EP-4737446-A1 - PROCEDURE FOR THE CONVERSION OF GAMMA-KETOACIDS TO GAMMA-LACTONES VIA PHOTOTHERMAL CATALYSIS

Abstract

The present invention relates to a procedure for the conversion of γ-ketoacids , such as levulinic acid, to γ-lactones in the presence of a Ni-based catalyst and isopropanol as hydrogen source and solvent via photothermal process using UV to NIR light as energy source (such as solar and laser). This is a sustainable, economically and environmentally viable procedure that has demonstrated nearly complete conversion in less than 2h under moderate conditions.

Inventors

• Fons Cervera, Arnau
• SEPÚLVEDA MARTÍNEZ, Borja
• Serrà Ramos, Albert
• Gómez Valentín, Elvira
• NOGUES SANMIQUEL, Josep
• Bujaldón Carbó, Roger

Assignees

• Consejo Superior de Investigaciones Científicas (CSIC)
• Universitat de Barcelona
• Fundació Institut Català de Nanociència i Nanotecnologia (ICN2)
• Institució Catalana de Recerca i Estudis Avançats (ICREA)

Dates

Publication Date

20260506

Application Date

20241030

Claims (13)

1. Procedure for the conversion of a γ-ketoacid to the corresponding γ-lactone via photothermal catalysis comprising contacting the γ-ketoacid with a Ni-based catalyst and with isopropanol, which is used as a hydrogen source and solvent, and photothermally heating at a temperature between 100 and 150°C by applying UV to NIR light with wavelength between 350 to 2000 nm in a hermetically sealed reactor.
2. Procedure, according to claim 1, wherein the Ni-based catalyst is Raney Ni.
3. Procedure, according to claim 1, wherein the Ni-based catalyst is a Ni-P-based catalyst.
4. Procedure, according to claim 3, wherein the Ni-based catalyst is a graphite/Ni-P catalyst.
5. Procedure, according to any of the preceding claims, wherein sunlight radiation is used as light source.
6. Procedure, according to claims 1 to 3, wherein a laser with emission in the range between 450 nm to 1300 nm is used as light source.
7. Procedure, according to any of the preceding claims, wherein the concentration of the γ-ketoacid in the solution of isopropanol is between 0.1 and 1.5 M.
8. Procedure, according to any of the preceding claims, wherein the amount of catalyst is between 0.1 and 5 %wt with respect to the γ-ketoacid.
9. Procedure, according to any of the preceding claims, wherein the reaction time is between 60 and 120 min.
10. The procedure, according to any of the preceding claims, wherein the temperature of the procedure is between 100 and 140°C.
11. Procedure, according to claim 1, wherein the procedure comprises contacting the γ-ketoacid with the catalyst Raney Ni photothermally heated at a temperature between 130 and 150 °C, more preferably at 140°C, during a time between 80 and 120 min.
12. Procedure, according to claim 1, wherein the procedure comprises contacting the γ-ketoacid with the catalyst graphite/Ni-P photothermally heated at a temperature between 100 and 120 °C during a time between 80 and 120 min.
13. The procedure, according to any of the preceding claims, wherein the γ-ketoacid is levulinic acid and the obtained γ-lactone is γ-valerolactone.

Description

The invention relates to a sustainable procedure to obtain γ-lactones, more particularly, γ-valerolactone, which, apart from being a platform to other high-value chemicals, it has applicability itself as a biofuel, green solvent or even in perfumery. γ-lactones are synthesized through a hydrogenation reaction from γ-ketoacids via photothermal catalysis. BACKGROUND ART Reducing the overreliance on fossil fuels and curbing the steady rise of CO2 emissions has grown into a pressing global priority to address the climate crisis. In this pursuit, biomass valorization emerges as an engaging approach for transitioning away from fossil fuels towards a more sustainable economy. Biomass originates as a residue from activities as diverse as agriculture, livestock-related industries, and the management of forested areas, which regards it as the only renewable raw material that can be readily converted into organic molecules. Lignocellulosic wastes indeed hold significant interest in their derivatization to biofuels and related value-added compounds. Recognizing this perspective, forest management must transcend ecological considerations alone and adopt a holistic approach. Forests can serve not solely as ecosystems but also as clean and sustainable factories. Consequently, the development of novel strategies that pave the way towards a biomass-based system, in which bioeconomy and circularity represent the main principles, stands as a prime objective. The composition of lignocellulosic biomass majorly comprises cellulose (35-50%), hemicellulose (20-40%) and lignin (10-25%). The formers can be transformed into synthetic building blocks of interest, such as 5-hydroxymethylfurfural (5-HMF) and levulinic acid (LA), through successive physicochemical processes that have been extensively reported. γ-Valerolactone (GVL) is one of the most promising biomass derivatives, considering its applications as biofuel, alternative greener solvent, precursor of biopolymers, as well as its value in perfumery. Accessing an economically viable process for a sustainable production from biomass has inevitably become a pivotal area of research. The synthesis of γ-valerolactone implies the hydrogenation of the ketone group of levulinic acid, which is generally conducted with molecular hydrogen, and its subsequent intramolecular esterification. The main production of hydrogen, however, still relies on non-renewable sources, which critically hampers the sustainability expected from this procedure. This method also involves working under high pressure to promote the reaction, which complicates the requirements of the facilities and industrial plants. A well-known strategy to circumvent these factors is the incorporation of alternative biomass-derived reducing agents in which hydrogen is supplied/generated in situ. Two prime examples are formic acid, which decomposes catalytically into hydrogen and carbon dioxide, and alcohols, particularly secondary ones, which undergo a catalytic hydrogen transfer via the Meerwein-Ponndorf-Verley reaction. The former is especially attractive since it is produced equimolarly along with levulinic acid during the acid-mediated rehydration and subsequent oxidation of 5-HMF. Thus, it would be continuously supplied into the reaction medium in a one-pot synthetic strategy starting from cellulose, apart from being a biomass-derived reagent. Another key challenge to be considered for this process is the high energy consumption associated with elevated working temperatures to carry out the hydrogenation reaction. The nature and characteristics of the catalyst are particularly decisive at this point. A vast range of catalytic platforms based on diverse noble and non-noble metals have been reported so far [1) Valentini, F.; Marrocchi, A.; Vaccaro, L. Adv. Energy Mater. 2022, 12, 2103362. 2) Hijazi, A.; Khalaf, N.; Kwapinski, W.; Leahy, J. J. RSC Adv. 2022, 12, 13673-13694.]. The scope of temperatures needed is equally varied, but generally goes up to 180 °C, which makes it highly energy demanding. Therefore, developing new technologies to reduce energy consumption is a major challenge. In this context, photothermocatalytic reactions could provide an interesting alternative to drastically reduce the necessary input energy. Photothermocatalysis is based on the use of an intense light source to produce the heat necessary for the catalyzed reaction to progress. Photothermal catalysis can follow two different catalytic pathways: thermochemical or photochemical. In the thermochemical pathway, the photothermal catalyst interacts with the incident light and then converts the photon energy into thermal energy by exciting vibrational states. Noble metal plasmonic nanoparticles and carbonaceous materials are often used as photothermal catalysts [1) Fang, S.; Hu, Y. H. Chem. Soc. Rev. 2022, 51, 3609-3647. 2) Zhang, J.; Chen, H.; Duan, X.; Sun, H.; Wang, S. Mater. Today 2023, 68, 234-253.]. Noble metals nanostructures can generate local