Graphene-Supported, Iron-Based Nanoparticles for Catalytic Production of Liquid Hydrocarbons from Synthesis Gas: The Role of the Graphene Support in Comparison with Carbon Nanotubes

Abstract

Fischer−Tropsch synthesis (FTS) is a potentially attractive technology for the production of clean liquid fuels from synthesis gas. The efficiency and selectivity of FTS can be enhanced by the design of new active catalyst systems with improved selectivity for long-chain hydrocarbons and low methane production. In this paper, we introduce a new class of FT catalysts supported on the high surface area graphene nanosheets and report on their high activity and selectivity for the production of long-chain hydrocarbons. The chemical reduction of graphene oxide in water in the presence of the metal salts under microwave irradiation allows the deposition of well-dispersed surface-oxidized metal nanoparticles on the defect sites of the graphene nanosheets. The Fe−K-nanoparticle catalyst supported on graphene exhibits high activity and selectivity toward C 8 and higher hydrocarbons with excellent stability and recyclability. In comparison with other carbon supports, such as carbon nanotubes, the graphene support shows a unique tendency for minor formation of the low-value and undesirable products methane and carbon dioxide, respectively. The water-gas shift activity is reduced on the graphene support as compared with CNTs, and as a result, the formation of CO 2 is significantly reduced. Evidence is presented for the formation of the active Fe 5 C 2 iron carbide phase during the FTS on the graphenesupported Fe catalysts. The high activity and selectivity of the catalysts supported on graphene are correlated with the presence of defects within the graphene lattice that act as favorable nucleation sites to anchor the metal nanoparticles, thus providing tunable metal−support interactions. Given the activity, selectivity, and stability of the new graphene-supported, Fe-based nanoparticle catalysts, their industrial application appears to be promising. Controlling the nature and density of the defect sites in graphene could lead to improved understanding of the catalyst−graphene interactions and to further enhancement of the performance of these catalysts for the production of liquid fuels.

On the structural, textural and morphological features of Fe-based catalysts supported on polystyrene mesoporous carbon for Fischer–Tropsch synthesis

“…The overall performance of the non-promoted Fe-PMC catalyst was similar to the performance of catalysts with the presence of the K and Mn promoters [13]. The enhanced formation of long-chain hydrocarbons may be related to the support and the presence of iron carbides, which may be suppressing the formation of methane and shifting the product selectivity to higher-molecular-weight hydrocarbons (C 5+ ).…”

“…Silica, alumina, molecular sieves, titania, zirconia, carbon and zeolites have been the most studied supports for FTS catalysts [1][2][3][4][5][6][7][8][9][10][11]. Iron forms mixed oxides when supported on silica or alumina due to the influence of strong metal−support interactions, which are difficult to reduce and to allow the formation of the active Fe carbide [12][13][14][15].…”

“…Therefore, porous carbon materials appear to be good candidates to be applied as support for FTS due to their high chemical stability, good thermal conductivity, and weak metal-carbon interaction [12]. Carbon supports such as nanotubes, spheres, nanowires, active carbon were also reported to be less sensitive to deactivation compared to silica supported FTS catalysts [13][14][15][16][17][18][19][20].…”

Two-dimensional collagen-graphene as colloidal templates for biocompatible inorganic nanomaterial synthesis

“…4 Two-dimensional graphene anchors both metallic and non-metallic particles alike because of the defects introduced during its formation from the parent graphite (GR). 5,6 Direct exfoliation of GR to graphene has been attempted by many, but is yet to be fool proofed.…”

Effect of the Size of Iron Nanoparticles on the Catalytic Activity and Selectivity of Fe/Cnt Nanocomposites in Hydrogenolysis of Ethylene

“…At the present time catalysts with deposited nanoparticles of iron are being actively investigated in hydrogenation processes [6]. Study of the dependence of the effect of the size of the iron nanoparticles on the catalytic activity and selectivity of nanocomposites containing such nanoparticles are of both theoretical and practical interest in view of the fact that the establishment of such relationships may lead to the creation of novel catalytic systems with controllable activity and selectivity [7,8].…”