Abstract
Furfural and 5-hydroxymethylfurfural stand out as bridges connecting biomass raw materials to the biorefinery industry. Their reductive transformations by hydroconversion are key routes toward a wide variety of chemicals and biofuels, and heterogeneous catalysis plays a central role in these reactions. The catalyst efficiency highly depends on the nature of metals, supports, and additives, on the catalyst preparation procedure, and obviously on reaction conditions to which catalyst and reactants are exposed: solvent, pressure, and temperature. The present review focuses on the roles played by the catalyst at the molecular level in the hydroconversion of furfural and 5-hydroxymethylfurfural in the gas or liquid phases, including catalytic hydrogen transfer routes and electro/photoreduction, into oxygenates or hydrocarbons (e.g., furfuryl alcohol, 2,5-bis(hydroxymethyl)furan, cyclopentanone, 1,5-pentanediol, 2-methylfuran, 2,5-dimethylfuran, furan, furfuryl ethers, etc.). The mechanism of adsorption of the reactant and the mechanism of the reaction of hydroconversion are correlated to the specificities of each active metal, both noble (Pt, Pd, Ru, Au, Rh, and Ir) and non-noble (Ni, Cu, Co, Mo, and Fe), with an emphasis on the role of the support and of additives on catalytic performances (conversion, yield, and stability). The reusability of catalytic systems (deactivation mechanism, protection, and regeneration methods) is also discussed.
Highlights
Fossil resources, petroleum, natural gas, and coal, have been the main source for the production of transportation fuels and chemicals in the past century and have played a crucial role in accelerating economic growth.[1,2] In 2016, about 85.5% of the energy consumed worldwide came from fossil resources.[3]
Pd is a highly active metal on which valuable chemicals and renewable fuels can be obtained via Review hydrogenation/hydrogenolysis of the pendent −CHO group and/or of the furan ring, or by condensation reactions
The products of the hydrogenation/hydrogenolysis routes involving the −CHO group, Furfuryl Alcohol (FOL), and MeF are obtained under mild reaction conditions using catalysts with a low loading of Pd
Summary
Review associated release of CO2 in the atmosphere has been the source of climate change and global warming.[4,5] For these reasons, nonedible biomass such as lignocellulose has attracted attention in the last decades as a renewable alternative.[6] It is an abundant, sustainable, and a cost-efficient source of organic chemicals and liquid biofuels,[7,8] and because the production of vegetals consumes CO2, it is environmentally more benign than the exploitation of fossil resources.[5]
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have