Study of Esterification Reactions in a Batch Reactor: - Rutgers ...
Study of Esterification Reactions in a Batch Reactor: - Rutgers ...
Study of Esterification Reactions in a Batch Reactor: - Rutgers ...
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<strong>Study</strong> <strong>of</strong> <strong>Esterification</strong> <strong>Reactions</strong> <strong>in</strong> a <strong>Batch</strong> <strong>Reactor</strong>:<br />
Model<strong>in</strong>g the Industrial Synthesis <strong>of</strong> Benzoic Acid and Biodiesel<br />
Chida Balaji Brett Lev<strong>in</strong>e Shir<strong>in</strong> Poustchi<br />
chidabalaji@gmail.com lev<strong>in</strong>e.brett@gmail.com spoustchi@msn.com<br />
Abstract<br />
This experiment exam<strong>in</strong>es two esterification reactions: the de-esterification <strong>of</strong><br />
ethyl benzoate <strong>in</strong>to benzoic acid and the transesterification <strong>of</strong> palm oil <strong>in</strong>to biodiesel.<br />
Through the de-esterification <strong>of</strong> ethyl benzoate, we mimicked the processes and<br />
experimental designs that are <strong>in</strong>volved <strong>in</strong> the production <strong>of</strong> API’s (active pharmaceutical<br />
<strong>in</strong>gredients). The transesterification <strong>of</strong> palm oil allowed us to observe the production <strong>of</strong><br />
biodiesel on a small scale. In a 1L batch reactor at 40 o C and 0.25 ethanol mole fraction,<br />
the rate constant was experimentally found to be 0.47 M -1 s -1 . This value is important <strong>in</strong><br />
that it tells us the rate (speed) <strong>of</strong> the reaction under the given conditions and compares<br />
favorably with the literature value <strong>of</strong> 0.51 M -1 s -1 [2]. For the biodiesel reaction, we<br />
successfully produced biodiesel <strong>in</strong> a 1L batch reactor with a percent yield <strong>of</strong> 23% at<br />
60 o C.<br />
Introduction<br />
The demand for pharmaceuticals<br />
is <strong>in</strong>creas<strong>in</strong>g; consequently, the need for<br />
efficient production designs is vital to<br />
the success <strong>of</strong> the pharmaceutical<br />
<strong>in</strong>dustry. By study<strong>in</strong>g the synthesis <strong>of</strong><br />
APIs, chemical eng<strong>in</strong>eers are striv<strong>in</strong>g to<br />
discover new ways to optimize the<br />
efficiency <strong>of</strong> these valuable reactions.<br />
Although API synthesis covers a<br />
multitude <strong>of</strong> chemical reaction types, our<br />
research focused on one specific reaction<br />
type: esterification.<br />
As with pharmaceuticals, the<br />
petroleum <strong>in</strong>dustry is constantly<br />
search<strong>in</strong>g for new ways to <strong>in</strong>crease their<br />
productivity. Additionally, these<br />
companies are actively pursu<strong>in</strong>g viable<br />
and renewable alternative energy sources<br />
as a result <strong>of</strong> the decreas<strong>in</strong>g fossil fuel<br />
reserves, which <strong>in</strong>clude w<strong>in</strong>d power,<br />
solar power, and the focus <strong>of</strong> our second<br />
experiment: biodiesel.<br />
<strong>Esterification</strong> reactions <strong>in</strong>volve<br />
either add<strong>in</strong>g (transesterification) or<br />
remov<strong>in</strong>g (de-esterification) an ester<br />
group to/from a molecule. Esters are a<br />
type <strong>of</strong> molecule formed from an organic<br />
acid and an alcohol and have the general<br />
structure <strong>of</strong> R-CO-OR’. Ester molecules<br />
exist <strong>in</strong> a variety <strong>of</strong> forms, rang<strong>in</strong>g from<br />
naturally occurr<strong>in</strong>g esters such as<br />
vegetable oils to commercially prepared<br />
products such as biodiesel.<br />
Commercially, esters are very<br />
prevalent and a valuable resource to<br />
many <strong>in</strong>dustries, especially the<br />
pharmaceutical <strong>in</strong>dustry. Many APIs, or<br />
active pharmaceutical <strong>in</strong>gredients, are<br />
formed <strong>in</strong> esterification reactions (ex.<br />
Aspir<strong>in</strong>). Without these qu<strong>in</strong>tessential<br />
<strong>in</strong>gredients, the medical and<br />
pharmaceutical <strong>in</strong>dustry would not be<br />
where it is today. Furthermore, it is <strong>of</strong><br />
great importance to cont<strong>in</strong>ue to study<br />
and understand how these esterification<br />
reactions work so eng<strong>in</strong>eers and other<br />
pr<strong>of</strong>essionals can cont<strong>in</strong>ue to produce<br />
products that will further benefit<br />
mank<strong>in</strong>d.<br />
Commercially, these reactions<br />
take place <strong>in</strong> very large batch reactors.
