Aplicação de nanoparticulas de SnO2 e zeólitas em sensores para metano de mina de carvão

Abstract

Given that emissions control has become increasingly more rigorous, monitoring processes that require more precise and diversified information with regard to air pollution and toxic agents is inevitable. In the workplace, there is an increasing need for gas sensors with superior performance. Solid state sensors for gases are based on the fundamental principle that some metal oxide semiconductors such as SnO2 are very reactive on the surface where the analyte is adsorbed, changing the electric resistance of the oxide, which is in and of itself a reversible process, thus enabling the detection of gaseous species. This study presents test results obtained from the synthesis of nanostructured tin oxide by different methods until the production of the solid state sensor to monitor methane gas from coal mines. Zeolites were used to improve the selectivity of the sensor, as well as the validation of alternative flasks to collect gas samples. Regarding the characterization of SnO2, the analysis results of FESEM, TEM and XRD indicated nanometric structures. The gas adsorption tests on zeolite pellets showed that the zeolite 13X has a higher efficiency in adsorption of CO2 compared with other adsorbents, enabling its application as a filter for improving the selectivity of the sensor system. The AV_BR flasks were efficient when compared to commercial flasks for the collection and storage of CO, CO2 and CH4. The sensor was sensitive for CH4 at different concentrations and temperatures evaluated, mainly when doped with Pd (ER3B1 and ER3B2) and with smaller particle sizes (ER1A), as well as 13X pellets zeolite was efficient to make the sensor more selective to CH4 in the presence of CO2.