Method and apparatus for controlling the catalytic oxidation of cellulose
AssigneeUpm-Kymmene Corporation
InventorsIsko Kajanto, Markus Nuopponen
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Abstract
A method for controlling the catalytic oxidation of cellulose includes using a heterocyclic nitroxyl compound as catalyst oxidizing cellulose in a reaction mixture comprising liquid medium, the catalyst and hypochlorite as main oxidant analyzing one or more oxidative chlorine species dependent on the hypochlorite concentration of the reaction mixture on line in the reaction mixture or in a gas composition which is in contact with the reaction mixture; and controlling supply of hypochlorite to the reaction mixture on the basis of the analysis.
Claims26
A method for controlling the catalytic oxidation of cellulose, comprising:
- using a heterocyclic nitroxyl compound as catalyst, and
- oxidizing cellulose in a reaction mixture comprising liquid medium, the catalyst and hypochlorite as main oxidant,
- analyzing one or more oxidative chlorine species dependent on the hypochlorite concentration of the reaction mixture on line in the reaction mixture or in a gas composition which is in contact with the reaction mixture, and
- controlling supply of hypochlorite to the reaction mixture on the basis of the analysis.
An apparatus for catalytic oxidation of cellulose, comprising
- a reactor, wherein a reaction mixture is placeable in the reactor,
- means for supplying alkaline agent into the reactor,
- means for supplying hypochlorite into the reactor,
- means for measuring pH of the reaction mixture, and
- a gas space in the reactor above the level of the reaction mixture,
- wherein the apparatus further comprises a gas detector for analyzing one or more oxidative chlorine species dependent on the hypochlorite concentration of a gas composition in said gas space, or a redox sensor arranged to be placed in contact with the reaction mixture for analyzing one or more oxidative chlorine species dependent on the hypochlorite concentration of the reaction mixture, said gas detector or redox sensor being in control communication through a control loop with a pump arranged to supply hypochlorite into the reactor so that the level of hypochlorite in the reaction mixture is kept within desired limits on the basis of the analyzed one or more oxidative chlorine species dependent on the hypochlorite concentration.
Dependencies are inferred from the claim text.