The present invention relates in a first aspect to a process for regeneration of an epoxidation reactor that has been used in a process for the preparation of oxidized olefins, the process comprising: (i) providing an
organic solvent, an olefin, an epoxidation agent and water to the reactor comprising a heterogeneous epoxidation catalyst in an epoxidation zone, to form a reaction mixture comprising an olefin,
hydrogen peroxide, water, and an
organic solvent; (ii) subjecting the mixture of (i) in the epoxidation zone of the reactor to epoxidation conditions in the presence of the catalyst, thereby obtaining a mixture comprising water, the
organic solvent and an olefin
oxide; (iii) removing the mixture comprising water, the organic
solvent and the olefin
oxide as obtained in (ii) from the reactor; whereby the precipitate is deposited in the reactor; the regeneration method comprises the following steps: (a) stopping supplying the organic
solvent, the olefin, the epoxidation agent and the water to the reactor; (b) introducing a liquid aqueous
system into the reactor wherein the liquid aqueous
system comprises a chelating agent comprising a bisphosphonic acid of formula (I): (OH) 2 (O =) P-CR1R2-P (= O) (OH) 2 (I) wherein R1 and R2 are independently selected from the group consisting of a
hydrogen atom, a hydroxyl group and a C1 to C5
alkyl group wherein R1 is preferably a hydroxyl group and R2 is preferably a
methyl group (1-hydroxyethylidene-1, 3, 4-
triazole-1-yl), 1, 1-diphosphonic acid, HEDP). A second aspect of the invention relates to a combined preparation process of an olefin
oxide comprising a
preparation stage and a regeneration stage of an epoxidation reactor, the
preparation stage comprising steps (i), (ii) and (iii), whereby precipitates are deposited in the reactor; the regeneration stage comprises steps (a) and (b).