Patent ID: 6866748

Claim:
A process for preparing a polysulfide liquor for a pulping process comprising the steps of: i) dividing a clarified white liquor into a polysulfide feed liquor and a cooking liquor; ii) reacting said polysulfide feed liquor with an active oxidant of an insoluble transition metal oxide to form a polysulfide liquor and an insoluble reduced oxidant; iii) separating said insoluble reduced oxidant from said polysulfide liquor to form a recovered liquor and catalyst solution; iv) reactivating said insoluble reduced oxidant by contacting said recovered liquor and catalyst solution with an oxygen-enriched gas to regenerate said insoluble reduced oxidant to form said active oxidant; v) recycling said active oxidant to said reacting step; vi) feeding said polysulfide liquor to said pulping process; and vii) feeding said cooking liquor to said pulping process, wherein said cooking liquor by-passes said reacting step.