O₂ supply rate=1.18 L/min).

FIG. 18 is a chromatogram obtained from the conversion of lactose over a Mn/Ce catalyst (T=170° C.; back pressure=98.1-100.7 psig; liquid feed rate=13-22 ml/min; and O₂ supply rate=1.18 L/min).

FIG. 19 is a chromatogram obtained from the conversion of lactose over a Mn/Ce catalyst (T=170° C.; back pressure=99.0-100.3 psig; liquid feed rate=21-31 ml/min; and O₂ supply rate=1.44 L/min).

FIG. 20 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pt/Mn—Ce catalyst at 170° C. and feed rates 20-25 ml/min (Run 1), 26-31 ml/min (Run 2) and 20-25 ml/min (Run 3).

FIG. 21 is a chromatogram obtained from the conversion of lactose over a Pt/Mn—Ce catalyst (T=170° C.; back pressure=99.9-100.7 psig; liquid feed rate=20-25 ml/min; and O₂ supply rate=1.18 L/min).

FIG. 22 is a chromatogram obtained from the conversion of lactose over a Pt/Mn—Ce catalyst (T=170° C.; back pressure=98.8-99.3 psig; liquid feed rate=26-31 ml/min; and oxygen supply rate=1.18 L/min).

FIG. 23 is a chromatogram obtained from the conversion of lactose over a Pt/Mn—Ce catalyst (T=170° C.; back pressure=99.9-99.4 psig; liquid feed rate=20-25 ml/min; and oxygen supply rate=1.44 L/min).

FIG. 24 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pt/Mn—Ce catalyst at 160° C. (Run 1), 150° C. (Run 2) and 140° C. (Run 3).

FIG. 25 is a plot of Ln(Reaction Rates) versus 1/T for the conversion of lactose over a Pt/Mn—Ce catalyst at 140° C., 150° C. and 160° C.

FIG. 26 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pd—Bi/C catalyst at O₂ supply rates of 1.18 L/min (Run 1), 0.156 L/min (Run 2) and 0.083 L/min (Run 3).

FIG. 27 is a plot of the concentration (mol/L) of lactobionic acid versus reaction time (min) for the conversion of lactose over a Pd—Bi/C catalyst at O₂ supply rates of 1.18 L/min (Run 1), 0.156 L/min (Run 2) and 0.083 L/min (Run 3).

FIG. 28 is a plot of the concentration (mol/L) of lactose versus reaction time (min) for the conversion of lactose over a Pd—Bi/C catalyst at liquid feed rates of 25-32 ml/min (Run 1), 14-18 ml/min (Run 2) and 30-34 ml/min (Run 3).

FIG. 29 is a plot of Ln(Reaction Rates) versus 1/T for the conversion of lactose over a Pd—Bi/C catalyst at 150° C. and 160° C.

Claims

1. A process for degrading lactose by catalytic wet oxidation, the process comprising: feeding oxygen gas and an aqueous solution of lactose to a reactor comprising a Pt/Al2O3 catalyst; andoxidizing the lactose in the reactor at elevated temperature and pressure to produce at least one of small organic acids, carbon dioxide, carbon monoxide, water and combinations thereof.

2. The process of claim 1 wherein the elevated temperature ranges from about 100° C. to about 170° C.

3. The process of claim 1 wherein the elevated pressure ranges from about 85 psig to about 100 psig.

4. The process of claim 1 wherein the molar ratio between oxygen gas and lactose in the reactor is at least about 12:1.

5. The process of claim 1 wherein the molar ratio between oxygen gas and lactose in the reactor is about 12:1.

6. The process of claim 1 wherein the oxidation of lactose produces small organic acids.

7. The process of claim 6 wherein the small organic acids comprise at least one of oxalic acid, tartaric acid, malic acid, succinic acid and combinations thereof.

8. The process of claim 6 further comprising feeding the small organic acids and oxygen gas into a reactor containing a Mn/Ce catalyst and oxidizing the small organic acids to water and at least one of carbon dioxide, carbon monoxide and combinations thereof.

9. A process for degrading lactose by catalytic wet oxidation, the process comprising: feeding oxygen gas and an aqueous solution of lactose to a reactor comprising a Mn/Ce catalyst; andoxidizing the lactose in the reactor at elevated temperature and pressure to produce water and at least one of carbon dioxide, carbon monoxide and combinations thereof.

10. The process of claim 9, wherein the elevated temperature ranges from about 100° C. to about 170° C.

11. The process of claim 9, wherein the elevated temperature ranges from about 140° C. to about 170° C.

12. The process of claim 9, wherein the elevated pressure ranges from about 85 psig to about 100 psig.

13. The process of claim 9 wherein the molar ratio between oxygen gas and lactose in the reactor is at least about 12:1.

14. The process of claim 13 wherein the molar ratio between oxygen gas and lactose in the reactor is about 12:1.

15. A process for degrading lactose by catalytic wet oxidation, the process comprising: feeding oxygen gas and an aqueous solution of lactose to a reactor comprising a Pt/Mn—Ce catalyst; andoxidizing the lactose in the reactor at elevated temperature and pressure to produce water and at least one of carbon dioxide, carbon monoxide and combinations thereof.

16. The process of claim 15, wherein the elevated temperature ranges from about 100° C. to about 170° C.

17. The process of claim 15, wherein the elevated temperature ranges from about 140° C. to about 170° C.

18. The process of claim 15, wherein the elevated pressure ranges from about 85 psig to about 100 psig.

19. The process of claim 15, wherein the molar ratio between oxygen gas and lactose in the reactor is at least about 12:1.

20. The process of claim 15, wherein the molar ratio between oxygen gas and lactose in the reactor is about 12:1.