Effect of K promoter on the structure and catalytic behavior of supported iron-based catalysts in fischer-tropsch synthesis

Abstract

-Effects of K addition on the performance of supported Fe catalysts for Fischer-Tropsch synthesis (FTS) were studied in a slurry reactor at 240 to 270°C, 2.0 to 4.0 MPa and syngas H 2 /CO = 1.0. The catalysts were characterized by N 2 adsorption, H 2 temperature programmed reduction, X-ray diffraction, X-ray fluorescence, thermogravimetric analysis, scanning electron microscopy and dispersive X-ray spectroscopy. A strong interaction was observed between Fe and K, which inhibited the reduction of Fe catalyst. Addition of potassium increased the production of heavy hydrocarbons (C20+).

Fe/γ-Al2O3and Fe–K/γ-Al2O3as reverse water-gas shift catalysts

“…3,4 The second WGS reactor is operated at "low temperature" (453-523 K) and uses Cu-Zn/ Al 2 O 3 as the catalyst. 5 In addition to WGS, supported iron is known to catalyze the RWGS reaction 6 and a number of other industrially important reactions, including: i) Fischer-Tropsch synthesis, 7 ii) ammonia synthesis, 8 iii) ethylbenzene dehydrogenation to styrene, 9 and iv) selective catalytic reduction of nitrogen oxides (NO x ) with ethanol (EtOH-SCR). 10 The RWGS and WGS reactions are often carried out in conjunction with Fischer-Tropsch synthesis on iron catalysts, 11 in which case iron carbide is believed to be the active phase for hydrocarbon production, 12 and iron oxide is the active phase for WGS and RWGS.…”

Investigation of Mn and Ca promoter effects in iron-based catalysts: CO hydrogenation reaction

“…This decrease may be due to the formation of larger hematite crystals. 39,43,44 The reduction in the specific surface area, pore volume and average pore size of the catalysts' values because of metal loading, indicates that Fe and Cu were effectively introduced into the catalysts' porous structure. The similar tendency was reported by Pen ˜a et al, revealing that Cu species could be partially covering the mesoporous structure of the alumina support.…”

“…This is because these promoters help to improve the dispersion and inhibit the agglomeration of iron atoms 45 and may be due to the formation of larger hematite crystals. 39,43,44 Fig. 3 shows the nitrogen physical adsorption-desorption isotherms of the (a), (b), (c) and (d) catalysts.…”

“…This is because these promoters help to improve the dispersion and inhibit the agglomeration of iron atoms 45 and may be due to the formation of larger hematite crystals. 39,43,44…”

The role of zeolites in the deactivation of multifunctional fischer-tropsch synthesis catalysts: the interaction between HZSM-5 and Fe-based Ft-catalysts

“…Figure 1 shows the CO conversion over FT-Ru and FT-K catalysts and the physical mixtures of these catalysts with HZSM-5 in the FTS. The Kpromoted catalyst (FT-K) exhibits higher activity than that promoted by Ru (FT-Ru), (Farias et al, 2011). Both physical mixtures show a very low CO conversion, suggesting that HZSM-5 promotes a decrease of the activity of the FT-catalysts.…”