These specially designed vessels are<br />
<strong>of</strong>ten tailored to the reaction tak<strong>in</strong>g<br />
place, and provide a closed system that<br />
can <strong>of</strong>ten easily be controlled by a<br />
computer. These reactors also have the<br />
ability to control temperature, reactant<br />
concentrations, and many other th<strong>in</strong>gs<br />
such as pressure and pH depend<strong>in</strong>g on<br />
the specific reactor <strong>in</strong>volved. [1]<br />
Carefully analyz<strong>in</strong>g past experiments<br />
enables chemical eng<strong>in</strong>eers to make<br />
changes to the reactor conditions that<br />
would make the reactions more efficient<br />
and effective.<br />
Figure 1: The <strong>Batch</strong> <strong>Reactor</strong><br />
Above is a picture <strong>of</strong> the 1L batch reactor used <strong>in</strong><br />
both experiments. The outer layer <strong>of</strong> the reactor<br />
is a water jacket with a dedicated temperature<br />
probe that constantly monitors the reactor’s<br />
temperature.<br />
This paper analyzes two different<br />
esterification reactions. The first, the deesterification<br />
<strong>of</strong> ethyl benzoate <strong>in</strong>to<br />
benzoic acid, serves as a model for the<br />
synthesis <strong>of</strong> APIs <strong>in</strong> batch reactors. The<br />
second, the transesterification <strong>of</strong> palm<br />
oil <strong>in</strong>to biodiesel, <strong>of</strong>fers a source <strong>of</strong><br />
renewable and clean alternative energy.<br />
The purpose <strong>of</strong> both experiments is to<br />
simply study esterification reactions,<br />
both transesterification and deesterification,<br />
and how to conduct both<br />
experiments <strong>in</strong> a way that models their<br />
<strong>in</strong>dustrial production.<br />
There were two forms <strong>of</strong> objectives set<br />
to accomplish the goals <strong>of</strong> this project:<br />
the first be<strong>in</strong>g quantitative and the<br />
second be<strong>in</strong>g qualitative. The<br />
quantitative objectives <strong>of</strong> this research<br />
were:<br />
• Calculate the rate constant value,<br />
k, (ethyl benzoate reaction)<br />
• Calculate the % yield (biodiesel<br />
reaction)<br />
The qualitative objectives were:<br />
• Carry out a model deesterification<br />
reaction us<strong>in</strong>g ethyl<br />
benzoate<br />
• Carry out a model<br />
transesterification reaction us<strong>in</strong>g<br />
palm oil (to produce biodiesel)<br />
• Analyze the above small-scale<br />
reactions to serve as a model for<br />
<strong>in</strong>dustrial production<br />
The rate constant, k, describes how<br />
quickly the reaction proceeds (measured<br />
by the change <strong>in</strong> concentration <strong>of</strong> the<br />
reactants with respect to time). The<br />
percent yield is a measure <strong>of</strong> how much<br />
product was produced <strong>in</strong> relation to the<br />
predicted yield (from stoichiometry).<br />
Although both reactions were<br />
quantitatively analyzed, our study <strong>of</strong><br />
these reactions was mostly qualitative.<br />
The quantitative measures simply serve<br />
to gauge our accuracy <strong>in</strong> comparison to<br />
others who have completed similar<br />
experiments. This paper does not strive<br />
to f<strong>in</strong>d ways to maximize the efficiency <strong>of</strong><br />
these experiments; it simply strives to<br />
model the nature <strong>of</strong> esterification<br />
reactions.<br />
Background<br />
De-esterification <strong>of</strong> Ethyl Benzoate<br />
The first reaction <strong>in</strong>volved the deesterification<br />
<strong>of</strong> ethyl benzoate to<br />
benzoic acid. De-esterification reactions<br />
typically <strong>in</strong>volve hydrolysis, where
water cleaves a molecule (ethyl<br />
benzoate) <strong>in</strong>to its respective alcohol<br />
(ethanol) and acid (benzoic acid).<br />
Typically (and as with our experiment),<br />
these reactions take place with a basic<br />
catalyst (NaOH).<br />
Figure 2: Ethyl Benzoate Reaction [1]<br />
The product <strong>of</strong> this reaction,<br />
benzoic acid, has several important uses<br />
<strong>in</strong> consumer products. Benzoic acid is<br />
primarily used as a food/dr<strong>in</strong>k<br />
preservative and has been shown to<br />
<strong>in</strong>hibit the reproduction <strong>of</strong> mold and<br />
