Effect of Pressure on Ethane Dehydrogenation in MFI Zeolite Membrane Reactor

Using a membrane reactor (MR) for producing ethylene by ethane dehydrogenation (EDH) reaction is an effective process. Compared with packed bed reactors (PBR), the EDH MR effectively surpasses the equilibrium limit by timely removing H-2. A packed bed membrane reactor (PBMR) with a Pt/Al2O3 catalyst was used to investigate the effect of pressure on the EDH reaction. The EDH reaction was performed in the PBMR for the pressure and temperature range of 1-5 atm and 500-600 degrees C, respectively. With an increase in reaction temperature, the reaction rate increased which caused higher ethane conversion. Increasing the reaction pressure helped in enhancing H-2 permeation across the membrane, which significantly increased the ethane conversion. The equilibrium limit of ethane conversion was successfully surpassed by increasing temperature and reaction pressure in the PBMR. Ethane conversion and ethylene selectivity as high as 29% and 97% were obtained at 600 degrees C and 5 atm for PBMR while corresponding values were 7% and 75% for PBR. The timely removal of H-2 from the reaction side also helped in reducing methane formation as H-2 is required for the methanation to occur. In addition, a 1D plug flow model was developed, and the values for ethane conversion obtained from the model were validated with experimental results. The same model was used to evaluate the ethane conversion beyond the experimental conditions, showing ethane conversion >90% could be obtained.