An
international round robin study of the production of fast pyrolysis
bio-oil was undertaken. A total of 15 institutions in six countries
contributed. Three biomass samples were distributed to the laboratories
for processing in fast pyrolysis reactors. Samples of the bio-oil
produced were transported to a central analytical laboratory for analysis.
The round robin was focused on validating the pyrolysis community
understanding of production of fast pyrolysis bio-oil by providing
a common feedstock for bio-oil preparation. The round robin included:
distribution of three feedstock samples, hybrid poplar, wheat straw,
and a blend of lignocellulosic biomasses, from a common source to
each participating laboratory, preparation of fast pyrolysis bio-oil
in each laboratory with the three feedstocks provided, and return
of the three bio-oil products (minimum of 500 mL) with operational
description to a central analytical laboratory for bio-oil property
determination. The analyses of interest were CHN, S, trace element
analysis, water, ash, solids, pyrolytic lignin, density, viscosity,
carboxylic acid number, and accelerated aging of bio-oil. In addition,
an effort was made to compare the bio-oil components to the products
of analytical pyrolysis through gas chromatography/mass spectrometry
(GC/MS) analysis. The results showed that clear differences can occur
in fast pyrolysis bio-oil properties by applying different process
configurations and reactor designs in small scale. The comparison
to the analytical pyrolysis method suggested that pyrolysis (Py)–GC/MS
could serve as a rapid qualitative screening method for bio-oil composition
when produced in small-scale fluid-bed reactors. Gel permeation chromatography
was also applied to determine molecular weight information. Furthermore,
hot vapor filtration generally resulted in the most favorable bio-oil
product, with respect to water, solids, viscosity, and carboxylic
acid number. These results can be helpful in understanding the variation
in bio-oil production methods and their effects on bio-oil product
composition.