Intraparticle diffusion model to determine the intrinsic kinetics of ethyl levulinate synthesis promoted by Amberlyst-15

Process optimization for enzymatic production of a valuable biomass-based ester from levulinic acid

The enzymatic production of isoamyl levulinate via esterification of isoamyl alcohol (IA) and levulinic acid (LA), a biomass-based platform chemical with attractive properties, in a solvent system has been performed in this study. For such a purpose, a low-cost liquid lipase (Eversa^® Transform 2.0) immobilized by physical adsorption via hydrophobic interactions (mechanism of interfacial activation) on mesoporous poly(styrenene-divinylbenzene) (PSty-DVB) beads was used as heterogeneous biocatalyst. It was prepared at low ionic strength (5 mmol.L^-1 buffer sodium acetate pH 5.0) and 25 ℃ using an initial protein loading of 40 mg.g^-1 of support. Maximum protein loading of 31.2 ± 2.8 mg.g^-1 of support and an immobilization yield of 83% was achieved. The influence of relevant factors (biocatalyst concentration and reaction temperature) on ester production was investigated using a central composite rotatable design (CCRD). Maximum acid conversion percentage of 65% was achieved after 12 h of reaction at 40 °C, 20% of mass of heterogeneous biocatalyst per mass of reaction mixture (20% m.m^-1), and LA:IA molar ratio of 1:1.5 in a methyl isobutyl ketone (MIBK) medium. The biocatalyst retained around of 30% of its initial activity after five consecutive esterification batches under optimal experimental conditions. The proposed experimental procedure can be considered as an acceptable green process (EcoScale score of 66.5), in addition to the fact that a new strategy is proposed to sustainably produce a valuable industrial ester (isoamyl levulinate) from biomass-based materials using an immobilized and low-cost commercial lipase as catalyst.

Performance Comparison of Polymeric and Silica-Based Multi-Bed Pervaporation Membrane Reactors during Ethyl Levulinate Production

A detailed numerical study of ethyl levulinate (EtLA) production with levulinic acid (LA) and ethanol (Et) in a multi-bed traditional reactor (MB-TR) and a silica-based and polymeric multi-bed pervaporation membrane reactors (MB-PVMR) was conducted and the efficiency of each design was studied under different operation conditions. Due to water production in the EtLA production process, water removal by a pervaporation system may improve process performance. Our results showed that MB-PVMR had higher performance compared with MB-TR. In addition, the silica membrane was more effective in water removal compared with the polymeric membrane. Therefore, higher LA conversion was achievable by a silica-based multi-bed pervaporation membrane reactor (SMB-PVMR). All the results were evaluated for percentage of water removal and LA conversion, based on variations in the Et/LA molar ratio, feed molar flow, reaction zone temperature, and catalyst loading. The results showed that water removal was higher than 95% and LA conversion of about 95% was attained by SMB-PVMR.

A biochar supported magnetic metal organic framework for the removal of trivalent antimony

Metal organic framework (MOF) nanoparticles are recognized for their effective removal of metal ions from aqueous systems. However, the application of nanoparticles in a powder form as synthesized is not practical and recovery is not easy. We prepared a recyclable magnetic MOF nanoparticle phase and used a widely available waste biomass to generate biochar to support magnetic nanoparticles applied in the treatment of aqueous antimony pollution. A mushroom waste biochar was used to support a magnetic UIO-66-2COOH (denoted as BSMU). Adsorption of trivalent antimony (Sb (III)) onto the BSMU was evaluated. The results showed that optimum conditions for preparation of the BSMU were the mass ratio of MMOF to biochar 4:1, the temperature 70 °C, the time 4 h, and the initiator 4 mM. Under such conditions, sorption capacity reached 56.49 mg/g for treatment of Sb (III) solution at 100 mg/L and pH 9.1. Alkaline conditions (such as pH 9.1) are more favorable for adsorption than acidic conditions, and coexisting ions including NO₃^-, Cl^-, SO₄^2-, and PO₄^3- had no significant negative effect in adsorption, and with the use of low dose, higher adsorption density achieved. The adsorption followed a pseudo second order kinetics model and Freundlich isotherm model. It resulted in a higher enthalpy changes (ΔH^θ) and activation energy (E_a) of 97.56 and 8.772 kJ/mol, respectively, and enhanced the rate pf random contact between antimony and the BSMU, as indicated by a higher entropy change (ΔS^θ) up to 360 J/mol·K. As a result, it readily absorbs antimony. These adsorption properties identified in this study would provide a valuable insights into the application of nanoparticles loaded biochar from abundant biomass in environmental remediation.

