期刊
ROYAL SOCIETY OPEN SCIENCE
卷 5, 期 7, 页码 -出版社
ROYAL SOC
DOI: 10.1098/rsos.171031
关键词
super/subcritical CO2-H2O; green catalytic esterification; rosin; kinetics; thermodynamics
资金
- National Natural Science Foundation of China [31560241]
- Guangxi Natural Science Foundation [2014GXNSFDA118010]
- Key Laboratory of Petrochemical Resource Processing and Process Intensification Technology [2016Z02]
Rosin esters are widely applied as masticatory substances and beverage stabilizers, while classical acid-catalysed processes will lead to metal residue or environmental issues. Super/subcritical CO2-enriched high temperature liquid water (HTLW) as a green acid catalyst in the esterification reaction of rosin with glycerol was investigated. The pH of CO2-H2O binary system, as calculated based on gas-liquid equilibrium, charge balance and chemical equilibrium equations, ranged from 3.49 to 3.70 depending on the reaction conditions, indicating effective acid catalysis. Response surface methodology experiments showed the optimum conditions were 3.5 h, 3.9 MPa CO2 pressure, a rosin-to-glycerol molar ratio of 1.32 and 269 degrees C, and an enhanced esterification yield of 94.74% was achieved, which was superior to that obtained using a ZnO catalyst. It was found that the esterification kinetics was a pseudo first-order reaction, and the enthalpy and entropy of activation were calculated using the Arrhenius-Polanyi equation. The presence of super/subcritical CO2-enriched HTLW catalyst can decrease the activation energy and significantly accelerate the reaction rate.
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