Biomass, as a renewable material for energy which has a
negligible content of sulfur and nitrogen, is supposed to be very
clean. The fast pyrolysis of biomass has aroused great attention
in recent decades. However, bio-oil has some disadvantages
such as high viscosity, thermal instability, corrosiveness and chemical
complexity, which set up many obstacles before its full utilization
as a kind of renewable energy. Among the upgraded
methods, the hydrotreatment of bio-oil as one of potential
methods has been widely studied and it is shown that the caloric
value and storage stability increased dramatically. But the process
conditions are rather severe (350–450 C, 5–15 MPa), leading to
the formation of substantial amounts of gases and undesirable
char. Thus there is a strong incentive to develop new ways to operate
the process at lower temperature and hydrogen pressure.