Auxiliary effect of CO₂ on pyrolysis of oily sludge

Abstract

The efficient recovery and conversion of energy in oily sludge has great prospects. In this article, the main objective is to investigate the impact of the addition of CO₂ during the pyrolysis of oily sludge on energy recovery and conversion by thermogravimetric analysis (TGA) and compare the effect with the traditional pyrolysis effect from the perspective of thermal conversion behavior, products composition, and kinetics analysis. The results of the experiment showed that in the CO₂ atmosphere, the main weight loss temperature of oily sludge was mainly concentrated in the range of 300–500 °C, which is lower than the reaction temperature range of traditional pyrolysis. The yields of CO and H₂ in the products have been greatly improved, and the highest proportion in the gas products can reach 19.29% and 22.38%, respectively. The E_a (activation energy) values of oily sludge were determined to be in the range of 40–120 kJ·mol⁻¹ with the conversion between 0.2 and 0.8 via DAEM, KAS, Starink, and FWO methods, respectively, in which the FWO method has shown the strongest adaptability. The results of this study provide reference values for practical engineering applications.

Keywords:

• Oily sludge
• pyrolysis
• CO₂
• kinetics analysis
• iso-conversional method

Data available statement

All data, models, and code generated or used during the study appear in the submitted article.

Additional information

Funding

The research was supported by the State Key Laboratory of Pollution Control and Resource Reuse Foundation (No. PCRRF19023), Natural Science Foundation of Shandong Province (No. ZR2020QE199), Key Research and Development Program of Liaoning Province (No. 2020JH2/10300099), Fundamental Research Funds for the Central Universities (No. 18CX02150A), Natural Science Foundation of Shandong Province (ZR2019BEE023, ZR2020QE199) and the Opening Fund of State Key Laboratory of Heavy Oil Processing (SKLOP202003001). They also thank the State Key Laboratory of Heavy Oil in China University of Petroleum (East China).