Effect of Pt Impregnation on a Precipitated Iron-based Fischer–Tropsch Synthesis Catalyst

Abstract

Effect of Pt impregnation on the textural properties, surface element distributions and catalytic behavior of a precipitated iron-based catalyst for FischerTropsch synthesis (FTS) was investigated by N 2 physical adsorption, temperature-programmed reduction (TPR), Mössbauer effect spectrometer (MES), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM). Low levels of Pt addition lead to an increase in BET surface area. The result of XPS indicates that Pt enriches on the catalyst surface after being calcined. HRTEM shows that Pt crystallites with diameter about 2 nm are well dispersed on the surface of the catalyst (100Fe/1Pt/4 K/16SiO 2 ). The results of TPR and MES clearly indicate that Pt facilitates the reduction and carburization of Fe 2 O 3 to some extend. The reaction tests in a slurry reactor give the result that the Pt impregnation remarkably increases the FTS activity, and suppresses the selectivities of the light hydrocarbons and the olefins.

Catalytic activity of Fe/ZrO2 nanoparticles for dimethyl sulfide oxidation

“…The first stage can be further divided into two peaks: the first peak corresponds to the reduction of Fe 2 O 3 to Fe 3 O 4 , and the second peak corresponds to subsequent reductions of Fe 3 O 4 to FeO. The reduction temperature for both catalysts is in line with the observations of those reported in literature [44][45][46].…”

Environmental transmission electron microscopy investigations of Pt-Fe2O3 nanoparticles for nucleating carbon nanotubes

“…The Pt promotes the reduction and carburization of Fe2O3 by a spillover effect, facilitating the formation of carbon-rich Fe2.5C. [8,17] The finding is consistent with that of Yu et al [17] who studied the effect of Pt on a Fe-based Fischer-Tropsch catalyst. However, it is noted that with long enough 11 reaction time (1 h), the catalyst evolved into single-crystalline PtFe alloy phase (ESI Figure S8), in agreement with ex situ TEM investigations (Figure 2).…”

“…[20][21][22] Different from monometallic Fe catalyst, in our PtFe catalyst, Fe tends to form Hägg carbide (Fe2.5C) phase in the presence of CO, which could be related to the presence of Pt. [8,17] As discussed by Wei et al, [18] Fe2.5C can be stabilized under high carbon chemical potential at temperatures resembling our reaction conditions. The Pt promotes the reduction and carburization of Fe2O3 by a spillover effect, facilitating the formation of carbon-rich Fe2.5C.…”

“…In CO hydrogenation, the addition of Pt substantially improves the reducibility of Fe2O3, [17] which can be ascribed to the spillover effect of reductive species on Pt. Similarly, the improved reducibility of Fe2O3 in the presence of Pt is of great importance for nucleation and growth of carbon nanotubes, as reduction of Fe2O3 is a prerequisite for catalytic dissociation of carbon source and dissolution of carbon atoms.…”

“…The formation of small-diameter SWCNTs from large-size catalyst particle is attributed to selective nucleation on small-diameter particles and the perpendicular growth mode when using CO as the carbon source, [25,30] as demonstrated in Figure 2. Chiral map of SWCNTs without 7 large diameter ones, namely, (24,6), (17,15), (14,13), (28,6), (16,12), . There is no high selectivity to certain (n, m) species, but (8,4), (7,6), (8,6), (9, 7), (9,8) and (10,6) tubes occupy more than 37% of the total.…”