Hydrogenation Of Levulinic Acid Research Articles

Efficient hydrogenation of levulinic acid catalysed by spherical NHC-Ir assemblies with atmospheric pressure of hydrogen

Enhanced catalytic activity towards hydrogenation of levulinic acid to γ-valerolactone under 1 atm H2 was realized by spherical porous self-supported NHC-Ir catalysts.

The transfer hydrogenation of high concentration levulinic acid to γ-valerolactone catalyzed by glucose phosphate carbamide zirconium

Newly constructed glucose phosphate carbamide zirconium (GluPC-Zr) is an inexpensive, excellent, and recyclable CTH catalyst for the synthesis of γ-valerolactone (γ-GVL) using high concentrations of levulinic acid (LA ).

Choline chloride-promoted efficient solvent-free hydrogenation of biomass-derived levulinic acid to γ-valerolactone over Ru/C

The hydrogen bond between LA and ChCl boosted the solvent-free hydrogenation of LA over Ru/C by alleviating the adsorption of the carboxylic group and enhancing the adsorption of the acyl group of LA.

Efficient Transfer Hydrogenation of Alkyl Levulinates and Levulinic Acid to γ‑Valerolactone Over Mesoporous Reduced Cuo Catalyst

Efficient Transfer Hydrogenation of Alkyl Levulinates and Levulinic Acid to γ‑Valerolactone Over Mesoporous Reduced Cuo Catalyst

A nitrogen-doped carbon modified nickel catalyst for the hydrogenation of levulinic acid under mild conditions

A nitrogen-doped carbon modified nickel catalyst was used for the hydrogenation of levulinic acid to γ-valerolactone under ambient hydrogen pressure. The catalyst showed excellent activity in various solvents and could be recycled for at least six runs.

Improving the hydrothermal stability of zeolite Y by La3+ cation exchange as a catalyst for the aqueous-phase hydrogenation of levulinic acid.

La3+ cation exchange is shown to improve the hydrothermal stability and catalytic activity of bifunctional zeolite Pt/Y catalysts in the aqueous-phase hydrogenation of levulinic acid (LA) with formic acid (FA) as hydrogen source. La3+ cation exchange of zeolite Y (nSi/nAl = 16) was conducted both in aqueous solution and in the solid state. The hydrothermal stability of La3+-containing zeolite Y probed by exposure to the reaction mixture (0.2 mol L−1 LA, 0.6 mol L−1 FA) at 473 K under autogenous pressure for 24 h improves with increasing La content. The material exhibiting the highest La content (0.5 mmol g−1) is the most stable with a preservation of 25% of the initial specific micropore volume after the hydrothermal treatment, whereas unmodified zeolite Y completely loses its microporosity. A new procedure using DRIFTS is a useful supplementary tool for quantifying the framework degradation of Y-type zeolites after hydrothermal treatment. Bifunctional Pt/Y catalysts after La3+ cation exchange are more active than the parent Y-zeolite for the hydrogenation of LA to γ-valerolactone (GVL), with significant enhancements in LA conversion, i.e., 94% vs. 42%, and GVL yield, i.e., 72% vs. 34%., after 24 h.

Levulinic acid hydrogenation to γ-valerolactone over single Ru atoms on a TiO2@nitrogen doped carbon support

TiO2@nitrogen doped porous carbon dispersed single Ru atom catalyst (Ru/TiO2@CN) efficiently transforms levulinic acid into γ-valerolactone at room temperature in water with a turnover frequency of 278 molGVL molRu−1 h−1 at complete conversion.

Mono- and bimetallic (Ru-Co) polymeric catalysts for levulinic acid hydrogenation

Levulinic acid (LA) is one of the substances, which can be obtained from cellulosic biomass via acid hydrolysis and serves as a precursor in the synthesis of gamma-valerolactone (GVL) – platform chemical for so-called valeric fuels. This work is devoted to the study of catalytic conversion of LA to GVL using mono- (Ru) and bimetallic (Ru-Co) catalysts based on ruthenium-containing nanoparticles immobilized in hyper-crosslinked polystyrene (HPS). It was shown that RuO2 nanoparticles are an active phase of HPS-based Ru catalysts, which allow nearly 100 % yield of GVL at 120 °C and 2 MPa of hydrogen partial pressure for the reaction time 60 min. Introduction of cobalt in catalyst composition in a proper amount (Ru-to-Co weight ratio is 30) was found to result in Ru redistribution inside the polymeric support and, in turn, to the increase of reaction rate of LA hydrogenation.