Reactive Chromatography Applied to Ethyl Levulinate Synthesis: A Proof of Concept

Levulinic acid (LA) has been highlighted as one of the most promising platform chemicals, providing a wide range of possible derivatizations to value-added chemicals as the ethyl levulinate obtained through an acid catalyzed esterification reaction with ethanol that has found application in the bio-fuel market. Being a reversible reaction, the main drawback is the production of water that does not allow full conversion of levulinic acid. The aim of this work was to prove that the chromatographic reactor technology, in which the solid material of the packed bed acts both as stationary phase and catalyst, is surely a valid option to overcome such an issue by overcoming the thermodynamic equilibrium. The experiments were conducted in a fixed-bed chromatographic reactor, packed with Dowex 50WX-8 as ion exchange resin. Different operational conditions were varied (e.g., temperature and flow rate), pulsing levulinic acid to the ethanol stream, to investigate the main effects on the final conversion and separation efficiency of the system. The effects were described qualitatively, demonstrating that working at sufficiently low flow rates, LA was completely converted, while at moderate flow rates, only a partial conversion was achieved. The system worked properly even at room temperature (303 K), where LA was completely converted, an encouraging result as esterification reactions are normally performed at higher temperatures.

Smart ion imprinted polymer for selective adsorption of Ru(Ⅲ) and simultaneously waste sample being transformed as a catalyst

In this work, a temperature-sensitive block polymer PDEA-b-P(DEA-co-AM) was synthesized and then introduced into the preparation of a smart Ru(Ⅲ) imprinted polymer (Ru-IIP) to selectively adsorption Ru(Ⅲ) first. Then the waste Ru-IIP was converted into a catalyst in-situ for recycle. The structure and morphology of the prepared polymer were characterized by Fourier transform infrared spectrometer, Scanning electron microscope, BET surface area and Thermogravimetric analysis. The adsorption properties of the synthesized smart material were investigated in terms of adsorption pH, adsorption kinetics and adsorption isotherm. Results documented that the optimal adsorption temperature and pH were 35 °C and 1.5 respectively, the maximum adsorption capacity was 0.153 mmol/g, and the adsorption processes of Ru-IIP were more suitable to be expressed by pseudo-first-order kinetic and Langmuir model. The selectivity studied in different binary mixed solutions showed that Ru-IIP has good selectivity, and reusability results showed that Ru-IIP still maintains a good adsorption effect after 8 cycles. In addition, the waste Ru-IIP, a Ru(Ⅲ) remained waste sample was employed as the catalyst for the synthesis of imines, and result showed the mass of adsorbent would reduce after the completion of catalysis, which could not only catalyze the reaction but also reduce pollution.

A Theoretical Analysis on a Multi-Bed Pervaporation Membrane Reactor during Levulinic Acid Esterification Using the Computational Fluid Dynamic Method

Pervaporation is a peculiar membrane separation process, which is considered for integration with a variety of reactions in promising new applications. Pervaporation membrane reactors have some specific uses in sustainable chemistry, such as the esterification processes. This theoretical study based on the computational fluid dynamics method aims to evaluate the performance of a multi-bed pervaporation membrane reactor (including poly (vinyl alcohol) membrane) to produce ethyl levulinate as a significant fuel additive, coming from the esterification of levulinic acid. For comparison, an equivalent multi-bed traditional reactor is also studied at the same operating conditions of the aforementioned pervaporation membrane reactor. A computational fluid dynamics model was developed and validated by experimental literature data. The effects of reaction temperature, catalyst loading, feed molar ratio, and feed flow rate on the reactor’s performance in terms of levulinic acid conversion and water removal were hence studied. The simulations indicated that the multi-bed pervaporation membrane reactor results to be the best solution over the multi-bed traditional reactor, presenting the best simulation results at 343 K, 2 bar, catalyst loading 8.6 g, feed flow rate 7 mm³/s, and feed molar ratio 3 with levulinic acid conversion equal to 95.3% and 91.1% water removal.

Production of Sustainable Biochemicals by Means of Esterification Reaction and Heterogeneous Acid Catalysts

In recent years, the use of renewable raw materials for the production of chemicals has been the subject of different studies. In particular, the interest of the present study was the use of oleins, mixtures of free fatty acids (FFAs), and oleic acid to produce bio-based components for lubricants formulations and the investigation of the performance of a styrene-divinylbenzene acid resin (sPSB-SA) in the esterification reaction of fatty acids. This resin has shown good activity as a heterogeneous catalyst and high stability at elevated temperatures (180 °C). It was tested in the esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol. In particular, the esterification reactions were performed in a steel stirred batch reactor and a PBR loop reactor. Tests were conducted varying the reaction conditions, such as alcohol type, temperature, reaction time, and catalysts, both homogeneous and heterogeneous ones. From the obtained results, acid resin (both in reticulated and not-reticulated form) showed high activity in esterification reaction of oleic acid with 1,3-propanediol and of oleic acid with glycerol and good resistance to the deactivation; thus, they can be considered promising candidates for future applications in continuous devices. Viscosity tests were performed, underlining the good properties of the obtained products as lubricant bases.