Comparative Evaluation of Thermochemical Liquefaction and Pyrolysis for Bio-Oil Production from Microalgae

Bio-oil is the liquid product of thermochemical liquefaction or pyrolysis of biomass. Thermochemical liquefaction (TCL) is a low temperature (250–350 °C) and high pressure (5–20 MPa) process particularly suited for high moisture feedstocks, whereas pyrolysis is accomplished at moderate to high temperatures (400–600 °C) and atmospheric pressure and requires drying of the feedstock. In this paper, we present experimental results that provide a critical comparison of TCL and slow pyrolysis processes for producing bio-oil from algae. TCL experiments were performed in a 1.8-L Parr reactor using algae slurry (80% moisture) and pyrolysis runs were carried out in an 8-L mild steel cubical reactor, using dried algal powder as received (∼4% moisture). Yields and composition of bio-oil, char, gases, and aqueous phase were evaluated and compared for TCL and pyrolysis. TCL resulted in higher bio-oil yields (∼41%), lower char yields (∼6.3%), and lower energy consumption ratio compared to pyrolysis, which resulted in 23–29% bio-oil, and 28–40% solids yields. Bio-oil obtained from TCL was found to have higher energy density and superior fuel properties such as thermal and storage stabilities, compared to pyrolysis bio-oil

Characterization of Pine Pellet and Peanut Hull Pyrolysis Bio-oils by Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Pyrolysis of solid biomass, in this case pine pellets and peanut hulls, generates a hydrocarbon-rich liquid product (bio-oil) consisting of oily and aqueous phases. Here, each phase is characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to yield unique elemental compositions for thousands of compounds. Bio-oils are dominated by O_<i>x</i> species: few oxygens per molecule for the oily phase and many more oxygens per molecules for the aqueous phase. Thus, the increased oxygen content per molecule accounts for its water solubility. Peanut hull bio-oil is much more compositionally complex and contains more nitrogen-containing compounds than pine pellet bio-oil. Bulk C, H, N, O, and S measurements confirm the increased levels of nitrogen-containing species identified in the peanut hull pyrolysis oil by FT-ICR MS. The ability of FT-ICR MS to identify and assign unique elemental compositions to compositionally complex bio-oils based on ultrahigh mass resolution and mass accuracy is demonstrated

Characterization of Pine Pellet and Peanut Hull Pyrolysis Bio-oils by Negative-Ion Electrospray Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Pyrolysis of solid biomass, in this case pine pellets and peanut hulls, generates a hydrocarbon-rich liquid product (bio-oil) consisting of oily and aqueous phases. Here, each phase is characterized by negative-ion electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI FT-ICR MS) to yield unique elemental compositions for thousands of compounds. Bio-oils are dominated by O_<i>x</i> species: few oxygens per molecule for the oily phase and many more oxygens per molecules for the aqueous phase. Thus, the increased oxygen content per molecule accounts for its water solubility. Peanut hull bio-oil is much more compositionally complex and contains more nitrogen-containing compounds than pine pellet bio-oil. Bulk C, H, N, O, and S measurements confirm the increased levels of nitrogen-containing species identified in the peanut hull pyrolysis oil by FT-ICR MS. The ability of FT-ICR MS to identify and assign unique elemental compositions to compositionally complex bio-oils based on ultrahigh mass resolution and mass accuracy is demonstrated