In-silico investigations in heterogeneous catalysis—combustion and synthesis of small alkanes

Abstract

In this critical review, we cover first-principles density functional calculations relevant to alkane oxidation and synthesis over transition metal catalysts. For oxidation, we focus upon Pt, Rh, Pd and Ni surfaces, while for synthesis we consider Co, Ru, Fe and Ni. Throughout, we emphasise the insight to be gained by thinking of each kind of reaction as the inverse of the other, with the directionality determined simply by the choice of metal catalyst and the reaction conditions. We highlight particularly the role of low-coordination sites (steps, kinks, etc.) and the emerging consensus over the importance of the formyl intermediate in facilitating the rate-determining step (249 references).

CO Dissociation at Vacancy Sites on Hägg Iron Carbide: Direct Versus Hydrogen-Assisted Routes Investigated with DFT

“…Kinetic analysis of FT synthesis on ironbased catalysts is consistent with hydrogen-assisted CO dissociation [24], although the possibility of parallel direct and hydrogen-assisted paths has also been invoked [20]. Even within the hydrogen-assisted scheme, different intermediates can form [3,25,26], and in the context of FT synthesis, HCO [27][28][29][30][31], HCOH [20,21] and H 2 CO [30,32] have all been proposed as possible key intermediates on Ru and Co surfaces based on density functional theory (DFT) calculations, with COH as the key species in the methanation reaction on Ni surfaces [33]. From an experimental viewpoint, although spectroscopic evidence for formation of hydrogenated intermediates such as HCO and H 2 CO from CO and hydrogen has been obtained on Ru catalysts [34][35][36], unambiguous assignment was challenged by the fact that HCO species have been calculated to be unstable above 170 K [37].…”

“…The Fischer-Tropsch (FT) synthesis reaction is an attractive process not only because it can be used to make synthetic crude oil from coal or natural gas [1], but also because it represents a potential carbon-neutral route to the production of transportation fuels through the hydrogenation of carbon monoxide derived from biomass [2,3]. Although a number of transition metals (e.g.…”

Study of propane oxidation on Cu-zeolite catalysts by in-situ EPR and IR spectroscopies

“…Zeolite Y is commercially available (CBV 720, Zeolyst International). Prior to ion exchange, all zeolites were rinsed with a 0,04 M solution of NaNO 3 Table 1.…”

Fischer-Tropsch Synthesis on Multicomponent Catalysts: What Can We Learn from Computer Simulations?

“…Usually, only relatively small quantities of non-alkane products are formed, although catalysts favoring some of these byproducts have been also developed [12,13].…”

“…Not only Fe, Co and Ru are being considered in this quest for novel catalysts for the Fischer-Tropsch synthesis reaction. Other transition metals (and alloys of different metals) are being considered, especially those from group VIIIA in the Periodic Table because they display some activity in the C-C coupling reaction during CO hydrogenation [13,[16][17][18][19][20][21][22][23][24][25][26][27][28][29]. Yet, this is not a trivial task since small variations in the catalyst composition change dramatically the reaction yield and/or selectivity.…”