yeast molecules.<br />
As previously mentioned, this<br />
reaction serves as a model for the<br />
synthesis <strong>of</strong> APIs <strong>in</strong> a batch reactor<br />
similar to the one we used. In the<br />
chemical eng<strong>in</strong>eer<strong>in</strong>g world, measures<br />
such as yield (how much <strong>of</strong> the product<br />
is created compared to the theoretical<br />
yield) and speed are <strong>of</strong> great importance.<br />
Pharmaceutical companies want to be<br />
able to manufacture the APIs they need<br />
for their medic<strong>in</strong>e; however, they also<br />
want to make the reactions as efficient as<br />
possible.<br />
The speed and yield are<br />
<strong>in</strong>fluenced by a variety <strong>of</strong> conditions,<br />
ma<strong>in</strong>ly mole fraction (the relative<br />
composition <strong>of</strong> the reactant mixture) and<br />
temperature for the two reactions studied<br />
<strong>in</strong> this experiment. Most esterification<br />
reactions are reversible, which means<br />
that <strong>of</strong>ten the reactions are not complete<br />
(the actual yield is less than the<br />
theoretical yield). This is where<br />
chemical eng<strong>in</strong>eers use their knowledge<br />
and experience to optimize the reactions<br />
such that they yield that maximum<br />
amount <strong>of</strong> desired product <strong>in</strong> the<br />
smallest amount <strong>of</strong> time.<br />
The calculations for the biodiesel<br />
percent yield are relatively simple when<br />
compared to those for the ethyl benzoate<br />
reaction.<br />
The differential rate law for this<br />
reaction is:<br />
(Where EB represents Ethyl Benzoate)<br />
Equation 1: Differential Rate Law<br />
By tak<strong>in</strong>g the <strong>in</strong>tegral <strong>of</strong> both sides <strong>of</strong><br />
this equation, we obta<strong>in</strong> the <strong>in</strong>tegrated<br />
rate law, which is what we used <strong>in</strong> the<br />
experiment:<br />
Equation 2: Integrated Rate Law<br />
We also know that [EB] at time t is<br />
equal to the concentration <strong>of</strong> EB at t=0<br />
m<strong>in</strong>us the concentration <strong>of</strong> the acid used<br />
to quench it:<br />
Equation 3 (where BA represents Benzoic Acid)<br />
By substitution, we get:<br />
Equation 4<br />
Solv<strong>in</strong>g for k:<br />
Equation 5<br />
R = k[EB] 2<br />
[EB] = [EB]0<br />
1+[EB]0kt<br />
[BA] = [EB]0 – [EB]<br />
[EB]0 – [HCl] = [EB]0<br />
1+[EB]0kt<br />
k = [BA]<br />
[EB][EB]0t
This equation can be further simplified<br />
by:<br />
Equation 6<br />
k = [BA]<br />
([EB]0 – [BA])[EB]0t<br />
The above equations, most importantly<br />
the <strong>in</strong>tegrated rate law, allow us to<br />
calculate a value <strong>of</strong> ‘k’.<br />
Note that the [EB] = [OH]c <strong>in</strong> the<br />
orig<strong>in</strong>al mixture. Also note that this<br />
reaction is considered irreversible.<br />
Transesterification <strong>of</strong> Palm Oil<br />
While the de-esterification <strong>of</strong><br />
ethyl benzoate isn’t especially practical,<br />
the second experiment certa<strong>in</strong>ly is. As<br />
the world’s reliance on fossil fuels<br />
<strong>in</strong>crease and the supply <strong>of</strong> these energy<br />
sources deplete, there is an <strong>in</strong>creas<strong>in</strong>g<br />
necessity for an alternative and<br />
renewable energy source. Biodiesel, a<br />
blanket term for a combustible and<br />
energy rich hydrocarbon cha<strong>in</strong>, is<br />
produced by the esterification <strong>of</strong> palm<br />
oil (from palm trees) <strong>in</strong> the presence <strong>of</strong><br />
methanol and a catalyst.<br />
Figure 3: Biodiesel Reaction [6]<br />
The end result <strong>of</strong> the reaction is an<br />
immiscible mixture <strong>of</strong> biodiesel and<br />
other waste products <strong>in</strong>clud<strong>in</strong>g excess<br />
methanol and glycer<strong>in</strong>. These parts can<br />
be effectively separated to leave high<br />
purity biodiesel.<br />
Worldwide, biodiesel <strong>in</strong>terest is<br />
<strong>in</strong>creas<strong>in</strong>g due to the loom<strong>in</strong>g oil crisis.<br />
The results <strong>of</strong> this study <strong>of</strong>fer valuable<br />
<strong>in</strong>sight <strong>in</strong>to the production <strong>of</strong> biodiesel<br />
