Process for operating a plant for preparing an alkanesulfonic acid

A process for operating a plant for preparing an alkanesulfonic acid, wherein said alkanesulfonic acid is prepared by oxidizing an alkylmercaptan, dialkydisulfide and/or dialkylpolysulfide, such that the oxidizing occurs in the presence of an at least stoichiometric amount of an oxoacid of nitrogen relative to an amount of said alkylmercaptan, dialkyldisulfide and/or dialkylpolysulfide during a start-up phase of the plant, the process comprising:

• i) providing an oxoacid of nitrogen in a reactor,
• ii) feeding at least one of an alkylmercaptan containing stream, a dialkydisulfide containing stream, and a dialkylpolysulfide containing stream into the oxoacid of nitrogen in the reactor to give an alkanesulfonic acid containing product mixture, and
• iii) repeating step ii) until an available inner volume of the reactor is filled completely with the alkanesulfonic acid containing product mixture obtained in step ii),
• iv) feeding additional oxoacid of nitrogen into the reactor, when an amount of the oxoacid of nitrogen provided in step i) is not enough to fill the available inner volume of the reactor with the product mixture obtained in step ii),
• v) feeding an oxygen containing fluid stream into the reactor, when the available inner volume of the reactor is completely filled with the product mixture obtained in the step ii) and/or in the step iii),
• vi) removing at least part of the alkanesulfonic acid containing product mixture from the reactor, and
• vii) feeding at least one of the alkylmercaptan containing stream, the dialkydisulfide containing stream, and the dialkylpolysufide containing stream into the reactor to yield a reaction mixture,
• wherein:
• said alkylmercaptan, dialkyldisulfide and/or dialkylpolysulfide is identical with the alkylmercaptan, dialkyldisulfide and/or dialkylpolysulfide of any of the preceding steps;
• and
• a volume of the the alkylmercaptan containing stream, the dialkyldisulfide containing stream and the dialkylpolysulfide containing stream, fed into the reactor in step vii), equals a volume of the product mixture removed from the reactor in step vi).