(150d) Hydrogen Production From Oleic Acid and Starch Over Supported Metal Catalysts in Supercritical Water

Supercritical water gasification (SCWG) is a process that is currently being developed for the gasification of biomass in supercritical water. Hydrogen production from sewage sludge may be a solution for cleaner fuel and the sewage sludge disposal problem. The catalytic supercritical water partial oxidation process principle is to utilize the drastic changes of the physical and chemical properties of water above its critical conditions. These properties allow for a nearly complete conversion of sludges into energy-rich fuel gases, namely hydrogen, methane, and carbon dioxide. Because sewage sludge usually contains plenty of lipids, and carbohydrate and to understand the sewage sludge model compounds behavior at supercritical water conditions, Oleic acid and Starch were used as the model compounds of lipids, and carbohydrate respectively. The catalytic supercritical water gasification (SCWG) of oleic acid and starch in the presence of several commercial catalysts, namely; Pd (Palladium)/AC, Pt (Platinum)/AC, Ni/silica-alumina, and hydrogenation catalyst (KATALCO) has been investigated in a heated batch reactor. To avoid the reactions in subcritical conditions, de-ionized water and the catalyst were first heated and pressurized to desired temperature. The reactants were then injected into the reactor against it pressure at the reaction supercritical conditions by employing syringe pump. This paper presents the experimental results obtained at reaction conditions of 500°C, 28 MPa, and 30 minute residence time. The main gas components were carbon dioxide (CO2), carbon monoxide (CO), hydrogen (H2), and methane (CH4). The influence of using different catalyst for the gasification and hydrogen gas yield were studied and discussed. The liquid after reaction product characteristics were studied by comparing both the Chemical Oxygen Demand (COD) and COD reduction efficiency with the quality standard of domestic wastewater. In addition, the effect of catalysts on the Chemical Oxygen Demand (COD) destruction efficiency were also investigated and reported.