and <strong>in</strong>troduce it as a valuable and<br />
renewable alternative energy source.<br />
Method<br />
Both reactions, the deesterification<br />
and transesterification,<br />
took place <strong>in</strong> a 1L glass batch reactor.<br />
The reactor was surrounded by a water<br />
jacket, which allowed us to carefully<br />
regulate the temperature throughout the<br />
progression <strong>of</strong> both reactions. The<br />
reactor also had a temperature probe that<br />
recorded the temperature <strong>in</strong>side the<br />
reactor (a separate probe existed for the<br />
jacket), down to a tenth <strong>of</strong> a centigrade.<br />
Additionally, the reactor conta<strong>in</strong>ed an<br />
<strong>in</strong>ert stirrer on the bottom side which<br />
spun at a rate rang<strong>in</strong>g from 0-500<br />
revolutions per m<strong>in</strong>ute (rpm). With any<br />
reaction, a well-stirred reactor is needed<br />
to properly evaluate the rate constant.<br />
For the ethyl benzoate reaction,<br />
we calculated the rate constant first by<br />
cont<strong>in</strong>uously extract<strong>in</strong>g samples from<br />
the reactor. The composition <strong>of</strong> the<br />
samples was then analyzed us<strong>in</strong>g<br />
filtration. Based on previous<br />
experiments conducted by others on this<br />
same topic, it was determ<strong>in</strong>ed that this<br />
reaction was second order with respect<br />
to ethyl benzoate [2].<br />
To experimentally determ<strong>in</strong>e the<br />
rate constant, sampl<strong>in</strong>gs <strong>of</strong> the reactor<br />
mixture (which conta<strong>in</strong>ed a mixture <strong>of</strong><br />
ethyl benzoate, sodium hydroxide,<br />
ethanol, and benzoic acid) were taken at<br />
certa<strong>in</strong> <strong>in</strong>tervals <strong>of</strong> time. At specified<br />
times, we took a small ~10 mL sample<br />
<strong>of</strong> the reactant mixture from the<br />
sampl<strong>in</strong>g tray. Immediately after, we<br />
measured exactly 5.00 mL us<strong>in</strong>g a<br />
micropipette and added that to 5.00 mL<br />
<strong>of</strong> cold Hydrochloric acid. This<br />
important step is referred to as
quench<strong>in</strong>g, which means we used the<br />
HCl to effectively stop the reaction <strong>in</strong><br />
the sample that we took. As soon as the<br />
HCl was added, the time was recorded.<br />
After agitat<strong>in</strong>g the sample<br />
solution <strong>in</strong> a vortex, it was taken over to<br />
the titrator. The titrator used 0.10N<br />
sodium hydroxide to titrate the benzoic<br />
acid <strong>in</strong> the sample solution that was<br />
formed <strong>in</strong> the reaction.<br />
Figure 4: The Titrator<br />
Solver, an Excel application,<br />
compared the actual concentrations at<br />
each respective time to the theoretical<br />
concentrations as proposed by the<br />
second order rate law. Solver used the<br />
non-l<strong>in</strong>ear least squares regression test <strong>in</strong><br />
order to m<strong>in</strong>imize the sum <strong>of</strong> the squares<br />
<strong>of</strong> the errors to calculate ‘k’ [5].<br />
The experiment with the biodiesel<br />
<strong>in</strong>volved simply determ<strong>in</strong><strong>in</strong>g the percent<br />
yield, which compared the actual amount<br />
<strong>of</strong> biodiesel formed with respect to the<br />
amount dictated by stoichiometry [1].<br />
Ideally, we would have liked to study the<br />
k<strong>in</strong>etics <strong>of</strong> the biodiesel reaction;<br />
however, by us<strong>in</strong>g palm oil it is<br />
extremely impractical and difficult.<br />
Palm oil is a conglomerate <strong>of</strong> about five<br />
different hydrocarbons, which makes it<br />
nearly impossible to write a rate law<br />
(which is needed to calculate ‘k’).<br />
First, methanol and dry sodium<br />
hydroxide (NaOH) were added to the<br />
batch reactor such that they could be<br />
heated to the desired temperature before<br />
add<strong>in</strong>g the f<strong>in</strong>al <strong>in</strong>gredient: palm oil.<br />
Note that NaOH was added <strong>in</strong> pellet<br />
form <strong>in</strong>stead <strong>of</strong> solution form purposely<br />
to prevent any water from enter<strong>in</strong>g the<br />
reactor. When water is present, deesterification<br />
takes place via hydrolysis<br />
(and forms soap), which is exactly what<br />
