Development of novel sorbents for mercury control at elevated temperatures in coal-derived syngas: results of initial screening of candidate materials

Abstract

For next-generation coal-fired power plants such as the integrated gasification combined cycle (IGCC), controlling mercury emissions from the flue gas (turbine exhaust) may not be the most cost-effective option. Rather, it may be more advantageous to remove mercury from the fuel gas (syngas) before its combustion in a gas turbine. This approach aims to maintain the thermodynamic advantages of the IGCC while achieving the desired mercury control. Supported by U.S. Department of Energy's National Energy Technology Laboratory, RTI is screening chemically reactive solid sorbents to remove mercury. The concept of using reactive solid sorbents is analogous to technology RTI has developed for elevated-temperature syngas desulfurization. The goal is a sorbent tailored to remove mercury at the conditions of the syngas produced in a gasifier fed with carbonaceous feedstocks such as coal and petroleum coke. For the sorbent screening program, RTI has assembled a mercury vapor exposure apparatus and is evaluating selected sorbents for mercury removal at high temperatures (400 to 600 °F) in the simulated syngas. The initial testing has identified several effective candidate sorbents, while confirming the expected failure of conventional sorbents under high-temperature conditions. Mercury uptake by each sorbent was measured by analyzing the exposed material. The experimental protocol includes breakthrough testing and additional quality control runs without a sorbent present.