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The catalytic transformation of glycerol to value-added compounds was investigated over bimetallic Ni-Cu/y-Al2 O3 catalysts with Ni/Cu atomic ratios of 8/1, 4/1, 2/1, 1/1, 1/2, 1/4, and 1/8. XPS analysis revealed that the surface composition of the catalyst exhibited progressive enrichment of Cu as its content in the catalyst increased. H2 -chemisorption indicated that the total number of exposed Ni atoms decreased as the Cu content increased. As a result, deep hydrogenolysis to produce CH4 was inhibited by the addition of Cu to the Ni catalyst, yielding higher selectivity toward the dehydration products of glycerol such as hydroxyacetone.FTIR spectra of adsorbed CO reveal that Cu asserts both geometric and electronic effects on the adsorption properties of Ni. The geometrical effect is visualized by the progressive disappearance of the bridge-bound adsorbed CO on metallic Ni by the incorporation of Cu. This suggests that the deep hydrogenolysis of glycerol to CH4 formation requires an ensemble of adjacent active Ni atoms. The electronic effect of Cu on Ni is indicated by the red shift of the IR peak of adsorbed CO as the Cu content increases. The electronic interaction between Cu and Ni species was also substantiated by XANES results. HTREM revealed metal particles very well distributed on the support with particle size of 1.5 to 5 nm. The Ni-Cu samples were not a total intermetallic alloys..

The catalyst-free transesterification of castor oil under supercritical conditions, using methanol, was studied in this research to determine the molar ratio (methanol:castor oil) and reaction time that produced the biodiesel with the highest conversion by using a 10 L stainless steel batch reactor. The experiments were carried out with 30:1, 40:1, 50:1 and 60:1 molar ratios and reaction times of 5 min, 15 min, 25 min and 35 min under the critical temperature and pressure values according to the molar ratio tested. The reaction conversion was monitored by 1 H NMR spectroscopy. The biodiesel was characterized in order to evaluate its accordance to the ASTM D6751 specification and to plot the thermogravimetric and calorimetric profiles of the biodiesel with the highest conversion obtained by TGA and DSC analysis. A regression model was obtained as a reference to calculate the conversion under the studied range of molar ratios and reaction times in future experiments with a coefficient of determination of 95,22% and a standard error of ±1,37% from the observed conversion.

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In this paper, the performance of a gas/oil heat recovery unit is assessed experimentally and by the development of an Aspen model and artificial neural networks. The heat recovery unit is a cross-flow heat exchanger used to recover the residual heat of the exhaust gases coming from a microturbine to drive an absorption chiller. The test facility consists mainly of a microturbine, a heat recovery unit, and an air-cooled absorption chiller. The experiments were conducted at partial power loads and different thermal oil mass flows. Regarding the models, the Aspen model depends on inlet conditions, the mechanical description of the heat recovery unit, and the fluids thermophysical properties, whereas the ANN model consists of 3 trained artificial neurons, 4 inputs (inlet flows and temperatures), and 2 outputs (thermal load and overall heat transfer coefficient). The experimental tests show that the recovery unit recovers from 18.8 kW to 8.1 kW when the microturbine power output is varied from 23 kWe to 4 kWe. Results also show that the overall heat transfer coefficient ranges between 243 W.m −2 .K −1 and 89 W.m −2 .K −1 , while they evidence that the overall heat transfer resistance is controlled by the exhaust gases heat transfer resistance. Furthermore, simulation results show that the Aspen model predicts the heat recovery unit thermal load and overall heat transfer coefficient with average relative differences of 0.93% and 11.27%, respectively, to the experiments. The ANN model evidences average relative differences of 0.51% and 3.48% for the thermal load and overall heat transfer coefficient, respectively.

En esta investigación se estudió el efecto del tipo de catalizador, la temperatura de reacción y la relación de catalizador/parafinas en la conversión de parafinas desecho de la pirólisis de plásticos, a través de craqueo catalítico. Se seleccionaron los catalizadores Zeolita Y y Zeolita ZSM-5, las relaciones catalizador/parafina de 0.4:1 y 0.20:1 en peso, y las temperaturas de reacción de 440 ˚C y 400 ˚C. La reacción de craqueo de las parafinas se llevó a cabo en un reactor de lecho fijo. Por medio de análisis estadístico se determinó que el tipo de catalizador presenta el efecto más significativo al obtener un rendimiento promedio de 27.43 % utilizando el catalizador Zeolita ZSM-5 en contraste con el 13.10 % obtenido con la Zeolita Y. Se determinó que se obtiene 1.2 % más de rendimiento al utilizar la temperatura de 400 ˚C respecto a la de 440 °C. El factor relación catalizador/parafina no afecta de manera significativa el rendimiento. Según los análisis por cromatografía de gases, se esperaría que de este producto líquido obtenido se puedan obtener productos similares al diésel, combustible de aviación Jet A-1 y gasolina regular.