Influence of CaO on in-situ tar formation during the co-pyrolysis of coal and cow dung in a Py-GCMS

Abstract

Co-pyrolysis is one of the most important way to achieve the efficient and clean co-conversion of animal waste and coal. CaO has been verified as an efficient additive to enhance the synergy between them but the catalytic mechanism of CaO on co-pyrolysis process is still unclear. In this paper, the influence of CaO on tar composition during the co-pyrolysis of cow dung (CD) and Meihuajing (MHJ) coal and their interaction are in-situ investigated by using a Py-GCMS analyser. The results indicate that the influence of CaO on interaction between CD and MHJ is different at each temperature range, and affected by the additional amount of CaO. Positive synergistic effect between coal and cow dung presents on the hydrocarbons production in 350-450 °C and the formation of oxygen-containing compounds in 450-550 °C after CaO is added. The area content of aliphatic hydrocarbons containing olefins in tar increases with the addition amount of CaO in 50-450 °C, but excessive CaO hinders the formation of these compounds in 550-850 °C. Additionally, the influence of CD-MHJ interaction during co-pyrolysis on different tar compositions varies with the temperature range and the addition of CaO.