2.6.2 Alcohol precipitation to remove salts and esterification
of acetic and butyric acid with methanol
The concentrated broth was mixed with anhydrous methanol at a mass ratio
of 1: 2.5, and the pH of the mixture was adjusted to 2 by adding 37%
HCl solution. After standing still overnight, the precipitated inorganic
salts were removed by centrifugation, and the methanol solution was fed
to a similar reaction system as described in Section 2.5 for the
esterification of acetic and butyric acid, except that the volume of the
round-bottomed flask was 2 L. The reaction was carried out at
70oC, with an Amberlyst-15 loading of 10% (w/w) for
2.5 h. The mixture was filtered to separate the methanol solution from
the used catalyst after the reaction was finished. Subsequently,
methanol, MA and MB were together separated from the esterified broth at
the heating temperature of 60oC and the vacuum
pressure of 200 mbar in a rotary evaporator.