Transfer Hydrogenation Of Levulinic Acid Research Articles

Ferrocene-functionalized zirconium-oxo clusters for achieving high-performance thermocatalytic redox reactions

The Zr(IV) ions are easily hydrolyzed to form oxides, which severely limits the discovery of new structures and applications of Zr-based compounds. In this work, three ferrocene (Fc)-functionalized Zr-oxo clusters (ZrOCs), Zr9Fc6, Zr10Fc6 and Zr12Fc8 were synthesized through inhibiting the hydrolysis of Zr(IV) ions, which show increased nuclearity and regular structural variation. More importantly, these Fc-functionalized ZrOCs were used as heterogeneous catalysts for the transfer hydrogenation of levulinic acid (LA) and phenol oxidation reactions for the first time, and displayed outstanding catalytic activity. In particular, Zr12Fc8 with the largest number of Zr active sites and Fc groups can achieve > 95% yield for LA-to-γ-valerolactone within 4 h (130 °C) and > 98% yield for 2,3,6-trimethylphenol-to-2,3,5-trimethyl-p-benzoquinone within 30 min (80 °C), showing the best catalytic performance. Catalytic characterization combined with theory calculations reveal that in the Fc-functionalized ZrOCs, the Zr active sites could serve as substrate adsorption sites, while the Fc groups could act as hydrogen transfer reagent or Fenton reagent, and thus achieve effectively intramolecular metal–ligand synergistic catalysis. This work develops functionalized ZrOCs as catalysts for thermal-triggered redox reactions.

Construction of electron-deficient zirconium sites for the efficient catalytic transfer hydrogenation of levulinic acid

Zirconium-derived catalyst with abundant Lewis acid-base pairs has earned it a place of prominence for the catalytic upgrade of bio-based carbonyls to valuable chemicals and fuels through catalytic transfer hydrogenation (CTH) reaction. However, the low catalytic efficiency of Zr-based catalysts urgently needs to be improved to meet the criterion for their industrial deployment. In this contribution, tungstophosphoric acid (HPW) was demonstrated as an effective modifier to the electronic structure of the pristine polyacrylonitrile and lignin-supported Zr nanofiber (Zr-Lig@PAN) to boost the CTH of levulinic acid (LA) into γ-valerolactone (GVL). Especially, an impressive GVL formation rate of 32.5 mmol·g−1·h−1 was implemented over Zr/HPW0.75g-Lig@PAN, significantly prevailing over the previous reported Zr-based catalysts for the CTH of LA or its ester to GVL. Mechanistic investigations well demonstrated that the superior electron-accept ability of HPW allowed the construction of electron-deficient Zr sites, which is beneficial to the adsorption and activation of LA and isopropanol, thus boosting the CTH reaction. These findings open up a new avenue to design efficient Zr-based catalysts for the CTH reaction by elaborately tuning the electronic structure of the catalyst in the presence of a second metal.

Surface-sealing encapsulation of phosphotungstic acid in microporous UiO-66 as a bifunctional catalyst for transfer hydrogenation of levulinic acid to γ-valerolactone.

The efficient production of γ-valerolactone (GVL) from renewable lignocellulose that is synthesized in plants by photosynthesis to replace the declining fossil resources conforms to the principles of circular economy. Compared to direct hydrogenation by H2 molecules, catalytic transfer hydrogenation (CTH) of levulinic acid (LA) and/or its esters to GVL with organic alcohols as a hydrogen source is a much milder route. The synergistic catalysis between Lewis and Brønsted acids is indispensable in the CTH process. Considering that unsaturated coordinated Zr species could act as Lewis acid sites and phosphotungstic acid (PTA) could dissociate protons as Brønsted acid sites, UiO-66 (Zr) was thus "acidified" by encapsulating PTA in its channels to tune the ratio of Brønsted to Lewis acid sites as a bifunctional catalyst so as to better understand the catalytic structure-performance relationship in the CTH process. To address the dilemma of encapsulated PTA that is prone to leach, a rapid surface sealing strategy was adopted to establish a polyimide (PI) coating over the surface of UiO-66 introducing a space confinement effect via an anhydride-amine coupling reaction. The as-synthesized PTA/UiO-66@PI catalyst exhibited 100% of LA conversion, a 93.2% of GVL yield and high recyclability for at least five consecutive cycles. Moreover, a reaction pathway followed by esterification, hydrogenation and dealcoholization as well as a catalytic hydrogenation mechanism based on intermolecular hydride β-H transfer were proposed. Current work not only provides a high-performance and high-stability catalytic system to selectively produce GVL from LA or its esters, but also sheds light on the catalytic mechanism of the CTH process at the molecular level.

