Kemira Oy

Kemira Chemicals Oy

Kemira Agro Oy

Kemira Chemical Oy

Ilkka Turunen

Eva-Liisa Mustonen

Teuvo Maunula

Pekka Oinas

Pirkko J Virta

Process for the preparation of melamine

The invention relates to a process for the preparation of hydrogen peroxide by the anthraquinone process, comprising the oxidation of a hydrogenated organic working solution for the formation of hydrogen peroxide and the extraction of the hydrogen peroxide into an aqueous phase, the oxidation and the extraction being carried out in the same space by directing into one and the same reactor (1) a hydrogenated organic working solution, an oxygen-containing gas and an aqueous extraction solvent in order to form a mixture of three phases, i.e., an organic phase, a gas phase and an aqueous phase, whereby the dissolving of the oxygen in the working solution and the oxidation reaction in the working solution, as well as the transfer of the hydrogen peroxide to the aqueous phase are achieved, whereafter the product leaving the reactor is subjected to phase separation (2) for the recovery of an aqueous solution of hydrogen peroxide. The invention also relates to the use of this process in parallel with a conventional process for the preparation of hydrogen peroxide.

Process for the preparation of hydrogen peroxide

The invention relates to a method for producing hydrogen peroxide by the anthraquinone process, by feeding into the top part of a fixed bed reactor (4) hydrogen (3) and a working solution (1), i.e. an anthraquinone derivative in an organic solvent, and by making these infed substances flow downwardly in the reactor, in order to catalytically hydrogenate the anthraquinone derivative owing to the influence of the catalyst bed (6) and by removing the hydrogenated working solution (9) from the reactor. According to the invention, there is used a fixed bed reactor provided with a stationary catalyst bed that has an open structure. The said working solution is fed into the top part of the reactor at a velocity so high that a separate gas space is not created at the top of the reactor, and that in the top part there is created a dense dispersion of the working solution and gas, and that in the reactor itself there is maintained a relatively high flow velocity, in order to make the said dense dispersion proceed deep down into the catalyst bed. The invention also relates to a fixed bed reactor used for realizing the process.

Process for producing hydrogen peroxide

The invention relates to a method for purification hydrogen peroxide by extraction, wherein

Method for purifying hydrogen peroxide

The invention relates to a process for converting anthrahydroquinone dissolved in an organic solvent to hydrogen peroxide and anthraquinone by causing a mixture of oxygen and anthrahydroquinone to flow concurrently through a reaction zone. According to the invention, the mixture of oxygen and anthrahydroquinone is caused, as an almost continuous mixed dispersion, to flow through the tubular reaction zone at such a velocity that the vacuum-pipe velocity of the liquid therein is higher than 0.05 m/s. The ratio of the length of the tube used as the reactor to its diameter is at minimum approx 10, and it may contain a static mixer made up of one or several parts.

Process for the production of hydrogen peroxide

The invention relates to a process for the production of hydrogen peroxide by the anthraquinone process. A reaction mixture into which there are fed hydrogen or a hydrogen-containing gas and a working solution, i.e. an anthraquinone derivative in an organic solvent, is circulated via a tubular static mixing zone (9) which is continuous or comprises several parts, in order to hydrogenate the anthraquinone derivative in the presence of a solid catalyst, and by removing hydrogenated working solution (13) and gas (11) from the circulating reaction mixture (8). According to the invention, the reaction mixture (14) is circulated (8) via a catalyst-coated static mixing zone (9), where it is simultaneously both mixed and catalyzed.

Growing community of inventors

Oulu, Finland

Ilkka Turunen