we do not want to happen [1]. Once this<br />
temperature was reached, the palm oil<br />
was added and the reaction began.<br />
The follow<strong>in</strong>g day, we returned<br />
(with the assumption that the reaction<br />
was f<strong>in</strong>ished), and turned <strong>of</strong>f the stirrer.<br />
The hydrophilic and denser glycerol<br />
migrated to the bottom <strong>of</strong> the reactor<br />
while the less dense biodiesel rose to the<br />
top. Us<strong>in</strong>g a peristaltic pump, we slowly<br />
extracted the biodiesel layer <strong>in</strong>to an<br />
Erlenmeyer flask.<br />
Figure 5: Separation <strong>of</strong> Layers<br />
(Formation <strong>of</strong> Biodiesel)<br />
Next, we used a vacuum filtration<br />
system to filter out some <strong>of</strong> the glycerol<br />
waste products that collected <strong>in</strong> the<br />
<strong>in</strong>terphase <strong>of</strong> the mixture and thus were<br />
extracted <strong>in</strong>to our biodiesel mixture.<br />
The product <strong>of</strong> this filtration was then<br />
taken to the evaporator, which further<br />
purified the biodiesel by evaporat<strong>in</strong>g any<br />
methanol, glycerol, or other volatile<br />
products that were <strong>in</strong> the biodiesel<br />
solution. From here, the volume <strong>of</strong> the
iodiesel was taken and converted to a<br />
mass us<strong>in</strong>g the density <strong>of</strong> biodiesel and<br />
thus the yield was calculated.<br />
The<br />
processes we<br />
used <strong>in</strong> our<br />
experiments<br />
are ones that<br />
are utilized <strong>in</strong><br />
a much larger<br />
scale by<br />
<strong>in</strong>dustries.<br />
The batch<br />
reactors<br />
easily<br />
Figure 6: Evaporator<br />
allowed us to<br />
replicate the<br />
esterification reactions that are<br />
performed by large-scale <strong>in</strong>dustries. [1]<br />
One <strong>of</strong> our objectives was to analyze the<br />
reaction mechanisms for the deesterification<br />
<strong>of</strong> ethyl benzoate to<br />
benzoic acid. This was accomplished by<br />
evaluat<strong>in</strong>g the second-order rate<br />
constant, k, through analysis <strong>of</strong> the deesterification<br />
reaction. The rate<br />
constant, k, is affected by temperature,<br />
concentration <strong>of</strong> ethyl benzoate, and the<br />
ethanol mole fraction. Through the<br />
analysis <strong>of</strong> the reaction mechanisms <strong>of</strong><br />
the formation <strong>of</strong> benzoic acid we ga<strong>in</strong>ed<br />
<strong>in</strong>formation that we can apply to the<br />
production <strong>of</strong> different APIs.<br />
Results<br />
De-esterification <strong>of</strong> Ethyl Benzoate<br />
The concentrations <strong>of</strong> the ethyl benzoate<br />
experiment are shown below:<br />
Time(m<strong>in</strong>) [BA] [EB] Predicted<br />
0.00 0 0.1 0.1<br />
5.38 0.029 0.071 0.080<br />
16.23 0.059 0.041 0.057<br />
31.97 0.052 0.048 0.040<br />
44.90 0.056 0.044 0.032<br />
60.18 0.075 0.025 0.026<br />
81.15 0.072 0.028 0.021<br />
100.57 0.074 0.026 0.018<br />
Figure 7: Ethyl Benzoate Data<br />
Solver m<strong>in</strong>imized the difference <strong>of</strong> the<br />
squares between the actual and<br />
theoretical values to calculate a k value<br />
<strong>of</strong> 0.47 M -1s-1 . Aga<strong>in</strong>, ‘k’ describes how<br />
fast the concentration <strong>of</strong> the ethyl<br />
benzoate decreases with respect to time.<br />
Figure 8: EB concentration vs. time<br />
The above graph plots the concentration<br />
<strong>of</strong> the ethyl benzoate with respect to<br />
time. The solid l<strong>in</strong>e shows the expected<br />
concentration versus time accord<strong>in</strong>g to<br />
the second order <strong>in</strong>tegrated rate law.<br />
Transesterification <strong>of</strong> Palm Oil<br />
For the biodiesel reaction, the<br />
ma<strong>in</strong> <strong>in</strong>dicator was the percent yield.<br />
Accord<strong>in</strong>g to stoichiometry, 440 grams<br />
<strong>of</strong> biodiesel should have been produced<br />
given the <strong>in</strong>itial concentrations and<br />
volumes. In reality, we produced 92.8<br />
grams <strong>of</strong> biodiesel (115 mL) which
yields a density <strong>of</strong> 0.81 g/mL. The<br />
actual density <strong>of</strong> biodiesel ranges from<br />
0.86-0.90 g/mL.<br />
92.8g biodiesel 1 mL =115 mL biodiesel<br />
0.81 g<br />
