Optimización de las condiciones experimentales para la producción de biocombustibles de segunda generación que integran la glicerina

Con independencia del tiempo estimado para el agotamiento de las reservas de combustibles de origen fósil, es un objetivo prioritario la introducción paulatina de biocombustibles, no sólo con el fin de alargar el tiempo de uso de estos materiales fósiles, sino también para minimizar el impacto negativo de los gases de efecto invernadero sobre el clima. También se pueden incorporar los aceites vegetales usados para su reciclado, ya que constituyen una importante fuente de contaminación de las aguas continentales, principalmente en países con elevado consumo de aceites vegetales, como sucede en España y otros países mediterráneos. El objetivo general de la presente tesis doctoral ha sido avanzar en el estudio de diferentes métodos que permitan la valorización energética de los aceites usados y otros aceites refinados, como biocombustibles de segunda generación, en motores diesel, sin necesidad de modificarlos, pudiendo así contribuir a la sustitución de los combustibles fósiles. Para ello se considera esencial realizar un primer tratamiento en los aceites usados (“reciclado”), en el que se eliminen todas las impurezas que dichos aceites usados suelen contener. Estas impurezas son fundamentalmente partículas sólidas, que pueden generar oclusión en los filtros e inyectores y además, cantidades variables de agua, que pueden alterar la eficiencia de los posteriores tratamientos que el aceite reciclado pueda necesitar, bien para su uso directo, o su transformación en un biocombustible. En efecto, el aceite reciclado puede emplearse como materia prima para la obtención del biodiesel convencional, regulado por la norma EN 14214, o bien empleándolo directamente como biocombustible de segunda generación. En el primer caso, el biodiesel convencional puede emplearse puro como biocombustible en los actuales motores diesel, pero tiene como contrapartida el costo de su fabricación y la generación de una elevada cantidad de glicerina residual de costosa y difícil gestión. El aceite reciclado puede emplearse como biocombustible, pero siempre mezclado con diesel convencional de origen fósil y/o la presencia de alcoholes de cadena corta. De esta forma se podrán valorizar los aceites vegetales usados, una vez reciclados, de una forma eficiente sin necesidad de ningún tratamiento posterior y sin generar ningún tipo de residuo. Evaluar las posibilidades del empleo directo de aceites (reciclados o no aplicables en el consumo humano, como puede ser el aceite de ricino), empleando mezclas triples: diesel..

Review and Analysis of Alternatives for the Valorisation of Agro-Industrial Olive Oil By-Products

By-products and waste from olive production (agriculture) and the olive oil industry (mills and refineries) are an important environmental issue in Mediterranean areas. Industrial waste and by-products contain highly valuable components that can also be phytotoxic. This article reviews recent research on the valorisation of olive by-products under the bioeconomy strategy. The alternatives are classified according to the ‘bioeconomy value pyramid’, which prioritises higher value uses over the current energy and compost valorisation. Special attention is paid to the use of these by-products for animal feed that can be improved by reducing the content of saturated fatty acids (SFAs) and increase the polyunsaturated fatty acids amount considered beneficial in response to their use; this makes the food healthier for humans while simultaneously reducing feeding costs and the environmental impact of livestock

Production of a biodiesel-like biofuel without glycerol generation, by using Novozym 435, an immobilized Candida antarctica lipase

Background: Novozym 435, a commercial lipase from Candida antarctica, recombinant, expressed in Aspergillus niger, immobilized on macroporous acrylic resin, has been already described in the obtention of biodiesel. It is here evaluated in the production of a new biofuel that integrates the glycerol as monoglyceride (MG) together with two fatty acid ethyl esters (FAEE) molecules by the application of 1,3-selective lipases in the ethanolysis reaction of sunflower oil. Results: Response surface methodology (RSM) is employed to estimate the effects of main reaction. Optimum conditions for the viscosity, selectivity, and conversion were determined using a multifactorial design of experiments with three factors run by the software Stat Graphics version XV.I. The selected experimental parameters were reaction temperature, oil/ethanol ratio and alkaline environment. On the basis of RSM analysis, the optimum conditions for synthesis were 1/6 oil/EtOH molar ratio, 30°C, and 12.5 μl of NaOH 10 N aqueous solutions, higher stirring than 300 rpm, for 2 h and 0.5 g of biocatalyst. Conclusions: These obtained results have proven a very good efficiency of the biocatalyst in the studied selective process. Furthermore, it was allowed sixteen times the successive reuse of the biocatalyst with good performanc

