Biomedical Engineering Reference
In-Depth Information
There are two types of base catalysts: homogenous and heterogeneous. Common
homogenous bases are sodium hydroxide (NaOH) and potassium hydroxide (KOH). The
amount of additional catalyst required to neutralize FFAs can be calculated according to
equations derived from [19] at a limit of 5% FFA:
NaOH [%FFA](0.144) + 1%
(8)
KOH [%FFA](0.197)/(purity) + 1%
(9)
Na(C
3
HO) [%FFA](0.190) + 0.25%
(10)
Heterogeneous Base Catalysts
Heterogeneous examples are alkali metal compounds like alumina and zeolites [21].
Solid bases are proposed to eliminate the need for water intensive washing to recover the
catalyst [24]. Some examples of solid base catalysts are CaO, KF, and Eu
2
O
3
on alumina or
silica and ferric ion doped hydrotalcite (HTC) precursors [24]. An important aspect of these
solid bases is high surface area. Table 5 compares surface areas of various heterogeneous
base catalysts.
Figure 7. Schematic structure of K/AP-MgO. K+ are located at the edge/corner and adjacent sites. All
particles are drawn to scale. [26]
