Luis A. Rios

Disponibilidad de Variedades de Pastos y Forrajes como Potenciales Materiales Lignocelulósicos para la Producción de Bioetanol en Colombia

A review on the most common species of grasses and forages in Colombia to determine their potential use as lignocellulosic materials for the production of fuels like bioethanol and biobutanol is presented. For this, location, production yield per hectare and per year, lignocellulosic composition and ethanol yield are considered as main characteristics for determining their potential use. As result, elephant grass and king grass, are presented as the most appropriate ones for their exploration in biofuel production processes with green forages yields per acre per year between 360 and 400 ton and between 240 and 360 ton, respectively. Furthermore based in its cellulose and hemicellulose concentration, theoretical ethanol yields of 466,9 L/dry ton of elephant grass and 449,7 L/dry ton of king grass are obtained.

Síntesis y caracterización de adhesivos reposicionables de poliuretano dispersos en agua, obtenidos a partir de aceite de castor maleinizado

This work focused on the production of aqueous dispersions of polyurethane using the emulsification method by phase inversion. For the synthesis two polyols were employed, viz. a commercial polyester and Maleinizated Castor Oil (MACO), with two diisocyanates: one aromatic, toluene diisocyanate (TDI) and another aliphatic, hexamethylene diisocyanate (HDI), which are not common for this application. Citric acid was used as internal emulsifier which is inexpensive and readily available. The parameters were the amount of citric acid and the mole ratio of isocyanate groups to hydroxyl (NCO/OH), generating a 32 factorial design, with minimization of the sedimented solids. The surface methodology was used to obtain a quadratic polynomial equation by multiple regression analysis. Polyurethanes synthesized were evaluated for their mechanical and adhesive properties (tack, loop tack, hold, peel). These measurements allowed classifying the polyurethanes synthesized as repositionable adhesives, for use in labels.

Madera, un Potencial Material Lignocelulósico para la Producción de Biocombustibles en Colombia

The availability of woody resources in Colombia is studied for evaluating their potential for the production of ethanol as a fuel. The diversity of species, the planting and growth conditions of trees and the chemical composition of their woods were analyzed. The study shows that about half of the forested area for commercial purposes is formed by conifers, among which Pinus patula, Pinus caribaea and Eucalyptus grandis are the most abundant. Also, the species Pinus patula, Eucalyptus camaldulensis and Eucalyptus grandis showed the highest yield and Pinus caribaea, Pinus patula and Eucalyptus camaldulensis with the highest cellulose content. Given the great technological and highly competitive commercial products derived from pine and eucalyptus, Colombia should take advantage of its situation and promote reforestation with these native species.

Síntesis de Aditivos para Biodiesel a partir de Modificaciones Químicas de la Glicerina

Resumen Se muestran los resultados experimentales de la sintesis de cetales de glicerina para su uso como aditivos que mejoren las propiedades de flujo a baja temperatura de un biodiesel de aceite de palma. Se evaluo su produccion empleando catalizadores heterogeneos acidos del tipo resinas de poliestireno sulfonadas (Amberlyst 15, Dowex 50X2) y homogeneos (acido sulfurico y p-toluensulfonico). Se analizo el efecto del cetal en las propiedades de flujo a baja temperatura al mezclarse en diferentes proporciones con el biodiesel, evaluando el punto de nube y el punto de fluidez a cada mezcla. Mediante calorimetria diferencial de barrido se evaluo los puntos de cristalizacion de las mezclas del aditivo con el biodiesel y se comparo con el correspondiente para el biodiesel puro. Se encontro que con el empleo de catalizadores heterogeneos se pueden obtener conversiones por encima del 90% y la adicion de los cetales al biodiesel puede lograr disminuciones de hasta 6oC en el punto de nube y fluidez. Tambien, los termogramas de enfriamiento mostraron una disminucion efectiva en las temperaturas de cristalizacion.

Soporte de Nuevas Películas de TiO2 y TiO2/SiO2 sobre Gránulos de Poliéster para Aplicación en Fotocatálisis

Peliculas de TiO2 o TiO2/SiO2 fueron soportadas sobre granulos de poliester usando mecanismos de difusion y posterior tratamiento termico a 100oC. Se emplearon dos clases de geles. El primero fue preparado usando diferentes cantidades de TiO2, cloruro de metileno y silicona liquida. El segundo fue obtenido por medio del metodo sol-gel, empleado para producir una matriz de silice a partir de la hidrolisis el tetraetilo ortosilicato, en un medio organico de 2-propanol, en el cual se disperso el fotocatalizador. Los precursores de cada sistema fueron agregados en diferentes relaciones para determinar su influencia en la estabilidad, propiedades y fotoactividad de las peliculas. La actividad fotocatalitica fue evaluada en la fotodegradacion de metanol en fase gaseosa. Los resultados muestran la produccion de materiales con alta resistencia, funcionalidad y actividad asi como una fuerte relacion entre la actividad fotocatalitica con las propiedades fisicoquimicas.

