Pyrolyzer–GC/MS system-based analysis of the effects of zeolite catalysts on the fast pyrolysis of Jatropha husk

Abstract

Samples of Jatropha husk and cedar wood were catalytically pyrolyzed at 500°C using the zeolites H-USY, H-Mordenite, H-Beta, and H-ZSM-5 as catalysts. The products of the pyrolysis processes were analyzed using a pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS) system. The fast pyrolysis of the Jatropha husk sample in the presence of the zeolites produced aromatic hydrocarbons in greater amounts than those produced during the pyrolysis of the cedar sample. Jatropha husk exhibited specific reactivity during the catalytic fast pyrolysis process. Among the catalysts evaluated, the zeolite H-USY exhibited the highest activity as evidenced by the changes in the pyrolysis products. It also exhibited the highest selectivity with respect to monocyclic aromatic hydrocarbons (MAHs). However, the use of this catalyst also resulted in an increase in the formation of the solid residue remaining after the pyrolysis process, which comprised coke and polycyclic aromatic hydrocarbons (PAHs) such as naphthalene and phenanthrene. In contrast, coke and PAHs were produced in very small amounts when the zeolite H-Beta was used. Furthermore, its selectivity with respect to MAHs was lower than those of the zeolites H-USY and H-ZSM-5 when used in the Jatropha husk/zeolite weight ratio of 1:1. When catalytic fast pyrolysis was carried out at a Jatropha husk/zeolite weight ratio of 1:5, selectivity with respect to the MAHs increased drastically. However, there was no concomitant increase in the production of coke and PAHs. The fact that coke and PAHs were produced in smaller amounts during the fast pyrolysis of Jatropha husk when the zeolite H-Beta was used as the catalyst makes it attractive for increasing the yield of MAHs during the pyrolysis of biomasses.