Franck Rataboul

Synthesis and characterization of monodisperse zinc and zinc oxide nanoparticles from the organometallic precursor [Zn(C6H11)2]

Abstract Decomposition of the organometallic precursor [Zn(C6H11)2] in wet anisole leads to the formation of monodisperse spherical Zn particles of 6 nm mean diameter. High resolution electron microscopy (HRTEM) indicates the crystalline nature of these particles and photoelectron studies (XPS) are consistent with the presence of both zinc and zinc oxide. In the presence of polyvinylpyrolidone (PVP), the decomposition leads to well dispersed nanoparticles for which HRTEM studies evidenced the presence of hexagonal zinc (0) surrounded by a thin layer of hexagonal zinc oxide of wurtzite type. The thermal oxidation of these zinc nanoparticles yields well-crystallized nanoparticles of ZnO without coalescence or size change. An X-ray diffraction pattern shows that the powder consists of pure hexagonal wurtzite-type phase.

Direct Solid Lewis Acid Catalyzed Wood Liquefaction into Lactic Acid: Kinetic Evidences that Wood Pretreatment Might Not be a Prerequisite

The objective of the present work was to determine if wood sawdust can be used instead of isolated cellulose in the general solid‐acid‐catalyzed production of chemicals. The kinetics of model cellulose and pine‐wood sawdust liquefaction into lactic acid were determined in the presence of a solid Lewis acid, ZrW. The catalytic hydrolysis of pine wood was performed at 190u2009°C in a large‐scale batch reactor (2.5u2005L). Similar kinetic curves of lactic formation were obtained for cellulose and wood as substrates. Moreover, the initial lactic acid production rate of pine‐wood sawdust was higher than that of model cellulose, proving that, in spite of the presence of lignin/hemicellulose, the catalyst drives the transformation towards lactic acid formation. However, our results give also evidence of solid‐catalyst deactivation for both cellulose and wood substrates. This result indicates that if wood pretreatment can be bypassed, the bottleneck will be the solid‐catalyst regeneration and recycling.