Pablo J. Miguel

Influence of hydrocarbon chain length and zeolite structure on the catalyst activity and deactivation for n-alkanes cracking

Abstract Kinetic determinations of the cracking and catalytic decay of n-heptane, n-decane, n-dodecane and n-tetradecane have been carried out on USY, Beta and ZSM-5 zeolites by means of an experimental set which allows to take samples of products coming out from the reactor at very short time on stream. The influence of the zeolite properties on the catalytic activity and catalyst decay has been obtained. By studying the evolution of the rate constants with the number of carbon atoms in the n-alkanes it has been found that the existence of a PCP cracking mechanism would be consistent with the observed evolution.

Product selectivity effects during cracking of alkanes at very short and longer times on stream

Abstract Cracking of C 7 , C 10 , C 12 and C 14 n-alkanes, over USY, Beta and ZSM-5 zeolites was carried out in a reaction system which allows to obtain instantaneous conversions at very short times on stream. With this system the influence of operation variables, chain length of the paraffin fed, and catalyst structure on product selectivity was established. Positive and negative effects of catalyst decay on product selectivity were obtained, and this behaviour could be simulated by using a deactivation model in which the rate of deactivation depends on the product concentration. It was observed that olefin/paraffin, branched/normal paraffin, branched/normal olefin ratios and aromatic selectivities are affected by chain length, conversion level, and time on stream. Their evolution was explained by taking into account bimolecular reactions of hydrogen and hydride transfer, and the effect of deactivation at very short times on stream, similar to those in FCC units, could be determined. Furthermore, the catalyst structure showed an significant effect on space demanding reactions, such as bimolecular ones. The importance of that effect follows the order USY > Beta > ZSM-5 .

Isobaric vapor-liquid equilibrium of binary mixtures of 1-propanol + chlorobenzene and 2-propanol + chlorobenzene

Abstract Isobaric vapor-liquid equilibria were obtained for the system 1-propanol + chlorobenzene at 20 and 100 kPa and for the system 2-propanol + chlorobenzene at 100 kPa using a dynamic still. The experimental error in temperature was ±0.1 K, in pressure ±0.01 kPa and ±0.1 kPa for the experiments carried out at 20 and 100 kPa, respectively, and in the liquid and vapor mole fraction 0.001. The two systems satisfy the point-to-point thermodynamic consistency test. Both systems show a positive deviation from ideality. The data were well correlated with the Margules, Van Laar, Wilson, NRTL and UNIQUAC equations.

Vapor–liquid equilibrium of binary mixtures of trichloroethylene with 1-pentanol, 2-methyl-1-butanol and 3-methyl-1-butanol at 100 kPa

Abstract Isobaric vapor–liquid equilibria (VLE) have been obtained for the systems trichloroethylene+1-pentanol, trichloroethylene+2-methyl-1-butanol and trichloroethylene+3-methyl-1-butanol at 100 kPa using a dynamic still. The experimental error in temperature is ±0.1 K, in pressure ±0.1 kPa, and in the liquid and vapor mole fraction ±0.001. The three systems satisfy the point-to-point thermodynamic consistency test. All the systems show positive deviations from ideality. The data have been correlated with the Margules, van Laar, Wilson, NRTL and UNIQUAC equations.

Theta-1 zeolite catalyst for increasing the yield of propene when cracking olefins and its potential integration with an olefin metathesis unit

There is a need for on-purpose propene production technologies beyond energy-intensive steam cracking. Hexene is a compound with limited value that can be found in several streams in the refinery and can readily crack on zeolites at lower temperatures and shorter contact times than those used for cracking alkanes. Cracking over ZSM-5 zeolite yields high selectivity to light olefins. These results are improved by Theta-1 zeolite, which can yield a remarkable propene molar selectivity of 180% (90 wt%) at 90% conversion, close to the maximum thermodynamic yield. Moreover, crystal engineering allowed its TOF to increase by more than 50%. Based on these results we also identified some prospective applications of Theta-1 zeolite as a catalyst for an integrated process directed to maximize propene.

Vapor–liquid equilibrium of binary mixtures of chlorobenzene with 3-methyl-1-butanol, 3-methyl-2-butanol and 2-methyl-2-butanol, at 100 kPa

Abstract Isobaric vapor–liquid equilibria have been obtained for the systems 3-methyl-1-butanol+chlorobenzene, 3-methyl-2-butanol+chlorobenzene and 2-methyl-2-butanol+chlorobenzene at 100 kPa, using a dynamic still. The experimental error in temperature is ±0.1 K, in pressure ±0.1 kPa, and in the liquid and vapor mole fraction ±0.001. The three systems satisfy the point-to-point thermodynamic consistency test. All the systems show positive deviations from ideality. The data have been correlated with the Margules, Van Laar, Wilson, NRTL and UNIQUAC equations.