Online Detection of Selenium and Its Retention in Reducing Gasification Atmosphere

The emission of selenium from coal gasification processes can cause harm to the environment and downstream equipment. With upcoming legislation, reliable detection as well as control of such gas species become crucial. This study therefore addresses the development and successful employment of an online analytical method, based on the direct introduction of a simplified flue gas (H-2, H2O, H2Se, Ar) into an ICP-MS. In combination with matrix matched calibration, the calculated and verified detection limits of H2Se lie below 1 ppbv, thus being comparable to current offline methods. These low detection limits and the high temporal resolution (>1 Hz) enable the use of this method as a quick and robust tool for the lab- and bench-scale performance evaluation of sorbent materials. As a case study, Zn/Al2O3 was tested toward H2Se capturing at warm temperatures (150-350 degrees C). The results show that both, the support and the active phase, interact with the contaminant. While gamma-Al2O3 can retain H2Se at dry reaction conditions, a Zn phase is needed for its capture in steam laden gas.