1 Hydroconversion mechanism of biomass-derived γ-valerolactone Gyula Novodárszki, a Hanna E. Solt, a György Lendvay, a R. Magdolna Mihályi, a Anna Vikár, a Ferenc Lónyi,* a Jenő Hancsók, b and József Valyon a a Institute of Materials and Environmental Chemistry, Research Center for Natural Sciences, Magyar tudósok körútja 2, H-1117 Budapest, Hungary. E-mail: lonyi.ferenc@ttk.mta.hu b Department of MOL Hydrocarbon and Coal Processing, University of Pannonia, Egyetem utca 10, H-8200 Veszprém, Hungary Abstract The hydroconversion mechanism of γ-valerolactone (GVL) was studied over a Co/SiO 2 and a Pt/aluminosilicate catalyst. The reaction was carried out at 250 °C, 30 bar, and WHSV= 1 g GVL ·g cat. -1 ·h -1 . The Co/SiO 2 catalyst had moderate hydrogenation activity and Lewis acidity, whereas the Pt/aluminosilicate catalyst had high hydrogenation activity and Brønsted acidity. Diffuse Reflectance Fourier Transform Spectroscopic (DRIFTS) results suggested that the GVL ring was bounded more strongly to the stronger acid Pt/aluminosilicate that to the weaker acid Co/silica catalyst. The Pt/aluminosilicate catalyst was substantiated to open the GVL ring in a protonation/deprotonation process giving pentenoic acid (PE) intermediate and pentanoic acid (PA) as main final product. Over Co/SiO 2 catalyst 2-methyl-tetrahydrofuran (2-MTHF) and pentanol were the major products of GVL conversion. It was substantiated that latter transformation proceeded in consecutive hydrogenation and dehydration steps via 2- hydroxy-5-methyl-tetrahydrofuran and 1,4-pentanediol (1,4-PD) intermediates. The oxygen atoms of GVL were shown to establish H-bonds with the silanol groups of the Co/SiO 2 catalyst. The  CO frequency of the adsorbed GVL depends on the adsorption interaction of the GVL and the silica surface. Three distinct  CO bands were distinguished by DRIFTS. Quantum chemical calculations gave the structures of the three adsorbed GVL species. Operando DRIFTS examination of the catalytic reaction suggested that in the structure that was activated for hydrogenation/hydrogenolysis both the ring and the carbonyl oxygen were bound to silanol groups. Keywords : gamma-valerolactone (GVL) hydroconversion, GVL bonding to silica, 2-methyltetrahydrofuran, pentanoic acid, DRIFT spectroscopy 1. Introduction Fossil carbon sources are to be increasingly replaced by renewable carbonaceous materials both in energy and chemical industries, in order to decrease emission of greenhouse gas carbon dioxide and, thereby, to mitigate global warming [1-7]. Gamma-valerolactone (GVL) can be easily derived from lignocellulosic waste, which is an abundant renewable carbon source. GVL is relatively inexpensive and has the functionality and reactivity to be used as platform compound for producing a number of value-added chemical products [2,3,5,8-10]. A plausible direction of lactone conversion is its reduction to diol. Organic © 2019. This manuscript version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/ This manuscript has been published in final form at https://linkinghub.elsevier.com/retrieve/pii/S0920586118307648 DOI: 10.1016/j.cattod.2019.02.020