%Yield=Experimental=92.8 g = 21.1%<br />
Predicted 440 g<br />
The above calculations show the<br />
determ<strong>in</strong>ation <strong>of</strong> mass <strong>of</strong> the biodiesel<br />
produced and its percent yield. Note that<br />
the density <strong>of</strong> biodiesel depends on the<br />
exact composition <strong>of</strong> the triglycerides<br />
used, which can not be determ<strong>in</strong>ed<br />
def<strong>in</strong>itively (the composition <strong>of</strong> the palm<br />
oil is only given <strong>in</strong> percentage ranges <strong>of</strong><br />
the triglycerides).<br />
Discussion/Conclusions<br />
For the de-esterification reaction, we<br />
obta<strong>in</strong>ed a rate constant <strong>of</strong> k=0.47 M -1 s -1<br />
at 40°C and 0.25 ethanol mole fraction.<br />
The rate constant was determ<strong>in</strong>ed<br />
through analysis <strong>of</strong> the decreas<strong>in</strong>g<br />
concentration <strong>of</strong> ethyl benzoate as the<br />
reaction progressed. The data that we<br />
gathered for the concentration <strong>of</strong> ethyl<br />
benzoate was slightly skewed from the<br />
predicted values because <strong>of</strong> problems<br />
with the experimental apparatus.<br />
Specifically, the micropipette, which is<br />
supposed to measure exact volumes, had<br />
a slight crack that was discovered upon<br />
completion <strong>of</strong> the experiment. This<br />
m<strong>in</strong>or fault prevented the necessary<br />
precision that we needed and thus is<br />
certa<strong>in</strong>ly a source <strong>of</strong> error.<br />
The ‘k’ value that we calculated<br />
corroborates with the literature value<br />
(0.51 M -1 s -1 ) at the same conditions and<br />
ethanol mole fraction [2]. This<br />
experiment provides a means for us to<br />
f<strong>in</strong>d ways by which to make the<br />
production <strong>of</strong> APIs more efficient. By<br />
calculat<strong>in</strong>g the rate constant at different<br />
temperatures and ethanol mole fractions<br />
we can obta<strong>in</strong> the fastest means to carry<br />
out the experiment. Faster processes &<br />
better experimental designs <strong>in</strong> the<br />
synthesis <strong>of</strong> APIs can help make the cost<br />
<strong>of</strong> essential drugs cheaper. Thus this<br />
research is applicable to pharmaceutical<br />
companies that strive to make cheaper<br />
drugs. The production <strong>of</strong> benzoic acid<br />
gave us an <strong>in</strong>sight <strong>in</strong>to the efficient<br />
synthesis <strong>of</strong> APIs as well as the<br />
mechanisms <strong>of</strong> a de-esterification<br />
reaction. This area <strong>of</strong> research and work<br />
is vital to the progress <strong>of</strong> pharmaceutical<br />
drugs and their effect on society.<br />
Biodiesel was the chief focus <strong>of</strong><br />
the second stage <strong>of</strong> our research.<br />
Biodiesel can be produced through many<br />
ways but the method we researched was<br />
the transesterification <strong>of</strong> palm oil.<br />
Through this experiment we tried to see<br />
if biodiesel could be produced <strong>in</strong> a<br />
productive way us<strong>in</strong>g the<br />
transesterification <strong>of</strong> vegetable oils. We<br />
used 500 grams <strong>of</strong> palm oil and mixed it<br />
with 450 mL <strong>of</strong> methanol and added 8.5<br />
grams <strong>of</strong> NaOH pellets.<br />
Although the reaction was<br />
<strong>in</strong>efficient, it is the most practical<br />
method <strong>of</strong> produc<strong>in</strong>g biodiesel for<br />
commercial use [3]. The <strong>in</strong>gredients for<br />
biodiesel production are relatively<br />
cheap, and thus biodiesel can become a<br />
viable alternative to more expensive<br />
gasol<strong>in</strong>e. Biodiesel has a lot <strong>of</strong> potential<br />
to become the primary fuel source <strong>of</strong> not<br />
just the nation but also the world [3].<br />
Additionally, biodiesel has a less <strong>of</strong> an<br />
environmental impact than conventional<br />
fuel sources. Biodiesel’s applications<br />
are grow<strong>in</strong>g from just vehicular use to<br />
domestic and <strong>in</strong>dustrial use. Research<br />
<strong>in</strong>to cheap and efficient synthesis <strong>of</strong><br />
biodiesel is pivotal to the resolution <strong>of</strong><br />
the world’s energy crisis [3].
