Perfectionnement aux procédés de préparation d'eau lourde par échange isotopique monotherme NH -H

In a process for enriching NH3 in deuterium by single temperature isotopic exchange in at least one reactor between liquid NH3 containing dissolved catalyst, e.g. amide of K, Cs, or Rb, and H2, at least one catalyst recycling loop is associated with at least one reactor in which the NH3 leaving the reactor is either partially evaporated and subjected to isotopic exchange with deuterium poor ammonia synthesis gas, or completely evaporated, and the resulting concentrated catalyst solution, or dry catalyst, is reinjected into the NH3 fed to the reactor. NH3 and NH3 synthesis gas are contacted in exchange towers 1, 2 which may be towers with plates or filling, or assemblies of such towers. Synthesis gas (H2+N2) is fed in at 5 (Figs. 3, 4) and synthesis gas is converted to NH3 in 4 whence D-poor NH3 is withdrawn at 7. Liquid NH3 from 4 passes through 1, 2 to evaporator 8, whence evaporated NH3 passes to 3 for conversion to synthesis gas, which returns to reactors 2, 1 and D-enriched NH3 is withdrawn at 6. In Fig. 3 concentrated catalyst solution from 8 is passed in isotope exchange with synthesis gas from reactor 1 in column 10, and returned to the NH3 feed at 9, while the synthesis gas is returned to reactor 1 at a point of similar D concentration. In Fig. 4 the NH3 and catalyst from 2 is completely evaporated in 8 and dried catalyst returned to the NH3 at 9. In alternative arrangements, Figs. 5, 6, 7 (not shown) two reactors are provided each of which has a separate recycle loop as described in Figs. 3 or 4, or one has a loop of the type of Fig. 3 and the other has that of Fig. 4. Specification 807,803 is referred to.