The materials of construction required for the main processing units in each of the four processes are summarized
in Table 1. Freedman et al. (1986) pointed out that alkali-catalyzed transesterification was less
corrosive to process equipment than the acid-catalyzed process. Davis et al. (2000) stated that, when the concentration
of sodium hydroxide is less than 50 wt.%, from ambient temperature to 95 C carbon steel could
be used. Peterson (1993) studied a batch process to produce biodiesel from rapeseed oil using 0.2 wt.% potassium
hydroxide, in which stainless steel was used for
the transesterification reactor.