Banca de QUALIFICAÇÃO: SERGIO ANTONIO DE PAIVA ROCHA

Uma banca de QUALIFICAÇÃO de MESTRADO foi cadastrada pelo programa.
STUDENT : SERGIO ANTONIO DE PAIVA ROCHA
DATE: 21/10/2025
TIME: 09:00
LOCAL: NUPPRAR/LABPROBIO.
TITLE:

PYROLYSIS OF Desmodesmus sp MICROALGAE PRETREATED AND CATALYZED BY CO/Γ-AL₂O₃ AND MO/Γ-AL₂O₃ FOR THE PRODUCTION OF BIOPRODUCTS

 

KEY WORDS:

Microalgae, Acetylation, Mo/-Al 2 O 3 , Co/-Al 2 O 3 , Pyrolysis, Renewable hydrocarbons, Energy Transition.

 

PAGES: 180
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

The growing demand for sustainable energy alternatives has driven the
development of thermochemical pathways for biomass conversion. In this study,
we investigated the pyrolysis of the microalgae Desmodesmus sp. pretreated
with acetylation in the presence of Mo/γ-Al₂O₃ and Co/γ-Al₂O₃ catalysts, evaluating
the influence of the active metal and temperature on the distribution and
selectivity of the products formed. The microalgae were characterized by Fourier
transform infrared spectroscopy (FTIR) and thermogravimetric analysis
(TGA/DTG). Acetylation, performed three times, proved to be effective in
producing biomass suitable for pyrolysis, with low moisture (6.60%) and ash
(7.72%) contents and an increase in lipid content (49.56%). Molybdenum and
cobalt metals were impregnated into γ-Al₂O₃ by the wet impregnation technique
at a percentage of 10% and characterized by X-ray diffraction (XRD), Fourier
transform infrared spectroscopy (FTIR), acidity by desorption and
thermodesorption of n-butylamine, and scanning electron microscopy coupled to
an energy-dispersive spectrometer (SEM/EDS). The impregnation of the metals
was effective, without altering the structure of γ-Al₂O₃, with a percentage of
metals close to the target value of 12.45% for Mo and 11.21% for Co. The insertion of
Mo metal allowed acidity control favorable to pyrolysis reactions, with a total
acidity of 0.73 mmol/g. Pyrolysis tests, conducted at 300 °C and 500 °C, with and
without catalysts, and analyzed by Py-GC/MS, demonstrated that the
temperature change alone did not affect the products obtained. However, the
presence of catalysts significantly altered the composition of the products. The
best response occurred in the Mo/γ-Al₂O₃ catalyst combination at 500 °C with
high selectivity for propanoic acid, 2-hydroxy-2-methyl, and methyl ester, accounting for a concentration of 81.61%. The denitrogenating action was verified,
completely reducing the concentration, compared to 30.79% for thermal
pyrolysis. Regardless of the temperature and catalyst applied, the predominant
hydrocarbon fraction was kerosene, with the MAcMo500 test standing out with
99.28% of this fraction, followed by the MAcCo300 test (76.77%). The results
demonstrate the potential application of the microalgae Desmodesmus sp. in
biorefineries aimed at the production of advanced fuels and value-added
chemical inputs.

 

 

COMMITTEE MEMBERS:
Presidente - 2140818 - AMANDA DUARTE GONDIM
Interno - 350509 - ANTONIO SOUZA DE ARAUJO
Externa à Instituição - ARUZZA MABEL DE MORAIS ARAUJO - UFRN
Externo à Instituição - JOAO PAULO DA COSTA EVANGELISTA - UFRN