Proposed kinetic mechanism of biodiesel production through lipase catalysed interesterification with a methyl acetate acyl acceptor and ionic liquid [BMIM][PF6] co-solvent

Biodiesel Is Dead: Long Life to Advanced Biofuels—A Comprehensive Critical Review

Many countries are immersed in several strategies to reduce the carbon dioxide (CO2) emissions of internal combustion engines. One option is the substitution of these engines by electric and/or hydrogen engines. However, apart from the strategic and logistical difficulties associated with this change, the application of electric or hydrogen engines in heavy transport, e.g., trucks, shipping, and aircrafts, also presents technological difficulties in the short-medium term. In addition, the replacement of the current car fleet will take decades. This is why the use of biofuels is presented as the only viable alternative to diminishing CO2 emissions in the very near future. Nowadays, it is assumed that vegetable oils will be the main raw material for replacing fossil fuels in diesel engines. In this context, it has also been assumed that the reduction in the viscosity of straight vegetable oils (SVO) must be performed through a transesterification reaction with methanol in order to obtain the mixture of fatty acid methyl esters (FAMEs) that constitute biodiesel. Nevertheless, the complexity in the industrial production of this biofuel, mainly due to the costs of eliminating the glycerol produced, has caused a significant delay in the energy transition. For this reason, several advanced biofuels that avoid the glycerol production and exhibit similar properties to fossil diesel have been developed. In this way, “green diesels” have emerged as products of different processes, such as the cracking or pyrolysis of vegetable oil, as well as catalytic (hydro)cracking. In addition, some biodiesel-like biofuels, such as Gliperol (DMC-Biod) or Ecodiesel, as well as straight vegetable oils, in blends with plant-based sources with low viscosity have been described as renewable biofuels capable of performing in combustion ignition engines. After evaluating the research carried out in the last decades, it can be concluded that green diesel and biodiesel-like biofuels could constitute the main alternative to addressing the energy transition, although green diesel will be the principal option in aviation fuel.

Biodiesel at the Crossroads: A Critical Review

The delay in the energy transition, focused in the replacement of fossil diesel with biodiesel, is mainly caused by the need of reducing the costs associated to the transesterification reaction of vegetable oils with methanol. This reaction, on an industrial scale, presents several problems associated with the glycerol generated during the process. The costs to eliminate this glycerol have to be added to the implicit cost of using seed oil as raw material. Recently, several alternative methods to convert vegetable oils into high quality diesel fuels, which avoid the glycerol generation, are being under development, such as Gliperol, DMC-Biod, or Ecodiesel. Besides, there are renewable diesel fuels known as “green diesel”, obtained by several catalytic processes (cracking or pyrolysis, hydrodeoxygenation and hydrotreating) of vegetable oils and which exhibit a lot of similarities with fossil fuels. Likewise, it has also been addressed as a novel strategy, the use of straight vegetable oils in blends with various plant-based sources such as alcohols, vegetable oils, and several organic compounds that are renewable and biodegradable. These plant-based sources are capable of achieving the effective reduction of the viscosity of the blends, allowing their use in combustion ignition engines. The aim of this review is to evaluate the real possibilities that conventional biodiesel has in order to success as the main biofuel for the energy transition, as well as the use of alternative biofuels that can take part in the energy transition in a successful way.

Enzymatic catalysis for sustainable production of high omega-3 triglyceride oil using imidazolium-based ionic liquids

Two different fish oil preparations, namely triglycerides and ethyl esters containing, respectively, 30.02% and 74.38% of omega-3 fatty acids, were employed as the substrates for transesterification. Catalyzed by immobilized lipase using imidazolium-based ionic liquid systems, the total content of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in the resulting triglyceride reached 63.60% when 4% hydrophobic ionic liquid was used, which was 11.74% higher than that of the triglyceride produced in a solvent-free reaction system. The activation energy of the product (triglyceride-type fish oil) was 173.64 KJ mol-1, which was not significantly different from that of the commercial ethyl ester-type fish oil, so were the other thermal oxidative kinetic parameters. The kinetic parameters depicting the thermal and oxidative stability of the fish oil product provide the basis for industrial processing, storage, and applications.

Enhanced Ricinoleic Acid Preparation Using Lipozyme TLIM as a Novel Biocatalyst: Optimized by Response Surface Methodology

Ricinoleic acid (RA) is an important raw material for plasticizers, emulsifiers, and nanomaterials. In this work, a green and efficient method was developed for RA production. Results showed that Lipozyme TLIM can be used as a novel biocatalyst to catalyze the hydrolysis of castor oil (CO) for RA preparation. Response surface methodology (RSM) was used to evaluate and optimize the effects of reaction variables on the hydrolysis of CO. Reaction conditions were optimized as follows: 41.3 °C, enzyme load 8.9%, 39.2 h, and 40:1 molar ratio of water to oil. Under these optimized reaction variables, the maximum hydrolysis ratio of CO (96.2 ± 1.5%) was obtained. The effect of hydrolysis variables on the reaction was as follows: enzyme load > hydrolysis time > temperature. In conclusion, this is a green, simple, and efficient method for RA preparation and can provide a good alternative method for RA industrial production.

An alternative method for production of microalgal biodiesel using novel Bacillus lipase

In this study, enzymatic interesterification is carried out using encapsulated lipase as biocatalyst with methyl acetate as acyl acceptor in a solvent-free system. Lipase, isolated from a marine bacterial isolate, Bacillus sp.S23 (KF220659.1) was immobilized in sodium alginate beads. This investigation elaborated on the effects of various parameters, namely enzyme loading, temperature, water, molar ratio, reaction time and agitation for interesterification. The study resulted in the following optimal conditions: 1.5 g immobilized lipase, 1:12 molar ratio of oil to methyl acetate, 35 °C, 8 % water, 60 h reaction time, 250 rpm of agitation. With the standardized condition, the maximum conversion efficiency was 95.68 %. The immobilized beads, even after ten cycles of repeated usage showed high stability in the presence of methyl acetate and no loss of lipase activity. The microalgal biodiesel composition was analyzed using gas chromatography. The current study was efficient in using immobilized lipase for the interesterification process, since the method was cost-effective and eco-friendly, no solvent was involved and the enzyme was encapsulated in a natural polymer.