Catalytic transfer hydrogenation of levulinic acid to gamma-valerolactone over a zirconium-based FDCA hybrid: insights into the effect of heteropoly acids

A schematic for CTH of LvA into GVL over an acid–base multifunctional Zr-FDCA-HPWO hybrid.

Promoted catalytic vapor phase transfer hydrogenation of levulinic acid to γ‐valerolactone by coordinated size effect and acid property of bimetallic Ni/ CeO 2 catalyst

Promoted catalytic vapor phase transfer hydrogenation of levulinic acid to γ‐valerolactone by coordinated size effect and acid property of bimetallic Ni/ <scp> CeO ₂ </scp> catalyst

Bifunctional Acid‐Base Zirconium Phosphonate for Catalytic Transfer Hydrogenation of Levulinic Acid and Cascade Transformation of Furfural to Biofuel Molecules

AbstractThe production of biofuels, such as furfural ether and γ‐valerolactone (GVL) from biomass platform chemicals furfural (FFA) and Levulinic acid (LA) is of significant interest. In this study, a nanoporous inorganic‐organic Zr−phosphonate catalyst (ZrNPO3) was synthesized and employed in the selective production of GVL (98.2 %) via catalytic transfer hydrogenation of LA. The catalyst containing acid‐base sites was further used to produce biofuel molecules like GVL and furfuryl ether under a mild reaction condition via cascade furfural transformation. The GVL selectivity was further improved using phosphotungstic acid@ZrNPO3. The catalytic optimization studies were combined with poisoning studies and the detailed physicochemical characterization to acquire insight into the structure‐activity correlation and reaction mechanism. The synergistic presence of the Lewis acidity and basicity on the catalyst was responsible for its remarkable activity. Designing a single catalyst for the one‐pot tandem transformation of FFA to GVL would be highly motivating for catalysis researchers and industrialists.

Simultaneous Coordination of Zn(II) and Zr(IV) to d-Amino Acid Oxidase: Highly Efficient Catalytic Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone

Simultaneous Coordination of Zn(II) and Zr(IV) to <scp>d</scp>-Amino Acid Oxidase: Highly Efficient Catalytic Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone

Sustainable metal-lignosulfonate catalyst for efficient catalytic transfer hydrogenation of levulinic acid to γ-valerolactone

Production of γ-valerolactone (GVL) from biomass-derived platform levulinic acid (LA) via catalytic transfer hydrogenation (CTH) over renewable lignosulfonate-derived catalyst is reported herein. Lignosulfonate-derived catalysts were prepared by assembled Zr-metals with sodium lignosulfonate (LigS) derived from the industry paper waste. The resulting Zr-LigS catalyst exhibited excellent catalytic performance in 92.5% GVL yield under mild conditions. With the combination of detail catalyst characterizations, catalytic performance of the Zr-LigS catalyst, in-situ ATR-FTIR and poisoning experiments, the hydrothermal treatment of Zr4+ and LigS resulted in the formation of basic sites, which contributed significantly to the CTH reaction. Kinetic experiments demonstrated that the activation energy was as low as 41.9 kJ/mol. Furthermore, isotopic labeling experiments suggested that the β-H in isopropanol is transferred to the CO bond of LA by the formation of six-membered intermediates on the basic sites, which is the rate-determining step.

Catalytic transfer hydrogenation of levulinic acid to γ-valerolactone over an acids-base trifunctional Hf-bagasse coordination complex derived catalyst

Both value-added utilization of agricultural waste to prepare catalytic materials and selective conversion of biomass-based carbonyl compounds are hot topics. Herein, sugarcane bagasse (SB), a main by-product of cane sugar manufacturing industry, was directly assembled with HfCl4 and methanesulfonic acid (MSA) via a one-step hydrothermal method for scalable preparation of Hf-containing coordination complex (Hf@SB-MSA). Characterization results revealed that the coordination between Hf4+ and phenolic hydroxyl, alcohol hydroxyl, carboxyl groups in SB resulting in the formation of Lewis acid (LA) and Lewis base (LB) sites, while sulfonic group in MSA providing Brønsted acid (BA) sites. The cooperative role of LA, BA and LB in Hf@SB-MSA delivered prominent catalytic performance for catalytic transfer hydrogenation (CTH) of levulinic acid (LvA) to γ-valerolactone (GVL) with isopropanol as solvent and H-donor at mild reaction conditions (GVL yield was up to 99.1%). Heterogeneity and recycling experiments further revealed the good recyclability of Hf@SB-MSA, which can be easily separated from the reaction mixture by filtration and repetitively used at least five reaction runs without an obvious loss of activity. More gratifyingly, Hf@SB-MSA also displayed superior universality for the CTH of various carbonyl compounds to their corresponding alcohols with yields up to 90%.

