The Role of Copper in the Hydrogenation of Furfural and Levulinic Acid

Currently, there is a great interest in the development of sustainable and green technologies for production of biofuels and chemicals. In this sense, much attention is being paid to lignocellulosic biomass as feedstock, as alternative to fossil-based resources, inasmuch as its fractions can be transformed into value-added chemicals. Two important platform molecules derived from lignocellulosic sugars are furfural and levulinic acid, which can be transformed into a large spectrum of chemicals, by hydrogenation, oxidation, or condensation, with applications as solvents, agrochemicals, fragrances, pharmaceuticals, among others. However, in many cases, noble metal-based catalysts, scarce and expensive, are used. Therefore, an important effort is performed to search the most abundant, readily available, and cheap transition-metal-based catalysts. Among these, copper-based catalysts have been proposed, and the present review deals with the hydrogenation of furfural and levulinic acid, with Cu-based catalysts, into several relevant chemicals: furfuryl alcohol, 2-methylfuran, and cyclopentanone from FUR, and gamma-valerolactone and 2-methyltetrahydrofuran from LA. Special emphasis has been placed on catalytic processes used (gas- and liquid-phase, catalytic transfer hydrogenation), under heterogeneous catalysis. Moreover, the effect of addition of other metal to Cu-based catalysts has been considered, as well as the issue related to catalyst stability in reusing studies.

Automated summary

There is currently a strong interest in sustainable and green technologies for the production of biofuels and chemicals. Lignocellulosic biomass is being researched as an alternative to fossil resources, as its components can be transformed into valuable chemicals. Furfural and levulinic acid, derived from lignocellulosic sugars, are important platform molecules that can be converted into a variety of chemicals. Copper-based catalysts have been proposed as a cheaper alternative to the scarce and expensive noble metal catalysts commonly used. This review focuses on the hydrogenation of furfural and levulinic acid using Cu-based catalysts, and the production of various chemicals such as furfuryl alcohol and gamma-valerolactone.