Preparation of an Unsupported Iron Fischer–Tropsch Catalyst by a Simple, Novel, Solvent-Deficient Precipitation (SDP) Method

Abstract

Recent breakthroughs in the preparation of transition metal oxide nanoparticles by solvent-deficient precipitation (SDP) provide exciting new possibilities for simpler and faster methods to prepare heterogeneous catalysts with small uniformly sized crystallites of the active phase. In this study, the authors apply the SDP method to prepare an unsupported iron Fischer− Tropsch (FT) catalyst with a nominal composition of 100 Fe/5 Cu/4 K/16 SiO 2 (relative mass) and an average crystallite size of 10−11 nm. Three preparations of this catalyst were made using SDP, and each was tested for over 200 h in a fixed-bed reactor to determine activity, selectivity, and stability. Values of the apparent first-order rate constants for syngas consumption at 260 °C were 215−251 mmol g Fe −1 h −1 MPa −1 for our catalyst compared to 155−265 mmol g Fe −1 h −1 MPa −1 for literature catalysts not using a proprietary pretreatment (Bukur, D. B.; Lang, X. Ind. Eng. Chem. Res. 1999, 38, 3270−3275). Our catalyst was tested for more than 500 h and showed little or no downward trend with time, suggesting that the SDP method produces FT catalysts with not only high activity, competitive with the best reported in the literature, but also promising stability.

Review on Carbon Dioxide Absorption by Choline Chloride/Urea Deep Eutectic Solvents

“…Moreover, the thermal stability of choline-based DES was studied by Rengstl et al [18] who reported that the decomposition temperature of these solvents is in the range of 269-290 ∘ C which is higher than those reported for ionic liquids [11]. …”

“…This is because this mixture has the lowest melting point reported when it is in the ratio 1 choline chloride : 2 urea and has shown high CO 2 absorption capacity at mild conditions [11]. Moreover, we shall summarize the factors that affect CO 2 solubility in this DES and what makes it as a promising solvent for CO 2 capture via absorption technologies.…”

Effect of Drying Temperature on Iron Fischer-Tropsch Catalysts Prepared by Solvent Deficient Precipitation

“…The combined mixture of dry powders was vigorously mixed with the pestle, during which waters of hydration were released to produce a liquid slurry. Mixing continued for approximately 20 minutes until precipitation of a paste of Fe and Cu hydroxides, referred to as the precursor catalyst, was complete as indicated by cessation of CO 2 release as bubbles [18].…”

“…Recently, a novel, solvent deficient method for creating nanoparticles was discovered by the BYU Department of Chemistry and Biochemistry and Cosmas, Inc. [15][16][17]. Brunner et al extended this method to prepare an iron heterogeneous catalyst for Fischer-Tropsch synthesis that is known as the solvent deficient precipitation (SDP) method [18]. Iron catalysts prepared by the SDP method produce a substantial amount of ammonium nitrate (NH 4 NO 3 ) as a byproduct of the reaction.…”

Iron Fischer-Tropsch Catalysts Prepared by Solvent-Deficient Precipitation (SDP): Effects of Washing, Promoter Addition Step, and Drying Temperature

“…To the best of our knowledge, the Cosmas SDP method had never been used for preparation of a catalyst prior to our current work. A report describing the preparation and performance of one Fe FT catalyst using the SDP method was published earlier this year [22]. It was also the subject of a dissertation [23].…”