A study of the effects of potassium addition to supported iron catalysts in the Fischer-Tropsch reaction

Abstract

The Fischer-Tropsch activity of supported iron catalysts prepared via electrochemical techniques has been evaluated as a function of potassium addition. Catalyst pretreatment in 0.09, 0.18, and 0.27 M K2C03 solutions generated potassium levels of 1.7, 2.8, and 3.9 wt %, respectively. Pretreatment in 0.18 KOH provided a catalyst with 2.3 wt % potassium and facilitated comparison of the effects of the basicity of the pretreatment solution upon catalyst activity. A maximum in catalyst activity and CO conversion was noted upon increasing K content, followed by a sharp decline in activity at potassium levels in excess of the maximum. The hydrogenation ability of the catalyst decreased, and a shift to higher molecular weight products was observed, with increasing potassium content. The type of pretreatment solution had little effect on the catalyst activity or the product selectivity.

FeN particles confined inside CNT for light olefin synthesis from syngas: Effects of Mn and K additives

“…But an excessive amount can retard the carburization of iron during reaction, which was considered to be essential to achieve a high activity due to enrichment of manganese on the catalyst surface [15,[18][19][20][21]. The effects of potassium promotion on the catalytic behavior of iron-based FTS catalysts have also been extensively investigated [16,[22][23][24][25]. An appropriate amount of potassium improved the catalytic activity, but the activity of the catalysts declined with the addition of an excess amount [16,[23][24][25].…”

“…The effects of potassium promotion on the catalytic behavior of iron-based FTS catalysts have also been extensively investigated [16,[22][23][24][25]. An appropriate amount of potassium improved the catalytic activity, but the activity of the catalysts declined with the addition of an excess amount [16,[23][24][25]. Formation of olefins and long chain hydrocarbons, and the carburization of surface Fe were usually facilitated while CH 4 formation was suppressed [22][23][24][25].…”

“…An appropriate amount of potassium improved the catalytic activity, but the activity of the catalysts declined with the addition of an excess amount [16,[23][24][25]. Formation of olefins and long chain hydrocarbons, and the carburization of surface Fe were usually facilitated while CH 4 formation was suppressed [22][23][24][25]. Following these earlier studies, we investigate the effects of manganese and potassium promoters on the structure and the catalytic performance of FeN nanoparticles confined in CNTs for light olefin synthesis from syngas.…”

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

“…The use of promoters in iron-based catalysts enhances both selectivity and activity of the catalyst. Attempts to enhance fuel selectivity were studied by adding chemical and structural promoters, such as K (Miller and Moskovits, 1988;Yang et al, 2004;Farias et al, 2008), Cu (Bukur et al, 1990), Mn (Maiti et al, 1983(Maiti et al, , 1985Bai et al, 2002;Lohitharn and Goodwin Jr., 2008), Mo (Dun et al, 2985;Qin et al, 2009), Mg Pour et al, 2010), La (Pour et al, 2010), Ca (Pour et al, 2010) and zeolite (Botes and Böhringer, 2004;Martínez and López, 2005), into iron-based catalysts.…”

“…Potassium suppresses the production of methane and improves the effective hydrocarbon selectivity (Miller and Moskovits, 1988;Yang et al, 2004). The effect of potassium has been mostly studied in precipitated iron-based catalysts and fewer studies have reported its influence in supported iron-based catalysts.…”