Low cost catalytic sorbents for NO_x reduction - 1. Preparation and characterization of coal char impregnated with model vanadium components and petroleum coke ash

Spanish coal, char and activated char doped with model vanadium components (V₂O₅ and NH₄VO₃) and petroleum coke ash (enriched in V, Fe, and Ni) were prepared and characterized as potential catalytic sorbents for NO_x reduction. The phase-mineral and chemical composition, content and behavior (capture, retention, distribution, and redistribution) of transition metals, as well as morphogenesis, surface area, acid-base properties, surface active sites and oxidation-reduction transformations of the catalytic sorbents were characterized. It was found that minerals and phases such as anhydrite, calcite, clay minerals, pyrite, pyrrhotite, magnetite and fusinoid-type ingredients have a leading role for the behavior of loaded transition metals. Some original (pyrite, jarosite, shcherbinaite, coulsonite, trevorite, Ni oxide) and newly formed (pyrrhotite, magnetite, wuestite, hematite, paramontroseite, karelianite) Fe, V and Ni minerals in the catalytic sorbents are perspective redox indicators for the physicochemical conditions in such complex system. The data indicate that the V-Fe-Ni containing minerals dispersed onto and into the carbon support may be the most active catalytic sites. The preparation procedure that could provide the most favorable conditions for the production of effective and low cost catalytic sorbents for NO_x reduction is also described.