Zirconium-Gallic Acid Coordination Polymer: Catalytic Transfer Hydrogenation of Levulinic Acid and Its Esters into γ-Valerolactone

Zirconium-Gallic Acid Coordination Polymer: Catalytic Transfer Hydrogenation of Levulinic Acid and Its Esters into γ-Valerolactone

Versatile functionalized mesoporous Zr/SBA-15 for catalytic transfer hydrogenation and oxidation reactions

Through this work, a family of sulfonamide functionalized mesoporous materials as sustainable heterogeneous catalysts has been successfully synthesized by employing sulfaguanidine, sulfathiazole, and sulfadiazine. The samples were fully characterized using a multitechnique approach. Such materials have proved to be highly versatile and catalytically active in both the advances in the hydrogenation of Levulinic acid through heterogeneous catalytic transfer hydrogenation (CTH) and oxidation reactions with a strong emphasis on discussing morphology and structure of versatile catalysts, plausible mechanism, and performance of the catalysts for biomass valorization of renewable feedstock. In particular, the prepared catalytic systems were tested in levulinic acid transformation into γ-Valerolactone, achieving a maximum conversion of 99% and a selectivity of 90% for the sulfaguanidine modified sample. The three nanocatalysts displayed good stability over four reuse cycles, and by considering the results of a hot filtration test, it is confirmed that the nature of the catalysis is heterogeneous as acid-base pairs and functionalized groups on catalytic activation of C–H and CO bonds for transfer hydrogenation of levulinic acid. Moreover, such samples also showed remarkable results in the oxidation of benzyl alcohol towards benzaldehyde, with conversion and selectivity values of 95% and 97%, respectively. The obtained catalytic results are highly promising for biomass upgrading processes, looking forward to a more sustainable future.

Highly efficient g-C3N4 supported ruthenium catalysts for the catalytic transfer hydrogenation of levulinic acid to liquid fuel γ-valerolactone

Gamma-valerolactone (GVL) is a versatile building block compound with wide applications and it can be obtained from biomass-derived chemical levulinic acid (LA). In this study, graphite carbon nitride (g-C3N4) were prepared from two different precursors (urea and melamine) and used as the support to anchor ruthenium (Ru) nanoparticle (Ru/g-C3N4) for catalytic transfer hydrogenation of LA to GVL. The resulting catalyst prepared from urea precursor (Ru/UCN) showed 100% LA conversion and nearly theoretic GVL yield of 99.8% under mild condition. Detailed characterizations of the Ru/g-C3N4 suggested that Ru showed different interactions with the g-C3N4 supports from two different precursors. Ru nanoparticles exhibited smaller size and better dispersion on the g-C3N4 support from urea (UCN) than that from melamine (MCN). The XPS result indicated that more electron rich Ru0 species on the Ru/UCN catalyst also contributed to the higher catalytic activity of the Ru/UCN. Furthermore, the Ru/UCN catalyst was demonstrated high stability in acidic reaction medium and remained highly reactive after recycled for 5 times.

Ir(triscarbene)‐catalyzed sustainable transfer hydrogenation of levulinic acid to γ‐valerolactone

Sustainable iridium‐catalyzed transfer hydrogenation using glycerol as the hydride source was employed to convert levulinic acid to γ‐valerolactone (GVL) with exceptionally high turnover numbers (TONs) (500,000) and turnover frequencies (TOFs) (170,000 h−1). The highly efficient triscarbene‐modified iridium catalysts demonstrated good catalytic activities with low catalyst loadings (0.7 ppm) and good recyclability with an accumulated TON of over two million in the fourth reaction. In addition to glycerol, propylene glycol (PG), ethylene glycol (EG), isopropanol (IPA), and ethanol (EtOH) successfully transferred hydrides to levulinic acid, producing GVL with TONs of 339,000 (PG), 242,000 (EG), 334,000 (IPA), and 208,000 (EtOH), respectively. Deuterium‐labeling experiments were conducted to gain insight into the reaction mechanism.

