Banca de DEFESA: CAROLINA DA SILVA COSTA

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : CAROLINA DA SILVA COSTA
DATE: 10/04/2025
TIME: 03:08
LOCAL: Virtual
TITLE:

Solvent-Free Hydrogenation of Succinic Acid and γ-Butyrolactone: A Sustainable Approach for Obtaining High-Value-Added Products

KEY WORDS:

Selective Hydrogenation, 1,4-Butanediol, Tetrahydrofuran, Continuous-Flow system, Pellets, Supercritical CO2 and Green Processes.

PAGES: 160
BIG AREA: Engenharias
AREA: Engenharia Química
SUBÁREA: Operações Industriais e Equipamentos para Engenharia Química
SPECIALTY: Operações de Separação e Mistura
SUMMARY:

Gamma-butyrolactone (GBL) and succinic acid (SUC) are building-blocks molecules widely used in the production of high-value-added compounds. Therefore, the present study aimed to evaluate the hydrogenation of these compounds in sustainable, solvent-free media, using supercritical carbon dioxide (scCO₂) conditions, with the use of micro- and macroscopic (pellet) catalytic forms of PdRe/SiO₂. The study was divided into three articles. The first article primarily aimed to evaluate the effect of solvent-free reactions with the addition of scCO₂ as a reaction medium for the hydrogenation of GBL in batch systems. The same conditions were applied to the hydrogenation of SUC in batch systems, evaluating the effect of temperature, H₂ pressure, catalyst mass, and Re content in the catalyst. In the third article, technical catalysts in the form of PdRe/SiO₂ pellets were developed to study solvent-free hydrogenation of GBL in continuous flow systems. Pellets with different thermal treatments (uncalcined and calcined at 300 and 500 °C) were evaluated and compared with powdered catalysts in batch systems. In fixed-bed reactors, the effect of temperature, pressure, GBL and H₂ flow rates, and bed height was evaluated. The results demonstrated that the reaction medium had a significant impact on the selectivity of GBL hydrogenation, acting as a modulating factor for selectivity. In solvent-free conditions, 93% selectivity for tetrahydrofuran (THF) was obtained. With the addition of scCO₂ (80 bar), the selectivity was completely shifted to 1,4-butanediol (BDO), achieving 100%. For SUC, the most severe conditions of temperature (280 °C), pressure (90 bar), and catalyst mass (50 mg) resulted in 75.3% selectivity for THF. In GBL continuous flow reactions, excellent results were achieved with pellets calcined at 300 °C due to their high surface area. Under 175 °C, 50 bar H₂, 0.1 mL/min GBL flow rate, 0.7 mL/min H₂ flow rate and 7 cm of the bed, 52% GBL conversion and 86% selectivity for BDO were achieved. Overall, the results obtained in this work demonstrate the effectiveness of solvent-free approaches and the versatility of scCO₂ as a selectivity regulator, highlighting the potential of these systems in green and sustainable processes with unprecedented selectivities for THF and BDO. Furthermore, the study suggests the development of technical catalysts for scale-up applications.

COMMITTEE MEMBERS:
Presidente - 1543286 - CAMILA GAMBINI PEREIRA COURTIAL
Interna - 1979301 - RENATA MARTINS BRAGA
Externa ao Programa - 1415657 - ANDREA OLIVEIRA NUNES - UFRNExterna à Instituição - FABÍOLA CORREIA DE CARVALHO
Externo à Instituição - PAULO FILHO MARQUES DE OLIVEIRA - USP
Externo à Instituição - PEDRO MIGUEL VIDINHA GOMES - USP