As we move toward a hydrogen-based energy economy for use in fuel cells, using the latter...

As we move toward a hydrogen-based energy economy for use in fuel cells, using the latter to operate appliances ranging from computers to automobiles is rapidly becoming a reality. In the immediate future, fuel cells will use hydrogen to produce electricity, which some have said will lead to a hydrogen-based economy instead of a petroleum-based economy. A large component in the processing train for fuel cells is the water gas shift membrane reactor. (M. Gummala, N. Gupla, B. Olsomer, and Z. Dardas, Paper I03c, 2003, AIChE National Meeting, New Orleans, LA.)

Here CO and water are fed to the membrane reactor containing the catalyst. Hydrogen can diffuse out (he sides of the membrane while CO, H20, and CO2 cannot. Based on the following information, plot the concentrations and molar flow rates of each of the reacting species down the length of the membrane reactor. Assume the following: The volumetric feed is 10 dnvVmin at 10 atm, and the feed is equimolar in CO and water vapor with CT0 = 0.4 mol/dm3. The equilibrium constant is Kc = 1.44. The specific reaction rate constant, k, is 1.37 dm6/mol kg cat ■ min, and the mass transfer coefficient for hydrogen, kH= 0.1 dmVkg cat ■ min. What is the reactor volume necessary to achieve 85% conversion of CO? Compare with a PFR. For that same reactor volume, what would be the conversion if the feed rate were doubled?