Síntesis y caracterización de espumas flexibles de poliuretano obtenidas a partir de aceite de castor maleinizado

In this work, the synthesis of polyurethane flexible foam is realized with the experimental design Taguchi, using castor oil with and without maleinization. The kinetic reaction of oil esterification was monitored by estimating the number of acid groups (ASTM D4662 - 03), and the mechanical properties of the foam were studied, including density, tensile resistance, % elongation, resilience and hardness (Norm NTC 2019 Icontec). The influence of various synthesis parameters was investigated, namely amount and type of catalyst, molar ratio of castor oil (CO) - maleinizated castor oil (MACO), amount of water and surfactant used. The foams were analyzed using FTIR and scanning electron microscopy (SEM). The results showed first order kinetics with respect to the anhydride. The maleinizated castor oil (MACO) increased the mechanical resistance of the foam due to the greater interweaving by the incorporation of acid groups.

Efecto del Pretratamiento de Biomasa Maderera en el Rendimiento a Etanol

Wood samples from Pinus patula and Eucalyptus camaldulensis species were characterized according to procedures and protocols established by the National Renewable Energy Laboratory (USA), to determine their composition. Then, chips from these woods were pretreated by steam explosion, alkaline delignification, ammonia wet soaking, ozonolysis, dilute acid hydrolysis and organic solvent techniques, to condition the raw materials for the enzymatic hydrolysis step. This step was carried out with the commercial enzymatic pull Accellerase 1500 from Genecor followed by fermentation of the hydrolyzate using Saccharomyces cerevisiae Ethanol Red yeast in a simultaneous saccharification and fermentation configuration. The results of this step allowed selecting the better pretreatment method for woods. Alkaline delignification showed the best ethanol yields (2.17 g/L for Eucalyptus camaldulensis, and 2.61 g/L for Pinus patula).

Síntesis de espumas rígidas de poliuretano obtenidas a partir de aceite de castor y poliglicerol empleando calentamiento por microondas

In this work we showed the polyurethane rigid foams synthesis using a macropolyol synthesized from castor oil and polyglycerol. This process is optimized employing a response surface analysis and using a 32 factorial design. The factors evaluated were: amount of water and tartaric acid, where tartaric acid acts as crosslinking agent and catalyst; mechanical properties of foams were evaluated as bulk density (ASTM D1622-08), compressive strength (ASTM D1621), thermal conductivity (ASTM C177-04), and friability (ASTM C421-8); scanning electronic microscopic (SEM) and differential scanning calorimetry (DSC). The macropolyol was obtained from renewable sources by the transesterification of castor oil (CO) or maleinized castor oil (MACO) and polyglycerol (PG). The effect of microwaves on the reactions was evaluated, where there was a decrease in time. The monitoring and characterization of intermediate products were performed by quantifying the acid value by titration (ASTM D4662-03) and hydroxyl number (ASTM D4274-05).

Degradacion de naranja de metilo en un nuevo fotorreactor solar de placa plana con superficie corrugada

Methyl Orange degradation (MO) by heterogeneous photocatalysis using titanium dioxide Degussa P-25 and solar radiation in a photoreactor of corrugated plates was studied. Initial MO concentration, TiO2 amount and the catalyst disposition were used as experimental variables. MO degradation reached 99% and it adjusted to the model of Langmuir - Hinshelwood. The reaction followed an apparent firstorder kinetics with respect to the MO and it showed an increase in the rate constant when increasing the suspended catalyst amount and diminishing the initial MO concentration.

Producción de Diésel Renovable a partir de Aceite de Higuerilla mediante Catalizadores de Níquel-Molibdeno Soportados sobre Alúmina

espanolSe sintetizaron dos catalizadores tipo Ni-Mo soportados sobre y-Al2O3, con diferentes contenidos masicos de los metales activos, y su actividad catalitica en el proceso de desoxigenacion de aceite de higuerilla fue evaluada y comparada con el desempeno obtenido con un catalizador comercial. Previo a las reacciones de desoxigenacion, los catalizadores fueron reducidos y sulfurados con H2S producido in-situ. Los catalizadores fueron caracterizados mediante DRX, adsorcion-desorcion de N2 a 77 K, XRF y TPR. Las pruebas cataliticas fueron llevadas a cabo en un reactor de alta presion (Parr, 500 mL), operando en modo semi-batch. El mayor rendimiento masico hacia diesel renovable (C9-C24) fue del 82.9% y se obtuvo con el catalizador sintetizado que contiene 4.5% NiO y 20% MoO3, evaluado a 350°C, 90 bares y una concentracion del 10%. Ademas, este catalizador, bajo estas condiciones, presento una conversion del 100% y las selectividades mas altas hacia C17 (54.4%) y C18 (20.9%), asi como una menor selectividad a craqueados (0.83%). EnglishCatalysts of Ni-Mo type with different content of active species (Ni,Mo) were synthesized and supported over y-alumina and their catalytic activity in the deoxygenation process of castor oil was evaluated and compared with that obtained with a commercial catalyst. Prior to deoxygenation reactions, the catalysts were reduced and sulfurated with H2S produced in-situ. The catalysts were characterized by XRD, N2 adsorption-desorption at 77K, XRF and TPR. The catalytic tests were carried out in a high-pressure reactor (Parr, 500 mL), operating in semi-batch mode. It was found that the highest mass yield to renewable diesel (C9-C24) was 82.9%, obtained with the synthesized catalyst containing 4.5% NiO and 20% MoO3 operating at 350 °C, 90 bars and 10% catalyst concentration. Besides, this catalysts exhibited 100% conversion and the highest selectivities to C17 (54.4%) and C18 (20.9%), as well as the lowest selectivity to cracked products (0.83%).