(172e) Modified Nano-Size ?-Al2O3 Supported Ga2O3 with Improved Performance for Non-Oxidative Propane Dehydrogenation
AIChE Annual Meeting
Monday, October 29, 2018 - 1:50pm to 2:10pm
Gallium oxide is one of the active catalyst for propane dehydrogenation reaction and it has been investigated on various supports such as Al2O3, SiO2, CeO2, TiO2 & ZrO2. Among all the support Ga2O3/Al2O3 has shown highest initial activity. However it suffers from deactivation faster as compared to other support. This work aims at improving the stability as well as performance of Ga2O3 on Ï-Al2O3 as a support by improving its properties with the help of synthesis method. Here, Ï-Al2O3 was synthesized using organic acid as a structure directing agent followed by hydrothermal at high temperature. Ga2O3 was deposited using wetness impregnation method. The catalytic performance was compared with Ga2O3 on commercialized Ï-Al2O3. The activity of Ga2O3 on nano-size plate like Ï-Al2O3 was higher as compared to commercial alumina. The conversion for Ga/modified Ï-Al2O3 was maintained at around 32 % for 7 hours of operation as compared to Ga/commercial Ï-Al2O3 whose conversion reached around 20 % for the same operating time and higher selectivity of above 90% was obtained.The coke deposition after 7 hours are 3.6 wt% and 7.5 wt% for Ga on modified and commercial Ï-Al2O3 , respectively. Different phases of Ï-Al2O3 and peak broadening of modified Ï-Al2O3 was observed from XRD. In TPR analysis , nano-size modified Ï- Al2O3 well dispersed Ga in the temperature range of 400-600 ÂºC; main peak being shifted to higher temperature elucidating the higher metal and support interaction. Further, pyridine DRIFTS analysis was carried out at different temperature In order to investigate the presence of Lewis acidic centers and Bronsted acidic centers. An additional shoulder-like peak at around 1622 cm-1 was observed for Ga /modified Ï- Al2O3 which belongs to the most stable Lewis acidic centers and this peak was absent in Ga/ commercial Ï- Al2O3. There was no band at 1622 cm-1 present in the pure support indicating the unique interaction between metal oxide and support after the addition of gallium. XPS was done to investigate the interaction between Ga and Ï-Al2O3 by analyzing the change in binding energy of Ga in 3d orbital. From all these characterizations, supporting the performance of the catalyst, it can be concluded that modification of alumina surface with hydrothermal method and addition of organic acid helps to enhance the surface acidic centers by introducing more hydroxyl groups leading to the enhanced performance and stability.