Applied Catalysis B: Environmental 154–155 (2014) 294–300 Contents lists available at ScienceDirect Applied Catalysis B: Environmental j ourna l h omepa ge: www.elsevier.com/locate/apcatb Highly selective rearrangement of furfuryl alcohol to cyclopentanone Milan Hronec ∗ , Katarína Fulajtárova, Tomᡠs Soták Department of Organic Technology, Slovak University of Technology, Radlinského 9, 812 37 Bratislava, Slovakia a r t i c l e i n f o Article history: Received 3 January 2014 Received in revised form 10 February 2014 Accepted 13 February 2014 Available online 22 February 2014 Keywords: Furfuryl alcohol Cyclopentanone Hydrogenation Metal catalysts Aqueous-phase Cyclopentenone a b s t r a c t The aqueous phase hydrogenation of furfuryl alcohol to cyclopentanone was carried out on a series of metal supported and bulk catalysts. The effect of catalyst concentration, temperature, hydrogen pressure and reaction time has also been investigated. By changing the partial hydrogen pressure and concen- tration of metal catalyst it is possible to transform furfuryl alcohol with a very high selectivity either to furfuryl alcohol or cyclopentanone. High hydrogen pressure and catalyst concentration favours the formation of tetrahydrofurfuryl alcohol. At very low concentration of metal catalyst (0.25–1.0 wt%) and 0.8–2.5 MPa of hydrogen pressure, the product is exclusively cyclopentanone formed in yields higher than 95 mol%. Very active and selective are nickel type catalysts. The differences in selectivities of prod- ucts distribution are explained by the proposed reaction mechanism consisting of two parallel reactions. One reaction is catalyzed preferably by hydrogen ions produced by self-dissociation of water and other by metal catalyst. © 2014 Elsevier B.V. All rights reserved. 1. Introduction In the past years the production of chemicals from biomass has received increased attention in view of the replacement of petroleum. Furfural is one of basic chemicals obtained from hemi- cellulose raw material via acid-catalyzed dehydration [1–7]. Gas or liquid-phase hydrogenation of multifunctional furfural (FA) over heterogeneous catalysts can produce various useful products described recently in overviews by Nakagawa et al. [8] and Gallezot [9]. Selective hydrogenation of the C=O bond of furfural leads to an industrially important chemical, furfuryl alcohol (FAL), which is applied mostly in polymer industry for the production of corrosion and acid-resistant materials. Subsequent hydrogenation of the C=C bonds of furfuryl alcohol gives tetrahydrofurfuryl alcohol (THFA), usually used as a green solvent. Nickel based catalysts [10,11] and noble metals [12,13] are generally applied for this reaction in a liq- uid phase. Recently, we have reported [14] that in water as a solvent furfural and furfuryl alcohol in the presence of heterogeneous Pt, Pd, Ru, Ni catalysts are at higher temperatures and hydrogen pressures selectively converted to cyclopentanone. Under these conditions and in the absence of metal catalysts the main products of fur- furyl alcohol conversion in water are 4-hydroxy-2-cyclopentenone (4-HCP) and polymers of furfuryl alcohol [15]. These products are result of acid-catalyzed ring-rearrangement reaction of furfuryl ∗ Corresponding author. Tel.: +421 2 59325328. E-mail address: milan.hronec@stuba.sk (M. Hronec). alcohol and its polymerization. Acid catalyst (H 3 O + ) is formed by self-dissociation of water serving as the solvent. Cyclopentanone is a versatile compound used for the synthe- sis of fungicides, pharmaceuticals, rubber chemicals, and flavour and fragrance chemicals [16]. Potentionally, it can be used for preparation of polyamides [17] and C 15 –C 17 diesel or jet fuels [18]. Cyclopentanone can be prepared by the catalytic vapour-phase cyclisation of 1,6-hexanediol [19] or adipic esters [20–22] or by the liquid phase oxidation of cyclopentene with nitrous oxide [23,24]. In all these processes petroleum-based products are used as feed stocks. In this paper, we report how we can principally change the selectivity of furfuryl alcohol conversion in water either to tetrahy- drofurfuryl alcohol or to cyclopentanone by varying the hydrogen pressure or concentration of metal catalyst. The knowledge of this dependence offers us the possibility to achieve very high yields of cyclopentanone directly from furfuryl alcohol at very low cat- alyst concentrations and hydrogen pressures. To the best of our knowledge, no available literature describes such highly selective conversion of furfuryl alcohol to cyclopentanone under comparable concentration and reaction conditions. 2. Materials and methods 2.1. Materials Furfuryl alcohol (98%), tetrahydrofurfuryl alcohol (99%), cyclopentanone (99%) and cyclopentanol (99%) were purchased from Sigma–Aldrich, and were used without purification. Pt, Pd http://dx.doi.org/10.1016/j.apcatb.2014.02.029 0926-3373/© 2014 Elsevier B.V. All rights reserved.