Catalyst structure-based hydroxymethylfurfural (HMF) hydrogenation mechanisms, activity and selectivity over Ni

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2021-05, Vol.412, p.127553, Article 127553
• Main Authors: Pomeroy, Brett, Grilc, Miha, Gyergyek, Sašo, Likozar, Blaž
• Format: Article
• Language: English
• Subjects: Bio-based chemicals; Catalytic hydrodeoxygenation; Hydrogenation and dehydroxylation; Hydroxymethylfurfural; Reaction kinetics
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2020.127553

[Display omitted] •Experimental and in-silico study on HDO of biobased 5-hydroxymethylfurfural.•Deoxygenation at higher temperatures relative to reduction of the aldehyde.•Despite reducibility improvements, La promotion slowed reaction rates and activity.•Nb promotion facilitated deoxygenation rates and humin formation.•Directly comparable kinetic parameters and TOF for carbon-supported Ni catalysts. Catalytic hydrodeoxygenation of hydroxymethylfurfural was investigated in a three-phase batch reactor over a range of reaction temperatures (170–230 °C), under 5 MPa of hydrogen, and tetrahydrofuran solvent. Nickel-based carbon-supported catalysts were also promoted by lanthanum and niobium, despite promoters alone demonstrated no activity. Based on experimentally-obtained liquid products, a reaction pathway was proposed and a microkinetic model was established, by considering adsorption, desorption and surface reaction kinetics, mass transfer and thermodynamics. An unpromoted Ni/C resulted in primarily unsaturated furan diol, a highly desirable intermediate in the polymer industry. As reaction temperatures increased > 200 °C, dehydration yielded deoxygenated products suitable for solvents and biofuel. In spite of enhancements to reducibility, La-promotion significantly decreased both hydrogenation (8-times) and deoxygenation (25-times) rate constants. Alternatively, Nb-incorporation offered additional acidity, while lower activation energies resulted in 200% higher deoxygenation rates via dehydration reactions and humin formation at lower temperatures. It exhibited the highest deoxygenation activity.