Dissertação
Produção de eteno a partir de etanol utilizando aluminas
Fecha
2012-09-24Registro en:
ROS, Simoní da. ETHYLENE PRODUCTION FROM ETHANOL USING ALUMINAS. 2012. 138 f. Dissertação (Mestrado em Engenharia) - Universidade Federal de Santa Maria, Santa Maria, 2012.
Autor
Ros, Simoní da
Institución
Resumen
Calcination variables, temperature, time and heating rate, used in obtaining different
transition aluminas were simultaneously investigated using statistical experimental design.
Empirical models correlating catalyst final properties and calcination conditions were
employed. It was found that all calcination variables play fundamental roles on acidity of
alumina catalyst. Furthermore, interaction effects among these variables and non-linear
effects also are of fundamental importance for the final properties catalyst. Therefore, the use
of simultaneous variation of calcination conditions through experimental design is of great
importance in detecting such interactions. It was observed that the use of high heating rates
favor the formation of pore with larger diameters and with high pore volume and, for short
calcination time, high heating rate also contributes to the formation of higher concentration of
acid sites. The acid sites characterization of transition aluminas were performed by
temperature programmed desorption of ammonia (NH3-DTP), which showed that there are
two distinct acid sites on the surface these materials. The desorption dates were adjusted by a
model in which the catalyst bed was considered as single continuously stirred tank reactor and
the intrinsic kinetic was chosen to be of first order for adsorption and desorption. The ethanol
conversion was higher for the alumina with higher acid sites concentration, suggesting a
relationship between the activity of the alumina for the ethanol conversion and its acidity. The
selectivity for the ethylene formation also was higher for the more acid aluminas, while the
selectivity to ether presented opposite behavior. Therefore, a successful control of all
calcination conditions can be an effective method to adjust the final physical and chemical
properties of transition alumina catalyst, aiming the highest yield of ethylene from ethanol
dehydration.