Defect mediated functionalization of multiwalled carbon nanotubes: a novel route to design basic heterogeneous catalysts for the synthesis of fuels and chemicals from biomass

Introduction Biomass conversion to transportation fuels and chemicals is a growing field of research due to the depletion of fossil fuels feedstock. New catalysts, optimized for carbohydrates conversion, need to be developed. In this context, basic heterogeneous catalysts will play a major role for dehydration, hydrolysis, (trans)esterification, aldol condensation, alkylation or isomerization reactions for example. In contrast to existing basic heterogeneous catalysts, MWCNTs-based catalysts are chemically stable (no leaching) and relatively easy to tailor on a nanoand macro-level (controlled porosity). Therefore, nitrogen-functionalized multiwalled carbon nanotubes (NMWCNTs) appear to be a promising basic catalyst and catalyst support [1]. Unfortunately, the nitrogen concentration, its location in/on the nanotube and the nature of the formed Ncontaining functional groups are difficult to control by common synthesis techniques like by catalytic chemical vapor deposition (CCVD) or by post-treatments [2]. In addition, it is still unclear which functional groups are required to reach high catalytic activities. Thus, we synthesized N-MWCNTs catalysts by grafting desired N-containing molecules on the MWCNTs’ surface. In order to avoid the drawbacks of the traditional SOCl 2 route, a new procedure has been designed. The obtained catalysts have been tested in the transesterification of glyceryl tributyrate, as a model triglyceride for biodiesel synthesis