Propane Dehydrogenation over In₂O₃–Ga₂O₃–Al₂O₃ Mixed Oxides

Abstract

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.

Catalytic Performance of In/HZSM‐5 for Coupling Propane with CO2 to Propylene

“…The conversion of propane gradually decreases with the increase of reaction time in the three cycles of experiments. It is due to In 3+ is reduced to In 0 (Figure B) led to the loss of catalyst active sites and In species are sintered . Catalyst activity could be recovered by the regeneration of 12% In/HZSM‐5 on the 550 °C by air calcination temperature for 5 h, indicating that the In 0 is oxidized to In 3+ (Figure B).…”

“…Catalyst activity could be recovered by the regeneration of 12% In/HZSM‐5 on the 550 °C by air calcination temperature for 5 h, indicating that the In 0 is oxidized to In 3+ (Figure B). In the indium‐based catalysts reported in the literature, the conversion of C 3 H 8 decreases about 5–7% during the reaction. In Figure , we can see that the conversion of C 3 H 8 has only decreases about 3%.…”

“…[b] The propane dehydrogenation, under 600 °C for 6 h, atmospheric pressure, C 3 H 6 : N 2 =1 : 19 and total flow rate of 20 mL/min. Data from . [c] The CO 2 hydrogenation, under 380 °C, 3.0 MPa, H 2 : CO 2 : N 2 =73: 24 : 3 and total flow rate of 150 mL/min.…”

“…It is an exothermic process and the required temperature is about 300–500 °C, which is lower than the dehydrogenation temperature of propane, but the required reaction pressure is higher than 3 MPa. Dehydrogenation of propane and hydrogenation of CO 2 has been studied by many scholars . As the dehydrogenation of propane to propylene can generate a great number of hydrogens and the hydrogenation of CO 2 to light olefins needs hydrogen greatly, a promising approach is the coupling of propane with CO 2 to produce propylene, which can not only use the hydrogen but also change the reaction balance of propane dehydrogenation to increase the yield of propylene.…”

“…Indium oxide and HZSM‐5 zeolite were used as a catalyst both in the dehydrogenation of propane and CO 2 hydrogenation . Indium oxide has a unique ability to selectively activate hydrogen, redox properties and a good ability to activate propane .…”