Microwave-assisted technology effectively enhances heterogeneously catalyzed transesterification reactions for production of fatty acid methyl esters (FAME), which are the components of biodiesel. FAME are key intermediates for sustainable aviation fuels. Nevertheless, the impact of the microwave-absorbing capacity of a catalyst on catalytic performance is still ambiguous. Herein, we successfully synthesized a microwave-absorbing catalyst (CaO-CNT) and a microwave-transparent catalyst (CaO-SiO2) and evaluated the catalytic performance in the transesterification reaction of palm oil and methanol. The microwave-absorbing capacity of the catalyst enhanced the catalytic performance in the microwave field, and the dielectric loss (tan δε = 0.172) of CaO-CNT was much stronger than that of CaO-SiO2 (tan δε = 0.002), demonstrating a superior microwave-absorbing capacity. The CaO-CNT in situ provided essential energy to reactants heated by microwave heating and the transesterification conversion by 11.44%, while that of CaO-SiO2 only increased by 0.83%. Notably, CaO-CNT saves 15% of energy consumption and reduces 303.72 kg of CO2 per ton of FAME produced compared to that of the microwave-transparent catalyst, CaO-SiO2.

ABSTRACT Heteroleptic and homoleptic complexes of zinc with phenoxyimine and phenoxyamidine ligands are used as alternatives to currently used tin catalysts in the transesterification reaction of methyl acrylate and N,N‐ dimethylethanolamine in the synthesis of N,N‐ dimethylaminoethyl acrylate. A large screening of phenoxyimine and three generations of phenoxyamidine ligands has been undertaken and used to determine the best catalysts in terms of conversion and selectivity. All of the catalysts tested show significant improvement in activity over catalysts currently well‐established in industrial processes such as dibutyltin oxide or Ti(O i Pr) 4 . The catalytic charges can be decreased significantly (10–20×) still affording good conversions and selectivities. A series of heteroleptic and homoleptic zinc complexes with phenoxyimine and phenoxyamidine ligands have been tested for the transesterification of methyl acrylate with N,N ‐dimethylethanolamine. All the catalysts demonstrated a substantial increase in activity compared to dibutyltin oxide, a well‐established catalyst that is currently used in industry for this reaction.

Biodiesel, a sustainable and renewable energy source, is a promising alternative to fossil fuels. The transesterification process of biodiesel production effectively captures memory effects in reaction kinetics. In this study, we developed two fractional order models of the chemical catalytic transesterification reaction to explore the memory effects of the reaction kinetics utilizing two different non-singular kernel methods: Caputo-Fabrizio and Atangana-Baleanu in the Caputo sense. We compared the results with experimental data of biodiesel production and demonstrated the existence and uniqueness of the solution for the fractional system. A sensitivity analysis is performed using the Latin hypercube sampling method to evaluate the impact of various parameters on biodiesel production, followed by the computation of partial rank correlation coefficients based on Pearson’s correlation coefficient. We exhibit the dynamic behavior of all reactants corresponding to these fractional models with the variation of fractional order and the memory rate parameter. Additionally, we display the memory effect through the surface plots for biodiesel production by varying fractional order, molar ratio, and ultrasound frequency. Our numerical comparison with experimental data identifies the fractional-order value for the best fit of biodiesel production and can be increased by applying optimal control on ultrasound frequency.