Synthesis and characterisation of a range of Fe, Co, Ru and Rh triphos complexes and investigations into the catalytic hydrogenation of levulinic acid

The coordination chemistry of the N-triphos ligand (NP3Ph, 1b) has been investigated with a range of Fe, Co and Rh precursors and found to form either tridentate or bidentate complexes. Reaction of NP3Ph with [Rh(COD)(CH3CN)2]BF4 resulted in the formation of the tridentate complex [Rh(COD)(κ3-NP3Ph)]BF4 (3) in the solid state, however, in solution a bidentate complex predominates in more polar solvents. Reaction of NP3Ph with Fe carbonyl precursors revealed the formation of the bidentate complexes [Fe(CO)3(κ1,κ2-NP3Ph)Fe(CO)4] (4) and [Fe(CO)3(κ2-NP3Ph)] (5), while reaction with FeBr2 resulted in the paramagnetic bidentate complex [Fe(Br)2(κ2-NP3Ph)] (6). Reaction of NP3Ph with CoCl2 gave a dimeric Co species [(κ2-NP3Ph)CoCl(κ1,κ2-NP3Ph)CoCl3] (7), while Zn powder reduction of NP3Ph Co halides resulted in the formation of the tridentate complexes of the type: [Co(X)(κ3-NP3Ph)]. The related triphos Ru complex, [Ru(CO3)(CO)(κ3-CP3Ph)] (2), has also been isolated and characterised. Preliminary catalytic hydrogenation of levulinic acid (LA) was conducted with 2 and 3. The Ru complex was found to be catalytically active, giving high conversions of LA to form gamma-vvvalerolactone (GVL) and 1,4-pentanediol (1,4-PDO), while 3 was found to be catalytically inactive. In situ catalytic testing with 1b and Fe(BF4)2.6H2O resulted in low conversions of LA while a combination of 1b and Co(BF4)2.6H2O gave high conversions to GVL.

Selective hydrogenation of levulinic acid to γ-valerolactone using bimetallic Pd-Fe catalyst supported on titanium oxide

The synthesis of γ-valerolactone (GVL), a versatile precursor in the manufacture of high-value chemicals such as polymer plasticizer, solvent, jet fuel, and, agrochemicals, has been targeted by many research groups. In this study, we report the catalytic performance of iron-modified palladium supported on titanium oxide (denoted as Pd(5.0)-Fe(5.0)/TiO2; 5.0 was the loading amount of Pd and Fe, respectively) in the selective hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) in stainless-steel batch reactor system. Pd(5.0)-Fe(5.0)/TiO2 catalyst was synthesized by a simple hydrothermal method at 150°C for 24 h, then followed by reduction with H2 at 500°C for 3 h. The X-ray diffraction (XRD) patterns of Pd(5.0)-Fe(5.0)/TiO2 before and after reduction showed the formation of metallic Pd at 2θ = 40.34° and 47.2° corresponding to Pd(111) and Pd(200), respectively. The hydrogenation of LA to GVL effectively occurred in the H2O solvent, whereas in 2-propanol the formation of ester was the main side product. The highest yield of GVL (52.5%) was obtained over Pd(5.0)-Fe(5.0)/TiO2 catalyst at a temperature of 170 °C, initial H2 pressure of 4.0 MPa, solvent H2O 3 ml at a reaction time of 7 h. The yield of GVL slightly increased to 63.3% when the reaction time was prolonged to 15 h.

NNN Pincer‐functionalized Porous Organic Polymer Supported Ru(III) as a Heterogeneous Catalyst for Levulinic Acid Hydrogenation to γ‐Valerolactone

AbstractA novel porous organic polymer that incorporates NNN pincer type of ligand, i. e., 2,6‐Bis(pyrazol‐3‐yl)pyridine, (3‐bpp‐POP) is prepared via solvent‐knitting method. Through the characterizations, 3‐bpp‐POP is demonstrated to possess abundant porous structure, high surface area, and excellent thermal durability. A ruthenium molecular catalyst immobilized on the 3‐bpp‐POP support exhibits substantial catalytic performance for the hydrogenation of LA to GVL with an initial turnover frequency (TOF) of 1680 h−1 and a maximum turnover number (TON) of 14762 over 24 h for LA conversion with selectivities of 91.1 % for GVL and 8.9 % for HPA. The catalyst demonstrated excellent durability during successive recycles without leaching Ru3+, which ascribe to the strong binding of pincer ligand to metal centers.

Hydrophobic Copper Catalysts Derived from Copper Phyllosilicates in the Hydrogenation of Levulinic Acid to γ-Valerolactone.

