Emission characteristics of nitrogen and sulfur containing pollutants during the pyrolysis of oily sludge with and without catalysis

The oily sludge is a category of hazardous solid waste generated in petrochemical industries. Pyrolysis is an efficient approach for sustainable treating the oily sludge with limited environmental impacts, but the pollutant emission during the pyrolysis process is still a big challenge. Herein, the emission characteristics of nitrogen (N) and sulfur (S) containing pollutants during the oily sludge pyrolysis with and without catalysis was illuminated via a TG-FTIR-MS system (ThermoGravimetric-Fourier Transform InfaRed-Mass Spectroscopy). The FeMg layer double hydroxide (FeMg LDH) was employed as a catalyst for pyrolysis. The emission characteristics of six inorganic N-/S-containing pollutants, as well as ten organic N- and nine S-containing pollutants were analyzed. The results indicate that the FeMg LDH could efficiently suppress the emission of N-/S-containing pollutants. The amide and heterocyclic-N species were identified as primary resources of N-containing pollutants emission. The aliphatic- and disulfides-S were the main contributions to the S-pollutants emission. Comprehensive analysis of pollutants emission characteristics for oily sludge pyrolysis could provide a better understanding for sustainable managements of the hazardous solid wastes.

Automated summary

This study investigated the emission characteristics of nitrogen (N) and sulfur (S) containing pollutants during the pyrolysis of oily sludge with and without the catalyst FeMg layer double hydroxide (FeMg LDH). The results showed that FeMg LDH could efficiently suppress the emission of N-/S-containing pollutants, with amide and heterocyclic-N species identified as primary sources of N-containing pollutants emission, and aliphatic- and disulfides-S as the main contributions to S-pollutants emission. Comprehensive analysis of pollutants emission characteristics could provide insights for sustainable management of hazardous solid wastes.