Biomass-derived Levulinic Acid Research Articles

Synthesis and Characterization of Zirconia Supported Silicotungstic Acid for Ethyl Levulinate Production

A Keggin silicotungstic acid (HPS) catalyst was heterogenized by loading (10–40 wt %) over zirconia support, and the resulting catalysts were named ESZN-1 (10 wt %), ESZN-2 (20 wt %), ESZN-3 (30 wt %), and ESZN-4 (40 wt %). After that, synthesized catalysts were characterized using several tools and techniques which revealed that the Keggin structure of the parent HPS catalyst remained intact after heterogenization. Eventually, synthesized catalyst performance evaluation tests were performed for the production of ethyl levulinate from biomass-derived levulinic acid under microwave heating irradiations. Under optimum operating conditions, more than 90% LA conversion with 100% EL selectivity was obtained at a 110 °C temperature in 30 min in the presence of 100 mg of ESZN-4 in a solution containing levulinic acid and ethanol in a 1:43 ratio. A kinetic study on LA conversion in the presence of the ESZN-4 catalyst revealed a pseudo-first-order mechanism for ethyl levulinate synthesis.

Production of levulinic acid and ethyl levulinate from cellulosic pulp derived from the cooking of lignocellulosic biomass with active oxygen and solid alkali

Biomass-derived levulinic acid (LA) and its esters are currently envisaged as versatile, renewable platform chemicals. In this study, cellulosic pulp derived from the cooking of lignocellulosic biomass with active oxygen and solid alkali was employed as raw material for the formation of LA or ethyl levulinate (EL). This pretreatment process is highly effective for the delignification and deconstruction of lignocellulose matrix, making a facile degradation of the resulting cellulosic pulp to LA or EL. At this point, the acid-catalyzed hydrolysis or ethanolysis of cellulosic pulp was optimized by response surface methodology (RSM), offering desirable LA yield of 65.3% or EL yield of 62.7%, which is significantly higher than those obtained from raw biomass. More importantly, coking behavior on the inwall of the reactor was eliminated during the hydrolysis or ethanolysis of cellulosic pulp, which is one of the top challenges for the acid-catalyzed conversion of biomass in an industrial scale.

Green synthesis of gamma-valerolactone (GVL) through hydrogenation of biomass-derived levulinic acid using non-noble metal catalysts: A critical review

The distinct physicochemical properties and renewable origin of gamma-valerolactone (GVL) have provided opportunities for diversifying its applications, particularly as a green solvent, excellent fuel additive, and precursor to valuable chemicals. Among the related publications found in the SCOPUS database (≈172 in the last 10 years), we focused our effort to review the conversion of levulinic acid (LA) to GVL over non-noble metal catalysts and the corresponding mechanisms (≈30 publications) as well as the applications of GVL as a solvent, fuel additive, and platform chemical (≈30 publications) mostly in the last five years (some preceding publications have also been included due to their relevance and importance in the field). The use of non-noble metals (e.g., Cu and Zr) presents a greener route of GVL synthesis than the conventional practice employing noble metals (e.g., Pd and Ru), in view of their higher abundance and milder reaction conditions needed (e.g., low pressure and temperature without H2 involved). The significance of the catalyst characteristics in promoting catalytic transfer hydrogenation of LA to GVL is critically discussed. Structural features and acid-base properties are found to influence the activity and selectivity of catalysts. Furthermore, metal leaching in the presence of water in catalytic systems is an important issue, resulting in catalyst deactivation. Various endeavors for developing catalysts using well-dispersed metal particles along with a combination of Lewis acid and base sites are suggested for efficiently synthesizing GVL from LA.

Production of n-butyl levulinate over modified KIT-6 catalysts: comparison of the activity of KIT-SO3H and Al-KIT-6 catalysts

The catalytic activity of propylsulfonic acid-functionalized mesoporous silica (KIT-SO3H) was compared to the performance of alumina-incorporated KIT-6 (Al-KIT-6) in the esterification reaction of the biomass-derived levulinic acid with n-butanol. The catalysts were prepared by functionalization of the silica support with propylsulfonic acid (Pr-SO3H) by post-synthesis grafting using 3-mercaptopropyltrimethoxysilane as a propyl-thiol precursor followed by oxidation. In addition, Al-KIT-6 was synthesized according to in situ synthesis. Catalysts were characterized using various techniques such as XRD, nitrogen adsorption/desorption, SEM, TGA, ICP-OES, FT-IR and elemental analysis. It is evident that increases in catalyst loading, butyl alcohol-to-levulinic acid ratio and reaction temperature significantly enhance the butyl levulinate yield. The reusability and stability of catalysts were evaluated, and it was found that while esterification reaction by KIT-SO3H compound catalyzed under milder conditions, the stability of Al-KIT-6 catalyst was better.

