Highly dispersed copper oxide on silica: Towards an efficient catalyst for continuous glycerol dehydration to acetol
Jaime Mazarío, Juan Antonio Cecilia, Enrique Rodrı́guez-Castellón, Marcelo E. Domine
Abstract
In most current processes aimed at producing biodiesel glycerol is still a co-product, and its valorisation is essential for the biorefinery. This work relies on previous results showing the dependence of the selective dehydration of glycerol to acetol (hydroxyacetone) on achieving a moderate acidity and the redox functionality of copper to complete the chemical process. In this sense, this reaction was studied using CuO supported on silica. Different silicas and copper incorporation methodologies were investigated to develop the best CuO/SiO 2 material. Interestingly, these CuO-based materials developed acidity and became more active when increasing the copper oxide dispersion, thereby going from poorly to intensely effective to dehydrate glycerol selectively to acetol. Catalysts were characterised by different techniques (i.e., ICP, N 2 adsorption, XRD, TPR, HR-TEM, etc.) to explain the differences observed in catalytic activity and acetol yield based on their physicochemical properties. Highly dispersed CuO small nanoparticles (≤ 3 nm) on SiO 2 leading to Cu-O-Si-O sites (precursors of Cu(I) more active species) with adequate acidity and reducibility are capable to catalyse the selective dehydration of glycerol to acetol. • Adequately optimised CuO/SiO 2 selectively catalyses continuous glycerol dehydration to acetol. • CuO dispersion on silica clearly affects catalyst acidity, reducibility, and Cu-O-Si-O sites. • Average CuO particle sizes equal to or below 3 nm (by N 2 O) on SiO 2 achieve near 60% acetol yields. • Catalyst deactivation by copper sintering remains a challenge.