(313d) Catalytic Gasification: A Sustainable Waste Management Alternative

This research focuses on advancing the current knowledge of a catalytic gasification process as a potential in-situ resource utilization and waste management system. This research has significance in a variety of engineering applications, but is of particular relevance towards municipal waste management and as an in-situ resource utilization alternative for advancing space exploration.

In this technology, typically referred to as Trash to Supply Gas (TtSG), the catalytic gasification reaction mechanism evolves through four reactions. The first two reactions are liquid-phase oxidation reactions of long-chain polymers (or substrates). The liquid phase oxidation reactions produce carbon monoxide, carbon dioxide, and water. The oxidation reactions are complemented by two gas-phase reactions: the Water Gas Shift (WGS) and the Sabatier (or methanation) reaction. These two reactions are the main stages in the pathway of producing hydrogen and methane in this technology.

The focus of this research is elucidating the reaction kinetics for the liquid phase oxidation reactions. A detailed analysis of the gas-phase kinetics where the Sabatier and Water-Gas Shift reactions complement each other to complete the Wet Thermal Catalytic Oxidation of long-chain polymers to syngas is presented. Current efforts including the connection of transport phenomena with gas phase kinetics for the formulation of an overall model are addressed in this paper.

Results obtained in a research grade laboratory reactor with two model substrates: cellulose and polyethylene, are presented. Cellulose and polyethylene were chosen as model substrates because they exhibit marked differences under the current reaction conditions being studied. Cellulose remains solid during catalytic gasification experiments, while polyethylene melts prior to reaction conditions. The reaction time is varied between 2 and 24 hours. Gas products are collected and analyzed with Gas Chromatography. In addition, characterization of the liquid and solid residuals includes Differential Scanning Calorimetry, Thermo-Gravimetric Analysis, and Scanning Electron Microscopy. The results clearly demonstrate the potential of catalytic gasification as a sustainable waste management alternative.