Banca de QUALIFICAÇÃO: ALYXANDRA CARLA DE MEDEIROS BATISTA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : ALYXANDRA CARLA DE MEDEIROS BATISTA
DATE: 07/12/2023
TIME: 14:00
LOCAL: videoconferência
TITLE:

Effect of the acetylation pretreatment process in microalgae biomass from thermocatalytic conversion using mesoporous materials.

KEY WORDS:

Monoraphidium sp.; Scenedesmus sp; Acetylation; Thermocatalytic study; Kinetic study; KIT-6

PAGES: 90
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Físico-Química
SPECIALTY: Cinética Química e Catálise
SUMMARY:

In recent decades there has been an increase in environmental awareness in mitigating atmospheric pollution and, with this, the search for alternative energy sources has emerged, among which microalgae biomass has stood out as a promising source of renewable and sustainable energy. This way, the main objective of the work is to evaluate pre-treatment processes applied to microalgae biomass based on physical-chemical analyzes and thermogravimetric analysis (TGA), then carry out the synthesis of catalytic materials that will be used in the thermocatalytic study and on the kinetics of biomass degradation. A kinetic study was carried out, based on thermogravimetric data obtained at heating rates of 10, 20, 30 and 40 °C/min, applying two free kinetic methods: Ozawa-Flynn-Wall (OFW) and Kissinger-Akahira-Sunose ( KAS) to calculate the values of activation energy for the degradation of microalgal biomass and to verify the activity of the catalytic materials. The species Monoraphidum sp. presented low humidity and low ash content compared to Scenedesmus sp. The micrographs made it possible to visualize the modification of the structure after the acetylation processes, confirmed by diffraction and infrared spectra, with characteristic bands of the process at 1742 cm-1  referring to the stretching of the carbonyl (C=O) of the ester, a band at 1372 cm-1 corresponds to the stretching of the C-H bonds of the methyl (CH3) of the acetyl group and the other around 1223 cm-1 characteristic of the C-O bond of the -O-(C=O)-CH3 group, confirming the esterification. The thermal behavior of biomass was evaluated based on thermal analysis (TGA) and its differential analysis (DTG), providing visualization of three mass loss events characteristic of microalgae, where the main event corresponds to the degradation of the majority constituents (carbohydrates, proteins and lipids) of the biomass, comparing the thermogravimetric data it was possible to observe that the second acetylation provided greater degradation and the Monoraphidium sp. showed greater decomposition than the Scenedesmus sp. sample. The pyrolysis of Monoraphidium sp. confirmed that the second acetylation provided greater bio-oil formation than the freeze-dried biomass and the sample with one acetylation, reaching a yield of 40 % for bio-oil, 52 % for biochar and 8 % for biogas. The catalytic support, KIT-6, and its impregnation with the metals Molybdenum (Mo) and Cobalt (Co) were successfully obtained and confirmed by X-Ray Diffraction (XRD), infrared spectra, as well as micrographs of the samples. Given the results obtained, the thermocatalytic study of Monoraphidum sp. acetylated twice pure and in the presence of the materials presented mass loss events compatible with those reported in the literature, as well as the catalyst activity was effective for the thermal degradation process of the main components of the biomass. Based on the values of the correlation coefficient (R2), it was verified that the KAS kinetic model is better suited to the thermocatalytic degradation process of microalgae. From the results of apparent activation energy (Ea), it was possible to verify that the use of the materials obtained provided an increase in this parameter, which can be justified by the occurrence of polymerization reactions. Therefore, it was possible to obtain important results on microalgae biomass with the purpose of carrying out thermocatalytic pyrolysis and characterizing the products obtained.

COMMITTEE MEMBERS:
Presidente - 2140818 - AMANDA DUARTE GONDIM
Externa ao Programa - 065.679.064-48 - ARUZZA MABEL DE MORAIS ARAUJO
Interno - 1645110 - CARLOS ALBERTO MARTINEZ HUITLE
Externa à Instituição - MARIA JOSE FONSECA COSTA - UFRN
Externo à Instituição - VINÍCIUS PATRÍCIO DA SILVA CALDEIRA - UERN