Application of Pt/Al2O3 catalysts produced by sol-gel process to uranyl ion reduction

Various kinds of active alumina supports were obtained by the Institute of Nuclear Chemistry and Technology (INCT) sol-gel process in the following steps: (1) preparation of alumina sols by extraction of nitrates with Primene JMT from aluminium nitrate solution; (2) gelation to spherical particles (with diameter < 100 m) by extraction of water from sol emulsion in 2-ethyl-1-hexanol; (3) sometimes conversion of NO3- stabilized gel to OH- form by reaction with ammonia; (4) calcination of gels to gamma-Al2O3 with specific surface area > 100 m(2)/g at 500 degrees C. The powders were then impregnated with chloroplatinic acid and recalcined at 500 degrees C. Catalysts were also prepared by direct gelation of alumina sol containing hydroplatinic acid followed by steps (3) and (4), Pt/Al2O3 catalysts were used for the reduction of 1 M UO2(NO3)(2)(-) 0.5 M HCOOH solution with hydrogen at atmospheric pressure. The course of the reduction was controlled analytically and by measuring the U(VI)/U(IV) redox potetitial. It was concluded that the catalysts obtained by impregnation of the supports prepared from nitrate stabilized eels exhibit the best activity and stability.