This review paper has examined, though not exhaustively, the synthesis of biodiesel through the transesterification reaction of non-edible and waste oils utilizing chemically-based heterogeneous catalysts activated by microwave irradiation. The production of biodiesel from such feedstock oils can significantly enhance the commercialization of biodiesel, as it presents a cost-effective alternative to fresh edible oils, thereby lowering raw material expenses. Another potential reduction in costs may stem from employing heterogeneous catalysts alongside microwave heating, which utilizes less energy and necessitates a shorter transesterification reaction time, exhibiting improved reaction kinetics without compromising the overall yield of biodiesel, in contrast to traditional heating methods. The findings from the reviewed studies indicate that microwave heating may surpass conventional heating in all assessed parameters, despite the more controlled reaction conditions associated with the former. It has also been observed that the acceleration of the transesterification reaction via microwave heating cannot be directly compared to that achieved through conventional heating under otherwise identical conditions. Moreover, microwave-assisted heterogeneously catalyzed transesterification reactions are distinguished by the emergence of hot spots, superheating, and selective heating of particular species. These phenomena improve the efficiency of the heating process, resulting in a higher rate of transesterification while minimizing the generation of by-products. The efficacy of heterogeneous catalysts in facilitating transesterification reactions is remarkable, showcasing high reactivity, stability, and selectivity when integrated with microwave technology.

This study investigated the use of deep eutectic solvents (DESs) for separating azeotropic mixtures of alcohol–ester systems. The DESs were composed of choline chloride combined with either malonic or glutaric acid. Liquid–liquid equilibria (LLE) data and phase diagrams were obtained for pseudoternary systems including ethanol–n-propyl formate, n-propanol–n-propyl formate, and n-butanol–n-propyl formate at temperatures of 293.15 and 313.15 K and 101.3 kPa. Liquid–liquid tie lines were determined and analyzed by using 1H NMR spectroscopy. The separation performance of DESs was characterized by distribution coefficients and selectivity values. The studied DESs demonstrated the ability to catalyze transesterification reactions. Conversion values in the organic phase were determined as a function of alcohol concentration. This research provides valuable insight into the potential use of choline-chloride-based DESs for separating azeotropic mixtures, particularly in alcohol–ester systems while also revealing their catalytic properties in transesterification reactions.

Study on the properties of epoxy insulating materials degradation and recycled materials based on 2,4,6-tris(dimethylaminomethyl)phenol catalyzed transesterification reaction

Effects of Ce/Ca/Mg-compound supports on KF catalyst and reaction kinetics of ethylene carbonate transesterification

One-pot conversion of non-edible oil into sustainable biodiesel using novel bifunctional heterogeneous catalyst

This work aimed at valorizing non-edible seed oils from some plants found in Cameroon videlicet Acacia hockii (AH), Garcinia livingstonei (GL) and Moringa oleifera (MO), through production of biodiesel. Two extraction methods used were; the Soxhlet extraction and surfactant assisted extraction with sodium dodecyl sulphate (SDS) as surfactant. The extracted oils were characterized using physicochemical parameters. The characterized oils were used to synthesize biodiesels via acid and base catalyzed transesterification reactions. The purification of the biodiesels was done using chromatographic columns. The biodiesels obtained were also characterized using physicochemical analysis in a manner similar to the oils with additional parameters like cold f low properties, f lammability, ignition qualities and cetane number determinations. Qualitative analysis was realized using the Fourier Transformed Infrared Spectrophotometer (FT-IR). The Soxhlet extraction method gave higher yields for all the plants with MO being the highest, compared to the surfactant assisted extractions. The results from the physicochemical properties of the oils were as follows: specific gravity, 0.876 g/mL, 0.843 g/mL and 0.865 g/mL for AH, GL, and MO. The free fatty acid contents of the oils were 0.436% FFA, 0.547% FFA and 1.60% FFA for AH, GL, and MO respectively. The saponification values gave 143.03 mgKOH/g, 72.93 mgKOH/g, 126.22 mgKOH/g for AH, GL and MO in that order. Iodine values for the oils were 46.54 mgI2/g, 22.41 mgI2/g, 68.10 mgI2/g for AH, GL, and MO, respectively. The peroxide values gave 10.05 meq/kg, 8.50 meq/kg, 8.0 meq/kg for AH, GL, and MO, respectively. The kinematic viscosities were 21.0 mm2/s, 22.0 mm2/s and 43.0 mm2/s for AH, GL, and MO, respectively. The acid catalyzed reaction gave greater crude yields of 90.00% for all three plants while the base catalyzed reaction gave, 87.00% (AH), 84.00% (GL) and 74.00% (MO). The purified biodiesel samples had the following acid numbers: 0.028% FFA for BAH, 0.022% FFA for BGL, and 0.028% FFA for BMO. The kinematic viscosities values for biodiesel were 4.00 mm2/s, 4.23 mm2/s, and 5.22 mm2/s for BAH, BGL, and BMO, respectively. The cetane numbers of the synthesized biodiesel samples were 142.73 (BAH), 167.29 (BGL), and 82.40 (BMO). The IR spectra of the biodiesels corroborated the chemical make-up of biodiesel. Hence non-edible seed oils from the Cameroon rich bioresources can be valorized in biodiesel synthesis and other forms of green energy production in Cameroon and beyond.

