Hydrogen Production by Aqueous Phase Reforming of Synthetic Sewage Using Pt/C Catalyst: Effect of Reaction Parameters and Pre-Treatment Strategies

Domestic sewage containing low concentrations of oxygenated compounds can be effectively converted into H-2 and other gaseous fractions via catalytic aqueous phase reforming (APR). Starch, glucose, meat peptone and sunflower oil were chosen as model compounds for carbohydrates, proteins and lipids respectively. Trials were performed in a stirred batch reactor and reaction parameters, viz. catalyst loading (0-10 kg/m(3)), temperature (180-235 & DEG;C), pH (5-9) and reaction time (1.5-6 h) were optimized. A commercial 5% Pt/C catalyst was employed for the study. Another noble metal catalyst Ru/C was also investigated but Pt/C was found to be superior. Along with H-2 production, Chemical Oxygen Demand (COD) reduction of sewage was studied. For optimum reaction conditions, H-2 production was 2.13 mmoles/CODg,i (where, CODg,i refers to initial COD in gram) and 60% COD reduction was observed. A process integrating hydrothermal carbonization followed by APR of the hydrothermal liquor was investigated to check for its effect on the H-2 yield. Electron microscopy, powder X-ray diffraction, X-ray photoelectron spectroscopy, Fourier Transform Infrared spectroscopy, H-2 chemisorption, NH3 Temperature Programmed Desorption and BET analysis were used to investigate several aspects of the Pt/C catalyst. Kinetic parameters like Turnover Frequency (TOF) and apparent activation energy (E-a) were determined. E-a was estimated to be 19.5 kJ/mol. This work reported an application of APR to effectively utilize the wastewater for producing valuable gases along with the treatment of wastewater making it suitable for industrial use.