Method for regenerating catalysts used for production of polysulphide cooking liquors

A method of regenerating an activated carbon catalyst, the method comprising:

• producing polysulphide liquor by oxidation of white liquor that contains amounts of iron in the presence of said catalyst, and
• regenerating the activated carbon catalyst by subjecting it to a multi-stage washing to remove a precipitate accumulated in the catalyst which comprises at least one sodium sulphide washing step and which step is carried out at a first point in time and at least one washing step carried out with an acidic washing liquid which is carried out at a second point in time, either before the first point in time or after the first point in time;
• wherein several sodium sulphide washing steps are carried out in sequence, after which at least one washing step is carried out using an acidic washing liquid;
• and
• wherein several washing steps are carried out in sequence using an acidic washing liquid, after which at least one sodium sulphide washing step is carried out;
• in a washing sequence, at least one sodium sulphide washing step and at least one washing step which is carried out using an acidic washing liquid are carried out alternatingly, after which the washing sequence is repeated 0 to 5 times.