Upgrading of Bio‐Oil Model Compounds and Bio‐Crude into Biofuel by Electrocatalysis: A Review

Abstract

Limited availability of fossil energy and serious environmental pollution have caused the emergence of bio‐oil, which can serve as an alternative and promising green energy source. However, bio‐oil generated from the rapid pyrolysis of biomass cannot be utilized immediately owing to its corrosivity, instability, and low heating value. Herein, the electrocatalytic hydrogenation (ECH) process towards bio‐oil upgrading is reviewed. Specifically, the ECH integrates the advantages of mild operating conditions, no petrochemically derived hydrogen and good controllability. The influence of different factors on the conversion of bio‐oil components and product selectivity in the ECH process are presented comprehensively. In addition, various reaction mechanisms are discussed in the designed ECH systems. Finally, some challenges need to be further overcome for real bio‐oil reduction in the ECH process: exploration of efficient multifunctional electrocatalysts for specific bio‐oil components and determination of the dominant steps in the complicated reaction path network.

Controlling Transformation of Sorbitol into 1-Hexanol over Ru-MoOx/Mo2C Catalyst via Aqueous-Phase Hydrodeoxygenation

“…As the only renewable organic carbon source, abundant biomass has long been established and developed to partially substitute conventional fossil resources in the production of value-added biochemicals and biomaterials. − Many new efforts have focused on producing higher alcohols from hemicellulose, cellulose, and sugar polyols using catalytic technologies. − Biomass was directly depolymerized and transformed into C2-C10 linear and cyclic alcohols through retro-aldol condensation and subsequent carbon–carbon coupling under harsh supercritical methanol and CuMgAlO x catalyst. , With the assistance of H 2 SO 4 , the cellulose and hemicellulose were slowly converted into alcohol mixtures of isomeric hexanols and pentanols in the water–solvent biphasic system, respectively, via the selective cleavage of C–O bonds rather than breaking C–C bonds over the Ir-ReO x /SiO 2 catalyst. , However, the main technological obstacles involved the low selectivity of target 1-hexanol and the complicated product distribution, leading to these synthesis strategies being still far from industrial application.…”

“…This indicated that the removal of terminal hydroxyl groups of sorbitol was effectively suppressed by introducing MoO x species into 2Ru/Mo 2 C. However, in the absence of metallic Ru, 2MoO x /Mo 2 C exhibited poor HDO activity and mainly produced oxygenated intermediate compounds. As a consequence, it was necessary to improve the hydrogenolysis activity of the 2MoO x /Mo 2 C catalyst by the incorporation of metallic Ru, which was beneficial to the further transformation of intermediate products . Subsequently, with the increase of the Ru loading from 2.0 to 4.0 wt %, the yield of 1-hexanol decreased greatly from 23.5 to 12.4%, while the yield of 1-hexane raised from 24.9 to 36.9%.…”

“…As a consequence, it was necessary to improve the hydrogenolysis activity of the 2MoO x /Mo 2 C catalyst by the incorporation of metallic Ru, which was beneficial to the further transformation of intermediate products. 17 Subsequently, with the increase of the Ru loading from 2.0 to 4.0 wt %, the yield of 1-hexanol decreased greatly from 23.5 to 12.4%, while the yield of 1-hexane raised from 24.9 to 36.9%. It could be inferred that the excess loading of Ru facilitated deep oxygen removal, leading to the product distribution shift to 1hexane.…”

Co3Mo3N as an alternative for noble-metal catalysts in hydrodeoxygenation of methyl palmitate to diesel range hydrocarbons

“…The utilization of traditional fossil resources leads to large CO 2 and other polluting gas emissions, causing some problems such as global warming and air pollution. 1,2 In addition, the large-scale use of limited fossil fuels as a major energy source will cause depletion inevitably. Therefore, it is imperative to develop renewable non fossil energy sources.…”

Efficient Hydrodeoxygenation of Lignin-Derived Phenols to C6+ Cycloalkanols/Cycloalkanes over Magnetic Carbon-Encapsulated Nickel Nanospheres

“…The detriments of carbon emission have prompted the demands of clean energy to replace primary energy, which have become increasingly urgent. Non-food biomass waste as one clean energy would be a low-cost solution for this issue. − Bio-oil as a product of the biomass conversion could be utilized as a liquid energy. , However, the high oxygen content and low heating values would restrict it to be an alternative of fuels. Generally, hydrodeoxygenation (HDO) could be an effective process for the upgradation of lignin. − A series of heterogeneous catalysts have been studied for the HDO process, which loaded noble or non-precious metals. , Noble-metal-based catalysts that relied on their excellent HDO activity have received attention, but widespread industrial applications are confined because of their insufficient resource and high cost.…”