Chemical Pre-Treatment of Coal and Carbon Black: Implications for Electrolytic Hydrogen Generation and Electrochemical/Thermal Reactivity

Abstract

Acid digestion and oxidation with H 2O 2 were investigated as chemical pre-treatments that could improve the generation of H 2 from coal as well as carbon black slurries by electrolysis. Among the different 1 M acids that were used in this study, namely HClO 4+?, H 2SO 4+? and HNO 3, digestion of Texas lignite coal (TXLC) with HClO 4+? was found to yield the best results. It increased the polarization time (and hence the amount of H 2 generated at the cathode) during the galvanostatic polarization experiments by 50 compared to the untreated TXLC sample. On the other hand, acid digestion of carbon black (SRC-401) adversely affected the polarization time in all cases with a maximum reduction in polarization time (50) in the case of HNO 3. H 2O 2 treatment of medium (DECS10) and high rank (DECS21) coals did not improve the galvanostatic polarization behavior of their respective slurries, while low rank coals such as TXLC showed a moderate increase in the polarization time. This modification of the galvanostatic polarization behavior as a result of both types of chemical pre-treatments was correlated with changes in the surface area andor surface functional groups as well as solubilization of the inherent mineral content in the coal samples. Finally simultaneous thermogravimetric and differential scanning calorimetric analyzes afforded insights into the consequences of the chemical pre-treatments on the thermal reactivity of the coal and carbon black samples. ? 2012 The Electrochemical Society.