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A series of ternary mixed metal oxides containing Group III A elements (In, Ga, Al) is prepared by means of an alcoholic co-precipitation method. Specifically, oxide catalysts with a molar composition of In/Ga/Al=5:15:80, 10:10:80, and 15:5:80 are reported. The chemical composition, redox properties, and catalyst structures are fully characterized, with the results suggesting that the indium, gallium, and aluminum moieties are well-dispersed in the catalysts. The catalysts are evaluated for propane dehydrogenation (PDH) at 570 and 600 °C under 1 atm total pressure. The most effective catalyst with a composition of In/Ga/Al=5:15:80 provides 17 % conversion and approximately 86 % C3H6 selectivity with an initial activity of 4.6 mmol h−1 gcat−1 and 24.1 μmol h−1 m−2. The intrinsic activity on an active metal (i.e. indium and gallium) basis is approximately 3 times that of the In2O3-Ga2O3 family and approximately 3-9 times that of the In2O3-Al2O3 family. The catalyst deactivates with time on stream, and regeneration tests show that removal of surface coke and recovery of an In2O3 state helps to regain the initial activity, whereas reducing In2O3 domains into In0 does not allow for recovery of the performance. Raman analysis of the carbonaceous species deposited on the catalyst indicates catalysts with higher gallium content give more graphitic carbon, which correlates with higher C3H6 selectivity, whereas catalysts with more disordered coke are associated with lower selectivity. However, higher gallium content causes more coke formation, which leads to faster deactivation. This initial study of this family of mixed oxides suggests that an ideal In/Ga ratio may exist whereby catalyst properties may be optimized. [ABSTRACT FROM AUTHOR]

A modeling-based approach is presented to understand physically realistic and technologically interesting material properties and operating configurations of packed-bed membrane reactors (PBMRs) for propane dehydrogenation (PDH). PBMRs composed of microporous or mesoporous membranes combined with a PDH catalyst are considered. The influence of reaction and membrane transport parameters, as well as operating parameters such as sweep flow and catalyst placement, are investigated to determine desired 'operating windows' for isothermal and nonisothermal operation. Higher Damköhler (Da) and lower Péclet (Pe) numbers are generally helpful, but are much more beneficial with highly H2-selective membranes rather than higher-flux, lower-selectivity membranes. H2-selective membranes show a plateau region of conversion that can be overcome by a large sweep flow or countercurrent operation. The latter shows a complex trade-off between kinetics and permeation, and is effective only in a limited window. H2-selective PBMRs will greatly benefit from the fabrication of thin (∼1 µm or less) membranes. © 2014 American Institute of Chemical Engineers AIChE J, 61: 922-935, 2015 [ABSTRACT FROM AUTHOR]