Open AccessA novel acid catalyst based on super/subcritical CO 2 -enriched water for the efficient esterification of rosin
Author(s) -
Dan Zhou,
Linlin Wang,
Xiaopeng Chen,
Xiaojie Wei,
Jiezhen Liang,
Dong Zhang,
Guoxin Ding
Publication year - 2018
Publication title -
royal society open science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.84
H-Index - 51
ISSN - 2054-5703
DOI - 10.1098/rsos.171031
Subject(s) - rosin , catalysis , business , chemical engineering , chemistry , environmental science , pulp and paper industry , organic chemistry , engineering , resin acid
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 CO 2 –enriched high temperature liquid water (HTLW) as a green acid catalyst in the esterification reaction of rosin with glycerol was investigated. The pH of CO 2 –H 2 O 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 CO 2 pressure, a rosin-to-glycerol molar ratio of 1.32 and 269°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 CO 2 -enriched HTLW catalyst can decrease the activation energy and significantly accelerate the reaction rate.