Obtaining
a tar-free biosyngas from biomass gasification processes
has been the subject of many studies in the past 2 decades, and it
still remains the major technologic and economic challenge. Unfortunately,
the countless publications about gasification technologies and different
techniques permitting reduction of the tar present at the outlet of
gasifier reactors usually confuse inexperienced persons who attempt
to further research this subject. More than presenting the basis of
biomass gasification technologies and positioning them among other
bioenergies, this work mainly aims at reviewing and comparing the
different methods developed in order to produce a tar-free biosyngas.
In this way, biosyngas quality improvement can be obtained through
different operating processes such as reactor designs, gasifying ratios,
feedstock, temperature, and space ratio. Since catalytic destruction
has proved to be one of the most convenient and efficient ways to
eliminate undesirable tars, an important part of this work also highlights
the catalytic and deactivating phenomena involved. Furthermore, this
work takes inventory of numerous studies conducted to understand the
influence of different properties, especially supports and active
site compositions, on the tar reforming activities and lifetime of
catalyst materials. Thus, this review aims at summarizing basic and
more recent improvements applied to biomass gasification processes
and catalytic syngas purification.