Application of mercury temperature programmed desorption (HgTPD) to ascertain mercury/char interactions

This work investigates the scope of a mercury temperature programmed desorption (HgTPD) technique for identifying mercury species in solids. The specific objective of this study was to clarify the mechanism of mercury retention by chars used as sorbents in coal combustion in air and oxy-combustion atmospheres based on the identification of the mercury species retained. Different mercury species were identified by HgTPD depending on the flue gas composition and the type of char. The results led to the conclusion that depending on these conditions the main mechanism of mercury retention will be the interaction of mercury with organic matter, or the interaction of mercury with sulfur to form HgS. In a few particular cases Hg2(NO3)22H2O was produced on the char surface. It was found that HgTPD is a highly useful technique for investigating the different mechanisms of mercury/char/gas interactions.The financial support for this work was provided by the National Research Program under project CTM2011–22921. The authors thank the Energy Research Centre of the Netherlands for supplying the chars employed in this study, the Spanish Research Council (CSIC) for awarding Ms. Marta Rumayor a JAE-predoc fellowship and PCTI Asturias for awarding Ms. Nuria Fernandez-Miranda a pre-doctoral fellowship.Peer reviewe