Table 3. Catalytic Conversion of Glycerol to Lactic Acid Using Pt/ZrO2 Catalysts Calcined at Different Temperaturesa.
| Selectivity
in the conversion of glycerol (%) |
Yield in the conversion of cyclohexene
(%)b |
|||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Entry | Catalyst | Conv.GLY (%) | YLA (%) | S(transfer-H) (%) | Lactic acid | Glyceric acid | Glycolic acid | Propanediol | Cyclohexane | Benzene |
| 1 | 2Pt/ZrO2 400-R250 | 46 | 46 | 35 | 99 | 0.3 | 0.0 | 0.8 | 8.1 | 0 |
| 2 | 2Pt/ZrO2 550-R250 | 96 | 95 | 36 | 99 | 0.5 | 0.2 | 0.7 | 17 | 0 |
| 3 | 2Pt/ZrO2 800-R250 | 24 | 23 | 0.9 | 98 | 0.3 | 0.0 | 1.9 | 0.1 | 0 |
| 4 | 2Pt/ZrO2 800-R400 | 12 | 10 | 0 | 87 | 0.7 | 0.7 | 11 | 0 | 0 |
a
Reaction conditions: aqueous glycerol solution: 10 mmol (0.5 M, 20 mL); cyclohexene: 20 mmol; nominal Pt/glycerol ratio = 1/1950; NaOH: 15 mmol; temperature: 160 °C; reaction time: 4.5 h; N2 pressure: 20 bar.
b
Under the employed reaction conditions (molglycerol:molcyclohexene = 1:2) the maximum theoretical yield of cyclohexane is 50%.