In-line Catalytic Cracking of Kraft Lignin Pyrolysis Vapors over Modified Niobium Acid

In this study, modified niobium acid was prepared by calcination method. The catalytic pyrolysis and pyrolysis product of kraft lignin were analyzed by Py-GC/MS at 650 ℃. The modified niobium acid (Nb-350) was characterized by FT-IR, BET, XPS and NH₃-TPD. The effects of catalyst-to-lignin weight ratio, pyrolysis temperature, pyrolysis time and heating rate on kraft lignin CFP were explored. FT-IR and XPS analysis showed that the crystallization water in the modified niobium acid decreased during the calcination process. BET analysis showed that the pore volume and mesoporous ratio of Nb-350 increased. NH₃-TPD showed that Nb-350 has weak acid sites. Pyrolysis products of kraft lignin mainly contained benzene, toluene, methyl phenol and methoxyphenols. Nb-350 promotes the yield of phenols (up to 85%). The pyrolysis parameters (pyrolysis temperature: 650 ℃, pyrolysis time: 40 s, catalyst-to-lignin ratio: 4) optimized to improve the yield of phenols and aromatic hydrocarbons.