The conversion of wood to produce biofuels by heterogeneous catalysis has received strong attention in recentyears. Of the various thermochemical processes available,pyrolysis is the preferred conversion method.Pyrolysis isan appropriate process for the conversion of large amounts of wood into bio-oil, from which biofuels and chemicals can be produced (Figure 5). However, some important bio-oil characteristics are disadvantageous, such as high water and oxygen content, corrosiveness, lower stability, immiscibility with crude-oil-based fuels, high acidity, high viscosity, and low calorific value. Therefore, improvement of the bio-oil quality
is a prerequisite before upgrading to biofuels can be envisaged.A number of processes have been introduced for the thermochemical conversion of wood-based biomass to biofuels and/or chemicals; however, the quality of the bio-oil produced is too low for processing to valuable products