Al13Fe4 as a low-cost alternative for palladium in heterogeneous hydrogenation

Abstract

Replacing noble metals in heterogeneous catalysts by low-cost substitutes has driven scientific and industrial research for more than 100 years. Cheap and ubiquitous iron is especially desirable, because it does not bear potential health risks like, for example, nickel. To purify the ethylene feed for the production of polyethylene, the semi-hydrogenation of acetylene is applied (80 × 10(6) tons per annum; refs 1-3). The presence of small and separated transition-metal atom ensembles (so-called site-isolation), and the suppression of hydride formation are beneficial for the catalytic performance. Iron catalysts necessitate at least 50 bar and 100 °C for the hydrogenation of unsaturated C-C bonds, showing only limited selectivity towards semi-hydrogenation. Recent innovation in catalytic semi-hydrogenation is based on computational screening of substitutional alloys to identify promising metal combinations using scaling functions and the experimental realization of the site-isolation concept employing structurally well-ordered and in situ stable intermetallic compounds of Ga with Pd (refs 15-19). The stability enables a knowledge-based development by assigning the observed catalytic properties to the crystal and electronic structures of the intermetallic compounds. Following this approach, we identified the low-cost and environmentally benign intermetallic compound Al(13)Fe(4) as an active and selective semi-hydrogenation catalyst. This knowledge-based development might prove applicable to a wide range of heterogeneously catalysed reactions.

Combined Macro/Nanoscale Investigation of the Chemical Vapor Deposition of Fe from Fe(CO)5

“…As a result, the Fe(CO) 2 decomposition (Table 1, G4) and consequently the FeCO decomposition (Table 2, SR3) do not occur, since all Fe(CO) 2 intermediates are consumed in the recombination with CO to form Fe(CO) 3 . The recombination of Fe(CO) 4 with CO yields null rates, consistent to literature reports, [17] whereas the recombination of Fe(CO) 3 with CO occurs at negligible rates (≈10 −9 kmol m −3 s −1 ), due to the consumption of the tricarbonyl by the surface reaction (Table 2, SR2). Figure 3c shows the mass fractions of Fe(CO) 5 and Fe(CO) 3 at T s = 223 °C (black and red solid lines, respectively) and T s = 215 °C (black and red dashed lines, respectively), still 1 mm above the susceptor.…”

“…The same dependence of the deposition rate on the surface temperature is observed in the MOCVD of Ni from Ni(CO) 4 , [8,28] which belongs to the same family of carbonyl precursors.…”

“…[3] It was shown recently that the bulk Al 13 Fe 4 intermetallic alloy presents excellent catalytic activity which may be further improved if processed in the form of thin films. [4] Several methods have been developed for the production of Fe and Fe-containing thin films, among which chemical vapor deposition (CVD) that combines high deposition rates, moderate process temperatures, reduced effluents volume, and conformal coverage of complex surfaces.…”

The formation of (Al8Fe2Si, Al13Fe4) phases from Al-Fe-Si system by TE mode

“…Lattice images revealed that the Al 13 Fe 4 crystals are divided into tiny domains (few thousand pm) which are separated by lattice displacements such as stacking faults [22,14].This phase was also identified as an active and selective semi-hydrogenation catalyst [23].…”

Hydrogenation of Propyne Verifying the Harmony in Surface and Bulk Compositions for Fe-Ni Alloy Nanoparticles

“…To develop high-performance catalysts, alloying is often used to tune the properties or to create novel properties. [5][6][7][8][9][10][11][12] For industrial use, catalysts must be nanoparticulate to ensure high surface area. In base metal alloys, however, it is dif cult to synthesize nanoparticles via a liquid-phase route because the oxidationreduction potentials of their constituent elements are low.…”