Thermochemical production of ammonia a two-step metal nitride cycle - materials screening and the strontium-based system.

Ammonia synthesis the catalytic Haber-Bosch process is characterized by its high pressures and low single-pass conversions, as well as by the energy-intensive production of the precursors H and N and their concomitant greenhouse gas emissions. Alternatively, thermochemical cycles based on metal nitrides stand as a promising pathway to green ammonia production because they can be conducted at moderate pressures without added catalysts and be further driven by concentrated solar energy as the source of high-temperature process heat. The ideal two-step cycle consists of the nitridation of a metal to form a metal nitride, followed by the hydrogenation of the metal nitride to synthetize NH and reform the metal.

Alternative ball-milling synthesis of vanadium-substituted polyoxometalates as catalysts for the aerobic cleavage of C-C and C-O bonds.

Vanadium-substituted phosphomolybdic acids (H[PMoVO], denoted as V) are well-known oxidation catalysts that are generally prepared by the hydrothermal treatment of MoO and VO in the presence of HPO. This synthesis procedure is highly energy consuming and the V yields are not always acceptable. In the present work, an alternative hybrid mechanochemical/hydrothermal synthesis of V is proposed, comprising the ball-milling of MoO and VO, followed by a hydrothermal attack.

Physical and chemical characterization of shock-induced cavitation.

A strong impact on a water surface induces a shock wave propagation with a significant pressure variation leading to cavitation bubble formation. A new shock induced cavitation reactor described in this work was characterized by physical and chemical techniques. Water hammer model verification with Joukowsky approach allowed to determine the wave speed propagation and gas fraction in water submitted to shock.

New Approach for Understanding the Oxidation Stability of Neopolyol Ester Lubricants Using a Small-Scale Oxidation Test Method.

This work presents, for the first time, the evaluation on the oxidation stability of synthetic oils for an aircraft engine using the rapid small-scale oxidation test (RSSOT) method. Polyol ester lubricants with and without additives were oxidized at 423 K and 7 bar. The pressure drop plots show that during the first period of thermal degradation, the consumption of oxygen is similar for both samples.

Fast and reversible direct CO2 capture from air onto all-polymer nanofibrillated cellulose-polyethylenimine foams.

Fully polymeric and biobased CO2 sorbents composed of oxidized nanofibrillated cellulose (NFC) and a high molar mass polyethylenimine (PEI) have been prepared via a freeze-drying process. This resulted in NFC/PEI foams displaying a sheet structure with porosity above 97% and specific surface area in the range 2.7-8.