A reduction-silylation-reduction method was developed to synthesize hydrophobic Cu catalysts derived from Cu phyllosilicates (CuPS). Triethoxy(octyl)silane (OTS) was used as the coupling agent. The OTS-grafted, reduced CuPS catalysts were applied in the hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The most promising catalyst was synthesized by reducing CuPS at a high temperature (350 °C for 3 h), followed by OTS grafting, and then by repeating the previous reduction step. High LA conversion (95.7%), GVL yield (85.2%), and stability (3 cycles with a 7.5% loss of initial activity) were obtained at a mild reaction condition (130 °C with a H2 pressure of 12 bar). A high reduction temperature not only leads to a low oxidation state of Cu species but also suppresses the formation of silylation-induced acids. Moreover, the intrinsic activity of a reduced CuPS catalyst was nearly intact after subjecting to silylation and the second reduction treatment.

Supported Bimetallic Catalysts for the Solvent-Free Hydrogenation of Levulinic Acid to γ-Valerolactone: Effect of Metal Combination (Ni-Cu, Ni-Co, Cu-Co)

γ-valerolactone (GVL) is an important value-added chemical with potential applications as a fuel additive, a precursor for valuable chemicals, and polymer synthesis. Herein, different monometallic and bimetallic catalysts supported on γ-Al2O3 nanofibers (Ni, Cu, Co, Ni-Cu, Ni-Co, Cu-Co) were prepared by the incipient wetness impregnation method and employed in the solvent-free hydrogenation of levulinic acid (LA) to GVL. The influence of metal loading, metal combination, and ratio on the activity and selectivity of the catalysts was investigated. XRD, SEM-EDS, TEM, H2-TPR, XPS, NH3-TPD, and N2 adsorption were used to examine the structure and properties of the catalysts. In this study, GVL synthesis involves the single-step dehydration of LA to an intermediate, followed by hydrogenation of the intermediate to GVL. Ni-based catalysts were found to be highly active for the reaction. [2:1] Ni-Cu/Al2O3 catalyst showed 100.0% conversion of LA with >99.0% selectivity to GVL, whereas [2:1] Ni-Co/Al2O3 yielded 100.0% conversion of LA with 83.0% selectivity to GVL. Moreover, reaction parameters such as temperature, H2 pressure, time, and catalyst loading were optimized to obtain the maximum GVL yield. The solvent-free hydrogenation process described in this study propels the future industrial production of GVL from LA.

Highly active and stable Co nanoparticles embedded in nitrogen-doped mesoporous carbon nanofibers for aqueous-phase levulinic acid hydrogenation

Developing a highly active and durable non-noble metal catalyst for aqueous-phase levulinic acid (LA) hydrogenation to γ-valerolactone (GVL) is an appealing yet challenging task. Herein, we report well-dispersed Co nanoparticles (NPs) embedded in nitrogen-doped mesoporous carbon nanofibers as an efficient catalyst for aqueous-phase LA hydrogenation to GVL. The Co zeolitic imidazolate framework (ZIF-67) nanocrystals were anchored on the sodium dodecyl sulfate modified wipe fiber (WF-S), yielding one-dimensional (1-D) structured composite (ZIF-67/WF-S). Subsequently, Co NPs were uniformly embedded in nitrogen-doped mesoporous carbon nanofibers (CoRNC/SMCNF) through a pyrolysis-reduction strategy using ZIF-67/WF-S as the precursor. Benefiting from introducing modified wipe fiber WF-S to enhance the dispersion of Co NPs, and Co0 with Co-Nx dual active sites, the resulting CoRNC/SMCNF catalyst shows brilliant catalytic activity (206 h−1 turnover frequency). Additionally, the strong metal–support interactions greatly inhibited the Co NPs from aggregation and leaching from the mesoporous carbon nanofibers, and thus increasing the reusability of the CoRNC/SMCNF catalyst (reusable nine times without notable activity loss).

The Influence of Carbon Nature on the Catalytic Performance of Ru/C in Levulinic Acid Hydrogenation with Internal Hydrogen Source.

The influence of the nature of carbon materials used as a support for Ru/C catalysts on levulinic acid hydrogenation with formic acid as a hydrogen source toward gamma-valerolactone was investigated. It has been shown that the physicochemical properties of carbon strongly affect the catalytic activity of Ru catalysts. The relationship between the hydrogen mobility, strength of hydrogen adsorption, and catalytic performance was established. The catalyst possessing the highest number of defects, stimulating metal support interaction, exhibited the highest activity. The effect of the catalyst grain size was also studied. It was shown that the decrease in the grain size resulted in the formation of smaller Ru crystallites on the catalyst surface, which facilitates the activity.

