National energy security and rising environmental concerns associated with fossil fuels have urged us to find out alternative sources for energy production. Biomass is widely accepted as a potential source of energy and it is the only renewable energy source that can provide liquid fuels. Biomass can be converted into fuels thermally and biologically. Primarily, thermal conversion of biomass is done through combustion, gasification or pyrolysis. At present, fast pyrolysis of biomass is getting more attention because of its high oil yield and high energy density compared to virgin biomass. Fast pyrolysis is a high temperature process in which biomass is thermally cracked into smaller compounds in an inert atmosphere at high heating rate. The vapor from this process is quickly condensed into liquid and this viscous liquid is called pyrolysis oil or bio-oil. Bio-oil is a chemically complex mixture of water, aldehydes, acids, alcohols, carbohydrates, ketones, phenols and other lignin fragments. The fuel properties of bio-oil are comparable with conventional fossil fuels. In addition, bio-oil can be used as a feedstock for many commodity chemicals. Many of the applications of bio-oil are limited because of some undesirable properties such as high pH, low heating value, high viscosity, and unstable. High reactivity of oxygenated compounds in bio-oil makes it very unstable.
Current studies are being focused in optimizing pyrolysis conditions, upgrading of bio-oil and finding more applications of bio-oil. Biomass feedstock has a great influence on the properties of bio-oil. In the present study, change in physical properties of bio-oil while varying pyrolysis conditions has been noticed. The change in properties is a result of the change in chemical composition of bio-oil. However, only a handful studies have studied the effect of operating parameters on individual compound. In this study, careful control of pyrolysis parameters, such as temperature, pressure, heating rate and pyrolyzing environment (hydrogen, helium, air) will be carried out to study the effect on the yield of individual component in the bio-oil. Switchgrass, pine wood, peanut hulls and poultry litter are selected as feedstocks. The selected feedstocks are agricultural wastes and they are selected because of their relative abundance in Alabama and in the U.S. in general. This study will lead us to determine optimal pyrolysis conditions for high quality bio-oil, which would make downstream processes easier and economical for fuel production. Pyrolysis studies will be carried out in a pyroprobe which is interfaced with a GC/MS. The probe contains a computer controlled heating element which holds finely grounded biomass in a quartz tube. Reactant gas carries the pyrolysis vapors from the probe to a trap which is resting in normal temperature. The trap adsorbs the condensed bio-oil components and the non-condensed vapors are purged with reactant gas. The adsorbed bio-oil is desorbed through GC/MS carrier gas and is directed to GC for analysis. Pyroprobe has a large range and a high precision for changing all the pyrolysis parameters.