Selective catalytic reduction (SCR) technology increasingly is being applied for controlling emissions of nitrogen oxides (NOx) from coal-fired boilers. Some recent field and pilot studies suggest that the operation of SCR could affect the chemical form of mercury (Hg) in coal combustion flue gases. The speciation of Hg is an important factor influencing the control and environmental fate of Hg emissions from coal combustion. The vanadium and titanium oxides, used commonly in the vanadia-titania SCR catalyst for catalytic NOx reduction, promote the formation of oxidized mercury (Hg2+). The work reported in this paper focuses on the impact of SCR on elemental mercury (Hg0) oxidation. Bench-scale experiments were conducted to investigate Hg0 oxidation in the presence of simulated coal combustion flue gases and under SCR reaction conditions. Flue gas mixtures with different concentrations of hydrogen chloride (HCl) and sulfur dioxide (SO2) for simulating the combustion of bituminous coals and subbituminous coals were tested in these experiments. The effects of HCl and SO2 in the flue gases on Hg0 oxidation under SCR reaction conditions were studied. It was observed that HCl is the most critical flue gas component that causes conversion of Hg0 to Hg2+ under SCR reaction conditions. The importance of HCl for Hg0 oxidation found in the present study provides the scientific basis for the apparent coal-type dependence observed for Hg0 oxidation occurring across the SCR reactors in the field.

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A series, consisting of 52 benzamidine derivatives, was evaluated for inhibitory activity against homogeneous boar sperm acrosin. All of the compounds in the series proved to be more potent than benzamidine (Ki = 4.0 x 10(-6) M), with one of the derivatives, alpha-(4-amidino-2,6-diiodophenoxy)-3-nitrotoluene (compound 16), showing outstanding potency with a Ki value of 4.5 X 10(-8) M. Although all of the derivatives were effective acrosin inhibitors, structural specificity was observed within homologous groups of compounds. The information gained from this preliminary study should prove extremely beneficial in the design and synthesis of future acrosin inhibitors.

52 Benzamidin‐Derivate (I)‐(IV) werden teilweise dargestellt und auf Acrosin‐inhibierende Wirkung untersucht.