More wt.% yields. However, increasing the catalyst amount

More than 90% yield of
FAME can be achieved at the methanol-to-oil molar ratio of 18:1. This result
clearly shows that the increase in the methanol amount drives the reaction
equilibrium towards the product side. However, there was no significant
increase in the FAME yield and oil conversion with the
further increasing amount of methanol. This is
probably due to excess of alcohol could
increase the solubility of glycerol and the presence of
glycerol in the reaction mixture could drive the reaction equilibrium backward the reverse direction, hence lowering the
reaction conversion.

 

Effect of the catalyst
amount

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To study the effect of
catalyst amount, methanol-to-oil molar ratio of 18:1 at 65°C
was fixed and the transesterification of palm oil and methanol was carried. But
the amount of catalyst was varied from 1wt % –
6
wt % of C. inophyllum oil used. The figure shows that with increasing the amount of catalyst FAME
yield as well as the oil conversion was also remarkably increased. It was found
that the maximum FAME yield of 92% occurred when the catalyst amount was at 4 wt.%
yields.  However, increasing the catalyst
amount beyond 4 wt % produced no change in the oil conversion as well as the
FAME yield. This is mainly due to the limitation imposed by the reaction equilibrium;
with more catalyst only the reaction speed be increase not the reaction
conversion and the product yield 31. In fact, it can be observed that with further increasing
the catalyst amount beyond 5 wt.%, oil conversion and FAME yield were slightly
decreased. This is probably due to the presence of higher amount of catalyst
increases viscosity of the reaction mixture and results in the poor diffusion
between the three-phase (methanol-oil-catalyst) systems 31, 32.

 

4.2.1.3 TEMPERATURE OF THE PROCESS:

The temperature of trans-esterification process
was done at 50°C, 60°C, 70°C and
80°C.

Effect of the reaction
temperature and time in order to study the FAME yield, transesterification
reaction of palm oil with methanol was done by using the methanol-to-oil molar
ratio of 18:1 and 4 wt.%
catalyst. Fig. 6 shows that the FAME rapidly reaches a high
percent yield at high reaction temperatures. For example, at 50°C the FAME
yield was 49 %, whereas at 60°C the FAME yield
could reach above 72 % within 3h of reaction time. As the reaction mixture is
the three-phase (methanol-oil-catalyst) system, thus the reaction can be
retarded by the diffusion resistance between different phases. Increasing the
reaction temperature could decrease viscosity of the reaction mixture,
enhancing the miscibility of methanol and oil as well as the diffusion of both
reactants in the miscible liquid phase 34, and
hence increasing the reaction rate. Moreover, it was found that the maximum FAME
yield can be achieved at 70°C and further increasing of reaction temperature to
80°C leads to the decrease in the FAME yield. This is mainly due to the fact
that methanol was evaporated and remained in the vapor phase inside the reactor
causing a decrease in the concentration of methanol.

 

RE-USABILITY TEST:

Further studies were carried out on the
re-usability of the residual ash as a catalyst for biodiesel production
process. The repeated usage of the ash as a catalyst is an important criterion
as well as economical and prevents environmental degradation due to disposal.
The study was carried out by tranesterifying the Calophyllum inophyllum oil at the optimum conditions for 3 h. After
the process is completed, the ash is separated and washed several times with
distilled water. The ash is then dried. The dried ash is again employed for
another cycle of transesterification process of the
Calophyllum inophyllum oil at the optimized conditions.

 

Under the optimum
transesterification conditions of 4 wt.%
catalyst loading, Catalyst reusability was tested. 1:18 oil to methanol molar
ratio, temperature-, 70°C, reaction time of 3h and stirring speed of 700rpm.
After each cycle, the spent catalyst was regenerated using methanol washing followed
by drying. As shown in Fig. 6, the
yield was lowered to 75.2 %, in
the tenth cycle. The decrease in
yield could be ascribed to catalyst deterioration due to poisoning by glycerol
and soap present in the reaction mixture. Deactivation of active sites is also
caused due to the dissolution of Ca from CaO to the alcoholic phase. The
presence of calcium glyceroxide in the spent catalyst could possibly be a
factor in its reduced reusability as reported by ——-. 43.
The combination of CaO and glycerol gives rise to the formation of Calcium
glyceroxide 43. in the consequent cycles as there was low
catalytic performance, the yield could possibly be increased with the using
large amount  of catalyst loading and
longer reaction time. Although ideally a catalyst should be reused as many
times as possible, the limited number of reusability cycles with waste residual
ash is compensated by the fact that residual ash is a waste product.

Thus one can conclude that the residual ash
from sugarcane leaf can act as an effective catalyst for tranesterification of Calophyllum
inophyllum oil and can be used as a catalyst for more than one cycle

 

CONCLUSION:

 

Renewable source of energy has gained utmost
importance for the following reasons, the increasing consumption of natural
fossil fuels, the increasing population growth, the increasing global warming
and environmental pollution. Many researchers are working to identify cheap and
renewable source of energy to replace the conventional fuel. Biodiesel is one
of the important renewable energy and biodiesel is used in many parts of the
world to replace the petroleum diesel. Biodiesel is produced by the
tranesterification process using alkali or acid catalyst.