Ignacio Julián

Pd-Ag Membrane Coupled to a Two-Zone Fluidized Bed Reactor (TZFBR) for Propane Dehydrogenation on a Pt-Sn/MgAl2O4 Catalyst

Several reactor configurations have been tested for catalytic propane dehydrogenation employing Pt-Sn/MgAl2O4 as a catalyst. Pd-Ag alloy membranes coupled to the multifunctional Two-Zone Fluidized Bed Reactor (TZFBR) provide an improvement in propane conversion by hydrogen removal from the reaction bed through the inorganic membrane in addition to in situ catalyst regeneration. Twofold process intensification is thereby achieved when compared to the use of traditional fluidized bed reactors (FBR), where coke formation and thermodynamic equilibrium represent important process limitations. Experiments were carried out at 500–575 °C and with catalyst mass to molar flow of fed propane ratios between 15.1 and 35.2 g min mmol−1, employing three different reactor configurations: FBR, TZFBR and TZFBR + Membrane (TZFBR + MB). The results in the FBR showed catalyst deactivation, which was faster at high temperatures. In contrast, by employing the TZFBR with the optimum regenerative agent flow (diluted oxygen), the process activity was sustained throughout the time on stream. The TZFBR + MB showed promising results in catalytic propane dehydrogenation, displacing the reaction towards higher propylene production and giving the best results among the different reactor configurations studied. Furthermore, the results obtained in this study were better than those reported on conventional reactors.

Microwave-Assisted Catalytic Combustion for the Efficient Continuous Cleaning of VOC-Containing Air Streams

A microwave-heated adsorbent-reactor system has been used for the continuous cleaning of air streams containing n-hexane at low concentrations. Both, a single catalytic bed (PtY zeolite) and a double (adsorptive DAY zeolite + catalytic PtY zeolite) fixed-bed reactor configurations were studied under dry and humid conditions. The zeolites were selectively heated by short periodic microwave pulses that caused the desorption of n-hexane and its subsequent catalytic combustion. The double bed configuration was attractive because it allowed nearly the same performance with only half of the catalyst load. The operation was especially efficient under realistic humid gas conditions that favored more intense microwave absorption, producing a faster heating of the adsorptive and catalytic beds. Under these conditions, continuous gas cleaning could be achieved with short (3 min, 30 W) microwave heating pulses every 5 min.