Reactor

A reactor in which a catalyst to accelerate reaction of a reactant is allowed to act on a reaction fluid having a reactant, the reactor comprising:

• a partition that defines a layered space between a plurality of heat transfer walls into a plurality of reaction flow passages in a parallel form, through which the reaction fluid flows;
• and
• a plurality of catalyst structures, each having the catalyst and being respectively loaded in each of the plurality of reaction flow passages;
• wherein each of the plurality of catalyst structures includes a main body made of a thin plate material on which the catalyst is supported, the partition has a communicating portion allowing the plurality of reaction flow passages to communicate with each other, and the communicating portion is arranged in a location closer to inlet side branch points than to outlet side branch points of the reaction flow passages within a range where the reaction fluid branches to flow, and
• wherein the main body of each of the plurality of catalyst structures divides the reaction flow passage along the flow direction of the reaction fluid and defines a plurality of partial flow passages in parallel, and the main body has a communicating portion allowing the plurality of partial flow passages to communicate with each other in correspondence with the communicating portion of the partition.