Bio-phenol production from lignin via TiO2/Al2O3 catalytic pyrolysis

Abstract

Lignin has emerged as a valuable raw material for the production of phenolic chemicals due to its unique structure, abundance, and renewable nature. Among various conversion techniques, enhancing the selectivity of phenolic products through catalytic pyrolysis has garnered significant attention. This study utilized a combination of TiO 2 and Al 2 O 3 as catalysts for lignin pyrolysis. Experimental results revealed that when lignin was pyrolyzed using a TiO 2 :Al 2 O 3 ratio of 2:1 at 500°C, the bio-oil yield peaked at 33.7 wt%, and the selectivity of phenolic products increased from 11.1 % to 35.2 %. Furthermore, employing the TA 1–1 catalyst (TiO 2 :Al 2 O 3 = 1:1) achieved a phenol yield of 40.2 mg/g. After five cycles of catalytic pyrolysis and regeneration, the composition and morphology of the TA 2–1 catalyst (TiO 2 :Al 2 O 3 = 2:1) remained unchanged, with its catalytic performance comparable to the initial use, indicating excellent crystal phase and regeneration stability. These findings provide valuable insights for the development of acid site catalysts tailored for lignin deconstruction to produce phenolic compounds. • Catalysts of various acid concentrations were made via coprecipitation. • Catalytic pyrolysis decreased methoxy phenols production significantly. • Lignin pyrolysis yields bio-oil at 33.7 wt% and phenol at 40.2 mg/g. • The regenerated catalyst still has good demethoxylation capacity.