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.

Ambient Reductive Amination of Levulinic Acid to Pyrrolidones over Pt Nanocatalysts on Porous TiO2 Nanosheets.

Construction of N-substituted pyrrolidones from biomass-derived levulinic acid (LA) via reductive amination is a highly attractive route for biomass valorization. However, realizing this transformation using H2 as the hydrogen source under mild conditions is still very challenging. Herein, we designed porous TiO2 nanosheets-supported Pt nanoparticles (Pt/P-TiO2) as the heterogeneous catalyst. The prepared Pt/P-TiO2 was highly efficient for reductive amination of LA to produce various N-substituted pyrrolidones (34 examples) at ambient temperature and H2 pressure. Meanwhile, Pt/P-TiO2 showed good applicability for reductive amination of levulinic esters, 4-acetylbutyric acid, 2-acetylbenzoic acid, and 2-carboxybenzaldehyde. Systematic studies indicated that the strong acidity of P-TiO2 and the lower electron density of the Pt sites as well as the porous structure resulted in the excellent activity of Pt/P-TiO2.

Selective conversion of biomass-derived levulinic acid to ethyl levulinate catalyzed by metal organic framework (MOF)-supported polyoxometalates

The esterification of levulinic acid (LA) and ethanol into ethyl levulinate is an attractive biomass conversion process since the product EL has wide applications as food additive, fragrance and fuel. Herein, a metal-organic framework (MOF)-supported phosphomolybdic acid [Cu-BTC][HPM] was synthesized with 1,3,5-Benzenetricarboxylic acid, copper nitrate and phosphomolybdic acid in a one-step process at ambient temperature. The synthesized [Cu-BTC][HPM] was used for the catalytic esterification of levulinic acid to EL in ethanol, and showed excellent activity with a high EL yield close to 100% at 120 °C for 6 h, which should be ascribed to the uniform dispersion of HPM embedded in the MOF. The [Cu-BTC][HPM] catalyst could keep stable crystal structure and active component contents, and thus exhibited good stability in recycling process.

Straightforward synthesis of calcium levulinate from biomass-derived levulinic acid and calcium carbonate in egg-shells

Abstract Calcium levulinate (CL) is a nutritional supplement for calcium and a chemical intermediate in synthesizing levulinic biofuels. The reported synthesis of CL involve reaction between cellulose-derived levulinic acid (LA) and calcium hydroxide in an aqueous medium. In this work, we report the production of CL using CaCO3 from poultry egg shells. The scalable production uses biomass-derived LA and egg-shell derived CaCO3 under conventional heating and mechanical stirring. The reaction was optimized on temperature, duration of reaction, and equivalent of CaCO3. Using 1.5 equivalent of CaCO3, the reaction completed within 2h at 50°C and afforded up to 97% isolated yield of CL as a crystalline solid. The reaction was also successfully carried out under mechanical grinding and scaled up to 20 g. The purity of the product was confirmed by melting point, FTIR, 1H-NMR and 13C-NMR spectroscopy.

Surface engineering in PbS via partial oxidation: towards an advanced electrocatalyst for reduction of levulinic acid to γ-valerolactone.

Development of mild and efficient strategies for biomass conversion is of great significance, and design of advanced catalysts is crucial for biomass valorization. Herein, we designed PbS-based electrocatalysts through a surface engineering strategy via partial oxidation, and the degree of surface oxidation of PbS to PbSO4 could be easily tuned by calcination temperature. It was discovered that the prepared electrocatalysts could efficiently catalyze reduction of biomass-derived levulinic acid (LA) to γ-valerolactone (GVL) using water as the hydrogen source. Especially, the electrocatalyst calcined at 400 °C (PbS-400) showed outstanding performance with a current density of 13.5 mA cm-2 and a GVL faradaic efficiency of 78.6%, which was far higher than the best results reported up to date. Moreover, GVL was the only product from LA reduction, indicating the excellent selectivity. Mechanism investigation showed that LA was converted through electrocatalytic hydrogenation of carbonyl groups of LA and subsequent intramolecular esterification.

