278040 Ethane Oxidative Dehydrogenation Over Vox/Al2O3 Catalyst in a Fluidized Bed Reactor Under Oxygen-Free Conditions
Ethane Oxidative Dehydrogenation over γ-Al2O3-Supported Vanadium Oxide Catalyst in a Fluidized-Bed Reactor
Sameer A. Al-Ghamdi (1,2) , Hugo I. de Lasa(1)*, M. M. Hossain (3) and Mara Volpe (4)
1. Chemical Reactor Engineering Centre,University of Western Ontario, London, Ontario, (Canada) *email@example.com
2. Research & Development Center, Saudi Aramco Oil Compamy, (Saudi Arabia)
3. Department of Chemical Engineering, King Fahd University of Petroleum & Minerals, Saudi Arabia
4. Chemical Engineering Department, PLAPIQUI-(UNS-CONICET), (Argentina)
The main objectives of this study are: to develop reactivity tests for ethane oxidative dehydrogenation (ODH) on a 7.5 wt. % VOx/γ-Al2O3 catalyst under oxygen-free conditions, to elucidate the mechanistic reaction steps involved in the catalytic ODH of ethane and to establish a heterogeneous kinetic model that describes ethane ODH on the prepared catalyst.
Materials and Methods
The catalyst was prepared by wet impregnation method with Gamma form of alumina as support and vanadium III acetyl-acetonate V (AcAc)3 as precursor. Reaction experiments were developed in a novel Chemical Reactor Engineering Center (CREC) mini-fluidized bed Riser Simulator. Reaction runs were carried out in the CREC fluidized bed riser reactor at reaction temperatures between 550-600 oC and under atmospheric pressure and oxygen free atmosphere. A number of physicochemical techniques were used to characterize the prepared catalyst.
Results and Discussion
The prepared catalyst showed very stable reduction behavior during consecutive TPR cycles with 550 oC as reduction temperature (Figure-1). Given the results obtained from experiments in oxygen-free environment, it appears that lattice oxygen is involved in the catalytic ODH reaction where prepared catalyst displayed promising ethane conversions (6.47-27.64%), ethylene selectivity (57.62-84.51%) and catalyst stability during ethane ODH at 550-600 0C (Figure-2). A rate equation is developed based on a lumped model using Langmuir-Hinshelwood kinetics. The proposed kinetic model satisfactorily predicts the ODH reaction of ethane under the selected reaction conditions.
Figure (1): Successive TPR profiles for VOx/γ-Al2O3 catalyst. Pre-treatment: calcination at 773 K.
Figure (2): Temperature dependence of C2H6 conversion and C2H4 selectivity (reaction time= 30 sec, C2H6 injected= 20 ml, catalyst loaded = 0.76g).
The development of a very stable and selective catalyst for ethane ODH is a major challenge that has to be overcome to have available a viable alternative and less energy demanding ODH process for olefin production. These new process will likely involve fluidized beds and as a result a selective fluidizable catalyst is the key for successful implementation of future ODH processes.
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