Fe-doped TiO2 nanocrystals as highly efficient catalysts for heterogeneous catalytic transesterification of coconut oil

Transesterification of DMC with ethanol over K2CO3/Al2O3: The structure-performance relationship and catalytic mechanism

Biodiesel is a mixture of fatty acid alkyl esters (FAAEs) mainly produced via transesterification reactions among triglycerides and short-chain alcohols catalyzed by chemical catalysts (e.g., KOH, NaOH). Lipase-assisted enzymatic transesterification has been proposed to overcome the drawbacks of chemical synthesis, such as high energy consumption, expensive separation of the catalyst from the reaction mixture and production of large amounts of wastewater during product separation and purification. However, one of the main drawbacks of this process is the enzyme cost. In recent years, nano-immobilized lipases have received extensive attention in the design of robust industrial biocatalysts for biodiesel production. To improve lipase catalytic efficiency, magnetic nanoparticles (MNPs) have attracted growing interest as versatile lipase carriers, owing to their unique properties, such as high surface-to-volume ratio and high enzyme loading capacity, low cost and inertness against chemical and microbial degradation, biocompatibility and eco-friendliness, standard synthetic methods for large-scale production and, most importantly, magnetic properties, which provide the possibility for the immobilized lipase to be easily separated at the end of the process by applying an external magnetic field. For the preparation of such effective magnetic nano-supports, various surface functionalization approaches have been developed to immobilize a broad range of industrially important lipases. Immobilization generally improves lipase chemical-thermal stability in a wide pH and temperature range and may also modify its catalytic performance. Additionally, different lipases can be co-immobilized onto the same nano-carrier, which is a highly effective strategy to enhance biodiesel yield, specifically for those feedstocks containing heterogeneous free fatty acids (FFAs). This review will present an update on the use of magnetic iron oxide nanostructures (MNPs) for lipase immobilization to catalyze transesterification reactions for biodiesel production. The following aspects will be covered: (1) common organic modifiers for magnetic nanoparticle support and (2) recent studies on modified MNPs-lipase catalysts for biodiesel production. Aspects concerning immobilization procedures and surface functionalization of the nano-supports will be highlighted. Additionally, the main features that characterize these nano-biocatalysts, such as enzymatic activity, reusability, resistance to heat and pH, will be discussed. Perspectives and key considerations for optimizing biodiesel production in terms of sustainability are also provided for future studies.

Effective transesterification of castor oil to biodiesel catalyzed by novel carbon-based calcium composite

