Selective pyrolysis of Organosolv lignin over zeolites with product analysis by TG-FTIR

摘要

Organosolv lignin has been selected to investigate the thermal behavior of lignin over zeolites by using a thermogravimetric analyzer coupled with a Fourier-transform infrared spectrometer (TG-FTIR). The chemical structure of this lignin has been determined by ~1H NMR to obtain the distribution of main functional groups such as methoxyl groups and free aliphatic and phenolic hydroxyl groups. All three zeolite catalysts tested, HZSM-5, H-β, and USY, exerted significant influences on the dehydration reaction in the initial stage, the deoxygenation reaction of oxygenated compounds such as methanol and phenols, and the char-forming process during lignin pyrolysis in the range 30-800℃. The dehydration reaction was enhanced in the order USY ＞ HZSM-5 ＞H-β, while char formation was suppressed in the reverse order. The presence of HZSM-5 and H-β catalyzed the conversion of both oxygenated compounds and chars into the low-molecular-weight gases CO, CO_2, and methane. The addition of USY clearly aided decomposition of the oxygenated compounds, but had little effect on the char degradation.