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IMPROVEMENT OF MICROWAVE-ASSISTED CATALYTIC DECOMPOSITION
REACTIONS IN NON-ABSORBING MEDIA

Jovan Mitić

Supervisor: Prof. Dr Borivoj Adnađević, Faculty of Physical Chemistry, University of Belgrade
Regional Centre for Talented Youth Belgrade II, Belgrade, Joxy97@yahoo.com

1. Introduction increase of 18.68% was achieved. The linear
correlation between inserted absorbent’s mass and
Microwave (MW) radiation is a type of absorption percentage was found. The experiment
electromagnetic radiation with wavelengths ranging with zeolite A showed that the MW absorption
from 1 m to 1 mm and frequencies from 0.3 GHz up percentage is constant while the total amount of
to 300 GHz. Unlike pretermission and reflection, absorbed power increases linearly with linear
MW absorption heats up matter which is used in increase of microwave power. Having applied these
organic chemistry for achieving more efficient results on biodiesel synthesis, 100% of epholene-28
reactions. Some of them require high temperatures was converted in biodiesel at 300 W power in 15 min
but take place in a weak MW absorbing solvent. and temperatures over 280°C.
The goal of this project was to find a way to
efficiently warm up a non-absorbing media in MW 4. Conclusions
by changing system’s dielectric properties instead of
increasing the energy consumption. Graphite has shown the highest microwave
absorption capability. Changes in absorption
2. Materials and Methods percentage linearly correspond to absorbent’s mass
changes. Absorption percentage also stays the same
Seven different MW absorbents were chosen based at different MW powers, while total amount of
on previous research [2] and their availability: absorbed power changes linearly. As small
Zeolite A, Al, SiC, MnO 2, V 2O 5, CuO and graphite. percentage of graphite can absorb a significant
They were tested under the same conditions. Volume amount of MW energy for a short period of time, it
3
of 9 cm of motor oil was used as non-absorbing has a huge practical value when it comes to energy
media. Added absorbent’s mass was 1% of oil mass. and time preservation. this means that some
All samples were exposed to a MW radiation of processes with high potential in dealing with
50 W power and 5 min of hold time. CEM Discovery environmental problems, such as converting a plastic
device was used as MW source and temperature waste into a biodiesel in microwave media, are now
sensor. Measurements were done three times along becoming practically possible and efficient. this was
with usage of magnetic stirrer. Changes in absorption shown through an efficient biodiesel synthesis. The
percentage were tested at linear oil’s mass changes of study has shown a new method high scientific and
0.5% and 0.25% of oil’s mass. Absorbing efficiency practical value in organic chemistry and
of zeolite A (biodiesel synthesis catalyst) was tested environmental protection.
at MW power changes. Concept application was
tested on biodiesel synthesis from epholene-28 (low- 5. References:
density polyethylene) in motor oil.
[1] Stuerga, Didier, Microwave-material interactions
3. Results and Discussion and dielectric properties, key ingredients for mastery
of chemical microwave processes. Wiley-vch, 2006.
In this study graphite’s absorption percentage was
significantly higher than percentage of all the other [2] Chen, Lin Feng, et al. Microwave electronics:
tested substances. It is due to graphite’s high relative measurement and materials characterization. John
dielectric permittivity. The ratio of relative dielectric Wiley & Sons, 2004. APA
permittivity among substances is consistent with
experimental ratio of absorbing percentage. Pure
motor oil absorbed 1.59 of MW, while the system
with 1% of graphite absorbed 20.28%, which means
that scientifically high MW absorption percentage