CORESTA Meeting, Smoke/Technology, Innsbruck, 1999, ST20

Experimental investigation of formation of aromatic hydrocarbon from pyrolysis of cellulosic materials

Philip Morris USA, Research Center, Richmond, VA, USA
The major chemical pathway to produce aromatic hydrocarbons in the pyrolysis followed by flaming combustion of biomass is high temperature secondary reactions of the primary pyrolysis products. The second and less explored route that is more pertinent to lower temperature smoldering combustion, is the evolution of aromatics from the remaining char as it is further aromatized with increasing pyrolysis temperature. In this study, the pyrolysis of cellulosic materials with emphasis on the formation of aromatic hydrocarbons from the second route was investigated. Experimental work was mostly carried out in a TG/DSC/MS analyzer. In order to reduce the formation of hydrocarbons from the secondary reactions of the primary pyrolysis products, small sample size, i.e ., 2-10 mg, high helium flow rate of 150 ml/min, and heating rates of less than 100°C/min were used. Identities and relative quantities of masses detected by TG/DSC/MS analyzer was confirmed by GC/MS using a CDS Pyroprobe. Under slow heating conditions which is typical of thermal analyzers, hydrocarbon products begin to evolve above 350°C, where the primary decomposition of cellulosic materials has completed and the remaining char has began the carbonization / aromatization process. Detectable products above 600°C in our thermal analyzer are methane, benzene, and hydrogen. Some kinetic parameters for the formation of hydrocarbon products are deduced from the exprimental findings and discussed in this presentation.