Hydrogen production from supercritical water gasification of chicken manure

Abstract

The gasification characteristics of chicken manure in supercritical water (SCW) were investigated in a fluidized-bed reactor. Effects of reaction parameters such as reaction temperatures, manure concentrations and catalytic effect of activated carbon on the gasification were studied. The results showed that the temperature play a key role in the formation of gaseous products. Chicken manure was almost completely gasified at 620°C without addition of catalyst and the carbon gasification efficiency can reach up to 99.2%. The liquid and solid products were characterized by COD, SPE-GC/MS, SEM, EDX and FTIR. The main compositions of liquid products were phenol and substituted phenols, N-heterocyclics, benzene and substituted benzenes, carbocyclics. The types of organic compounds in liquid products decreased quickly with the increase of temperature. The FTIR spectra of solid products showed a lower content of carbohydrates and higher content of aromatic structures compared to the initial chicken manure. N-heterocyclic compounds had been detected in both solid and liquid products. Activated carbon as a catalyst could improve the hydrogen yield significantly and promote carbon gasification efficiency at a lower temperature. The maximum hydrogen production of 25.2 mol/kg was achieved at 600°C with activated carbon loading of 6 wt%. Besides, activated carbon showed a good removal ability of inorganic species, specifically the metal cations in chicken manure.