ElsevierTheodet, M.; Quilfen, C.; Martínez, C.; Aymonier, C. (2016). Continuous supercritical synthesis of unsupported and high specific surface area catalyst precursors for deephydrodesulfurization.Abstract: Unsupported and high specific surface area (SBET) catalyst precursors for deephydrodesulfurization (deep-HDS) are obtained using an environmental friendly, continuous and fast synthesis process in supercritical water/alcohol mixtures. This approach offers an access to high production rate and upscaling. Two mixed oxides were synthesized: NiMoO4, which is the preferred material when deep-HDS is investigating, and CoMoO4 preferred for simple HDS. The role of the water/alcohol mixture on the resulting specific surface area has been studied and allows a controlled adjustment of the resulting specific surface area. The obtained NiMoO4 material consists of the highly active hydrate NiMoO4.0.75H2O phase with a controlled composition and specific surface area up to 200 m².g -1 . Resulting materials have shown great performances when tested in deep-HDS catalytic tests.

This article is rather a broad review that presents the main results of studies on mineral syntheses incorporating Ni and Co cations, the interest of developing materials of this type, and some applications where these mineral materials are used as mineral filler. A reflection is then conducted to show that the mineral synthesis rich in Ni and Co makes minerals appear very similar to those found in Ni-and Co-rich lateritic environment. The studies of these lateritic natural environments can provide information on the formation processes of synthetic minerals, and conversely. These two thematic fields will be able to cross-check their data and allow to solve, for example, the chemical fractionation problems encountered in these lateritic environments.

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Many studies in literature have reported supported metal phosphides as promising hydrotreating catalysts. The synthesis of highly dispersed metal phosphide nanoparticles is usually achieved tuning various parameters such as the nature of the phosphorous precursor or the reduction protocol. In this study, the alumina supported molybdenum phosphides were prepared following a newly developed method using supercritical fluids (SCFs) technology including several elementary steps: incipient wetness impregnation and ageing, supercritical CO2 flash‐drying, followed by hydrogen reduction. Experimental parameters allowed us modulating main characteristics of catalysts: crystallinity, reducibility, nanoparticles (NPs) mean size and size distribution. High temperature treatments (400 °C) in scCO2 media lead to the presence of heteropolyanions unlike what is observed in conventional treatment under air. Catalytic performances in selective hydrodesulfurization of methyl‐3‐thiophene, in presence of 2,3‐dimethylbut‐2‐ene, have been assessed and were improved in terms of activity or selectivity compared to MoP and CoMoS reference catalysts, respectively.