TECHNOLOGY FOCUS - CHEMICAL ENGINEERING - Preferred Components: The steam reforming catalyst is positioned exterior of the fluid conduit(s) and the passage extends interior of the fluid conduit(s). Alternatively, the stream reforming catalyst is positioned interior of the fluid conduit(s) and the passage extends exterior of the fluid conduit(s). The combustion region includes a burner. The fuel processor is in combination with a fuel cell stack adapted to receive at least a portion of the product hydrogen stream and to produce an electric current. The combustion region is adapted to receive air from supporting combustion from the fuel cell stack. A housing contains at least the hydrogen-producing region and solid insulating material. The hydrogen-producing region is a first hydrogen-producing region. The fuel processor further includes a second hydrogen-producing region. The separation assembly is in fluid communication with the first hydrogen-producing region and the second hydrogen-producing region. The first hydrogen-producing region is spaced apart from the second hydrogen-producing region. It is fluidly connected to the second hydrogen-producing region through conduit(s). The fuel processor further includes a polishing catalyst bed that includes a methanation catalyst. The polishing catalyst bed is in fluid communication with the separation assembly and adapted to receive the permeate stream and to produce the product hydrogen stream from the permeate stream. The separation assembly may include an enclosure (12) that defines an internal compartment (18) in which the hydrogen-selective membrane is housed. The enclosure includes a pair of opposed end plates. At least one of the end plates includes an exterior cavity that extends into the end plate and toward the internal compartment. The separation assembly includes membrane envelope(s) formed from a pair of hydrogen-selective membranes.    TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The fuel stream at least partially comprises the byproduct stream containing greater than or equal to20 wt.% hydrogen gas.Preferred Materials: The hydrogen-selective membrane is formed from palladium and/or palladium alloy. The palladium alloy comprises palladium and copper and further includes a secondary component consisting of less than 100 ppm carbon.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Product: The polishing catalyst bed catalytically produces methane from at least a portion of any carbon dioxide and carbon monoxide in the permeate stream.