Catalytic upgrading of lignin derived bio-oil model compound using mesoporous solid catalysts

Downstream processing of lignin derived feedstock into end products

This review provides critical analysis on various downstream processes to convert lignin derived feedstock into fuels, chemicals and materials.

Low temperature hydrodeoxygenation of guaiacol into cyclohexane over Ni/SiO2 catalyst combined with Hβ zeolite

Hydrodeoxygenation (HDO) of guaiacol to cyclohexane, important for bio-oil upgrading, is usually performed at high reaction temperature (≥200 °C). In this work, low temperature transformation of guaiacol to cyclohexane was achieved at 140 °C over non-noble metal Ni/SiO₂ and various zeolites. Among zeolites tested (HUSY, HMOR, Hβ, HZSM-5, SAPO-34), Hβ zeolite exhibited superior catalytic activity due to its appropriate pore structure and acid strength. The open pore with three-dimensional structure of Hβ facilitates the diffusion of guaiacol and intermediates. Meanwhile, weak acid strength of Hβ efficiently reduces the competitive adsorption of guaiacol, and then promotes the dehydration of intermediate 2-methoxycyclohexanol. Moreover, the catalytic performance in guaiacol HDO to cyclohexane is also closely related to Si/Al ratio of Hβ. Owing to its moderate acid density, the maximum yield of cyclohexane reaches 91.7% on Hβ(Si/Al = 50) combined with Ni/SiO₂ at 140 °C, which is the lowest temperature ever reported over non-noble metal catalysts.

Hydrodeoxygenation (HDO) of guaiacol to cyclohexane, important for bio-oil upgrading, is usually performed at high reaction temperature (≥200 °C) over non-noble metal catalysts.

Bio-oil from fast pyrolysis of lignin: Effects of process and upgrading parameters

Effects of process parameters on the yield and chemical profile of bio-oil from fast pyrolysis of lignin and the processes for lignin-derived bio-oil upgrading were reviewed. Various process parameters including pyrolysis temperature, reactor types, lignin characteristics, residence time, and feeding rate were discussed and the optimal parameter conditions for improved bio-oil yield and quality were concluded. In terms of lignin-derived bio-oil upgrading, three routes including pretreatment of lignin, catalytic upgrading, and co-pyrolysis of hydrogen-rich materials have been investigated. Zeolite cracking and hydrodeoxygenation (HDO) treatment are two main methods for catalytic upgrading of lignin-derived bio-oil. Factors affecting zeolite activity and the main zeolite catalytic mechanisms for lignin conversion were analyzed. Noble metal-based catalysts and metal sulfide catalysts are normally used as the HDO catalysts and the conversion mechanisms associated with a series of reactions have been proposed.

Upgrading of anisole using in situ generated hydrogen in pin to plate pulsed corona discharge

In this paper, corona discharge plasma was used for upgrading of anisole as a model compound of lignin derived bio-oil. The required H₂ was generated in situ via methyl decomposition to H₂.