United States Patent (19) 1 3,714,342 Kabisch (45) Jan. 30, 1973 54 PROCESS FOR THE PRODUCTION OF 56) References Cited HYDROGEN PEROXDE UNITED STATES PATENTS (75) Inventor: Gerhard Kabisch, Rheinfelden, Ger 2,804,376 8/1957 Haller et al............................. 23/207 many 2,966,398 12/1960 Jenney................................. 260/369 73 Assignee: Deutsche Gold-und Silber-Scheide 2,537,655 1/1951 Daursey et al.......................... 23.1207 anstalt vormals Roessier, Frankfurt 2,537,516 17951 Daursey et al.......................... 23.1207 (Main), Germany 22) Filed: Sept. 2, 1970 Primary Examiner-Oscar R. Vertiz Assistant Examiner-Hoke S. Miller 21 ) Appl. No.: 68,977 Attorney-Cushman, Darby & Cushman 30 Foreign Application Priority Data 57 ABSTRACT Sept. 10, 1969 Germany - - - - - - - - - - - P 1945 75.46 Hydrogen peroxide low in carbon containing impuri ties is produced by the anthraquinone process first by 52 U.S. Cl.................... 4231588, 260/369, 4231589 water topping off (stripping) the crude H.O, product 51 Int. Cl.............................................. C01b 15/02 accumulating in the extraction step of the cyclic 58 Field of Search ......................... 23/207; 260/369 process and then distilling the water stripped HO - product. 8 Claims, 2 Drawing Figures PATENTEDJAN3O 1973 3,714,342 INVENTOR 2e2%z7 é25%sca/ BY, (1/11---, 6-4 16/6%ATTORNEYs 3,714,342 2 PROCESS FOR THE PRODUCTION OF leaving via conduit 45 while from the column bottom HYDROGEN PEROXDE 18 an about 60-70 percent H2O, (usual commercial The present invention is concerned with a process quality with a carbon content of 80-500 mg. C/1) is for the production of a highly concentrated, low carbon drawn off. A portion of the H2O, is drawn off via con hydrogen peroxide by the so-called anthraquinone duit 46 and the rest recycled via conduit 47, reboiler 16 process (AO-process). and conduit 48. In the depicted type of the customary It is known according to the AO-process to dissolve an anthraquinone derivative, e.g., are alkyl anthraquin industrial H2O2 working up by distillation it is generally one or alkyl tetrahydroanthraquinone, as the reaction valid that carbon rich H2O, crude products yields car carrier in a solvent and then to hydrogenate the thus O bon rich H2O, distillates. Low carbon, quality HO, up obtained working solution to such an extent in the to now could only be recovered by industrially expen presence of a catalyst, e.g., palladium, that about 50 sive measures, as for example, a double distillation. percent of the quinones are converted into the cor As low carbon products, there should be understood responding hydroquinones. In the next process step such qualities whose C-content in the highly concen (oxidation step), the hydroquinone solution is treated S trated distillates lies below 80 mg. C/1 and especially with an oxygen containing gas, e.g., air, as a result of below 50 mg. C/l. This type of low carbon quality HO, which the quinone is reformed while simultaneously is often designed as "practically free of carbon', since hydrogen peroxide is formed. The hydrogen peroxide is one is in a C range in which there can no longer be washed out of the organic phase with water in the next determined with the usual quick methods of determina process step (extraction step) and then is present as the tion, for example coulombmetric automatic titration, so-called crude H2O, in a concentration of, for the most whether the C content is due to organic impurities or is part, about 15-30 weight percent. While the working due to dissolved CO2 (from the air). In the United solution is returned to the hydrogenation step whereby States low carbon H.O. products are designated “Food the cycle is closed and can be started anew the crude grade Quality' if the carbon content in 30 percent H2O, in most cases is subjected to a purification and, in 25 materials lies below 20 mg. C/l. a given case, more highly concentrated before it is Surprisingly, it has now been found that there can be further processed or enters commerce. obtained a highly concentrated, low carbon H.O. Most of the usual commercial hydrogen peroxide product that can be diluted to a "Food grade Quality” products today have a concentration of 50-70 weight 30 by a single distillation if there is employed as the start percent. In these commercial products, it is exclusively ing product for the distillation a product first concen a matter of hydrogen peroxide distillates which are trated by water topping off (stripping). In comparison more or less strongly contaminated with organic to a total distillation, the energy saving process of water materials from the AO cyclic process. The content of stripping simultaneously removes with the stripped off organic impurities in the distilled product