A comparative study on microwave-assisted catalytic transfer hydrogenation of levulinic acid to γ-valerolactone using Ru/C, Pt/C, and Pd/C

Conversion of levulinic acid (LA) to γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) using conventional heating (CH) involves long reaction times, and low yields. Microwave (MW) heating seems a solution to address these issues as MW accelerates reactions and enhances yields. In this study, three typical catalysts, Ru/C, Pt/C and Pd/C, are compared for LA conversion using MW heating. In comparison to CH processes, MW-assisted processes significantly enhance LA conversion to GVL with higher yields by Ru/C and Pt/C. While elevated temperatures and secondary alcohols are favorable for LA conversion by these catalysts, Ru/C appears as the most effective catalyst as it can reach LA conversion as 100%, selectivity of GVL as 99% and yield of GVL as 99% at 160 °C. The results of this study confirm that MW was a promising process for enhancing LA conversion and Ru/C shows the highest catalytic activity, followed by Pt/C and Pd/C.

Transfer hydrogenation of levulinic acid from glycerol and ethanol using water-soluble iridium N-heterocyclic carbene complexes

The upgrading of biomass derivatives to biofuels and chemicals through transfer hydrogenation (TH) is attractive relative to direct hydrogenation, especially when the hydrogen donors can be sourced renewably. Here we report the first process that uses glycerol, a renewable waste material from biodiesel processing, as a hydrogen donor in the catalytic TH of a biomass-derived platform chemical, levulinic acid, to selectively afford γ-hydroxyvaleric acid (GHV) and lactic acid (LA). GHV can be further converted to γ-valerolactone (GVL), a widely used platform chemical. Levulinic acid can be used directly, without esterification, which is typically needed for transfer hydrogenation. The process is efficiently facilitated by robust iridium N-heterocyclic carbene (NHC) complexes with sulfonate functional groups at low catalyst loading (1–10 ppm), affording quantitative conversion of levulinic acid in the presence of KOH to GHV, with >100,000 TON in 2 h at 150 °C, using 1 ppm catalyst. The most prolific catalyst, [(NHC-SO3-)2(CO)2Ir]Na, can also facilitate transfer hydrogenation from other hydrogen donors, such as 2-propanol, potassium formate, and most notably, ethanol, which can also be derived from renewables. Ethanol is a highly efficient hydrogen donor for levulinic acid using this catalyst, affording >7,000 turnovers in 2 h using 10 ppm catalyst.

Lattice distorted MnCo oxide materials as efficient catalysts for transfer hydrogenation of levulinic acid using formic acid as H-donor

Catalytic transfer hydrogenation of levulinic acid using H-donors represents one of the most promising routes to replace conventional hydrogenation processes using fossil-derived H2. Current studies on catalyst design are focused on the effects of metal composition and metal-support interaction on tandem H2 generation and hydrogenation. However, the influence of lattice-mismatch induced structural distortion on catalytic CH and CO bond cleavage is largely unexplored in this area. We proposed unique MnCo-based oxide catalysts for transfer hydrogenation of levulinic acid to γ-valerolactone using formic acid as H-donor. The key finding is that, lattice distortion of MnCo oxides induces electronically coupled MnCoO3 phase at MnOx-CoOx interface as intrinsically active site for transfer hydrogenation. Catalyst characterization by XRD, XPS, and TEM techniques were interpreted to further demonstrate the synergism of MnCo-based catalysts for tandem hydrogenation reactions. This work will provide insights into the development of structurally distorted inexpensive metal oxide catalysts for transfer hydrogenation technologies.

Efficient transfer hydrogenation of biomass derived furfural and levulinic acid via magnetic zirconium nanoparticles: Experimental and kinetic study

A series of magnetic zirconium nanoparticles with varied Zr/Fe molar ratios were synthesized and developed as acid−base bifunctional catalysts in the catalytic transfer hydrogenation (CTH) of biomass-derived furfural (FFR) and levulinic acid (LA) using 2-propanol as both hydrogen donor and solvent. Zirconium constituents coated on nano-sized Fe3O4 endowed the catalysts with abundant acid−base sites, moderate surface areas (94.0‒187.6 m2/g) and pore sizes (3.42–9.51 nm), thus giving nearly 100 % yields of furfuryl alcohol (FA) and γ-valerolactone (GVL) after 2 h of reaction. Particularly, competitive activation energy (Ea) for the CTH of FFR into FA over Zr1Fe1-300 was as low as 50.9 kJ/mol. Moreover, the easily separable nanocatalyst Zr1Fe1-150 was also applicable to CTH of various alkyl levulinates into GVL in high efficiency and could be reused for multiple cycles without obvious loss of its catalytic performance in the transfer hydrogenation of LA.