Mixed-Ligand Ni(II), Co(II) and Fe(II) Complexes as Catalysts for Esterification of Biomass-Derived Levulinic Acid with Polyol and in Situ Reduction via Hydrogenation with NaBH4

Synthesizing polyol-based ester from biomass feedstocks for the preparation of biolubricant overcomes the dependence on petroleum oil usage. Albeit biomass-derived bio-oil is an alternative for the production of polyol ester, upgrading is essential prior to use as biolubricant. Levulinic acid (LA), obtained from bio-oil was applied for the catalytic esterification with two polyols, e.g., trimethylolpropane (TMP) and pentaerythritol (PE), in the presence of mixed-ligand Ni(II), Co(II), and Fe(II) complexes as catalyst. New mixed-ligand coordination complexes with empirical formula; [Ni(Phe)(Bpy)Cl].H2O, [Co(Phe)(Bpy)Cl].H2O, and [Fe(Phe)(Tyr)Cl].H2O were synthesized by the reaction of ligands [L-phenylalanine (Phe), 4,4'-bipyridine (Bpy), and L-tyrosine (Tyr)] with metal chloride salts and characterized by elemental analysis, magnetic susceptibility, FTIR, TGA/DTA, powder-XRD, and SEM techniques. This study aims to investigate the catalytic activities of the complexes via esterification reaction of levulinic acid with trimethylolpropane and pentaerythritol. In addition, these catalysts were further employed for the in situ hydrogenation of levulinate esters via NaBH4 at room temperature upon refluxing. Indeed, the iron(II) complex was more potential, exhibiting its efficiency as a homogeneous catalyst for esterification-hydrogenation reaction for synthesizing ester-based oils.

An efficient and reusable bimetallic Ni3Fe NPs@C catalyst for selective hydrogenation of biomass-derived levulinic acid to γ-valerolactone

Bimetallic nanostructures have attracted great interest as efficient catalyst to enhance activity, selectivity and stability in catalytical conversion. Herein, we report a facile one-pot carbothermal route to in-situ controllable synthesize heterogeneous bimetallic Ni3Fe NPs@C nanocatalyst. The X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and N2 adsorption-description results reveal that the Ni3Fe alloy nanoparticles are evenly embedded in carbon matrix. The as-prepared Ni3Fe NPs@C catalyst shows excellent selective hydrogenation catalytic performance toward the conversion of levulinic acid (LA) to γ-valerolactone (GVL) via both direct hydrogenation (DH) and transfer hydrogenation (TH). In DH of LA, the bimetallic catalyst achieved a 93.8% LA conversion efficiency with a 95.5% GVL selectivity and 38.2 mmol g−1 h−1 GVL productivity (under 130 °C, 2MPa H2 within 2 h), which are 6 and 40 times in comparison with monometallic Ni NPs@C and Fe NPs@C catalysts, respectively. In addition, the identical catalyst displayed a full conversion of LA with almost 100% GVL selectivity and 167.1 mmol g−1 h−1 GVL productivity at 180 °C within 0.5 h in TH of LA. Under optimal reaction conditions, the DH and TH catalytic performance of 500-Ni3Fe NPs@C(3:1) catalyst for converting LA to GVL is comparable to the state-of-the-art noble-based catalysts. The demonstrated capability of bimetallic catalyst design approach to introduce dual-catalytic functionality for DH and TH reactions could be adoptable for other catalysis processes.

