Ruthenium-based catalyst development for Fischer-Tropsch synthesis
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Journal Title
Journal ISSN
Volume Title
Kemian tekniikan korkeakoulu |
Master's thesis
Authors
Date
2022-10-18
Department
Major/Subject
Chemical and Process Engineering
Mcode
CHEM3043
Degree programme
Master's Programme in Chemical, Biochemical and Materials Engineering
Language
en
Pages
89+19
Series
Abstract
One of the most significant reactions in gas-to-liquid (GTL) technology is the Fischer-Tropsch synthesis (FTS), in which gaseous CO and H2 enter the reactor and liquid hydrocarbons exit. The primary goals of the thesis were to understand the current status of ruthenium-based FTS catalysts and to investigate the activity and selectivity of various Ru-based FTS catalysts. The literature part of the thesis focused on key parameters of catalyst design, including the use of different catalyst supports, promoters, active metal, metal particle size, metal loading, and preparation methods. In addition, the application of catalysts in microreactors is reviewed. In the experimental part, the activity and selectivity of different Ru-based catalysts were studied. Three 3 wt. % Ru-based catalysts on mesoporous silica support were prepared by vacuum sequential impregnation. Co and Zr promoters were investigated with metal loadings of 10 wt. % and 1.5 wt. %, respectively. Along with three prepared catalysts, one commercial Ru-based catalyst (5 wt. % Ru/Al2O3) was investigated in a fixed bed reactor at 20 bar, and H2/CO molar ratio of 2.0. The catalytic activity and product selectivity was studied at different temperatures and Gas Hourly Space Velocities (GHSV). Overall, the commercial catalyst was the most active catalyst. Among the prepared catalysts, the Ru-Co/SiO2 catalyst showed the highest activity while, the Ru/SiO2 catalyst showed the lowest activity at similar reaction conditions. The catalytic activity increased around 1.5 times with 10 °C rise in temperature. Overall, the product distribution is dependent on conversion levels. The unpromoted Ru catalyst, even at higher conversion level, showed lower methane selectivity, while the Ru-Co/SiO2 catalyst showed the highest methane selectivity. The Ru-Zr/SiO2 catalyst showed the lowest Olefin-to-Paraffin ratio, while the commercial catalyst showed the highest. The selectivity of long-chain hydrocarbons was highest for the Ru/SiO2 catalyst and the lowest for the Ru-Co/SiO2 catalyst. The Ru/SiO2 catalyst showed the highest probability of chain growth (α-value), while the commercial catalyst showed the lowest. The mesoporous silica support could have contributed to an increase in the α-value of all the prepared catalysts.Description
Supervisor
Puurunen, RiikkaThesis advisor
Heikkinen, NikoKeywords
Fischer-Tropsch, ruthenium, promoters, supports