Utilização do catalisador de Rutênio (II) na reação de conversão do CO2 em HCOOH : um estudo computacional

Abstract

Carbon dioxide (CO2) is a compound related to the occurrence of the greenhouse effect. Hence, from the environmental point of view, the decrease of CO2 levels in the atmosphere is very important. Over the past decades, several techniques for reducing CO2 have been developed, showing that the conversion of CO2 to less harmful chemical species is an issue that has received much attention. However, all the conversion reactions have shown to have very high energy barriers, and thus, different inorganic catalyzers have been employed to address this issue. With this order to contribute to the reduction of CO2 that this work was done. In this work, molecular modeling was utilized for investigating the possibility of using a new catalyst containing [RuCl(H)2NO(PCH3)2]), in the reaction of conversion of CO2 to formic acid (HCOOH). The results indicate that the compound is promising as having catalytic activity (presenting a decrease in the determinant-setp energetic barrier up to 206,0 kJ.mol-1 , when compared to the non-catalyzed reaction). Hence, experimental studies with the referred compound are encouraged. In the reaction mechanism the catalyst presented two main steps, the heterolytic cleavage of the H2 molecule and the transfer of the hydride. Comparing different sets of base functions and change in the reaction cycle, we obtained an energy barrier of 128,95 kJ.mol-1 and 127,02 kJ.mol-1

in the two reaction cycles described by the set of functions of DGDZVP

bases, and an energy barrier of 112,83 kJ.mol-1

and 132,42 kJ.mol-1

in both reactions with the set of DGDZVP and 6-31+G(d,p) bases functions. The catalytic efficiency of the Ru catalyst is attributed to the ability of the metal to give, which significantly affects the heterolytic cleavage of the H2 molecule.