Synthesis, X-ray diffraction studies, thermal behavior and catalytic investigation of Cu(II) complexes for levulinic acid-based polyol esters

Three new copper(II) complexes [Cu(Phe)(Phen)Cl].H2O (1), [Cu(Tyr)(Phen)Cl].H2O (2) and [Cu(Phe)(Tyr)Cl].H2O (3) (Phe = L-phenylalanine, Tyr = L-tyrosine and Phen = 1,10-phenanthroline) have been synthesized with aromatic amino acids and versatile organic 1,10-phenanthroline as mixed ligands and characterized by elemental analysis, FTIR, magnetic susceptibility, single crystal-XRD, powder-XRD, TGA/DTA and SEM techniques. The structural analysis of the complexes revealed that l-phenylalanine and l-tyrosine was coordinated to Cu(II) ion through amino nitrogen and carboxylate oxygen whereas, 1,10-phenanthroline was coordinated by the two nitrogen atoms. In all the cases, the Cu(II) ion has occupied the centre of the square pyramidal coordination, being equatorially bonded by both amino acids and 1,10-phenanthroline, while axially by chlorine atom. In addition, the thermal analysis (TGA/DTA) indicated the presence of lattice water molecules outside the coordination sphere. The catalytic activity of the synthesized complexes was further investigated via esterification of polyols (e.g., neopentyl glycol, trimethylolpropane and pentaerythritol) with biomass-derived levulinic acid (model acid) under mild reaction conditions. Indeed, the esterification reaction reveals that the Cu(II) complex with l-phenylalanine and 1,10-phenanthroline ligands exhibited a significantly high catalytic activity among them.

Alumina-supported Cu(II), Co(II), and Fe(II) complexes as catalyst for esterification of biomass-derived levulinic acid with trimethylolpropane (TMP) and pentaerythritol (PE) and upgrading via hydrogenation

A polyol-based ester was synthesized from biomass-derived bio-oil for application as a biolubricant. The bio-ester is biodegradable, non-toxic, and does not require mineral oil usage. Levulinic acid (LA), a major component obtained from bio-oil, was used for the catalytic esterification with two types of polyols, i.e., trimethylolpropane (TMP) and pentaerythritol (PE), in the presence of alumina-supported Cu(II), Co(II), and Fe(II) complexes as catalysts. Alumina-supported Cu(II), Co(II), and Fe(II) complexes [Cu(Tyr)(GA)]Cl-alumina, [Co(Tyr)(Amp)]Cl-alumina, and [Fe(Tyr)(Amp)]Cl-alumina were synthesized by the reaction of ligands [L-tyrosine (Tyr), Gallic acid (GA), and 2-aminopyridine (Amp)] with metal chloride salts. The catalysts were characterized by elemental analyses (CHN), magnetic susceptibility, Fourier transform infrared spectroscopy (FTIR), thermo-gravimetric analysis/differential thermal analysis (TGA/DTA), powder X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX) techniques. Catalytic performances of the synthesized complexes were investigated via esterification of levulinic acid with trimethylolpropane and pentaerythritol. In addition, the two best catalysts, [Cu(Tyr)(GA)]Cl and [Co(Tyr)(Amp)]Cl-alumina, were further employed for the in situ hydrogenation of levulinate esters at 120 °C to 130 °C and 7 bar to 8 bar H2 pressure for upgrading in a specially designed reactor. The alumina-supported catalysts were active, reusable, and exhibited their efficiency as heterogeneous catalysts for esterification and hydrogenation reactions for synthesizing ester-based oils.

Aqueous phase hydrogenation of levulinic acid to γ-valerolactone on supported Ru catalysts prepared by microwave-assisted thermolytic method

γ-Valerolactone (GVL), as a sustainable platform chemical, were produced through an aqueous phase hydrogenation of biomass-derived levulinic acid (LA) in the presence of supported ruthenium catalysts, in which the catalysts were prepared by solvent-free microwave-assisted thermolytic method. The effects of catalyst support, reaction media, pressure, temperature and LA initial concentration were investigated to obtain the optimum conditions for high γ-valerolactone yield. 5% Ru/AC catalyst exhibits a more superior catalytic performance compared with Ru/CNT, Ru/FCNT, Ru/γ-Al2O3-MW and Ru/γ-Al2O3-IM at 100°C and 2.0 MPa of 0.10 g/mL LA concentration in water solution. This superior performance is attributed to the higher dispersion of metallic Ru over coconut shell activated carbon. GVL can be produced with a good yield of > 99% under optimum conditions, and has the potential to provide a green, renewable platform for biotransformation.

Preparation of valeric acid and valerate esters from biomass-derived levulinic acid using metal triflates + Pd/C

The selective conversion of biomass-derived levulinic acid to produce valeric acid and valerate esters was successfully performed in the presence of H2, in which metal triflates and Pd/C were used as the catalysts.

