We demonstrate a one-pot hydrothermal cohydrolysis-carbonization process using glucose and iron nitrate as starting materials for the fabrication of carbonaceous spheres embedded with iron oxide nanoparticles. It is verified by TEM, (57)Fe Mossbauer, and Fe K-edge XAS that iron oxide nanoparticles are highly dispersed in the carbonaceous spheres, leading to a unique microstructure. A formation mechanism is also proposed. This route is also applicable to a range of other naturally occurring saccharides and metal nitrates. A catalytic study revealed the remarkable stability and selectivity of the reduced Fe(x)O(y)@C spheres in the Fischer-Tropsch synthesis, which clearly exemplifies the promising application of such materials.

Amorphous alloys structurally deviate from crystalline materials in that they possess unique short-range ordered and long-range disordered atomic arrangement. They are important catalytic materials due to their unique chemical and structural properties including broadly adjustable composition, structural homogeneity, and high concentration of coordinatively unsaturated sites. As chemically reduced metal-metalloid amorphous alloys exhibit excellent catalytic performance in applications such as efficient chemical production, energy conversion, and environmental remediation, there is an intense surge in interest in using them as catalytic materials. This critical review summarizes the progress in the study of the metal-metalloid amorphous alloy catalysts, mainly in recent decades, with special focus on their synthetic strategies and catalytic applications in petrochemical, fine chemical, energy, and environmental relevant reactions. The review is intended to be a valuable resource to researchers interested in these exciting catalytic materials. We concluded the review with some perspectives on the challenges and opportunities about the future developments of metal-metalloid amorphous alloy catalysts.

e-Iron carbide has been predicted to be promising for low-temperature Fischer-Tropsch synthesis (LTFTS) targeting liquid fuel production. However, directional carbidation of metallic iron to e-iron carbide is challenging due to kinetic hindrance. Here we show how rapidly quenched skeletal iron featuring nanocrystalline dimensions, low coordination number and an expanded lattice may solve this problem. We find that the carbidation of rapidly quenched skeletal iron occurs readily in situ during LTFTS at 423-473 K, giving an e-iron carbidedominant catalyst that exhibits superior activity to literature iron and cobalt catalysts, and comparable to more expensive noble ruthenium catalyst, coupled with high selectivity to liquid fuels and robustness without the aid of electronic or structural promoters. This finding may permit the development of an advanced energy-efficient and clean fuel-oriented FTS process on the basis of a cost-effective iron catalyst.

Fischer–Tropsch synthesis to lower olefins (FTO) opens up a compact and economical way to the production of lower olefin directly from syngas (CO and H2) derived from natural gas, coal, or renewable biomass. The present work is dedicated to a systematic study on the effect of K in the reduced graphene oxide (rGO) supported iron catalysts on the catalytic performance in FTO. It is revealed that the activity, expressed as moles of CO converted to hydrocarbons per gram Fe per second (iron time yield to hydrocarbons, termed as FTY), increased first with the content of K, passed through a maximum at 646 μmolCO gFe –1 s–1 over the FeK1/rGO catalyst, and then decreased at higher K contents. Unlike the evolution of the activity, the selectivity to lower olefins increased steadily with K, giving the highest selectivity to lower olefins of 68% and an olefin/paraffin (O/P) ratio of 11 in the C2–C4 hydrocarbons over the FeK2/rGO catalyst. The volcanic evolution of the activity is attributed to the interplay among the positive effect of K on the formation of Hägg carbide, the active phase for FTO, and the negative roles of K in increasing the size of Hägg carbide at high content and blocking the active phase by K-induced carbon deposition. The monotonic increase in the selectivity to lower olefins is ascribed to the improved chain-growth ability and surface CO/H2 ratio in the presence of K, which favorably suppressed the unwanted CH4 production and secondary hydrogenation of lower olefins.