Abstract: A multi-phase thermochemical circulating process for producing hydrogen and oxygen from water is described, using the system of iron and chlorine compounds. Hydrogen is released by the reaction of iron(II)-oxide with water vapor and the oxygen by the reaction of chlorine with water vapor, iron(II)-oxide or iron (II, III)-oxide. Intermediately-formed iron (II)-chloride is hydrolyzed with water vapor to iron(II)-oxide in a multi-stage reaction at a gradually raised temperature, whereby in the hydrolysis the formation of metallic iron or of iron(II, III)-oxide is avoided.

Abstract: A process is provided for manufacturing iron(II)chloride from iron(III)chloride. Iron(III)chloride is introduced in dimeric form into a reactor or it is vaporized into the dimeric form in the reactor. The dimeric iron(III)chloride vapor rises into the upper part of the reactor where it is completely condensed to the monomeric form. The condensed monomeric iron(III)chloride falls within the reactor to the lower part of the reactor where it is again vaporized. From this reacting circulating system of iron(III)chloride, solid iron(II)chloride is left in the lower part of the reactor. The solid iron(II)chloride is then removed from the reactor.

Abstract: Decomposition of water to hydrogen and oxygen with the aid of a thermochemical cyclic process based upon the iron/chlorine system by reduction of FeCl.sub.2 in the presence of H.sub.2 to Fe, oxidation of the Fe with steam to Fe.sub.3 O.sub.4, treatment of the hot Fe.sub.3 O.sub.4 with steam and chlorine to obtain oxygen, conversion of themixture of iron oxides so obtained with hydrogen chloride to FeCl.sub.2 and recycling of the FeCl.sub.2 to the reduction stage, wherein a part of the heat required for the process is supplied by heating the hydrogen and steam in indirect heat exchange with a hot coolant from a high temperature nuclear reactor. The conversion of the iron oxides to FeCl.sub.2 is carried out via the intermediate stage of dimeric FeCl.sub.3 and it is thus possible to convey the solid reaction products by free fall through the reaction zones.