Unraveling the structural properties and reactivity trends of Cu–Ni bimetallic nanoalloy catalysts for biomass-derived levulinic acid hydrogenation

Cu–Ni bimetallic nanoalloys as-prepared by an impregnation method exhibited superior catalytic activity with improved stability for levulinic acid hydrogenation to γ-valerolactone.

Catalytic conversion of biomass-derived levulinic acid into alcohols over nanoporous Ru catalyst

1,4-pentanediol or monohydric alcohol were achieved with high selectivity from levulinic acid under relatively mild conditions using nanoporous Ru.

Novel synthesis of Ru/OMS catalyst by solvent-free method: Selective hydrogenation of levulinic acid to γ-valerolactone in aqueous medium and kinetic modelling

γ-Valerolactone (GVL) is an important bio-derived molecule that could be used for the sustainable production of value-added chemicals and fuels. It is mainly synthesized by hydrogenation of levulinic acid by using supported ruthenium catalyst. Here we are reporting the synthesis of ruthenium supported on manganese oxide octahedral molecular sieve (OMS-2) catalyst prepared by different methods. Three different methods, i.e. reflux, hydrothermal and solventless protocols were used for the preparation of OMS-2. The prepared catalysts were used for the selective hydrogenation of biomass-derived levulinic acid (LA) to GVL using molecular hydrogen in water. Solventless synthesized OMS (OMS-2S) is energy efficient, rapid and economical way of synthesis. Among three different catalysts, Ru supported on solventless OMS-2 i.e. 1 wt% Ru/OMS-2S catalyst showed LA conversion of 99.9% and yield of 99.8% towards GVL in 1 h with the overall turnover frequency of 0.95 s−1 at mild conditions (100 °C, 30 atm H2). Different OMS-2 supported Ru catalysts showed a very high turnover frequency in comparison with those reported in literature for the synthesis of GVL. The specific textural and chemical properties of catalysts were characterized by various techniques. Moreover, 1 wt% Ru/OMS-2S catalyst was reusable up to four times without significant loss of activity and was very stable. By studying the effects of different process parameters, a kinetic model was developed based on LHHW type of mechanism. The apparent activation energy for LA hydrogenation to GVL is 11.75 kcal/mol.

Hydrogenation of biomass-derived levulinic acid to γ-valerolactone catalyzed by mesoporous supported dendrimer-derived Ru and Pt catalysts: An alternative method for the production of renewable biofuels

Generation 4 PAMAM-OH dendrimers were employed as templating agent for the synthesis of dendrimer-encapsulated Ru and Pt nanoparticles (Ru- or Pt-DENs). These DEN catalysts were then immobilized onto preformed mesoporous support materials (TiO2 and SiO2) using wet-impregnation method to produce heterogeneous catalysts. Ru- and Pt-DENs were characterized prior to immobilization using UV–vis (UV-vis) spectroscopy and high-resolution transmission microscopy (HRTEM). The average particle sizes for Ru- and Pt-DENs were determined to be 1.4±0.2 and 1.7±0.3nm, respectively. Supported solid catalysts were characterized using various techniques such N2 adsorption-desorption physisorption, powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) and HRTEM. Inductive coupled plasma-optical emission spectroscopy (ICP-OES) was used for the determination of metal loading on the support. The catalytic performance of these catalysts was investigated in the selective hydrogenation of levulinic acid (LA) to produce γ-valerolactone (GVL). The highest conversion was observed when unsupported catalysts (Ru-DENs and Pt-DENs) were used for all systems studied. The Ru catalyst displayed excellent activity as compared to Pt catalysts. All catalysts showed selectivity to γ-valerolactone up to 100%.

Hydrogenation of Biomass-Derived Levulinic Acid to Gamma- Valerolactone Using Polymer-Based Metal-Containing Catalysts

Nowadays the development of effective catalytic systems of selective hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) is of high importance. However, there is a lack of data concerning the use of polymer-based catalyst in this process. The possibility to use of Ru-containing catalysts on the basis of hypercrosslinked polystyrene (HPS) in hydrogenation of LA to GVL is discussed. Catalyst 5%-Ru/HPS is shown to be highly active and selective in hydrogenation of LA in aqueous medium (yield of GVL more than 99%) at mild reaction conditions (90 °C, 2 MPa of hydrogen partial pressure) and the absence of co-catalysts.