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

Abstract

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.

The Use of Iron Ore as a Catalyst in Fischer–Tropsch Synthesis—A Review

“…Fischer-Tropsch synthesis (FTS) is an established technology that has been around for almost 100 years and is commercially spearheaded by renowned companies such as Sasol, Shell, and Synfuels China. The process involves the catalytic conversion of syngas (i.e., a mixture of CO and H 2 ) derived from natural gas, coal, and biomass into valuable hydrocarbon products such as gasoline, diesel, lubricants, and chemicals [1][2][3][4][5][6][7]. FTS relies on iron and cobalt as the catalysts to convert syngas into a myriad of hydrocarbons due to their economic competitiveness over other transition metals such as ruthenium, nickel, etc.…”

“…[4,6]. Among cobalt and iron, the latter is favored for FTS due to its cost, availability, and compatibility with hydrogen deficient feedstocks such as coal and biomass [1,2,8,9]. Moreover, its compatibility with biomass is attractive because it provides the opportunity to produce cleaner fuels with no sulfur, nitrogen, or aromatics as pollutants [2,[9][10][11][12].…”

“…Nevertheless, biomass-to-liquid Fischer-Tropsch (BTL-FT) technology is still relatively more expensive to implement on a large scale compared to coal-to-liquid Fischer-Tropsch (CTL-FT) and gas-to-liquid Fischer-Tropsch (GTL-FT) technologies [9,[13][14][15][16]. One of the ways to address this issue is to substitute conventional iron catalysts with cheaper iron ore [1][2][3]6,7,17]. Precipitated iron catalyst is one of the conventional iron-based catalysts used in FTS [4], and it requires the use of various chemicals for its preparation, which increases its cost [1][2][3][4][5][6].…”

“…One of the ways to address this issue is to substitute conventional iron catalysts with cheaper iron ore [1][2][3]6,7,17]. Precipitated iron catalyst is one of the conventional iron-based catalysts used in FTS [4], and it requires the use of various chemicals for its preparation, which increases its cost [1][2][3][4][5][6]. On the other hand, iron ore is a source of iron, and the use of iron ore as a catalyst for FTS is fast gaining the attention of researchers due to its natural abundance and low price [1][2][3]6,7,17].…”

“…The FT catalytic performance of any catalytic material is directly linked to its properties, which rely on the catalyst synthesis method and precursor chosen from the begi-nning [3,9,10,[18][19][20]. Thus, an optimized catalyst design and development process must be in place to achieve an excellent performing catalyst [1,3,16,[19][20][21][22][23][24][25]. It is imperative to have an optimized catalyst to make the overall FT application economical for the practitioner by ensuring high production of the desired hydrocarbons [3,10,16,20,25].…”