Heon Jung

Highly activated K-doped iron carbide nanocatalysts designed by computational simulation for Fischer–Tropsch synthesis

Although the reaction results of numerous iron-based Fischer–Tropsch synthesis catalysts containing various promoters have been reported, the research on their theoretical foundation is still insufficient. In the present work, highly activated K-doped χ-Fe5C2/charcoal nanocatalysts were designed using calculations based on density functional theory (DFT), and then prepared using a melt-infiltration process and a subsequent incipient-wetness method of K precursors. The catalyst at K/Fe = 0.075 in an atomic ratio that bears small iron carbide nanoparticles of ∼18 nm showed the highest activity (1.54 × 10−4 molCO gFe−1 s−1) and the best hydrocarbon yield (1.41 × 10−3 gHC gFe−1 s−1), as well as a good selectivity for gasoline-range (C5–C12) hydrocarbon products in the high-temperature Fischer–Tropsch reaction.

Effect of water on liquid phase DME synthesis from syngas over hybrid catalysts composed of Cu/ZnO/Al2O3 and γ-Al2O3

DME synthesis from syngas via methanol has been carried out in a single-stage liquid phase reactor. Cu/ ZnO/Al2O3 and γ-Al2O3 were used together as methanol synthesis catalyst and dehydration catalyst, respectively. The influence of water on the catalytic system was investigated mainly. Water affected the activity of methanol dehydration catalyst as well as methanol synthesis catalyst. Thus, removal of water from the reaction system, by adding a dehydrating agent or controlling methanol formation rate by the reaction parameters, was efficient in maintaining the high catalytic activity and stability.

Mass- and heat-transfer-enhanced catalyst system for Fischer-Tropsch synthesis in fixed-bed reactors

Fischer-Tropsch synthesis (FTS) was carried out using Al2O3-supported Co catalyst coated on metallic monolith. Considering the liberation of a large amont of heat from the highly exothermic FTS reaction, catalytic activity of Co catalyst coated on metallic monolith was tested and compared with that of pellet-type catalysts. The reaction was carried out in a conventional tubular fixed-bed reactor and simulated distillation (SIMDIS) analysis method was used to determine the liquid products distribution. Proper control of degree of reaction, as well as the reaction temperature gave rise to a shift of products selectivity toward higher hydrocarbons, especially C13−C18 diesel range hydrocarbons.

Economic evaluations of direct, indirect and hybrid coal liquefaction

The various geopolitical problems associated with oil have rekindled interest in coal, with many countries working on projects for its liquefaction. This study established the feasibility of coal liquefaction through a technical and economic examination of direct coal liquefaction (DCL), indirect coal liquefaction (ICL) and hybrid coal liquefaction (HCL) processes. An economic efficiency analysis was prepared involving costs of initial investment, annual operating and raw coal purchase and revenues from the sale of major products as key variables. For the raw materials, products and investments, analyses of net present value (NPV), internal rate of return (IRR) and sensitivity were carried out. The processes’ IRRs were found to be 22.26% (DCL), 18.43% (ICL) and 20.90% (HCL). NPVs were

Cs promoted Fe5C2/charcoal nanocatalysts for sustainable liquid fuel production

4.720m (DCL),

Effects of SiO 2 Incorporation Sequence on the Catalytic Properties of Iron-Based Fischer-Tropsch Catalysts Containing Residual Sodium

3.811 m (ICL) and

Robust iron-carbide nanoparticles supported on alumina for sustainable production of gasoline-range hydrocarbons

4.254 m (HCL), and payback periods were DCL 3.3 years, ICL 4.2 years, and HCL 3.6 years. As a result of the sensitivity analysis, factors greatly affecting the earning potential of coal liquefaction included product prices, raw coal prices, and construction costs, which showed similar effects in each process.

Preparation of LaCoO3 with high surface area for catalytic combustion by spray-freezing/freeze-drying method

Cs promoted Fe5C2/charcoal nanocatalysts bearing small iron carbide particles of 8.5 and 14 nm were prepared through a simple melt-infiltration process and a wetness impregnation method; the resulting materials showed very high CO conversion (>95%) and good selectivity, especially at Cs/Fe = 0.025, resulting in a high liquid oil productivity (∼0.4 gliq gcat−1 h−1) in high-temperature Fischer–Tropsch synthesis.

Large-scale synthesis of uniformly loaded cobalt nanoparticles on alumina for efficient clean fuel production

Fischer–Tropsch synthesis was carried out over industrially important Fe/Cu/K/SiO2 catalysts containing a small amount of residual sodium which originated from the sodium carbonate solution used as a precipitating agent. The structural promoter, SiO2, was incorporated by two comparative sequences: immediately after precipitation (AP) or after a subsequent wash (AW). Whereas AW exhibited severe deactivation during the reaction, AP displayed high and stable catalytic activity for the entire reaction time. Furthermore, AP showed higher selectivity of liquid hydrocarbons, in particular heavy hydrocarbons, than AW. We attribute the advantageous catalytic performance observed in AP to the enhanced reducibility and higher surface basicity of AP, potentially induced by higher dispersion of catalysts and promoters.Graphical Abstract

Synthesis of Co/SiO2 hybrid nanocatalyst via twisted Co3Si2O5(OH)4 nanosheets for high-temperature Fischer–Tropsch reaction

The high-temperature Fischer–Tropsch synthesis reaction has been exploited to selectively produce lower-olefins and gasoline-range hydrocarbons (C5–C12) from a mixture of carbon monoxide and hydrogen, using iron-based catalysts. For this reaction, improving the selectivity and stability of the catalyst has been a major challenge, as has enhancing the activity. In the present work, we introduce iron-carbide nanoparticles supported on a porous gamma-alumina framework as a robust catalyst, prepared via a simple melt infiltration process and subsequent thermal treatment, for high-temperature Fischer–Tropsch synthesis. The iron-carbide/alumina catalyst showed much better catalytic performance, with a higher stability for producing gasoline-range hydrocarbon products, than did iron-carbide/mesoporous silica (SBA-15) and iron-carbide/activated carbon (AC).