Recovery of bio-fuels from agricultural residues

Abstract

De-oiled cakes, a source of biomass in the form of agriculture residue, could be an ideal source
for the production of bio fuels that can be used as a substitute for the existing conventional fossil
fuels which are at the verge of getting extinct. Though there are many biomass conversion
processes like pyrolysis, combustion, gasification, liquefaction, hydrogenation, pyrolysis has
gained special attention as it can convert biomass directly into solid, liquid and gaseous products
by thermal decomposition in absence of oxygen. In this study, neem, mustard and mahua deoiled
cakes were pyrolysed at a temperature of 300 0C to 700 0C at a heating rate of 25 0C /min.
The maximum liquid yield obtained was 40.23% at a pyrolysis temperature of 400 0C for neem
cake, 53.26% at a pyrolysis temperature of 550 0C for mustard cake and 41.2 % at a pyrolysis
temperature of 550 0C for mahua cake. The effect of temperature on pyrolysis of liquid product,
char, gaseous product and reaction time were studied. The various characteristics of liquid
product obtained were identified on the basis of standard test methods. Effect of heating rate on
the mass loss for all the raw materials were examined using the thermo gravimetric analysis
profiles (TGA). The empirical formulas of the bio-oil with heating value were established. The
chemical compositions of the bio-oils and char were investigated using FTIR, SEM, EDX and
GC-MS. Further structural analysis of pyrolysis oil was conducted using 1H-NMR spectroscopy.
The fuel properties of the bio-oil such as kinematic viscosity, flash point, fire point, cloud point,
pour point and specific gravity were also determined. Engine performance, combustion and
emission characteristics of blends of mustard cake pyrolytic oil with diesel (10%, 20%, 30%,
40%, 50%) were also studied. The chemical characterization and engine performance showed
that bio-diesel of 30% blend can be substituted with diesel fuel and the bio-oil obtained from
these raw materials may be potentially valuable as chemical feedstock.