Estudo de compostos sulfurados em cimento asfáltico de petróleo por espectrometria de massas de altíssima resolução ESI(+) FT-ICR MS e espectroscopia de RMN de ¹³C

Abstract

The characterization of sulfur compounds in asphalt petroleum cement (PAC) is essential to understand the aging processes that occur in this matrix, since such compounds participate in the oxidation reactions in these processes. In order to characterize the sulfur compounds in PACwe used positive-ion mode electrospray Fourier transform ion cyclotron resonance massspectrometry (ESI(+)FT-ICR MS)associated with solid-phase extraction (SPE),and 13Cnuclear magnetic resonance (13C NMR). Three PAC samples were submitted to SPE separation where the reactive (sulfide), non-reactive (thiophene) and mercaptan fractions were extracted, generating a total of ninefractions (threefractions for each PAC). The fractions, the original PACs and their maltenes were methylated and analysed by the ESI(+)FT-ICR MS technique.The PACs and their maltenes werealsoanalysed by 13C NMR before and after methylation, and the results were compared.ESI(+) FT-ICRionization process of the sulfur fractions produced by the SPE technique was much more efficient in relation to its original samples, and it was possible to detect organosulfur with a greater amplitude of average molecular mass distribution. Through ESI(+) FT-ICR and 13C NMRseveral types of sulfur compounds have been detected, such as sulfides, disulfides, thiophenes and dibenzothiophenes. Finally, the chemical profile of PACs sulfur compounds was correlated with some of their physicochemical properties likeviscosity and softeningpoint