Hydrothermal liquefaction (HTL) is a promising process for the energetic valorization of low-value feedstocks. However, HTL crude oils are incompatible with the existing fuel standards, making their upgrade imperative. Nonetheless, the hydrotreatment (HDT) of HTL crude oils is still a challenge due to the complex nature of the feedstock. Therefore, this work explores the relationship between the HTL crude oil origin and the HDT conversion. Five HTL crude oils from different feedstocks, namely, oak sawdust, Brewer’s Spent Grain (spent grain), sewage sludge from two origins, and lignite, and their detailed characterization by elemental analysis, 13C and 31P NMR, molecular weight distribution, comprehensive 2D gas chromatography, and SimDis were compared to those of the HDT liquid product. Lignite displayed the highest potential for producing hydrocarbons, particularly monoaromatics and naphthenes, among the feedstocks tested. The capacity of lignite HTL crude oil to be transformed into hydrocarbons was associated with the absence of compounds resistant to HDT in this feedstock. Similarly, oak sawdust also displayed higher selectivity toward aromatic and naphthene hydrocarbons due to the significant concentration of aromatic compounds in the crude oil. In opposition, the sewage sludge and spent-grain crude oils were particularly selective toward aliphatic hydrocarbons, particularly paraffins, produced from aliphatic components, such as amides, in the crude oil. However, these feedstocks were rich in nitrogenated aromatics, for example, carbazole, which are recalcitrant to hydrotreatment and were not fully converted during the reaction. The differences observed in the HDT liquid composition show that the HTL crude oil composition dictates the potential for producing hydrocarbon fuels. Indeed, HTL crude oils rich in aromatic compounds will yield preferentially naphthenes and aromatic hydrocarbons. In opposition, crude oils richer in aliphatic carbon will be more selective toward paraffins. The nature and concentration of heteroatom components must also be considered since these must be imperatively eliminated.

Global energy demand and environmental concerns about limiting CO 2 emissions have been growing recently. This is why fuel production from renewable resources has become a priority. In this context, microalgae represent an attractive alternative carbon source. In this work, different supported catalysts, including metal phosphide, nitride, and sulfide, were tested for the hydroconversion of bio-oil issued from the hydrothermal liquefaction of microalgae. Supported Ni phosphide catalysts promoted the decarboxylation and decar-bonylation route, while NiMo nitride promoted the hydrodeoxygenation pathway. NiW sulfide catalysts were the most performant, producing a hydrotreated oil with the best higher heating value (HHV), lower aromaticity degree, and lower average molar mass. Among sulfide catalysts, NiWS/SiO 2 À Al 2 O 3 was the least active, probably due to the inhibition of acid sites by the nitrogen compounds. However, NiWS/Al 2 O 3 performed better, showing high hydrogenation performances, which contributed to the conversion of refractory compounds.

Synthesis of high quality colloidal Cerium(III) doped yttrium aluminum garnet (Y3Al5O12:Ce3+, “YAG:Ce”) nanoparticles (NPs) meeting simultaneously both ultra‐small size and high photoluminescence (PL) performance is challenging, as generally a particle size/PL trade‐off has been observed for this type of nanomaterials. The glycothermal route is capable to yield ultra‐fine crystalline colloidal YAG:Ce nanoparticles with a particle size as small as 10 nm but with quantum yield (QY) no more than 20%. In this paper, the first ultra‐small YPO4‐YAG:Ce nanocomposite phosphor particles having an exceptional QY‐to‐size performance with an QY up to 53% while maintaining the particle size ≈10 nm is reported. The NPs are produced via a phosphoric acid‐ and extra yttrium acetate‐assisted glycothermal synthesis route. Localization of phosphate and extra yttrium entities with respect to cerium centers in the YAG host has been determined by fine structural analysis techniques such as X‐ray diffration (XRD), solid state nuclear magnetic resonance (NMR), and high resolution scanning transmission electron microscopy (HR‐STEM), and shows distinct YPO4 and YAG phases. Finally, a correlation between the additive‐induced physico‐chemical environment change around cerium centers and the increasing PL performance has been suggested based on electron paramagnetic resonance (EPR), X‐ray photoelectron spectrometry (XPS) data, and crystallographic simulation studies.