Adjusting hydrocarbon product distributions in the Fischer–Tropsch (FT) synthesis is of notable significance context so-called X-to-liquids (XTL) technologies. While cobalt catalysts are selective to long-chain paraffin precursors for synthetic jet- and diesel-fuels, lighter (C10–) alkane condensates less valuable fuel production. Alternatively, iron carbide-based suitable coproduction paraffinic waxes alongside liquid (and gaseous) olefin chemicals; however, their activity water–gas-shift...

Atomic carbon on Co(0001), deposited by ethylene decomposition, forms islands with a (√3 × √3)R30° structure at low C coverage (∼0.2 ML), whereas high (0.5 ML, saturation) induces reconstruction of the cobalt surface. weakens adsorption CO and H2, but even saturated atomic layer does not block surface for adsorption. Carbon–carbon coupling, i.e., polymeric formation, was observed temperatures ≤630 K close-packed Polymeric carbon, in form small graphene islands, terraces after heating an...

Oxygen adsorption and removal on flat defective Co(0001) surfaces have been investigated experimentally using scanning tunneling microscopy, temperature-programmed isothermal reduction, synchrotron X-ray photoemission spectroscopy, work function measurements under ultrahigh vacuum conditions H2/CO pressures in the 10–5 mbar regime. Exposure of to O2(g) at 250 K leads formation p(2 × 2) islands with a local coverage 0.25 ML. continues beyond ML, reaching saturation point ∼0.39 ML Oad, without...

We present here the synthesis and performance of dual-atom catalysts (DACs), analogous to well-known single-atom (SACs). DACs feature sites containing pairs metal atoms can outperform SACs due their additional binding possibilities. Yet quantifying improved catalytic activity in terms proximity effects remains difficult, as it requires both high-resolution kinetic data an understanding reaction pathways. Here, we use automated bubble counter setup for comparing ceria-supported platinum...

In order to fundamentally understand cobalt catalyst deactivation in Fischer–Tropsch synthesis (FTS) due parts per million levels of NH3 the gas, adsorption and decomposition on Co(0001) are investigated experimentally under ultrahigh vacuum (UHV) conditions theoretically using density functional theory (DFT) calculations. desorbs intact from surface, between 100 270 K. agreement with this, DFT calculations show that activation barrier for decomposition, 105 kJ/mol, is higher than energy...

LEED, TPRS, and RAIRS experiments combined with DFT calculations have been used to study CO oxidation on Rh(100) from preadsorbed O unravel how the reaction kinetics is influenced by configuration of adsorbed reactants. At least four different regimes are identified in increasing order reactivity: near zero coverage, isolated species react highest activation energy observed this work (105 ± 4 kJ/mol). In second regime, oxygen present a p(2 × 2) structure reacts bridge bonded CO, an 77 8...

Formation of carbon dioxide from preadsorbed O and CO has been modeled by Density Functional Theory (DFT) calculations on Rh(100) Rh(111) for total surface coverages 0.22, 0.50, 0.66, 0.75 ML. The most stable coadsorption configurations are investigated each case prior to the modeling reaction. It is seen that activation barriers continuously decrease (from 1.03 0.40 eV) with increasing coverage, due always leading less strongly bound adsorbates. On Rh(111), however, remain relatively...

Sulfur is a common poison for cobalt-catalyzed Fischer–Tropsch Synthesis (FTS). Although its effects on catalytic activity are well documented, selectivity controversial. Here, we investigated the of sulfur-covered cobalt surfaces FTS using density functional theory (DFT) calculations. Our results indicated that sulfur surface Co(111) resulted in significant decrease adsorption energies CO, HCO and acetylene, while binding H CH species were not significantly affected. These findings indicate...

The present article aims to show how work function measurements (WF) can be applied in the study of elementary surface reaction steps on metallic single crystal surfaces. itself many cases not interpreted directly, as it lacks direct information structural and chemical nature adsorbates, but a powerful tool when used together with other science techniques which provide adsorbed species. We here, illustrate usefulness using Rh(100) our model catalyst. examples presented include during...

Undercoordinated (defect) sites on cobalt surfaces favor NH₃ decomposition and dehydrogenated products adsorb strongly around these defect sites.

The conversion of carbon dioxide to fuels and chemicals is a promising long-term approach for mitigating CO2 emissions. Despite extensive experimental efforts, fundamental understanding the bimetallic catalytic structures that selectively produce desired products still lacking. Here, we report on computational surface science into effect Fe doping Co(111) surfaces in relation hydrogenation C1 products. Our results indicate increases binding strength species but slightly decreases overall...

The effect of boron promotion on atomic sulfur formation by hydrogen sulfide dissociation Co(111), flat surfaces cobalt nanoparticles, was investigated using Density Functional Theory calculations. results show that clean proceeds fast due to low activation barriers, yielding the surfaces. Boron hinders increased barriers. Furthermore, prevents interaction compounds with surface atoms, as these poisons bind boron. findings indicate is an effective promoter can be used design resistant catalysts.