Co-Pyrolysis of Coals and Lube Oil Wastes in a Bench-Scale Unit

Abstract

The co-pyrolysis of a lube oil waste (LOW) and two coals has been carried out. The main objective of this study is mainly to compare product yields from co-pyrolysis with those obtained in the pyrolysis of coal and LOW alone. The influence of temperature, pressure, and coal nature on the yields obtained has been studied. The work has been carried out at bench scale using mixtures of coal and LOW in a mass ratio of 50/50. Three temperatures, 600, 650, and 700 °C and three pressures 0.1, 0.5, and 1 MPa have been studied. Two coals largely differing in rank have been used in order to state the influence of coal nature. Occurrence of synergetic effects on some products has been observed which confirms that co-pyrolysis of LOW and coal as a mixture enhances the transfer of coal hydrogen to valuable petrochemical products that otherwise would be transferred to molecular hydrogen if coal was pyrolyzed alone. Comparing the theoretical values with the experimental ones, there is a synergy in the hydrogen transferred to CH4 and light alkanes, ethylene, and propylene that increases as temperature increases and the H2 transferred to >C 4 compounds does not reveal synergy. However, for the hydrogen transferred to BTX, the theoretical values remain similar to the experimental ones. The synergy in the hydrogen transferred to CH4 and light alkanes increases, with pressure, and also the H2 transferred to BTX. However, pressure does favor the synergy in the hydrogen transferred to BTX. The same considerations apply to both coal/oil mixtures, but the effect observed for the Figaredo coal (the highest rank one)/LOW are lower than for the Samca coal/LOW.