Banca de DEFESA: POLIANA PINHEIRO DA SILVA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : POLIANA PINHEIRO DA SILVA
DATE: 10/07/2023
TIME: 16:00
LOCAL: Videochamada online
TITLE:

USE OF GREEN COCONUT SHELL POWDER FOR THE PRODUCTION OF LEVULINIC COMPOUNDS

KEY WORDS:

thermogravimetry, levulinic acid, levulinates, biomass conversion, biofuels.

PAGES: 113
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Tecnologia Química
SPECIALTY: Tratamentos e Aproveitamento de Rejeitos
SUMMARY:

Agro-industrial residues are most often widely disposed of in landfills or in an uncontrolled manner. An environmentally friendly alternative can be the use of this residual biomass for the production of sustainable chemicals with high added value. Levulinic acid and its derivatives are examples of these products, which have high added value and can serve as precursors for various industrial products and also used as fuel additives. The thesis study is divided into three main stages that aim to study the feasibility of converting coconut husk powder into levulinic acid. The first determined the biomass composition before and after esterification through thermal analysis; there was a reduction in the amounts of cellulose (18.18% to 9.77%) and hemicellulose (44.65% to 26.18%) after the reaction. Then, the degradation kinetics of the coconut husk powder was carried out using the Ozawa–Flynn–Wall method, which demonstrated that the activation energy is directly related to the presence of hemicellulose and cellulose, increasing from 143 kJ.mol- 1 for 125 kJ.mol-1. The second stage consisted of the synthesis of levulinic acid generated from the powder of green coconut shell. The reactions took place in a Parr Instruments stainless steel reactor, with a capacity of 300 mL, and the samples were analyzed on HPLC. The reaction conditions were determined according to a factorial design with the addition of 3 points, temperature, time and amount of catalyst being the three significant. The response variable was the yield of levulinic acid, which reached a maximum of 42.94% in the central conditions (190 ºC, 2h, 1:0.25). The third study comprised a three-factor Box-Behnken (PBB) design, with the response being the conversion of levulinic acid into ethyl levulinate. The highest conversion occurred in 1hrs, molar ratio (levulinic acid: ethanol) 4:1 and catalyst concentration 0.04mol/L. Then, a comparison was made between the synthesis of methyl and ethyl levulinate, where it was noticed that the only significant factor in both reactions was time.

COMMITTEE MEMBERS:
Presidente - 1308273 - EDUARDO LINS DE BARROS NETO
Interno - 1670497 - HUMBERTO NEVES MAIA DE OLIVEIRA
Externo ao Programa - 1566922 - LINDEMBERG DE JESUS NOGUEIRA DUARTE - UFRNExterna à Instituição - LEONETE CRISTINA DE ARAUJO FERREIRA MEDEIROS SILVA - UFERSA
Externa à Instituição - PAULA FABIANE PINHEIRO DO NASCIMENTO - UFRN