On the contrary, our research<br />
with the biodiesel helped us identify the<br />
flaws <strong>of</strong> biodiesel and biodiesel<br />
production. Primarily, biodiesel has a<br />
relatively short shelf life and poor cold<br />
flow properties. Although the majority<br />
<strong>of</strong> it is liquid, biodiesel forms small solid<br />
clumps at room temperatures, which<br />
dim<strong>in</strong>ishes its ability to flow. Currently,<br />
research is be<strong>in</strong>g performed by chemical<br />
eng<strong>in</strong>eers to optimize the flow rate <strong>of</strong><br />
biodiesel by mix<strong>in</strong>g it with different<br />
solvents [4].<br />
Related Work<br />
Phillip Moseley and Mustafa Ohag<br />
published a paper <strong>in</strong> 1997 deal<strong>in</strong>g<br />
directly with the thermodynamic<br />
functions <strong>of</strong> the alkal<strong>in</strong>e hydrolysis <strong>of</strong><br />
ethyl benzoate <strong>in</strong>to benzoic acid.<br />
Moseley and Ohag performed the same<br />
experiment (the de-esterification <strong>of</strong> ethyl<br />
benzoate) we did over 70 times, with<br />
ethanol mole fractions rang<strong>in</strong>g from 0.1-<br />
0.9 and temperatures from 5-45<br />
centigrade at 5 degrees <strong>in</strong>tervals. A<br />
chart <strong>of</strong> their results is <strong>in</strong>cluded below:<br />
Figure 9: Rate constant values for<br />
Moseley’s experiment [2]<br />
This graph shows the rate constants, k,<br />
throughout different ethanol mole<br />
fractions (x-axis) and temperatures. As<br />
a general trend, the rate constant<br />
decreases with <strong>in</strong>creas<strong>in</strong>g ethanol mole<br />
fraction and <strong>in</strong>creases with <strong>in</strong>creas<strong>in</strong>g<br />
temperature. Additionally, vary<strong>in</strong>g the<br />
ethanol mole fraction has a more<br />
pronounced effect at lower temperatures<br />
(it is almost negligible at relatively high<br />
temperatures).<br />
Due to time constra<strong>in</strong>ts, we only<br />
performed one experiment with the ethyl<br />
benzoate (0.25 mole fraction, 40 o C). We<br />
gauged our accuracy by compar<strong>in</strong>g our<br />
experimental rate constant to the one<br />
Moseley and Ohag calculated for the<br />
same temperature and mole fraction.<br />
For the biodiesel production<br />
experiment, we referred to a previous<br />
paper published by Invensys Foxboro, an<br />
eng<strong>in</strong>eer<strong>in</strong>g firm specializ<strong>in</strong>g <strong>in</strong><br />
commercial automation <strong>in</strong> terms <strong>of</strong><br />
production and manufactur<strong>in</strong>g systems.<br />
The paper outl<strong>in</strong>es the different<br />
ways that biodiesel is manufactured,<br />
provid<strong>in</strong>g the follow<strong>in</strong>g useful chart<br />
which details a generic<br />
transesterification reaction to produce<br />
biodiesel:<br />
Chart 2: Biodiesel production flowchart<br />
[3]
Note that biodiesel production is a<br />
relatively cyclic process <strong>in</strong> that many <strong>of</strong><br />
the byproducts can be<br />
reprocessed/recycled back <strong>in</strong>to the<br />
reaction. Consequently, this is one <strong>of</strong><br />
the ma<strong>in</strong> reasons that biodiesel is a<br />
feasible alternative energy source.<br />
Future Work<br />
Be<strong>in</strong>g that our research project covered<br />
such a current issue (especially with the<br />
biodiesel reaction), there exists myriad<br />
possibilities for future work. The<br />
world’s oil reserves will only cont<strong>in</strong>ue to<br />
deplete, thus exacerbat<strong>in</strong>g the already<br />
prevalent oil crisis. Additionally, the<br />
