t-BuOK catalyzed bio-oil production from woody biomass under sub-critical water conditions

Environ Chem Lett (2013) 11:2531 DOI 10.1007/s10311-012-0373-3

ORIGINAL PAPER

t-BuOK catalyzed bio-oil production from woody biomass

under sub-critical water conditions

Kubilay Tekin Selhan Karagz

Received: 21 November 2011 / Accepted: 25 June 2012 / Published online: 12 July 2012 Springer-Verlag 2012

Abstract The substitution of fossil fuels and fossil-based products with biofuels and biomass-based products is indispensable for a sustainable society and a green environment. The liquefaction of biomass to produce biofuels under sub- and/or super-critical water conditions is one of the most promising methods that might allow this substitution. Here, for the rst time, we report the results of the liquefaction of woody biomass under sub-critical water conditions at 250, 300, and 350 C using potassium tertbutoxide (t-BuOK) as a catalyst. To compare and evaluate the catalytic performance of t-BuOK, the experiments were also performed under identical conditions using KOH as the catalyst. The product distributions obtained using either KOH or t-BuOK as the catalyst were very similar. The total oil yields increased and the solid residue yields decreased when either KOH or t-BuOK were used at reaction temperatures of 300 and 350 C. The total bio-oil yields obtained at 300 C with t-BuOK and KOH were41.9 weight (%) and 43.0 weight (%), respectively, whereas the total bio-oil yield from the thermal run at 300 C was approximately 24.0 weight (%). Although the

O/C ratio of the raw material is 0.70, the O/C ratios of the light and heavy bio-oils obtained from the KOH catalytic run are 0.38 and 0.25, respectively. In addition, the O/C ratios for the light and heavy oils obtained from the t-BuOK catalyst are 0.41 and 0.26, respectively. We estimate that the heating values of the light and heavy bio-oils obtained by either catalytic run (t-BuOK or KOH) are approximately 24 MJ kg-1 and 29 MJ kg-1, respectively

Keywords Biomass Sub-critical water Light bio-oil

Heavy bio-oil t-BuOK Liquefaction

Introduction

The term biofuels refers to all forms of fuels derived from biomass. Biofuels, unlike petroleum-derived fuels, have a low nitrogen and sulfur content and a high oxygen content. In addition, biofuels, which represent renewable and environmentally friendly fuels, are a good alternative to fossil fuels. The production of biofuels from the thermochemical conversion of biomass can be carried out using two...