Activation of Cobalt Foil Catalysts for CO Hydrogenation

CO hydrogenation has been studied on cobalt foils as model catalysts for Fischer–Tropsch (FT) synthesis. The effect of pretreatment (number of calcinations and different reduction times) for cobalt foil catalysts at 220 °C, 1 bar, and H2/CO = 3 has been studied in a microreactor. The foils were examined by scanning electron microscopy (SEM). It was found that the catalytic activity of the cobalt foil increases with the number of pretreatments. The mechanism is likely an increase in the available cobalt surface area from progressively deeper oxidation of the foil, supported by surface roughness detected by SEM. The highest FT activity was obtained using a reduction time of only 5 min (compared to 1 and 30 min). Prolonged reduction caused the sintering of cobalt crystallites, while too short of a reduction time led to incomplete reduction and small crystallites susceptible to low turn-over frequency from structure sensitivity. Larger crystals from longer reduction times gave increased selectivity to heavier components. The paraffin/olefin ratio increased with the increasing number of pretreatments due to olefin hydrogenation favored by enhanced cobalt site density. From the results, it is suggested that olefin hydrogenation is not structure sensitive, and that mass transfer limitations may occur depending on the pretreatment procedure. Produced water did not influence the results for the low conversions experienced in the present study (<6%).

The Potential Use of Raw Iron Ore in Fischer-Tropsch Synthesis

Fischer-Tropsch (FT) synthesis has been studied in the literature as a greener pathway to cleaner and sustainable hydrocarbons production. However, the cost to upscale laboratory FT formulations to pilot scale is significantly expensive. This work proposes a cheaper and scalable low-temperature FT modified iron ore catalyst that is mechanically suited for fixed bed reactors. The mechanical strength reported in this investigation was three times more than commercial alumina spherical pellets and, therefore, suitable for pilot scale scenarios. A manufacturing cost analysis of iron ore was estimated to be US$38.45/kg using the CatCost model, and the conventionally prepared iron catalyst was US$71.44/kg using the same model. The manufacturing cost estimations of modified iron ore were found to be 46% cheaper than a conventional commercial iron catalyst. The catalytic performance of the modified iron ore catalyst showed a CO conversion of 72.1% ±4.24, with WGS and C5+ selectivity 48.6% ±1.96 and 83.2% ± 5.24, respectively. These findings were comparable (both in CO conversion and product selectivity) to the ones reported by other researchers.

Fischer-Tropsch synthesis using carbon dioxide, water and electricity

The Fischer-Tropsch (FT) synthesis of fuels from CO and H2 lies at the heart of the successful and mature Gas-to-Liquid technology; however its reliance on fossil resources comes with the burden of an undesirable carbon footprint. In contrast, the electroreduction of CO2 (CO2RR) powered by renewable electricity has the potential to produce the same type of fuels, but in a carbon-neutral fashion. To date, only ethylene and ethanol are attainable at reasonable efficiencies and exclusively on copper. Herein, we report that the oxygenated compounds of nickel can selectively electroreduce CO2 to C1 – C6 hydrocarbons with significant yields (Faradaic efficiencies of C3+ up to 6.5%). While metallic Ni only produces hydrogen and methane under CO2RR and FT conditions respectively, we show that polarized nickel (Niδ+) sites facilitate ambient CO2RR via the FT mechanism. The catalysts yield multi-carbon molecules with an unprecedented chain growth probability values (α) up to 0.44, which matches many technical FT synthesis systems. We anticipate that the integration of the herein proposed electrochemical-FT scheme with fuel cells may provide at this seminal stage up to 7% energy efficiency for C3+ hydrocarbons, inaugurating a new era towards the defossilization of the chemical industry.

The Application of Dielectric Barrier Discharge Plasma on Fischer-Tropsch Synthesis: A Review

Fischer-Tropsch (FT) Synthesis has been widely known for centuries as the process of converting syngas to liquid fuels. Several reactors including Slurry bubble column, fluidized-bed, and fixed bed reactors have been used for FTS on an industrial scale. Although science has seen remarkable development in technology for FT synthesis, the industry still faces challenges in optimizations of process parameters and achieved desired selectivity. Extensive research has been continuously conducted to seek the best FT reactor offering heat uniformity and efficient heat transfer across the reactor to increase the catalytic activity and its lifetime. Dielectric Barrier Discharge (DBD) plasma has become one of the options to deal with these issues. This reactor work under low temperature delivers a synergistic effect between plasma and catalyst to break H2 and CO bond. DBD plasma is also suitable for feedstock with high H2/CO molar ratios. It is also found that FT catalyst such as cobalt catalyst used in DBD plasma was well dispersed on the support which in turn favour the selectivity toward liquid hydrocarbon.

Fischer–Tropsch synthesis over Pd promoted cobalt based mesoporous supported catalyst

The present study focuses on the catalytic conversion of syngas (CO + H2) through Fischer–Tropsch (FT) route using two identically prepared 0.1 wt.% palladium promoted Mesoporous Alumina (MA) and SBA–15 supported Co (15 wt.%) catalysts. The Fischer–Tropsch activity is performed in a fixed bed tubular reactor at temperature 220 °C and pressure 30 bar with H2/CO ratio ~2 having Gas Hourly Space Velocity (GHSV) of 500 h−1. Detail characterizations of the catalysts are carried out using different analytical techniques like N2 adsorption-desorption, Temperature-programmed reduction with hydrogen (H2-TPR), Temperature-programmed desorption with NH3 (NH3-TPD), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (TEM). The results show that the SBA–15 supported catalyst exhibits higher C6–C12 selectivity (57.5%), and MA supported catalyst facilitates the formation of higher hydrocarbons (C13–C20) having a selectivity of 46.7%. This study attributes the use of both the support materials for the production of liquid hydrocarbons through FT synthesis.

Innovation in Fischer-Tropsch: A Sustainable Approach to Fuels Production

A sustained global effort is required over the next few decades to reduce greenhouse gas emissions, in order to address global warming as society seeks to deliver the Paris Agreement temperature goals. The increasing availability of renewable electricity will reduce our reliance on fossil fuels. However, some applications, such as long-haul aviation, are particularly challenging to de-carbonise. The conversion of waste, biomass or existing CO2 emissions into sustainable fuels via FT synthesis offers one solution to this problem. This paper describes some of the challenges associated with this route to these alternative fuels and how Johnson Matthey and bp have solved them.

Stabilization of ε-iron carbide as high-temperature catalyst under realistic Fischer–Tropsch synthesis conditions

The development of efficient catalysts for Fischer–Tropsch (FT) synthesis, a core reaction in the utilization of non-petroleum carbon resources to supply energy and chemicals, has attracted much recent attention. ε-Iron carbide (ε-Fe2C) was proposed as the most active iron phase for FT synthesis, but this phase is generally unstable under realistic FT reaction conditions (> 523 K). Here, we succeed in stabilizing pure-phase ε-Fe2C nanocrystals by confining them into graphene layers and obtain an iron-time yield of 1258 μmolCO gFe−1s−1 under realistic FT synthesis conditions, one order of magnitude higher than that of the conventional carbon-supported Fe catalyst. The ε-Fe2C@graphene catalyst is stable at least for 400 h under high-temperature conditions. Density functional theory (DFT) calculations reveal the feasible formation of ε-Fe2C by carburization of α-Fe precursor through interfacial interactions of ε-Fe2C@graphene. This work provides a promising strategy to design highly active and stable Fe-based FT catalysts.

Impact of Coordination Features of Co(II)-Glycine Complex on the Surface Sites of Co/SiO2 for Fischer–Tropsch Synthesis

To investigate the effect of coordination features of Co(II)-glycine complex on the performance of Co/SiO2 for Fischer–Tropsch (FT) synthesis, Co(II)-glycine complex precursors were prepared by the conventional method, i.e., simply adding glycine to the solution of Co nitrate and novel route, i.e., reaction of glycine with cobalt hydroxide. The SiO2-supported Co catalysts were prepared by using the different Co(II)-glycine complexes. It is found that glycine is an effective chelating agent for improving the dispersion of Co and the mass-specific activity in FT synthesis when the molar ratio of glycine/Co2+ = 3, which is independent to the preparation method in this study. Significantly, the surface Co properties were significantly influenced by the coordination features of the Co2+ and the molar ratio of glycine to Co2+ in the Co(II)-glycine complex. Specifically, the Co(3gly)/SiO2 catalyst prepared by the novel route exhibits smaller and homogenous Co nanoparticles, which result in improved stability compared to Co-3gly/SiO2 prepared by the conventional method. Thus, the newly developed method is more controllable and promising for the synthesis of Co-based catalysts for FT synthesis.

Preparation of Synthesis Gas from CO2 for Fischer–Tropsch Synthesis—Comparison of Alternative Process Configurations

We compare different approaches for the preparation of carbon monoxide-rich synthesis gas (syngas) for Fischer–Tropsch (FT) synthesis from carbon dioxide (CO2) using a self-consistent design and process simulation framework. Three alternative methods for suppling heat to the syngas preparation step are investigated, namely: allothermal from combustion (COMB), autothermal from partial oxidation (POX) and autothermal from electric resistance (ER) heating. In addition, two alternative design approaches for the syngas preparation step are investigated, namely: once-through (OT) and recycle (RC). The combination of these alternatives gives six basic configurations, each characterized by distinctive plant designs that have been individually modelled and analyzed. Carbon efficiencies (from CO2 to FT syncrude) are 50–55% for the OT designs and 65–89% for the RC designs, depending on the heat supply method. Thermal efficiencies (from electricity to FT syncrude) are 33–41% for configurations when using low temperature electrolyzer, and 48–59% when using high temperature electrolyzer. Of the RC designs, both the highest carbon efficiency and thermal efficiency was observed for the ER configuration, followed by POX and COMB configurations.