Banca de QUALIFICAÇÃO: IGOR MATHEUS DE AMORIM SILVA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : IGOR MATHEUS DE AMORIM SILVA
DATE: 07/04/2026
TIME: 09:30
LOCAL: PLATAFORMA RNP
TITLE:

Development of SnO₂-based solutions in biorefinery processes: photocatalytic conversion of molecules derived from biomass. 

KEY WORDS:

heterogeneous photocatalysis; SnO₂; bimetallic materials; glycerol conversion; reactive oxygen species.

PAGES: 81
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUMMARY:

Biomass valorization has emerged in recent years as a promising strategy for the development of sustainable routes for the production of fuels and high value-added chemicals. In this context, glycerol, an abundant by-product of the biodiesel industry, presents great potential as a feedstock for catalytic and photocatalytic conversion processes. Among the different approaches investigated, heterogeneous photocatalysis stands out because it enables the use of light energy to promote selective oxidation reactions under mild conditions, such as ambient temperature and pressure. In this work, individual oxides and bimetallic materials based on tin dioxide (SnO₂) containing 5 wt.% of different metal ions were prepared in the form SnX5% (X = Ni, Cu, Ti). These materials were characterized in order to investigate their structural, electronic, and textural properties, and subsequently applied in the photocatalytic conversion of glycerol under visible light irradiation. The materials were synthesized by the coprecipitation method and characterized using several physicochemical techniques, including X-ray diffraction (XRD), UV–Vis diffuse reflectance spectroscopy (DRS), Fourier transform infrared spectroscopy (FTIR), temperature-programmed reduction (TPR), and N₂ physisorption analysis. The characterization results indicated the predominant formation of the rutile phase for pure SnO₂ and revealed that the incorporation of different metal ions into the tin oxide structural matrix promoted modifications in the structural, textural, and electronic properties of the materials, favoring the formation of structural defects and an increase in specific surface area. Photocatalytic tests for glycerol conversion showed that the bimetallic materials exhibited superior performance compared to pure SnO2, with particular emphasis on the SnTi5% system, which achieved glycerol conversion of up to 26% after 4 h of reaction. The reaction selectivity for the SnTi5% material led predominantly to the formation of glycolic acid and oxalic acid from glycerol. Product analysis for all materials indicated the formation of glyceraldehyde, tartronic acid, glycolic acid, and oxalic acid. The elucidation of the probable reaction mechanism suggests that the process occurs through different pathways involving (i) direct oxidation by photogenerated holes on the photocatalyst surface and (ii) indirect oxidation mediated by reactive oxygen species (ROS). The obtained results demonstrate that the structural modification of SnO2 by the insertion of metal ions can enhance photocatalytic activity and influence the reaction selectivity in glycerol conversion, contributing significantly to the development of new materials for photocatalytic biomass valorization.

COMMITTEE MEMBERS:
Externo(a) ao Programa - 1545506 - ANTONIO OSIMAR SOUSA DA SILVA - nullInterno(a) - 3182336 - EDEILDO FERREIRA DA SILVA JUNIOR
Interno(a) - 426640 - FABIANE CAXICO DE ABREU GALDINO
Externo(a) à Instituição - GEOVÂNIA CORDEIRO DE ASSIS - USP
Interno(a) - 1348288 - MARIO ROBERTO MENEGHETTI
Presidente - 1515173 - SIMONI MARGARETI PLENTZ MENEGHETTI