Valorization of Carbohydrates of Agricultural Residues and Food Wastes: A Key Strategy for Carbon Conservation

The complete conservation of the carbon, hydrogen, and oxygen atoms of cellulose and starch can theoretically be achieved by their conversion to levulinic and formic acids. Similarly, hemicellulose can be converted to furfural and water with 100% atom economy. The valorization of carbohydrates of agricultural residues (banana-, orange-, and potato-peels, corn leaf and root, and rice husk), potential components of raw food wastes (corn, rice, potato, lettuce, onion, leek, vegetable, bean, and tomato), and cooked food wastes (rice noodle, spaghetti, risotto, noodle, bread, and biscuit) was demonstrated in the presence of sulfuric acid at 130 °C in γ-valerolactone as the green solvent to yield levulinic and formic acids as the two main products. Levulinic acid was also produced from furfural by its transfer hydrogenation with formic acid to furfuryl alcohol in the presence of Shvo’s catalyst followed by its acid catalyzed conversion to levulinic acid. Neutralization of the sulfuric acid in the reaction mixture with ammonium hydroxide resulted in an aqueous ammonium sulfate phase and a γ-valerolactone rich organic phase. Due to the salting out effect of the ammonium sulfate in the aqueous phase, levulinic acid and formic acid partitioned to the γ-valerolactone rich organic phase at >99.8% and >97.1%, respectively. The transfer hydrogenation of levulinic acid with formic acid in the presence of the Shvo’s catalyst resulted in the formation of 4-hydroxyvaleric acid, which readily underwent dehydration to yield γ-valerolactone, a green and sustainable liquid. The possibility of converting C₅- and C₆-carbohydrates to levulinic acid or γ-valerolactone is a great opportunity for carbon conservation with a carbon-economy higher than that for butanol or ethanol.

Microwave Irradiation-Enhanced Catalytic Transfer Hydrogenation of Levulinic Acid to γ-Valerolactone Using Ruthenium: A Comparative Study with Conventional Heating Processes

Conversion of biomass-derived levulinic acid to γ-valerolactone (GVL) via catalytic transfer hydrogenation (CTH) using conventional oven heating (COH) is associated with issues, such as long reaction time, and low yield. Microwave irradiation (MWI) appears to be a solution to address these issues as MWI can shorten reaction times and enhance yields. To explore effectiveness of MWI for LA conversion, MWI and COH are compared for LA conversion via CTH catalyzed by a model catalyst, Ru/C. Through investigating the effects of temperature and reaction time, MWI is validated to shorten the reaction time and enhance LA conversion efficiencies in comparison with COH. The optimal condition for the full LA conversion to GVL by Ru/C using MWI is 160 °C for 30 min with 10 mg (Ru/C)/mL (2-PrOH). MWI is also validated to improve conversion of several common levulinate esters (LAEs) to GVL. The regenerated Ru/C can also exhibit almost the same catalytic activity as the pristine Ru/C for LA conversion using MWI. These results indicate that Ru/C is a highly-effective catalyst for LA conversion and MWI can further enhance LA conversion by Ru/C by shortening reaction time and increasing yield of GVL. Thus, MWI is a promising process for enhancing biomass conversion.

Water-born zirconium-based metal organic frameworks as green and effective catalysts for catalytic transfer hydrogenation of levulinic acid to γ-valerolactone: Critical roles of modulators

While zirconium (Zr)-based metal organic frameworks (MOFs) are promising for conversion of levulinic acid (LA) to γ-valerolactone (GVL) through catalytic transform hydrogenation (CTH), these reported Zr MOFs for LA conversion must be synthesized in toxic dimethylformamide (DMF). From the viewpoint of sustainability, it is preferable to avoid usage of DMF-based solvents to prepare these Zr MOFs. As water is a green solvent, the aim of this study is to develop and investigate Zr MOFs, which are prepared in water, for LA conversion to GVL. Specifically, monocarboxylic acids (e.g., formic acid, acetic acid and propanoic acid) are employed as modulators during the preparation of water-born ZrF. The role of modulators is extremely important for the well-developed formation of water-born ZrF. In addition, different monocarboxylic acid modulators also significantly influence the morphology of water-born ZrF; nevertheless, their crystalline structures and acidities are equivalent. As for LA conversion, these water-born modulated ZrF MOFs are validated to successfully convert LA to GVL. Especially, the formic acid-modulated ZrF can exhibit LA conversion = 96%, selectivity for GVL = 98% and yield of GVL = 98%. These water-born modulated ZrF also exhibit even higher catalytic activities than the typical DMF-based ZrF and reported Zr-based MOFs in LA conversion to GVL. These water-born ZrF could be also reused even without regeneration for multiple cyclic LA conversion. These results and findings prove that the water-born ZrF is not only environmentally benign but also more effective for LA conversion to GVL.