The Effect of Packing Material Properties on Tars Removal by Plasma Catalysis

Plasma catalysis has been utilized in many environmental applications for removal of various hydrocarbons including tars. The aim of this work was to study the tars removal process by atmospheric pressure DBD non-thermal plasma generated in combination with packing materials of various composition and catalytic activity (TiO2, Pt/gamma Al2O3, BaTiO3, gamma Al2O3, ZrO2, glass beads), dielectric constant (5-4000), shape (spherical and cylindrical pellets and beads), size (3-5 mm in diameter, 3-8 mm in length), and specific surface area (37-150 m(2)/g). Naphthalene was chosen as a model tar compound. The experiments were performed at a temperature of 100 degrees C and a naphthalene initial concentration of approx. 3000 ppm, i.e., under conditions that are usually less favorable to achieve high removal efficiencies. For a given specific input energy of 320 J/L, naphthalene removal efficiency followed a sequence: TiO2 > Pt/gamma Al2O3 > ZrO2 > gamma Al2O3 > glass beads > BaTiO3 > plasma only. The efficiency increased with the increasing specific surface area of a given packing material, while its shape and size were also found to be important. By-products of naphthalene decomposition were analyzed by means of FTIR spectrometry and surface of packing materials by SEM analysis.