Industrialised countries used hardwood biomass to manufacture several chemi­cals and products since late 1930s. One example is the Ford Plant, in which the hardwood biomass is converted to esters for automotive (Nelson 1930). Plant — based esters can be classified as the green solvents. For an example, glycerol carbonate is used as nonreactive diluents in epoxy or polyurethane systems and 2 ethylhexyl lactate can be used as degreaser and as green solvent in agrochemical formulation. Biomass can be converted to liquid through pyrolysis. Recent advancement in pyrolysis allows shorter heating time, i. e. <2 s at intermediate temperature of 400-600°C in oxygen-free condition. The produced liquid is known as bio-oil and is dark in colour, with energy density of 20 GJ/m3 and trans — ferrable using exiting oil tankers. It is used as boilers fuels and in specialty chemi­cals flavouring and colouring. Bio-oil can be upgraded using H2 or in catalytic environment it can be converted to BTX, MTBE and compatible transportation fuel (Klass 1998).

For ethanol production via fermentation, three types of biomass are employed. They are originated from sugar, starchy and lignocellulosic crops. For sugar crops, pretreatment is unnecessary, but for other crops the cell walls must be disrupted to expose the sugar polymers. The processes involved in ethanol production are pre­treatment, hydrolysis and fermentation and product separation through distillation. Contrarily, for direct biomass liquefaction, the biomass is not subjected to heat directly (Klass 1998). Direct liquefaction of biomass is in development stage and, namely, biomass-water slurry process, biomass-recycle oil slurries and hydroiodic acid. In recycled oil slurries, it requires sodium carbonate and CO gas at 250-450°C with 10-30 MPa pressure for conversion to liquid fuel with heating value of 33-34 MJ/kg. For the other process hyroiodic fluid is introduced at 127°C to form hydro­carbon at 60-70% yield. Hew et al. (2010) studied conversion of EFB into liquid product. The EFB-derived pyrolysis oil (bio-oil) is converted to liquid fuel, follow­ing Taguchi method. From the analysis, the optimum operating condition for the heterogeneous catalytic cracking process is at 400°C, 15 min of reaction time using 30 g of catalyst weight.

In 1900, Rudolf Diesel demonstrated a direct injection diesel engine fuelled with peanut oil. Ester-type biodiesel is produced catalytically from methanol or ethanol transesterification of triglycerides to methyl or ethyl esters. Its yield and purity depend on ratio of alcohol and triglycerides, catalyst type, temperature and purity of triglyceride. Modhar et al. (2010) investigated the blending of crude palm/crude rubber seed oil and their conversion to biodiesel. Optimum reaction conditions were determined and the conversion of methyl esters exceeded 98%. Biodiesel can be produced from low cost nonedible oils and fats. However most of these sources are of high free fatty acid content which requires two stage processes. The acid treat­ment step is usually followed by base transesterification since the later can yield higher conversions of methyl esters at shorter reaction time.