Simulation & Modeling
Mehrsa Emami; Farzin Hormozi; Hossein Abedini
Abstract
Bulk phase polymerization of propylene with a 4th generation of Ziegler-Natta catalyst was kinetically investigated by means of heat flow calorimetry. The assumptions and modifications on isothermal calorimetric method were demonstrated. Our calibration method showed that heat exchange with the reactor ...
Read More
Bulk phase polymerization of propylene with a 4th generation of Ziegler-Natta catalyst was kinetically investigated by means of heat flow calorimetry. The assumptions and modifications on isothermal calorimetric method were demonstrated. Our calibration method showed that heat exchange with the reactor cover plate is not constant over time. Therefore, the dynamic of cover plate temperature was considered in the calorimetric method. The polymerization rate profiles depending on hydrogen and external electron donor concentration have been investigated. Normalized polymerization profiles (Rp /Rpmax) are plotted and expressed as an exponential function of time. Effects of hydrogen and external electron donor (ED) concentration on Rpmax and polymerization rate were investigated as well. The results showed that by increasing hydrogen concentration, initial polymerization rate (Rpmax) increased. Hydrogen increased productivity by increasing the initial polymerization rate, while it had no negative effect on the rates of decay or its effect was small. The ED concentration was optimized so that the catalyst deactivation rate was at its lowest level. Also, changes in the ratio of activation to inactivation with ED concentration were examined, and a proportional change was observed.
Simulation & Modeling
Hafez Maghsoudi
Abstract
In this paper, the performances of potential zeolite membranes were estimated by the Maxwell-Stefan model and then they were placed in Robeson plot of propylene/propane separation. Additionally, the effects of feed pressure and the mole fraction of propylene in the feed on both the propylene ...
Read More
In this paper, the performances of potential zeolite membranes were estimated by the Maxwell-Stefan model and then they were placed in Robeson plot of propylene/propane separation. Additionally, the effects of feed pressure and the mole fraction of propylene in the feed on both the propylene permeabilities and membrane permselectivities were investigated. The results showed that zeolite membranes had better performances than carbon and polymer membranes. However, the performances of carbon membranes were better than those of zeolites 4A and ITQ-3. Also, among various zeolites studied, a DD3R zeolite membrane had the highest propylene permselectivity. According to the minimum requirement needed for membranes (i.e., a minimum selectivity of 35 and a permeability of 1 Barrer) for propylene/propane separation, it was found that the zeolite membranes of DD3R, SAPO-34, Si-CHA and ITQ-12 had this performance requirement. However, DD3R and SAPO-34 zeolite membranes were more preferred than the polymer, carbon and composite membranes due to their higher performances.
