Production of bifunctional calcium oxide catalyst supported
on gamma alumina for the production of biofuel from the
transesterification of crambe oil
1st Paulo Sergio Theodoro,1,* 2nd Pedro Augusto Arroyo,1 3rd Edson Antonio da Silva2
1 State
University of Maringá, Maringá, 87021-980, Brasil
University of Western Paraná, 85903-000, Brasil
*Corresponding author: [email protected]
2 State
Keywords: Heterogeneous catalysis, basic sites, acid sites, renewable, energy.
1. Introduction
The development of studies and new technologies
aimed at the production of energy from renewable
sources plays an important role in the contemporary
world. Currently energy consumption is linked to the
environment because much of the energy consumed
in the world comes from nonrenewable sources and
that compromise the environmental quality
throughout the planet earth. In this way it is
necessary to search for alternative sources in order
to replace fossil fuels. In this context, the production
of biofuel is included, with vegetable oils as a
renewable source. Processing of vegetable oil with
short chain alcohol such as ethanol, through the
esterification reaction of fatty acids and
transesterification of the triglycerides, yields the
ethical ethers known as biodiesel. The production of
the biodiesel that presents less generation of residual
load and less aggression to the environment is the
ethyl route via heterogeneous catalysis. Thus much
research should be directed to produce catalysts that
perform well in esterification and transesterification
reactions of vegetable oils in order to maximize
biodiesel production to meet the high demand for
renewable energy.
Many oxides are used as catalysts in the synthesis of
biodiesel, among them the use of metallic oxides and
also metallic oxides supported1,2.
Calcium oxide (CaO) is one of the alkali metal
oxides that has a strong basic characteristic due to
the binding to the conjugated oxygen anion3. The
high basic strength of the CaO surface sites is
responsible for the excellent adsorbent property and
catalytic activity of this oxide. Therefore, calcium
oxide has been used as a catalyst in various chemical
reactions, among them the transesterification
reaction of vegetable oils for the production of
biofuels 4.
Among the transition alumina to γ-alumina is
highlighted in many studies, because of its important
application as active phase or as catalytic support 5.
The use of γ-alumina (γ-Al2O3) as support in the
heterogeneous catalysis is possible because it
presents properties as thermal stability and high
specific area, which promotes the high dispersion of
active phases6. According to 6, the aluminum ions
and some hydroxyls produce acidic sites on the
surface of γ-Al2O3. Thus the production of catalysts
in which calcium oxide is supported on γ-alumina
(CaO / γ-Al2O3) can result in bifunctional catalysts
carrying active sites with acidic and basic properties.
Thus the present work aims to the synthesis and
chemical characterization of a bifunctional catalyst
from the solid oxide dispersion using calcium with
support to γ-Al2O3 and evaluation of the catalytic
potential in the transesterification reaction of crambe
oil.
Crambe oil is rich in erucic acid which makes it
unfit for human consumption. Its production is of
short period around ninety days and the seed
presents 37% of oil content the plant adapts very
well several types of climate 7–9.
2. Experimental Part or Theoretical Details
Solid calcium oxide (CaO) was added to the γ-Al2O3
in amounts of sufficient mass up to 10%. After this
addition over γ-Al2O3 the mixture was kept under
manual agitation for 30 minutes, then the heat
treatment in the furnace was started at 600 oC for 4
hours and with a ramp of 5 oC min-1. TPD (NH3 e
CO2) analysis was performed using the
Quantachrome Instruments model Chembet-3000
equipment.
For FT-IR determinations, it was used in the Fourier
Transform Infrared Spectrophotometer (FT-IR),
Frontier model (Perkin Elmer) using the attenuated
total reflectance (ATR) technique.
Transesterification reaction
The transesterification reactions employing soybean
oil were performed in duplicate in a closed reactor
with magnetic stirring at 150 °C, molar ratio of oil /
ethanol = 1:10, 1450 rpm, 10% (w/w) catalyst to
mass oil, reaction time 6 h.
3. Results and discussion
Figure 1 shows the FT-IR spectra of the γ-Al2O3
support and the 5% CaO/γ-Al2O3 catalyst.
Comparing the spectra, the formation of a band by
the molecular vibration of the CaO-H bond in the
catalyst spectrum in the 1400 cm-1 region is
observed.
Figure 2. TPD curve (CO2) of the catalyst
10%CaO/γ-Al2O3
Table 2Concentração e classificação dos sítios ácidos
Peak
1°
2°
Total
concentration of
the sites (mmolg-1)
0,1296
0,5941
Temp. (oC)
325
600
Site strength
Moderate
Strong
0,7238
4. Conclusions
In the transesterification reaction of cramb oil, the
average yield of ethyl ester obtained was 84%. This
result showed that the 10%CaO/Al2O3 catalyst of
bifunctional character presented an excellent
performance in the reaction of biofuels.
References
(1)
spectrum of γ-Al2O3 (a) and
catalyst 10% CaO/γ-Al2O3 (b)
Figure 1. FT-IR
Figures 2 and 3 show the programmed temperature
desorption curves TPD (NH3) and TPD (CO2) of the
10% CaO / γ-Al2O3 catalyst.
Table 1 and Table 2 present the concentration values
and classification of acidic sites and basic sites
present on the catalytic surface.
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
Figure 1. Ammonia desorption curve at programmed
temperature TPD (NH3) of the catalyst 10%CaO/γAl2O3
Table 1 Concentration and classification of acidic sites
Peak
1°
2°
Total
concentration of
the sites (mmolg-1)
0,320
0,736
1,055
Temp. (oC)
420
470
Site strength
Strong
Strong
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