15 Steam reforming reaction of methanol with a membrane reactor catalysis-spillover-membrane

Abstract

As hydrogen energy is receiving greater attention in the dawn of this new century, the complexity of hydrogen supply becomes an urgent concern for resolution. Hydrogen supply involves production, shipping and storage; cost estimates are presented to show the necessity of utilizing onsite hydrogen generation in the future hydrogen energy system. The methanol steam reforming reaction with a copper catalyst in the presence of a palladium membrane as a means of serving as an onsite hydrogen supply system was studied. In the course of this study our kinetic study indicated an unexpected rate enhancement of the forward reaction. This is attributed to hydrogen spillover from the catalyst allowing the direct transport of the newly produced atomic hydrogen to the membrane surface. This phenomenon is further supported by the chemisorption-permeance of hydrogen through a palladium membrane in the presence of a copper catalyst. The hydrogen permeance through the membrane is increased by the presence of a copper/zinc catalyst on the membrane surface. This indicates that hydrogen spillover or reverse spillover is playing the role of a kinetic bridge connecting the catalyst site and membrane surface. This shortcut bridge enables the newly produced hydrogen atom to diffuse to the membrane surface for permeation out of the system and the active catalyst site to turn over faster for a new run of chemisorption-reaction.