Banca de DEFESA: ANTONY JEOVA TEIXEIRA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : ANTONY JEOVA TEIXEIRA DA SILVA
DATA : 27/03/2025
HORA: 08:00
LOCAL: https://cnrs.zoom.us/j/98668821669?pwd=HFUUyeNUdhX9aScrDQPznDXpEHTWvy.1
TÍTULO:

DEVELOPMENT OF BETA ZEOLITES INCORPORATED WITH ZIRCONIUM FOR THE RECOVERY OF GLYCEROL

PALAVRAS-CHAVES:

Glycerol dehydration; acetol; Lewis acidity; Zr-beta; pre-crystallization.

PÁGINAS: 106
GRANDE ÁREA: Outra
ÁREA: Ciências Ambientais
RESUMO:

Studies have been carried out to add value to glycerol from biodiesel. The catalytic dehydration reaction of glycerol has been highlighted for promoting products with higher added value. The use of zeolites is a promising strategy due to their properties such as high specific area, acidity and shape selectivity. Thus, the work aims to develop beta zeolites with the presence of Zr and evaluate their catalytic activity in the dehydration reaction of glycerol. The standard hydrothermal synthesis of Zr-beta was carried out with 18 days in a hydrofluoric medium at the Si/Zr ratio = 200. The adapted methodology was carried out using Si/Zr ratios of 200 and 25, with 2 days of pre-crystallization and different days of crystallization: 5, 10 and 18 days. The materials were characterized by XRD, TG, N2 adsorption and desorption, SEM-EDS and pyridine acidity. The dehydration reaction was carried out for 4 h and the aliquots were analyzed by chromatography. The catalyst with the best performance underwent a 10 h reaction test. XRD confirmed the production of beta zeolite with incorporated Zr, both in the standard and adapted synthesis, except for the synthesis with 18 days and Si/Zr = 25. TG demonstrated the thermal stability of the materials at temperatures above 300ºC. The N2 adsorption and desorption of the materials presented a type I isotherm typical of microporous materials. The sample with 18 days pre-crystallized presented a specific area (610 m2/g) close to the standard sample (617 m2/g). The samples with the ratio of 25 showed high adsorbed volume at high relative pressures and specific area of 315 and 475 m2/g for the 5-day and 10-day samples, respectively. The micrographs of the zeolites showed large crystals in the range of 3 to 17 micrometers, as well as possibly silica particles for the syntheses with the Si/Zr ratios = 25, which suggest a dissolution of the zeolite during the crystallization. The EDS showed that the insertion of zirconium was efficient due to its good distribution. The samples with Si/Zr 25 showed a higher concentration of Lewis sites due to the adsorption of pyridine. The catalysts showed high conversion of glycerol, especially the standard zeolite, with 74% conversion in 4 h of reaction, as well as selectivity for acetaldehyde, acrolein and acetol. This same zeolite was stable in the test for 10 h and its selectivity alternated between acetaldehyde and acetol throughout the conversion time, proving to be a selective material that is more resistant to coke, promising for obtaining products of greater economic interest.

MEMBROS DA BANCA:
Externo à Instituição - ALEXANDER SACHSE
Presidente - 7961 - ANNE GABRIELLA DIAS SANTOS CALDEIRA
Interno - 13136 - LEANDRO BEZERRA DE LIMA
Externa à Instituição - LINDIANE BIESEKI - UFRN
Externo à Instituição - THIAGO PINHEIRO BRAGA - UFRN