The pyrolysis characteristics of oil sludge was investigated using thermogravimetric analysis-Fourier transform infrared spectrometer(TG-FTIR)in N_2/CO_2 atmosphere.It was found that the pyrolysis process could be divided into three main stages

corresponding to the light hydrocarbons devolatilization(300 ℃~500 ℃)

carbonates decomposition(500 ℃~800 ℃)

and stable macromolecular structure of organic matter decomposition(900 ℃~1100 ℃).The Coats-Redfern method was applied to calculate the kinetic parameters of the main stages of oil sludge pyrolysis

and the results show that the activation energy was much higher in the high-temperature stage.The CO_2 atmosphere had no obvious influence on the oil sludge pyrolysis for both low-temperature and middle-temperature stages

but in high-temperature stage

the activation energy in CO_2 atmosphere obviously increased compared to N_2 atmosphere.By FTIR analysis

it was found that the major volatile gases released from oil sludge pyrolysis mainly composed by CO_2

CO

CH_4

and other hydrocarbons.In the high-temperature stage

there was a large amount of methyl release

which was dramatically promoted by CO_2 atmosphere.