Levulinic acid (LA) is one of biomass derived building block chemicals with various applications. Catalytic esterification
of LA with alkyl alcohol produces levulinate ester which can be applied as fragrance, flavouring agents, as well as fuel
additives. In this study, a series of sulfated silica (SiO2
) catalyst was prepared by modification of SiO2
with sulfuric acid
(H2
SO4
) at different concentrations; 0.5 M to 5 M H2
SO4
. The catalysts were characterized, and tested for esterification
of LA with ethanol to ethyl levulinate (EL). The effect of various reaction parameters including reaction time, catalyst
loading and molar ratio of LA to ethanol on esterification of LA to EL were inspected. The catalyst with high concentration
of acid sites seemed suitable for LA esterification to EL. Among the sulfated SiO2
catalysts tested (0.5 M-SiO2
, 1 M-SiO2
,
3 M-SiO2
and 5 M-SiO2
), 3 M-SiO2
exhibited the highest performance with the optimum EL yield of 54% for reaction
conducted at reflux temperature for 4 h, 30% 3 M-SiO2
loading and LA to ethanol molar ratio of 1:20. Besides, the
reusability of 3 M-SiO2
catalyst for LA esterification with ethanol was examined for five cycles. Esterification of LA with
methanol and 1-butanol were also carried out for methyl levulinate (ML) and butyl levulinate (BL) productions with 69%
and 40% of ML and BL yields, respectively. This study demonstrates the potential of sulfated SiO2
catalyst for levulinate
ester production from LA at mild process condition.