# US 5,705,040 A · Process for preparing a substantially pure aqueous solution of hydrogen peroxide > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,705,040 A - Document ID: US5705040A - Status: Granted - Kind: A - Application number: 08/602,089 - Filed: 1996-02-15 - Granted: 1998-01-06 - Earliest claimed: 1995-02-15 - Inventors: Pekka Johnsson; Tapio Mattila; Kari Saari - Web page: https://patentgrep.com/patent/US5705040A ## CPC - C01B 15/013: Separation; Purification; Concentration - Y10S 159/15: Special material - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A process for preparing a substantially pure aqueous solution of hydrogen peroxide is described. An impure hydrogen peroxide solution is vaporized in a vaporizer to form a vapor containing hydrogen peroxide and a concentrated hydrogen peroxide solution in equilibrium therewith. The solution also contains impurities. A substantially pure hydrogen peroxide solution is obtained by a partially condensing the vapor containing hydrogen peroxide. In addition to the solution, a residual vapor, in equilibrium with the solution and having a lower hydrogen peroxide concentration, can be condensed in a separate condenser. The concentration of the hydrogen peroxide solution obtained by the process can be regulated, for example, by regulating the condensation efficiency of the partial condensation. ## Claims ### Claim 1 A process for preparing a substantially pure aqueous solution of hydrogen peroxide, comprising: vaporizing an aqueous solution containing hydrogen peroxide to form a vapor containing hydrogen peroxide and a liquid phase containing hydrogen peroxide and impurities; separating the vapor from the liquid phase and leaving nonvolatile impurities in the liquid phase; and partially condensing the vapor to divide it into a condensate and a residual vapor in equilibrium with the condensate, thereby obtaining the condensate as the product of the process, the condensate being substantially pure and having a higher hydrogen peroxide concentration than the residual vapor. ### Claim 2 (depends on 1) The method according to claim 1 wherein the step of partially condensing the vapor takes place at a pressure of from about 30 mbar to about 100 mbar. ### Claim 3 (depends on 2) The method according to claim 2 wherein the step of partially condensing the vapor comprises condensing by external heat transfer using a vapor-cooling heat-transfer medium. ### Claim 4 (depends on 3) The method according to claim 3 wherein the vapor-cooling heat-transfer medium is water. ### Claim 5 (depends on 2) The method according to claim 2, and further comprising: forming the vapor containing hydrogen peroxide in a vaporizer, the vapor being in equilibrium with a liquid phase which contains hydrogen peroxide and impurities; separating water from the vapor in a drop separator; and partially condensing the vapor in a condenser. ### Claim 6 (depends on 1) The method according to claim 1 wherein the step of partially condensing the vapor takes place at a pressure of from about 50 mbar to about 80 mbar. ### Claim 7 (depends on 1) The method according to claim 1 wherein the step of partially condensing the vapor comprises condensing by external heat transfer using a vapor-cooling heat-transfer medium. ### Claim 8 (depends on 7) The method according to claim 7 wherein the vapor-cooling heat-transfer medium is water. ### Claim 9 (depends on 1) The method according to claim 1, and further comprising: forming the vapor containing hydrogen peroxide in a vaporizer, the vapor being in equilibrium with a liquid phase which contains hydrogen peroxide and impurities; separating water from the vapor in a drop separator; and partially condensing the vapor in a condenser. ### Claim 10 (depends on 8) The method according to claim 8 wherein the vapor is formed from an impure hydrogen peroxide fed to the vaporizer from a process for the preparation of hydrogen peroxide. ### Claim 11 (depends on 10) The method according to claim 10 wherein the process for the preparation of hydrogen peroxide is an anthraquinone process. ### Claim 12 (depends on 1) The method according to claim 1, and further comprising: condensing the residual vapor produced by the step of partially condensing in a second condenser to form a dilute hydrogen peroxide solution; and returning the dilute hydrogen peroxide solution to the vaporizer. ### Claim 13 (depends on 1) The method according to claim 1 wherein the concentration of the hydrogen peroxide solution in the condensate is from about 15 weight % to about 75 weight %. ### Claim 14 (depends on 13) The method according to claim 13 wherein a desired concentration of the hydrogen peroxide solution within a range of from about 15%-75% by weight is prepared by regulating the hydrogen peroxide concentration in the vapor to be condensed. ### Claim 15 (depends on 13) The method according to claim 13 wherein a desired concentration of the hydrogen peroxide solution within a range of from about 15%-75% is prepared by regulating the efficiency of the partially condensing step. ### Claim 16 (depends on 13) The method according to claim 13 wherein the condensate comprises about 35% by weight hydrogen peroxide. ### Claim 17 A method for preparing a substantially pure aqueous solution of hydrogen peroxide, comprising: vaporizing an aqueous solution containing hydrogen peroxide to form a vapor containing hydrogen peroxide and a liquid phase containing hydrogen peroxide and impurities; separating the vapor from the liquid phase and leaving nonvolatile impurities in the liquid phase; partially condensing the vapor by external heat transfer using a vapor-cooling heat-transfer medium at a pressure of from about 30 mbar to about 100 mbar to form a condensate and a residual vapor in equilibrium with the condensate, the condensate being substantially pure and having a higher hydrogen peroxide concentration than the residual vapor; condensing the residual vapor in a second condenser to form a dilute hydrogen peroxide solution; and returning the dilute hydrogen peroxide solution to the vaporizer. ### Claim 18 (depends on 17) The method according to claim 17 wherein the step of partially condensing the vapor takes place at a pressure of from about 50 mbar to about 80 mbar. ### Claim 19 (depends on 17) The method according to claim 17 wherein the vapor-cooling heat-transfer medium is water. ### Claim 20 (depends on 17) The method according to claim 17 wherein the vapor is formed from an impure hydrogen peroxide fed to the vaporizer from a process for the preparation of hydrogen peroxide.