Alberto Gonzalo

Prediction of normalized biodiesel properties by simulation of multiple feedstock blends

A continuous process for biodiesel production has been simulated using Aspen HYSYS V7.0 software. As fresh feed, feedstocks with a mild acid content have been used. The process flowsheet follows a traditional alkaline transesterification scheme constituted by esterification, transesterification and purification stages. Kinetic models taking into account the concentration of the different species have been employed in order to simulate the behavior of the CSTR reactors and the product distribution within the process. The comparison between experimental data found in literature and the predicted normalized properties, has been discussed. Additionally, a comparison between different thermodynamic packages has been performed. NRTL activity model has been selected as the most reliable of them. The combination of these models allows the prediction of 13 out of 25 parameters included in standard EN-14214:2003, and confers simulators a great value as predictive as well as optimization tool.

Methanolysis and ethanolysis of animal fats: a comparative study of the influence of alcohols.

Biodiesel from animal fats with methanol and ethanol was produced in the presence of sodium methoxide and sodium ethoxide as catalysts. Two samples of pork fats and one natural beef tallow were directly transesterified with a good final product yield; 87.7%, 86.7% and 86.3% for methanolysis and 78.4%, 82.6% and 82.7% for ethanolysis, respectively. Methyl ester content was also determined, being higher than 96.5 wt. % for all the samples prepared, the presence of natural C17:0 in animal fats makes it necessary to correct the method proposed in the standard EN 14103 (2003). Biodiesel density at 15 oC of the samples was between 870 and 876 kg/m3, within the acceptance range of standard EN 14214, dynamic viscosity at 40 oC of the produced biodiesels, in the range of 4.5 to 5.16 mm2/s, also fulfills requirements of EN 14214 standard. The iodine value is much lower than the superior limit established by EN 14214 standard but oxidation stability (OSI) is lower than the required limit, 6 h, of the standard, which can be attributed to the lack of natural antioxidants in tallows.

Semichemical pulping of Miscanthus giganteus. Effect of pulping conditions on some pulp and paper properties

Miscanthus is an interesting raw material for pulp production, it is a high yield low maintenance plant with a high cellulose and hemicellulose content. Its semichemical pulp can be beneficial in paper for cardboard production process, which nowadays is usually made from secondary fibers, by increasing the mechanical properties of the paper produced. In this study, the influence of the percentage of NaOH used related to the dry Miscanthus weight, digestion time and refining time on some pulp and paper properties have been studied and compared with pulp obtained from commercial fluting paper (CF). Fiber size distribution of the Miscanthus pulp was found to contain a higher fines (less than 0.2mm) percentage than the CF pulp. Hand-sheets made from Miscanthus pulp showed better mechanical properties than the ones made with the CF pulp. CMT, RCT and CCT indexes were higher when using 100% Miscanthus pulp or mixtures of Miscanthus and CF pulp. The only property which worsened was Gurley porosity. Of the three operational variables changed, refining time exerts the most significant influence on the pulp and paper properties measured.

Bio-Oil Hydrotreatment for Enhancing Solubility in Biodiesel and the Oxydation Stability of Resulting Blends

The major challenge for the pyrolytic conversion of lignocellulosic materials into crude bio-oil is the poor quality of the final product. Several strategies (addition of solvents, production of emulsions, and extraction with biodiesel) have been studied to improve its fuel properties. The extraction with biodiesel is an interesting solution because it allows direct utilization of some bio-oil fractions as fuels. However, fraction extracted with biodiesel is typically between 10 and 18 wt. %. In this paper we studied mild hydrotreatment of pyrolysis oil to enhance its solubility in biodiesel. The study was conducted with BTG and Amaron oils hydrotreated at temperatures between 200 and 325°C in the presence of Ru/C catalyst. Hydrotreated oils generated three phases: top oil (light hydrocarbons), middle aqueous phase and bottom heavy oil phase. Each of the phases was characterized and the content of acetic acid, phenols, aromatic compounds, and linear alkane hydrocarbons quantified. The upgraded bio-oils were more soluble in biodiesel than the crude bio-oils, obtaining blends with up to 48 and 38 wt. % for the BTG and Amaron bio-oil, respectively. Some of the fuel properties of the resulting blends are also reported here.

Density of alkyl esters and its mixtures

Biodiesel density is a key parameter in biodiesel simulations and process development. In this work we selected, evaluated and improved two density models, one theoretical (Rackett-Soave) and one empirical (Lapuertas method) for methanol based biodiesels (FAME) and ethanol based biodiesel (FAEE). For this purpose, biodiesel was produced from vegetable oils (sunflower, rapeseed, soybean, olive, safflower and other two commercial mixtures of vegetable oils) and animal fats (edible and crude pork fat and beef tallow) using both methanol and ethanol for the transesterification reactions, and blended to get 21 FAME and 21 FAEE, reporting their density and detailed composition. Bibliographic data have also been used. The Rackett-Soave method has been improved by the use of a new acentric factor correlation, whereas the parameters of the empirical one are improved by considering a bigger density data bank. Results show that the evaluated models could be used to estimate the biodiesel density with a good grade of accuracy but the performed modifications improve the accuracy of the models: ARD (%) for FAME; 0.33, and FAEE; 0.26, both calculated with the modification of Rackett-Soave method and ARD (%) for FAME; 0.40 calculated with the modification of the Lapuertas method).