catalysts are commonly used in the transesterification process of biodiesel
production. Some of these catalysts involve sodium hydroxide (NaOH), potassium
hydroxide (KOH), sodium methoxide (NaOCH3), potassium methoxide
(KOCH3) and sodium ethoxide (NaOCH2CH3). These
catalysts are used due to its ability to catalyze reactions at low reaction
temperatures, atmospheric pressures and gives higher conversions in shorter
Sodium methoxide and
potassium methoxide are better catalysts than sodium hydroxide and potassium
hydroxide because of its ability to dissociate into CH3O-
& Na+ and CH3O- and K+
respectively when compared to biodiesel yields.
However, based on current
research and previous experiments done, it has found that NaOH and KOH are
mostly used in biodiesel production. “The highest biodiesel yield produced by Calophyllum inophyllum was reported by
Silitonga et al. (2014) with 98.53% by using 1 wt% KOH and 9:1 methanol to oil
ratio. Silva, Camargo, and Ferreira (2011) reported 95% of biodiesel yield from
soybean oil by using NaOH with 1.3 wt% catalyst loading and ethanol to oil
ratio of 9:1.” ~ Talha, N. S. & Sulaiman, S. (2016). OVERVIEW OF CATALYSTS IN BIODIESEL PRODUCTION,
11 (1, January 2016).
Homogeneous Acid Catalyst
catalysts are known to be a better choice when the feedstock contains a higher
quantity of free fatty acids (FFAs). This is because
FFAs can’t be converted to biodiesel with the use of alkaline catalysts.
Commonly used acid catalysts in the transesterification process of biodiesel
production involve sulfuric acid and
hydrochloric acid. Despite its ability to overcome the FFA in the feedstock,
this type of catalyst has a relatively slower reaction rate.
Therefore, when using this
catalyst, the alcohol to oil molar ratio is the
main factor that manipulates the reaction. Adding excess alcohol speeds
up the reaction and favor the biodiesel production.
“In a study of
acid-catalyzed transesterification of sunflower oil using HCl, Sagiroglu et al.
(2011) reported 95.2% of biodiesel yield with 100?C reaction temperature and
1.85 wt% catalyst loading. Cao et al. (2013) used H2SO4
in the acid-catalyzed transesterification with 0.5 wt% catalyst loading
reported 92.5% biodiesel yield from Chlorella
pyrenoidosa.” ~ Talha, N. S. & Sulaiman, S. (2016). OVERVIEW OF CATALYSTS IN BIODIESEL PRODUCTION,
11 (1, January 2016).