Master of Science (MS)
Lignocellulosic biomass is a promising feedstock for producing liquid fuels via synthetic gas (syngas) and Fischer Tropsch Synthesis (FTS). Syngas produced from biomass has low H2/CO ratio (~0.7/1) and high concentration of CO2. In order to produce liquid hydrocarbons from this syngas, a catalyst must be used to increase the H2/CO ratio to 2 or higher. This catalyst must also have reasonable reverse water-gas-shift (R-WGS) activity in a CO2 rich environment. In this study, two 100Fe/4Cu/4K/6Zn were prepared using coprecipitation (Cat_C) and impregnation (Cat_I) methods. The effects of these preparation methods on the catalyst structure and FTS performance in biomass syngas were investigated. The catalysts were characterized by Scanning Electron Microscopy and Energy Dispersive X-Ray spectroscopy (SEM/EDX), H2 temperature programmed reduction (H2-TPR), CO temperature programmed reduction (CO-TPR), CO temperature programmed desorption (CO-TPD), temperature programmed hydrogenation (TPH), and CO2 temperature programmed desorption (CO2-TPD). Syngas used in this work was derived from gasifying Southern Pine woodchips at the USDA Forest Service in Pineville, LA and sent to LSU where the FTS studies were carried out. The final composition of the syngas after the cleaning and compressing process is 3.1% CH4, 11% CO2, 17 % H2, 22% CO, and balance N2. Even though coprecipitation and impregnation methods have been compared in previous studies for FTS of pure syngas, there are no comparisons between these two synthesis methods for FTS of biomass-derived syngas. The results show that the coprecipitated catalyst has higher extent of reduction, carburization, and Hagg carbide (Fe2C5) formation impregnated catalyst. As a result, the coprecipitated catalyst has higher CO+CO2 conversion and C5+ selectivity than the impregnated catalyst in a CO2 rich environment.
Document Availability at the Time of Submission
Secure the entire work for patent and/or proprietary purposes for a period of one year. Student has submitted appropriate documentation which states: During this period the copyright owner also agrees not to exercise her/his ownership rights, including public use in works, without prior authorization from LSU. At the end of the one year period, either we or LSU may request an automatic extension for one additional year. At the end of the one year secure period (or its extension, if such is requested), the work will be released for access worldwide.
Mai, Khietlethanh, "Effects of Different Preparation Methods on Structure and Catalytic Behavior of Iron-Based Catalyst via Fischer Trospch Synthesis of Biomass-Derived Syngas" (2014). LSU Master's Theses. 2360.
Spivey, James J.