Modified with Transition Metals (Cu, Fe, Ni, Co) as Efficient Deoxidizers for O2 Removal from Low-Concentration Coal Bed Methane

Abstract

Deoxidizer Na2S/AC was modified with transition metal ions (Co2+, Ni2+, Fe3+, and Cu2+) by co-impregnation and step-by-step impregnation methods. Those deoxidizers were characterized and tested for the removal of O2 from low-concentration coal bed methane. Results showed that the effective deoxidizing amount of deoxidizers (QO2) and conversion rate of Na2S (CNa2S) of the deoxidizers are in the following order: Co-Na2S/AC > Ni-Na2S/AC > Fe-Na2S/AC > Na2S/AC > Cu-Na2S/AC. As compared to that of the deoxidizer Na2S/AC, the content of reactive oxygen species (O£–) of the modified deoxidizers was enhanced with the doping of transition metal ions (Co2+, Ni2+, Fe3+, and Cu2+). The more content of O£– on the deoxidizer was, the higher deoxidizing activity there was when the dispersion of Na2S and metal ions of deoxidizers was higher. The deoxidizer Co-Na2S/AC had the largest content of O£– and higher dispersion of Na2S and Co2+, and this made it the largest QO2 (54.88 mL/g) and CNa2S (75.50%) at 200 °C. However, ...