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Rhim, Geun Bae,Hong, Seok Yong,Park, Ji Chan,Jung, Heon,Rhee, Young Woo,Chun, Dong Hyun American Scientific Publishers 2016 Journal of Nanoscience and Nanotechnology Vol.16 No.2
<P>Fischer-Tropsch synthesis (FTS) was carried out over nanocrystalline ferrihydrite-based (Fe9O2(OH)(23)) catalysts activated by different reducing agents: syngas (H-2+CO), CO, and H-2. The syngas activation successfully changed the ferrihydrite-based catalysts into an active and stable catalytic structure with chi-carbide (Fe2.5C) and epsilon'-carbide (Fe2.2C). The crystal structure of the catalysts obtained by syngas activation was similar to the structure obtained by CO activation; this similarity was probably due to the peculiar reduction behavior of the ferrihydrite-based catalysts, which exhibit much greater reducibility in CO atmosphere than in H-2 atmosphere. The performance of the catalysts activated by syngas was much higher than the performance of the catalysts activated by H-2 and was comparable to the performance of the catalysts activated by CO. This strongly demonstrates that the ferrihydrite-based catalysts are advantageous for industrial FTS processes because syngas can be commonly used for both activation pre-treatment and subsequent reaction.</P>
A hybrid modeling framework for efficient development of Fischer-Tropsch kinetic models
Ji Hee Kim,Geun Bae Rhim,Naeun Choi,Min Hye Youn,Dong Hyun Chun,Seongmin Heo 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.118 No.-
Fischer-Tropsch synthesis (FTS) receives an extensive attention as it can be used to produce variouschemicals and fuels, such as linear alpha olefin, gasoline and jet fuel, in a sustainable way. While a kineticmodel can help optimize the operating conditions of FTS reactors for a specific product portfolio, such amodel is very challenging to develop due to the large number of species and reactions involved in FTS. Tothis end, in this work, we propose a hybrid modeling framework to efficiently build a kinetic model forFTS. Specifically, experiments are conducted using a Fe-Cu-K-SiO2 catalyst with the following operatingvariables: pressure, temperature, H2/CO ratio in syngas, and gas hourly space velocity. Then, using theexperimental data, the effectiveness of the proposed framework is illustrated, which consists of threekey components. The overall LHHW model is first used to predict the overall consumption rates of COand H2 as well as the production rates of CO2 and overall hydrocarbons. Then, a convex piecewise linearfitting problem is formulated for the ASF distribution model, which can identify the break points (wherethe value of chain growth probability a changes) with global optimality. Finally, surrogate modeling isperformed to obtain the models describing the changes in the optimal a values with respect to the operatingconditions. The final model showed the overall relative error of 9.98% for CO, CO2 and H2, and 15.8%for hydrocarbons, which are comparable to the values reported in the literature.
Park, Ji Chan,Jang, Sanha,Rhim, Geun Bae,Lee, Jin Hee,Choi, Hyunkyoung,Jeong, Heon-Do,Youn, Min Hye,Lee, Dong-Wook,Koo, Kee Young,Kang, Shin Wook,Yang, Jung-Il,Lee, Ho-Tae,Jung, Heon,Kim, Chul Sung,Ch Elsevier 2018 Applied catalysis. A, General Vol.564 No.-
<P><B>Abstract</B></P> <P>Improvement of activity, selectivity, and stability of the catalyst used in Fischer-Tropsch synthesis (FTS) to produce targeted hydrocarbon products has been a major challenge. In this work, the potassium-doped iron-carbide/alumina (K-Fe<SUB>5</SUB>C<SUB>2</SUB>/Al<SUB>2</SUB>O<SUB>3</SUB>), as a durable nanocatalyst containing small iron-carbide particles (∼ 10 nm), was applied to high-temperature Fischer-Tropsch synthesis (HT-FTS) to optimize the production of linear alpha olefins. The catalyst, suitable under high space velocity reaction conditions (14–36 N L g<SUB>cat</SUB> <SUP>−1</SUP> h<SUP>−1</SUP>) based on the well-dispersed potassium as an efficient base promoter on the active iron-carbide surface, shows very high CO conversion (up to ∼90%) with extremely high activity (1.41 mmol<SUB>CO</SUB> g<SUB>Fe</SUB> <SUP>−1</SUP> s<SUP>−1</SUP>) and selectivity for C<SUB>5</SUB>–C<SUB>13</SUB> linear alpha olefins.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The potassium-doped iron-carbide/alumina nanocatalyst was prepared for effective production of linear alpha olefins. </LI> <LI> The active iron-carbide nanoparticles (∼10 nm) with potassium on gamma-alumina could enhance catalytic performance. </LI> <LI> The catalyst showed high stability and activity for high-temperature Fischer-Tropsch synthesis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>A potassium-doped iron-carbide/alumina nanocatalyst shows very high CO conversion (∼90%) and significant productivity for C<SUB>5</SUB>–C<SUB>13</SUB> linear alpha olefins in Fischer-Tropsch synthesis under high space velocity conditions.</P> <P>[DISPLAY OMISSION]</P>