Catalytic decomposition reactors

A catalyst bed comprising:

• a structure defining a plurality of channels configured to receive flow of fluid to be chemically catalyzed, wherein the plurality of channels are oriented at least partially non-parallel to an overall flow direction of the flow from inputs of the plurality of channels to outputs of the plurality of channels, and
• wherein a catalyst is exposed at an exterior of the structure,
• wherein the plurality of channels have a plurality of first ports arrayed at a first plane and a plurality of second ports arrayed at a second plane, the plurality of first ports being connected to respective ones of the plurality of second ports by respective ones of the plurality of channels, such that a number of the plurality of first ports matches a number of the plurality of second ports, and
• wherein a number density of the plurality of first ports at the first plane is different from a number density of the plurality of second ports at the second plane.