Pyrolysis is an important
thermochemical route to decompose lignocellulose
biomass into biogas, bio-oil, and biochar, which can be then converted
into value-added biofuels, chemicals, and biomaterials. Conventionally,
the pyrolysis reaction is carried out under inert atmosphere. The
quality of biocrudes and biochars from the conventional pyrolysis
could significantly vary, depending on the types of feedstocks and
reaction conditions. After intensive studies on the conventional biomass
pyrolysis for decades, the external heat supply for the endothermic
pyrolytic reactions is still one of the most important roadblocks
to inhibit the scale-up and commercialization of biomass pyrolysis
technologies. Different from the pyrolysis under inert gas atmosphere,
autothermal pyrolysis tends to depolymerize the biomass (polymers)
with restricted supply of oxygen/air, also called oxidative pyrolysis.
The presence of oxygen in the pyrolyzer will induce the exothermic
char-oxygen and/or volatile-oxygen reactions, thus in situ providing
the heat for the primary thermal degradation of biomass and the subsequent
secondary reactions. Besides the change in product distributions,
the key advantage of autothermal pyrolysis is its self-sustainability
in terms of heat supply and requirement, facilitating the ease of
further scaling up. This review will thus mainly focus on the sum
of the recent advances in autothermal pyrolysis and also discuss some
innovative pathways for improving/adjusting the product quality.