Produção de hidrogênio a partir do ácido fórmico catalisada por complexos organometálicos de rutênio contendo iminopiridinas

Abstract

This study explored the production of molecular hydrogen (H₂) through the catalytic decomposition of formic acid (AF) using ruthenium (II) organometallic compounds as precatalysts. The main goal was to develop an efficient process for hydrogen generation, analyzing the influence of various N-N ligands, quantifying hydrogen production, and determining the kinetic and thermodynamic activation parameters of the reactions. Results revealed that the Amp complex exhibited the highest catalytic efficiency, characterized by elevated turnover frequencies (TOF) and conversion rates, particularly at higher temperatures. In contrast, bulky substituents, as in the Tbump complex, reduced catalytic activity due to substrate approach inhibition. Kinetic and thermodynamic studies based on Arrhenius and Eyring models indicated that the Amp complex had a higher activation energy (72.68 kJ mol⁻¹) but superior catalytic efficiency at elevated temperatures, while Diipmp displayed intermediate performance. The influence of water in the reaction medium was tested only for the Amp complex, resulting in lower catalytic efficiency. The Diemp complex, evaluated exclusively at 90°C, showed promising performance with high TOF values, highlighting its potential under specific conditions. In conclusion, formic acid decomposition with ruthenium catalysts is a feasible approach for hydrogen production, with the Amp complex standing out. This study provides a foundation for future research, particularly on the use of the Diemp complex under varying conditions.