Process for regeneration of an epoxidation reactor

A process for the regeneration of an epoxidation reactor, the epoxidation reactor having been used in a method for the preparation of an olefin oxide comprising:

• (i) providing an organic solvent, an olefin, an epoxidation agent and water to the reactor, which comprises an heterogeneous epoxidation catalyst in an epoxidation zone, so that a reaction mixture comprising olefin, hydrogen peroxide, water and organic solvent is formed;
• (ii) subjecting the mixture of (i) in the reactor's epoxidation zone to epoxidation conditions in the presence of the catalyst, thereby obtaining a mixture comprising water, the organic solvent and olefin oxide;
• and
• (iii) removing the mixture comprising water, the organic solvent and olefin oxide obtained in (ii) from the reactor;
• whereby a precipitate is deposited in the reactor;
• the process for the regeneration comprising:
• (a) stopping providing organic solvent, olefin, epoxidation agent and water to the reactor;
• and
• (b) introducing a liquid aqueous system into the reactor, wherein the liquid aqueous system comprises a chelating agent, which comprises a diphosphonic acid of formula (I)
• wherein R1 and R2 are independently selected from the group consisting of hydrogen atom, hydroxyl group and C1 to C5 alkyl group.

A combined process for preparation of an olefin oxide comprising a preparation stage and a stage of regeneration of the epoxidation reactor,

• the preparation stage comprising:
• (i) providing an organic solvent, an olefin, an epoxidation agent and water to the reactor comprising an heterogeneous epoxidation catalyst in an epoxidation zone, so that a reaction mixture comprising olefin, hydrogen peroxide, water and organic solvent is formed;
• (ii) subjecting the mixture formed in (i) in the epoxidation reactor to epoxidation conditions in the presence of the catalyst, thereby obtaining a mixture comprising water, the organic solvent and olefin oxide;
• (iii) removing the mixture comprising water, the organic solvent and olefin oxide obtained in (ii) from the reactor;
• whereby a precipitate is deposited in the reactor;
• the regeneration stage comprising:
• (a) stopping introducing the mixture of (i) into the reactor;
• (b) introducing a liquid aqueous system into the reactor, wherein the liquid aqueous system comprises a chelating agent, which comprises a diphosphonic acid of formula (I)
• wherein R1 and R2 are independently selected from the group consisting of hydrogen atom, hydroxyl group and C1 to C5 alkyl group, wherein R1 is a hydroxyl group and R2 is a methyl group (1-hydroxy ethylidene-1,1-diphosphonic acid, HEDP).