Page 355 - Refining Biomass Residues for Sustainable Energy and Bioproducts

322 Refining Biomass Residues for Sustainable Energy and Bioproducts

better output of LA produced in subsequent reaction as compared to biomass feed
without separation (Ramli and Amin, 2014). The pretreatment has shown a signifi-
cant improvement toward the LA concentration yield as compared to raw biomass.
For example, the pretreatment of empty fruit bunch (EFB) and kenaf by using
[EMIM][Cl] ionic liquid shows high LA yield of 31.6% and 39.5%, respectively, as
compare to raw EFB and kenaf only produced 23.4% and 27.9%, respectively
(Ramli et al., 2014b). As focused in this chapter, the ozone pretreatment of OPF
also shows significant result as 14.3% of LA yield was obtained pretreated OPF as
compared to 2.5% of LA yield from raw OPF (without pretreatment) (Wan Omar
and Amin, 2016). The reaction was conducted at 180 C for 1 h to obtain high LA

yield from OPF biomass by applied H 2 SO 4 as catalyst. Based on the results, the
ozone pretreatment has shown high efficiency on LA production by utilizing pre-
treated OPF. The approach of ozone pretreatment on the biomass as future green
alternative has shown its potential.
Basedonthe previous work,the pretreated biomass usually applied homoge-
neous acid catalyst such as H 2 SO 4 for hydrolysis to obtain high LA yield (Chin
et al., 2015; Ramli et al., 2014b; Lopes et al., 2017). H 2 SO 4 hydrolysis of pre-
treated biomass to LA required short time of reaction (,1 h) as compared to other
catalysts used. The acid hydrolysis of ionic liquid pretreated OPF via H 2 SO 4 has
provided higher LA yield of 39.5% at short reaction of 44 min (Ramlietal.,
2014b). Similar to pretreated oak (Jeong et al., 2017) and sugarcane bagasse
(Lopes et al., 2017) which gives high LA yield at lower reaction time of 0.17 h
and 1.25 h, respectively, via H 2 SO 4 hydrolysis. However, the usage of H 2 SO 4 as
catalyst should be considered by substituting with heterogeneous catalyst for
future alternative. Currently, the heterogeneous catalysts were used as one-pot
reaction of biomass to LA without pretreatment (Ya’aini et al., 2012; Ramli and
Amin, 2015). One-pot reaction of the heterogenous catalyst may provide high LA
yield at long reaction time or vice versa. The combination of the effective and
less toxic pretreatment method such as ball milling, ionic liquid, and ozone with
the heterogeneous catalyst for hydrolysis could improve the overall reaction pro-
cess. For example, the pretreated OPF using [BMIM][Br] which has been utilized
for acid hydrolysis by using Fe/HY zeolite has produced high LA yield of 25.3%
(Ramli et al., 2014a). Metal salts supported catalyst can be applied as heteroge-
neous catalyst for the LA production from biomass as shown by the previous Fe/
HY zeolite (Ramli and Amin, 2015) and Cr/HY zeolite (Ya’ainietal.,2012)cata-
lyst. Based on Tiong and Yap (Tiong et al., 2018), the efficiencies of various
metal salts on the LA yield can be summarized by following its reactivity as
ZnCl 2 . CrCl 3 . FeCl 3 . This metal can be applied on suitable support to enhance
the catalyst activity for biomass hydrolysis to LA.

14.3.4 Potential biochemical synthesis
The previous subsections describe chemicals that have been successfully synthe-
sized from ozone-treated lignocellulosic biomass. There are still many rooms for
exploration in this field, and the ozonolysis pretreatment method is an emerging