Mn-promoted hydrogenation of microalgae (Chlorococcum sp.) to 1,2-propanediol and ethylene glycol over Ni-ZnO catalysts

Abstract

Mn-promoted nickel-based catalysts were explored for the direct hydrogenation of microalgae (Chlorococcum sp.) containing 49.6% of carbohydrates in water. With this catalyst at 250 °C for 3.0 h, microalgae was completely decomposed, where the conversion of microalgae to liquid products (CTL) and the total yield of polyols reached 66.9%, and 53.6%, respectively. Among polyols, the total yield of 1,2-propanediol and ethylene glycol were 41.7%. XRD, XPS and TEM-EDX characterizations showed that 5% of Mn addition, 350 °C of reduction temperature and the co-precipitation synthesis ensured the excellent dispersion of the Ni catalyst with small particle sizes. The Mn promoter was found to stabilize the catalyst structure by preventing the Ni particles from aggregation and to effectively promote retro-aldol and dehydroxylation reaction due to the increasing number of Lewis acid sites. Meanwhile, the hydrogenation pathways over nickel-based catalysts were proposed.