Structure‐Reactivity Relations in Ruthenium Catalysed Furfural Hydrogenation

Abstract

Furfural is an abundant and low‐cost bio‐derived platform chemical, obtained by xylose dehydration, and an important precursor to furfuryl alcohol and furan resins. The liquid phase selective hydrogenation of furfural to furfuryl alcohol was systematically investigated over silica supported Ru nanoparticles to elucidate structure‐reactivity relations and obtain mechanistic insight. Furfural hydrogenation to furfuryl alcohol is weakly structure sensitive for Ru nanoparticles spanning 2 to 25 nm, and the dominant reaction pathway reaching 95 % selectivity under our conditions (<25 bar H2 and 100–165 °C). In contrast, furfural decarbonylation to furan exhibits a strong structure sensitivity, being favoured over sub‐10 nm particles. Increasing pH2 from 10 to 25 bar resulted in a modest increase in C=O hydrogenation, while higher temperatures promoted ring‐opening of furfuryl alcohol.

Influence of Structure Sensitivity on Apparent Activation Energy of Parallel Heterogeneous Catalytic Reactions

“…The expressions for apparent activation energies along two routes as a function of the metal cluster size are rather complex Equations (50)-(52) are rather cumbersome to analyse dependences of activation energy on the cluster size. For a particular case of furfural hydrogenation to furfuryl alcohol and decarbonylation to furan and CO 2 [25] exhibiting the first order dependence in the substrate in both reactions and the first order in hydrogen for the hydrogenation reactions, . Figure 3 illustrates correspondence between the experimental data and calculations for the reaction rates and activation energies for formation of furfuryl alcohol and furan using the data reported in [25].…”

“…The mechanism assumes competitive adsorption of hydrogen and can be used for example for analysis of Ru catalysed furfural transformations resulting in hydrogenation to furfuryl alcohol and decarbonylation to furan and CO 2 [25].…”

“…The experimental data in [25] correspond to the first order dependence in the substrate concentration along both pathways and the first order in hydrogen pressure for hydrogenation. It is, however, instructive to analyze an expression for the apparent activation energy in the case of an Eley-Rideal reaction mechanism, where the apparent turnover frequency is defined through respective contributions on terraces and edges An expression for the apparent activation energy can be derived using the same approach as discussed above giving (60) k app,TOF e −E a,TOF ∕RT = k t e −E a,t ∕RT K t e −ΔH a,t ∕RT C A 1 + K t e −ΔH a,t ∕RT C A f terraces + k e e −E a,e ∕RT K e e −ΔH a,e ∕RT C A 1 + K e e −ΔH a,e ∕RT C A (1 − f terraces )…”

An Account of the Catalytic Transfer Hydrogenation and Hydrogenolysis of Carbohydrate‐Derived Renewable Platform Chemicals over Non‐Precious Heterogeneous Metal Catalysts

“…and earth‐abundant non‐precious metals (Ni, Cu, Co, Fe, Zn, etc.) have been employed to overcome these hurdles [15,19] . Theoretical studies reveal that FUR absorbs on group VIII metals (Pt, Pd, and Ni) via flat η 2 ‐(C−O) binding mode [11b,20] .…”

Meet the Women of Catalysis

“…Karen's research focuses on the development of tunable porous heterogeneous catalysts for use in green and sustainable chemistry and the utilization of renewable resources in chemical processes. She is particularly interested in understanding structure‐reactivity relations in catalysis, the impact of hierarchically porous catalysts on mass transport in catalytic reactions, and methods to tune surface hydrophobicity or improve the hydrothermally stability of porous catalysts for aqueous phase processes …”