Exploring catalytic pyrolysis of palm shell over HZSM-5 by gas chromatography/mass spectrometry and photoionization mass spectrometry

The catalytic pyrolysis characteristics of palm shell were investigated using pyrolysis-gas chromatography/mass spectrometry (py-GC/MS) and pyrolysis photoionization mass spectrometry (py-PIMS) methods. Temperature-programmed results and time-evolved profiles of major products, such as alkenes, aromatics, furans, and phenols were measured. Temperature and catalysts can effectively influence the pyrolysis products distribution. Two peaks of temperature-programmed results of furfural indicated that hemicellulose and cellulose depolymerized at different temperatures. Two decomposition pathways of lignin were proposed: the ether linkages between monomer units of lignin and the methoxy groups on the aromatic rings would break at different temperatures. With the presence of HZSM-5, the yields of alkenes and aromatics increased and that of oxygenates reduced because primary oxygenates from pyrolysis underwent catalytic deoxygenation and cracking to form light alkenes, which subsequently react with furans or other large alkenes to produce aromatic hydrocarbons. The catalytic effect was intensified as the HZSM-5-to-palm shell mixing ratio was increased. Deoxygenation index shows the maximum deoxygenation occurred in palm shell/HZSM-5 ratio = 1:2 at 500 degrees C