Catalytic Pyrolysis of Used Engine Oil over Coal Ash into Fuel-like Products

The present paper reports on the conversion of spent lubricating oil (SLO) into useful fuel-like products through two-stage pyrolysis. Liquid pyrolysates (LPs) from the first stage were obtained using prebaked clay (PBC) as adsorbent and subjected to second stage pyrolysis over coal ash (CA) as catalyst. The PBC and CA were characterized by using morphological, elemental, surface, and crystallographic properties. The influence of CA concentration on the yield of LPs and their compositions in terms of hydrocarbon range and hydrocarbon group types distributions were studied. Fuel properties such as density, specific gravity, API gravity, ash content, kinematic viscosity, pour point, aniline point, diesel index, cetane number, and calorific value of the thermally derived pyrolysate (TDLP) as well the catalytically derived liquid pyrolysate (CDLP) in comparison with the ASTM standard values were also studied. The results indicate that the CA when used in low concentration exhibited good activity and selectivity toward formation of the LPs having fuel value comparable with diesel fuel.