Characterization and Comparison of Fast Pyrolysis Bio-oils from Pinewood, Rapeseed Cake, and Wheat Straw Using 13C NMR and Comprehensive GC × GC.

Leila Negahdar,Hilal E Toraman,Bert M Weckhuysen,Guy B Marin,Kevin M Van Geem,Joris W Thybaut,Johann T B H Jastrzebski,Arturo Gonzalez-Quiroga,Li Liu,Daria Otyuskaya

doi:10.1021/acssuschemeng.6b01329

Leila Negahdar, Hilal E Toraman + Show 8 more

Open Access

https://doi.org/10.1021/acssuschemeng.6b01329

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Abstract

Fast pyrolysis bio-oils are feasible energy carriers and a potential source of chemicals. Detailed characterization of bio-oils is essential to further develop its potential use. In this study, quantitative 13C nuclear magnetic resonance (13C NMR) combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake. The combination of both techniques provided new information on the chemical composition of bio-oils for further upgrading. 13C NMR analysis indicated that pinewood-based bio-oil contained mostly methoxy/hydroxyl (≈30%) and carbohydrate (≈27%) carbons; wheat straw bio-oil showed to have high amount of alkyl (≈35%) and aromatic (≈30%) carbons, while rapeseed cake-based bio-oil had great portions of alkyl carbons (≈82%). More than 200 compounds were identified and quantified using GC × GC coupled to a flame ionization detector (FID) and a time of flight mass spectrometer (TOF-MS). Nonaromatics were the most abundant and comprised about 50% of the total mass of compounds identified and quantified via GC × GC. In addition, this analytical approach allowed the quantification of high value-added phenolic compounds, as well as of low molecular weight carboxylic acids and aldehydes, which exacerbate the unstable and corrosive character of the bio-oil.

Highlights

Lignocellulosic biomass has emerged as a potential alternative source of specialty chemicals, gaseous and liquid fuels, and thermal energy
Combined with comprehensive two-dimensional gas chromatography (GC × GC) was used to characterize fast pyrolysis bio-oils originated from pinewood, wheat straw, and rapeseed cake
We present a detailed characterization study of these three distinct bio-oils using a combination of quantitative 13C nuclear magnetic resonance (13C nuclear magnetic resonance (NMR)) and GC × GC-flame ionization detector (FID)/time of flight mass spectrometer (TOF-MS). 13C NMR spectroscopy is used to characterize the major functional groups

Summary

Introduction

Lignocellulosic biomass has emerged as a potential alternative source of specialty chemicals, gaseous and liquid fuels, and thermal energy. The transformation of lignocellulosic biomass into liquid bio-oil through the fast pyrolysis process is receiving increased attention.[1−4] Fast pyrolysis bio-oil exhibits key advantages: it is produced at high yields (up to 70 wt %), suitable for decentralized production, and practical for handling, transport, and storage and has a much higher energy density as compared to the parent biomass.[5,6]. Fast pyrolysis bio-oils are complex mixtures of water and oxygenated compounds, including carbohydrates, heterocyclics, phenolics, carboxylic acids, aldehydes, ketones, esters, and alcohols.[7,8] To fully realize the potential of the fast pyrolysis process, detailed knowledge on the chemical composition of the bio-oil is essential.[7,9,10].

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