NAMS 2002 Workshop - ICOM 2008

Membrane Modeling II - Gas Separation – 5
Tuesday July 15, 4:30 PM-5:00 PM, O’ahu/Waialua
Modeling and Performance Assessment of Pd- and Pd/Alloy-based
Catalytic Membrane Reactors for Hydrogen Production
M. Ayturk (Speaker), Worcester Polytechnic Institute, Worchester, Massachusetts, USA
N. Kazantzis, Worcester Polytechnic Institute, Worchester, Massachusetts, USA
Y. Ma, Worcester Polytechnic Institute, Worchester, Massachusetts, USA - yhma@wpi.edu
As global competition for oil supplies steadily intensifies, transforming today’s oil
dominated energy and transportation system to one running on hydrogen,
represents one of the most daunting challenges. The production of hydrogen via
natural gas steam reforming (MSR) and/or water-gas shift (WGS) reaction of the
coal-derived syngas in Pd- and sulfur tolerant Pd/Alloy-based catalytic
membrane reactors (CMRs) is an attractive technology which generates further
interest primarily due to its great potential for process intensification. Motivated
by the above considerations, the main objective of the present study is to
develop a systematic and comprehensive modeling framework for the
assessment of the impact of operating conditions on Pd-based CMR
performance, as well as appropriately define indicators representing quantitative
criteria for the attainment of key process intensification objectives (efficiencies in
the use of material and energy resources, cost and “waste management” for a
given production capacity target).
An isothermal mathematical steady-state model of an industrial size CMR for the
MSR, WGS and methanation reactions was developed and a comparative
performance assessment of the CMR versus a conventional packed bed reactor
(PBR) was conducted. The temperature dependence of the reaction rate
parameters, equilibrium and adsorption constants and the intrinsic reaction
kinetics for the MSR and WGS reactions on a supported Ni catalyst were
adopted from the detailed experimental study conducted by Xu and Froment.
Based on the available literature data, an average hydrogen permeability for the
pure-Pd films has been determined via linear regression analysis and used to
estimate the rate of hydrogen removal in the CMR model. The Matlab® software
was utilized to numerically integrate the set of process model equations via a 4th
order Runga-Kutta algorithm. In particular, the model is structurally comprised of
the requisite set of independent mass balance equations that describe the
steady-state profiles of product distribution and total methane conversion along
the lengths of both the tubular CMR as well as the PBR.
Validation of the CMR model was accomplished by simulating both the Pd-based
CMR and the conventional PBR conditions reported in the literature. A detailed
literature benchmarking showed that the models developed in this study