Facile Synthesis of MgO Nanoparticle-Embedded Fe/N/S Codoped Carbon Materials from Oily Sludge for Efficient CO2 Capture

Abstract

Oily sludge generated from the modern petrochemical industry is a large-scale hazardous solid waste. Pyrolysis with efficient catalysts is considered as a promising technology to convert the oily sludge into value-added chemicals or fuels without significant impact on the environment, but the solid char with spent catalysts does not find an application. In this study, the solid char obtained from catalytic pyrolysis of the oily sludge is applied as an adsorbent for CO2 capture. The char can be regarded as MgO nanoparticle-embedded Fe/N/S codoped carbon (MgO·FeOx@NSC) based on its structure and composition. MgO·FeOx@NSC presents a favorable performance toward CO2 capture. The maximum CO2 adsorption capacity is 4.57 mol/kg, and this value remains unchanged for more than 10 cycles of reuse. The mechanism for CO2 capture is analyzed with Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). Physical adsorption and chemical interaction are identified as the primary contributors to the CO2 adsorption with MgO·FeOx@NSC, in which MgO, nitride-N, and sulfide-S are the main species contributing to the chemical interactions between CO2 and MgO·FeOx@NSC. This study will open up a new way for the sustainable management of hazardous organic solid wastes.