Microwave-assisted ethanol decomposition over pyrolysis residue of sewage sludge for hydrogen-rich gas production

Microwave-assisted ethanol decomposition over pyrolysis residue of sewage sludge (PRSS) was investigated in a multi-mode microwave (MW) oven, and was compared with ethanol decomposition over a commercial activated carbon (AC). The results indicated that PRSS showed higher MW heating performance than AC. Under the same microwave power (MP), the temperature of catalyst bed, hydrogen produc0oij9tion and ethanol conversion over PRSS were higher than that over AC. Both hydrogen production (per unit volume of ethanol) and ethanol conversion increased with the increase of MP, whereas decreased with the increase of the volumetric hourly space velocity of ethanol (VHSVeth). Additionally, comparison between ethanol decomposition by MW and conventional heating was also conducted. Results indicated that MW heating was much more beneficial for hydrogen production than conventional heating, and the energy efficiency of hydrogen production under MW heating was much higher than conventional heating. Finally, carbon nanofilaments formation over PRSS and AC were observed under MW heating. The size and structures of carbon nanofilaments over PRSS and AC were significantly different with each other, which may be strongly correlated with the formation of micro-plasmas during MW heating.