Patent ID: 11912571
Assignee: EVONIK OPERATIONS GMBH
Field: Chemical engineering (Chemistry)
Classification: CPC C  B | IPC B  C

Claim 7:
8. A process for producing hydrogen peroxide by an anthraquinone process, comprising the steps of:
a) hydrogenating a working solution comprising an alkylanthraquinone and/or an alkyltetrahydroanthraquinone and at least one solvent for said alkylanthraquinone and/or alkyltetrahydroanthraquinone with a gas comprising molecular hydrogen in the presence of a hydrogenation catalyst to provide a hydrogenated working solution;
b) oxidizing hydrogenated working solution of step a) with a gas comprising molecular oxygen to provide an oxidized working solution containing dissolved hydrogen peroxide;
c) extracting hydrogen peroxide from oxidized working solution of step b) with an aqueous extractant to provide a dilute aqueous hydrogen peroxide solution containing from 25 to 50% by weight hydrogen peroxide;
d) concentrating dilute aqueous hydrogen peroxide solution of step c) in a distillation unit comprising a hydrogen peroxide evaporator, a distillation column receiving vapor from the hydrogen peroxide evaporator and a vapor compressor receiving overhead vapor from the distillation column and passing compressed vapor as heating medium to the hydrogen peroxide evaporator to provide a concentrated aqueous hydrogen peroxide solution, containing from 45 to 90% by weight hydrogen peroxide, and an aqueous condensate;
e) purifying aqueous condensate of step d) in a purification unit by passing it through a bed of a cation exchange resin in its protonated form to provide a purified condensate wherein the bed of cation exchange resin is replaced by fresh resin when the concentration of iron, nickel or chromium in said purified condensate increases to a value of more than 0.02 mg/l; and
f) reusing purified condensate of step e) as (i) an aqueous extractant in extracting step c), (ii) a column reflux for the distillation column in concentrating step d), (iii) a diluent in a step of diluting an aqueous hydrogen peroxide solution, or (iv) in any combination of (i) to (iii).