CAS State Key Laboratory of Advanced Special Steel & Shanghai Key Laboratory of Advances Ferrometallurgy & School of Materials Science and Engineering, Shanghai University, 99 Shangda Road, Shanghai 200444, China.
Phys Chem Chem Phys. 2018 May 9;20(18):12791-12798. doi: 10.1039/c8cp00873f.
Experimental and computational studies were carried out to investigate the oxidation of pentlandite (Fe4.5Ni4.5S8). The oxidation product was first analyzed by energy dispersive spectrometry to reveal the elemental distribution at the cross section. Our experimental study shows that the Fe atoms in pentlandite migrated to the surface and were preferentially oxidized to form a thin layer of Fe2O3, whereas the Ni atoms remained at the center of the grain. Furthermore, density functional theory calculations were performed to investigate the adsorption and diffusion of atomic oxygen as well as the adsorption and dissociation of molecular oxygen on the (001) and (010) surfaces of pentlandite. From the calculated adsorption energies of atomic oxygen at the different sites of the (001) and (010) surfaces, we found that oxidation of the Fe sites was preferable to that of the Ni sites when exposed to an oxidizing atmosphere. For molecular oxygen adsorption on the surfaces of pentlandite, the bridge sites (Fe-Ni and Fe-Fe) were found to be the most favorable adsorption sites. The dissociative adsorption of O2 is thermodynamically more favorable than the molecular adsorption. Calculated dissociation barriers show that the oxidation is feasible during high temperature roasting.
进行了实验和计算研究，以研究镍黄铁矿（Fe4.5Ni4.5S8）的氧化。首先通过能谱分析对氧化产物进行分析，以揭示截面处的元素分布。我们的实验研究表明，镍黄铁矿中的 Fe 原子迁移到表面并优先被氧化形成一层薄的 Fe2O3，而 Ni 原子则留在颗粒中心。此外，还进行了密度泛函理论计算，以研究原子氧在镍黄铁矿（001）和（010）表面上的吸附和扩散，以及分子氧在镍黄铁矿表面上的吸附和离解。从原子氧在（001）和（010）表面不同位置的计算吸附能可以发现，在氧化气氛中，Fe 位的氧化优先于 Ni 位的氧化。对于分子氧在镍黄铁矿表面上的吸附，桥位（Fe-Ni 和 Fe-Fe）被发现是最有利的吸附位。O2 的离解吸附在热力学上比分子吸附更有利。计算的离解势垒表明，在高温焙烧过程中氧化是可行的。
