Steam methane reformer hydrogen generation systems

A steam methane reformer (SMR) system comprising:

• an outer tube, wherein a first end of the outer tube is closed;
• an inner tube disposed in the outer tube, wherein a first end of the inner tube is open, wherein a flow channel is defined within the inner tube and an annular space is defined between the outer tube and the inner tube, the flow channel being in fluid communication with the annular space;
• a catalytic foam disposed in the annular space between the outer tube and the inner tube, the catalytic foam comprising a catalyst, an upstream end of the catalytic foam disposed at a first distance from the first end of the outer tube;
• an outer heat exchange foam disposed in the annular space between the outer tube and the inner tube, an upstream end of the outer heat exchange foam disposed at a second distance from the first end of the outer tube, in which the second distance is less than the first distance;
• and
• an inner heat exchange foam disposed in the flow channel defined within the inner tube, an upstream end of the inner heat exchange foam disposed at a third distance from the first end of the outer tube, in which the third distance is greater than the second distance and less than the first distance,
• wherein the outer heat exchange foam has a length between 4 inches and the first distance.