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

Biocatalytic behaviour of immobilized Rhizopus oryzae lipase in the 1,3-selective ethanolysis of sunflower oil to obtain a biofuel similar to biodiesel

A new biofuel similar to biodiesel was obtained in the 1,3-selective transesterification reaction of sunflower oil with ethanol using as biocatalyst a Rhizopus oryzae lipase (ROL) immobilized on Sepiolite, an inorganic support. The studied lipase was a low cost powdered enzyme preparation, Biolipase-R, from Biocon-Spain, a multipurpose additive used in food industry. In this respect, it is developed a study to optimize the immobilization procedure of these lipases on Sepiolite. Covalent immobilization was achieved by the development of an inorganic-organic hybrid linker formed by a functionalized hydrocarbon chain with a pendant benzaldehyde, bonded to the AlPO4 support surface. Thus, the covalent immobilization of lipases on amorphous AlPO 4/sepiolite (20/80 wt %) support was evaluated by using two different linkers (p-hydroxybenzaldehyde and benzylamine-terephthalic aldehyde, respectively). Besides, the catalytic behavior of lipases after physical adsorption on the demineralized sepiolite was also evaluated. Obtained results indicated that covalent immobilization with the p-hydroxybenzaldehyde linker gave the best biocatalytic behavior. Thus, this covalently immobilized lipase showed a remarkable stability as well as an excellent capacity of reutilization (more than five successive reuses) without a significant loss of its initial catalytic activity. This could allow a more efficient fabrication of biodiesel minimizing the glycerol waste production. © 2014 by the authors.Grants from the Spanish Ministry of Economy and Competitiveness (Project ENE 2011-27017), Spanish Ministry of Education and Science (Projects CTQ2010-18126 and CTQ2011-28954-C02-02), FEDER funds and Junta de Andalucía FQM 0191, PO8-RMN-03515 and P11-TEP-7723 are gratefully acknowledged by the authors. We are also gratefully to Biocon®-Spain, for the kindly supply of the BIOLIPASE-R®. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer Reviewe

Synthesis, Performance and Emission Quality Assessment of Ecodiesel from Castor Oil in Diesel/Biofuel/Alcohol Triple Blends in a Diesel Engine

This research aims to promote the use of second-generation biofuels based mainly on Castor oil, which is not adequate for food use, and Sunflower oil as a standard reference for recycled oils. They have been applied in the production of Ecodiesel, a biofuel that integrates glycerol as monoglyceride, employing sodium methoxide as homogeneous catalyst and ethanol as solvent, but operating in milder conditions than in the synthesis of conventional biodiesel in order to obtain a kinetic control of the selective transesterification. The behavior of biofuels has been evaluated in a conventional diesel engine, operating as an electricity generator. The contamination degree was also evaluated from the opacity values of the generated smokes. The different biofuels here studied have practically no differences in the behavior with respect to the power generated, although a small increase in the fuel consumption was obtained in some cases. However, with the biofuels employed, a significant reduction, up to 40%, in the emission of pollutants is obtained, mainly with the blend diesel/castor oil/alcohol. Besides, it is found that pure Castor oil can be employed directly as biofuel in triple blends diesel/biofuel/alcohol, exhibiting results that are very close to those obtained using biodiesel or Ecodiesel

New Biofuel Integrating Glycerol into Its Composition Through the Use of Covalent Immobilized Pig Pancreatic Lipase

By using 1,3-specific Pig Pancreatic lipase (EC 3.1.1.3 or PPL), covalently immobilized on AlPO4/Sepiolite support as biocatalyst, a new second-generation biodiesel was obtained in the transesterification reaction of sunflower oil with ethanol and other alcohols of low molecular weight. The resulting biofuel is composed of fatty acid ethyl esters and monoglycerides (FAEE/MG) blended in a molar relation 2/1. This novel product, which integrates glycerol as monoacylglycerols (MG) into the biofuel composition, has similar physicochemical properties compared to those of conventional biodiesel and also avoids the removal step of this by-product. The biocatalyst was found to be strongly fixed to the inorganic support (75%). Nevertheless, the efficiency of the immobilized enzyme was reduced to half (49.1%) compared to that of the free PPL. The immobilized enzyme showed a remarkable stability as well as a great reusability (more than 40 successive reuses) without a significant loss of its initial catalytic activity. Immobilized and free enzymes exhibited different reaction mechanisms, according to the different results in the Arrhenius parameters (Ln A and Ea). However, the use of supported PPL was found to be very suitable for the repetitive production of biofuel due to its facile recyclability from the reaction mixture