(EP722765-A1)      A pressure swing adsorption process for fractionating a multi component mixture comprises: (a) subjecting first (10) (20) (30) and second (10A) (20A) (30A) adsorbent beds in a paired relationship to a continuous cycle having sequential feed, co-current depressurisation, evacuation and countercurrent re-pressurisation stages, the first and second adsorbent beds having opposed entry (12)(22)(32)(12A)(22A)(32A) and discharge (14)(24)(34)(14A)(24A)(34A) sections through which the mixt. passes, the first beds contg. a first adsorbent selected to preferentially adsorb a prim. component of the mixt. and the second beds containing the first adsorbent in the entry section and a second adsorbent selected to preferentially adsorb a secondary component of the mixture located downstream of the entry sections; (b) conducting the feed stage by feeding the first and second beds with mixture so that the primary component is adsorbed within the first adsorbent and the second within the second and to a lesser extent within the first adsorbent to produce a waste stream discharged from the second beds; (c) conducting the co-current depressurisation stages by depressurising the first beds through the second beds to drive the sec. component from the first adsorbent in the first beds to the second beds and also driving part of the primary component adsorbed within the first adsorbent of the first bed into the first adsorbent in the second bed entry section; (d) conducting the evacuation stage by evacuating each of the beds to produce a primary product stream enriched in primary component and a sec product stream enriched in secondary component: and (e) conducting the countercurrent re-pressurisation stages by countercurrently re-pressurising the first and second beds with the waste stream.    USE -   In pressure swing adsorption for fractionating a multicomponent mixture.    ADVANTAGE -   The two groups of adsorbent beds are operated to produce the primary component at high purity and at higher recovery rates than prior art processes utilising groups of adsorbent beds.    (ZA9510568-A)      A pressure swing adsorption process for fractionating a multi component mixture comprises: (a) subjecting first (10) (20) (30) and second (10A) (20A) (30A) adsorbent beds in a paired relationship to a continuous cycle having sequential feed, co-current depressurisation, evacuation and countercurrent re-pressurisation stages, the first and second adsorbent beds having opposed entry (12)(22)(32)(12A)(22A)(32A) and discharge (14)(24)(34)(14A)(24A)(34A) sections through which the mixt. passes, the first beds contg. a first adsorbent selected to preferentially adsorb a prim. component of the mixt. and the second beds containing the first adsorbent in the entry section and a second adsorbent selected to preferentially adsorb a secondary component of the mixture located downstream of the entry sections; (b) conducting the feed stage by feeding the first and second beds with mixture so that the primary component is adsorbed within the first adsorbent and the second within the second and to a lesser extent within the first adsorbent to produce a waste stream discharged from the second beds; (c) conducting the co-current depressurisation stages by depressurising the first beds through the second beds to drive the sec. component from the first adsorbent in the first beds to the second beds and also driving part of the primary component adsorbed within the first adsorbent of the first bed into the first adsorbent in the second bed entry section; (d) conducting the evacuation stage by evacuating each of the beds to produce a primary product stream enriched in primary component and a sec product stream enriched in secondary component: and (e) conducting the countercurrent re-pressurisation stages by countercurrently re-pressurising the first and second beds with the waste stream.    USE -   In pressure swing adsorption for fractionating a multicomponent mixture.    ADVANTAGE -   The two groups of adsorbent beds are operated to produce the primary component at high purity and at higher recovery rates than prior art processes utilising groups of adsorbent beds.    (JP8294612-A)      A pressure swing adsorption process for fractionating a multi component mixture comprises: (a) subjecting first (10) (20) (30) and second (10A) (20A) (30A) adsorbent beds in a paired relationship to a continuous cycle having sequential feed, co-current depressurisation, evacuation and countercurrent re-pressurisation stages, the first and second adsorbent beds having opposed entry (12)(22)(32)(12A)(22A)(32A) and discharge (14)(24)(34)(14A)(24A)(34A) sections through which the mixt. passes, the first beds contg. a first adsorbent selected to preferentially adsorb a prim. component of the mixt. and the second beds containing the first adsorbent in the entry section and a second adsorbent selected to preferentially adsorb a secondary component of the mixture located downstream of the entry sections; (b) conducting the feed stage by feeding the first and second beds with mixture so that the primary component is adsorbed within the first adsorbent and the second within the second and to a lesser extent within the first adsorbent to produce a waste stream discharged from the second beds; (c) conducting the co-current depressurisation stages by depressurising the first beds through the second beds to drive the sec. component from the first adsorbent in the first beds to the second beds and also driving part of the primary component adsorbed within the first adsorbent of the first bed into the first adsorbent in the second bed entry section; (d) conducting the evacuation stage by evacuating each of the beds to produce a primary product stream enriched in primary component and a sec product stream enriched in secondary component: and (e) conducting the countercurrent re-pressurisation stages by countercurrently re-pressurising the first and second beds with the waste stream.    USE -   In pressure swing adsorption for fractionating a multicomponent mixture.    ADVANTAGE -   The two groups of adsorbent beds are operated to produce the primary component at high purity and at higher recovery rates than prior art processes utilising groups of adsorbent beds.