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.

Enhanced activity of Ru-Ir nanoparticles over SiC for hydrogenation of levulinic acid at room-temperature

The hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL) under mild condition is a promising but challenging process. Herein, SiC supported Ru-Ir bimetallic catalyst exhibit enhanced catalytic activity for aqueous hydrogenation of LA into GVL under mild conditions. Comparing with monometallic Ir3/SiC and Ru3/SiC, the conversion of LA over bimetallic Ru0.5-Ir2.5/SiC catalyst increase from 51.2 % and 45.9% to 100% at 25 °C and 0.2 MPa of H2 pressure. The enhanced catalytic activity of Ru0.5-Ir2.5/SiC catalyst originates from the electronic synergistic effect among Ru, Ir and SiC. Due to the electron transfer, electron-richened Ir nanoparticles show stronger ability for H2 dissociation, and the SiC surface produces more active sites to accommodate hydrogen species that spill over from Ir and Ru. The adsorption and hydrogenation of LA molecules occur on the surface of SiC.

Recent advances in the production of γ-valerolactone with liquid hydrogen source

Gamma(γ)-valerolactone (GVL) which can be produced from carbohydrate biomass has been regarded as one of the most promising platform chemicals because it can be converted to liquid alkenes adapted for transportation fuels. In the producing process, GVL was synthesized via hydrogenation of levulinic acid, which was obtained from acidic hydrolysis of carbohydrate biomass. Generally, gaseous hydrogen was employed as hydrogen source in the hydrogenation reaction. However, highly pure and high-pressure gaseous hydrogen faces high risk of hydrogen storage, transportation and operation. Moreover, due to the need for activating the gaseous hydrogen, noble metal catalysts were commonly used, limited the large-scale application. Some liquids, such as formic acid, alcohol and water, can act as hydrogen donor under cerain conditions. Liquid hydrogen source possesses safe and high efficiency advantages in the hydrogenation process. This paper highlights the recent progress in the production of GVL with liquid hydrogen source.

High-Temperature Synthesis of Small-Sized Pt/Nb Alloy Catalysts on Carbon Supports for Hydrothermal Reactions.

Catalytic biomass conversions are sustainable processes to produce value-added fuels and chemicals but need stable catalysts that can tolerate harsh hydrothermal conditions. Herein, we report a hydrothermally stable catalyst by alloying Pt with a high-melting-point metal Nb. The Pt/Nb alloy catalysts are prepared by H2 reduction at a high temperature of 900 °C with a high-surface-area carbon black support, which can suppress metal sintering at high temperatures and thus lead to small-sized alloyed Pt/Nb particles of only 2.2 nm. Taking the advantages of surface acid property provided by the Nb sites and the size effect, the prepared C-supported small-sized Pt/Nb alloy catalysts exhibit attractive activities for the hydrogenation of levulinic acid into γ-valerolactone and the water-gas shift reaction. More significantly, benefiting from the inherent stability of high-melting-point Nb, the Pt/Nb alloy catalysts show much enhanced hydrothermal stability compared to commercial Pt/C and Ru/C catalysts.

Heterogeneously Catalyzed γ-Valerolactone Hydrogenation into 1,4-Pentanediol in Milder Reaction Conditions

Hydrogenation of γ-valerolactone (GVL) in polar solvents (n-butanol, 1,4-dioxane) to 1,4-pentanediol (PDO) and 2-methyltetrahydrofuran (MTHF) was performed at 363–443 K in a fixed bed reactor under overall H2 pressure of 0.7–1.3 MPa. Preliminary screening in a batch reactior was performed with a series of Ru, Ir, Pt, Co, and Cu catalysts, earlier efficiently applied for levulinic acid hydrogenation to GVL. The fresh catalysts were analyzed by transmission electron microscopy (TEM), X-ray fluorescent analysis (XRF), temperature programmed reduction by H2 (H2-TPR), and N2 physisorption. Cu/SiO2 prepared by reduction of copper hydroxosilicate with chrysocolla mineral structure provided better selectivity of 67% towards PDO at 32% GVL conversion in a continuous flow reactor. This catalyst was applied to study the effect of temperature, hydrogen pressure, and contact time. The main reaction products were PDO, MTHF, and traces of pentanol, while no valeric acid was observed. Activity and selectivity to PDO over Cu/SiO2 did not change over 9 h, indicating a fair resistance of copper to leaching.