corresponds 35 water the main amount of the volatile organic impuri to the analytically determined carbon value which in ties from the starting product for the distillation. The the 50-70 percent commercial product ranges within previously removed volatile organic impurities no the boundaries of about 80-500 mg. C/l H.O. longer contaminate the H2O2 distillate in the sub The production of the described commercial quality. sequent distillation while the nonvolatile organic impu takes place in all present industrially operating 40 processes basically similar to the process principle rities are removed by the distillation from the circula shown schematically in FIG. 1 of the drawings. tion evaporator 13, 14 by way of conduit 17 (FIG. 1). FIG. 2 shows the process according to the present in The described process step of the invention then is of vention. especial significance if the crude extraction product Referring more specifically to FIG. 1 of the drawings, 45 has a lower H2O, concentration (for example, 15-20 the crude H2O (about 15-30 percent H.O.) discharg weight percent), then the generally customary H, O, ing from the bottom of the extraction column 11 goes concentration in the product injected into the distilla via conduit 40 to a subsequent apparatus 12 where it is tion (20-30 weight percent). subsequently treated, for example by washing with or Of especial importance, however, is the present in ganic solvents or by purification with adsorption agents SO vention, however, as a means of obtaining the objects and then flows via conduits 41 and 42 to a circulation of Kabisch and Wittmann application Ser. No. 69,152 evaporator 13 and 14 (also including conduits 43, 44 filed 69,152 even date, and now abandoned, and based and 45) in which there is maintained a HO concentra on German priority application 1945753.5. The entire tion of 60-70 percent and is evaporated there. In this disclosure of said Kabisch and Wittmann application is regard see the equilibrium curve HO concentration in 55 hereby incorporated by reference. the liquid and H2O, concentration in the vapor of G. In the process there is produced first in the extrac Scotchard et al., J. Amer. Chem. Soc., Vol. 74, 3715 tion step as highly as possible concentrated HO crude (1952). To prevent enrichment of the none volatile product whereby concentrations preferably are ob organic impurities as a safety measure there is continu tained which are over 40 weight% HO. However, the ously drawn off a small amount of liquid (about 3-10 60 concentration of the crude H2O, product employed can percent based on the total amount of H. O.) from the be between 25 and 55 weight %. The thus obtained circulation evaporator by way of valve 43 and conduit crude extraction product is then by further water 17. stripping strengthened to concentration of over 45 per The HO/HO, mixture evaporated in evaporator 13, cent and up to 85%, preferably 55-75% H.O.. At the 14 goes via conduit 44 to column 15 provided with a 65 same time by the water stripping the main amount of further reboiler 16. The mixture is fractionated in the the volatile organic compounds are removed from the column with water taken off at the column head 19 and H2O, concentrate. 3,714,342 3 4 This HO, concentrate can now either be applied portion is recycled via conduit 61 to the circulation directly to the H.O, distillation or it can first be diluted evaporator. The product leaving the top of evaporator with water and then distilled. A direct distillation of 29 goes via conduit 62 to the middle of fractionating highly concentrated H.O, product is only possible on a column 32 provided with a further reboiler 31. The basis of safety if special apparatus conditions are full 5 vaporized HO/HO, mixture is separated in column filled (for example, carrying out the distillation in verti 32. Both the head product removed through conduit 33 cal film evaporators). The production of low carbon, and the sump product removed through conduit 34 ac quality HO, is produced in an industrially simple and cumulate as low carbon condensates. While the head safe manner if the H.O., concentration obtained by product, water, in a given case, can be used either en water stripping first is diluted with water to a HO con O tirely or partially for HO, dilution in reservoir 26 by s tent of 20-30 percent and the diluted H2O, distilled. In passing it via conduit 63 (or can be removed via con contrast to the known methods of working two substan duit 64), the HO condensate drawn off via conduit 34 tial advantages then result: is a highly valuable product which qualitatively cor 1. The amount of the carbon rich portion drawn off 5 responds to a material which, until now, could only be from the circulation evaporator can be held lower, obtained by a double distillation.