Depleted uranium catalysts for chlorine production

This study demonstrates depleted uranium as a remarkable heterogeneous catalyst for the oxidation of HCl to Cl sub(2). This reaction comprises a sustainable approach to valorise byproduct HCl streams in the chemical industry. Bulk alpha -U sub(3)O sub(8) showed an outstanding stability against chlorination, which is crucial for its durability in catalytic tests. UO sub(2) and gamma -UO sub(3) transformed into alpha -U sub(3)O sub(8) under reaction conditions. Uranium deposition on different carriers by dry impregnation concluded the superiority of zirconia as support. HAADF-STEM investigations revealed that the uranium oxide on the surface of this carrier is present in the form of a film-like nanostructure with a thickness ranging from a monolayer to 1 nm as well as atomic dispersion. The effect of variables (temperature, feed O sub(2)/HCl ratio, metal loading, and Cl sub(2) co-feeding) on the performance of U sub(3)O sub(8)/ZrO sub(2) has been studied. The HCl conversion over this catalyst increased with reaction time as a likely consequence of in situ re-dispersion of the original uranium phase into atomically dispersed UO sub(x). As demonstrated by H sub(2)-TPR, the uranium in the generated UO sub(x) phase is more oxidised than in the original U sub(3)O sub(8). Such a highly dispersed active phase is produced faster in the uncalcined sample. The extraordinary stable Cl sub(2) production over U sub(3)O sub(8)/ZrO sub(2) at 773 K for 100 h on stream indicates its potential for application in high-temperature HCl oxidation. Under these conditions, other known catalytic materials suffer from significant deactivation.