Hydrogen prodn. by decomposing water - in chemo-thermal cyclic process comprising splitting and reconstructing ammonium iodide

摘要

Hydrogen is prepd. by decomposing H2O, with inorg. ammonium or alkali(ne earth) metal salts used as reaction aids, by a chemo-thermal cyclic process comprising =3 stages. In one stage NH4I is split, the resulting HI is decomposed into H2 and I2 in a further stage, NH4I and a metal bicarbonate are formed with participation of NH3, CO2, H2O and a metal iodide, the metal bicarbonate is converted into the corresp. metal carbonate, this is reacted with iodine and the metal iodide is reconstructed whilst oxygen is collected as a by-prod. and CO2 is opt. recycled. Iodine is removed from the gas mixt. with aid of a liquid or solid substance, pref. an alkali(ne earth) metal halide. The metal iodide is pref. NaI or KI or a mixt. of alkali and/or alkaline earth metal iodides, capable of forming mixed bicarbonates barely-sol. in water. This process can be carried out with the use of NH4Cl or NH4Br, instead of NH4I. This process is based on reactions in aq. solns. pref. at 40-120, esp. 40-60 degrees C, the process can be carried out at normal press. pref., however, increased pressures are applied (=40 atmos.). Thus, the technology is simplified and the economy of the process is good.