Procedimento analítico para recuperação do enxofre elementar do carvão de Candiota / RS

Abstract

Currently, there is a vast intensification around the generation of energy in a cleaner way, causing an increase in research on different types of coal conversion, including hydropyrolysis. This process occurs through the thermochemical conversion of organic material and water, generating gaseous products, combustible liquid hydrocarbons and solid fraction. Coal currently represents an available alternative, especially in Rio Grande do Sul, but it is little explored in the national scenario, being used almost entirely for the generation of electricity, through combustion. However, in recent years there has been a growing concern with the emissions of sulfur compounds through this process, as it poses a risk to both the environment and the population, mainly due to the pyritic sulfur present in coal, which converts into hydrogen sulfide (H2S) and sulphate sulfur (SO4 2- ). With these prerogatives, the present work had as objective the desulfurization of the gaseous stream, coming from the hydropyrolysis and containing H2S, through chemical absorption in a solution of cupric chloride (CuCl2). The experiments were carried out at the Laboratório de Energia e Carboquímica (LEC), at UNIPAMPA on the campus Bagé, using mineral coal from the Candiota-RS. The gas generated in the hydropyrolysis was submitted to the absorption process with a chemical reaction between H2S and CuCl2 and the formed precipitate was analyzed by FT-IR and identified as copper sulfide (CuS). Then, it was subjected to chemical reaction, using concentrated nitric acid (HNO3), to obtain sulfur, characterized by FT-IR. The sulfur recovery efficiency was 21,95% and 48,60%. The FT-IR results showed, for the hydropyrolysis gas, the presence of H2S in the range above 3600 cm-1 , for the precipitate formed during absorption, CuS was identified in the range of 989 cm-1 and sulfur synthesized, showed peaks in the band from 426 cm-1 to 927 cm-1 .