Investigation of pyrolysis behaviour of corn cob

Biomass is the only renewable and most abundant energy source. Today intensive studies have been undertaken on chemicals and power generation, including bio fuels from biomass. Production of gas, liquid, aqueous organic compounds and solid products (char) from biomass by pyrolysis technology is known since the first ages. Product yields obtained by this method depend on the techniques applied and pyrolysis variables; and it has been observed that the product yields reported so far reflect mostly the results obtained in the systems that are open in the atmosphere. In this study, pyrolysis of corncob, which is an agricultural biomass waste, was investigated in closed environment. In the pyrolysis experiments, use of mini closed aluminium reaction vessels by virtue of their high thermal conductivity, were preferred. Effects of pyrolysis temperature and reaction time on the yields of the major products were searched. To characterize corncob biomass, proximate and ultimate analyses, FTIR spectroscopy and thermal gravimetric analysis were also made. After the experiments conducted at temperatures up to 450°C, it is observed that the highest liquid and gas yields are obtained from corncob at 450°C in 5 minutes duration period. Paralleling to the increases in liquid and gas yields with temperature and pyrolysis time, total conversion ratios also increase. At the end of 5 minutes retention time, total conversion ratios were found as 32, 41 and 66 % at temperatures of 350, 400 and 450°C respectively. When the kinetic parameters found by fitting conversion ratios and retention times with a variety of widely used models are considered, it is concluded that global thermal degradation step of corncob pyrolysis can be described by n?th order reaction rate equation and three-dimensional (Jander) diffusion equation. The values of apparent activation energies were in accordance with those reported in similar studies on some biomass samples. Keywords: Energy, Corncob, Pyrolysis, Closed system, Product yield.