world’s reliance on oil products has<br />
severe environmental implications.<br />
We could implement Moseley’s<br />
design for his ethyl benzoate experiment<br />
<strong>in</strong>to our biodiesel experiment by us<strong>in</strong>g<br />
different <strong>in</strong>itial mole fractions and<br />
temperatures to measure the percent<br />
yield. This experiment would show<br />
under which conditions the production<br />
<strong>of</strong> biodiesel is most efficient.<br />
As with any experiment,<br />
repetition breeds more accuracy and<br />
precision. Because <strong>of</strong> time constra<strong>in</strong>ts,<br />
we were only able to run the ethyl<br />
benzoate and biodiesel reaction once<br />
each. In the future, it would be<br />
beneficial to run each experiment aga<strong>in</strong><br />
at the same conditions and furthermore<br />
at different conditions. These<br />
experiments would add validity to the<br />
experiment and <strong>of</strong>fer a wider scope <strong>of</strong><br />
analysis on both reactions.<br />
Acknowledgements<br />
We would like to thank the follow<strong>in</strong>g<br />
people without whom this experiment<br />
would not have been able to take place.<br />
First, the New Jersey Governor’s School<br />
Board <strong>of</strong> Overseers for allow<strong>in</strong>g the<br />
Governor’s School <strong>of</strong> Eng<strong>in</strong>eer<strong>in</strong>g and<br />
Technology to take place. Second, we<br />
would like to thank <strong>Rutgers</strong> University<br />
and Dean Don Brown. Next, we would<br />
like to thank Blase Ur, Program<br />
Coord<strong>in</strong>ator, for not only arrang<strong>in</strong>g this<br />
research project, but also for plann<strong>in</strong>g<br />
this entire program, which has truly been<br />
an <strong>in</strong>valuable experience. Additionally,<br />
we thank Dr. Henrik Pedersen, Chemical<br />
Eng<strong>in</strong>eer<strong>in</strong>g Department Chair, for his<br />
everyday guidance and breadth <strong>of</strong><br />
knowledge as our primary project<br />
advisor. We also thank Patrick Nwaoko,<br />
our counselor advisor for his assistance<br />
throughout this entire experience. Most<br />
importantly, we’d like to thank the<br />
follow<strong>in</strong>g program sponsors who<br />
susta<strong>in</strong>ed this Governor’s School<br />
program <strong>in</strong> a f<strong>in</strong>ancially difficult year:<br />
Prudential, Morgan Stanley, <strong>Rutgers</strong><br />
University, the John and Margaret Post<br />
Foundation, and John and Laura<br />
Overdeck. We f<strong>in</strong>ally thank the entire<br />
Governor’s School staff for their<br />
friendship and guidance regard<strong>in</strong>g not<br />
only this research project but also the<br />
program as a whole.
References<br />
[1] – Pedersen, Henrik. The <strong>Batch</strong> <strong>Reactor</strong>.<br />
[2] – Moseley, Phillip, and Mustafa Ohag. "Thermodynamic functions <strong>of</strong> activation <strong>of</strong><br />
the alkal<strong>in</strong>e hydrolysis <strong>of</strong> ethyl benzoate and <strong>of</strong> ethyl p-nitrobenzoate <strong>in</strong><br />
ethanol–water mixtures <strong>of</strong> various compositions at different temperatures."<br />
(1997).<br />
[3] – "Guide to Instrumentation for Biodiesel Fuel Production." Invensys Foxboro<br />
[4] – Lev<strong>in</strong>e, Brett. "<strong>Batch</strong> <strong>Reactor</strong>." E-mail to Michael Boczon. 15 July 2008.<br />
[5] – Harris, Daniel C. "Nonl<strong>in</strong>ear Least-Squares Curve Fitt<strong>in</strong>g with Micros<strong>of</strong>t Excel<br />
Solver." Computer Bullet<strong>in</strong> Board. 15 July 2008<br />
.<br />
[6] - http://en.wikipedia.org/wiki/Image:Generic_Biodiesel_Reaction1.gif