Evaluation of Analysis Methods for Formaldehyde, Acetaldehyde, and Furfural from Fast Pyrolysis Bio-oil.

Taina Ohra-Aho,Anja Oasmaa,Atte Mikkelson,Léon Rohrbach,Evert J Leijenhorst,Jozef G M Winkelman,Hero J Heeres,Hans Heeres,Bert Van De Beld

doi:10.1021/acs.energyfuels.1c02208

Abstract

Fast pyrolysis bio-oil (FPBO), a second-generation liquid bioenergy carrier, is currently entering the market. FPBO is produced from biomass through the fast pyrolysis process and contains a large number of constituents, of which a significant part is still unknown. Various analytical methods have been systematically developed and validated for FPBO in the past; however, reliable methods for characterization of acetaldehyde, formaldehyde, and furfural are still lacking. In this work, different analysis methods with (HS-GC/ECD, HPLC, UV/Vis) and without derivatization (GC/MSD, HPLC) for the characterization of these components were evaluated. Five FPBO samples were used, covering a range of biomass materials (pine wood, miscanthus, and bark), storage conditions (freezer and room temperature), and after treatments (none, filtration, and vacuum evaporation). There was no difference among the methods for the acetaldehyde analysis. A significant difference among the methods for the determination of formaldehyde and furfural was observed. Thus, more data on the accuracy of the methods are required. The precision of all methods was below 10% with the exception of the HPLC analysis of acetaldehyde with an RSD of 14%. The concentration of acetaldehyde in the FPBO produced from the three different biomasses and stored in a freezer after production ranged from 0.24 to 0.60 wt %. Storage at room temperature and vacuum evaporation both decreased significantly the acetaldehyde concentration. Furfural concentrations ranged from 0.11 to 0.36 wt % for the five samples. Storage and after treatment affected the furfural concentration but to a lesser extent than for acetaldehyde. Storage at room temperature decreased formaldehyde similarly to acetaldehyde; however, after vacuum-evaporation the concentration of formaldehyde did not change. Thus, the analysis results indicated that in FPBO the equilibrium of formaldehyde and methylene glycol is almost completely on the methylene glycol side, as in aqueous solutions. All three methods employed here actually measure the sum of free formaldehyde and methylene glycol (FAMG).

Highlights

Fast pyrolysis is at its early stage of commercialization with demonstration plants in Finland, The Netherlands, the United States, and Canada and new plants under construction or design in Canada, Finland, and Sweden
This paper focuses on presenting different methods for characterization of formaldehyde, acetaldehyde, and furfural compounds
Acetaldehyde was measured by HS-GC/ECD and HPLC, applying PFBHA and DNPH derivatization as well direct analysis by gas chromatography and a mass selective detector (GC/MSD) of the water extract

Summary

Introduction

Fast pyrolysis is at its early stage of commercialization with demonstration plants in Finland, The Netherlands, the United States, and Canada and new plants under construction or design in Canada, Finland, and Sweden Based on these plants the total fast pyrolysis bio-oil (FPBO) production capacity has been estimated to exceed 180 000 tonnes in 2021. ASTM and EN standards exist for FPBO use in industrial boilers, and a technical report has been prepared for IC-engine use. Reliable methods for characterization of polar components including formaldehyde, acetaldehyde, and furfural from FPBO are still lacking Monitoring of these compounds is important, due to the potential health effect to human

Methods

Results

Conclusion