455930 Experimental and Simulation Study of Ethanol Steam Reforming Reaction for Hydrogen Production in Large Scale Catalytic Membrane Reactor

Tuesday, November 15, 2016: 8:30 AM
Plaza B (Hilton San Francisco Union Square)
Rui Ma1, Bernardo Castro Dominguez1, Ivan Mardilovich2, Anthony G. Dixon3 and Yi Hua Ma4, (1)Chemical Engineeirng, Worcester Polytechnic Institute, Worcester, MA, (2)Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA, (3)Department of Chemical Engineering, Worcester Polytechnic Institute, Worcester, MA, (4)Worcester Polytechnique Institute, Worcester, MA

Experimental and simulation study of ethanol steam reforming reaction for hydrogen production in large scale catalytic membrane reactor

Rui Ma, Bernardo Castro-Dominguez, Ivan P. Mardilovich, Anthony G. Dixon, Yi Hua Ma

Center for Inorganic Membrane Studies, Department of Chemical Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01609, USA.

            Production of hydrogen from ethanol steam reforming (ESR) has attracted more interest due to the massive application of hydrogen and carbon neutral property of bio-ethanol.  In hydrogen production, the process intensification concept has been applied to ESR by conducting the reaction in a catalytic membrane reactor (CMR) in order to generate and separate pure hydrogen in the same unit simultaneously. Since the product is being removed during the reaction, the conversion is improved.

          In the present study, ESR was carried out in a large scale CMR with a 150 cm2 membrane surface area. The process was investigated both experimentally and with Computational Fluid Dynamics (CFD) simulation. A defect-free membrane was prepared as Pd/Au/Pd/Au and placed in the center of a double screen annular cage while a nickel-based commercial catalyst (HiFUEL R110) was loaded between the double screens surrounding the membrane as shown in Figure 1, thus the catalyst particles were not in direct contact with the membrane surface. The reaction was performed under different operating conditions: liquid hourly space velocity (LHSV), operating pressure and temperature as well as steam to ethanol (S/E) ratio. Under 300 hours of operation, 100% conversion of ethanol was achieved under all conditions; H2 with 99.9% purity was produced with the rate of 0.38 g/h at LHSV= 3.77 h-1, P=5 bar, T= 500 ¡C and S/E= 5. It was shown that the process is enhanced by high pressure, high S/E ratio and high temperature. The effect of each condition is discussed in detail in this work.   

           Simulation models were developed in 1-D and 2-D utilizing Polymath and COMSOL Multiphysics respectively. The kinetics used in the model were validated against experimental outcomes from previous publications using the 1-D model. In the 2-D model, the hydrogen permeation process was simulated as a flux term on both shell side (retentate) and tube side (permeate) applying SievertsÕ law:

-n∙Ni=PH2[PH2shell-PH2tube]

(1)

in which PH2shell and PH2tube represent H2 partial pressure at the retentate side and permeate side respectively.

For the 2-D simulation, the equation of motion and the species continuity equations were solved simultaneously using a finite element method. The effect of the catalytic bed was considered by implementing the Darcy-Forchheimer law to describe the extra resistance to the flow, in which Ergun equation was used to describe the pressure drop in the porous medium.  The simulation results were compared with experimental data and showed an accuracy of 84% for 1-D simulation and 91% for 2-D simulation.

            Applying the simulation model, the benefits of process intensification were observed by comparing the H2 production rate from ESR in a traditional packed bed reactor (PBR) and in the CMR. While operating the reaction at higher temperatures and higher pressures, an improvement of up to 122% of H2 generation in CMR was shown.

Figure 1. Representation of ESR carried out in a CMR.


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