Efficient Conversion of Lignin to Aromatics via Catalytic Fast Pyrolysis over Niobium-Doped HZSM-5

Abstract

A niobium-doped HZSM-5 (H[Nb]ZSM-5) was prepared by a hydrothermal synthesis method. The morphology, phase structure, composition, pore structure, and acid content of the catalyst were characterized using a series of analysis techniques such as scanning electron microscope (SEM), energy-dispersive X-ray (EDX), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption-desorption, and temperature programmed desorption measurements (NH3-TPD). The H[Nb]ZSM-5 catalyst fully remained within the crystal framework and pore structure of HZSM-5. Meanwhile, introduction of niobium (V) endowed the catalyst with both Lewis acid and Bronsted acid sites. Catalytic fast pyrolysis (CFP) of alkali lignin was carried out through a pyrolysis and gas chromatography-mass spectrometry (Py-GC/MS) at 650 °C and atmospheric pressure. The results indicated that H[Nb]ZSM-5 can efficiently and selectively convert lignin into monoaromatic hydrocarbons (MAHs), compared to the control HZSM-5. Catalyzed by H[Nb]ZSM-5, the content of MAHs and aliphatic hydrocarbons reached 43.4% and 20.8%, respectively; while under the catalysis of HZSM-5, these values were 35.5% and 3.2%, respectively. H[Nb]ZSM-5 remarkably lowered the phenol content to approximately 2.8%, which is far lower than the content (24.9%) obtained under HZSM-5 catalysis.

Enhanced aromatics production through Fe and HZSM-5 catalytic lignin pyrolysis with magnetic field assistance

“…The catalyst surface frequently serves as a location where oxygen-containing large molecules result in deactivation through coking and reduced selectivity toward aromatics. 13,14 Hence, it is essential to pre-pyrolyze the initial volatiles from lignin. This process converts the macromolecular oxygen-containing intermediates into smaller compounds and hydrogen-rich gases, thereby enhancing the efficiency of mass transfer for these volatiles on HZSM-5.…”

Hydrodeoxygenation of Oxygenates Derived from Biomass Pyrolysis Using Titanium Dioxide-Supported Cobalt Catalysts

“…In the past decade, the technology of LCB valorization has focused on the production of bioethanol or value-added chemicals from the cellulose and hemicellulose fractions [7]. At the same time, the lignin portion is mostly discarded in the waste stream of the refinery process and burnt for internal energy [8]. Since the lignin fraction is rich in aromatic compounds, it represents a promising source of feedstock to produce bio-based aromatics [9][10][11].…”