Samples of Ba1-xSrxCe0.9Y0.1O3-δ, 0 < x < 0.1, with Improved Chemical Stability in CO2-H2 Gas-Involving Atmospheres as Potential Electrolytes for a Proton Ceramic Fuel Cell.

Comparative studies were performed on variations in the ABO3 perovskite structure, chemical stability in a CO2-H2 gas atmosphere, and electrical conductivity measurements in air, hydrogen, and humidity-involving gas atmospheres of monophase orthorhombic Ba1-xSrxCe0.9Y0.1O3-δ samples, where 0 < x < 0.1. The substitution of strontium with barium resulting in Ba1-xSrxCe0.9Y0.1O3-δ led to an increase in the specific free volume and global instability index when compared to BaCe0.9Y0.1O3-δ. Reductions in the tolerance factor and cell volume were found with increases in the value of x in Ba1-xSrxCe0.9Y0.1O3-δ. Based on the thermogravimetric studies performed for Ba1-xSrxCe0.9Y0.1O3-δ, where 0 < x < 0.1, it was found that modified samples of this type exhibited superior chemical resistance in a CO2 gas atmosphere when compared to BaCe0.9Y0.1O3-δ. The application of broadband impedance spectroscopy enabled the determination of the bulk and grain boundary conductivity of Ba1-xSrxCe0.9Y0.1O3-δ samples within the temperature range 25-730 °C. It was found that Ba0.98Sr0.02Ce0.9Y0.1O3-δ exhibited a slightly higher grain interior and grain boundary conductivity when compared to BaCe0.9Y0.1O3-δ. The Ba0.95Sr0.05Ce0.9Y0.1O3-δ sample also exhibited improved electrical conductivity in hydrogen gas atmospheres or atmospheres involving humidity. The greater chemical resistance of Ba1-xSrxCe0.9Y0.1O3-δ, where x = 0.02 or 0.05, in a CO2 gas atmosphere is desirable for application in proton ceramic fuel cells supplied by rich hydrogen processing gases.

Assessment of mercury emissions into the atmosphere from the combustion of hard coal in a home heating boiler.

The purpose of the paper was to determine the factor of mercury emission into the atmosphere by households in Poland. Research for a home coal-fired boiler typical of Polish conditions was carried out, which was conducted throughout the heating season. On the basis of assessment of the quantity of coal burned and mercury content contained therein, as well as of the mercury content in bottom ash, chimney soot, boiler deposits and their quantities, annual mercury emissions and its factor of emission into the atmosphere were defined. It was defined that the mercury emission factor for the investigated case of a single-family house is at a level of 0.56 µg/MJ. It was shown that 41.4% of the mercury contained in coal burned in a home heating boiler is emitted into the atmosphere, 57.0% is adsorbed by chimney soot, 0.3% by boiler heater deposits and 1.3% passes into bottom ash. Annual mercury emissions into the atmosphere from the single-family house concerned was 79 mg. Mercury emissions can be significantly reduced by households by separating any overgrowths with pyrite from coal. The solution proposed would enable a reduction in annual mercury emissions into the atmosphere in Poland from the domestic user sector by 58.5% (0.351 Mg). The factor of emission of mercury into the atmosphere would be 0.23 µg/MJ.