Short Communication Bio oil synthesis by coupling biological biomass pretreatment and catalytic hydroliquefaction process S. Hamieh a,b , R. Beauchet a , L. Lemee a , J. Toufaily b , B. Koubaissy b , T. Hamieh b , Y. Pouilloux a , L. Pinard a,⇑ a IC2MP, Institut de Chimie, des Milieux et Matériaux de Poitiers, Univeristy of Poitiers, 4 rue Michel Brunet, 86000 Poitiers, France b MCEMA, Laboratory of Materials, Catalysis, Environment and Analytical Methods, Faculty of Sciences I, Lebanese University, Campus Rafic Hariri, Hadath, Lebanon highlights  Direct liquefaction reaction of waste organic matter using Raney Nickel and tetralin.  Biological pretreatment enhances Humin content and the liquefaction process.  Humin fraction as promoter and Humic acids as refractory to liquefaction reaction.  Bio oil heating value close to biopetroleum. graphical abstract article info Article history: Received 23 October 2013 Received in revised form 15 January 2014 Accepted 18 January 2014 Available online 26 January 2014 Keywords: Liquefaction Humic substances Bio oil Biological pretreatment abstract The bio-oil synthesis from a mixture of wastes (7 wt.% straw, 38 wt.% wood, and 45 wt.% grass) was carried out by direct liquefaction reaction using Raney Nickel as catalyst and tetralin as solvent. The green wastes were biologically degraded during 3 months. Longer the destructuration time; higher the yield into oil is. Biological pretreatment of green wastes promotes the liquefaction process. Among the compo- nents of degraded biomass, Humin, the major fraction (60–80 wt.%) that was favored by the biological treatment, yields to a bio oil extremely energetic with a HHV close to biopetroleum (40 MJ kg 1 ), con- trariwise, Fulvic acids (2–12 wt.%), the minor fraction is refractory to liquefaction reaction. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Waste organic matter, despite of their high oxygen content and low Higher Heating Value (HHV), have the potential to be a valu- able substitute to fuel production through thermochemical conver- sion (Rezzoug and Capart, 2003). Contrariwise to gasification and pyrolysis processes, direct hydroliquefaction does not require dry- ing of the feedstocks, which takes large quantities of energy and time (Minarick et al., 2011). Direct hydroliquefaction consist to add hydrogen to the hydrogen deficient organic structure of the biomass, breaking it down as far as is necessary to produce distil- lable liquids. This process is very versatile, and can be applied to a wide range of biomasses such as municipal wastes, green wastes, primary sludge and microalgae (Lemoine et al., 2013), and many other high-moisture feedstocks (Elliott et al., 1988). It is a chemical reforming process in which the depolymerization, the deoxygen- ation of organic waste materials and the hydrogenation of reaction products occur at the same time (Chornet and Overend, 1985). To get a fuel (bio oil) of high quality, oxygen content must be lower than 6 wt.%, and the hydrogen to carbon ratio (H/C) higher than 1.5 (Wang et al., 2008). Therefore, both oxygen removal (through decarbonylation, decarboxylation and dehydration reactions) and hydrogen transfer are promoted in a heated, hydrogen pressurized enclosure. Hydrogen donor solvents as 1,2,3,4-tetrahydronaphta- lene (tetralin) may be added to increase the hydrogen to carbon ratio and to reduce the oxygen to carbon ratio, thereby improving hydrocarbons yield (Johannes et al., 2012). Moreover, the addition http://dx.doi.org/10.1016/j.biortech.2014.01.070 0960-8524/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +33 (0)5 49 45 39 05; fax: +33 (0)5 49 45 37 74. E-mail address: ludovic.pinard@univ-poitiers.fr (L. Pinard). Bioresource Technology 156 (2014) 389–394 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech