Avaliação de catalisadores heterogêneos obtidos a partir das cascas do ovo, para síntese de biodiesel
The gradual growth of energy consumption in the world has been linked to concerns about the depletion of energy sources and the environmental imbalance due to the predatory use of natural resources. In the world, only 9% of the energy consumed comes from renewable sources. Given this high global...
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| Materyal Türü: | doctoralThesis |
| Dil: | pt_BR |
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Brasil
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| Online Erişim: | https://repositorio.ufrn.br/jspui/handle/123456789/27575 |
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| Özet: | The gradual growth of energy consumption in the world has been linked to
concerns about the depletion of energy sources and the environmental imbalance due to the
predatory use of natural resources. In the world, only 9% of the energy consumed comes from
renewable sources. Given this high global dependence on non-renewable energies, research is
needed to develop new sources of alternative energy. Biodiesel, a biofuel used for diesel cycle
engines, is proving to be one of the viable alternatives to this current problem. It also has, in
some aspects, advantages over petroleum diesel, such as: non-toxic, renewable,
environmentally friendly and relatively biodegradable, as well as reducing (during the
combustion process) emissions of polluting gases, such as: carbon particles, carbon
monoxide, sulfur oxides and polycyclic aromatic hydrocarbons. Biodiesel is usually obtained
through transesterification, in which one mole of triacylglycerides reacts with three moles of
alcohol (methanol or ethanol) to form three moles of biodiesel and one mole of glycerin. The
reaction is usually catalyzed by a strong homogeneous base, NaOH or KOH. However, the
use of homogeneous catalysts results in soap formation, separation difficulty and effluent
generation. Due to these limitations, the need arose to study heterogeneous catalysts to obtain
biodiesel. The CaO is a heterogeneous catalyst that stands out for the high catalytic and
readily available capacity. However, the catalytic results of these solids are highly dependent
on the preparation method as well as on the reaction conditions employed. Therefore, the
objective of the research is to develop and evaluate several heterogeneous catalysts obtained
from the shell of the calcined egg, for the production of soybean biodiesel via methyl. To
obtain the different CaO samples, three raw materials (white and brown eggshell and
commercial CaCO3) calcined at different temperature (800°C, 900°C and 1000°C) and time
conditions (80, 120 and 160 minutes) over a heating rate of 5°C min-1
.Totaling 27 samples.
The best result among the eggshells was the white sample calcined at 800ºC in 160 minutes
(CB8P16). The CaO has a disadvantage, since it undergoes hydration and carbonatation
reactions very easily, forming respectively Ca(OH)2 and CaCO3. However, even after the
majority formation of CaCO3, the properties and characteristics present are maintained, as a
strong base and presence of active sites on the surface, which characterize as a solid catalytic
potential for transesterification reaction. Another reason for the maintenance of the catalytic
capacity is in the formation of Ca(OCH3)2, obtained from the initial mixture between
methanol and CaO, which presents more catalytic characteristics than CaO causes a process
called CaO activation. The calcined mixture between the CaO derived from the eggshell of
the chicken egg and the diatomite, formed the wollastonite, which presents a better catalytic
performance than the CaO under some reaction conditions. |
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