In this study, the conversion of crude Jatropha curcas oil into biodiesel through transesterification was investigated in the presence of heterogeneous solid catalysts under supercritical methanol environment. The principal impetuses catalyzing the expansion in optimal biodiesel production are primarily attributed to the increasing demand for sustainable energy sources, the availability of raw materials, and innovations in production methodologies. To maintain the optimization, 6 wt% and 10 wt% of zinc oxide (ZnO) were incorporated into gamma-alumina (γ-Al2O3) through a wet impregnation method followed by calcination at 900 °C. Furthermore, the study examined the effect of alcohol/oil molar ratio, reaction temperature, and reaction time on the process to achieve maximum biodiesel production. The study revealed that a catalyst consisting of 10 wt% ZnO on γ-Al2O3 exhibited exceptional performance with a biodiesel yield of 95.64% under the reaction conditions of a molar ratio of 1:40 oil to methanol, a temperature of 300 °C, a pressure of 9 MPa, and a residence time of 3 min compared to the yield of 100% under same condition at residence time of 9 min. After thorough investigation, the kinetics of the catalytic transesterification reaction were elucidated, and suitable kinetic parameters were proposed.

Vitrimers are polymer networks with covalent bonds that undergo reversible exchange reactions and rearrange their topology in response to an external stimulus. The temperature-dependent change in viscoelastic properties is conveniently adjusted by selected catalysts. In these thermo-activated systems, the lack in spatial control can be overcome by using photolatent catalysts. Herein, we advance this concept to locally manipulate bond exchange reactions on a single digit microscale level. For this, we synthetize a linkable non-ionic photoacid generator, which is covalently attached to a thiol-click photopolymer. UV induced deprotection of the photoacid yields a strong immobilized sulfonic acid species, which is able to efficiently catalyze transesterification reactions. Covalent attachment of the formed acid prevents migration/leaching processes and enables a precise tuning of material properties. As proof of concept, positive toned microstructures with a resolution of 5 μm are inscribed in thin films using direct two-photon absorption laser writing and subsequent depolymerization. In addition, the possibility to locally reprogram bulk material properties is demonstrated by performing a post-modification reaction with ethylene glycol and carboxylic acids. The Young's modulus is varied between 3.3 MPa and 11.9 MPa giving rise to the versatility of the newly introduced catalysts for creating light processable and transformable materials.

Heterogeneous catalysts, basic, acidic or bifunctional, can catalyze transesterification reactions where the raw material has a significant content of FFA fatty acids, such as used cooking oils or other lipid-based residues, which do not have the purity required for homogeneous catalysis, in which case the purity of the triglycerides above 99.5% is the first condition for the initiation of the reaction, to avoid saponification. In this work, a green supported catalyst was developed, using bacterial cellulose as catalytic support and biodegradable superbase as a chemical compound, for transesterification reaction to obtain alkyl esters, yielding over 99% of its content at 70 °C temperature and 7.5% catalyst loading (1.5/20 w/w catalyst:oil). A Plackett-–Burman design was used for screening experiments to explore the main effect in terms of catalytic activity and performance of the triglyceride conversion reaction.

Acid–base bifunctional ZnNbCl/eg-C3N4 materials towards catalytic synthesis of dimethyl carbonate via transesterification of ethylene carbonate

Over the past several decades, people from many nations have adopted and supported using biodiesel energy sources due to their accessibility and advantages in reducing CO2 and H.C. emissions to the environment. Today, biodiesel is recognized as a sustainable alternative energy source. Commercially, biodiesel was produced by converting homogenous oil treated with a catalyst like NaOH or KOH in Alcohol. These homogeneous catalysts are hazardous to the environment and cannot be recycled. As an alternative, this research article focuses on biodiesel production from a 1:1 blend of Simarubha glauca (Laxmitharu in Kannada) and Azadirachta indica (Neem) triglyceride via acid-base catalyzed transesterification reaction. The heterogeneous-based graphene-doped CaO was used as a catalyst obtained through the calcination method by doping it with graphene oxide by the hummers’ method. SEM, FTIR, and XRD were used to characterize the GaO-CaO catalyst. The results predict that the prepared catalyst yielded a high percentage of ASFAME (94.0%) and meets the quality as per ASTM standards 6751D.

Optimization of biodiesel yield from non-food karanja seed oil: Characterization and assessment of fuel properties

Homogenizer-intensified amidation of free fatty acids in waste cooking oil for biodiesel production