Structure sensitivity of Cu nanoparticles supported on manganese oxide in hydrogenation of levulinic acid Nayan Jyoti Mazumdar 1 , Praveen Kumar 1 , Miryam Arechavala 1 , Nancy Artioli 2 Haresh Manyar 1 1 Queen's University Belfast, UK, 2 University of Brescia, Italy Levulinic acid (LA) has been recognized by the US Department of Energy as one of the top twelve chemicals, which can be derived from biomass. 1 The selective hydrogenation of LA using metal-based catalysts to γ-valerolactone (GVL), which has applications across food industry as chemical,additives,biofuels due to high energy density.
Scheme 1. Reaction Pathway of LA to GVL In addition, particle size of metal-supported catalysts also affect rate, product distribution. Catalysts between 2–20nm have instigated different activity regimes. 2 This remarkable dependency between particle size–catalyst activity using cheap catalysts (Cu-based) under mild conditions needs to be further explored. Herein, Cu on manganese oxide octahedral molecular sieves (OMS-2) catalysts were prepared by wet-impregnation(Wet-Imp) and precipitation-deposition(Pre-Dep), and their morphology, catalytic activity was compared. LA hydrogenation displayed structure sensitivity which was shown by changes in product yield, turnover frequencies (TOFs) with different Cu-size. This work illustrates that structure-sensitivity of LA hydrogenation to GVL with different sized catalysts prepared by different preparation methods. Materials and Methods: For the synthesis of 5-20wt.% Cu/OMS-2 using Wet-Imp method,Cu(NO 3 ) 2 2.5H 2 O was dissolved in water and OMS-2 was added and heated to 70°C to slowly remove the water, followed by drying and calcination at 550°C. Similarly, Cu (5-20 wt.%) catalysts on OMS-2 were prepared using Pre-Dep method, where ammonium bicarbonate(1M) was slowly added until the pH reached 9 followed by drying and calcination at 450°C. Catalyst activity: All experiments were carried out in 100mL Autoclave Engineers’ reactor. For the reaction, 1g LA along with 1,4-dioxane:H2 O solvent mixture were added, and the reactor was filled up with 1-2 MPa of H 2 . The samples were analyzed using Perkin Elmer Clarus 500 GC equipped with ZB-Wax column and FID detector. Tetrahydrofuran was used as internal standard. Results and Discussion: A series of catalysts with differing wt.% Cu on OMS-2 were prepared by two different methods: Wet-Imp and Pre-Dep, characterised and catalytic activity in liquid phase hydrogenation of LA to GVL was assessed. Different sized Cu nanoparticles (NPs) were prepared with the two methods of preparation. The smaller NPs of Cu as catalysts showed higher LA conversion and GVL yield under same reaction conditions. The catalysts were thoroughly characterised using different characterisation techniques.
USC03
© The Author(s), 2023
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