State of the Art and Perspectives in Catalytic Conversion Mechanism of Biomass to Bio-aromatics

Abstract

Research on biomass decomposition and transformation has attracted widespread attention from academia to industry worldwide, aiming to harvest bio-aromatics from the abundant renewable biomass resource. However, the complexity of the structure and composition of biomass makes its conversion into bio-aromatics a very challenging task. Hence, it is necessary to understand in depth the mechanism of biomass conversion to bio-aromatics with higher selectivity. Although considerable progress has been achieved on the development of bio-aromatics from biomass, the detailed process and reaction mechanism for the bioaromatics synthesis has lacked a complete summary. This work reviews the recent advances in the conversion of biomass to bioaromatics, including biomass gasification, pyrolysis, and hydrolytic fermentation, etc. Various biomass sources and biomass-derived model compounds as examples were used to illustrate the effect of different raw materials on the yield of bio-aromatics. Subsequently, this review summarizes the influence of different catalysts on the synthesis of bio-aromatics and the metal-modified HZSM-5 catalysts exhibited a higher bio-aromatics yield compared with those of other catalysts. Finally, the reaction mechanism of biomass to bio-aromatic hydrocarbons via different reaction routes was discussed in detail. The aim is for the conversion mechanism presented in this work to provide a reference for the efficient conversion of bio-aromatics from biomass in the future.

Sustainable biomass hydrodeoxygenation in biphasic systems

“…106,107 Lignin as a model compound for native biomass is a three-dimensional amorphous network composed of methoxylated phenyl-propane units, which consist of a great number of etheric C-O linkages (mainly 4-O-5, α-O-4 and β-O-4) and C-C linkages. [108][109][110][111] During lignin upgrading, it is necessary to cleave more C-O-C bonds to produce the target compound under specific reaction conditions rather than cleaving C-C bonds to cause ring-opening reactions of hydrocarbons (e.g. hexane or heptane).…”

Hydrogen Spillover‐Enhanced Heterogeneously Catalyzed Hydrodeoxygenation for Biomass Upgrading

“…[107] In addition to Ru-based catalysts, Pt-based catalysts are also selective for aromatics through modifying surface and adjusting reaction conditions. [108] Pt/TiO 2 and Pt/C were utilized for cresol HDO at 796 and 896 °C. [98] The results showed that Pt/TiO 2 exhibited higher catalytic activity and selectivity for toluene at 896 °C compared to Pt/C, which was attributed to the fact that when Pt was loaded on TiO 2 , it promoted the dissociation and spillover of H 2 , and the formation of oxygen vacancies by the spillover of active hydrogen on the metal phase, [109] which facilitated the deoxygenation of m-cresol and increased the selectivity for aromatics, as shown in Figure 14b, c.…”

“…In addition to Ru‐based catalysts, Pt‐based catalysts are also selective for aromatics through modifying surface and adjusting reaction conditions [108] . Pt/TiO 2 and Pt/C were utilized for cresol HDO at 796 and 896 °C [98] .…”

Catalytic Fast Pyrolysis of Lignocellulosic Biomass to Benzene, Toluene, and Xylenes

“…The pyrolysis vapor must condense quickly to avoid unwanted secondary reactions such as cracking. Alkali and alkaline earth metal ions in biomass feed pose substantial challenges to the process (addressed in Pretreatment) [17,[19][20][21][22][23][24][25][26][27][28][29][30][31][32][33].…”