Page 149 - Biofuels Refining and Performance

132 Chapter Four

methanolysis of beef tallow in 15 min [170]. Some authors have found
that absolute ethanol produced higher conversion and less viscosity
than absolute methanol at 50 C, after 2 h [171]. Nebel and Mittelbach
have found n-hexane was the most suitable solvent for extraction of fat
from meat and bone meal. The extracted material was converted into
fatty acid methyl esters through a two-step process [172]. Lee et al.
have performed a three-step transesterification to produce biodiesel
from lard and restaurant grease. They found that a porous substance,
such as silica gel, improved the conversion when more than 1 M methanol
was used as reaction substrate [173]. Mbaraka et al. also synthesized
propylsulfonic acid-functionalized mesoporous silica materials for
methanol esterification of the FFA in beef tallow, as a pretreatment step
for alkyl ester production [174].
Engine tests also showed a reduction in emission, except oxides of
nitrogen that increased up to 11% for the yellow grease methyl ester
[157]. Cold-flow properties of the fat-based fuels were found to be less
desirable than those of soy-based biodiesel, with comparable lubricity and
oxidative stability [175]. To solve this problem, Kazancev et al. blended
up to 25% of pork lard methyl esters with other oil methyl esters and
fossil diesel fuels. In this case, the CFPP showed a value of 5 C. In
winter, only up to 5% of esters can be added to the fuel. Depressant
Viscoplex 10-35 with an optimal dose of 5000 mg/kg was found to be the
most effective additive to improve the cold properties [101].

4.6 Future Lines

Research in most of the nonedible oil crops previously mentioned has
been insufficient. To determine the viability of their use as a source of
biodiesel and to optimize the transesterification as well as engine per-
formance, more research is needed. But, there are also other nonedible
and low-cost edible oily crops and trees that could be exploited for
biodiesel production. Amongst them, allanblackia, bitter almond, chaul-
moogra, papaya, sal, tung, and ucuuba produce oils that hold immense
potential to be used as a raw material for producing biodiesel. Most of
them grow in underdeveloped and developing countries, where govern-
ments may consider providing support to the activities related to col-
lection of seeds, production of oil, production of biodiesel, and its
utilization for cleaner environment. Hence, to facilitate its integration,
a legal framework should be legislated to enforce regulations on
biodiesel. Biodiesel should be seriously considered as a potential source
of energy, particularly in underdeveloped and developing countries with
very tight foreign exchange positions and insufficient availability of
traditional fuels.