Solar thermochemical reactor and methods of manufacture and use thereof

A solar reactor comprising:

• a reactor member;
• an aperture for receiving solar radiation, the aperture being disposed in a plane on a wall of the reactor member, where the plane is oriented at any angle other than parallel relative to the centerline of the reactor member;
• a plurality of absorber tubes, wherein the absorber tubes are oriented such that their respective centerlines are at an angle other than 90° relative to the centerline of the reactor member;
• and wherein the aperture has a hydraulic diameter that is from 0.2 to 4 times a hydraulic diameter of at least one absorber tube in the plurality of absorber tubes;
• and
• a reactive material, the reactive material being disposed in the plurality of absorber tubes, and the reactive material consists of a first mixture of first particles and second particles, wherein the first particle consists only of manganese dioxide (MnO2) and the second particle consists only of magnesium oxide.